Extensor Mechanism Deficiency Research Articles

Current failure mechanisms after knee arthroplasty have changed: polyethylene wear is less common in revision surgery.

The present study was designed to clarify which underlying indications can be currently considered the main reasons for failure after total knee arthroplasty as a function of time. We conducted a retrospective study that included all first revisions of total knee replacements during 2005 to 2010 at two high-volume arthroplasty centers. A revision was defined as the replacement of at least one prosthetic component. In the descriptive analysis, polyethylene wear, aseptic loosening, periprosthetic infection, malalignment, instability, arthrofibrosis, extensor mechanism deficiency, periprosthetic fracture, and retropatellar arthritis were given as the failure mechanism associated with an early, intermediate, or late time interval (less than one year, one to three years, and more than three years, respectively) after the index total knee arthroplasty. Three hundred and fifty-eight revision total knee arthroplasties were included. Of those revisions, 19.8% were performed within the first year after the index arthroplasty. The most common indications for revision, besides aseptic loosening (21.8%), were instability (21.8%), malalignment (20.7%), and periprosthetic infection (14.5%). Revisions due to polyethylene wear (7%) rarely occurred. In the early failure group, the primary causes of revision were periprosthetic infection (26.8%) and instability (23.9%). In the intermediate group, instability (23.3%) and malalignment (29.4%) required revision surgery, whereas late failure mechanisms were aseptic loosening (34.7%), instability (18.5%), and polyethylene wear (18.5%). Aseptic loosening, instability, malalignment, and periprosthetic infection continue to be the primary failure mechanisms leading to revision surgery. Contrary to previous literature, the results in the present study showed a substantial reduction in implant-associated revisions such as those due to polyethylene wear. Failure mechanisms that occur persistently early and in the intermediate term, such as periprosthetic infection, instability, and malalignment, remain common causes of revision surgery. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Why Are Total Knee Arthroplasties Failing Today—Has Anything Changed After 10 Years?

The purpose of this study was to determine the frequency and cause of failure after total knee arthroplasty and compare the results with those reported by our similar investigation conducted 10years ago. A total of 781 revision TKAs performed at our institution over the past 10years were identified. The most common failure mechanisms were: loosening (39.9%), infection (27.4%), instability (7.5%), periprosthetic fracture (4.7%), and arthrofibrosis (4.5%). Infection was the most common failure mechanism for early revision (<2years from primary) and aseptic loosening was the most common reason for late revision. Polyethylene (PE) wear was no longer the major cause of failure. Compared to our previous report, the percentage of revisions performed for polyethylene wear, instability, arthrofibrosis, malalignment and extensor mechanism deficiency has decreased.

One‐stage Versus Two‐stage Exchange

Liaison: Paul Lichstein MD, MSLeaders: Thorsten Gehrke MD (International), Adolph Lombardi MD, FACS (US), Carlo RomanoMD (International), Ian Stockley MB, ChB, MD, FRCS (International)Delegates: George Babis MD, Jerzy Bialecki MD, La´szlo´ Bucsi MD, Xu Cai MD, Li Cao MD, Briande Beaubien MD, Johannes Erhardt MD, Stuart Goodman MD, PhD, FRCSC, FACS, FBSE,William Jiranek MD, Peter Keogh, David Lewallen MD, MS, Paul Manner MD, WojciechMarczynski MD, J. Bohannon Mason MD, Kevin Mulhall MB, MCh, FRCSI, Wayne PaproskyMD, Preetesh Patel MD, Francisco Piccaluga MD, Gregory Polkowski MD, Luis Pulido MD, IanStockley MBBS, ChB, FRCS, Juan Suarez MD, Fritz Thorey MD, Rashid Tikhilov MD, JobDiego Velazquez MD, Heinz Winkler MD

Complications of Patellar Fracture Repair: Treatment and Results

Open reduction and internal fixation (ORIF) of patellar fractures generally leads to good results; however, the potential for surgical complications exists. Nonunion, infection, posttraumatic arthritis, arthrofibrosis, symptomatic hardware, and extensor mechanism insufficiency have all been described following patellar ORIF, and the risk of their occurrence may be augmented by patient-, injury-, and treatment-related factors. When complications arise, advanced reconstructive techniques are often required for successful management. This review will report the incidence of the aforementioned complications, highlight risk factors contributing to their frequency, discuss treatment options, and present the reported results of selected treatment strategies from available literature.

Causes of Instability After Total Knee Arthroplasty

The purpose of the present study was to characterize the underlying causes that lead to instability after total knee arthroplasty (TKA). We reviewed 83 revision TKAs (79 patients) performed for instability. After detailed analysis of patient's history, physical examination, operative report and radiographs, we identified six categories: flexion/extension gap mismatch, component malposition, isolated ligament insufficiency, extensor mechanism insufficiency, component loosening, and global instability. Twenty-five knees presented with multi-factorial instability. When these knees were classified according to the most fundamental category, each category above included 24, 12, 11, 10, 10 and 16 knees respectively. The unstable TKA may result from a variety of distinct etiologies which must be identified and treated at the time of revision. The revision TKA could be tailored to the specific causes.

Case Report: Failure of Rotating-hinge Total Knee Prosthesis by Disengagement of the Hinge-post Extension

Although modern-generation rotating-hinge knee implants have been modified to mitigate earlier complications related to aseptic loosening with these devices in revision TKAs, there are few, if any, reports of failure related to the hinge mechanism in these prostheses. We present a case of disengagement of the hinge-post extension in a contemporary rotating-hinge knee prosthesis originally implanted during revision surgery for instability and extensor mechanism insufficiency. We hypothesize the screw home kinematics of the knee resulted in a counterclockwise torque, contributing to the hinge post locking screw disengagement in this case. Although some authors have reported complications and failures related to aseptic loosening with rotating-hinge knee prostheses, there have been no reports regarding complications related to the hinge mechanism, which simultaneously links and permits rotation between the femoral and tibial components. Arthroplasty surgeons who use rotating-hinge knee prostheses need to be aware of this potential mode of failure. Design modifications, including more secure locking mechanisms and side-specific implants, may avoid this complication.

Surgical Technique: Vastus Medialis and Vastus Lateralis as Flap Transfer for Knee Extensor Mechanism Deficiency

Loss of the quadriceps tendon, patella, and patellar tendon leaves a major anterior defect that is difficult to close and compromises knee extension strength. Gastrocnemius muscle transfer does not sufficiently cover such major defects. This paper describes a new surgical technique that addresses these defects and the results of eight cases of revision TKA managed with this new technique. The new procedure transfers the vastus medialis or the vastus lateralis and their tibial attachments or both muscles and their distal expansions combined with gastrocnemius and soleus flaps to cover major deficiencies in the anterior knee. Nine cadaver knee specimens were dissected to determine the effect of the transfer on nerve and blood supply of the muscles. Eight patients underwent the new procedure between 2005 and 2009. Four knees had vastus medialis transfer, two vastus medialis and vastus lateralis transfer, two vastus medialis and medial gastrocnemius transfer, and two medial gastrocnemius and medial ½ of the soleus muscle transfer. Minimum followup was 15 months (mean, 43 months; range, 15-74 months). Patients were evaluated for anterior knee pain, quality of knee closure, ROM, extensor lag, walking ability, use of assistive devices, and ability to climb stairs with the operated extremity. All patients achieved closure of the knee without synovial leaks by 10 days postoperatively. Mean flexion contracture at last followup was 3° (range, 0°-7°). Mean extension lag was 22° (range, 5°-65°). Extension lag was less in those knees that included gastrocnemius or soleus muscle transfer. None of the flaps developed necrosis. The vastus medialis and vastus lateralis muscles provide adequate coverage for anterior soft tissue deficits of the knee.

Limb Salvage After Infected Knee Arthroplasty With Bone Loss and Extensor Mechanism Deficiency Using a Modular Segmental Replacement System

Multiple total knee arthroplasty revisions pose significant surgical challenges, such as bone loss and soft tissue compromise. For patients with bone loss and extensor mechanism insufficiency after total knee arthroplasty, arthrodesis is a treatment option for the avoidance of amputation. However, arthrodesis is both difficult to achieve in situations with massive bone loss and potentially undesirable due to the dramatic shortening that follows. Although intramedullary nailing for knee arthrodesis has been widely reported, this technique has traditionally relied on the achievement of bony union. We report a case of a patient with massive segmental bone loss in which a modular intercalary prosthesis was used for arthrodesis to preserve limb length without bony union.

Extensor Mechanism Deficiency in Total Knee Arthroplasty

Extensor mechanism deficiency after total knee arthroplasty poses a therapeutic challenge to the orthopedic surgeon due to soft tissue compromise and the lack of reliable reconstruction techniques. Rupture can occur at the time of initial knee arthroplasty, immediately thereafter, or as a late complication. Non-operative treatment generally results in a poor outcome. Direct primary repair also leads to high failure rates, and it should be avoided in complex cases. Reconstructive options include autograft with semitendinosus tendon, medial gastrocnemius muscle transposition flap, achilles tendon allograft, or patellar composite graft. Bony fixation should always be sought-after, as it gives more reliable healing rates. The success of the reconstruction basically begins with a well-fixed, well-aligned, underlying arthroplasty.

Allograft-Prosthetic Composite Reconstruction of the Proximal Part of the Tibia

Allograft-prosthetic composite reconstruction of the proximal part of the tibia is one option following resection of a skeletal tumor. Previous studies with use of this technique have found a high prevalence of complications, including fracture, infection, extensor mechanism insufficiency, and loosening. To address some of these problems, we adopted certain measures, including muscle flap coverage, meticulous tendon reconstruction, rigid implant fixation, and careful rehabilitation. The goal of the present study was to evaluate the functional outcome and complications in patients undergoing allograft-prosthetic composite reconstruction of the proximal part of the tibia. Twelve patients who underwent allograft-prosthetic composite reconstruction of the proximal part of the tibia after tumor resection were retrospectively evaluated at a median follow-up of forty-nine months. Clinical records and radiographs were reviewed to evaluate patient outcome, healing at the allograft-host junction, function, construct survival, and complications. Nine patients had no extensor lag, and three patients had 5 degrees to 15 degrees of extensor lag. The mean amount of knee flexion was 103 degrees (range, 60 degrees to 120 degrees ). The mean Musculoskeletal Tumor Society score was 24.3 (81%) of a maximum of 30. Complete bone union occurred in nine patients, and partial union occurred in three patients. At the time of writing, no secondary bone-grafting procedures had been required to achieve union, and no revision or removal of the reconstruction had been performed. Rotational or free flaps provided satisfactory wound coverage in all patients. A deep infection occurred in one patient whose allograft and prosthesis were successfully retained after treatment with surgical débridement and intravenous antibiotics. After osteoarticular resection of destructive tumors of the proximal part of the tibia, an allograft-prosthetic composite reconstruction can provide consistently good functional results with an acceptably low complication rate. Technical aspects of the procedure that may favorably affect outcome include soft-tissue coverage with muscle flaps and rigid fixation with a long-stemmed implant.

Knee stabilisation following infected knee arthroplasty with bone loss and extensor mechanism impairment using a modular cemented nail

Infected Total Knee Replacement with significant bone loss and loss of extensor mechanism poses a difficult management problem. Arthrodesis relying on bony union can be difficult to achieve and can result in significant limb shortening. We retrospectively looked at the outcome of seven patients with significant bone loss and extensor mechanism insufficiency following infected TKR who underwent knee stabilisation using a modular cemented nail. The nail relied on the strong coupling mechanism between the modular femoral and tibial components. Pain score improved from a mean of 7.9 pre-operatively to 1.5 post-operatively at a mean follow up of 39.6 months (range 7–68) months. Two patients underwent technically easy revision nailing for recurrent infection and aseptic loosening. The Endo-Model® Knee Fusion Nail (Newsplint, UK/Waldemar Link®, GmbH & Co. KG, Hamburg, Germany) has good early results in terms of pain relief and provides a stable knee in cases with significant bone loss and extensor mechanism insufficiency following an infected TKR thus avoiding an above knee amputation.

Rekonstruktion des Streckapparats mittels freiem, allogenem, gefriergetrocknetem Patellatransplantat

Allograft reconstruction of a deficient extensor mechanism is sufficient using an allogenic, freeze-dried patellar graft sterilized with peracetic acid. The reduced risk of infection is an advantage over fresh-frozen grafts.

Outcome of allogeneic vascularized knee transplants

Transplantation of vascularized knee joints is a novel approach in Composite Tissue Allotransplantation (CTA). In 1996 our group started a clinical knee transplantation project and six transplantations have been performed since. Key problems identified early were the monitoring of acute rejection and choice of an immunosuppressive regime. One graft was lost due to postoperative infection and one due to of noncompliance where the patient discontinued the immunosuppressant regime. In three cases late rejection lead to necrosis and graft dysfunction after 15, 16 and 24 months, respectively. Exit-strategies were arthrodesis in one patient and Above Knee Amputation in two cases. With retrospective analysis after initial five cases the treatment protocol was improved. The immunosuppressive drug regime was altered, femoral diaphysis and knee joint grafting was combined and a vascularized block of donor skin and subcutaneous tissue was harvested with the graft (sentinel skin graft). The sentinel skin graft enabled us to monitor acute rejection by clinical and histological examination and avoid late rejection by rapid treatment with high dose steroids. In summary, over a four-year period, one of six allogeneic vascularized knee transplants has survived, one was lost from a surgical site infection, one by noncompliance and three by late rejection. Analysis of our data leads us to suggest that knee transplantation should be limited to a combined injury consisting of extensive loss of cartilage and bone, deficient extensor mechanism and soft tissue and skin defects without any signs of infection. Transplantation should only be taken into consideration as last option before Above Knee Amputation in an otherwise healthy patient under 35 years of age.

Stanmore non-invasive growing arthrodesis endoprosthesis in the reconstruction of complicated total knee arthroplasty: A case report

As the number of primary and revision arthroplasties performed each year increases, the complexity of the reconstructive efforts also increases. A case of a patient with a total knee arthroplasty complicated with infection, deficient extensor mechanism, bone loss and limb shortening of 5.5 cm is reported. We describe an alternative surgical technique of reconstruction of the knee and lengthening of the limb using the Stanmore Non-Invasive Growing-Distal Femoral Prosthesis. The prosthesis had a magnetic disc attached to a gearbox. The generation of an external electromagnetic field caused the magnetic disc to rotate and lengthen the prosthesis. This reconstructive technique has not been described in the literature.

Use of Leeds–Keio Connective Tissue Prosthesis (L–K CTP) for reconstruction of deficient extensor mechanism with total knee replacement

Purpose This study was carried out in order to assess the results of reconstruction of a deficient extensor mechanism in the presence of a total knee replacement (TKR) using the Leeds–Keio Connective Tissue Prosthesis (L–K CTP). Methods and results The L–K CTP is available as flat tapes constructed from polyester in an open weave structure. It was used to reinforce and reconstruct the extensor mechanism, which was deficient in three patients who had undergone total knee replacement or were about to undergo total knee replacement. Two cases had extensor mechanism deficiency as a complication following total knee replacement while the third case had extensor mechanism deficiency at the time of the primary knee replacement. The average follow-up was 2 years (range of follow up was 12 to 48 months). All three cases showed good results with no extension lag and good range of movement at follow up. Conclusion The use of L–K CTP for reconstruction of the knee extensor mechanism offers a good option for the management of the uncommon but difficult problem of extensor mechanism deficiency in patients with a total knee replacement.

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.

Why knees fail: Lessons learned

This article reviews the changing modes of failure in total knee arthroplasty over the past decade. Reasons for failure include polyethylene wear, aseptic loosening, instability, infection, arthrofibrosis, malalignment, or malposition, deficient extensor mechanism, periprosthetic fracture, and isolated patellar resurfacing. Awareness of the modes of failure may lower the prevalence of failure and aid in developing designs and techniques to better address the problems.

Salvage of infected total knee fusion: the last option.

Currently the most common indication for an arthrodesis of the knee is a failed infected total knee prosthesis. Other causes of a failed total knee replacement that might necessitate a knee fusion include aseptic loosening, deficient extensor mechanism, poor soft tissues, and Charcot joint. Techniques available for achieving a knee fusion are external fixation and internal fixation methods. The external fixation compression devices have been the most widely used for knee fusion and have been successful until the indications for fusion changed to mostly failed prosthetic knee replacement. With failed total knee replacement, the problem of severe bone loss became an issue, and the external fixation compression devices, even including the biplane external fixators, have been the least successful method reported for gaining fusion. The Ilizarov technique has been shown to achieve rigid fixation despite this bone loss, and a review of reports are showing high fusion rates using this method. Internal fixation methods including plate fixation and intramedullary nails have had the best success in gaining fusion in the face of this bone loss and have replaced external fixation methods as the technique of choice for knee fusion when severe bone loss is present. A review of the literature and a discussion of different fusion techniques are presented including a discussion of the influence that infection has on the success of fusion.

Insall Award paper. Why are total knee arthroplasties failing today?

The incidence of failure after knee replacement is low, yet it has been reported that more than 22,000 knee replacements are revised yearly. The purpose of the current study was to determine current mechanisms of failure of total knee arthroplasties. A retrospective review was done on all patients who had revision total knee arthroplasty during a 3-year period (September 1997-October 2000) at one institution. The preoperative evaluation in conjunction with radiographs, laboratory data, and intraoperative findings were used to determine causes of failure. Two hundred twelve surgeries were done on 203 patients (nine patients had bilateral surgeries). The reasons for failure listed in order of prevalence among the patients in this study include polyethylene wear, aseptic loosening, instability, infection, arthrofibrosis, malalignment or malposition, deficient extensor mechanism, avascular necrosis in the patella, periprosthetic fracture, and isolated patellar resurfacing. The cases reviewed included patients who had revision surgery within 9 days to 28 years (average, 3.7 years) after the previous surgery. More than half of the revisions in this group of patients were done less than 2 years after the index operation. Fifty percent of early revision total knee arthroplasties in this series were related to instability, malalignment or malposition, and failure of fixation.

Preoperative Planning in Revision Knee Arthroplasty: An Overview

Summary: Total knee arthroplasty (TKA) has proven to be one of the most costeffective procedures that a patient with end-stage knee disease can receive. With improvement in prosthetic design, instrumentation, surgical technique, and rehabilitation, long-term results have been excellent. As a result of the improved functional outcome and an aging population, the number of primary TKAs performed in North America now exceeds the number of primary hip arthroplasties. Concomitant to the increased prevalence of primary TKA, however, there has been a greater need for total knee arthroplasty revision. Although aseptic failure is relatively uncommon, poor surgical technique and inadequate prosthetic design are responsible for most indications for revision knee surgery. In a failed TKA, it is imperative that the surgeon initially defines the mode of failure of the implant. The most common causes of aseptic failure are loosening, with or without component malalignment, polyethylene wear, ligament instability, extensor mechanism insufficiency, and arthrofibrosis. This article highlights tactics in preoperative planning and provides an overview of the rationale behind surgical exposure, implant removal, bone defect appraisal, ligament balancing and augmentation, reimplantation, and wound closure in total knee arthroplasty revision.