Extensor Mechanism Injuries after Primary Total Knee Arthroplasty

Extensor Mechanism Injuries after Primary 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 Extensor Mechanism Injuries after Primary Total Knee Arthroplasty Lawrence Jajou, Brian Golasa, Daniel McCall This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5404800/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 Background : Extensor mechanism injuries after total knee arthroplasty (TKA) continue to be a difficult complication to treat and can be associated with devastating outcomes. This study attempts to review the prevalence, treatment types, and outcomes of extensor mechanism injuries after total knee arthroplasty within a cohort of patients. Methods : Using a clinical research database, a retrospective cohort study was performed via chart review of patients who underwent a total knee arthroplasty over the course of 7 years from 7 hospitals within the same hospital system. The charts were then screened for subsequent operative repair of the ipsilateral extensor mechanism at a later date. Patient characteristics, implants, type of extensor mechanism injury, fixation type, subsequent surgeries were evaluated. Results : Of the 6064 total knee arthroplasties, 104 patients with 105 (1.73%) knees went on to have extensor mechanism injuries. Quadriceps tendon injuries were the most common, followed by patellar tendon, and then patella fractures. Median time to injury was 70 days. Patients requiring additional surgery beyond initial repair of extensor mechanism injury was 47.6% (50/105). Additionally, 33% (35/105) went on to have revision of component(s) and 17.1% (18-105) received treatment for prosthetic joint infection. Conclusions : While overall rare, extensor mechanism injuries after total knee arthroplasty can pose serious complications beyond initial repair, including need for additional surgery, infection, revision, and even amputation. Careful consideration should be taken by the treating surgeon when faced with these injuries to avoid further complications. Extensor Mechanism Quadriceps Patella Tendon Total Knee Arthroplasty Figures Figure 1 Background/Introduction Primary total knee arthroplasty (TKA) continues to become a more common surgery in the orthopedic community. With projections of primary TKA estimated to continually increase[1], it can be presumed that there will also be a rise in extensor mechanism injuries. Therefore, understanding the technique, outcomes, complications, and the way these are treated remains imperative. Specifically, extensor mechanism injuries can be a devastating complication to primary TKA and pose as a difficult complication to manage. While extensor mechanism injuries occur in about 0.17-2.5% of primary total knees, they pose difficulty in treatment and worse patient outcomes [2], [4]. Injury to the extensor mechanism includes damage to the quadriceps tendon, patella, patellar tendon, or retinaculum that aid in extension of the knee. History has shown that outcomes after conservatively treated extensor mechanism injuries in the setting of TKA are extremely poor, and therefore this is reserved for the low function, low demand, elderly population [3]. For the vast majority of these patients, surgical intervention is indicated. The presence of a TKA prosthesis can make surgical treatment of extensor mechanism injuries more difficult due to potential stiffness, scar tissue, decreased bone stock, and presence of a patellar component, which may limit treatment options. Additionally, studies have shown that these injuries routinely do poorly with lower functional outcomes and patient satisfaction scores when compared to uncomplicated TKA (3). Surgical treatment varies depending on the type and severity of the injury. Soft tissue structures can undergo repair versus reconstruction, with some literature favoring reconstruction with the use of cadaveric or synthetic grafts [4]. Patellar fractures can be treated with open reduction and internal fixation, revision of the patellar component, or patellectomy. Despite the various treatment options, there is no one treatment option for each extensor mechanism injury after TKA. With the rise of TKA procedures it is important to understand the various treatment options and their outcomes. This study aims to evaluate the rate and sequelae of extensor mechanism injuries after TKA in a cohort of patients. Materials And Methods Using the William Beaumont clinical research database (CRDB) (including all 7 of the system’s hospitals in Michigan), all patients who underwent primary TKA from January 1, 2015, to December 31, 2022, were obtained. These patients were then evaluated for subsequent operative encounters within the Beaumont Health system for extensor mechanism injuries to the ipsilateral leg as the TKA. Extensor mechanism injury included any injury to the quadriceps tendon, patellar tendon, patellar bone, patellar polyethylene, or retinaculum. Inclusion criteria were patients who underwent primary TKA within the above time period and age 18 or older at the time of index surgery. Exclusion criteria included patients having undergone TKA prior to the time period of study, patients below the age of 18 at the time of index surgery, revision total knee arthroplasty prior to extensor mechanism injury, and patients with known ipsilateral extensor mechanism injury prior to primary total knee arthroplasty. Once patients who had subsequent extensor mechanism injuries were isolated via the CRDB (Figure 1), chart review was then used to identify baseline patient characteristics, time to extensor mechanism injury, type of extensor mechanism injury, patellar implant specifications, and extensor mechanism surgical fixation type. Baseline patient characteristics recorded included gender, age, and BMI. Additionally, it was evaluated whether patients required further surgeries to the ipsilateral knee, treatment for infection, revision (of at least 1 component) of the TKA, or if patient went on to require fusion or amputation. Lastly, comparisons were secondarily made regarding extensor mechanism injury and patellar size, gender, age, BMI, and number of additional surgeries. Statistical Analysis : Univariate analyses were conducted to evaluate the association between patient characteristics and the outcomes of incidence of infection (Table 4) and injury knee (Table 5). Patient characteristics were stratified by outcome and compared using Mann-Whitney U tests for continuous variables and Pearson’s Chi-Squared tests for categorical variables. Spearman’s rank correlation coefficient ( ρ ) was computed to assess the correlation between number of extra surgeries and age, BMI and patella implant size respectively. The correlation coefficients indicated negligible to weak correlations and were not statistically significant (Age: ρ ) = -0.06, p = 0.543; BMI: ( ρ ) = 0.01, p = 0.937; Size: ( ρ) = 0.13, p = 0.208). Results 6064 primary TKA procedures were found from January 1, 2015 to December 31, 2022. Of these, 105 knees in 104 patients were found to have surgical intervention on the ipsilateral extensor mechanism (Figure 1). The average age was 67.7 years (43-85). There were 70 female knees and 35 male knees included in this study. The last patient characteristic reviewed was BMI, which averaged 34.99 (18.0-60.17). In regard to implants, the patella was resurfaced in 103/105 knees (98%). Patella size ranged from 20 mm to 41 mm. The most common patella sizes were 35 mm (27.6%), 32 mm (22.8%), and 38 mm (10.5%). These complications were seen with implants manufactured by 7 different companies (including multiple implant models from the same manufacturing company) and represented the complications of 39 different surgeons (Table 1). Type of injury (Table 2): When reviewing type of extensor mechanism injury, it was noted that injuries to the quadriceps tendon were the most common at 43.8% (46/105). Other soft tissue injuries included patellar tendon injuries at 20% (21/105) and retinacular tears in 8.6% (9/105). Patellar complications included patellar fracture in 13.3% (14/105) and issues involving the patellar button in 5.7% (6/105). The remaining 8.6% (9/105) knees involved two or more of the above mentioned components. Time to extensor mechanism injury (Table 2): The average time to injury after primary TKA was 264.3 days. This ranged from one intra-operative case (0 days) to 3099 days. The median time to injury was 70 days. Type of extensor mechanism repair (Table 2): Operative reports were reviewed for initial extensor mechanism repair/reconstruction surgery after ipsilateral TKA. Results showed the most common technique for surgical treatment was primary end to end repair with suture in 45.7% of patients (48/105). Patellar bone tunnels with suture fixation was seen in 27.6% (29/105). Less frequent methods of fixation included open reduction and internal fixation with revision of patellar button (8.6%, 9/105), open reduction and internal fixation with plate and screws (5.7%, 6/105), incorporation of allograft (3.8%, 4/105), use of suture anchors (3.8%, 4/105), or other style of procedures (4.8%, 5/105). The final outcomes reviewed (Table 3) looked at the average number of additional surgeries the ipsilateral knee required (1 being after initial extensor mechanism repair/reconstruction attempt), the number of knees that went on to have acute or chronic periprosthetic joint infection, the number of knees that went on to revision TKA, and the number of knees that went on to fusion of amputation. The average number of additional surgeries was 0.99 (range 0-8). Furthermore, 50/105 knees (47.6%) required at least 1 additional surgery. These additional surgeries included irrigation and debridement procedures, secondary attempts at extensor mechanism repair/reconstruction, revisions, fusions, and amputations. The number of infections was noted to be 17.1% (18/105). Revisions were seen in 33% (35/105) of patients. Lastly, 1 patient went on to knee fusion and 2 patients went on to have above knee amputations. Statistical analysis showed when comparing age, gender, BMI, and patellar implant size, there was no statistical significance in the need for additional surgeries, infection, revision, fusion, or amputation (Tables 4 and 5). Discussion This study set out to evaluate extensor mechanism injuries after primary TKA. During the study time period, 105 knees in 104 patients were recorded at a rate of 1.73%. Vijay et al. reviewed this topic as well, and quoted rates from 0.17%-2.7% of extensor mechanism injuries after TKA, which correlates with the findings in this study [5]. Regarding the type of injury patients sustained, quadriceps tendon injuries were the most common. This included 43.8% of patients from the pool of extensor mechanism injuries and only 0.76% of all primary TKA patients in the study time period. Comparatively, patellar tendon injuries made up 0.35% and patellar fractures/patellar button issues made up 0.33% of primary total knee complications. While there were no identifiable individual studies comparing the rates of the various extensor mechanism components and their rate of failure, individual studies have looked at the rate of each of their failures. Heer et al. quoted quadriceps tendon injuries after TKA at a rate of 0.1-1.1% of all total knees, fitting with these results (9). Additionally, Heer et al. performed a similar, but separate, study looking at patellar tendon injuries after TKA and referenced a rate of 0.17-1.0% [10]. While our study showed over twice as many quadriceps tendon tears compared to patellar tendon tears, the overall rate of each continues to fit with previously recorded data. Lastly, Sheth et al. looked at the rate of periprosthetic patellar fractures after TKA and showed a wider rate of 0.5-3% [11]. Our study showed a rate of 0.23% periprosthetic patellar fractures, which is slightly lower than previously reported rates. When including the 6 additional cases for patellar complications (patellar button loosening, maltracking, patellar button recall etc.), the rate becomes 0.33%, which is still lower than the quoted rate. However, this study only looked at patients who underwent surgical intervention for their extensor mechanism injury after primary TKA. Those who underwent non-operative management were not included. Additionally, this study only looked at patients who received their surgical treatment at one of the seven facilities within the one hospital system. Therefore, those who ended up in the care of other hospital systems, surgery centers, or were lost to follow-up were unable to be tracked or included. The inability to track patients who underwent non-operative treatment, treatment at a facility not included in the hospital system (I.e., unaffiliated surgery centers), or treatment by another surgeon outside of the included hospital system could only lead to underestimations in the quoted rates this study found regarding each type of extensor mechanism injury. The time to injury in our study was a mean of 264 days, which is comparative to previous studies showing a mean of 7 months or about 221 days [6]. There was one intra-operative patellar tendon injury included in our study. Including this injury as time 0, the range for the time to injury was 0-3099. With a large range of values, the median was noted to be 70 days, which may be more representative. Extensor mechanism injuries have historically been shown to be difficult to treat. Primary end to end repair has shown poor outcomes including increased extensor lag and increased rates of re-rupture [3]. Additionally, there has been evidence to show the use of allografts and/or mesh have more reliable outcomes with decreased rates of extensor lag and re-rupture [6]. Despite this evidence, our study showed the most common form of repair for soft tissue extensor mechanism injuries was direct end to end repair with suture (45.7%). This was quite high when comparing it to the use of adjunct fixation, such as allograft, mesh, or suture anchors. When combining all adjunct methods of fixation, their combined rate of 14.8% was 3 times less likely to be used on initial repair/reconstruction. While not specifically recorded, it was seen that repeat attempts for extensor mechanism repair/reconstruction was more likely to use adjunct methods. This study showed a high percentage of patients (47.6%) who required additional surgery after initial attempt to repair/reconstruct the peri-prosthetic extensor mechanism injury. Dobbs et al. in their study showed a rate of 23% of patients having failure of extensor mechanism repair in the setting of TKA. Furthermore, they specifically reported a re-tear rate amongst quadricep tendon repairs to be 40% [7]. While our study showed a higher rate of patients requiring at least one additional surgery (range 1-8 additional surgeries), this included all cause return to surgery for the ipsilateral knee, not only for re-injury to the extensor mechanism. As mentioned, patients returned to the operating room not only for re-tears, but also for irrigation and debridement, revision of implants, fusion, and above knee amputation. In our study, the high proportional rate of direct end to end repair with suture may have led to increased failures and therefore increased number of cases returning for additional surgery. Despite the literature supporting complete extensor mechanism allograft vs. Mesh allograft as the gold standard, this multi-center study showed surgeons still routinely attempt direct end-to-end repairs. It is speculated this is due to the easier technical demand of direct repair versus the technical demands of allograft reconstruction/augmentation. Additionally, another confounding variable may be the low rate of unresurfaced patellas. Our study population showed 103/105 knees (98%) had resurfaced patellas, which over this time period appears to be consistent with this region’s trend. While studies have shown leaving the patella unresurfaced leads to higher rates of revision surgeries [12], there has yet to be a high-powered study discussing if this step impacts extensor mechanism injuries. One study showed patella fractures after TKA with unresurfaced patella occurred at a rate of 0.05% [8]. Our study showed 0.23% of total knees had an eventual patella fracture that required surgical intervention. Our study also looked at the rate of infection, revision implant procedures, and the rates of amputation and fusion. According to national registry data, the rate of prosthetic joint infection after TKA is estimated to be 1.03% [13]. While there is limited literature to compare rates of prosthetic joint infection in the setting of extensor mechanism injury, our study showed a rate of 17.1%. While there are many variables that may contribute to this elevated rate, it highlights the increased risk for infection these patients may be predisposed to. Similarly, the rate of revision procedures performed was found in 33% of patients. Bloch et al. showed one of the most important factors associated with extensor mechanism injuries was malpositioning of the implants [3]. Critical evaluation in patients with these injuries should be performed including obtaining a thorough history regarding mechanism of injury and possible evaluation of component alignment, as these patients may be at higher risk for revision surgery. One patient went on to knee fusion and 2 went on to above-knee amputation, which highlights the most morbid endpoints in this setting. Of note, when comparing age, gender, BMI, and patellar implant size, there was no significant difference in the incidence of infection, need for revision of one or more implants components, nor need for additional surgeries. This may show that all patients are at increased risk for further complications, however further data would be required to support this. The strengths of this study include looking at a multi-center study, which was vastly inclusive to all orthopedic surgeons performing TKA, despite varying levels of training. There were few exclusion criteria in an effort to evaluate the wide variety of patients an arthroplasty surgeon may encounter. Furthermore, this study was able to perform an in-depth review of this cohort, comparing the different types of extensor mechanism injuries and their various treatment options with one study. This was something that previously was covered more broadly and required comparisons of patient populations from different studies. Finally, this study reviewed the general peri-prosthetic extensor mechanism repair/reconstruction techniques of this region. In regard to limitations, this study was performed as a retrospective chart review. Additionally, as mentioned prior, the results may be an underestimate due to patients being treated at facilities not sharing electronic medical records with the center included. There was no standardization of surgeon level of expertise, surgical technique, or extensor mechanism repair technique. Additionally, there was no record for review regarding post-operative protocols, limitations, satisfaction, or range of motion results. Conclusion In conclusion, this study continues to reinforce the poor outcomes associated with extensor mechanism injury after TKA. Patients undergoing TKA should be made aware of the potential risk and consequences of extensor mechanism injury. Additionally, those who unfortunately experience this complication should continue to have their expectations managed and stress the importance of the repair/reconstruction post-operative time period including weight bearing or motion restrictions and signs/symptoms of infection. From a clinical standpoint, this study exemplifies the high rate of complications with treatment of these injuries. Treating surgeons should use this information when deciding how to approach treating these injuries and avoid end-to-end direct repair attempts, but rather have a lower threshold to treat patients with extensor mechanism allograft (complete reconstruction or mesh augmentation). Overall, this topic includes a wide range of topics that would benefit from further investigation and further research is required to evaluate the various treatment options and their role in definitive patient outcomes and satisfaction. Abbreviations Total knee arthroplasty (TKA), quadriceps (quad) Declarations Ethics approval and consent to participate: Ethics approval was waived as all patient specific information was excluded from the study. Additionally, all research was performed in accordance with the Declaration of Helsinki. Human Ethics and Consent to Participate declarations: not applicable. Consent to Participate Declaration: N/A. Retrospective study with only chart review and no patient identification included. Availability of data and materials: The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Competing interests : The authors declare that they have no competing interests Funding : No funding to declare Clinical trial number : not applicable Authors' contributions: L.J and B.G. performed data collection, wrote the main manuscript text, and created the figures with the assistance of the statisticians department. D.M. was the principal investigator overseeing, editing, and writing manuscript. All authors reviewed the manuscript. Acknowledgements: Teresa Mccartney - Clinical Research Nurse. Karen Childers - Statistician References Shichman I, Roof M, Askew N, Nherera L, Rozell JC, Seyler TM, Schwarzkopf R. Projections and Epidemiology of Primary Hip and Knee Arthroplasty in Medicare Patients to 2040–2060. JB JS Open Access. 2023;8(1):e22.00112. 10.2106/JBJS.OA.22.00112 . PMID: 36864906; PMCID: PMC9974080. Tandogan RN, Terzi E, Gomez-Barrena E, Violante B, Kayaalp A. Extensor mechanism ruptures. EFORT Open Rev. 2022;7(6):384–95. 10.1530/EOR-22-0021 . PMID: 35638613; PMCID: PMC9257728. Ng J, Balcells-Nolla P, James PJ, Bloch BV. Extensor mechanism failure in total knee arthroplasty. EFORT Open Rev. 2021;6(3):181–8. 10.1302/2058-5241.6.200119 . PMID: 33841917; PMCID: PMC8025708. Rosenberg AG. Management of extensor mechanism rupture after TKA. J Bone Joint Surg Br. 2012;94(11 Suppl A):116-9. 10.1302/0301-620X.94B11.30823 . PMID: 23118397. Vaishya R, Agarwal AK, Vijay V. Extensor Mechanism Disruption after Total Knee Arthroplasty: A Case Series and Review of Literature. Cureus. 2016;8(2):e479. 10.7759/cureus.479 . PMID: 27004156; PMCID: PMC4780689. Barrack RLMD, Stanley, Tom BSE, Allen Butler RMD. Treating Extensor Mechanism Disruption After Total Knee Arthroplasty. Clinical Orthopaedics and Related Research 416():p 98–104, November 2003. | 10.1097/01.blo.0000092993.90435.69 Soong J, Silva A, Andrew TH. Disruption of quadriceps tendon after total knee arthroplasty: Case report of four cases. J Orthop Surg. 2017;25(2). 10.1177/2309499017717206 . Goldberg VM, Figgie HE 3rd, Inglis AE, Figgie MP, Sobel M, Kelly M, Kraay M. Patellar fracture type and prognosis in condylar total knee arthroplasty. Clin Orthop Relat Res. 1988;(236):115–22. PMID: 3180562. Heer S, O'Dowd, James &, Butler R, Dewitt D, Khanna, Gaurav, Mirzayan, Raffy. Quadriceps Tendon Rupture Following Total Knee Arthroplasty. Open Orthop J. 2019;13:250–4. 10.2174/1874325001913010250 . Heer S, O’Dowd J, Butler R, Dewitt D, Khanna, Gaurav, Mirzayan, Raffy. Patellar Tendon Rupture Following Total Knee Arthroplasty. Open Orthop J. 2019;13:239–43. 10.2174/1874325001913010239 . Sheth NPMD, Pedowitz DI, MS, MD1, Lonner JH. MD2. Periprosthetic Patellar Fractures. The Journal of Bone & Joint Surgery 89(10):p 2285–2296, October 2007. | 10.2106/JBJS.G.00132 Coory JA, Tan KG, Whitehouse SL, Hatton A, Graves SE, Crawford RW. The Outcome of Total Knee Arthroplasty With and Without Patellar Resurfacing up to 17 Years: A Report From the Australian Orthopaedic Association National Joint Replacement Registry. J Arthroplasty. 2020;35(1):132–8. Epub 2019 Aug 12. PMID: 31477541. Ahmed SS, Haddad FS. Prosthetic joint infection. Bone Joint Res. 2019;8(11):570–2. 10.1302/2046-3758.812.BJR-2019-0340 . PMID: 31832177; PMCID: PMC6888735. Tables Table 1 reviews patient characteristics included in this study. Age Mean 67.7 years Range 43–85 years Gender Male 35 Female 70 BMI Mean 34.99 Polyethylene Size 20 (mm) 1 (Number of patients) 24 1 25 4 26 1 27 6 28 2 29 8 30 2 31 3 32 24 33 1 34 3 35 29 37 2 38 11 40 3 41 1 Unknown 1 Unresurfaced 2 Company Stryker 50 (Number of patients) Not Reported 22 Zimmer Biomet 18 Smith and Nephew 9 Depuy 4 Microport 1 Exactech 1 Table 2 reviews the various extensor mechanism injuries, the time to injury, and the selected surgical fixation reported. Type of Extensor Mechanism Injury Quadriceps Tendon 46 Patellar Tendon 21 Retinacular Tears 9 Patella Fracture 14 Patellar Button Complications 6 2 or more components 9 Time to Extensor Mechanism Injury Mean 264.5 (days) Median 70 Range 0-3099 Type of Extensor Mechanism Fixation All Suture. Tendon to Tendon 48 Patellar Bone Tunnels and Suture 29 ORIF with Revision of Patella 9 ORIF with plate and screws 6 Suture Anchors 4 Allograft incorporation 4 Combination/Miscellaneous 5 Table 3 reviews the outcomes of patients with extensor mechanism injuries after TKA. Extra Surgeries Required Number of patients requiring additional surgery 50 (47.6%) Average number of extra surgeries 0.99 surgeries/patient Number of Infections 18 17.1% Number of Revision Arthroplasty Surgeries 35 33.3% Number of Knee Fusions 1 Number of Above Knee Amputations 2 Table 4 shows statistical analysis comparing Age, Gender, BMI, and patellar implant size in regards to risk of infection. There was no statistical significance among these characteristics and the risk of infection. Table 5 shows statistical analysis comparing Age, Gender, BMI, and patellar implant size in regards to risk of revision arthroplasty surgery. There was no statistical significance among these characteristics and the risk of revision. Additional Declarations No competing interests reported. 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. 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-5404800","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":383203219,"identity":"b76e9792-82f8-4d7b-bebb-d555faf1c91a","order_by":0,"name":"Lawrence Jajou","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABSklEQVRIie2PPUvDQBiA3xBIl6u3XhHMX3hDoSqE4k9pCGTyIyBINxMK51LtmuCfUAri5kmgXUK7FrK0dBZTCmJBwWspaEoUR8E80917PDzvARQU/EG2Po8CEMBcX9y9BoDqqTmKtqE46wsyqSh+62dlRfQLpRTX0tl9fQeUaOzO+FCn21GPpciOaenxYuqCeaIfZBVyWA3D2K4C9NAIeWKEV45TCZCdVtqW3wrA2b8VG4sdddUyF5YHAqtlnjQwJrWEILNuhFQIRGh4WYU+ddV3Ls496KdSGUiFviRvUnkYTvIVJisKF/Kz8bIilhUtgWWFrSv6xvfZ81y55LbBIXaNYGAbYVvbXbSlEowm/jVBBzGrUOrYsOB1nbL+HaZn8kDUKb42TavTscWcNE3Us4t9yQkNc+ZyhiJnvup56jj/5btKQUFBwX/hA6N5dF5tFImLAAAAAElFTkSuQmCC","orcid":"","institution":"Corewell Health East Farmington Hills","correspondingAuthor":true,"prefix":"","firstName":"Lawrence","middleName":"","lastName":"Jajou","suffix":""},{"id":383203220,"identity":"7b9ba830-7a31-4f42-9996-979511492165","order_by":1,"name":"Brian Golasa","email":"","orcid":"","institution":"Corewell Health East Farmington Hills","correspondingAuthor":false,"prefix":"","firstName":"Brian","middleName":"","lastName":"Golasa","suffix":""},{"id":383203221,"identity":"44eeaaee-76b1-49e8-860d-53dae87fa925","order_by":2,"name":"Daniel McCall","email":"","orcid":"","institution":"Corewell Health East Farmington Hills","correspondingAuthor":false,"prefix":"","firstName":"Daniel","middleName":"","lastName":"McCall","suffix":""}],"badges":[],"createdAt":"2024-11-06 17:53:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5404800/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5404800/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":71629094,"identity":"bca0aa11-a69a-4d50-a258-10dbf267167d","added_by":"auto","created_at":"2024-12-17 09:18:35","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":19905,"visible":true,"origin":"","legend":"\u003cp\u003edemonstrates the patient selection process. Initial patient selection began with all total knee arthroplasty procedures within the study time period. This was then filtered down to the relevant patient population.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5404800/v1/db34436470a2f32edea07e81.png"},{"id":71858234,"identity":"5436569e-a5ed-471f-b428-fc864777ae12","added_by":"auto","created_at":"2024-12-19 08:32:55","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":538001,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5404800/v1/71aa2804-a5e3-4bb1-adc3-5ee2bda6b832.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Extensor Mechanism Injuries after Primary Total Knee Arthroplasty","fulltext":[{"header":"Background/Introduction","content":"\u003cp\u003ePrimary total knee arthroplasty (TKA) continues to become a more common surgery in the orthopedic community. With projections of primary TKA estimated to continually increase[1], it can be presumed that there will also be a rise in extensor mechanism injuries. Therefore, understanding the technique, outcomes, complications, and the way these are treated remains imperative. Specifically, extensor mechanism injuries can be a devastating complication to primary TKA and pose as a difficult complication to manage. While extensor mechanism injuries occur in about 0.17-2.5% of primary total knees, they pose difficulty in treatment and worse patient outcomes [2], [4]. Injury to the extensor mechanism includes damage to the quadriceps tendon, patella, patellar tendon, or retinaculum that aid in extension of the knee. History has shown that outcomes after conservatively treated extensor mechanism injuries in the setting of TKA are extremely poor, and therefore this is reserved for the low function, low demand, elderly population [3]. For the vast majority of these patients, surgical intervention is indicated. The presence of a TKA prosthesis can make surgical treatment of extensor mechanism injuries more difficult due to potential stiffness, scar tissue, decreased bone stock, and presence of a patellar component, which may limit treatment options. Additionally, studies have shown that these injuries routinely do poorly with lower functional outcomes and patient satisfaction scores when compared to uncomplicated TKA (3). Surgical treatment varies depending on the type and severity of the injury. Soft tissue structures can undergo repair versus reconstruction, with some literature favoring reconstruction with the use of cadaveric or synthetic grafts [4]. Patellar fractures can be treated with open reduction and internal fixation, revision of the patellar component, or patellectomy. Despite the various treatment options, there is no one treatment option for each extensor mechanism injury after TKA. With the rise of TKA procedures it is important to understand the various treatment options and their outcomes. This study aims to evaluate the rate and sequelae of extensor mechanism injuries after TKA in a cohort of patients.\u003c/p\u003e"},{"header":"Materials And Methods","content":"\u003cp\u003eUsing the William Beaumont clinical research database (CRDB) (including all 7 of the system\u0026rsquo;s hospitals in Michigan), all patients who underwent primary TKA from January 1, 2015, to December 31, 2022, were obtained. These patients were then evaluated for subsequent operative encounters within the Beaumont Health system for extensor mechanism injuries to the ipsilateral leg as the TKA. Extensor mechanism injury included any injury to the quadriceps tendon, patellar tendon, patellar bone, patellar polyethylene, or retinaculum. Inclusion criteria were patients who underwent primary TKA within the above time period and age 18 or older at the time of index surgery. Exclusion criteria included patients having undergone TKA prior to the time period of study, patients below the age of 18 at the time of index surgery, revision total knee arthroplasty prior to extensor mechanism injury, and patients with known ipsilateral extensor mechanism injury prior to primary total knee arthroplasty. Once patients who had subsequent extensor mechanism injuries were isolated via the CRDB (Figure 1), chart review was then used to identify baseline patient characteristics, time to extensor mechanism injury, type of extensor mechanism injury, patellar implant specifications, and extensor mechanism surgical fixation type. Baseline patient characteristics recorded included gender, age, and BMI. Additionally, it was evaluated whether patients required further surgeries to the ipsilateral knee, treatment for infection, revision (of at least 1 component) of the TKA, or if patient went on to require fusion or amputation. Lastly, comparisons were secondarily made regarding extensor mechanism injury and patellar size, gender, age, BMI, and number of additional surgeries.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical Analysis\u003c/strong\u003e: Univariate analyses were conducted to evaluate the association between patient characteristics and the outcomes of incidence of infection (Table 4) and injury knee (Table 5). Patient characteristics were stratified by outcome and compared using Mann-Whitney U tests for continuous variables and Pearson\u0026rsquo;s Chi-Squared tests for categorical variables. Spearman\u0026rsquo;s rank correlation coefficient (\u003cstrong\u003e\u0026rho;\u003c/strong\u003e) was computed to assess the correlation between number of extra surgeries and age, BMI and patella implant size respectively. The correlation coefficients indicated negligible to weak correlations and were not statistically significant (Age:\u003cstrong\u003e\u0026nbsp;\u0026rho;\u003c/strong\u003e) = -0.06, p = 0.543; BMI: (\u003cstrong\u003e\u0026rho;\u003c/strong\u003e) = 0.01, p = 0.937; Size: (\u003cstrong\u003e\u0026rho;)\u0026nbsp;\u003c/strong\u003e= 0.13, p = 0.208).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e6064 primary TKA procedures were found from January 1, 2015 to December 31, 2022. Of these, 105 knees in 104 patients were found to have surgical intervention on the ipsilateral extensor mechanism (Figure 1). The average age was 67.7 years (43-85). There were 70 female knees and 35 male knees included in this study. The last patient characteristic reviewed was BMI, which averaged 34.99 (18.0-60.17). In regard to implants, the patella was resurfaced in 103/105 knees (98%). Patella size ranged from 20 mm to 41 mm. The most common patella sizes were 35 mm (27.6%), 32 mm (22.8%), and 38 mm (10.5%). These complications were seen with implants manufactured by 7 different companies (including multiple implant models from the same manufacturing company) and represented the complications of 39 different surgeons (Table 1).\u003c/p\u003e\n\u003cp\u003eType of injury (Table 2): When reviewing type of extensor mechanism injury, it was noted that injuries to the quadriceps tendon were the most common at 43.8% (46/105). Other soft tissue injuries included patellar tendon injuries at 20% (21/105) and retinacular tears in 8.6% (9/105). Patellar complications included patellar fracture in 13.3% (14/105) and issues involving the patellar button in 5.7% (6/105). The remaining 8.6% (9/105) knees involved two or more of the above mentioned components.\u003c/p\u003e\n\u003cp\u003eTime to extensor mechanism injury (Table 2): The average time to injury after primary TKA was 264.3 days. This ranged from one intra-operative case (0 days) to 3099 days. The median time to injury was 70 days.\u003c/p\u003e\n\u003cp\u003eType of extensor mechanism repair (Table 2): Operative reports were reviewed for initial extensor mechanism repair/reconstruction surgery after ipsilateral TKA. Results showed the most common technique for surgical treatment was primary end to end repair with suture in 45.7% of patients (48/105). Patellar bone tunnels with suture fixation was seen in 27.6% (29/105). Less frequent methods of fixation included open reduction and internal fixation with revision of patellar button (8.6%, 9/105), open reduction and internal fixation with plate and screws (5.7%, 6/105), incorporation of allograft (3.8%, 4/105), use of suture anchors (3.8%, 4/105), or other style of procedures (4.8%, 5/105).\u003c/p\u003e\n\u003cp\u003eThe final outcomes reviewed (Table 3) looked at the average number of additional surgeries the ipsilateral knee required (1 being after initial extensor mechanism repair/reconstruction attempt), the number of knees that went on to have acute or chronic periprosthetic joint infection, the number of knees that went on to revision TKA, and the number of knees that went on to fusion of amputation. The average number of additional surgeries was 0.99 (range 0-8). Furthermore, 50/105 knees (47.6%) required at least 1 additional surgery. These additional surgeries included irrigation and debridement procedures, secondary attempts at extensor mechanism repair/reconstruction, revisions, fusions, and amputations. The number of infections was noted to be 17.1% (18/105). Revisions were seen in 33% (35/105) of patients. Lastly, 1 patient went on to knee fusion and 2 patients went on to have above knee amputations. Statistical analysis showed when comparing age, gender, BMI, and patellar implant size, there was no statistical significance in the need for additional surgeries, infection, revision, fusion, or amputation (Tables 4 and 5).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study set out to evaluate extensor mechanism injuries after primary TKA. During the study time period, 105 knees in 104 patients were recorded at a rate of 1.73%. Vijay et al. reviewed this topic as well, and quoted rates from 0.17%-2.7% of extensor mechanism injuries after TKA, which correlates with the findings in this study [5].\u003c/p\u003e\n\u003cp\u003eRegarding the type of injury patients sustained, quadriceps tendon injuries were the most common. This included 43.8% of patients from the pool of extensor mechanism injuries and only 0.76% of all primary TKA patients in the study time period. Comparatively, patellar tendon injuries made up 0.35% and patellar fractures/patellar button issues made up 0.33% of primary total knee complications. While there were no identifiable individual studies comparing the rates of the various extensor mechanism components and their rate of failure, individual studies have looked at the rate of each of their failures. Heer et al. quoted quadriceps tendon injuries after TKA at a rate of 0.1-1.1% of all total knees, fitting with these results (9). Additionally, Heer et al. performed a similar, but separate, study looking at patellar tendon injuries after TKA and referenced a rate of 0.17-1.0% [10]. While our study showed over twice as many quadriceps tendon tears compared to patellar tendon tears, the overall rate of each continues to fit with previously recorded data. Lastly, Sheth et al. looked at the rate of periprosthetic patellar fractures after TKA and showed a wider rate of 0.5-3% [11]. Our study showed a rate of 0.23% periprosthetic patellar fractures, which is slightly lower than previously reported rates. When including the 6 additional cases for patellar complications (patellar button loosening, maltracking, patellar button recall etc.), the rate becomes 0.33%, which is still lower than the quoted rate. However, this study only looked at patients who underwent surgical intervention for their extensor mechanism injury after primary TKA. Those who underwent non-operative management were not included. Additionally, this study only looked at patients who received their surgical treatment at one of the seven facilities within the one hospital system. Therefore, those who ended up in the care of other hospital systems, surgery centers, or were lost to follow-up were unable to be tracked or included. The inability to track patients who underwent non-operative treatment, treatment at a facility not included in the hospital system (I.e., unaffiliated surgery centers), or treatment by another surgeon outside of the included hospital system could only lead to underestimations in the quoted rates this study found regarding each type of extensor mechanism injury.\u003c/p\u003e\n\u003cp\u003eThe time to injury in our study was a mean of 264 days, which is comparative to previous studies showing a mean of 7 months or about 221 days [6]. There was one intra-operative patellar tendon injury included in our study. Including this injury as time 0, the range for the time to injury was 0-3099. With a large range of values, the median was noted to be 70 days, which may be more representative.\u003c/p\u003e\n\u003cp\u003eExtensor mechanism injuries have historically been shown to be difficult to treat. Primary end to end repair has shown poor outcomes including increased extensor lag and increased rates of re-rupture [3]. Additionally, there has been evidence to show the use of allografts and/or mesh have more reliable outcomes with decreased rates of extensor lag and re-rupture [6]. Despite this evidence, our study showed the most common form of repair for soft tissue extensor mechanism injuries was direct end to end repair with suture (45.7%). This was quite high when comparing it to the use of adjunct fixation, such as allograft, mesh, or suture anchors. When combining all adjunct methods of fixation, their combined rate of 14.8% was 3 times less likely to be used on initial repair/reconstruction. While not specifically recorded, it was seen that repeat attempts for extensor mechanism repair/reconstruction was more likely to use adjunct methods.\u003c/p\u003e\n\u003cp\u003eThis study showed a high percentage of patients (47.6%) who required additional surgery after initial attempt to repair/reconstruct the peri-prosthetic extensor mechanism injury. Dobbs et al. in their study showed a rate of 23% of patients having failure of extensor mechanism repair in the setting of TKA. Furthermore, they specifically reported a re-tear rate amongst quadricep tendon repairs to be 40% [7]. While our study showed a higher rate of patients requiring at least one additional surgery (range 1-8 additional surgeries), this included all cause return to surgery for the ipsilateral knee, not only for re-injury to the extensor mechanism. As mentioned, patients returned to the operating room not only for re-tears, but also for irrigation and debridement, revision of implants, fusion, and above knee amputation. In our study, the high proportional rate of direct end to end repair with suture may have led to increased failures and therefore increased number of cases returning for additional surgery. Despite the literature supporting complete extensor mechanism allograft vs. Mesh allograft as the gold standard, this multi-center study showed surgeons still routinely attempt direct end-to-end repairs. It is speculated this is due to the easier technical demand of direct repair versus the technical demands of allograft reconstruction/augmentation. Additionally, another confounding variable may be the low rate of unresurfaced patellas. Our study population showed 103/105 knees (98%) had resurfaced patellas, which over this time period appears to be consistent with this region\u0026rsquo;s trend. While studies have shown leaving the patella unresurfaced leads to higher rates of revision surgeries [12], there has yet to be a high-powered study discussing if this step impacts extensor mechanism injuries. One study showed patella fractures after TKA with unresurfaced patella occurred at a rate of 0.05% [8]. Our study showed 0.23% of total knees had an eventual patella fracture that required surgical intervention.\u003c/p\u003e\n\u003cp\u003eOur study also looked at the rate of infection, revision implant procedures, and the rates of amputation and fusion. According to national registry data, the rate of prosthetic joint infection after TKA is estimated to be 1.03% [13]. While there is limited literature to compare rates of prosthetic joint infection in the setting of extensor mechanism injury, our study showed a rate of 17.1%. While there are many variables that may contribute to this elevated rate, it highlights the increased risk for infection these patients may be predisposed to. Similarly, the rate of revision procedures performed was found in 33% of patients. Bloch et al. showed one of the most important factors associated with extensor mechanism injuries was malpositioning of the implants [3]. Critical evaluation in patients with these injuries should be performed including obtaining a thorough history regarding mechanism of injury and possible evaluation of component alignment, as these patients may be at higher risk for revision surgery. One patient went on to knee fusion and 2 went on to above-knee amputation, which highlights the most morbid endpoints in this setting.\u003c/p\u003e\n\u003cp\u003eOf note, when comparing age, gender, BMI, and patellar implant size, there was no significant difference in the incidence of infection, need for revision of one or more implants components, nor need for additional surgeries. This may show that all patients are at increased risk for further complications, however further data would be required to support this.\u003c/p\u003e\n\u003cp\u003eThe strengths of this study include looking at a multi-center study, which was vastly inclusive to all orthopedic surgeons performing TKA, despite varying levels of training. There were few exclusion criteria in an effort to evaluate the wide variety of patients an arthroplasty surgeon may encounter. Furthermore, this study was able to perform an in-depth review of this cohort, comparing the different types of extensor mechanism injuries and their various treatment options with one study. This was something that previously was covered more broadly and required comparisons of patient populations from different studies. Finally, this study reviewed the general peri-prosthetic extensor mechanism repair/reconstruction techniques of this region.\u003c/p\u003e\n\u003cp\u003eIn regard to limitations, this study was performed as a retrospective chart review. Additionally, as mentioned prior, the results may be an underestimate due to patients being treated at facilities not sharing electronic medical records with the center included. There was no standardization of surgeon level of expertise, surgical technique, or extensor mechanism repair technique. Additionally, there was no record for review regarding post-operative protocols, limitations, satisfaction, or range of motion results.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn conclusion, this study continues to reinforce the poor outcomes associated with extensor mechanism injury after TKA. Patients undergoing TKA should be made aware of the potential risk and consequences of extensor mechanism injury. Additionally, those who unfortunately experience this complication should continue to have their expectations managed and stress the importance of the repair/reconstruction post-operative time period including weight bearing or motion restrictions and signs/symptoms of infection. From a clinical standpoint, this study exemplifies the high rate of complications with treatment of these injuries. Treating surgeons should use this information when deciding how to approach treating these injuries and avoid end-to-end direct repair attempts, but rather have a lower threshold to treat patients with extensor mechanism allograft (complete reconstruction or mesh augmentation). Overall, this topic includes a wide range of topics that would benefit from further investigation and further research is required to evaluate the various treatment options and their role in definitive patient outcomes and satisfaction.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eTotal knee arthroplasty (TKA), quadriceps (quad)\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cem\u003eEthics approval and consent to participate:\u003c/em\u003e Ethics approval was waived as all patient specific information was excluded from the study. Additionally, all research was performed in accordance with the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003eHuman Ethics and Consent to Participate declarations: not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eConsent to Participate Declaration: N/A.\u0026nbsp;\u003c/em\u003eRetrospective study with only chart review and no patient identification included.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAvailability of data and materials:\u003c/em\u003e The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eCompeting interests\u003c/em\u003e: The authors declare that they have no competing interests\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eFunding\u003c/em\u003e: No funding to declare\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eClinical trial number\u003c/em\u003e: not applicable\u003c/p\u003e\n\u003cp\u003eAuthors\u0026apos; contributions: L.J and B.G. performed data collection, wrote the main manuscript text, and created the figures with the assistance of the statisticians department. D.M. was the principal investigator overseeing, editing, and writing manuscript. All authors reviewed the manuscript.\u003c/p\u003e\n\u003cp\u003eAcknowledgements: Teresa Mccartney - Clinical Research Nurse. Karen Childers - Statistician\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eShichman I, Roof M, Askew N, Nherera L, Rozell JC, Seyler TM, Schwarzkopf R. Projections and Epidemiology of Primary Hip and Knee Arthroplasty in Medicare Patients to 2040\u0026ndash;2060. JB JS Open Access. 2023;8(1):e22.00112. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.2106/JBJS.OA.22.00112\u003c/span\u003e\u003cspan address=\"10.2106/JBJS.OA.22.00112\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. PMID: 36864906; PMCID: PMC9974080.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTandogan RN, Terzi E, Gomez-Barrena E, Violante B, Kayaalp A. Extensor mechanism ruptures. 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The Outcome of Total Knee Arthroplasty With and Without Patellar Resurfacing up to 17 Years: A Report From the Australian Orthopaedic Association National Joint Replacement Registry. J Arthroplasty. 2020;35(1):132\u0026ndash;8. Epub 2019 Aug 12. PMID: 31477541.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAhmed SS, Haddad FS. Prosthetic joint infection. Bone Joint Res. 2019;8(11):570\u0026ndash;2. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1302/2046-3758.812.BJR-2019-0340\u003c/span\u003e\u003cspan address=\"10.1302/2046-3758.812.BJR-2019-0340\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. PMID: 31832177; PMCID: PMC6888735.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cdiv class=\"gridtable\"\u003e\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ereviews patient characteristics included in this study.\u003c/div\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eAge\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eMean\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e67.7 years\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eRange\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e43\u0026ndash;85 years\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eGender\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eMale\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e35\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eFemale\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e70\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eBMI\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eMean\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e34.99\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePolyethylene Size\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e20 (mm)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1 (Number of patients)\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e24\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e25\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e4\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e26\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e27\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e6\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e28\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e2\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e29\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e8\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e30\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e2\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e31\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e3\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e32\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e24\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e33\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e34\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e3\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e35\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e29\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e37\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e2\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e38\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e11\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e40\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e3\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e41\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eUnknown\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eUnresurfaced\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e2\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eCompany\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eStryker\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e50 (Number of patients)\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eNot Reported\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e22\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eZimmer Biomet\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e18\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eSmith and Nephew\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e9\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eDepuy\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e4\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eMicroport\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eExactech\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ereviews the various extensor mechanism injuries, the time to injury, and the selected surgical fixation reported.\u003c/div\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eType of Extensor Mechanism Injury\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eQuadriceps Tendon\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e46\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePatellar Tendon\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e21\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eRetinacular Tears\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e9\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePatella Fracture\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e14\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePatellar Button Complications\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e6\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e2 or more components\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e9\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eTime to Extensor Mechanism Injury\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eMean\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e264.5 (days)\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eMedian\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e70\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eRange\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0-3099\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eType of Extensor Mechanism Fixation\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eAll Suture. Tendon to Tendon\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e48\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePatellar Bone Tunnels and Suture\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e29\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eORIF with Revision of Patella\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e9\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eORIF with plate and screws\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e6\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eSuture Anchors\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e4\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eAllograft incorporation\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e4\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eCombination/Miscellaneous\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e5\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ereviews the outcomes of patients with extensor mechanism injuries after TKA.\u003c/div\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eExtra Surgeries Required\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eNumber of patients requiring additional surgery\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e50 (47.6%)\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eAverage number of extra surgeries\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.99 surgeries/patient\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eNumber of Infections\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e18\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e17.1%\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eNumber of Revision Arthroplasty Surgeries\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e35\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e33.3%\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eNumber of Knee Fusions\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eNumber of Above Knee Amputations\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e2\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\u003cstrong\u003eTable 4\u003c/strong\u003e shows statistical analysis comparing Age, Gender, BMI, and patellar implant size in regards to risk of infection. There was no statistical significance among these characteristics and the risk of infection.\u003c/div\u003e\n\u003cp\u003e\u003cimg src=\"https://myfiles.space/user_files/58894_9946feeafa4c1df7/58894_custom_files/img1732897400.png\" width=\"608\" height=\"352\"\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 5\u0026nbsp;\u003c/strong\u003eshows statistical analysis comparing Age, Gender, BMI, and patellar implant size in regards to risk of revision arthroplasty surgery. There was no statistical significance among these characteristics and the risk of revision.\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"https://myfiles.space/user_files/58894_9946feeafa4c1df7/58894_custom_files/img1732897454.png\" width=\"689\" height=\"406\"\u003e\u003cbr\u003e\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","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":"Extensor Mechanism, Quadriceps, Patella, Tendon, Total Knee Arthroplasty","lastPublishedDoi":"10.21203/rs.3.rs-5404800/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5404800/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e: Extensor mechanism injuries after total knee arthroplasty (TKA) continue to be a difficult complication to treat and can be associated with devastating outcomes. This study attempts to review the prevalence, treatment types, and outcomes of extensor mechanism injuries after total knee arthroplasty within a cohort of patients.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e: Using a clinical research database, a retrospective cohort study was performed via chart review of patients who underwent a total knee arthroplasty over the course of 7 years from 7 hospitals within the same hospital system. The charts were then screened for subsequent operative repair of the ipsilateral extensor mechanism at a later date. Patient characteristics, implants, type of extensor mechanism injury, fixation type, subsequent surgeries were evaluated.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e: Of the 6064 total knee arthroplasties, 104 patients with 105 (1.73%) knees went on to have extensor mechanism injuries. Quadriceps tendon injuries were the most common, followed by patellar tendon, and then patella fractures. Median time to injury was 70 days. Patients requiring additional surgery beyond initial repair of extensor mechanism injury was 47.6% (50/105). Additionally, 33% (35/105) went on to have revision of component(s) and 17.1% (18-105) received treatment for prosthetic joint infection.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e: While overall rare, extensor mechanism injuries after total knee arthroplasty can pose serious complications beyond initial repair, including need for additional surgery, infection, revision, and even amputation. Careful consideration should be taken by the treating surgeon when faced with these injuries to avoid further complications.\u003c/p\u003e","manuscriptTitle":"Extensor Mechanism Injuries after Primary Total Knee Arthroplasty","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-12-17 09:18:30","doi":"10.21203/rs.3.rs-5404800/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":"44eec7f4-dc57-4025-bf5c-068cdea5fa05","owner":[],"postedDate":"December 17th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-12-19T08:24:31+00:00","versionOfRecord":[],"versionCreatedAt":"2024-12-17 09:18:30","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5404800","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5404800","identity":"rs-5404800","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}