Extensor Mechanism Allograft Research Articles

Extensor Mechanism Allografting

Extensor mechanism disruption is one of the most devastating complications after total knee arthroplasty that may result in considerable functional loss, even after attempted reconstruction. Early diagnosis and prompt treatment with extensor mechanism allograft may optimize outcomes. This article reviews the etiology and diagnosis of extensor mechanism disruption, but most importantly reviews the details of surgical reconstruction using fresh frozen extensor mechanism allograft. The sobering reality is that despite meticulous techniques and adherence to established principles, functional limitations may persist in as many as one-third of cases.

Extensor Mechanism Reconstruction: A Novel Technique for Bone Patella Allograft Post Partial Patellectomy Failure

Extensor mechanism disruption, whether due to patella fracture or tendon rupture, generally occurs after low-energy trauma and frequently involves an indirect mechanism. When the fracture is comminuted and reconstruction is impossible, a partial or total patellectomy may be indicated. Although some authors advocate total patellectomy, partial patellectomy remains the standard treatment, especially for young and active patients. In the rare instance of a failed tendon repair after partial or total patellectomy, inadequate tissue is usually available for adequate restoration of the extensor mechanism. Extensor mechanism allograft, using the tibial tuberosity, patellar tendon, patella, and quadriceps tendon in continuity or the Achilles' tendon with calcaneal bone-block in continuity has been reported for extensor mechanism repair after total knee arthroplasty in patients who did not undergo patellectomy. We present a novel technique, using the bone patellar tendon bone allograft to reconstruct a posttraumatic defect of the extensor mechanism in a 28-year-old, active patient with a failed partial patellectomy following fracture of his patella. Union of the allograft was seen on x-ray after 4 months. After 6 months, the patient reached full range of motion and returned to his previous sporting activities.

Treatment of chronic disruption of the patellar tendon in Osteogenesis Imperfecta with allograft reconstruction

We present a case of chronic disruption of the patellar tendon in a patient with Osteogenesis Imperfecta. This patient was treated with a customized extensor mechanism allograft. Results were excellent at 5 years follow up. To our knowledge this treatment has not previously been published in this situation. We present this as a reliable treatment option.

Extensor Mechanism Allograft for the Treatment of Extensor Mechanism Disruption After Total Knee Arthroplasty

Extensor mechanism failure after a total knee arthroplasty can be a devastating complication that is difficult to manage. Although primary repair of the extensor mechanism may be attempted acutely, similar management of a chronic disruption is associated with a substantial rate of failure and associated complications. Several options for secondary reconstruction exist, but a full extensor mechanism allograft that is tightly tensioned in full extension followed by immobilization for 6 weeks has been associated with the most consistent results. With this technique, the extensor allograft can be completely covered with host tissue, facilitating healing and restoration of active knee extension. The reconstruction requires attention to secure distal fixation and maximal extensor tension to achieve optimal outcomes.

Discussing Treatment Options

A sixty-year-old man presented to an orthopaedic surgeon with a periprosthetic infection after total knee arthroplasty performed by another surgeon. He underwent removal of the components, placement of an antibiotic spacer, and antibiotic suppression therapy. Eight weeks later, a revision total knee arthroplasty was performed. The patient did well initially but returned four months after the revision with periprosthetic reinfection. The revision components were removed, another antibiotic spacer was placed, and antibiotic suppression therapy was again administered. During the operation, the entire extensor mechanism, including the quadriceps tendon, patella, and patellar tendon, was found to be necrotic and required radical débridement. Five months later, another operation was performed to remove the spacer, and a plastic surgeon was consulted to assist in the wound closure because of the presence of extensive scar tissue. Intraoperative cultures were negative during these two most recent procedures. The orthopaedic surgeon presented the patient with four treatment options: arthrodesis, resection arthroplasty, amputation, or revision total knee arthroplasty with extensor mechanism allograft and a possible flap closure (rotational or free flap). The patient refused a knee arthrodesis and voiced a strong preference for amputation over arthrodesis. The patient's first choice, however, was to save the knee and to have a second radical revision performed. The surgeon then discussed in detail the risks that would be involved with reconstruction, including the high risk of reinfection and other wound complications. An infection, he explained, could lead to amputation, sepsis, and death. The surgeon also informed the patient that the procedure was not commonly performed, had no proven success rate, and could be fraught with complications. The patient remained steadfast in his choice and elected to undergo radical reconstruction of the knee.

Extensor Mechanism Allograft Reconstruction After Total Knee Arthroplasty

Disruption of the extensor mechanism is an infrequent but catastrophic complication after total knee arthroplasty. Treatment is technically challenging. For patellar tendon ruptures, multiple treatment options having been described with inconsistent results. Allograft tissue may provide the best means to adequately reconstruct the disrupted patellar tendon. Options for allograft reconstruction include an Achilles tendon bone block allograft or a whole extensor mechanism allograft. Important surgical principals include rigid fixation of the host allograft junction, coverage of the allograft tissue with as much autogenous tissue as possible to reduce the risk of infection, tensioning the graft in full extension, and not testing the completed repair is crucial. Current results with proper surgical technique show acceptable functional outcome for this devastating complication.

Die Behandlung der Streckapparatinsuffizienz nach Knieprothetik durch allogene Transplantation

We present three cases in which we used a complete extensor mechanism allograft for the reconstruction of an insufficient extensor mechanism after total knee arthroplasty (and failed reconstruction with local tissue in two of these cases). Early results are encouraging. Allograft reconstruction can be taken into consideration as an alternative to arthrodesis in those "worst-case scenarios". Late failure may occur in about 20%, probably due to a lack of revitalisation in the centre of the allograft.

Extensor Mechanism Allograft Reconstruction in TKA at a Mean of 56 Months

Extensor mechanism disruption in total knee arthroplasty (TKA) occurs infrequently but often requires surgical intervention. We compared two cohorts undergoing extensor mechanism allograft reconstruction and presumed both types of extensor mechanism allograft reconstruction will be successful but for different indications and forms of extensor failure. Nineteen consecutive patients with extensor mechanism disruption after TKA were treated. Two different types of extensor mechanism allografts were used: quadriceps tendon-patella-patella tendon-tibial tubercle, and Achilles tendon allograft. Demographic factors, diagnosis at extensor failure, Knee Society clinical rating scores, radiographs, and patient satisfaction were recorded. The average time from extensor mechanism disruption to surgery was 6.6 months (range, 1-24 months). At a mean followup of 56 months (range, 24-96 months), all patients were community ambulators. The mean Knee Society score improved from 27 points preoperatively to 76 points postoperatively. There was no loss of knee flexion postoperatively. The mean postoperative lag was 14 degrees. Fifteen patients had an extensor lag of less than 10 degrees. All patients thought their functional status had improved, and 89% were satisfied with the results of the allograft reconstruction. The total extensor mechanism allograft and Achilles tendon allograft both were successful in the treatment of the failed extensor mechanism.

Extensor Mechanism Allograft Reconstruction After Total Knee Arthroplasty

Disruption of the extensor mechanism is an uncommon but catastrophic complication of total knee arthroplasty. We evaluated two techniques of reconstructing a disrupted extensor mechanism with the use of an extensor mechanism allograft in revision total knee arthroplasty. Twenty consecutive reconstructions with the use of an extensor mechanism allograft consisting of the tibial tubercle, patellar tendon, patella, and quadriceps tendon were performed. The first seven reconstructions (Group I) were done with the allograft minimally tensioned. The thirteen subsequent procedures (Group II) were performed with the allograft tightly tensioned in full extension. All surviving allografts were evaluated clinically and radiographically after a minimum duration of follow-up of twenty-four months. All of the reconstructions in Group I were clinical failures, with an average postoperative extensor lag of 59 degrees (range, 40 degrees to 80 degrees ) and an average postoperative Hospital for Special Surgery knee score of 52 points. All thirteen reconstructions in Group II were clinical successes, with an average postoperative extensor lag of 4.3 degrees (range, 0 degrees to 15 degrees ) (p < 0.0001) and an average Hospital for Special Surgery score of 88 points. Postoperative flexion did not differ significantly between Group I (average, 108 degrees ) and Group II (average, 104 degrees ) (p = 0.549). The results of reconstruction with an extensor mechanism allograft after total knee arthroplasty depend on the initial tensioning of the allograft. Loosely tensioned allografts result in a persistent extension lag and clinical failure. Allografts that are tightly tensioned in full extension can restore active knee extension and result in clinical success. On the basis of the number of knees that we studied, there was no significant loss of flexion. Use of an extensor mechanism graft for the treatment of a failure of the extensor mechanism will be successful only if the graft is initially tensioned tightly in full extension.

EXTENSOR MECHANISM ALLOGRAFT RECONSTRUCTION AFTER TOTAL KNEE ARTHROPLASTY

Disruption of the extensor mechanism is an uncommon but catastrophic complication of total knee arthroplasty. We evaluated two techniques of reconstructing a disrupted extensor mechanism with use of an extensor mechanism allograft following total knee arthroplasty. Twenty consecutive reconstructions with use of an extensor mechanism allograft consisting of the tibial tubercle, patellar tendon, patella, and quadriceps tendon were performed. The first seven reconstructions (Group I) were done with the allograft minimally tensioned. The thirteen subsequent procedures (Group II) were performed with the allograft tightly tensioned in full extension. All surviving allografts were evaluated clinically and radiographically after a minimum duration of follow-up of twenty-four months. All of the reconstructions in Group I were clinical failures, with an average postoperative extensor lag of 59 degrees (range, 40 degrees to 80 degrees ) and an average postoperative Hospital for Special Surgery knee score of 52 points. All thirteen reconstructions in Group II were clinical successes, with an average postoperative extensor lag of 4.3 degrees (range, 0 degrees to 15 degrees ) (p < 0.0001) and an average Hospital for Special Surgery score of 88 points. Postoperative flexion did not differ significantly between Group I (average, 108 degrees ) and Group II (average, 104 degrees ) (p = 0.549). The results of reconstruction with an extensor mechanism allograft after total knee arthroplasty depend on the initial tensioning of the allograft. Loosely tensioned allografts result in a persistent extension lag and clinical failure. Allografts that are tightly tensioned in full extension can restore active knee extension and result in clinical success. On the basis of the number of knees that we studied, there was no significant loss of flexion. Use of an extensor mechanism graft for the treatment of a failure of the extensor mechanism will be successful only if the graft is initially tensioned tightly in full extension. Therapeutic study, Level III-2 (retrospective cohort study). See Instructions to Authors for a complete description of levels of evidence.

Extended Medial Gastrocnemius Rotational Flap for Treatment of Chronic Knee Extensor Mechanism Deficiency in Patients with and without Total Knee Arthroplasty

Nine patients with chronic extensor mechanism disruption were treated with an extended medial gastrocnemius rotational flap reconstruction of the extensor mechanism. Seven patients previously had total knee arthroplasty and two patients had chronic infection of nonreplaced, native knees. Four patients previously had failed Achilles' tendon allograft reconstruction after total knee arthroplasty and two were complicated by infection. Infected arthroplasty patients had a staged procedure with placement of an antibiotic spacer after debridement and extended medial gastrocnemius rotational flap, followed by total knee arthroplasty replant 8 weeks later. The four infected arthroplasty patients had medical comorbidities that included a patient with HIV and hemophilia, and two with diabetes mellitus. Another patient with rheumatoid arthritis was severely malnourished as a result of dumping syndrome. Of the four patients treated by this two-stage procedure, one died in the early postoperative period from chronic medical issues after the second stage and another patient elected to have above-knee amputation after the first stage because of severe reflex sympathetic dystrophy. The final group of seven patients was studied at a mean followup of 21 months (range, 7-31 months), the average extensor lag was 13.5 degrees (range, 0-50 degrees ), and the average range of motion was 2 degrees to 93 degrees . The two patients with nonreplaced, native knees had extensor lags of 30 degrees and 10 degrees . All patients were able to regain sufficient extensor mechanism strength to return to independent ambulation, and all infections resolved after treatment. Two patients were able to ascend stairs foot over foot without support. In addition to the patient who had amputation, the other complication involved a wound breakdown that required a free flap at 13 months in a patient who had a failed Achilles' tendon allograft reconstruction after takedown of a knee fusion. Medial gastrocnemius flap reconstruction can provide successful salvage of a failed extensor mechanism allograft or an alternative to allograft reconstruction in patients with poor soft tissue coverage, previous infection, or a compromised immune system.

Clostridium infection in a knee extensor mechanism allograft: case report and review

An unusual case of Clostridium perfringens infection after an allograft reconstruction of an extensor mechanism in a multiply revised total knee arthroplasty is reported. The case occurred in an elderly patient with an underlying bleeding dyscrasia who had previously undergone two revision total knee arthroplasties. The patient was treated by open irrigation, debridement, removal of allograft and prosthesis, intravenous antibiotics, and implantation of an antibiotic impregnated cement spacer utilizing an intramedullary rod.

High rate of failure of allograft reconstruction of the extensor mechanism after total knee arthroplasty.

Disruption of the extensor mechanism is an uncommon but devastating complication of total knee arthroplasty. Several techniques for reconstruction of the extensor mechanism after total knee arthroplasty have been reported, but we do not know of any study in which the results of one group's method were corroborated by a second group using the same technique. In the present series, we evaluated the results of reconstruction of the extensor mechanism with use of allograft according to the method described by Emerson et al. Seven reconstructions of the extensor mechanism with use of a bone-tendon-bone allograft were performed with the technique of Emerson et al. in six patients. The patients were evaluated before and after the operation. The knee score according to the system of The Hospital for Special Surgery, evidence of an extensor lag, use of walking aids, and the ambulatory status of each patient were recorded. The patients were also asked about, and the medical records were reviewed for, episodes of falling related to weakness of the quadriceps after the reconstruction. The mean duration of follow-up was thirty-nine months (range, six to 115 months). As these reconstructions often fail early, the minimum duration of follow-up was six months. All seven reconstructions were rated as clinical failures on the basis of a persistent or recurrent extensor lag of more than 30 degrees. All but one patient needed an assistive device full time for walking, and four patients (five knees) had at least one documented episode of falling that was due to giving-way of the affected knee. Four of the reconstructions were revised; one revision was performed with use of another extensor mechanism allograft and three were performed with use of a medial gastrocnemius rotation flap. The other three clinical failures had not been revised at the time of writing. At the time of the most recent follow-up (or at the time of revision of the extensor reconstruction), the mean extensor lag was 59 degrees and the mean knee score was 52 points (a poor result). Undertensioning of the allograft reconstruction at the time of the operation and attenuation of the allograft both may have played a role in the inability of the patients to regain active extension of the knee postoperatively. Alternative techniques for reconstruction of the extensor mechanism or modifications of this technique should be considered in the treatment of this difficult problem.

Extensor Mechanism Allografts in Total Knee Arthroplasty

Forty knees in 40 patients who had a chronic extensor mechanism disruption after knee arthroplasty underwent extensor mechanism allograft placement to restore extensor function. Thirteen knees were infected previously and 11 knees did not respond to previous attempts at direct extensor repair or reconstruction. Two patients died and two patients underwent above the knee amputation because of recurrent infection. The final group of 36 patients was studied for a mean followup of 3.6 years (range, 2-10 years). Clinical evaluations were performed using a modified Knee Society scoring system. The average range of motion in the entire group of patients was 1.4 degrees extension to 98 degrees flexion. The average extensor lag was 13 degrees in 15 of 36 patients. There were eight extensor allograft ruptures, which were treated by repeat extensor allograft placement. The average knee scores for function improved from 37 points preoperatively to 68 points postoperatively. Despite these initial ruptures, 34 of 36 patients had a successful clinical result. These results support the use of this technique for complete extensor mechanism loss after knee arthroplasty when direct repair is unfavorable.

Extensor Mechanism Reconstruction With an Allograft After Total Knee Arthroplasty

The authors report on a series of 15 knees in which an extensor mechanism allograft was used to treat a rupture of the patellar tendon associated with a total knee arthroplasty. Nine of the knees have greater than two-year follow-up evaluation (average, 4.1 years; range, 2.3-7 years). Postoperatively, the average flexion was 106 degrees. All but three patients achieved full passive extension. Six of the nine knees had no extensor lag. The average post-operative clinical score for the follow-up group was 78 points. Graft complications include one early graft rupture, one early quadriceps junction failure, and one patellar component loosening. One graft fractured after revision of a metal-backed patella.