Survivorship of Extensor Mechanism Allograft Reconstruction After Total Knee Arthroplasty

A unique case report of a revision extensor mechanism reconstruction using Marlex mesh in the setting of proximal tibial bone deficiency: The tantalum clamshell technique

Extensor mechanism (EM) disruption is a rare but severe complication of total knee arthroplasty (TKA) that can greatly impair function. Treatment options for chronic patella tendon ruptures include primary repair, autograft augmentation, and reconstruction with allograft or synthetic material. Despite various techniques, failures can occur, and options for reconstruction after a failed allograft or mesh are limited, especially if the tibial component is well-fixed and cannot be easily removed, and if there is proximal tibial deficiency from a previous failed EM allograft. This case report presents a novel solution for revision EM reconstruction in a 72y.o. female patient with a history of multiple EM failures using an off-label Trabecular Metal Cone-Mesh-Cone (TM CMC) clamshell construct. The surgical procedure involved the removal of a non-viable allograft from the knee joint and the creation of a custom trabecular metal (TM) clamshell construct with a Marlex mesh graft in between the two TM implants. The customized TM cone was designed to cover the deficient anterior tibia and wrap around the ingrown TM cone. The Marlex mesh was cemented between the existing implant and the customized TM cone, and the construct was secured in place with two cancellous screws. The mesh was tunneled between soft tissue to prevent contact with the implant and rotated scar tissue was interposed to prevent abrasion of the mesh on the implant surfaces. The patient tolerated the procedure well and no complications were noted postoperatively. At a follow-up 12 months after the operation the patient remains satisfied with the result.

Marlex Mesh Reconstruction of the Extensor Mechanism: A Concise 5-Year Follow-up of 2 Previous Reports

LEVEL OF EVIDENCE

Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Allograft or Synthetic Mesh Extensor Mechanism Reconstruction After TKA Carries a High Risk of Infection, Revision, and Extensor Lag

BACKGROUND

Extensor mechanism disruption is a devastating complication after TKA. Extensor mechanism reconstruction can be performed using an allograft or synthetic mesh. Recent studies have disagreed about the durability of these reconstructions. Evaluating a larger series of reconstructions that use current popular techniques and principles provides information to guide patient and surgeon expectations while bringing to light the potential fate of patients who experience an infection postoperatively.

QUESTIONS/PURPOSES

(1) What was the 5-year survival free of repeat revision surgery or persistent extensor lag of more than 30° after allograft or synthetic mesh reconstruction of extensor mechanism disruptions after TKA, and did this differ between techniques? (2) What was the 5-year survival free of infection after allograft or mesh reconstruction, and what proportion of those patients experienced a secondary severe complication (arthrodesis or amputation)?

METHODS

Between April 2008 and December 2020, 123 patients underwent extensor mechanism reconstruction after TKA at one center. Of those, 37% (45) were lost to follow-up before 2 years, had not been seen in the past 5 years, did not reach a study endpoint (repeat revision or extensor lag > 30°) before that time, or underwent primary repair and thus could not be analyzed, leaving 63% (78) for analysis here. During the study period, we considered extensor mechanism surgery when acute or chronic disruption of the patellar or quadriceps tendon was present or there was a fracture of the patella resulting in extensor lag. The decision to use either mesh or an allograft largely depended on surgeon experience and familiarity with either technique. We collected patient demographics, operative details (location of disruption and presence of a hinged prosthesis), subsequent periprosthetic joint infection (PJI), and postoperative SF-12 and Knee Injury and Osteoarthritis Outcome Score, Joint Replacement, scores. We used Kaplan-Meier survivorship analysis, with endpoints of extensor lag more than 30° or revision of the reconstruction and PJI. The mean follow-up duration was 5.3 ± 3.2 years.

RESULTS

Survivorship free from revision or recurrent extensor lag was 54% (95% CI 44% to 66%) at 5 years. There was no difference between those undergoing reconstruction with allografts and those with mesh in terms of survivorship free from those endpoints at that timepoint (52% [95% CI 40% to 68%] versus 57% [95 CI% 41 to 78%]; p = 0.99). Survivorship free from PJI was 81% (95% CI 73% to 90%) at 2 years. There was no difference between those with allografts and those with mesh in terms of survivorship free from PJI at that timepoint (79% [95% CI 69% to 92%] versus 83% [95% CI 71% to 98%]; p = 0.75). Of the 17 patients who experienced PJI, four ultimately underwent arthrodesis and three more underwent transfemoral amputation.

CONCLUSION

Allograft and synthetic mesh reconstructions commonly left patients with persistent limb dysfunction, while several patients had PJI and some underwent salvage procedures. Although improvements have been made with regard to treating extensor mechanism disruptions, patients and surgeons should be well aware of the potential adverse outcomes when determining management and use these findings to conduct risk-benefit analyses. There is a need for future studies to identify protocols that improve the durability of reconstructions and to determine whether interventions such as prolonged prophylactic antibiotic therapy have a role in minimizing the risk of PJI.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Extensor Mechanism Disruption Remains a Challenging Problem

BACKGROUND

Extensor mechanism disruption (EMD) following total knee arthroplasty (TKA) is a devastating problem commonly treated with allograft or synthetic reconstruction. Understanding of reconstruction success rates and patient recorded outcomes is lacking.

METHODS

Patients who have an EMD after TKA undergoing mesh or whole-extensor allograft reconstruction between 2011 and 2019, with minimum 2-year follow-up were reviewed at two tertiary care centers. Functional failure was defined as extensor lag >30 degrees, amputation, or fusion, as well as revision extensor mechanism reconstruction (EMR). Survivorship was assessed using Kaplan-Meier curves, and factors for success were determined with logistic regressions.

RESULTS

Of fifty-six EMRs (49 patients), 50.0% (28/56) were functionally successful at 3.2 years of mean follow-up (range, 0.2 to 7.4). In situ survivorship of the reconstructions at 36 months was 75.0% (42 of 58). There were 50.0% (14 of 28) of functionally failed EMRs that retained their reconstruction at last follow-up. Mean extensor lag among successes and failures was 5.4 and 71.0° (P = .01), respectively. Mean Knee Injury and Osteoarthritis Outcome Score, Joint Replacement scores were 67.1 and 48.8 among successes and failures (P = .01). There were 64.0% (16 of 25) of successes and 1 of 19 failures that obtained a Knee Injury and Osteoarthritis Outcome Score, Joint Replacement score above the minimum patient-acceptable symptom state for TKA. Survivorship and success rates were similar between reconstruction methods (P = .86; P = .76). All-cause mortality was 8.2% (4 of 49), each with EMR failure prior to death. All-cause reoperation rate was 42.9% (24 of 56), with a 14.3% (8 of 56) rate of revision EMR and 10.7% (6 of 56) rate of above-knee-amputation or modular fusion.

CONCLUSIONS

This multicenter investigation of mesh or allograft EMR demonstrated modest functional success at 3.2 years. Complication and reoperation rates were high, regardless of EMR technique. Therefore, EMD after TKA remains problematic.

High rate of failure after revision extensor mechanism allograft reconstruction

BACKGROUND

Patients who fail initial extensor mechanism allograft (EMA) reconstruction for extensor mechanism disruption after total knee arthroplasty (TKA) are left with few options. This study evaluated outcomes in patients that underwent revision EMA reconstruction following a failed EMA.

METHOD

Ten patients that underwent revision EMA for failed index EMA with minimum 1-year follow-up were retrospectively reviewed. Patients receiving fresh-frozen EMA (quadriceps tendon, patella, patellar tendon, and tibial tubercle) at index and revision EMA were included. The primary outcome was EMA failure defined as revision surgery, extensor lag > 30°, or Knee Society Score (KSS) < 60 at last follow-up. Descriptive statistics were performed, with p < 0.05.

RESULTS

Mean extensor lag improved from 55.6°±26.7° pre-revision to 32.8°±29.6° (p = 0.13) at mean follow-up of 43.8 months (range, 12-124 months). Mean KSS improved from 41.0 ± 9.5 pre-revision to 73.4 ± 14.5 at last follow-up (p < 0.001). All patients required assistive devices for ambulation at final follow-up: one (10.0%) required a wheelchair, five (50.0%) required a walker, and four (40.0%) required a cane. Seven (70.0%) patients experienced EMA failure at a mean of 33.6 months (range, 2-124) following revision EMA: three (30.0%) were revised for periprosthetic joint infection (one of which also had extensor lag > 30°), three (30.0%) additional patients had extensor lag > 30°, and one (10.0%) patient had KSS < 60 (this patient developed PJI and was treated nonoperatively with chronic antibiotic suppression).

CONCLUSIONS

Revision EMA reconstruction fails at a high rate despite leading to improvements in KSS. Further research is needed to develop effective prevention and treatment strategies for failure after initial EMA reconstruction.

Inferior results at long-term follow-up after extensor mechanism allograft reconstruction in septic compared to aseptic revision total knee arthroplasty

PURPOSE

Extensor mechanism lesion after total knee arthroplasty (TKA) is a catastrophic complication. Reconstruction with extensor mechanism allograft (EMA) has been described as a sound salvage procedure. Its effectiveness at long term and in septic cases is still under scrutiny. The long-term results of EMA reconstruction for chronic extensor mechanism failures following aseptic and septic revision TKA have been analysed.

METHODS

From the institutional database, 35 patients with a revision TKA (RevTKA) undergoing EMA reconstruction from 2005 to 2015 have been retrospectively identified. A history of periprosthetic joint infection (PJI) was found in 13 (37%) patients. The mean follow-up was 81.2 months (± 34.7, range 3-120). EMA failures were considered for lag more than 20°, Knee Society Score (KSS) less than 60 points, and/or in the case of revision of the allograft.

RESULTS

The mean KSS improved from 35.9 (± 16.9, range 0-54) to 86.6 (± 10.4, range 54-99) points in the aseptic group (p < 0.001) and from 27.5 (± 11.6, range 10-44) to 79.4 (± 16.3, range 48-94) points in the septic group (p < 0.001). The extensor lag changed from 48.4° (± 14.5, range 30-90) to 4.6° (± 10.8, range 0-50) in the aseptic group (p < 0.001) and from 56.5° (± 20.8, range 30-90) to 6.1° (± 6.8, range 0-20) in the septic group (p < 0.001). The mean postoperative flexion was 105.2° (± 13.2, range 75-130) in the aseptic group and 102.7° (± 12.5, range 80-120) in the septic group (p = 0.32). Three failures (14% of the cases) occurred in the aseptic group and five in the septic group (38% of the cases). The overall survivorship at 10 years was 83.3% (22 cases, CI₉₅ 94.2-121.7) vs 58% (13 cases, CI₉₅ 67.2-111.7) in the aseptic and septic group, respectively (p = 0.01).

CONCLUSIONS

EMA reconstruction after extensor mechanism disruptions in TKA is a reliable salvage procedure. The septic nature of the revision decreased the functionality of the knee joint after EMA, but it did not represent a risk factor for re-ruptures or recurrence of infection.

LEVEL OF EVIDENCE

Level III.

Extensor Mechanism Reconstruction After Total Knee Arthroplasty with Allograft Versus Synthetic Mesh: A Multicenter Retrospective Cohort

INTRODUCTION

Patellar and quadriceps tendon ruptures after total knee arthroplasty (TKA) have historically poor outcomes. To date, there is no consensus for optimal treatment. The purpose of this study is to directly compare clinical outcomes and survivorship between allograft versus synthetic mesh for reconstruction of native extensor mechanism (EM) rupture after TKA.

METHODS

A multicenter, retrospective review identifying consecutive TKA patients operated between December 2009 to November 2019 was conducted. Patients aged ≥ 45 years old with native EM disruption treated with either allograft or synthetic mesh with minimum 2 year follow-up were included. Demographic information, injury mechanism, range of motion, surgical time, revision surgeries, and postoperative Knee Injury and Osteoarthritis Outcome Scores (KOOS Jr.) were collected. Student t-tests and Fisher exact tests were used to compare the demographic data between groups. The Kaplan-Meier survival curve method was used to determine the survivorship as treatment failure was defined as postoperative EM lag >30° or revision surgery. Survival curves were compared using the log-rank test. Univariate Cox proportional hazard regression identified risk factors associated with treatment failure.

RESULTS

Twenty patients underwent EM reconstruction using allograft versus 35 with synthetic mesh. Both groups had similar demographics and an average follow-up time of 3.5 years (P = 0.98). Patients treated with allograft had significantly greater postoperative flexion than patients treated with mesh (99.4 ± 9.5 allograft versus 92.6 ± 13.6 synthetic mesh, P = 0.04). Otherwise, there was no difference in postoperative outcomes between the two groups in average KOOS Jr. (P = 0.29), extensor lag (P = 0.15), graft failure (P = 0.71), revision surgery rates (P = 0.81), surgical time (P = 0.42), or ambulatory status (P = 0.34) at the most recent follow-up. Survival curve comparison also yielded no difference at up to 5-year follow-up (P = 0.48).

DISCUSSION AND CONCLUSION

Our findings suggest that reconstruction with allograft or synthetic mesh leads to similar clinical outcomes with good survivorship. Future studies, including larger randomized control trials, are required to determine the superior reconstruction method for this injury.

LEVEL OF EVIDENCE

III.

Extensor mechanism reconstruction with allograft following total knee arthroplasty: a systematic review and meta-analysis of achilles tendon versus extensor mechanism allografts for isolated chronic patellar tendon ruptures

BACKGROUND

Extensor mechanism rupture is a severe complication with an incidence of 0.1-2.5% after total knee arthroplasty (TKA). Achilles tendon allograft (ATA) and extensor mechanism allograft (EMA) in TKA surgery have yielded mixed clinical results. Our systematic review aims to identify the proportion of failure in extensor mechanism reconstruction after TKA using allograft and evaluate clinical and functional outcomes and the most common complications. Furthermore, we performed a meta-analysis among studies dealing with isolated patellar tendon ruptures to assess the failure rate, surgical complications, and clinical findings (extensor lag and knee range of motion) of extensor mechanism reconstruction using either ATA or EMA grafts.

METHODS

A systematic review of the literature was performed following the PRISMA guidelines, including the studies dealing with the use of EMA and ATA for extensor mechanism rupture following TKA. Coleman Methodology Score and the MINORS score were used to assess the quality of the studies. A meta-analysis was performed to evaluate the failure rate, complications, and clinical findings (extensor lag and knee range of motion) of the ATA and EMA treatments in isolated patellar tendon ruptures.

RESULTS

A total of 238 patients (245 knees), with a mean age ranging from 54 to 74 years, who underwent extensor mechanism reconstruction with an allograft were identified in the 18 included studies. We analysed 166 patellar tendon ruptures, 29 quadriceps tendon ruptures, and 29 patellar fractures in the analysis. A chronic injury was described in the majority of included cases. ATA and whole EMA were used in 89 patients (92 knees) and 149 patients (153 knees), respectively. The overall failure percentage was 23%, while EMA and ATA were 23 and 24%. The most common complication was extensor lag (≥ 20°). The overall incidence of postoperative infection was 7%. Eleven of 14 included papers reported more than 100° of the mean postoperative knee flexion. The percentage of patients requiring walking aids is 55 and 34.5% in ATA and EMA, respectively. The failure outcome after extensor mechanism reconstruction in isolated patellar tendon ruptures was 27%, with no statistical difference between EMA and ATA in terms of failure rate and clinical outcomes.

CONCLUSIONS

Extensor mechanism reconstruction with allograft represents a valid treatment option in patients with acute or chronic rupture following total knee arthroplasty. Persistent extensor lag represents the most common complication. EMA is associated with a lower frequency of patients requiring walking aids at last follow-up, although it has similar clinical and functional outcomes to ATA. In patellar tendon ruptures, ATA has a comparable success rate with EMA.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

TRIAL REGISTRATION

PROSPERO 2019 CRD42019141574.

Techniques for extensor mechanism reconstruction after total knee arthroplasty: Is there a clear winner?

Extensor mechanism (EM) disruption after total knee arthroplasty (TKA) is rare, but can result in devastating outcomes for patients including inability to ambulate. Disruption can occur at the quadriceps tendon, patella, or patellar tendon. This complication can be traumatic, but is often atraumatic from an iatrogenic or degenerative etiology. Primary repair for treatment of EM disruption has led to poor results with high failure rates and has mostly been abandoned. Most commonly accepted techniques center around Achilles tendon allograft reconstruction, synthetic mesh reconstruction, or other smaller options. However, to date, there is still no consensus for the optimal EM reconstructive technique due to the heterogeneity and small sample sizes of published studies. The need to identify a consistent and effective surgical technique is paramount to restore quality of life to patients who suffer from EM disruption after TKA. The purpose of this review is to describe the osteology, vasculature, and EM of the knee, identify risk factors associated with EM disruption after TKA, outline the considerations for surgical management, as well as compare and analyze the latest contributions to the literature, in particular allograft versus synthetic mesh, in the reconstruction of the EM after TKA.

A staged procedure for the treatment of chronic patellar tendon ruptures after total knee arthroplasty

The management of extensor mechanism lesions after total knee replacement is still associated with an unacceptably high complication rate, especially in its chronic setting. In this study, we report on 4 patients with chronic (> 3 months) patellar tendon rupture after knee arthroplasty, who were treated with a novel procedure of staged patella advancement prior to reconstruction with autografts. Initially, a unilateral frame was applied connecting the patella with the tibial shaft. The construct allowed for gradual distal advancement of the patella based on the Ilizarov principles. After achieving the desired patella height, the frame was removed, and the patellar tendon was reconstructed with hamstrings. All four patients experienced a significant improvement in extensor lag by a mean of 38.0°, while Knee society scores increased by a mean of 38.5 units. No substantial loss in active knee flexion was observed. Our findings suggest that our technique yields favorable outcomes in patients with patellar tendon disruption in the setting of a total knee arthroplasty.

Bilateral Extensor Mechanism Allograft Reconstruction in Native Knees: A Case Report

CASE

A 66-year-old man presented with chronic bilateral extensor mechanism dysfunction and profound patella baja after failed revision surgery for bilateral quadriceps tendon ruptures. Staged bilateral reconstruction with complete extensor mechanism allograft resulted in excellent two-year satisfaction and clinical outcomes.

CONCLUSION

Complete extensor mechanism reconstruction can be a successful treatment for chronic quadriceps tendon rupture with profound patella baja.

EXTENSOR MECHANISM TRANSPLANTATION AFTER KNEE PROSTHESIS: 70-MONTH FOLLOW-UP

Objective:

This article reports the range of motion, failure rate, and complications of patients with extensor mechanism injury after total knee arthroplasty (TKA) treated with extensor mechanism allograft with mid-term follow-up.

Methods:

Patients undergoing post-ATJ extensor mechanism transplantation from 2009 to 2018 were retrospectively evaluated. Demographics, the reason for transplantation, elapsed time from arthroplasty to transplantation, related surgical factors, immobilization time, range of motion, transplant failure, and complications were collected. The minimum follow-up was 24 months.

Results:

Twenty patients were evaluated. The mean follow-up was 70.8 +/- 33.6 months. The most common cause of extensor mechanism rupture was traumatic in 10 (50%) cases. Six patients underwent associated surgeries, one case of medial ligament complex reconstruction, and 5 cases of TKA revision. Eleven patients (55%) had transplant-related complications. The most common complication was an infection. Five cases presented transplant failure.

Conclusion:

Patients who underwent extensor mechanism allograft transplantation after total knee arthroplasty had a 25% failure rate with a mean follow-up of 6 years. Although there was no loss of flexion with the procedure and prolonged immobilization, the complication rate was not low. Level of evidence IV; case series .

Classification and Management of Periprosthetic Patella Fractures

Complications related to the extensor mechanism and patellofemoral joint continue to be the most common cause of pain and indication for surgical revision following total knee arthroplasty. Numerous risk factors related to the patient, implant, and technical performance of the procedure have been identified. The Ortiguera and Berry classification system is widely used for the systematic classification and management of these fractures. Because of the difficult nature of revision surgery for fracture and the high risk of complication, a careful assessment of the fracture and implants is vital to determining the best course of treatment.

Chronic Quadriceps Tendon Rupture Reconstruction with Sartorius Muscle Transfer: A Report of Five Cases

Disruption of the knee extensor mechanism is an unfavorable situation because efficient mobilization requires a functioning knee extensor apparatus. The purpose of this retrospective study was to report our technique of sartorius muscle transfer for restoration of extension mechanism function and the outcomes of five patients. Patients with ruptured knee extensor mechanism secondary to trauma or knee arthroplasty-related issues were studied retrospectively. In all patients, sartorius muscle was transferred to restore the quadriceps tension deficit. Increase in the knee active range of motion, increase in the extensor mechanism power by one grade on Medical Research Council scale, and improvement in the extension lag were observed in all patients. The sartorius muscle transfer can be a reliable option to restore the knee extensor mechanism in chronic quadriceps tendon injuries. Our initial results are promising and showed improvement of the extensor mechanism muscle power, increased knee active range of motion, and decreased knee extension lag. The complications we observed did not impair the successful outcome of the sartorius transfer and were anticipated given the complexity of the studied cases. We encourage additional studies of sartorius muscle transfer to treat chronic quadriceps tendon injuries.

Successful mid- to long-term outcome after reconstruction of the extensor apparatus using proximal tibia-patellar tendon composite allograft

PURPOSE

The purpose of the study was to assess the outcomes of extensor mechanism reconstruction with proximal tibia-patellar tendon composite allograft.

METHODS

24 consecutive patients treated with allograft-prosthetic composite for proximal tibia tumour resection and a conventional total knee arthroplasty were included. Extensor mechanism reconstruction was performed with a proximal tibia-patellar tendon composite allograft and the suture of the donor tendon to the remnant native patellar tendon. Function was evaluated by the Musculoskeletal Tumor Society score (MSTS) and range of motion. Western Ontario and MacMaster University (WOMAC) and visual analogue scale for pain also were used.

RESULTS

After a mean follow-up of 11.7 (range 3-15) years, mean MSTS score was 22.4 (range 20-30), mean flexion was 94.0° (range 84°-110°), and mean extension lag was 7.2° (range 0°-18°). The mean VAS-pain was 4.3 (range 2-6), and WOMAC score was 72.4 (range 58-100). There was no failure of the reconstructed extensor mechanism.

CONCLUSION

Patellar tendon reconstruction with allogeneic tissue from the proximal tibia allograft sutured to the recipient's remnant patellar tendon provides the mechanical support needed for healing of the reconstructed extensor mechanism with a substantial functional benefit to stabilize active knee extension and successful reconstruction survival at long-term.

LEVEL OF EVIDENCE

III.

Extensor mechanism failure in total knee arthroplasty

Extensor mechanism failure in total knee arthroplasty (TKA) can present as quadriceps tendon rupture, patella fracture or patella tendon rupture.Component malrotation, excessive joint line elevation and previous lateral release are some of the risk factors contributing to extensor mechanism failure in TKA.Partial quadriceps tendon rupture and undisplaced patella fracture with intact extensor mechanism function can be treated conservatively.Extensor mechanism failure in TKA with disruption of the extensor mechanism function should be treated operatively as it is associated with poor function and extensor lag.It is recommended that acute repair of patella or quadriceps tendon rupture are augmented due to the high risk of re-rupture.Chronic ruptures of the extensor mechanism must be reconstructed as repair has a high failure rate. Reconstruction can be performed using autograft, allograft or synthetic graft. Cite this article: EFORT Open Rev 2021;6:181-188. DOI: 10.1302/2058-5241.6.200119.

Meta-analysis Comparing Allograft to Synthetic Reconstruction for Extensor Mechanism Disruption after Total Knee Arthroplasty

Extensor mechanism disruption following total knee arthroplasty (TKA) is a devastating complication that causes high failure rates. There is controversy on what is the best way to do an extensor mechanism reconstruction. This study aims to compare both allograft and synthetic reconstructive techniques for success, reoperation, and infection rates and functional outcomes. The search on PubMed, MEDLINE, Embase, BIOSIS, and Cochrane databases was performed on March 15, 2019, using the following keyword groups: (1) "extensor mechanism" and "total knee arthroplasty," (2) "extensor mechanism" and "knee arthroplasty," (3) "extensor mechanism" and "revision total knee arthroplasty," and (4) "extensor mechanism" and "revision knee arthroplasty". Only studies on extensor mechanism disruption after TKA that included sufficient data to compare these two surgical techniques were included. Meta-analysis was performed with random effect model using the DerSimonian-Laird method. Thirty studies were included. The overall success rate of the reconstruction was 73.3% (95% confidence interval [CI]: 0. 651, 0.814). The success rate of allograft (72.8%, 95% CI: 0.626, 0.829) was not significantly different from synthetic material (78%, 95% CI: 0.707, 0.852, p = 0.416). There was no significant difference in revision rates between allograft (14.2%, 95% CI: 0.095, 0.189) and synthetic material (16%, 95% CI: 0.096, 0.223, p = 0.657). The overall relative risk of infection was 4.301 (95% CI: 1.885, 9.810). There was no significant difference in relative risk of infection between allograft (3.886, 95% CI: 1.269, 11.903) and synthetic material (4.851, 95% CI: 1.433, 16.419, p = 0.793). No statistically significant difference was found in mean postoperative Knee Society score (73.109 [95% CI: 67.296, 78.922] vs. 72.679 [95% CI: 69.184, 76.173], p = 0.901) between allograft and mesh reconstruction groups. There were no significant differences in overall failures, infections, functional outcomes, or revision reconstructions between allograft and synthetic material extensor mechanism reconstructions. Our results demonstrate the difficulty in treating this serious injury, independent of technique, as well as the significant risk for overall failure and infection.

Extensor Mechanism Reconstruction Using Allograft Following Total Knee Arthroplasty: A Review of Current Practice

The disruption of the extensor mechanism/apparatus of the knee is a dreaded complication following Total Knee Arthroplasty (TKA). Fresh frozen allograft containing the patella, and peripatellar musculotendinous attachments has emerged as an ideal alternative or salvageable option for the efficient reconstruction of extensor mechanism disrupted following TKA, where repair is almost impossible. However, any allograft implantation is associated with certain complications and extensor apparatus allograft is not the exception. Despite being allogenic, reconstruction of the extensor mechanism of the knee using allograft has given promising results. This narrative review aims to elaborate on the current application of allograft in the reconstruction of the disrupted extensor mechanism following TKA.

Modified Allograft Reconstruction of a Disrupted Patella Tendon: A Technical Case Report

CASE

A 19-year-old woman with a history of Hoffa fat pad syndrome underwent infrapatellar fat pad synovectomy and subsequently developed extensor mechanism disruption secondary to iatrogenic patellar tendon injury. She received a modified extensor mechanism patella-patellar tendon-tibial tubercle allograft to restore extensor function with satisfactory results at 2-year follow-up. We also review alternative techniques that were considered for her extensor mechanism repair.

CONCLUSION

The patient demonstrated satisfactory outcomes, similar to other established techniques. This modified extensor mechanism allograft reconstruction may be an effective alternative for patients experiencing acute extensor mechanism disruptions.

Extensor Mechanism Reconstruction Using Marlex Mesh: Is Postoperative Casting Mandatory?

BACKGROUND

Extensor mechanism (EM) disruption after total knee arthroplasty is a catastrophic complication. Reconstruction using monofilament polypropylene mesh (Marlex Mesh; CR Bard, Franklin Lakes, NJ) has emerged as the preferred treatment, but reports are limited to the designing institution. This study describes a nondesigner experience and compares 2 postoperative immobilization strategies: long leg cast vs knee immobilizer.

METHODS

A retrospective review of consecutive EM reconstructions between 2012 and 2019 was performed. Primary repairs and allograft reconstructions were excluded, leaving 33 knees (30 patients) who underwent Marlex reconstruction. Mean time from disruption to reconstruction was 14 months, and 14 of 33 (42%) had previous repair or reconstruction attempts. The mean age was 69 years, and mean body mass index was 35 kg/m². Postoperatively, extension was maintained using a knee immobilizer in 19 of 33 (58%) patients, whereas 14 of 33 (42%) patients were long leg casted. Kaplan-Meier analysis determined all-cause survivorship free of mesh failure.

RESULTS

At mean 25-month follow-up, 19 of 33 (58%) EM reconstructions were functioning. Excluding explanted infections (5 recurrent and 2 new), 19 of 26 (73%) EM reconstructions were in situ. Six-year survivorship was 69% and not influenced by immobilization type (cast: 67%, immobilizer: 71%; P = .74). Extensor lag was not associated with immobilization type, improving from a mean preoperative lag of 43° to a mean postoperative lag of 9°. Among successes, University of California at Los Angeles activity and Knee Injury and Osteoarthritis Outcome Score - Joint Replacement score improvements exceeded minimal clinically important difference (2.2-3.3 and 52.5-64.0, respectively).

CONCLUSION

Marlex mesh EM reconstruction is a durable and reliable treatment with acceptable clinical results achievable outside the designer institution. Provided sufficient duration and compliance with postoperative immobilization, similar outcomes can be obtained with either a cast immobilizer or a knee immobilizer.

Enhanced Biomechanical Performance of a Modern Polyester Surgical Mesh for Extensor Mechanism Reconstruction in Total Knee Arthroplasty

BACKGROUND

Extensor mechanism (EM) disruption following total knee arthroplasty is a devastating postoperative complication. Reconstruction with a synthetic mesh is one treatment option, although the optimal mesh material remains unknown. This study sought to compare the mechanical properties of 2 mesh material types that can be used for EM reconstruction.

METHODS

Mechanical properties of a polypropylene mesh (Marlex mesh) and Ligament Advanced Reinforcement System (LARS) mesh were compared using force-displacement data from a material testing machine simulating knee movement during normal human gait. Tension to failure/ultimate tensile load, stiffness coefficients, axial strain, and cyclic hysteresis testing were measured and calculated.

RESULTS

Compared to polypropylene mesh, LARS mesh demonstrated a significantly higher mean ultimate tensile load (2223 N vs 1245 N, P = .002) and stiffness coefficient (255 N/mm vs 14 N/mm, P = .035) in tension to failure testing, and significantly more energy dissipation (hysteresis) in hysteresis testing (771 kJ vs 23 kJ; P ≤ .040). LARS mesh also demonstrated significantly less maximum displacement compared to the polypropylene mesh (9.2 mm vs 90.4 mm; P ≤ .001).

CONCLUSION

Compared to polypropylene mesh, LARS mesh showed superior performance related to force-displacement testing. The enhanced mechanical performance of LARS mesh may correlate clinically to fewer failures, increased longevity, and higher resistance to plastic deformation (extensor lag). Future research should evaluate survivorship and clinical outcomes of these meshes when used for EM reconstruction.

Periprosthetic fractures about total knee arthroplasty

Periprosthetic fracture after total knee arthroplasty presents a difficult complication for many orthopaedic surgeons. These fractures occur most frequently around the distal femur followed by the patella and then tibia. These fractures are frequently complicated by poor bone quality or compromised bone due to the presence of the implants. Surgical treatment is typically necessary and requires varied techniques of open fixation, intramedullary fixation, or revision arthroplasty. Outcomes of these injuries vary widely. This review aims to describe the epidemiology, classification, treatment options and outcomes for periprosthetic fractures following total knee arthroplasty.

Synthetic Mesh Allograft Reconstruction for Extensor Mechanism Insufficiency After Knee Arthroplasty

Extensor mechanism (EM) insufficiency after knee arthroplasty is a rare but devastating complication resulting in severe disability. To date, primary repair and allograft reconstructive options have produced suboptimal results. A synthetic mesh allograft reconstruction technique has recently been introduced with promising outcomes. A retrospective chart review was performed to identify all patients who experienced EM failure after total or unicompartmental knee arthroplasty and subsequently underwent synthetic mesh EM reconstruction using a previously described technique. Patient demographics, pre- and postoperative knee range of motion and residual extensor lag, pre- and postoperative pain and functional outcome scores, and complications were extracted during the chart review. Twelve patients met inclusion criteria: 3 with patellar tendon and 9 with quadriceps tendon defects. At mean follow-up of 27.0 months, all patients were ambulatory, with a mean residual extensor lag of 12.9° (range, 0°-30°). Mean visual analog scale pain score decreased significantly after EM reconstruction: 4.6±2.3 (range, 1-8) preoperatively vs 1.8±2.4 (range, 0-7) postoperatively (P=.01). The mean Knee Society knee score improved from 41.5±11.1 (range, 21-57) preoperatively to 79.5±13.8 (range, 54-90) postoperatively (P<.0001). The mean Knee Society function score improved from 14.6±12.3 (range, 0-40) preoperatively to 64.2±27.1 (range, 5-95) postoperatively (P<.0001). One clinical failure occurred as a result of prosthetic joint infection. Synthetic mesh EM reconstruction effectively restores knee function for a variety of EM deficiencies following knee arthroplasty. [Orthopedics. 2019; 42(4):e385-e390.].

Synthetic Graft Compared With Allograft Reconstruction for Extensor Mechanism Disruption in Total Knee Arthroplasty: A Multicenter Cohort Study

BACKGROUND

Extensor mechanism disruption after total knee arthroplasty is a serious complication leading to notable patient morbidity. The purpose of this study is to compare the outcomes of extensor mechanism allograft with synthetic graft reconstruction.

METHODS

We retrospectively identified all patients who underwent extensor mechanism reconstruction using either allograft or synthetic graft from two high-volume academic arthroplasty institutions between 2006 and 2017. We collected extensor lag, need for ambulatory aids, and patient-reported outcome measures, as well as the incidence of postoperative complications and revision surgeries. We evaluated cost differences, considering both material cost and the need for revision surgery.

RESULTS

We identified 27 cases. A significantly greater postoperative extensor lag was found in the allograft group (P = 0.05). Graft failure after synthetic reconstruction was zero, with an overall revision surgery rate of 15%. Graft failure was 21%, and the revision surgery rate was 43% after allograft reconstruction. The allograft cost was significantly higher compared with the synthetic graft cost (P = 0.001). The mean total cost was 4,733.08 CAD for the synthetic group and 24,050.40 CAD for the allograft group (P = 0.17).

DISCUSSION

Synthetic reconstruction for extensor mechanism disruption shows benefit in postoperative extensor lag, graft failure, revision surgery, and cost when compared with allograft.

LEVEL OF EVIDENCE

Level III.

Treatment of Extensor Tendon Disruption After Total Knee Arthroplasty: A Systematic Review

BACKGROUND

Patellar or quadriceps tendon ruptures after total knee arthroplasty constitute a devastating complication with historically poor outcomes. With advances in soft tissue reconstruction and repair techniques, treatment has become more nuanced. Numerous graft options for reconstruction and suture techniques for repair have been described but there is no consensus regarding optimal treatment.

METHODS

A search of PubMed, MEDLINE, Embase, and Scopus was conducted. Articles meeting inclusion criteria were reviewed. Type of intervention performed, type of injury studied, outcome measures, and complications were recorded. Quantitative and qualitative analyses were performed.

RESULTS

Twenty-eight articles met inclusion criteria. The complication rate after repair of patellar tendon (63.16%) was higher than the complication rate after repair of quadriceps tendon (25.37%). However, the complication rate for patellar and quadriceps tendon tears after autograft, allograft, or mesh reconstruction was similar (18.8% vs 19.2%, respectively). The most common complication after extensor mechanism repair or reconstruction was extension lag of 30° or greater (45.33%). This was followed by re-rupture and infection (25.33% and 22.67%, respectively). Early ruptures had a higher overall complication rate than late injuries.

CONCLUSION

Extensor mechanism disruption after total knee arthroplasty is a complication with high morbidity. Reconstruction of patellar tendon rupture has a much lower complication rate than repair. Our findings support the recommendation of patellar tendon reconstruction in both the early and late presentation stages. Quadriceps rupture can be treated with repair in early ruptures or with reconstruction in the late rupture or in the case of revision surgery.

Retrieval analysis of a failed synthetic mesh extensor mechanism reconstruction after total knee arthroplasty

Extensor mechanism disruption after total knee arthroplasty is a relatively rare but potentially devastating complication. One technique to address this problem involves reconstruction with synthetic mesh. Although there are reports of successful clinical outcomes using this technique, we are not aware of any histological analyses of removed mesh grafts. This case report of a failed mesh reconstruction includes a retrieval analysis demonstrating robust host soft-tissue incorporation into the mesh graft and supports the rationale for continued use of this off-label technique. This case report also highlights the need for careful operative technique when performing these procedures to increase the chance of a successful outcome.

ALT flap with vascularized fascia lata for one-stage functional patellar tendon reconstruction

INTRODUCTION

Composite anterolateral thigh (ALT) flap with vascularized fascia lata can reconstitute patellar tendon integrity and knee soft tissue coverage in one stage. However, long-term evidence of outcomes is lacking. This work analyzes long-term functional results, compares subtotal and total reconstruction of patellar tendon, and assesses the respective function of the extensor apparatus.

PATIENTS AND METHODS

Outcomes of reconstruction using 10 ALT flaps in 9 patients (age range 21-87 years) were analyzed (mean follow-up 30 ± 6 months). Knee Society Scores, isometric knee extensor strength (M1-M5), and sensory recovery were evaluated, together with active range of motion and extensor lag of the reconstructed limb, compared to contralateral.

RESULTS

Ten flaps were used for tendon replacement in 9 patients. Eight (80%) free flaps and 2 (20%) propeller distally based flaps were used. Complications requiring the harvest of a second flap were seen in 2 patients. All patients could return to their daily activities without the use of walking supports. Mean active ROM was 94.4° with an extensor lag of 9.4°, without a significant difference between partial and total patellar tendon reconstruction. The mean knee and functional scores of the Knee Society were 81/100 and 77/100, respectively.

CONCLUSION

Composite ALT flap with fascia lata can satisfy the twofold needs of functional restoration and soft tissue coverage, thus ensuring stable results in total and subtotal knee extensor mechanism reconstruction. Distally based flaps should be carefully considered, as they lead to higher complication rates.

Partial extensor mechanism allograft reconstruction for chronic patellar tendon disruption shows superior outcomes in native knees when compared to same technique following total arthroplasty

PURPOSE

Chronic patellar tendon disruption occurs mostly after total knee arthroplasty, and is a challenging complication to treat. We have previously described an original technique for reconstruction using extensor mechanism allograft. The goal of this study was to assess the results of this technique in TKA and native knees.

METHODS

An observational, single centre, retrospective study was conducted. Nine patients in the TKA group and eight in the native knee group were included, all treated for chronic PT rupture. The operative technique included fresh-frozen allograft, in which the patella was fashioned into an hourglass shape and press-fit in a corresponding groove in the native patella. The primary outcome was failure of the graft defined by a residual extensor lag > 10°.

RESULTS

The mean age was 68 in the TKA group and 51 in the native group. The minimum follow-up was 24 months and the mean follow-up respectively 42 and 39 months. 33% of allografts failed in the TKA group where none failed in the native knee group, with a mean extension lag of 12.2° (0-30) and 1.25° (0-5), respectively. All but the three failures presented with an extension lag < 10°. Four cases of patellar bone block distal migration, less than 1 cm, were recorded in the native knee group without clinical repercussion.

CONCLUSIONS

The results of this original technique in the setting of chronic PT rupture were excellent for native knees at a minimum follow-up of 24 months. However, results were less satisfactory in the TKA group, due to the substantial rate of failure. LEVEL OF EVIDENCE III.

Extensor Mechanism Reconstruction with Use of Marlex Mesh: A Series Study of 77 Total Knee Arthroplasties

BACKGROUND

Disruption of the extensor mechanism after total knee arthroplasty (TKA) is debilitating, and the reported results of numerous reconstructive options have varied. We previously reported the early results of 13 patients who underwent reconstruction of the extensor mechanism with use of Marlex mesh. The purpose of the current study was to assess results in a larger cohort of patients, with an emphasis on the survivorship of the mesh, clinical results, and complications.

METHODS

During the period of 2000 to 2015 at a single tertiary care academic institution, 77 patients (77 TKAs) underwent reconstruction with use of Marlex mesh for an extensor mechanism disruption (27 quadriceps tendon disruptions, 40 patellar tendon disruptions, and 10 patellar fractures). The mean patient age at the time of reconstruction was 65 years; 70% of the patients were female. The mean body mass index was 35 kg/m. The mean follow-up was 4 years. Eighteen (23%) of the patients underwent mesh reconstruction with the primary TKA in place, and 59 (77%) had mesh reconstruction at the time of revision TKA. The mean time between disruption and reconstruction was 7 months. Twenty (26%) of the patients had previously undergone attempted extensor mechanism reconstruction at outside institutions.

RESULTS

Sixty-five of the 77 mesh reconstructions were in place at the time of the latest follow-up. Twelve patients experienced a failure that required mesh revision: 5 for patellar tendon rupture, 5 for quadriceps tendon rupture, and 2 for symptomatic lengthening. Four additional patients with mesh failure were treated nonoperatively with bracing. The 2-year survivorship free of mesh revision was 86% for patients with no prior reconstruction and 95% for patients with previous reconstructions of the extensor mechanism that did not involve Marlex mesh. Knee Society Score (KSS) results significantly improved following reconstruction (p < 0.001). Extensor lag improved by a mean of 26°, with mean postoperative extensor lag measuring 9° (p < 0.001).

CONCLUSIONS

Reconstruction of the extensor mechanism with use of Marlex mesh is a viable option in patients with catastrophic disruption after TKA. At the time of the latest follow-up, 84% of the mesh reconstructions were in place and the functional outcomes were excellent, with mean improvement in extensor lag of 26°. Extended follow-up is required, but the results of this large series with a mean follow-up of 4 years are encouraging.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Synthetic mesh vs. allograft extensor mechanism reconstruction in total knee arthroplasty - A systematic review of the literature and meta-analysis

BACKGROUND

Extensor mechanism disruption after total knee arthroplasty (TKA) is a devastating complication. Reconstruction with allograft and synthetic mesh has been described. However, these reports have typically been small case series, and controversy exists with regard to which reconstruction technique is optimal.

METHODS

The authors performed a systematic review using PUBMED, MEDLINE, EMBASE, BIOSIS, Clinicaltrials.gov, and Cochrane Database of Systematic Reviews identifying 14 articles meeting inclusion criteria and producing 204 knees for comparison. Studies with repairs performed under full knee extension were included. Case reports and non-English studies were excluded. Available demographics and clinical outcome data were collected from each study. Appropriate statistical analysis was performed to compare the variables.

RESULTS

Baseline demographics and patient complexity were similar between the two cohorts. Reconstruction success rates (76% allograft vs. 74% mesh), average time to diagnosis/treatment, Knee Society Scores (KSS), knee range of motion/extensor lag, and complication rates yielded no statistical difference. Synthetic mesh was used more frequently with concomitant revision of components.

DISCUSSION

This systematic review shows equivalent success of allograft and synthetic mesh with approximately 25% failure rate in both groups. Periprosthetic joint infection remains a common and significant complication and reason for failure in both groups. Overall, synthetic mesh showed equivalent extensor mechanism reconstruction success as allograft but with much lower cost, near universal availability, lack of disease transmission, and potential for diminishing graft stretch-out. Future research in larger case series or comparative study is needed to help aid in management of this largely unsolved problem in total knee reconstruction.

Reconstructing the chronically disrupted knee extensor mechanism after total knee arthroplasty: Hourglass variant of the original partial allograft technique

Allograft reconstruction is a valuable treatment option for patients with chronic extensor mechanism disruption after total knee arthroplasty. Here, an hourglass variant of the original partial allograft technique is described. An hourglass-shaped patellar bone block is press-fit into the native patella. The graft is fixed to both the patella and the tibia then sutured with the knee fully extended. Outcomes of this technique were assessed in 5 patients after at least 24months' follow-up. The mean knee and function Knee Society Score values were 77.8 and 64.0, respectively. Extension lag was less than 10 in all 5 patients. This hourglass variant of the partial allograft technique is a useful treatment option that can be used even after patellar resurfacing.

The Management of Extensor Mechanism Disruption After Total Knee Arthroplasty: A Systematic Review

We performed a literature search on PubMed, Web of Science, Science Direct/Scopus, Google Scholar, and Google to evaluate results of several techniques to manage disruption of the extensor mechanism after total knee arthroplasty. Different methods to manage extensor mechanism disruption are available at present, with no level I studies informing surgeons in an evidence-based fashion. Primary repair is not indicated. Allograft reconstruction could be effective, providing that appropriate surgical technique and allograft tensioning are implemented.

External fixator immobilization after extensor mechanism reconstruction in total knee arthroplasty

Extensor mechanism disruption after total knee arthroplasty is a complicated problem that typically requires surgical reconstruction. After extensor mechanism failure, reconstruction is typically indicated to restore active knee extension and provide a stable limb for ambulation. Immobilization of the knee in extension is vital in the initial postoperative period after extensor mechanism reconstruction. We describe a series of 4 patients who underwent extensor mechanism reconstruction followed by external fixator application to maintain the knee extended in the initial postoperative period. Our results have been favorable. However, close follow-up is important to monitor for the development of pin site infections.

Eradication rates, risk factors, and implant selection in two-stage revision knee arthroplasty: a mid-term follow-up study

Background

Two-stage revision (TSR) knee arthroplasty is an established treatment, but failure to control infection still occurs in 4–50 % of cases. The aim of this study was to assess the infection eradication rate, risk factors for failure, and the clinical outcome after two-stage revision knee arthroplasty.

Methods

This retrospective study included 59 patients who had undergone at least one two-stage revision procedure due to periprosthetic joint infection (PJI). Demographic data, comorbidities, types of implant, and complications were analyzed. Univariate and multivariate logistic regression analysis were used to identify risk factors for failure.

Results

The infections were controlled in 55 patients (93.2 %). The follow-up period was 4.1 (±2.7) years. Infection control was achieved after the first TSR in 42 patients (71.2 %) and after the second TSR in 13 (76.5 %). The percentage of arthrodesis procedures in patients with infection control increased from 16.75 % after one TSR to 69.2 % after two TSRs. Multivariate logistic regression analysis identified body mass index (BMI) (odds ratio 1.22; 95 % confidence intervals, 1.07 to 1.40; p = 0.004) and smoking (OR 21.52; 95 % CI, 2.60 to 178.19; p = 0.004) as risk factors for failure.

Conclusions

Two-stage revision protocols can achieve acceptable results even after a second procedure. It is still unclear whether the choice of implant influences failure rates. Risk factors for failure after two-stage revision were identified. Studies with larger sample sizes are needed in order to support these findings and identify further risk factors. To reduce failure rates, programs should be established to treat or minimize risk factors in patients with PJI.