Application of saphenous nerve infrapatellar branch protection technique in total knee arthroplasty

Application of saphenous nerve infrapatellar branch protection technique in total knee arthroplasty | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Application of saphenous nerve infrapatellar branch protection technique in total knee arthroplasty zhi qiang mao, Kai Li, Zhou Zhang, Ting Li, Jian-hua Lu, Meng-Qiang Fan, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6057173/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 14 Oct, 2025 Read the published version in BMC Musculoskeletal Disorders → Version 1 posted 12 You are reading this latest preprint version Abstract Objective Compared with the traditional surgical method, this study aims to explore a saphenous nerve infrapatellar branch protection technique to address the issue of numbness and pain in the anterolateral skin of the knee joint after total knee arthroplasty, thereby improving patient satisfaction. In this study, we compared the effects of the modified TKA surgical incision and the traditional median surgical incision on anterolateral skin numbness and pain, as well as the protective techniques targeting the infrapatellar branch of the saphenous nerve. The goal was to reduce sensory disorders in the anterolateral skin of the knee, alleviate pain in the operative area, and ultimately improve patient satisfaction after surgery. Methods In this study, 60 patients who underwent TKA for the first time at Zhejiang Provincial Hospital of Traditional Chinese Medicine between January 2022 and June 2023 were selected and randomly divided into two groups: Modified group (M group n = 31) and Traditional group (T group n = 29). In M group, a modified approach was used to incise and visualize the articular cavity. The skin incision was the same length as that in the classic median knee surgery, and the visualization of the articular cavity was performed in two steps. First, an incision was made above the knee joint line, similar to the classic medial parapatellar approach, but the proximal end was extended proximally along the medial femoral tendon to relax the knee-extension device. In the second step, the proximal incision was retracted to both sides, and the skin below the joint line was incised longitudinally to protect all subcutaneous soft tissues in the superficial layer of the patellar tendon, which contained branches of the infrapatellar branch of the saphenous nerve, while maintaining skin tension. In T group, the articular cavity was exposed through the traditional medial parapatellar approach. All 60 patients underwent TKA performed by the same attending surgeon, and the same brand of knee prosthesis was uesd for all patients (no patellar surface replacement, only patellofemoral plasty). The skin sensation around the incision was statistically observed preoperatively, and at 2 weeks, 1 month, 3 months, 6 months, and 1 year postoperatively. This included the size of the distribution area of skin numbness and changes in numbness. The two groups were compared and analyzed to determine differences in anterior-lateral knee skin numbness and pain between the two surgical techniques. Data were collated through statistical analysis to compare the differences in numbness and pain between the two groups. This study aimed to explore whether the improved surgical technique was more effective in reducing the occurrence of numbness and pain in the postoperative period and to draw a conclusion. Results There was no statistically significant difference in the baseline characteristics between the two groups (P > 0.05). The P-value of the HSS scores of the two groups was greater than 0.05 in the preoperative, at 7 days postoperatively, at 2 weeks postoperatively, and at 1 month postoperatively, indicating no statistically significant difference. The P-value of the VAS scores of the two groups were greater than 0.05 preoperatively and at 1 day postoperatively, indicating no statistically significant difference. However, the P-value of the VAS scores were less than 0.001 at 3 days postoperatively, 7 days postoperatively, and 2 weeks postoperatively, indicating a statistically significant difference. The P-values for the numbness area of the two groups were less than 0.001 at 2 weeks postoperatively, 1 month postoperatively, 3 months postoperatively, 6 months postoperatively, and 1 year postoperatively, indicating a statistically significant difference. The area of numbness was smaller in the group with the modified surgical technique compared to the traditional surgery at the same time points. Additionally, numbness on the outer side of the incision in some of the patients treated with the modified technique was completely recovered. Conclusion The modified incision-exposure technique used in this study effectively protects the infrapatellar branch of the saphenous nerve without causing operational difficulties in osteotomy, ligament balancing, gap balancing, or prosthesis implantation during total knee replacements. This technique results in a smaller area of postoperative skin numbness compared to the traditional surgical method, with less postoperative pain and faster recovery. Knee joint Saphenous nerve Protection Technology Total Knee Arthroplasty Modified surgery Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Introduction Knee Osteoarthritis (KOA) is a common degenerative joint disease whose incidence significantly increases with age. Typical symptoms include joint pain, limited mobility, and in severe cases, joint deformity or even disability. These symptoms not only causes pain, but also jeopardize health and affects the quality of life [ 1 – 2 ] . Total Knee Arthroplasty (TKA) is currently the treatment of choice for end-stage knee osteoarthritis. Studies have found that the 10-year survival rate of patients after TKA has exceeded 90% [ 3 ] . With the increasing elderly population in China, the number of KOA patients with receiving TKA is also rising. As people's cognitive concepts and living standards improve, patients' expectations for postoperative outcomes are also increasing. Despite recent advancements in TKA surgery, studies have shown that while over 80% of patients are satisfied with their new joints, approximately 20% remain dissatisfied [ 4 ] . Postoperative pain is a potential contributing factor to this dissatisfaction. Beswick et al [ 5 ] reported that 10–34% of post-TKA patients experience moderate to severe pain, leading to dissatisfaction. Postoperative lateral knee cutaneous dysesthesia may also be a contributing factor, with Macdonald [ 6 ] et al reporting an incidence of lateral knee numbness ranging from 37–100% after TKA. Tanavalee et al [ 7 ] reported an area of skin numbness (AON) of up to 51.7cm 2 two weeks after TKA, which gradually reduced to 2.1 cm² after one year. The traditional TKA procedure, which involves a medial knee incision and a medial parapatellar approach, often damages the infrapatellar branch of the saphenous nerve distal to the incision. As a result, up to 100% of patients experience lateral knee skin numbness after knee arthroplasty as an unavoidable complication [ 8 ] . This numbness lasts longer and is more painful in patients after TKA, and some patients do not achieve the expected therapeutic effect. Addressing these refractory numbness and pain symptoms is essential to improve patient satisfaction. There are no established techniques for protecting the saphenous nerve branches, either because surgeons have not paid enough attention to the adverse outcomes caused by nerve injury or because dissection and isolation of the nerve during surgery are time-consuming and laborious. However, our team has developed a technique that is both fast and effective in protecting the infrapatellar branch of the saphenous nerve. A study of patients who underwent a modified TKA procedure found less subjective numbness and pain in the operative area, with good efficacy. Therefore, this study aims to compare and analyze the postoperative numbness and pain between patients who underwent modified and traditional surgical techniques, to evaluate the effect of modified surgery on postoperative numbness and pain, and to provide new insights for clinical practice. 2. Materials and methods 2.1 Study design The study protocol was reviewed and approved by the Ethics Committee of the First Affiliated Hospital of Zhejiang University of Traditional Chinese Medicine, and obtained the unique identification number of research registration (2025-KS-228-01). Written informed consent for participation was obtained from all participants. All procedures were performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. 2.2 Study population In this study, 68 patients who underwent TKA for the first time at Zhejiang Provincial Hospital of Traditional Chinese Medicine between January 2022 and June 2023 were selected and randomly divided into Modified group (M group) and Traditional group (T group), with 34 patients in each group. Inclusion criteria and exclusion criteria are as follows: Inclusion criteria: a. The patient had her first unilateral total knee replacement. b. There was no previous history of periprosthetic knee surgery. c. Preoperative skin sensation was normal in both knees. d. No peripheral or central nervous system disease. e. Ability to cooperate with the physician's physical examination and complete questions and answers. f. Informed consent for treatment and trial protocol. Exclusion criteria: a. Postoperative infections and revision. b Preoperative skin sensory deficits in the affected knee. c. The patient has peripheral neuropathy and central nervous system abnormalities. d. Unable to determine efficacy, lost to follow-up and incomplete information. 2.3 Randomization The participants were randomly assigned to either the experimental group or the control group using a computer-generated randomization sequence. To ensure allocation concealment, the randomization list was prepared by an independent statistician who was not involved in the recruitment or treatment processes. The allocation sequence was stored in sealed, opaque envelopes, which were opened only after the participants had completed the baseline assessments and provided informed consent. This method ensured that both the researchers and participants were blinded to group assignment until the intervention began. The randomization ratio was 1:1, with an equal number of participants allocated to each group. This approach minimized selection bias and ensured the comparability of the two groups at baseline. 2.4 Methods In M group, the articular cavity was opened and exposed using a modified method. The skin incision was the same length as that in the classical median knee surgery, and the exposure of the articular cavity was performed in two steps. The first step was similar to the classical medial parapatellar approach above the knee joint line, but the proximal end was extended proximally along the medial femoral tendon to relax the knee-extension device, In the second step, the proximal incision was retracted laterally, and the skin below the joint line was cut longitudinally while maintaining skin tension to protect all subcutaneous soft tissue in the superficial layer of the patellar tendon, which contains the infrapatellar branch of the saphenous nerve ( Fig 1 ). In T group, the joint cavity was exposed using the traditonal medial parapatellar approach. All 68 TKA surgeries were performed by the same attending surgeon, and the same brand of knee prosthesis was used (no patellar surface replacement, only patellofemoral plasty). The preoperative and postoperative skin sensation around the incision was statistically observed in both groups, including the size and changes in the distribution area of skin numbness. A comparative analysis was conducted to determine the differences in anterolateral knee joint numbness and pain between the two surgical techniques. The gender, age, height, weight, affected side, operative time, surgical bleeding, length of surgical incision, VAS(visual analog scale) score, and HSS(Hospital for Special Surgery) knee score of patients in both groups were recorded separately. 2.5 Surgical Procedures preoperative preparation The patients were assessed for the degree of internal and external knee deformity, knee mobility, pain VAS score [21] , HSS score [22] , and underwent improved preoperative related examinations, such as full-length standing radiographs of both lower limbs, to assess the risk of surgery. Surgical steps After successful general anesthesia, the patient was placed in the supine position. The level of the knee joint line was determined using the lower edges of the medial and lateral knee eyes as markers, and this was marked with a marker pen ( Fig 2 ). After driving the blood out with a tourniquet, the affected limb was routinely disinfected and draped. A longitudinal incision was made in the middle of the anterior knee, extending from 3 cm proximal to the upper edge of the patella to the medial end of the tibial tuberosity distally. The incision was revealed in Two steps: First, above the joint line level, a conventional medial parapatellar incision was used to expose the joint cavity. Then, using a retractor, the incision was pulled to both sides to cut the skin below the joint line under tension, while retaining the patellar tendon in the superficial layer of the soft tissues (which contains the infrapatellar branch of the saphenous nerve). To increase the laxity of the knee-extension device, the quadriceps tendon could be incised proximally to the extent necessary to turn the patella. Residual meniscus, and the anterior cruciate ligament were removed. The knee was positioned in flexion, and the medial and lateral collateral ligaments were protected. Distal femoral osteotomy was performed after intramedullary positioning of the femur. The prosthesis was selected with a 5-7 degree valgus alignment. A “four-in-one” osteotomy guide was used for the femoral condyles, and for the PS prosthesis, additional intercondylar osteotomy was performed for the upper and lower beveled cuts. The femoral prosthesis specimen was tested and mounted. The tibial osteotomy mold was tested to determine the size of the tibial prosthesis. Tibial osteotomy was performed, and the rotational alignment of the tibial prosthesis and the appropriate type were determined. The proximal tibial bone bed was prepared, the specimen was removed, and the knee was tested for equal flexion or extension clearance and correct lower extremity alignment. The bone surface was repeatedly rinsed with a high-pressure pulse lavage gun, dried, and bone cement was mixed. All prostheses were installed and fixed in the dough stage. The spacer was measured and installed. The patellar articular surface was trimmed and shaped with bone biting forceps. The patellar tracking was checked to ensure good knee flexion or extension mobility and joint stability. The tourniquet was released to stop bleeding, and bleeding points were treated with electrocautery. The corresponding tissues were sutured layer by layer, and the wound was wrapped with a cotton-padded bandage under pressure. The operation was then completed. Preoperative and intraoperative treatment The physician instructed the patient to use Bactrim ointment and chlorhexidine to disinfect the skin before surgery. Patients in both groups were administered 2 g of cefazolin sodium during preoperative induction of anesthesia, 40 g of bone cement mixed with 1,000 mg of vancomycin intraoperatively to prevent infection, and 1 g of tranexamic acid to reduce bleeding. Post-operative treatment Both groups of patients received postoperative intensive care, including nasal cannula oxygen and continuous monitoring of vital signs. Symptomatic treatments were provided, such as gastric protection, analgesia, antiemetics, neurotrophic support and nutritional support. Additionally, nebulization therapy was administered to improve ventilation and other symptomatic treatments were given as needed. 2.6 Observation indicators Skin sensory conditions The skin sensation around the incision of the affected knee was observed in both groups before surgery, and at 14 days, 1 month, 3 months, 6 months, and 1 year postoperative. This included whether the skin on the lateral side of the surgical incision felt numb after surgery, as well as the size and change of the numbness area (the area of numbness of the skin (AON) was measured in cm 2 ) [7] . Specific measurements were taken as follows: First, a sterile cotton swab was lightly touched on the outer side of the incision to determine if sensation was present and if numbness was felt, thereby identifying the approximate range of sensory abnormality. Then, tests were conducted in an outward-to-inward and top-to-bottom order, with a double-knee comparison to identify specific areas of abnormal sensation. The extent of the numbness was drawn with a marker pen, and the size of the area was measured using a ruler (see Fig 3 and Fig 4 ). Regular postoperative follow-ups were performed to observe whether the numbness improved and whether the area of numbness decreased. 2.7 Clinical efficacy evaluation 1）The pain scores of the patients in both groups were observed and evaluated preoperatively, and on postoperative days 1, 3, 7, and 14 using the Visual Analog Scale (VAS) [21] . The VAS was administered as follows: A horizontal line was drawn on a piece of paper, divided into 11 equal intervals labeled “0” to “10”. “0” indicates no pain, while “10” indicates extremely painful and intolerable pain. Patients were asked to mark their pain level on the line according to their subjective feelings. 2）The HSS scores [22] of patients in both groups were observed preoperatively, and on postoperative day 1, 7, and 14, as well as at month 1 postoperatively. The scores were evaluated according to the Hospital for Special Surgery (HSS) scoring system, which includes seven main aspects: pain, function, range of motion, muscle strength, flexion contracture, extension lag, and stability. Patients were able to assess their affected knee joints based on the criteria for each item. 2.8 Sample size The sample size was calculated using G * Power (http://www.gpower.hhu.de/) power analysis. We used a two-tailed matched-pairs t test with the following settings, and our primary outcome measure had an effect size of 0.74, a significance level (alpha) of 0.05, and a power of 0.80. Based on these criteria, a sample size of 30 patients was required for both groups. Finally, to compensate for the potential loss of follow-up, we enrolled a total of 68 patients. 2.9 Statistical analysis Data analysis was performed using SPSS 26.0 statistical software. Due to the relatively small sample size, the Shapiro–Wilk test was applied to test the normality of data distributions. Normally distributed data were expressed as mean ± SD, and group comparisons were performed using independent samples t-test. Categorical variables were analyzed using Pearson’s chi-square. Based on these test results, we selected appropriate parametric or non-parametric statistical tests. 3. Result In this randomized clinical trial, 68 patients scheduled for total knee arthroplasty were initially enrolled. After applying the exclusion criteria, 8 patients were excluded from the study, including 1 patient who was unable to comply with measurements, 4 patients who withdrew during the study, and 3 patients who were lost to follow-up postoperatively. Ultimately, 60 patients were included in the final analysis, as shown in the Fig. 5 . 3.1 Comparison of general information By statistically analyzing the basic data of the two groups of patients. The p-values for affected side, gender, age, BMI, length of surgical incision, surgical time, and intraoperative hemorrhage were all greater than 0.05, indicating no statistically significant differences. See Table 1 . Table 1 Basic data of the two groups of patients M group(n = 31) T group(n = 29) P-value Age(years)* 67.20 ± 4.28(62–81) 66.90 ± 4.07(61–79) 0.785 BMI(Kg/㎡)* 23.06 ± 1.48(21.5–26.8) 23.17 ± 1.45(21.37–26.41) 0.765 Sex(male / female) 16(53.3%)/15 17(58.6%)/12 0.791 Length of surgical incision(cm)* 15.28 ± 0.93(14–17) 15.17 ± 0.89(14–17) 0.678 Surgical time(min)* 80 ± 15.05(75–104) 83 ± 14.75(71–106) 0.596 Intraoperative bleeding(ml)* 112.17 ± 18.15(80–150) 110.84 ± 19.63(90–150) 0.634 Notes: BMI, body mass index; M group, Modified group; T group, Traditional group. *The continuous values are presented as means ± standard deviations with ranges and categorical values as numbers and percentages. 3.2 Comparison of pain VAS scores before and after surgery between the two groups of patients Comparison and analysis of pain VAS scores (See Table 2 .) of the two groups of patients, the results yielded that the patients in M group and T group, in the preoperative and postoperative 1 day pain VAS scores P-value is greater than 0.05, the difference does not exist statistically significant; in the postoperative 3 days, postoperative 7 days, postoperative 2 weeks P-value is less than 0.001, the The difference was statistically significant. Table 2 Comparison of knee pain VAS scores between the two groups of patients M group(n = 31) T group(n = 29) P-value preoperative 6.30 ± 0.86(5–9) 6.23 ± 0.80(5–8) 0.762 1 day postoperative 8.80 ± 0.65(7–10) 8.73 ± 0.68(7–10) 0.705 3 day postoperative 5.10 ± 0.79(4–7) 6.40 ± 0.66(5–8) <0.001 * 7 day postoperative 2.56 ± 0.76(3–5) 3.83 ± 0.90(3–6) <0.001 * 2 week postoperative 0.93 ± 0.86(0–3) 2.37 ± 0.92(0–5) <0.001 * Notes: VAS, The visual analog scale scores. p values of < 0.05 were considered significant (marked as asterisk, “*”) 3.3 Comparison of HSS scores before and after surgery between the two groups Comparison and analysis of HSS scores of knee joints of the two groups of patients, and the results yielded that the P-value of HSS scores(See Table 3 .) of the patients of the two groups in the preoperative period, 7 days after the operation, 2 weeks after the operation, and 1 month after the operation was greater than 0.05, and the difference was not statistically significant. Table 3 Comparison of HSS scores of knee joints in two groups of patients M group(n = 31) T group(n = 29) P-value preoperative 42.05 ± 5.77(37–56) 42.17 ± 5.33(39–60) 0.927 7 day postoperative 47.83 ± 3.51(45–60) 47.13 ± 2.66(43–61) 0.395 2 week postoperative 60.27 ± 3.36(51–67) 60.13 ± 3.53(53–68) 0.883 1 month postoperative 78.33 ± 3.05(71–85) 78.17 ± 3.16(69–86) 0.839 Notes: HSS, Hospital for Special Surgery Knee Score. 3.4 Comparison of the area of numbness AON before and after surgery in two groups of patients Comparison and analysis of the area of numbness AON before and after surgery in the two groups of patients, the p-value of the two groups of patients in the two weeks after surgery, one month after surgery, three months after surgery, half a year after surgery and one year after surgery were less than 0.001, and the difference was statistically significant (see Table 4 ). And it can be seen that the area of postoperative numbness in both groups of patients is shrinking over time, and some patients can even return to normal completely. Table 4 Comparison of the area of numbness AON (cm2) between the two groups of patients before and after surgery M group(n = 31) T group(n = 29) P-value 2 weeks postoperative 24.42 ± 3.52(16.34–31.32) 41.27 ± 4.81(36.32–56.43) <0.001 * 1 month postoperative 13.36 ± 4.79(3.54–20.56) 27.79 ± 8.27(12.36–44.06) <0.001 * 3 month postoperative 7.07 ± 3.71(0-12.44) 16.73 ± 6.66(0-30.77) <0.001 * 6 month postoperative 3.41 ± 2.60(0-8.12) 8.62 ± 4.36(0-17.63) <0.001 * 1 year postoperative 1.01 ± 1.54(0-6.61) 2.64 ± 1.81(0-9.36) <0.001 * AON: the area of numbness p values of < 0.05 were considered significant (marked as asterisk, “*”) 4. Discussion TKA is a widely accepted orthopedic procedure for the treatment of end-stage knee osteoarthritis, which can effectively reduce and eliminate pain, improve limb function and enhance quality of life, but most patients will develop postoperative skin sensory deficits on the lateral side of the incision, and there is no unanimity in the understanding of why this phenomenon occurs in the postoperative period, and there is no consensus on its prevention and treatment [ 9 – 11 ] . During surgery, most clinicians focus only on how the knee prosthesis is fitted, that the line of force should be good, and how well the soft tissue balance should be done, and assume that the surgery will be successful. However, for patients, unintentionally they find that the TKA produces numbness or paresthesia in front of the knee, and they feel very uncomfortable and may even think that the surgery has failed. Comprehensive literature reported that the lowest subjective sensation of numbness in patients after medial knee approach or medial parapatellar approach were 37% [ 12 ] or 55% [ 13 ] , and among these patients, about 2/3 of them did not complain of discomfort for anterior knee numbness, but still 1/3 of them complained of discomfort, and even when they were asked whether they agreed to do the other side of the knee again, the answer of this part of the patients was negative [ 14 ] . Peri-incisional sensory loss in total knee arthroplasty is frequently reported in patients and in the literature; however, the impact on clinical outcomes is unknown. It has been hypothesized that the lack of sensation around the total knee incision may lead to poor patient prognosis, difficulty with daily activities such as kneeling, and worse overall patient satisfaction [ 15 ][ 19 ] . That's why it makes sense to re-conceptualize anterior knee numbness after knee surgery. It is generally accepted that anterior knee sensation is innervated by the infrapatellar branch of the saphenous nerve, and that postoperative numbness and pain in the anterior skin of the knee is due to damage to the infrapatellar branch of the saphenous nerve [ 16 ] . Persistent postoperative pain originates from either intra- or extra-articular sources, and the cause of extra-articular pain is primarily a neuroma that forms after injury to the infrapatellar branch of the saphenous nerve, a lesser-known condition. The anatomy of the saphenous nerve shows that it originates from the posterior branch of the femoral nerve and divides into upper and lower branches at the medial end of the femur. In 60% of cases, the upper branch is the medial femoral cutaneous nerve, while the lower branch is the infrapatellar branch of the saphenous nerve in 100% of cases. In 80% of these cases, the nerve bundle of the infrapatellar branch crosses the tendon tissue from the medial side outward [ 18 ] . Therefore, during knee surgery, there is a high probability that the infrapatellar branch of the saphenogenic nerve will be injured, resulting in postoperative skin sensory deficits on the lateral side of the knee, producing neuromas and causing pain [ 20 ] . Tsukada et al [ 17 ] demonstrated that the anterolateral approach, compared with the traditional median parapatellar approach, can effectively reduce the extent of skin numbness on the lateral side of the knee, decrease the incidence of postoperative skin sensory deficits, and alleviate postoperative pain, thereby improving patient satisfaction. These findings suggest that using a protective technique for the infrapatellar branch of the saphenous nerve during TKA surgery is a feasible method to avoid or reduce the incidence of postoperative cutaneous sensory deficits on the lateral side of the incision. In our study, by understanding the anatomy and alignment of the saphenous nerve, we identified the saphenous nerve and its infrapatellar branch branches during TKA surgery, and protected them by the saphenous nerve protection technique, which resulted in a better solution to the problem of numbness and pain in the patients after surgery. The results of the study demonstrated that the extent of the area of numbness sensation in the modified surgical reveal incision, compared to the traditional surgical reveal incision, was smaller than in the traditional surgical incision for several postoperative periods. Patients tend not to experience numbness in the days following surgery in most patients, and, the area of numbness demonstrated is increasing in the 2 weeks following surgery, with a decrease in the area of numbness at 1 month following surgery compared to 2 weeks. Over time, patients' areas of numbness sensation are tending to decrease, and in some patients skin sensation can return to full normalization. Therefore, modified surgical techniques are feasible for decreasing numbness sensory deficits in the patient's knee and improving pain in the postoperative area. We also considered the sensation of numbness after TKA surgery, which should appear immediately after nerve damage. However, in the days following surgery, patients often do not exhibit numbness, and there is no specific range of numbness when stimulating the skin. We believe that postoperative pain may mask the numbness for a few days, but the exact mechanism underlying the delayed onset of numbness needs further exploration. With the advancement of surgical science and technology, the concepts of minimally invasive, rapid recovery, and increased patient comfort have been increasingly applied to orthopedics. We are constantly exploring new surgical approaches and challenging new techniques to meet our patients’ needs. Developing new techniques that preserve more anatomical structures is the key to addressing patients' real suffering and enhancing their perioperative comfort. In this context, it is crucial to complete the surgery without compromising the outcome and to preserve as many nerve fibers of the infrapatellar branch of the saphenous nerve as possible, thereby reducing postoperative skin numbness and pain. In this study, by improving the surgical incision and saphenous nerve protection technique, we aim to help more patients reduce surgical complications and improve their postoperative satisfaction. 5. Conclusion This randomized controlled trial demonstrates that the modified incision-exposure technique used in this study effectively protects the infrapatellar branch of the saphenous nerve without causing operational difficulties in osteotomy, ligament balancing, gap balancing, or prosthesis implantation during total knee replacements. This technique results in a smaller area of postoperative skin numbness compared to the traditional surgical method, with less postoperative pain and faster recovery. Declarations Acknowledgements Not applicable. Author contributions All authors contributed equally to this study. Zhi-Qiang Mao and Kai Li: Conceptualization, Methodology, Software, Investigation, Formal Analysis, Writing- Original Draft; Zhou Zhang and Ting Li: Data, Curation, Software, Visualization, Investigation; Jian-hua Lu, Meng-Qiang Fan, and Xiao-bing Chu: Visualization, Writing - Review & Editing. Funding This work was supported by Natural Science Foundation of China (Grant number 82305040), Zhejiang Province Leading Geese Plan (2024C03148), and Science and Technology Program of Traditional Chinese Medicine in Zhejiang Province (2025ZR028). Data availability Data cannot be provided due to identifying information of participants but is available from the corresponding author on reasonable request. Ethics approval and consent to participate Approval was received by the Ethics Committee of the first hospital of Zhejiang Chinese Medical University and obtained the unique identification number of research registration (2025-KS-228-01). Written informed consent for participation was obtained from all participants. All procedures were performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. Consent for publication Not applicable. Competing interests The authors declare no competing interests. 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Eur J Orthop Surg Traumatol. 2016;26:915–9. Kerver ALA, Leliveld MS, den Hartog D, et al. The surgical anatomy of the infrapatellar branch of the saphenous nerve in relation to incisions for anteromedial knee surgery[J]. JBJS. 2013;95(23):2119–25. Tsukada S, Kurosaka K, Nishino M, et al. Cutaneous hypesthesia and kneeling ability after total knee arthroplasty: a randomized controlled trial comparing anterolateral and anteromedial skin incision[J]. J Arthroplast. 2018;33(10):3174–80. Lee SR, Dahlgren NJP, Staggers JR, et al. Cadaveric study of the infrapatellar branch of the saphenous nerve: Can damage be prevented in total knee arthroplasty?[J]. J Clin Orthop trauma. 2019;10(2):274–7. Jariwala AC, Parthasarathy A, Kiran M, et al. Numbness around the total knee arthroplasty surgical scar: prevalence and effect on functional outcome[J]. J Arthroplast. 2017;32(7):2256–61. Bonnin MP, Basiglini L, Archbold HAP. What are the factors of residual pain after uncomplicated TKA?[J]. Volume 19. Arthroscopy: Knee Surgery, Sports Traumatology; 2011. pp. 1411–7. Younger J, McCue R, Mackey S. Pain outcomes: a brief review of instruments and techniques[J]. Curr Pain Headache Rep. 2009;13:39–43. Huang H, Tang K, Song X, et al. Effects of contralateral versus ipsilateral electroacupuncture for analgesia and rehabilitation after unilateral total knee arthroplasty: a randomized controlled trial[J]. Acupunct Med. 2024;42(4):183–93. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 14 Oct, 2025 Read the published version in BMC Musculoskeletal Disorders → Version 1 posted Editorial decision: Revision requested 12 May, 2025 Reviews received at journal 07 May, 2025 Reviews received at journal 05 May, 2025 Reviewers agreed at journal 29 Apr, 2025 Reviews received at journal 16 Apr, 2025 Reviews received at journal 15 Apr, 2025 Reviewers agreed at journal 05 Apr, 2025 Reviewers agreed at journal 04 Apr, 2025 Reviewers agreed at journal 04 Apr, 2025 Reviewers invited by journal 25 Mar, 2025 Submission checks completed at journal 24 Mar, 2025 First submitted to journal 24 Mar, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6057173","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":433850997,"identity":"47ad97a8-3696-41b7-ae70-a991c73da3d1","order_by":0,"name":"zhi qiang mao","email":"","orcid":"","institution":"The First Clinical College, Zhejiang Chinese Medical University","correspondingAuthor":false,"prefix":"","firstName":"zhi","middleName":"qiang","lastName":"mao","suffix":""},{"id":433850998,"identity":"1c123e04-2eb9-43d7-bd5c-66aeaf75a297","order_by":1,"name":"Kai Li","email":"","orcid":"","institution":"The First Clinical College, Zhejiang Chinese Medical University","correspondingAuthor":false,"prefix":"","firstName":"Kai","middleName":"","lastName":"Li","suffix":""},{"id":433850999,"identity":"2065db0d-132f-460d-b4f4-4cf34f4f227e","order_by":2,"name":"Zhou Zhang","email":"","orcid":"","institution":"Changxing County Hospital of Traditional Chinese Medicine","correspondingAuthor":false,"prefix":"","firstName":"Zhou","middleName":"","lastName":"Zhang","suffix":""},{"id":433851000,"identity":"3fb41489-7dd7-49ec-b193-2095261c89fc","order_by":3,"name":"Ting Li","email":"","orcid":"","institution":"Center for Plastic \u0026 Reconstructive Surgery, Department of Plastic \u0026 Reconstructive Surgery, Zhejiang Provincial People's Hospital (Affiliated People's Hospital, Hangzhou Medical College)","correspondingAuthor":false,"prefix":"","firstName":"Ting","middleName":"","lastName":"Li","suffix":""},{"id":433851001,"identity":"25ae9444-0ecb-4066-89f8-b9f5c0e46436","order_by":4,"name":"Jian-hua Lu","email":"","orcid":"","institution":"a Department of Orthopaedics, The First Affiliated Hospital of Zhejiang Chinese Medical University","correspondingAuthor":false,"prefix":"","firstName":"Jian-hua","middleName":"","lastName":"Lu","suffix":""},{"id":433851002,"identity":"7ec8b443-78da-4e4c-914e-84c45a311bd0","order_by":5,"name":"Meng-Qiang Fan","email":"","orcid":"","institution":"a Department of Orthopaedics, The First Affiliated Hospital of Zhejiang Chinese Medical University","correspondingAuthor":false,"prefix":"","firstName":"Meng-Qiang","middleName":"","lastName":"Fan","suffix":""},{"id":433851003,"identity":"c8de0e34-a4e7-414c-87fa-d8862ad03bea","order_by":6,"name":"Xiao-bing Chu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA4ElEQVRIie3PsWrDMBCA4TMHynJU6xlC+goKAYe8jbR4SqGjBkMTHOQhtHkVj9maINCk7B1d+gTdOnQomVsqd+ugb76fuwPIsn9ITA6D/1TNw3NbbAdtm3RyQ7EYyIain6BXQwzpZMZrVBSx6KWoy9cdjjiMLoFLJ3CJVFmzESC7vU788lTz3E3FqqXqxRynwPHSJ7acKjZOEPhrEgUovkskrCs+O+Rrcm8cjknWi/kmolJe1DAuoWDewAZdtuhZx0DJX2679uRBNVrK8/b9wzYz2T3+nnxDfxvPsizLfvQFc2BHLOKwdYYAAAAASUVORK5CYII=","orcid":"","institution":"a Department of Orthopaedics, The First Affiliated Hospital of Zhejiang Chinese Medical University","correspondingAuthor":true,"prefix":"","firstName":"Xiao-bing","middleName":"","lastName":"Chu","suffix":""}],"badges":[],"createdAt":"2025-02-18 14:38:29","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6057173/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6057173/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12891-025-09099-5","type":"published","date":"2025-10-14T15:57:39+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":79324284,"identity":"d8c9e129-bb40-4c7e-8a7f-05bc5ce9fdc5","added_by":"auto","created_at":"2025-03-27 05:09:48","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":478153,"visible":true,"origin":"","legend":"\u003cp\u003ea and b shows an intraoperative picture of the modified surgical technique\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6057173/v1/1633c227d1dee99d04785454.png"},{"id":79324291,"identity":"a9951184-9ef5-44a8-b450-3eb9ea5cb7af","added_by":"auto","created_at":"2025-03-27 05:09:48","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":490991,"visible":true,"origin":"","legend":"\u003cp\u003eThe surgical incision and the lower edges of the medial and lateral knee eyes are marked with a marker pen to determine the level of the knee joint line.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6057173/v1/aeced62430a6021b30d300de.png"},{"id":79324265,"identity":"9cc5e399-2223-4a72-a6d0-087b718f8efa","added_by":"auto","created_at":"2025-03-27 05:09:47","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":449071,"visible":true,"origin":"","legend":"\u003cp\u003ea, b, c, and d both show the extent of numbness 2 weeks postoperatively after modified surgical access. (Fig a and b represent the same patient, as do Fig c and d).\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6057173/v1/e97ca5ba9b5e891b3f6af772.png"},{"id":79326286,"identity":"c1186243-2668-4048-a521-8f6b09e36b85","added_by":"auto","created_at":"2025-03-27 05:34:39","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":370293,"visible":true,"origin":"","legend":"\u003cp\u003ea, b, c, and d both show the extent of numbness 2 weeks postoperatively after the traditional surgical approach. (Fig a and b represent the same patient, as do Fig c and d)\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6057173/v1/9c33ffdc15274351a6d63f85.png"},{"id":79326290,"identity":"c08c45fc-a541-44b3-bbdd-8017b2a78a7f","added_by":"auto","created_at":"2025-03-27 05:34:40","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":43629,"visible":true,"origin":"","legend":"\u003cp\u003eFlow diagram of patient enrollment\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-6057173/v1/37d141d83eb29f4803a092bb.png"},{"id":93955989,"identity":"da260fa4-9e4a-4599-b340-729b5be54fbe","added_by":"auto","created_at":"2025-10-20 16:08:54","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3409394,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6057173/v1/cdf6d4eb-d1e4-4f4e-8fd1-799aafb89d44.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Application of saphenous nerve infrapatellar branch protection technique in total knee arthroplasty","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eKnee Osteoarthritis (KOA) is a common degenerative joint disease whose incidence significantly increases with age. Typical symptoms include joint pain, limited mobility, and in severe cases, joint deformity or even disability. These symptoms not only causes pain, but also jeopardize health and affects the quality of life\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e. Total Knee Arthroplasty (TKA) is currently the treatment of choice for end-stage knee osteoarthritis. Studies have found that the 10-year survival rate of patients after TKA has exceeded 90%\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e. With the increasing elderly population in China, the number of KOA patients with receiving TKA is also rising. As people's cognitive concepts and living standards improve, patients' expectations for postoperative outcomes are also increasing. Despite recent advancements in TKA surgery, studies have shown that while over 80% of patients are satisfied with their new joints, approximately 20% remain dissatisfied\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e. Postoperative pain is a potential contributing factor to this dissatisfaction. Beswick et al\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e reported that 10\u0026ndash;34% of post-TKA patients experience moderate to severe pain, leading to dissatisfaction. Postoperative lateral knee cutaneous dysesthesia may also be a contributing factor, with Macdonald\u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e et al reporting an incidence of lateral knee numbness ranging from 37\u0026ndash;100% after TKA. Tanavalee et al\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e reported an area of skin numbness (AON) of up to 51.7cm\u003csup\u003e2\u003c/sup\u003e two weeks after TKA, which gradually reduced to 2.1 cm\u0026sup2; after one year. The traditional TKA procedure, which involves a medial knee incision and a medial parapatellar approach, often damages the infrapatellar branch of the saphenous nerve distal to the incision. As a result, up to 100% of patients experience lateral knee skin numbness after knee arthroplasty as an unavoidable complication\u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e. This numbness lasts longer and is more painful in patients after TKA, and some patients do not achieve the expected therapeutic effect. Addressing these refractory numbness and pain symptoms is essential to improve patient satisfaction.\u003c/p\u003e \u003cp\u003eThere are no established techniques for protecting the saphenous nerve branches, either because surgeons have not paid enough attention to the adverse outcomes caused by nerve injury or because dissection and isolation of the nerve during surgery are time-consuming and laborious. However, our team has developed a technique that is both fast and effective in protecting the infrapatellar branch of the saphenous nerve. A study of patients who underwent a modified TKA procedure found less subjective numbness and pain in the operative area, with good efficacy. Therefore, this study aims to compare and analyze the postoperative numbness and pain between patients who underwent modified and traditional surgical techniques, to evaluate the effect of modified surgery on postoperative numbness and pain, and to provide new insights for clinical practice.\u003c/p\u003e"},{"header":"2. Materials and methods","content":"\u003cp\u003e\u003cstrong\u003e2.1 Study design\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study protocol was reviewed and approved by the Ethics Committee of the First Affiliated Hospital of Zhejiang University of Traditional Chinese Medicine, and obtained the unique identification number of research registration (2025-KS-228-01). Written informed consent for participation was obtained from all participants. All procedures were performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2 Study population\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn this study, 68 patients who underwent TKA for the first time at Zhejiang Provincial Hospital of Traditional Chinese Medicine between January 2022 and June 2023 were selected and randomly divided into\u0026nbsp;Modified group (M group)\u0026nbsp;and Traditional group (T group), with 34 patients in each group.\u0026nbsp;Inclusion criteria and exclusion criteria are as follows:\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInclusion criteria:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ea. The patient had her first unilateral total knee replacement.\u003c/p\u003e\n\u003cp\u003eb. There was no previous history of periprosthetic knee surgery.\u003c/p\u003e\n\u003cp\u003ec. Preoperative skin sensation was normal in both knees.\u003c/p\u003e\n\u003cp\u003ed. No peripheral or central nervous system disease.\u003c/p\u003e\n\u003cp\u003ee. Ability to cooperate with the physician\u0026apos;s physical examination and complete questions and answers.\u003c/p\u003e\n\u003cp\u003ef. Informed consent for treatment and trial protocol.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eExclusion criteria:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ea. Postoperative infections and revision.\u003c/p\u003e\n\u003cp\u003eb Preoperative skin sensory deficits in the affected knee.\u003c/p\u003e\n\u003cp\u003ec. The patient has peripheral neuropathy and central nervous system abnormalities.\u003c/p\u003e\n\u003cp\u003ed. Unable to determine efficacy, lost to follow-up and incomplete information.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3 Randomization\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe participants were randomly assigned to either the experimental group or the control group using a computer-generated randomization sequence. To ensure allocation concealment, the randomization list was prepared by an independent statistician who was not involved in the recruitment or treatment processes. The allocation sequence was stored in sealed, opaque envelopes, which were opened only after the participants had completed the baseline assessments and provided informed consent. This method ensured that both the researchers and participants were blinded to group assignment until the intervention began. The randomization ratio was 1:1, with an equal number of participants allocated to each group. This approach minimized selection bias and ensured the comparability of the two groups at baseline.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.4 Methods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn M group, the articular cavity was opened and exposed using a modified method. The skin incision was the same length as that in the classical median knee surgery, and the exposure of the articular cavity was performed in two steps. The first step was similar to the classical medial parapatellar approach above the knee joint line, but the proximal end was extended proximally along the medial femoral tendon to relax the knee-extension device, In the second step, the proximal incision was retracted laterally, and the skin below the joint line was cut longitudinally while maintaining skin tension to protect all subcutaneous soft tissue in the superficial layer of the patellar tendon, which contains the infrapatellar branch of the saphenous nerve (\u003cstrong\u003eFig\u0026nbsp;1\u003c/strong\u003e). In T group, the joint cavity was exposed using the traditonal medial parapatellar approach. All 68 TKA surgeries were performed by the same attending surgeon, and the same brand of knee prosthesis was used (no patellar surface replacement, only patellofemoral plasty). The preoperative and postoperative skin sensation around the incision was statistically observed in both groups, including the size and changes in the distribution area of skin numbness. A comparative analysis was conducted to determine the differences in anterolateral knee joint numbness and pain between the two surgical techniques. The gender, age, height, weight, affected side, operative time, surgical bleeding, length of surgical incision, VAS(visual analog scale) score, and HSS(Hospital for Special Surgery) knee score of patients in both groups were recorded separately.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.5 Surgical Procedures\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003epreoperative preparation\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe patients were assessed for the degree of internal and external knee deformity, knee mobility, pain VAS score\u003csup\u003e[21]\u003c/sup\u003e, HSS score\u003csup\u003e[22]\u003c/sup\u003e, and underwent improved preoperative related examinations, such as full-length standing radiographs of both lower limbs, to assess the risk of surgery.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSurgical steps\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAfter successful general anesthesia, the patient was placed in the supine position. The level of the knee joint line was determined using the lower edges of the medial and lateral knee eyes as markers, and this was marked with a marker pen (\u003cstrong\u003eFig 2\u003c/strong\u003e). After driving the blood out with a tourniquet, the affected limb was routinely disinfected and draped. A longitudinal incision was made in the middle of the anterior knee, extending from 3 cm proximal to the upper edge of the patella to the medial end of the tibial tuberosity distally. The incision was revealed in Two steps: First, above the joint line level, a conventional medial parapatellar incision was used to expose the joint cavity. Then, using a retractor, the incision was pulled to both sides to cut the skin below the joint line under tension, while retaining the patellar tendon in the superficial layer of the soft tissues (which contains the infrapatellar branch of the saphenous nerve). To increase the laxity of the knee-extension device, the quadriceps tendon could be incised proximally to the extent necessary to turn the patella. Residual meniscus, and the anterior cruciate ligament were removed. The knee was positioned in flexion, and the medial and lateral collateral ligaments were protected. Distal femoral osteotomy was performed after intramedullary positioning of the femur. The prosthesis was selected with a 5-7 degree valgus alignment. A \u0026ldquo;four-in-one\u0026rdquo; osteotomy guide was used for the femoral condyles, and for the PS prosthesis, additional intercondylar osteotomy was performed for the upper and lower beveled cuts. The femoral prosthesis specimen was tested and mounted. The tibial osteotomy mold was tested to determine the size of the tibial prosthesis. Tibial osteotomy was performed, and the rotational alignment of the tibial prosthesis and the appropriate type were determined. The proximal tibial bone bed was prepared, the specimen was removed, and the knee was tested for equal flexion or extension clearance and correct lower extremity alignment. The bone surface was repeatedly rinsed with a high-pressure pulse lavage gun, dried, and bone cement was mixed. All prostheses were installed and fixed in the dough stage. The spacer was measured and installed. The patellar articular surface was trimmed and shaped with bone biting forceps. The patellar tracking was checked to ensure good knee flexion or extension mobility and joint stability. The tourniquet was released to stop bleeding, and bleeding points were treated with electrocautery. The corresponding tissues were sutured layer by layer, and the wound was wrapped with a cotton-padded bandage under pressure. The operation was then completed.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePreoperative and intraoperative\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003etreatment\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe physician instructed the patient to use Bactrim ointment and chlorhexidine to disinfect the skin before surgery. Patients in both groups were administered 2 g of cefazolin sodium during preoperative induction of anesthesia, 40 g of bone cement mixed with 1,000 mg of vancomycin intraoperatively to prevent infection, and 1 g of tranexamic acid to reduce bleeding.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePost-operative treatment\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBoth groups of patients received postoperative intensive care, including nasal cannula oxygen and continuous monitoring of vital signs. Symptomatic treatments were provided, such as gastric protection, analgesia, antiemetics, neurotrophic support and nutritional support. Additionally, nebulization therapy was administered to improve ventilation and other symptomatic treatments were given as needed.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.6 Observation indicators\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSkin sensory conditions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe skin sensation around the incision of the affected knee was observed in both groups before surgery, and at 14 days, 1 month, 3 months, 6 months, and 1 year postoperative. This included whether the skin on the lateral side of the surgical incision felt numb after surgery, as well as the size and change of the numbness area (the area of numbness of the skin (AON) was measured in cm\u003csup\u003e2\u003c/sup\u003e)\u003csup\u003e[7]\u003c/sup\u003e. Specific measurements were taken as follows: First, a sterile cotton swab was lightly touched on the outer side of the incision to determine if sensation was present and if numbness was felt, thereby identifying the approximate range of sensory abnormality. Then, tests were conducted in an outward-to-inward and top-to-bottom order, with a double-knee comparison to identify specific areas of abnormal sensation. The extent of the numbness was drawn with a marker pen, and the size of the area was measured using a ruler (see \u003cstrong\u003eFig 3 and Fig 4\u003c/strong\u003e). Regular postoperative follow-ups were performed to observe whether the numbness improved and whether the area of numbness decreased.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.7 Clinical efficacy evaluation\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e1）The pain scores of the patients in both groups were observed and evaluated preoperatively, and on postoperative days 1, 3, 7, and 14 using the Visual Analog Scale (VAS)\u003csup\u003e[21]\u003c/sup\u003e. The VAS was administered as follows: A horizontal line was drawn on a piece of paper, divided into 11 equal intervals labeled \u0026ldquo;0\u0026rdquo; to \u0026ldquo;10\u0026rdquo;. \u0026ldquo;0\u0026rdquo; indicates no pain, while \u0026ldquo;10\u0026rdquo; indicates extremely painful and intolerable pain. Patients were asked to mark their pain level on the line according to their subjective feelings.\u003c/p\u003e\n\u003cp\u003e2）The HSS scores\u003csup\u003e[22]\u003c/sup\u003e\u003csup\u003e\u0026nbsp;\u003c/sup\u003eof patients in both groups were observed preoperatively, and on postoperative day 1, 7, and 14, as well as at month 1 postoperatively. The scores were evaluated according to the Hospital for Special Surgery (HSS) scoring system, which includes seven main aspects: pain, function, range of motion, muscle strength, flexion contracture, extension lag, and stability. Patients were able to assess their affected knee joints based on the criteria for each item.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.8 Sample size\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe sample size was calculated using G * Power (http://www.gpower.hhu.de/) power analysis. We used a two-tailed matched-pairs t test with the following settings, and our primary outcome measure had an effect size of 0.74, a significance level (alpha) of 0.05, and a power of 0.80. Based on these criteria, a sample size of 30 patients was required for both groups. Finally, to compensate for the potential loss of follow-up, we enrolled a total of 68 patients.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.9 Statistical analysis\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData analysis was performed using SPSS 26.0 statistical software. Due to the relatively small sample size, the Shapiro\u0026ndash;Wilk test was applied to test the normality of data distributions. Normally distributed data were expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD, and group comparisons were performed using independent samples t-test. Categorical variables were analyzed using Pearson\u0026rsquo;s chi-square. Based on these test results, we selected appropriate parametric or non-parametric statistical tests.\u003c/p\u003e"},{"header":"3. Result","content":"\u003cp\u003eIn this randomized clinical trial, 68 patients scheduled for total knee arthroplasty were initially enrolled. After applying the exclusion criteria, 8 patients were excluded from the study, including 1 patient who was unable to comply with measurements, 4 patients who withdrew during the study, and 3 patients who were lost to follow-up postoperatively. Ultimately, 60 patients were included in the final analysis, as shown in the Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Comparison of general information\u003c/h2\u003e \u003cp\u003eBy statistically analyzing the basic data of the two groups of patients. The p-values for affected side, gender, age, BMI, length of surgical incision, surgical time, and intraoperative hemorrhage were all greater than 0.05, indicating no statistically significant differences. See Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBasic data of the two groups of patients\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eM group(n\u0026thinsp;=\u0026thinsp;31)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eT group(n\u0026thinsp;=\u0026thinsp;29)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP-value\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge(years)*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e67.20\u0026thinsp;\u0026plusmn;\u0026thinsp;4.28(62\u0026ndash;81)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e66.90\u0026thinsp;\u0026plusmn;\u0026thinsp;4.07(61\u0026ndash;79)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.785\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI(Kg/㎡)*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e23.06\u0026thinsp;\u0026plusmn;\u0026thinsp;1.48(21.5\u0026ndash;26.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23.17\u0026thinsp;\u0026plusmn;\u0026thinsp;1.45(21.37\u0026ndash;26.41)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.765\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex(male / female)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16(53.3%)/15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e17(58.6%)/12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.791\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLength of surgical incision(cm)*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15.28\u0026thinsp;\u0026plusmn;\u0026thinsp;0.93(14\u0026ndash;17)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15.17\u0026thinsp;\u0026plusmn;\u0026thinsp;0.89(14\u0026ndash;17)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.678\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSurgical time(min)*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e80\u0026thinsp;\u0026plusmn;\u0026thinsp;15.05(75\u0026ndash;104)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e83\u0026thinsp;\u0026plusmn;\u0026thinsp;14.75(71\u0026ndash;106)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.596\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIntraoperative bleeding(ml)*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e112.17\u0026thinsp;\u0026plusmn;\u0026thinsp;18.15(80\u0026ndash;150)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e110.84\u0026thinsp;\u0026plusmn;\u0026thinsp;19.63(90\u0026ndash;150)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.634\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eNotes: BMI, body mass index; M group, Modified group; T group, Traditional group.\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003e*The continuous values are presented as means\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviations with ranges and categorical values as numbers and percentages.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Comparison of pain VAS scores before and after surgery between the two groups of patients\u003c/h2\u003e \u003cp\u003eComparison and analysis of pain VAS scores (See Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.) of the two groups of patients, the results yielded that the patients in M group and T group, in the preoperative and postoperative 1 day pain VAS scores P-value is greater than 0.05, the difference does not exist statistically significant; in the postoperative 3 days, postoperative 7 days, postoperative 2 weeks P-value is less than 0.001, the The difference was statistically significant.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of knee pain VAS scores between the two groups of patients\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eM group(n\u0026thinsp;=\u0026thinsp;31)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eT group(n\u0026thinsp;=\u0026thinsp;29)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP-value\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epreoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e6.30\u0026thinsp;\u0026plusmn;\u0026thinsp;0.86(5\u0026ndash;9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e6.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.80(5\u0026ndash;8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.762\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1 day postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e8.80\u0026thinsp;\u0026plusmn;\u0026thinsp;0.65(7\u0026ndash;10)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e8.73\u0026thinsp;\u0026plusmn;\u0026thinsp;0.68(7\u0026ndash;10)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.705\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3 day postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e5.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.79(4\u0026ndash;7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e6.40\u0026thinsp;\u0026plusmn;\u0026thinsp;0.66(5\u0026ndash;8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7 day postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e2.56\u0026thinsp;\u0026plusmn;\u0026thinsp;0.76(3\u0026ndash;5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e3.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.90(3\u0026ndash;6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2 week postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.93\u0026thinsp;\u0026plusmn;\u0026thinsp;0.86(0\u0026ndash;3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e2.37\u0026thinsp;\u0026plusmn;\u0026thinsp;0.92(0\u0026ndash;5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eNotes: VAS, The visual analog scale scores.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003ep values of \u0026lt;\u0026thinsp;0.05 were considered significant (marked as asterisk, \u0026ldquo;*\u0026rdquo;)\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Comparison of HSS scores before and after surgery between the two groups\u003c/h2\u003e \u003cp\u003eComparison and analysis of HSS scores of knee joints of the two groups of patients, and the results yielded that the P-value of HSS scores(See Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.) of the patients of the two groups in the preoperative period, 7 days after the operation, 2 weeks after the operation, and 1 month after the operation was greater than 0.05, and the difference was not statistically significant.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of HSS scores of knee joints in two groups of patients\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eM group(n\u0026thinsp;=\u0026thinsp;31)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eT group(n\u0026thinsp;=\u0026thinsp;29)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP-value\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epreoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e42.05\u0026thinsp;\u0026plusmn;\u0026thinsp;5.77(37\u0026ndash;56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e42.17\u0026thinsp;\u0026plusmn;\u0026thinsp;5.33(39\u0026ndash;60)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.927\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7 day postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e47.83\u0026thinsp;\u0026plusmn;\u0026thinsp;3.51(45\u0026ndash;60)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e47.13\u0026thinsp;\u0026plusmn;\u0026thinsp;2.66(43\u0026ndash;61)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.395\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2 week postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e60.27\u0026thinsp;\u0026plusmn;\u0026thinsp;3.36(51\u0026ndash;67)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e60.13\u0026thinsp;\u0026plusmn;\u0026thinsp;3.53(53\u0026ndash;68)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.883\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1 month postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e78.33\u0026thinsp;\u0026plusmn;\u0026thinsp;3.05(71\u0026ndash;85)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e78.17\u0026thinsp;\u0026plusmn;\u0026thinsp;3.16(69\u0026ndash;86)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.839\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eNotes: HSS, Hospital for Special Surgery Knee Score.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003e3.4 Comparison of the area of numbness AON before and after surgery in two groups of patients\u003c/b\u003e \u003c/p\u003e \u003cp\u003eComparison and analysis of the area of numbness AON before and after surgery in the two groups of patients, the p-value of the two groups of patients in the two weeks after surgery, one month after surgery, three months after surgery, half a year after surgery and one year after surgery were less than 0.001, and the difference was statistically significant (see Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). And it can be seen that the area of postoperative numbness in both groups of patients is shrinking over time, and some patients can even return to normal completely.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of the area of numbness AON (cm2) between the two groups of patients before and after surgery\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eM group(n\u0026thinsp;=\u0026thinsp;31)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eT group(n\u0026thinsp;=\u0026thinsp;29)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP-value\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2 weeks postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e24.42\u0026thinsp;\u0026plusmn;\u0026thinsp;3.52(16.34\u0026ndash;31.32)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e41.27\u0026thinsp;\u0026plusmn;\u0026thinsp;4.81(36.32\u0026ndash;56.43)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1 month postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e13.36\u0026thinsp;\u0026plusmn;\u0026thinsp;4.79(3.54\u0026ndash;20.56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e27.79\u0026thinsp;\u0026plusmn;\u0026thinsp;8.27(12.36\u0026ndash;44.06)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3 month postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e7.07\u0026thinsp;\u0026plusmn;\u0026thinsp;3.71(0-12.44)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e16.73\u0026thinsp;\u0026plusmn;\u0026thinsp;6.66(0-30.77)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6 month postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e3.41\u0026thinsp;\u0026plusmn;\u0026thinsp;2.60(0-8.12)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e8.62\u0026thinsp;\u0026plusmn;\u0026thinsp;4.36(0-17.63)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1 year postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e1.01\u0026thinsp;\u0026plusmn;\u0026thinsp;1.54(0-6.61)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e2.64\u0026thinsp;\u0026plusmn;\u0026thinsp;1.81(0-9.36)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eAON: the area of numbness\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cem\u003ep values\u003c/em\u003e of \u0026lt;\u0026thinsp;0.05 were considered significant (marked as asterisk, \u0026ldquo;*\u0026rdquo;)\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eTKA is a widely accepted orthopedic procedure for the treatment of end-stage knee osteoarthritis, which can effectively reduce and eliminate pain, improve limb function and enhance quality of life, but most patients will develop postoperative skin sensory deficits on the lateral side of the incision, and there is no unanimity in the understanding of why this phenomenon occurs in the postoperative period, and there is no consensus on its prevention and treatment\u003csup\u003e[\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e. During surgery, most clinicians focus only on how the knee prosthesis is fitted, that the line of force should be good, and how well the soft tissue balance should be done, and assume that the surgery will be successful. However, for patients, unintentionally they find that the TKA produces numbness or paresthesia in front of the knee, and they feel very uncomfortable and may even think that the surgery has failed. Comprehensive literature reported that the lowest subjective sensation of numbness in patients after medial knee approach or medial parapatellar approach were 37%\u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e or 55%\u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e, and among these patients, about 2/3 of them did not complain of discomfort for anterior knee numbness, but still 1/3 of them complained of discomfort, and even when they were asked whether they agreed to do the other side of the knee again, the answer of this part of the patients was negative\u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003ePeri-incisional sensory loss in total knee arthroplasty is frequently reported in patients and in the literature; however, the impact on clinical outcomes is unknown. It has been hypothesized that the lack of sensation around the total knee incision may lead to poor patient prognosis, difficulty with daily activities such as kneeling, and worse overall patient satisfaction\u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e][\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e. That's why it makes sense to re-conceptualize anterior knee numbness after knee surgery. It is generally accepted that anterior knee sensation is innervated by the infrapatellar branch of the saphenous nerve, and that postoperative numbness and pain in the anterior skin of the knee is due to damage to the infrapatellar branch of the saphenous nerve\u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e. Persistent postoperative pain originates from either intra- or extra-articular sources, and the cause of extra-articular pain is primarily a neuroma that forms after injury to the infrapatellar branch of the saphenous nerve, a lesser-known condition.\u003c/p\u003e \u003cp\u003eThe anatomy of the saphenous nerve shows that it originates from the posterior branch of the femoral nerve and divides into upper and lower branches at the medial end of the femur. In 60% of cases, the upper branch is the medial femoral cutaneous nerve, while the lower branch is the infrapatellar branch of the saphenous nerve in 100% of cases. In 80% of these cases, the nerve bundle of the infrapatellar branch crosses the tendon tissue from the medial side outward\u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e. Therefore, during knee surgery, there is a high probability that the infrapatellar branch of the saphenogenic nerve will be injured, resulting in postoperative skin sensory deficits on the lateral side of the knee, producing neuromas and causing pain\u003csup\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e. Tsukada et al\u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e demonstrated that the anterolateral approach, compared with the traditional median parapatellar approach, can effectively reduce the extent of skin numbness on the lateral side of the knee, decrease the incidence of postoperative skin sensory deficits, and alleviate postoperative pain, thereby improving patient satisfaction. These findings suggest that using a protective technique for the infrapatellar branch of the saphenous nerve during TKA surgery is a feasible method to avoid or reduce the incidence of postoperative cutaneous sensory deficits on the lateral side of the incision.\u003c/p\u003e \u003cp\u003eIn our study, by understanding the anatomy and alignment of the saphenous nerve, we identified the saphenous nerve and its infrapatellar branch branches during TKA surgery, and protected them by the saphenous nerve protection technique, which resulted in a better solution to the problem of numbness and pain in the patients after surgery. The results of the study demonstrated that the extent of the area of numbness sensation in the modified surgical reveal incision, compared to the traditional surgical reveal incision, was smaller than in the traditional surgical incision for several postoperative periods. Patients tend not to experience numbness in the days following surgery in most patients, and, the area of numbness demonstrated is increasing in the 2 weeks following surgery, with a decrease in the area of numbness at 1 month following surgery compared to 2 weeks. Over time, patients' areas of numbness sensation are tending to decrease, and in some patients skin sensation can return to full normalization. Therefore, modified surgical techniques are feasible for decreasing numbness sensory deficits in the patient's knee and improving pain in the postoperative area.\u003c/p\u003e \u003cp\u003eWe also considered the sensation of numbness after TKA surgery, which should appear immediately after nerve damage. However, in the days following surgery, patients often do not exhibit numbness, and there is no specific range of numbness when stimulating the skin. We believe that postoperative pain may mask the numbness for a few days, but the exact mechanism underlying the delayed onset of numbness needs further exploration. With the advancement of surgical science and technology, the concepts of minimally invasive, rapid recovery, and increased patient comfort have been increasingly applied to orthopedics. We are constantly exploring new surgical approaches and challenging new techniques to meet our patients\u0026rsquo; needs. Developing new techniques that preserve more anatomical structures is the key to addressing patients' real suffering and enhancing their perioperative comfort. In this context, it is crucial to complete the surgery without compromising the outcome and to preserve as many nerve fibers of the infrapatellar branch of the saphenous nerve as possible, thereby reducing postoperative skin numbness and pain. In this study, by improving the surgical incision and saphenous nerve protection technique, we aim to help more patients reduce surgical complications and improve their postoperative satisfaction.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eThis randomized controlled trial demonstrates that the modified incision-exposure technique used in this study effectively protects the infrapatellar branch of the saphenous nerve without causing operational difficulties in osteotomy, ligament balancing, gap balancing, or prosthesis implantation during total knee replacements. This technique results in a smaller area of postoperative skin numbness compared to the traditional surgical method, with less postoperative pain and faster recovery.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAcknowledgements\u003c/h2\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003ch2\u003eAuthor contributions\u003c/h2\u003e\n\u003cp\u003eAll authors contributed equally to this study.\u003c/p\u003e\n\u003cp\u003eZhi-Qiang Mao and Kai Li: Conceptualization, Methodology, Software, Investigation, Formal Analysis, Writing- Original Draft; Zhou Zhang and Ting Li: Data, Curation, Software, Visualization, Investigation; Jian-hua Lu, Meng-Qiang Fan, and Xiao-bing Chu: Visualization, Writing - Review \u0026amp; Editing.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThis work was supported by Natural Science Foundation of China (Grant number 82305040), Zhejiang Province Leading Geese Plan (2024C03148), and Science and Technology Program of Traditional Chinese Medicine in Zhejiang Province (2025ZR028).\u003c/p\u003e\n\u003ch2\u003eData availability\u003c/h2\u003e\n\u003cp\u003eData cannot be provided due to identifying information of participants but is available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003ch3\u003eEthics approval and consent to participate\u003c/h3\u003e\n\u003cp\u003eApproval was received by the Ethics Committee of the first hospital of Zhejiang Chinese Medical University and obtained the unique identification number of research registration (2025-KS-228-01). Written informed consent for participation was obtained from all participants. All procedures were performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments.\u003c/p\u003e\n\u003ch3\u003eConsent for publication\u003c/h3\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003ch3\u003eCompeting interests\u003c/h3\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eO\u0026rsquo;Neill TW, Felson DT. Mechanisms of osteoarthritis (OA) pain[J]. Curr Osteoporos Rep. 2018;16:611\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi HZ, Liang XZ, Sun YQ, et al. Global, regional, and national burdens of osteoarthritis from 1990 to 2021: findings from the 2021 global burden of disease study[J]. Front Med. 2024;11:1476853.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWillinger ML, Heimroth J, Sodhi N, et al. Management of refractory pain after total joint replacement[J]. Curr Pain Headache Rep. 2021;25:1\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBourne RB, Chesworth BM, Davis AM, et al. Patient satisfaction after total knee arthroplasty: who is satisfied and who is not?[J]. Clin Orthop Relat Research\u0026reg;. 2010;468(1):57\u0026ndash;63.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBeswick AD, Wylde V, Gooberman-Hill R, et al. What proportion of patients report long-term pain after total hip or knee replacement for osteoarthritis? A systematic review of prospective studies in unselected patients[J]. BMJ open. 2012;2(1):e000435.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMacDonald B, Kurdin A, Somerville L, et al. The effect of sensory deficit after total knee arthroplasty on patient satisfaction and kneeling ability[J]. Arthroplasty Today. 2021;7:264\u0026ndash;7. e2.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTanavalee A, Limtrakul A, Veerasethsiri P, et al. Area of skin numbness after total knee arthroplasty: does minimally invasive approach make any difference from standard approach?[J]. J Arthroplast. 2016;31(11):2499\u0026ndash;503.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRuangsomboon P, Nepal S, Udomkiat P, et al. No effect of oral mecobalamin on skin numbness at 3 months after total knee arthroplasty: a randomized, double-blinded, placebo-controlled superiority trial[J]. JBJS Open Access. 2022;7(2):e22.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eManiar RN, Singhi T, Nanivadekar A, et al. A prospective randomized study in 20 patients undergoing bilateral TKA comparing midline incision to anterolateral incision[J]. J Orthop Traumatol. 2017;18:325\u0026ndash;33.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDonaldson DQ, Torkington M, Anthony IC, et al. Influence of skin incision position on physiological and biochemical changes in tissue after primary total knee replacement\u0026ndash;A prospective randomised controlled trial[J]. BMC Surg. 2015;15:1\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStav A, Reytman L, Sevi R et al. Femoral versus multiple nerve blocks for analgesia after total knee arthroplasty[J]. Rambam Maimonides Med J, 2017, 8(1).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHopton BP, Tommichan MC, Howell FR. Reducing lateral skin flap numbness after total knee arthroplasty[J]. Knee. 2004;11(4):289\u0026ndash;91.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSundaram RO, Ramakrishnan M, Harvey RA, et al. Comparison of scars and resulting hypoaesthesia between the medial parapatellar and midline skin incisions in total knee arthroplasty[J]. Knee. 2007;14(5):375\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBlack R, Green C, Sochart D. Postoperative numbness of the knee following total knee arthroplasty[J]. Annals Royal Coll Surg Engl. 2013;95(8):565\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCalvert N, Milne L, Kuster M. A comparison of kneeling ability after lateral or midline incisions in total knee arthroplasty[J]. Eur J Orthop Surg Traumatol. 2016;26:915\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKerver ALA, Leliveld MS, den Hartog D, et al. The surgical anatomy of the infrapatellar branch of the saphenous nerve in relation to incisions for anteromedial knee surgery[J]. JBJS. 2013;95(23):2119\u0026ndash;25.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTsukada S, Kurosaka K, Nishino M, et al. Cutaneous hypesthesia and kneeling ability after total knee arthroplasty: a randomized controlled trial comparing anterolateral and anteromedial skin incision[J]. J Arthroplast. 2018;33(10):3174\u0026ndash;80.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLee SR, Dahlgren NJP, Staggers JR, et al. Cadaveric study of the infrapatellar branch of the saphenous nerve: Can damage be prevented in total knee arthroplasty?[J]. J Clin Orthop trauma. 2019;10(2):274\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJariwala AC, Parthasarathy A, Kiran M, et al. Numbness around the total knee arthroplasty surgical scar: prevalence and effect on functional outcome[J]. J Arthroplast. 2017;32(7):2256\u0026ndash;61.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBonnin MP, Basiglini L, Archbold HAP. What are the factors of residual pain after uncomplicated TKA?[J]. Volume 19. Arthroscopy: Knee Surgery, Sports Traumatology; 2011. pp. 1411\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYounger J, McCue R, Mackey S. Pain outcomes: a brief review of instruments and techniques[J]. Curr Pain Headache Rep. 2009;13:39\u0026ndash;43.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang H, Tang K, Song X, et al. Effects of contralateral versus ipsilateral electroacupuncture for analgesia and rehabilitation after unilateral total knee arthroplasty: a randomized controlled trial[J]. Acupunct Med. 2024;42(4):183\u0026ndash;93.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Knee joint, Saphenous nerve, Protection Technology, Total Knee Arthroplasty, Modified surgery","lastPublishedDoi":"10.21203/rs.3.rs-6057173/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6057173/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eCompared with the traditional surgical method, this study aims to explore a saphenous nerve infrapatellar branch protection technique to address the issue of numbness and pain in the anterolateral skin of the knee joint after total knee arthroplasty, thereby improving patient satisfaction. In this study, we compared the effects of the modified TKA surgical incision and the traditional median surgical incision on anterolateral skin numbness and pain, as well as the protective techniques targeting the infrapatellar branch of the saphenous nerve. The goal was to reduce sensory disorders in the anterolateral skin of the knee, alleviate pain in the operative area, and ultimately improve patient satisfaction after surgery.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eIn this study, 60 patients who underwent TKA for the first time at Zhejiang Provincial Hospital of Traditional Chinese Medicine between January 2022 and June 2023 were selected and randomly divided into two groups: Modified group (M group n\u0026thinsp;=\u0026thinsp;31) and Traditional group (T group n\u0026thinsp;=\u0026thinsp;29). In M group, a modified approach was used to incise and visualize the articular cavity. The skin incision was the same length as that in the classic median knee surgery, and the visualization of the articular cavity was performed in two steps. First, an incision was made above the knee joint line, similar to the classic medial parapatellar approach, but the proximal end was extended proximally along the medial femoral tendon to relax the knee-extension device. In the second step, the proximal incision was retracted to both sides, and the skin below the joint line was incised longitudinally to protect all subcutaneous soft tissues in the superficial layer of the patellar tendon, which contained branches of the infrapatellar branch of the saphenous nerve, while maintaining skin tension. In T group, the articular cavity was exposed through the traditional medial parapatellar approach. All 60 patients underwent TKA performed by the same attending surgeon, and the same brand of knee prosthesis was uesd for all patients (no patellar surface replacement, only patellofemoral plasty). The skin sensation around the incision was statistically observed preoperatively, and at 2 weeks, 1 month, 3 months, 6 months, and 1 year postoperatively. This included the size of the distribution area of skin numbness and changes in numbness. The two groups were compared and analyzed to determine differences in anterior-lateral knee skin numbness and pain between the two surgical techniques. Data were collated through statistical analysis to compare the differences in numbness and pain between the two groups. This study aimed to explore whether the improved surgical technique was more effective in reducing the occurrence of numbness and pain in the postoperative period and to draw a conclusion.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThere was no statistically significant difference in the baseline characteristics between the two groups (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The P-value of the HSS scores of the two groups was greater than 0.05 in the preoperative, at 7 days postoperatively, at 2 weeks postoperatively, and at 1 month postoperatively, indicating no statistically significant difference. The P-value of the VAS scores of the two groups were greater than 0.05 preoperatively and at 1 day postoperatively, indicating no statistically significant difference. However, the P-value of the VAS scores were less than 0.001 at 3 days postoperatively, 7 days postoperatively, and 2 weeks postoperatively, indicating a statistically significant difference. The P-values for the numbness area of the two groups were less than 0.001 at 2 weeks postoperatively, 1 month postoperatively, 3 months postoperatively, 6 months postoperatively, and 1 year postoperatively, indicating a statistically significant difference. The area of numbness was smaller in the group with the modified surgical technique compared to the traditional surgery at the same time points. Additionally, numbness on the outer side of the incision in some of the patients treated with the modified technique was completely recovered.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThe modified incision-exposure technique used in this study effectively protects the infrapatellar branch of the saphenous nerve without causing operational difficulties in osteotomy, ligament balancing, gap balancing, or prosthesis implantation during total knee replacements. This technique results in a smaller area of postoperative skin numbness compared to the traditional surgical method, with less postoperative pain and faster recovery.\u003c/p\u003e","manuscriptTitle":"Application of saphenous nerve infrapatellar branch protection technique in total knee arthroplasty","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-03-27 05:09:41","doi":"10.21203/rs.3.rs-6057173/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-05-12T04:27:50+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-08T01:03:26+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-05T13:21:06+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"16322104943411616169385353374072375316","date":"2025-04-29T23:35:31+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-17T01:57:57+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-15T07:17:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"230640730832959734453178463957446440971","date":"2025-04-05T08:00:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"127459743156868872820227417993070391850","date":"2025-04-04T10:07:53+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"193712645232572734514149304732745740841","date":"2025-04-04T08:10:46+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-03-25T10:39:40+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-24T12:33:58+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Musculoskeletal Disorders","date":"2025-03-24T12:32:48+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"4cda9635-2876-4fd4-904b-bddda7678e4c","owner":[],"postedDate":"March 27th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-10-20T16:01:51+00:00","versionOfRecord":{"articleIdentity":"rs-6057173","link":"https://doi.org/10.1186/s12891-025-09099-5","journal":{"identity":"bmc-musculoskeletal-disorders","isVorOnly":false,"title":"BMC Musculoskeletal Disorders"},"publishedOn":"2025-10-14 15:57:39","publishedOnDateReadable":"October 14th, 2025"},"versionCreatedAt":"2025-03-27 05:09:41","video":"","vorDoi":"10.1186/s12891-025-09099-5","vorDoiUrl":"https://doi.org/10.1186/s12891-025-09099-5","workflowStages":[]},"version":"v1","identity":"rs-6057173","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6057173","identity":"rs-6057173","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}