To Study The Effect of Component alignment on outcome of total knee arthroplasty

To Study The Effect of Component alignment on outcome of 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 To Study The Effect of Component alignment on outcome of total knee arthroplasty sachin katna This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6465077/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract OBJECTIVE The present study used radiological parameters in the coronal, sagittal, and axial planes to investigate the influence of component alignment in total knee arthroplasty (TKA) on early postoperative functional outcomes. Materials and Methods The analysis of 26 cases over a 4-month follow-up revealed significant associations between component alignment and functional outcomes. Pre-operatively hip, knee ankle (HKA) angle is measured on the weight-bearing full-length lower limb radiograph. Secondly angle between the mechanical and anatomical axes of the femur is measured. Thirdly, the knee society score is calculated to assess the functional status of the knee pre-operatively. An X-ray knee joint was done postoperatively on post op day 0. A computed tomography (CT) scan of the lower limb from the hip to the ankle joint was done within 2-3 days of surgery to check for post-operative component alignment. The components in discussion are femoral and tibial, and their alignment is checked in 3 planes, that is, coronal, axial, and sagittal. Lastly, the knee society score is again calculated postoperatively to assess the outcome of the surgery RESULT A clear improvement in functional outcomes postoperatively was evident. The functional Knee Society Score (KSS) increased significantly (P value < 0.001) from a preoperative mean of 84.2 ± 4.0 to 93.8 ± 4.4. Similar improvements were seen in objective and satisfaction scores, indicating both clinical and patient-perceived success of the surgery. Notably, the expectation score remained relatively unchanged ( p value = 0.327 ), suggesting that the surgical outcomes met most patients’ preoperative expectations. In the coronal plane, both femoral (r = +0.424, p = 0.031). and tibial(r = +0.926, p < 0.001). Component alignments showed positive correlations with functional outcomes. The sagittal alignment of both femoral (r = +0.816, p < 0.001). and tibial (r = -0.947, p < 0.001). Components had a highly significant correlation with functional outcomes. Unlike the coronal and sagittal planes, axial plane alignment of both femoral and tibial components did not demonstrate a statistically significant correlation with postoperative functional scores CONCLUSION The take-home message from this study is clear: meticulous preoperative planning, precise intraoperative technique, and careful component placement are essential for optimizing patient outcomes. While individualized strategies may benefit select patients, particularly those with unique anatomical or functional demands, mechanical alignment continues to offer the most consistent and reproducible results, especially in the context of long-term implant survival. Orthopedics Orthopedic Surgery knee osteoarthritis arthroplasty functional outcome patient satisfaction Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 INTRODUCTION Osteoarthritis is the most common musculoskeletal disease, leading to functional decline and decreased quality of life. In 2020, approximately 528 million people, or 7.6% of the global population, were living with osteoarthritis [ 1 ]. Total Knee Replacement (TKR) is considered the gold standard surgical procedure for this condition, and its usage is rapidly increasing. TKR generally produces excellent functional outcomes; however, a significant proportion of patients remain dissatisfied after the procedure. This has led to a growing body of research focused on identifying predictors of poor outcomes and patient dissatisfaction following TKR [ 2 ] The primary goal of surgery is durable pain relief with the improvement of functional status. Proper alignment of the knee is considered to be one of the most influential factors in determining the long-term outcome after TKR. In TKR, there are two separate concepts of alignment: that of the limb as a whole and that of the component individually The various ALIGNMENT [ 3 ] schemes used to implant TKR are: Mechanical alignment has been the most widely used concept. It aims to CUT the distal femur and proximal tibia bone perpendicular to the mechanical axis in the coronal plane. The principle of mechanical alignment is to achieve a balanced load distribution between the medial and lateral compartments, to reduce polyethylene wear, and maximize the longevity of the implant [ 4 ]. Another preferred use is kinematic alignment’s whichs principle is to represent the natural pre arthritic alignment of the knee post-operatively. The mechanical axes of the femur and tibia are not considered. Native joint lines were reproduced using measured resected bones in the distal femur, posterior femur, and proximal tibia [ 5 ]. The functional outcome not only depends upon limb alignment but also on component positioning COMPONENT POSITIONING In total knee arthroplasty(TKA), it refers to the angular deviation between the prosthetic component and the patient’s axes. The alignment of each component has to be controlled in three planes, i.e, coronal, sagittal, and axial [ 6 ] FEMORAL COMPONENT Coronal plane alignment of the femoral component. In mechanical alignment, the distal femoral cuts are typically made at an angle of 2 to 7 degrees of valgus concerning the anatomical axis to achieve proper mechanical alignment. An alignment greater than 8 degrees or less than 2 degrees of valgus concerning the mechanical axis is a significant contributor to implant failure..The sagittal alignment of the femoral component is most commonly evaluated about the femoral anatomical axes. The primary goal in total knee replacement (TKR) is to position the femoral component in a neutral alignment, or with a flexion angle of 0 to 3 degrees relative to the femoral axis in the sagittal plane, using an intramedullary guide. Misalignment of the femoral component in the sagittal plane has been associated with reduced implant survival. For a correct alignment in rotation of the femoral component, there are several bone references such as the trans epicondylar axis, the Posterior condyle line, and the anteroposterior line. TIBIAL COMPONENT The objective of the tibial component in mechanical alignment is to maximize coverage to prevent settling and to ensure neutral alignment. This is accomplished by making the proximal tibial cut at a 90-degree angle to the mechanical axis. Malalignment of the tibial component alters the distribution of loading on the tibia, which increases the shear force at the tibiofemoral interface, ultimately leading to greater wear and tear. Sagittal plane alignment of the tibial component. The alignment of the tibial component in the sagittal plane has a drastic effect on the life of the implant, as alteration from normal alignment leads to a poor survival rate.To improve the survival rate and functional outcome following TKR posterior tibial slope should be kept as close to normal.The normal relationship between the orientation of the tibial tubercle and the tibial articular surface is used to determine whether the tibial component is in internal or external rotation. MATERIAL AND METHOD It's a prospective study. The study included diseased osteoarthritic knees undergoing either unilateral or bilateral primary Total knee arthroplasty from 1st August 2023 to 28th feb 2025.. Patients were followed up for 4 months. ( i.e, on post op day 14, 1 month, 2 months, 4 months ). All Surgeries were performed under spinal anaesthesia. A standard anterior midline approach with medial parapatellar reticular incision in a flexed knee was used in all the cases. The Cruciate retaining Triathlon total knee system by Stryker was used in all procedures. We aim for MECHANICAL ALIGNMENT in all cases.Pre-operatively hip, knee ankle (HKA) angle is measured on the weight-bearing full-length lower limb radiograph. It is used to assess knee alignment based on the mechanical axis of the femur and tibia. It is measured by one axis, which is drawn from the center of the femoral head to the center of the femoral notch, and a second axis, which is drawn from the tibial spine to the center of the ankle joint. The angle made between these two axes is the hip, knee ankle angle.as shown in figure 1 [7] Secondly, the knee society score is calculated to assess the functional status of the knee pre-operatively [8].An X-ray knee joint was done postoperatively on post op day 0 . A CT scan of the lower limb from hip to ankle joint was done within 2-3 days of surgery to check for post-operative component alignment. FEMORAL COMPOMENT ALIGNMENT To measure the placement of the femoral component in the coronal plane relative to the femoral axis postoperatively, a long-leg scannogram or CT scan topograph was performed. The femoral component's placement is assessed using the mechanical lateral distal femur angle (mLDFA), figure 2 which is the angle between the femoral mechanical axis and the condylar tangent line of the femoral components shown in figure 1. An angle of 90 degrees indicates neutral placement; an angle greater than 90 degrees indicates varus placement, while an angle less than 90 degrees indicates valgus placement of the femoral component. Both varus and valgus alignments can significantly impact implant survival. The sagittal alignment of the femoral components is typically assessed concerning the femoral anatomical axes. To measure the femoral component in the sagittal plane, a lateral view X-ray or sagittal orientation on a CT scan is required. This measurement involves determining the femoral flexion-extension angle (FEA) figure 3, which is the angle between the femoral anatomical axis and the distal cutting line of the femur, as in Figure 2 [7]. An FEA of 90 degrees indicates neutral placement. An FEA greater than 90 degrees indicates that the femoral component is in extension, while an FEA less than 90 degrees indicates that the femoral component is in flexion. To calculate the rotation of the femoral component, we need to obtain an axial cut from the CT scan. On this axial cut, we create an angle between the trans-epiconylar line and the prosthetic posterior condylar line, which is drawn by connecting the posterior flanges of the implant. The angle formed between these lines indicates the rotation of the femoral component. TIBIAL COMPONENT ALIGNMENT The measurement of tibial component placement in the coronal plane is based on its axes. For this measurement, a long-leg scanogram or a CT scan was performed. The placement of the tibial component is evaluated using the medial proximal tibial angle (mPTA) figure 4, which is the angle formed between a line drawn across the base of the tibial plate and the mechanical axis of the tibia.as in Figure 1 . An mPTA of 90 degrees indicates a neutral placement of the component. An mPTA greater than 90 degrees indicates valgus placement, while an mPTA less than 90 degrees indicates varus placement of the tibial component. The sagittal alignment of tibial components is typically assessed concerning the anatomical axes of the tibia. To measure the tibial component in the sagittal plane, a lateral view X-ray or a sagittal orientation from a CT scan is necessary. This measurement is done by assessing the tibial posterior slope angle (TSA) figure 5, which is defined as the angle between a line drawn across the bottom of the tibial plate and the axis of the tibial shaft as in figure 2. A TSA of 90 degrees indicates neutral placement, a TSA greater than 90 degrees signifies an anterior tibial slope, while a TSA less than 90 degrees indicates a posterior tibial slope. To measure the tibial component in the axial plane figure 6, an axial section from a CT scan is required. In this axial section, we analyze three cross sections of the tibia to determine the rotational position of the component relative to the tibial tubercle. Firstly,(a) the cut is made immediately distal to the component, is used to establish the geometric center of the proximal tibia. An oval is drawn to fit the proximal tibia, which is sized and rotated accordingly. The center of this oval represents the geometric center of the proximal tibia. The second cut (c) passes through the tibial component and defines the Tibial Component Angle (TCA). The TCA is measured as the perpendicular line to the transverse axis that intersects the posterior margins of the component. Lastly the most distal cut is taken through the tibial tubercle. Data from the previous two images are superimposed onto this cut. A line is drawn from the apex of the tubercle to the geometric center established earlier; this line is referred to as the tibial tubercle orientation.(b) The angle formed between this line and the TCA indicates the rotational position of the tibial component. Lastly, the knee society score is again calculated postoperatively to assess the outcome of the surgery [9] RESULTS The outcome of the cases based on radiological and functional parameters was assessed and is presented here. RADIOLOGICAL ANALYSIS (table 1 and 2 ) 1) In the Coronal plane:- Femoral component alignment, which was calculated by calculating mLDFA, varies from 85 to 90 degrees, with a Standard deviation of 1.701, a mean of 87.42, with a correlation coefficient of +0.424, and P value of 0.031 .Out of 26 cases, 15 cases exhibited a valgus alignment of 3 degrees or less (i.e., mLDFA range from 88 to 90 degrees). Among these 15, 10 cases achieved excellent functional outcomes (>95), while 5 showed good ones. The other 11 cases out of the total had a valgus alignment between 3 to 6 degrees (i.e., mLDFA range from 85 to 87 degrees) of the femoral component. Out of these 11, 6 cases resulted in good functional outcomes(90-95), and 5 cases had fair functional outcomes(<90). Tibial component alignment , which was calculated by calculating mPTA, varies from 85 to 90 degrees with a standard deviation of 2.17, with a mean of 87.38, with a correlation coefficient of + 0.926, with P value of < 0.001. Out of the 26 cases examined, 12 cases had less than 3 degrees of varus in the tibial component. Among these 12, 9 cases were aligned neutrally, meaning they had 0 degrees of varus or valgus. In terms of functional outcomes, 10 of these cases out of 12 achieved an excellent functional outcome, while 2 cases showed a good functional outcome. The other 14 cases out of the total had a varus alignment ranging from 3 to 6 degrees. Among these, 9 cases demonstrated a good functional outcome, and 5 cases showed a fair functional outcome. 2) In Sagittal plane :- The degree of femoral components ' flexion and extension was calculated in the sagittal plane by calculating the FEA, which varies from 87 to 90 degrees in our study, meaning the component was in 0 to 3 degrees of flexion with a mean of 87.5 and a standard deviation of 2.174. The correlation coefficient between femoral sagittal and functional outcome was +0.424 with p p-value of 0.031. Seventeen cases exhibited malalignment of less than 3 degrees, meaning the component was positioned in 0 to 3 degrees of flexion. Among these 17 cases, 10 achieved excellent functional outcomes (greater than 95), while the remaining 7 had good outcomes (ranging from 90 to 95). Additionally, 9 cases out of the total showed malalignment between 3 to 6 degrees, with the component positioned in 4 to 5 degrees of flexion. In this group, 4 cases achieved good functional outcomes, while 5 cases had fair outcomes (less than 90). The degree of posterior slope of tibial components was assessed in the sagittal plane, ranging from 83 to 90 degrees. A slope of 90 degrees indicates zero posterior slope, while 83 degrees corresponds to a posterior tibial slope of 7 degrees. The mean posterior slope was found to be 86 degrees, with a standard deviation of 2.280. The correlation coefficient was -0.947, with a significant p-value of less than 0.001. In the study, 10 cases had less than 3 degrees of malalignment (i.e., slopes ranging from 5 to 7 degrees), and among these, 6 cases exhibited a neutral tibial slope of 83 degrees. All cases in this group showed excellent functional outcomes (i.e., scores greater than 95) . Thirteen cases fell into the category of 3 to 6 degrees of malalignment, with slopes ranging from 2 to 4 degrees (86 to 88 degrees). Out of these 13, 11 patients achieved good functional outcomes (scores between 90 and 95), while 2 had fair outcomes (below 90). Finally, 3 cases were noted with malalignment greater than 6 degrees, with slopes ranging from 0 to 1 degree (89 and 90 degrees). All these cases had fair functional outcomes. 3) In Axial plane:- The rotation of the components was assessed in the axial plane. The femoral component rotation, calculated from CT scans, varied from 3 to 3.9 degrees of internal rotation, with a mean value of 3.43 degrees and a standard deviation of 0.27 degrees. Although these values are clinically significant, they did not exhibit a statistically significant impact, as indicated by a correlation coefficient of +0.173 and a p-value of 0.397. The tibial component rotation was also evaluated using CT scans, which revealed a range of 16 to 20 degrees of internal rotation concerning the tibial tuberosity. The mean value was 17.92 degrees with a standard deviation of 1.38 degrees, along with a correlation coefficient of +0.090 and a p-value of 0.663. No significant relationship was observed between the axial plane rotations (femoral and tibial) and the functional outcome scores. Table 1: overall femoral component relation to functional score FEMORAL COMPONENT fuctional score 6 degrees N(%) N(%) N(%) Excellent( 96-100) 10(90.9) 0 0 Good (91 -95) 1(9.1) 8(53.3) 0 Fair(<90) 0 7(46.7) 0 Total 11 15 0 P value <0.001 (significant ) Table 2: overall tibial component relation with functional score TIBIAL COMPONENT functional score 6 degrees N(%) N(%) N(%) Excellent( 96-100) 10(100) 0 0 Good (91 -95) 0 9 0 Fair(<90) 0 2 5(100) Total 10 11 5 P value <0.001 (significant ) FUNCTIONAL ANALYSIS (table 3) Functional outcome was calculated by using the Knee Society scoring system. Along with the functional outcome Knee Society also provides 3 different scores that are objective, satisfactory, and expectation. The pre-operative Knee Society Score was calculated, and by assessing the post-operative Knee Society Score, we were able to compare the two to evaluate the outcomes of Total Knee Arthroplasty (TKA). The objective Knee Society Score changed from 48.2 ± 4.5 pre-operatively to 72.3 ± 1.4 post-operatively, illustrating the improvement following surgery. The satisfaction score increased from 18.1 ± 3 pre-operatively to 35.6 ± 1.9 post-operatively, reflecting the enhancement in patient satisfaction levels. Interestingly, patient expectations regarding the surgery did not change significantly, with scores shifting from 13.7 ± 0.7 pre-operatively to 13.4 ± 1.1 post-operatively. Notably, the functional outcome showed a significant increase after surgery, rising from a pre-operative value of 84.2 ± 4.0 to a post-operative value of 93.8 ± 4.4, highlighting the benefits of TKA. DISCUSSION The present study aimed to investigate the influence of component alignment in total knee arthroplasty (TKA) on early postoperative functional outcomes using radiological parameters in the coronal, sagittal, and axial planes. The analysis of 26 cases over a 4-month follow-up revealed significant associations between component alignment and functional outcomes, with particularly strong correlations noted in tibial alignment. The following discussion explores the possible causes behind these findings and compares them with existing literature. A clear improvement in functional outcomes postoperatively was evident. The functional Knee Society Score (KSS) increased significantly (P value < 0.001) from a preoperative mean of 84.2 ± 4.0 to 93.8 ± 4.4. Similar improvements were seen in objective and satisfaction scores, indicating both clinical and patient-perceived success of the surgery. Notably, the expectation score remained relatively unchanged ( p value = 0.327 ), suggesting that the surgical outcomes met most patients’ preoperative expectations. Impact of Coronal Alignment [10] In the coronal plane, both femoral and tibial component alignments showed positive correlations with functional outcomes.The femoral component alignment, measured by mLDFA, had a moderate positive correlation (r = +0.424, p = 0.031). Patients with femoral alignment within 3° of neutral (88°-90°) had more favorable outcomes compared to those with more deviation. Femoral components aligned within 3° of the mechanical axis likely provided better joint biomechanics, balanced medial-lateral load distribution, and reduced stress on surrounding soft tissues. Mal alignment beyond 3° may increase lateral joint loading, leading to discomfort or instability, which translates into fairer functional outcomes. This supports the current surgical goal of aiming for a slightly valgus femoral component placement. [11] The tibial component alignment, measured by mPTA, exhibited a strong positive correlation with functional scores (r = +0.926, p < 0.001). Patients with less than 3° of varus in the tibial component had superior functional outcomes, especially those with near-neutral alignment. Proper coronal tibial alignment ensures uniform load transfer across the tibial plateau, improving joint mechanics. Mal alignment, particularly in varus, can lead to overloading of the medial compartment, early polyethylene wear, and knee pain-all of which reduce functional performance. This underscores the importance of achieving optimal coronal plane alignment to enhance postoperative function and stability.[12] Influence of Sagittal Alignment The sagittal alignment of both femoral and tibial components had a highly significant correlation with functional outcomes. Femoral sagittal alignment, measured by the flexion-extension angle (FEA), showed a strong positive correlation (r = +0.816, p < 0.001). Flexion angles between 0°-3° were associated with better outcomes, whereas increased flexion beyond 3° tended to correlate with decreased scores.[13] .A femoral component placed in slight flexion (0-3°) aligns more naturally with the femoral shaft, optimizing the patello-femoral mechanics and flexion arc. Excessive flexion may impair full extension or induce anterior notching, affecting gait and leading to anterior knee pain or instability. This aligns with biomechanical studies indicating that excessive femoral flexion can lead to abnormal joint kinematics and anterior knee pain.[14] Similarly, the posterior slope of the tibial component revealed a strong inverse relationship with functional outcome (r = -0.947, p < 0.001). A slope between 5°-7° (83°-85° on imaging) was associated with excellent outcomes. Decreased posterior slope (<2°) resulted in significantly poorer outcomes. Posterior slope aids in femoral rollback and flexion of the knee. A slope of 5°-7° (i.e., 83°-85° on radiograph) improves range of motion and reduces strain on the posterior cruciate ligament (if retained). Conversely, minimal or no slope (0°-2°) restricts rollback, resulting in functional limitations and increased joint stiffness, which directly impacts the KSS.[15]. These findings emphasize the importance of maintaining appropriate posterior tibial slope to allow for improved flexion mechanics and reduced stress on the prosthesis. Axial Plane Alignment and Functional Outcome Unlike the coronal and sagittal planes, axial plane alignment of both femoral and tibial components did not demonstrate a statistically significant correlation with postoperative functional scores. Femoral rotation had a correlation coefficient of +0.173 (p = 0.397), while tibial rotation had a negligible correlation of +0.090 (p = 0.663). This could be attributed to the relatively narrow range of rotational alignment in our sample or the short follow-up period of four months [16]. Despite using CT, interobserver variability or subtle anatomical differences may affect the accuracy of rotational measurements. also[17] Mild malrotation might be compensated by surrounding ligaments and muscles in the short term, masking their impact on early function. `[18]. Subtle rotational malalignments may manifest clinically over a longer duration Limitations of the Study : Like all clinical research, our study has its limitations. The sample size was relatively small, which may restrict the generalizability of our conclusions. Additionally, alignment was assessed using plain radiographs and 3D imaging, which, while standard, may introduce some observer variability and measurement bias. The short follow-up duration (4 months) may also not fully capture long-term trends, such as prosthetic wear or delayed complications. Moreover, the reliance on the Knee Society Score as the sole outcome measure may not encompass the full range of patient experiences, especially in terms of subjective satisfaction and quality of life. Future research with larger sample sizes, longer follow-up periods, and the incorporation of advanced tools such as gait analysis, pressure mapping, and patient-reported outcome measures (PROMs) would provide a more comprehensive understanding of the relationship between component alignment and functional success For practicing orthopedic surgeons, the take-home message from this study is clear: meticulous preoperative planning, precise intraoperative technique, and careful component placement are essential for optimizing patient outcomes. While individualized strategies may benefit select patients, particularly those with unique anatomical or functional demands, mechanical alignment continues to offer the most consistent and reproducible results, especially in the context of long-term implant survival. Multifactorial Nature of Outcomes: It is equally important to recognize that the success of TKA is multifactorial. While alignment is undeniably a cornerstone, other patient-related factors-including body mass index (BMI), muscle strength, ligament integrity, preoperative deformity, and rehabilitation adherence-play significant roles in determining overall outcomes. Notably, some patients with perfectly aligned components still report dissatisfaction, suggesting that subjective perceptions, pain tolerance, and expectations must also be considered. Addressing these psychological and social factors may help improve patient satisfaction and functional outcomes beyond what objective measurements can predict. Declarations The study was conducted after the ethical clearance from the committee of Sri Guru Ram Das Institute of Medical Science and Research, Sri Amritsar. conflict of interest On behalf of all authors, the corresponding author states that there is no conflict of interest References https://www.who.int/news-room/fact-sheets/detail/osteoarthritis#:~:text=In%202019%2C%20about%20528%20million,to%20co.... The effect of alignment and BMI on failure of total knee replacement. https://journals.lww.com/jbjsjournal/abstract/2011/09070/the_effect_of_alignment_and_bmi_on_failure_of.4.aspx. Coronal alignment in total knee arthroplasty: just how important is it?. https://www.sciencedirect.com/science/article/abs/pii/S0883540309001648. DOI::10.1016/j.arth.2009.04.034 Coronal alignment after total knee replacement. https://boneandjoint.org.uk/article/10.1302/0301-620x.73b5.1894655. Gromov K, Korchi M, Thomsen MG, Husted H, Troelsen A: What is the optimal alignment of the tibial and femoral components in knee arthroplasty?. Acta Orthop. 2014, 85:480-7. 10.3109/17453674.2014.940573 10.3389/fsurg.2022.991476 https://www.kneesociety.org/assets/docs/2011-KS-Score-c-Pre-Op_ENG.pdf. https://www.kneesociety.org/assets/docs/2011-KS-Score-c-Post-Op_ENG.pdf. Impact of Coronal Alignment in Total Knee Arthroplasty and Functional Outcome: 10.4236/ojo.2018.81002 DOI::10.1302/0301-620X.73B5.1894655 Parratte S, Pagnano MW, Trousdale RT, Berry DJ: Effect of postoperative mechanical axis alignment on the fifteen-year survival of modern, cemented total knee replacements. J Bone Joint Surg Am. 2010, 92:2143-2149. 10.2106/JBJS.I.01398 Han HS, Kang SB, Yoon KS: High incidence of loosening of the femoral component in older patients with total knee replacements. Clin Orthop Relat Res. 2008, 466:1592-1598. 10.1302/0301-620X.89B11.19840 Kim YH, Kim JS, Choe JW: Alignment and orientation of total knee arthroplasty components. J Arthroplasty. 2009, 24:560-568. 10.1302/0301-620X.90B9.20793 Matsuda S, Miura H, Nagamine R, et al.: Posterior tibial slope in the normal and varus knee. Am J Knee Surg. 1999, 12:165-168. Incavo SJ, Coughlin KM, Beynnon BD: Rotational alignment of the femoral component in total knee arthroplasty. Clin Orthop Relat Res. 2003, 162:167. 10.1097/BLO.0b013e3180332d97 Berger RA, Crossett LS, Jacobs JJ, Rubash HE: Malrotation causing patellofemoral complications after total knee arthroplasty. Clin Orthop Relat Res. 1998, 144:153. 10.1097/00003086-199811000-00021 Dennis DA, Komistek RD, Kim RH: A randomized, prospective evaluation of tibial rotational alignment using anatomical and functional axes. J Arthroplasty. 2001, 16:937-943. 10.1186/1471-2474-11-57 Table 3 Table 3 is not available with this version. Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 1 posted 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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FEA\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6465077/v1/516914f54b779f240f66c6ab.png"},{"id":81176488,"identity":"887fd4e3-7e0f-4de6-92bd-7d85427cd0da","added_by":"auto","created_at":"2025-04-23 06:23:57","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":217734,"visible":true,"origin":"","legend":"\u003cp\u003eshowing mPTA\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6465077/v1/18cb0c8ab2d4619dd84a4d98.png"},{"id":81176522,"identity":"11dfdd42-bdf1-4b3e-be75-550be2750844","added_by":"auto","created_at":"2025-04-23 06:24:01","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":47659,"visible":true,"origin":"","legend":"\u003cp\u003eshowing TSA\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-6465077/v1/2389f4fc950ba5119c63c770.png"},{"id":81176492,"identity":"af5f2561-8186-4d90-86d5-107fabb016f3","added_by":"auto","created_at":"2025-04-23 06:23:59","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":261605,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 3: axial plane for tibial component rotation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003epart a ) shows the geometric center\u003c/p\u003e\n\u003cp\u003epart b) Rotation of the tibial component\u003c/p\u003e\n\u003cp\u003epart c ) tibial component angle\u003c/p\u003e","description":"","filename":"03.png","url":"https://assets-eu.researchsquare.com/files/rs-6465077/v1/b339aefabec61a9e741a02de.png"},{"id":81176960,"identity":"4f8966cd-f712-4f7c-8c38-0b8d9b9e6a45","added_by":"auto","created_at":"2025-04-23 06:32:07","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3345167,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6465077/v1/4abd0698-c70f-4adc-bb11-3db7df618668.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003eTo Study The Effect of Component alignment on outcome of total knee arthroplasty\u003c/p\u003e","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eOsteoarthritis is the most common musculoskeletal disease, leading to functional decline and decreased quality of life. In 2020, approximately 528\u0026nbsp;million people, or 7.6% of the global population, were living with osteoarthritis [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Total Knee Replacement (TKR) is considered the gold standard surgical procedure for this condition, and its usage is rapidly increasing. TKR generally produces excellent functional outcomes; however, a significant proportion of patients remain dissatisfied after the procedure. This has led to a growing body of research focused on identifying predictors of poor outcomes and patient dissatisfaction following TKR [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eThe primary goal of surgery is durable pain relief with the improvement of functional status. Proper alignment of the knee is considered to be one of the most influential factors in determining the long-term outcome after TKR. In TKR, there are two separate concepts of alignment: that of the limb as a whole and that of the component individually\u003c/p\u003e \u003cp\u003eThe various ALIGNMENT [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] schemes used to implant TKR are:\u003c/p\u003e \u003cp\u003eMechanical alignment has been the most widely used concept. It aims to CUT the distal femur and proximal tibia bone perpendicular to the mechanical axis in the coronal plane. The principle of mechanical alignment is to achieve a balanced load distribution between the medial and lateral compartments, to reduce polyethylene wear, and maximize the longevity of the implant [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Another preferred use is kinematic alignment\u0026rsquo;s whichs principle is to represent the natural pre arthritic alignment of the knee post-operatively. The mechanical axes of the femur and tibia are not considered. Native joint lines were reproduced using measured resected bones in the distal femur, posterior femur, and proximal tibia [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. The functional outcome not only depends upon limb alignment but also on component positioning\u003c/p\u003e\n\u003ch3\u003eCOMPONENT POSITIONING\u003c/h3\u003e\n\u003cp\u003eIn total knee arthroplasty(TKA), it refers to the angular deviation between the prosthetic component and the patient\u0026rsquo;s axes. The alignment of each component has to be controlled in three planes, i.e, coronal, sagittal, and axial [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eFEMORAL COMPONENT\u003c/h2\u003e \u003cp\u003eCoronal plane alignment of the femoral component. In mechanical alignment, the distal femoral cuts are typically made at an angle of 2 to 7 degrees of valgus concerning the anatomical axis to achieve proper mechanical alignment. An alignment greater than 8 degrees or less than 2 degrees of valgus concerning the mechanical axis is a significant contributor to implant failure..The sagittal alignment of the femoral component is most commonly evaluated about the femoral anatomical axes. The primary goal in total knee replacement (TKR) is to position the femoral component in a neutral alignment, or with a flexion angle of 0 to 3 degrees relative to the femoral axis in the sagittal plane, using an intramedullary guide. Misalignment of the femoral component in the sagittal plane has been associated with reduced implant survival. For a correct alignment in rotation of the femoral component, there are several bone references such as the trans epicondylar axis, the Posterior condyle line, and the anteroposterior line.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eTIBIAL COMPONENT\u003c/h3\u003e\n\u003cp\u003eThe objective of the tibial component in mechanical alignment is to maximize coverage to prevent settling and to ensure neutral alignment. This is accomplished by making the proximal tibial cut at a 90-degree angle to the mechanical axis. Malalignment of the tibial component alters the distribution of loading on the tibia, which increases the shear force at the tibiofemoral interface, ultimately leading to greater wear and tear. Sagittal plane alignment of the tibial component. The alignment of the tibial component in the sagittal plane has a drastic effect on the life of the implant, as alteration from normal alignment leads to a poor survival rate.To improve the survival rate and functional outcome following TKR posterior tibial slope should be kept as close to normal.The normal relationship between the orientation of the tibial tubercle and the tibial articular surface is used to determine whether the tibial component is in internal or external rotation.\u003c/p\u003e"},{"header":"MATERIAL AND METHOD","content":"\u003cp\u003eIt\u0026apos;s a prospective study. The study included diseased osteoarthritic knees undergoing either unilateral or bilateral primary Total knee arthroplasty from 1st August 2023 to 28th feb 2025.. Patients were followed up for 4 months. ( i.e, on post op day 14, 1 month, 2 months, 4 months ). All Surgeries were performed under spinal anaesthesia. A standard anterior midline approach with medial parapatellar reticular incision in a flexed knee was used in all the cases. The Cruciate retaining Triathlon total knee system by Stryker was used in all procedures. We aim for MECHANICAL ALIGNMENT in all cases.Pre-operatively hip, knee ankle (HKA) angle is measured on the weight-bearing full-length lower limb radiograph. It is used to assess knee alignment based on the mechanical axis of the femur and tibia. It is measured by one axis, which is drawn from the center of the femoral head to the center of the femoral notch, and a second axis, which is drawn from the tibial spine to the center of the ankle joint. The angle made between these two axes is the hip, knee ankle angle.as shown in figure 1 [7]\u003c/p\u003e\n\u003cp\u003eSecondly, the knee society score is calculated to assess the functional status of the knee pre-operatively [8].An X-ray knee joint was done postoperatively on post op day 0 . A CT scan of the lower limb from hip to ankle joint was done within 2-3 days of surgery to check for post-operative component alignment.\u003c/p\u003e\n\u003cp\u003eFEMORAL COMPOMENT ALIGNMENT\u003c/p\u003e\n\u003cp\u003eTo measure the placement of the femoral component in the coronal plane relative to the femoral axis postoperatively, a long-leg scannogram or CT scan topograph was performed. The femoral component\u0026apos;s placement is assessed using the mechanical lateral distal femur angle (mLDFA), figure 2 which is the angle between the femoral mechanical axis and the condylar tangent line of the femoral components shown in figure 1. An angle of 90 degrees indicates neutral placement; an angle greater than 90 degrees indicates varus placement, while an angle less than 90 degrees indicates valgus placement of the femoral component. Both varus and valgus alignments can significantly impact implant survival.\u003c/p\u003e\n\u003cp\u003eThe sagittal alignment of the femoral components is typically assessed concerning the femoral anatomical axes. To measure the femoral component in the sagittal plane, a lateral view X-ray or sagittal orientation on a CT scan is required. This measurement involves determining the femoral flexion-extension angle (FEA) figure 3, which is the angle between the femoral anatomical axis and the distal cutting line of the femur, as in Figure 2 [7]. An FEA of 90 degrees indicates neutral placement. An FEA greater than 90 degrees indicates that the femoral component is in extension, while an FEA less than 90 degrees indicates that the femoral component is in flexion.\u003c/p\u003e\n\u003cp\u003eTo calculate the rotation of the femoral component, we need to obtain an axial cut from the CT scan. On this axial cut, we create an angle between the trans-epiconylar line and the prosthetic posterior condylar line, which is drawn by connecting the posterior flanges of the implant. The angle formed between these lines indicates the rotation of the femoral component.\u003c/p\u003e\n\u003cp\u003eTIBIAL COMPONENT ALIGNMENT\u003c/p\u003e\n\u003cp\u003eThe measurement of tibial component placement in the coronal plane is based on its axes. For this measurement, a long-leg scanogram or a CT scan was performed. The placement of the tibial component is evaluated using the medial proximal tibial angle (mPTA) figure 4, which is the angle formed between a line drawn across the base of the tibial plate and the mechanical axis of the tibia.as in Figure 1 . An mPTA of 90 degrees indicates a neutral placement of the component. An mPTA greater than 90 degrees indicates valgus placement, while an mPTA less than 90 degrees indicates varus placement of the tibial component.\u003c/p\u003e\n\u003cp\u003eThe sagittal alignment of tibial components is typically assessed concerning the anatomical axes of the tibia. To measure the tibial component in the sagittal plane, a lateral view X-ray or a sagittal orientation from a CT scan is necessary. This measurement is done by assessing the tibial posterior slope angle (TSA) figure 5, which is defined as the angle between a line drawn across the bottom of the tibial plate and the axis of the tibial shaft as in figure 2. A TSA of 90 degrees indicates neutral placement, a TSA greater than 90 degrees signifies an anterior tibial slope, while a TSA less than 90 degrees indicates a posterior tibial slope.\u003c/p\u003e\n\u003cp\u003eTo measure the tibial component in the axial plane figure 6, an axial section from a CT scan is required. In this axial section, we analyze three cross sections of the tibia to determine the rotational position of the component relative to the tibial tubercle. Firstly,(a) the\u0026nbsp;cut is made immediately distal to the component, is used to establish the geometric center of the proximal tibia. An oval is drawn to fit the proximal tibia, which is sized and rotated accordingly. The center of this oval represents the geometric center of the proximal tibia. The second cut (c) passes through the tibial component and defines the Tibial Component Angle (TCA). The TCA is measured as the perpendicular line to the transverse axis that intersects the posterior margins of the component. Lastly the most distal cut is taken through the tibial tubercle. Data from the previous two images are superimposed onto this cut. A line is drawn from the apex of the tubercle to the geometric center established earlier; this line is referred to as the tibial tubercle orientation.(b)\u003c/p\u003e\n\u003cp\u003eThe angle formed between this line and the TCA indicates the rotational position of the tibial component.\u003c/p\u003e\n\u003cp\u003eLastly, the knee society score is again calculated postoperatively to assess the outcome of the surgery [9]\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003eThe outcome of the cases based on radiological and functional parameters was assessed and is presented here.\u003c/p\u003e\n\u003cp\u003eRADIOLOGICAL ANALYSIS (table 1 and 2 )\u003c/p\u003e\n\u003cp\u003e1)\u0026nbsp;In the Coronal plane:-\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eFemoral component\u003c/strong\u003e alignment, which was calculated by calculating mLDFA, varies from 85 to 90 degrees, with a Standard deviation of 1.701, a mean of 87.42, with a correlation coefficient of +0.424, and P value of 0.031 .Out of 26 cases, 15 cases exhibited a valgus alignment of 3 degrees or less (i.e., mLDFA range from 88 to 90 degrees). Among these 15, 10 cases achieved excellent functional outcomes (\u0026gt;95), while 5 showed good ones. The other 11 cases out of the total had a valgus alignment between 3 to 6 degrees (i.e., mLDFA range from 85 to 87 degrees) of the femoral component. Out of these 11, 6 cases resulted in good functional outcomes(90-95), and 5 cases had fair functional outcomes(\u0026lt;90).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTibial component\u003c/strong\u003e alignment , which was calculated by calculating mPTA, varies from 85 to 90 degrees with a standard deviation of 2.17, with a mean of 87.38, with a correlation coefficient of + 0.926, with P value of \u0026lt; 0.001. Out of the 26 cases examined, 12 cases had less than 3 degrees of varus in the tibial component. Among these 12, 9 cases were aligned neutrally, meaning they had 0 degrees of varus or valgus. In terms of functional outcomes, 10 of these cases out of 12 achieved an excellent functional outcome, while 2 cases showed a good functional outcome. The other 14 cases out of the total had a varus alignment ranging from 3 to 6 degrees. Among these, 9 cases demonstrated a good functional outcome, and 5 cases showed a fair functional outcome.\u003c/p\u003e\n\u003cp\u003e2)\u0026nbsp;In Sagittal plane :-\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;The degree of \u003cstrong\u003efemoral components\u003c/strong\u003e\u0026apos; flexion and extension was calculated in the sagittal plane by calculating the FEA, which varies from 87 to\u0026nbsp;90 degrees in our study, meaning the component was in 0 to 3 degrees of flexion with a mean of 87.5 and a standard deviation of 2.174. The correlation coefficient between femoral sagittal and functional outcome was +0.424 with p p-value of 0.031. Seventeen cases exhibited malalignment of less than 3 degrees, meaning the component was positioned in 0 to 3 degrees of flexion. Among these 17 cases, 10 achieved excellent functional outcomes (greater than 95), while the remaining 7 had good outcomes (ranging from 90 to 95). Additionally, 9 cases out of the total showed malalignment between 3 to 6 degrees, with the component positioned in 4 to 5 degrees of flexion. In this group, 4 cases achieved good functional outcomes, while 5 cases had fair outcomes (less than 90).\u003c/p\u003e\n\u003cp\u003eThe degree of \u003cstrong\u003eposterior slope of tibial components\u0026nbsp;\u003c/strong\u003ewas assessed in the sagittal plane, ranging from 83 to 90 degrees. A slope of 90 degrees indicates zero posterior slope, while 83 degrees corresponds to a posterior tibial slope of 7 degrees. The mean posterior slope was found to be 86 degrees, with a standard deviation of 2.280. The correlation coefficient was -0.947, with a significant p-value of less than 0.001. In the study, 10 cases had less than 3 degrees of malalignment (i.e., slopes ranging from 5 to 7 degrees), and among these, 6 cases exhibited a neutral tibial slope of 83 degrees. All cases in this group showed excellent functional outcomes (i.e., scores greater than 95) . Thirteen cases fell into the category of 3 to 6 degrees of malalignment, with slopes ranging from 2 to 4 degrees (86 to 88 degrees). Out of these 13, 11 patients achieved good functional outcomes (scores between 90 and 95), while 2 had fair outcomes (below 90). Finally, 3 cases were noted with malalignment greater than 6 degrees, with slopes ranging from 0 to 1 degree (89 and 90 degrees). All these cases had fair functional outcomes.\u003c/p\u003e\n\u003cp\u003e3)\u0026nbsp;In Axial plane:-\u003c/p\u003e\n\u003cp\u003eThe rotation of the components was assessed in the axial plane. The \u003cstrong\u003efemoral component\u003c/strong\u003e rotation, calculated from CT scans, varied from 3 to 3.9 degrees of internal rotation, with a mean value of 3.43 degrees and a standard deviation of 0.27 degrees. Although these values are clinically significant, they did not exhibit a statistically significant impact, as indicated by a correlation coefficient of +0.173 and a p-value of 0.397.\u003c/p\u003e\n\u003cp\u003eThe \u003cstrong\u003etibial component\u0026nbsp;\u003c/strong\u003erotation was also evaluated using CT scans, which revealed a range of 16 to 20 degrees of internal rotation concerning the tibial tuberosity. The mean value was 17.92 degrees with a standard deviation of 1.38 degrees, along with a correlation coefficient of +0.090 and a p-value of 0.663.\u003c/p\u003e\n\u003cp\u003eNo significant relationship was observed between the axial plane rotations (femoral and tibial) and the functional outcome scores.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eTable 1: overall femoral component relation to functional score\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"3\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"3\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;FEMORAL COMPONENT\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp;fuctional score\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026lt;3 degree malalignment\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp;3-6 degrees\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026gt;6 degrees\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eN(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eN(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eN(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eExcellent( 96-100)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e10(90.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eGood (91 -95)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1(9.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e8(53.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eFair(\u0026lt;90)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e7(46.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eP value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\"\u003e\n \u003cp\u003e\u0026lt;0.001 (significant )\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2: overall tibial component relation with functional score\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"3\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"3\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;TIBIAL COMPONENT\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp;functional score\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026lt;3 degree malalignment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp;3-6 degrees\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026gt;6 degrees\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eN(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eN(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eN(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eExcellent( 96-100)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e10(100)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eGood (91 -95)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eFair(\u0026lt;90)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e5(100)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eP value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\"\u003e\n \u003cp\u003e\u0026lt;0.001 (significant )\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eFUNCTIONAL ANALYSIS (table 3)\u003c/p\u003e\n\u003cp\u003eFunctional outcome was calculated by using the Knee Society scoring system. Along with the functional outcome Knee Society also provides 3 different scores that are objective, satisfactory, and expectation. The pre-operative Knee Society Score was calculated, and by assessing the post-operative Knee Society Score, we were able to compare the two to evaluate the outcomes of Total Knee Arthroplasty (TKA). The objective Knee Society Score changed from 48.2 \u0026plusmn; 4.5 pre-operatively to 72.3 \u0026plusmn; 1.4 post-operatively, illustrating the improvement following surgery. The satisfaction score increased from 18.1 \u0026plusmn; 3 pre-operatively to 35.6 \u0026plusmn; 1.9 post-operatively, reflecting the enhancement in patient satisfaction levels. Interestingly, patient expectations regarding the surgery did not change significantly, with scores shifting from 13.7 \u0026plusmn; 0.7 pre-operatively to 13.4 \u0026plusmn; 1.1 post-operatively. Notably, the functional outcome showed a significant increase after surgery, rising from a pre-operative value of 84.2 \u0026plusmn; 4.0 to a post-operative value of 93.8 \u0026plusmn; 4.4, highlighting the benefits of TKA.\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThe present study aimed to investigate the influence of component alignment in total knee arthroplasty (TKA) on early postoperative functional outcomes using radiological parameters in the coronal, sagittal, and axial planes. The analysis of 26 cases over a 4-month follow-up revealed significant associations between component alignment and functional outcomes, with particularly strong correlations noted in tibial alignment. The following discussion explores the possible causes behind these findings and compares them with existing literature.\u003c/p\u003e\n\u003cp\u003eA clear improvement in functional outcomes postoperatively was evident. The functional Knee Society Score (KSS) increased significantly (P value \u0026lt; 0.001) from a preoperative mean of 84.2 \u0026plusmn; 4.0 to 93.8 \u0026plusmn; 4.4. Similar improvements were seen in objective and satisfaction scores, indicating both clinical and patient-perceived success of the surgery. Notably, the expectation score remained relatively unchanged ( p value = 0.327 ), suggesting that the surgical outcomes met most patients\u0026rsquo; preoperative expectations.\u003c/p\u003e\n\u003cp\u003eImpact of Coronal Alignment [10]\u003c/p\u003e\n\u003cp\u003eIn the coronal plane, both femoral and tibial component alignments showed positive correlations with functional outcomes.The femoral component alignment, measured by mLDFA, had a moderate positive correlation (r = +0.424, p = 0.031). Patients with femoral alignment within 3\u0026deg; of neutral (88\u0026deg;-90\u0026deg;) had more favorable outcomes compared to those with more deviation. Femoral components aligned within 3\u0026deg; of the mechanical axis likely provided better joint biomechanics, balanced medial-lateral load distribution, and reduced stress on surrounding soft tissues. Mal alignment beyond 3\u0026deg; may increase lateral joint loading, leading to discomfort or instability, which translates into fairer functional outcomes. This supports the current surgical goal of aiming for a slightly valgus femoral component placement. [11]\u003c/p\u003e\n\u003cp\u003eThe tibial component alignment, measured by mPTA, exhibited a strong positive correlation with functional scores (r = +0.926, p \u0026lt; 0.001). Patients with less than 3\u0026deg; of varus in the tibial component had superior functional outcomes, especially those with near-neutral alignment. Proper coronal tibial alignment ensures uniform load transfer across the tibial plateau, improving joint mechanics.\u0026nbsp;Mal alignment, particularly in varus, can lead to overloading of the medial compartment, early polyethylene wear, and knee pain-all of which reduce functional performance.\u0026nbsp;This underscores the importance of achieving optimal coronal plane alignment to enhance postoperative function and stability.[12]\u003c/p\u003e\n\u003cp\u003eInfluence of Sagittal Alignment\u003c/p\u003e\n\u003cp\u003eThe sagittal alignment of both femoral and tibial components had a highly significant correlation with functional outcomes. Femoral sagittal alignment, measured by the flexion-extension angle (FEA), showed a strong positive correlation (r = +0.816, p \u0026lt; 0.001). Flexion angles between 0\u0026deg;-3\u0026deg; were associated with better outcomes, whereas increased flexion beyond 3\u0026deg; tended to correlate with decreased scores.[13] .A femoral component placed in slight flexion (0-3\u0026deg;) aligns more naturally with the femoral shaft, optimizing the patello-femoral mechanics and flexion arc. Excessive flexion may impair full extension or induce anterior notching, affecting gait and leading to anterior knee pain or instability. This aligns with biomechanical studies indicating that excessive femoral flexion can lead to abnormal joint kinematics and anterior knee pain.[14]\u003c/p\u003e\n\u003cp\u003eSimilarly, the posterior slope of the tibial component revealed a strong inverse relationship with functional outcome (r = -0.947, p \u0026lt; 0.001). A slope between 5\u0026deg;-7\u0026deg; (83\u0026deg;-85\u0026deg; on imaging) was associated with excellent outcomes. Decreased posterior slope (\u0026lt;2\u0026deg;) resulted in significantly poorer outcomes. Posterior slope aids in femoral rollback and flexion of the knee. A slope of 5\u0026deg;-7\u0026deg; (i.e., 83\u0026deg;-85\u0026deg; on radiograph) improves range of motion and reduces strain on the posterior cruciate ligament (if retained). Conversely, minimal or no slope (0\u0026deg;-2\u0026deg;) restricts rollback, resulting in functional limitations and increased joint stiffness, which directly impacts the KSS.[15]. These findings emphasize the importance of maintaining appropriate posterior tibial slope to allow for improved flexion mechanics and reduced stress on the prosthesis.\u003c/p\u003e\n\u003cp\u003eAxial Plane Alignment and Functional Outcome\u003c/p\u003e\n\u003cp\u003eUnlike the coronal and sagittal planes, axial plane alignment of both femoral and tibial components did not demonstrate a statistically significant correlation with postoperative functional scores. Femoral rotation had a correlation coefficient of +0.173 (p = 0.397), while tibial rotation had a negligible correlation of +0.090 (p = 0.663). This could be attributed to the relatively narrow range of rotational alignment in our sample or the short follow-up period of four months [16]. Despite using CT, interobserver variability or subtle anatomical differences may affect the accuracy of rotational measurements. also[17] Mild malrotation might be compensated by surrounding ligaments and muscles in the short term, masking their impact on early function.\u003csup\u003e`[18].\u0026nbsp;\u003c/sup\u003eSubtle rotational malalignments may manifest clinically over a longer duration\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLimitations of the Study\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003eLike all clinical research, our study has its limitations. The sample size was relatively small, which may restrict the generalizability of our conclusions. Additionally, alignment was assessed using plain radiographs and 3D imaging, which, while standard, may introduce some observer variability and measurement bias. The short follow-up duration (4 months) may also not fully capture long-term trends, such as prosthetic wear or delayed complications. Moreover, the reliance on the Knee Society Score as the sole outcome measure may not encompass the full range of patient experiences, especially in terms of subjective satisfaction and quality of life. Future research with larger sample sizes, longer follow-up periods, and the incorporation of advanced tools such as gait analysis, pressure mapping, and patient-reported outcome measures (PROMs) would provide a more comprehensive understanding of the relationship between component alignment and functional success\u003c/p\u003e\n\u003cp\u003eFor practicing orthopedic surgeons, the take-home message from this study is clear: meticulous preoperative planning, precise intraoperative technique, and careful component placement are essential for optimizing patient outcomes. While individualized strategies may benefit select patients, particularly those with unique anatomical or functional demands, mechanical alignment continues to offer the most consistent and reproducible results, especially in the context of long-term implant survival.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMultifactorial Nature of Outcomes:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIt is equally important to recognize that the success of TKA is multifactorial. While alignment is undeniably a cornerstone, other patient-related factors-including body mass index (BMI), muscle strength, ligament integrity, preoperative deformity, and rehabilitation adherence-play significant roles in determining overall outcomes. Notably, some patients with perfectly aligned components still report dissatisfaction, suggesting that subjective perceptions, pain tolerance, and expectations must also be considered. Addressing these psychological and social factors may help improve patient satisfaction and functional outcomes beyond what objective measurements can predict.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eThe study was conducted after the ethical clearance from the committee of Sri Guru Ram Das Institute of Medical Science and Research, Sri Amritsar.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003econflict of interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOn behalf of all authors, the corresponding author states that there is no conflict of interest\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003ehttps://www.who.int/news-room/fact-sheets/detail/osteoarthritis#:~:text=In%202019%2C%20about%20528%20million,to%20co....\u003c/li\u003e\n \u003cli\u003eThe effect of alignment and BMI on failure of total knee replacement. https://journals.lww.com/jbjsjournal/abstract/2011/09070/the_effect_of_alignment_and_bmi_on_failure_of.4.aspx.\u003c/li\u003e\n \u003cli\u003eCoronal alignment in total knee arthroplasty: just how important is it?. https://www.sciencedirect.com/science/article/abs/pii/S0883540309001648.\u003c/li\u003e\n \u003cli\u003eDOI::10.1016/j.arth.2009.04.034\u003c/li\u003e\n \u003cli\u003eCoronal alignment after total knee replacement. https://boneandjoint.org.uk/article/10.1302/0301-620x.73b5.1894655.\u003c/li\u003e\n \u003cli\u003eGromov K, Korchi M, Thomsen MG, Husted H, Troelsen A: What is the optimal alignment of the tibial and femoral components in knee arthroplasty?. Acta Orthop. 2014, 85:480-7. 10.3109/17453674.2014.940573\u003c/li\u003e\n \u003cli\u003e10.3389/fsurg.2022.991476\u003c/li\u003e\n \u003cli\u003ehttps://www.kneesociety.org/assets/docs/2011-KS-Score-c-Pre-Op_ENG.pdf.\u003c/li\u003e\n \u003cli\u003ehttps://www.kneesociety.org/assets/docs/2011-KS-Score-c-Post-Op_ENG.pdf.\u003c/li\u003e\n \u003cli\u003eImpact of Coronal Alignment in Total Knee Arthroplasty and Functional Outcome: 10.4236/ojo.2018.81002\u003c/li\u003e\n \u003cli\u003eDOI::10.1302/0301-620X.73B5.1894655\u003c/li\u003e\n \u003cli\u003eParratte S, Pagnano MW, Trousdale RT, Berry DJ: Effect of postoperative mechanical axis alignment on the fifteen-year survival of modern, cemented total knee replacements. J Bone Joint Surg Am. 2010, 92:2143-2149. 10.2106/JBJS.I.01398\u003c/li\u003e\n \u003cli\u003eHan HS, Kang SB, Yoon KS: High incidence of loosening of the femoral component in older patients with total knee replacements. Clin Orthop Relat Res. 2008, 466:1592-1598. 10.1302/0301-620X.89B11.19840\u003c/li\u003e\n \u003cli\u003eKim YH, Kim JS, Choe JW: Alignment and orientation of total knee arthroplasty components. J Arthroplasty. 2009, 24:560-568. 10.1302/0301-620X.90B9.20793\u003c/li\u003e\n \u003cli\u003eMatsuda S, Miura H, Nagamine R, et al.: Posterior tibial slope in the normal and varus knee. Am J Knee Surg. 1999, 12:165-168.\u003c/li\u003e\n \u003cli\u003eIncavo SJ, Coughlin KM, Beynnon BD: Rotational alignment of the femoral component in total knee arthroplasty. Clin Orthop Relat Res. 2003, 162:167. 10.1097/BLO.0b013e3180332d97\u003c/li\u003e\n \u003cli\u003eBerger RA, Crossett LS, Jacobs JJ, Rubash HE: Malrotation causing patellofemoral complications after total knee arthroplasty. Clin Orthop Relat Res. 1998, 144:153. 10.1097/00003086-199811000-00021\u003c/li\u003e\n \u003cli\u003eDennis DA, Komistek RD, Kim RH: A randomized, prospective evaluation of tibial rotational alignment using anatomical and functional axes. J Arthroplasty. 2001, 16:937-943. 10.1186/1471-2474-11-57\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Table 3","content":"Table 3 is not available with this version. "}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"sri guru ram das institute of medical science and reseach amritsar","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"knee osteoarthritis, arthroplasty, functional outcome, patient satisfaction ","lastPublishedDoi":"10.21203/rs.3.rs-6465077/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6465077/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eOBJECTIVE\u003c/p\u003e\n\u003cp\u003eThe present study used radiological parameters in the coronal, sagittal, and axial planes to investigate the influence of component alignment in total knee arthroplasty (TKA) on early postoperative functional outcomes.\u003c/p\u003e\n\u003cp\u003eMaterials and Methods\u003c/p\u003e\n\u003cp\u003eThe analysis of 26 cases over a 4-month follow-up revealed significant associations between component alignment and functional outcomes.\u0026nbsp;Pre-operatively hip, knee ankle (HKA) angle is measured on the weight-bearing full-length lower limb radiograph. Secondly angle between the mechanical and anatomical axes of the femur is measured. Thirdly, the knee society score is calculated to assess the functional status of the knee pre-operatively. An X-ray knee joint was done postoperatively on post op day 0. A computed tomography (CT) scan of the lower limb from the hip to the ankle joint was done within 2-3 days of surgery to check for post-operative component alignment.\u0026nbsp;The components in discussion are femoral and tibial, and their alignment is checked in 3 planes, that is, coronal, axial, and sagittal.\u0026nbsp;Lastly, the knee society score is again calculated postoperatively to assess the outcome of the surgery\u003c/p\u003e\n\u003cp\u003eRESULT\u003c/p\u003e\n\u003cp\u003eA clear improvement in functional outcomes postoperatively was evident. The functional Knee Society Score (KSS) increased significantly (P value \u0026lt; 0.001) from a preoperative mean of 84.2 ± 4.0 to 93.8 ± 4.4. Similar improvements were seen in objective and satisfaction scores, indicating both clinical and patient-perceived success of the surgery. Notably, the expectation score remained relatively unchanged ( p value = 0.327 ), suggesting that the surgical outcomes met most patients’ preoperative expectations.\u0026nbsp;In the coronal plane, both femoral\u0026nbsp;(r = +0.424, p = 0.031). and tibial(r = +0.926, p \u0026lt; 0.001). Component alignments showed positive correlations with functional outcomes. The sagittal alignment of both femoral\u0026nbsp;(r = +0.816, p \u0026lt; 0.001). and tibial (r = -0.947, p \u0026lt; 0.001). Components had a highly significant correlation with functional outcomes. Unlike the coronal and sagittal planes, axial plane alignment of both femoral and tibial components did not demonstrate a statistically significant correlation with postoperative functional scores\u003c/p\u003e\n\u003cp\u003eCONCLUSION\u003c/p\u003e\n\u003cp\u003eThe take-home message from this study is clear: meticulous preoperative planning, precise intraoperative technique, and careful component placement are essential for optimizing patient outcomes. While individualized strategies may benefit select patients, particularly those with unique anatomical or functional demands, mechanical alignment continues to offer the most consistent and reproducible results, especially in the context of long-term implant survival.\u003c/p\u003e","manuscriptTitle":"To Study The Effect of Component alignment on outcome of total knee arthroplasty","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-23 06:23:13","doi":"10.21203/rs.3.rs-6465077/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"59b2f553-2d20-45bf-a3ff-02d0300d5b32","owner":[],"postedDate":"April 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":47267476,"name":"Orthopedics"},{"id":47267477,"name":"Orthopedic Surgery"}],"tags":[],"updatedAt":"2025-04-23T06:23:14+00:00","versionOfRecord":[],"versionCreatedAt":"2025-04-23 06:23:13","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6465077","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6465077","identity":"rs-6465077","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}