Surgical technique: vastus medialis and vastus lateralis as flap transfer for knee extensor mechanism deficiency

Very High Early Failure Rate Following Primary Repair of Acute Extensor Mechanism Disruption After Total Knee Arthroplasty

BACKGROUND

Extensor mechanism disruption is a devastating complication following total knee arthroplasty (TKA). Despite its morbidity, there is no consensus regarding the optimal treatment strategy. We aimed to determine the survivorship, clinical outcomes, and improvement in patient-reported outcome measures after primary repair of acute extensor mechanism disruptions following primary or revision TKA.

METHODS

A retrospective review identified 41 acute extensor mechanism disruptions (33 primary TKAs and eight revision TKAs) from 2015 to 2021. The study group was 56% women, the mean body mass index was 33, the mean age was 66 years, and the mean follow-up was 3 years. Extensor mechanism disruption occurred at the patellar tendon (n = 17), quadriceps tendon (n = 15), and patella (n = 9) at a mean of 10 months following TKA. Surgical management was primary repair (n = 30) or primary repair with augmentation (allograft or autograft) (n = 11). Kaplan-Meier analysis estimated survivorship.

RESULTS

The 2-year survivorship free from all-cause reoperation was 72 and 23% following primary and revision TKA, respectively (P = 0.013). The 2-year survivorship free from all-cause reoperation was 66% for primary repair versus 61% for primary repair with augmentation (P = 0.95). There were 17 (41%) patients who underwent reoperation, most commonly for rerupture (n = 4) in two primary repairs and two primary repairs with augmentation (P = 0.288). Revision TKA (P = 0.049) and increased time from disruption to repair (P = 0.039) were risk factors for reoperation. Neither did the mean extensor lag significantly improve nor did patients see improvement in their patient-reported outcome measures.

CONCLUSIONS

After primary and revision TKA, acute extensor mechanism disruption treated with primary repair with or without augmentation had very poor early survivorship free from all-cause reoperation. Patients should be counseled appropriately, and alternative surgical techniques should be considered.

Tips and Tricks to Save You During Revision Total Knee Arthroplasty

The number of revision total knee arthroplasties (TKAs) performed annually continues to rise. This article is a summary of a symposium on revision TKAs presented at the 2023 American Association of Hip and Knee Surgeons annual meeting. It will provide an overview of the surgical tips and tricks for exposure and component removal, use of metaphyseal fixation and stems to manage bone loss and optimize fixation, constraint in TKA, as well as how to manage extensor mechanism disruptions with a synthetic mesh reconstruction. LEVEL OF EVIDENCE: V.

A Systematic Review of Clinical Outcomes of Pedicled Flap Repairs of the Knee Extensor Mechanism

BACKGROUND

 Rupture of the extensor mechanism of the knee has severe functional morbidity, and repair can be complicated by infection, allograft degeneration, and recurrent rupture. Techniques of autologous tissue repair utilizing pedicled flaps such as the gastrocnemius offer vascularized methods of reconstruction, with potentially diminished complication rates. The goal of this study was to evaluate the functional outcomes and complications associated with pedicled flap repair of the knee extensor mechanism.

METHODS

 A systematic review was conducted following the Preferred Reporting Items for Systemic Reviews and Meta-Analyses guidelines. Publications that focused on local myocutaneous flaps as a means for reconstruction were included. Causes for knee extensor mechanism deficit, flap characteristics, ambulation rate, changes in range of motion pre- and postoperation, and postoperative complications were analyzed. Technique reports including primary suture repairs, synthetic mesh, and allograft use were excluded.

RESULTS

 An initial 119 studies were identified, with final review of 22 observational studies encompassing 128 cases of pedicled flap reconstructions. The gastrocnemius (88.2%, n = 113), quadriceps (6.3%, n = 8), and a combination of the vastus and gastrocnemius flaps (5.5%, n = 7), were the most frequently utilized flaps. Functional outcomes were favorable with 87.2% of patients achieving ambulation without external support. Variability in range of motion outcomes across different flap may be secondary to the patient characteristics as well as extent of initial injury.

CONCLUSIONS

 Autologous pedicle flap reconstruction of the knee extensor mechanism emerges as a viable option for cases characterized by extensive defects and insufficient soft tissue coverage, which are not amenable to direct suture repairs or allografts. Postoperative assessments revealed that the majority of patients experienced improved ambulation status, with no instances of deterioration noted among the patients.

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.

Pedicled Rectus Femoris Flap for Restoration of Suprapatellar Quadriceps Tendon and Defect Coverage after Multiple Reconstruction Attempts-A Case Report and Literature Review

There is no unified approach for restoring the suprapatellar quadriceps tendon and covering tissue defects simultaneously. In this case report, we present the pedicled myocutaneous rectus femoris flap as one effective approach in two cases with extensive loss or impairment of the suprapatellar muscle-tendon structures after trauma-related suprapatellar quadriceps tendon rupture and multiple reconstruction attempts. Additionally, we provide a literature review of the reconstructive use of the functional pedicled myocutaneous rectus femoris flap.

METHODS

Two male patients, 48 and 74 years old, with extensive loss or impairment of the suprapatellar muscle-tendon structures due to multiple reconstruction attempts, underwent restoration of the knee extension with a pedicled myocutaneous rectus femoris flap.

RESULTS

Three months after reconstruction, both patients were able to walk freely, unaided. After a six-month follow-up, the free passive mobility of the knee joint was restored, and the active extension of the knee joint was possible in both patients.

CONCLUSION

The authors conclude that the pedicled rectus femoris flap is a reliable method for the restoration of knee extension, with excellent functional results in cases of suprapatellar tendon lesions. Further to the functional restoration, this technique has the additional advantage of simultaneously achieving coverage of soft-tissue defects, while a direct closure of the donor site is possible. Elderly patients and patients with relevant comorbidities or multiple revisions may especially benefit from this technique.

Therapy of chronic extensor mechanism deficiency after total knee arthroplasty using a monofilament polypropylene mesh

Introduction

Lesions of the quadriceps or patellar tendon after total knee arthroplasty (TKA) are a rare but serious complication which, if left untreated, can lead to loss of function of the knee joint. While acute and subacute extensor mechanism disruptions may have several causes, chronic deficiencies are often related to multiple prior revision surgeries for joint infection or aseptic TKA failure. Up to date, biological allograft reconstruction showed unsatisfying results. The use of a monofilament polypropylene mesh is a promising approach for this pathological condition. The aim of the present study was to evaluate clinical, functional and patient reported outcomes of this procedure in patients with chronic extensor mechanism deficiency.

Materials and Methods

Twenty-eight patients with chronic extensor mechanism deficiency (quadriceps tendon rupture n = 9, patellar tendon rupture n = 19) after TKA were included in this retrospective study. None of the patients were lost to follow-up. Surgical reconstruction was performed at one institution between 2014 and 2020 with a monofilament polypropylene mesh (Marlex Mesh, Bard, Murray Hill, USA). The mean age at the time of surgery was 69 years. Patients presented with a mean BMI of 33 kg/m². The mean follow-up period was 23 months.

Results

The 2-year survivorship free of mesh revision was 89% [95% confidence interval (CI): 75% to 100%]. Three patients (11%) had to undergo revision because of mechanical mesh failure and received another polypropylene mesh. No further revisions were performed thereafter. Flexion was 87° (range, 30–120°) on average. The majority of patients (75%, 21/28) had a full active extension. The mean active extension lag after surgery was 4 degrees (range, 0–30°).

Discussion

We observed a substantial improvement of extensor mechanism function. The majority of patients had full extension and showed good clinical results. A failure rate of over 50% has been published for alternative procedures. Thus, the use of the described augmentation technique represents a reasonable treatment option for chronic extensor mechanism disruptions of the patellar tendon as well as the quadriceps tendon after total knee arthroplasty. However, there might be a potentially higher risk for infection persistence in periprosthetic joint infection cases due to the presence of a foreign material.

Soft Tissue Procedures in the Multiply Operated on Knee Replacement Patient

In the multiply operated on knee replacement, no one soft tissue procedure is vastly superior to another. The most extensive literature available is in relation to muscle flaps, which will continue to be the workhorse technique for orthopedic and plastic reconstructive surgeons for the foreseeable future. Closed incision negative pressure wound therapy may prove to be a superior method in time but further large-scale studies are required to expand our understanding of this technique. The continued use of a combination of these techniques, tailored to the specific patient, is likely to be the best approach to the multiply operated on knee into the future.

Customized reconstruction of a complex soft-tissue defect around the knee with a free perforator flap

Reconstruction of a complex defect around the knee, particularly involving a large soft-tissue defect or disruption of the extensor mechanism, is always a challenging problem. The purpose of this study was to introduce the use of a customized free perforator flap for complex soft-tissue reconstruction around the knee. Between June 2010 and March 2017, 16 patients underwent this procedure. The choice of flap design is based on the location of the wound, the required pedicle length, the missing tissue components and their volumes, and the risk of donor-site morbidity. The reconstruction was performed using anterolateral thigh perforator (ALTP) flaps in five cases, modified ALTP flaps in two cases, chimeric ALTP flaps in four cases, dual-skin paddle ALTP flaps in two cases, and chimeric thoracodorsal artery perforator flaps in two cases. Multiple perforator flaps and vascularized fascia lata were used in one case. All flaps survived postoperatively. No vascular congestion was observed, and partial necrosis was observed in only one case. Primary closure of the donor site was performed for all patients. At a mean follow-up time of 16.5 months, most cases showed satisfactory flap contours and acceptable functional outcomes. A free perforator flap is a reliable option for repairing complex soft-tissue defects in the knee region, especially when local and pedicled flaps are unavailable. Various flap designs allow for more individualized treatment approaches and can achieve better results.

[Status and treatment of knee extension device disruption after total knee arthroplasty]

Objective

To summarize the principle, classification, and treatment methods of knee extension device disruption after total knee arthroplasty (TKA).

Methods

By extensively consulted the relevant domestic and abroad literature, the principle, classification, and treatment methods of injury according to different parts of the knee extension device after TKA were summarized and analyzed.

Results

The knee extension device disruption after TKA mainly occurs in the quadriceps tendon, patella tendon, and patella. Once the knee extension device is injured, it will seriously affect the functional recovery of the patient after surgery, resulting in delayed knee extension, limited range of motion, difficulty walking, and joint pain, etc. The current treatment methods are diverse, including conservative treatment and surgical treatment. Surgical treatment includes direct suture repair (traditional perosseous fixation and suture anchoring techniques), reconstruction and reinforcement repair (reconstruction using synthetic patches, autografts, and allografts). For the treatment of different parts, it is necessary to comprehensively consider the patient's knee joint tissue condition, the presence or absence of underlying diseases, and the presence or absence of donors.

Conclusion

There is no uniform conclusion on the treatment of knee extension device disruption after TKA. Different injury situations need to be considered comprehensively to choose the appropriate treatment method.

Adductor magnus muscle transfer to restore knee extension: Anatomical studies and clinical applications

BACKGROUND

Loss of knee extension causes significant impairment. Though nerve-based reconstruction is preferable in cases of femoral nerve palsy or injury, these surgeries are not always appropriate if the pathology involves the quadriceps muscles or presentation too late for muscle reinnervation. Muscle transfers are another option that has been underutilized in the lower extremity. We describe the successful restoration of knee extension by adductor magnus muscle transfer without functional donor morbidity, along with anatomical considerations.

METHODS

Ten fresh frozen cadaveric lower limbs were dissected at the groin and thigh. In addition, three patients presented with femoral nerve palsy for which nerve-based reconstruction was not appropriate because of late presentation. In these patients, adductor magnus muscle transfers were performed, along with sartorius, gracilis, and tensor fasciae latae transfers if available and healthy.

RESULTS

In cadavers, the pedicle for the adductor magnus is at the level of the gracilis and adequate for muscle transfer, with sufficient weavable tendon length. The only major structure at risk is the femoral neurovascular bundle, which is in a reliable anatomic position. Two patients recovered 4/5 active knee extension and ambulation without assistive devices. A third required reoperation for a loosened tendon weave, after which the noted improved stability and strength with ambulation but did not regain strong active knee extension and continued to require a cane.

CONCLUSIONS

We present a novel reconstructive approach for loss of quadriceps function in patients, which yields good clinical outcomes, with anatomic and technical details to demonstrate the utility of this technique. Ongoing evaluation of optimal technique and rehabilitation to maximize functional outcomes is still needed.

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.

Management Options for Extensor Mechanism Discontinuity in Patients With Total Knee Arthroplasty

Extensor mechanism disruption is one of the most dreaded complications of total knee arthroplasty. At times, the disruption is associated with infection, the paucity of soft tissue, and loosening of implants. Treatment decisions made by surgeons are guided by their experience and expertise. The purpose of this article is to provide the readers with an evidence-based comprehensive review which, in turn, should help them in diagnosis and selecting the best treatment strategy for individual patients. In the following article, we have discussed extensor mechanism disruptions of varying severity at various anatomical levels. We also covered both operative and non-operative measures in different clinical situations. The analysis of various articles published in the literature would also help orthopedic surgeons to understand the probable outcomes of the particular treatment option chosen and to counsel their patients accordingly.

Total Knee Arthroplasty Wound Complication Treatment Algorithm: Current Soft Tissue Coverage Options

BACKGROUND

Wound complications associated with soft tissue defects following total knee arthroplasty present challenges for the orthopedic surgeon. The scale of early complications include less morbid problems, such as quickly resolving drainage and small superficial eschars, to persistent drainage and full-thickness tissue necrosis, which may require advanced soft tissue coverage.

METHODS

This review outlines current wound management strategies and provides an algorithm to help guide treatment and clinical decision-making.

CONCLUSION

A surgeon's understanding of soft tissue coverage options is essential in protecting the knee prosthesis from a deep infection and to obtain an optimal functional outcome.

Treatment of deep cavities using a perforator-based island flap with partial de-epithelization

Background

The perforator-based island flap is a popular option for defect coverage. In cases with deep cavities, however, the classical island flap may not be a suitable option. By de-epithelization of the peripheral portion of a perforator-based island flap, the distal part of the flap can be used to fill deep spaces, as the flap can be folded and inserted into the spaces.

Methods

From June 2015 to April 2017, 21 cases of deep internal defects were reconstructed with perforator-based island flaps with peripheral de-epithelization. A fasciocutaneous flap was elevated and rotated with the pivot point on the perforator. After performing de-epithelization on the periphery of the flap, the de-epithelized portion of the flap was inserted and anchored into the internal defect. Demographic information about the patients, the size of the defects, the perforators that were used, and complications were recorded.

Results

During the follow-up period (mean, 14.2 months) of total 21 cases, no major complications such as flap loss occurred. In 2 cases, a minor complication was observed. Temporary flap congestion was seen in 1 case, and was treated with a short period of leech therapy, and the other case was partial necrosis on the flap margin, which was cured with minimal debridement and conservative treatment. No major problems have occurred, especially on the de-epithelized part of the flap and in the occupied space.

Conclusions

With performing careful procedure, a perforator-based island flap with partial de-epithelization can be a useful option for the surgical treatment of deep cavities.

Trial registration

This study was retrospectively registered in the institutional review board on human subjects research and the ethics committee, Hanyang University Guri Hospital (Institutional Review Board File No. 2018–01–003-002 https://www.e-irb.com:3443/devlpg/nlpgS200.jsp).

Treatment of Periprosthetic Knee Infection With Concurrent Rotational Muscle Flap Coverage Is Associated With High Failure Rates

BACKGROUND

Soft-tissue deficiency is a potentially devastating complication of the infected total knee arthroplasty (TKA). Rotational muscle flaps are commonly used to address these defects. However, reported success rates vary widely.

METHODS

We reviewed 26 consecutive patients who underwent rotational muscle flap surgery for full-thickness anterior soft-tissue defect during treatment of an infected TKA. Twenty-four cases used a medial gastrocnemius rotational flap, 1 used a lateral gastrocnemius flap, and 1 used a rectus femoris-vastus intermedius flap. Implant survival, recurrence of infection, and limb survival were reported. Patient and procedural characteristics were tested for association with failure using χ² and Student t-test. Kaplan-Meier analysis was used to estimate the failure-free survival function.

RESULTS

Mean follow-up time was 3.3 years. Eighteen of 26 patients (69.2%) experienced recurrent infection requiring an average of 5.3 additional operations (range, 1-20). Five (19.2%) required arthrodesis while 6 (23.1%) eventually underwent above-the-knee amputation. Two patients (7.7%) died due to complications of revision surgery or persistent infection. Eleven patients (42.3%) were infection free with a retained prosthesis after treatment at a mean follow-up of 5.3 years (range, 0.7-18.0 years).

CONCLUSION

Rotational muscle flap coverage of soft-tissue defects in the setting of the infected TKA remains a viable salvage option. However, despite adequate tissue coverage, many patients experience recurrent infection requiring additional surgical treatment. Patients and surgeons should be aware of the potential high failure rates observed when treating these complex problems.

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.

[Patellar tendon injuries after total knee arthroplasty : Classification and management]

BACKGROUND

Ruptures of the patellar tendon after total knee arthroplasty represent a rare but severe complication, which in general requires surgical therapy.

OBJECTIVES

To implement a classification and correspondent therapy algorithm in consideration of the current literature for the treatment of patellar tendon ruptures after TKA.

MATERIAL AND METHODS

A review of the recent literature and the author's experience are summarized in a classification and correspondent therapy algorithm for the treatment of patellar tendon ruptures after TKA.

RESULTS

Ruptures of the patella tendon can be classified as avulsions (Type I), acute (Type II) and chronic ruptures (Type III). Avulsions are often of iatrogenic nature and can be sufficiently treated by transosseous refixation prior to implantation of the revision TKA. Acute ruptures of the patellar tendon can originate from trauma or intraoperative injury. The rupture can be restored by primary suture in combination with a wire cerclage in the case of good tendon quality and the absence of patient comorbidities (Type IIA). In the case of poor tendon quality or existing comorbidities (Type IIB) additional augmentation of the ruptured tendon, utilizing the autologous semitendinosus/gracilis tendon, is recommended. Chronic ruptures revealing a good patellar bone stock (Type IIIA) can be treated by a combination of a semitendinosus augmentation and a turndown quadriceps tendon flap. In the case of a poor patellar bone stock (Type IIIB) transpatellar fixation of the semitendinosus tendon is virtually impossible, so that an allograft augmentation or the use of a soft tissue muscle flap (i. e. the gastrocnemius flap) has to be considered. A failed complex reconstruction with or without infection (Type IIIC) is an invidious surgical task and needs to be addressed by the utilization of a muscle flap, an allograft or a patellectomy with or without arthrodesis.

Survivorship of Extensor Mechanism Allograft Reconstruction After Total Knee Arthroplasty

BACKGROUND

Extensor mechanism disruption remains a devastating complication after total knee arthroplasty. The purpose of this study is to describe the outcomes of extensor mechanism allograft (EMA) reconstruction in a large single-center case series.

METHODS

Consecutive patients with a previous total knee arthroplasty undergoing extensor mechanism reconstruction using a fresh-frozen EMA tensioned in full extension were identified retrospectively from single-center institutional database (N = 25 patients, 26 knees; mean follow-up 68 months [range 22-113 months]). The primary outcome was initial allograft failure, defined as removal of the allograft or extensor lag >30 degrees at most recent follow-up.

RESULTS

Sixty-nine percent (18/26) of knees had retained their initial allograft reconstruction at their latest follow-up despite reoperation rates of 58% (15/26). A younger age was significantly associated with failure of the initial allograft reconstruction. Knee Society Scores increased from 101 (38 standard deviation [SD]) to 116 (40 SD) at most recent follow-up for the group as a whole (P = .4). Patients undergoing a reoperation for any cause had lower Knee Society Scores (101 [SD 38] vs 138 [SD 32], respectively; P = .04) at most recent follow-up.

CONCLUSION

EMA reconstruction shows adequate overall intermediate-term survival; however, reoperation rates were high and associated with worse functional outcomes.

Soft-tissue Defects After Total Knee Arthroplasty: Management and Reconstruction

Wound healing complications associated with total knee arthroplasty present a considerable challenge to the orthopaedic surgeon. To ensure preservation of a functional joint, the management of periprosthetic soft-tissue defects around the knee requires rapid assessment, early and aggressive débridement, and durable, contoured coverage. Several reconstructive options are available to tailor soft-tissue coverage to the location, size, and depth of the wound. Special consideration should be given to the timing of the intervention, management of infection, and prosthesis salvage. The merits of each reconstructive option, including perforator, fasciocutaneous, muscular, and free microvascular flaps, should be weighed to select the most appropriate option. The proposed approach can guide surgeons in treating patients with these complex soft-tissue defects.

Extensor tendon ruptures after total knee arthroplasty

Extensor tendon rupture is a rare but serious complication after total knee arthroplasty (TKA) that impairs active knee extension, thereby severely affecting knee function. Surgery is usually required. Surgical options range from simple suturing to allograft reconstruction of the entire extensor mechanism and include intermediate methods such as reconstruction using neighbouring tendons or muscles, synthetic ligament implantation, and partial allograft repair. Simple suturing carries a high failure rate and should therefore be routinely combined with tissue augmentation using a neighbouring tendon or a synthetic ligament. After allograft reconstruction, outcomes are variable and long-term complications common. Salvage procedures for managing the most severe cases after allograft failure involve reconstruction using gastrocnemius or vastus flaps. Regardless of the technique used, suturing must be performed under tension, with the knee fully extended, and rehabilitation must be conducted with great caution. Weaknesses of available case-series studies include small sample sizes, heterogeneity, and inadequate follow-up duration. All treatment options are associated with substantial failure rates. The patient should be informed of this fact and plans made for a salvage option. Here, the main techniques and their outcomes are discussed, and a therapeutic strategy is suggested.

Development of a Novel Model for the Assessment of Dead-Space Management in Soft Tissue

Following extensive surgical debridement in the treatment of infection, a “dead space” can result following surgical closure that can fill with hematoma, an environment conducive to bacterial growth. The eradication of dead space is essential in order to prevent recurrent infection. This study describes a novel small animal model to investigate dead-space management in muscle tissue. Two absorbable test materials were implanted in each animal; beads of calcium sulfate alone, and beads loaded with vancomycin and tobramycin. In-life blood samples and radiographs were taken from each animal following implantation. Animals were sacrificed at 1, 7, 21, 42, and 63 days post-operatively (n = 4), and implant sites were analysed by micro-computed tomography, histology and immunohistochemistry. Complete resorption was confirmed radiographically at 3 weeks post-implantation. Histologically, the host tissue response to both materials was identical, and subsequent healing at the implant sites was observed with no dead space remaining. Vancomycin was not detected in blood serum. However, peak tobramycin levels were detected in all animals at 6 hours post-implantation with no detectable levels in any animals at 72 hours post implantation. Serological inflammatory cytokine expression for IL-6, TNF-α and IL-1β indicated no unusual inflammatory response to the implanted materials or surgical procedure. The model was found to be convenient and effective for the assessment of implant materials for management of dead space in muscle tissue. The two materials tested were effective in resolving the surgically created dead space, and did not elicit any unexpected adverse host response.

Open, combat-related loss, or disruption of the knee extensor mechanism: treatment strategies, classification, and outcomes

OBJECTIVE

To report the outcomes of repair or reconstruction of high-energy, open knee extensor disruption or loss due to combat-related injuries.

DESIGN

Retrospective review.

SETTING

Tertiary (Level/Role V) Military Treatment Facility.

PATIENTS

Fourteen consecutive patients who sustained 17 complex, open knee extensor mechanism injuries during combat operations between March 2003 and May 2012.

INTERVENTION

Primary repair or staged allograft extensor reconstruction after serial debridement and closure or soft tissue coverage.

MAIN OUTCOME MEASURES

Final knee range of motion, extensor lag, ambulatory ability and assist devices, and complications requiring reoperation or salvage procedure.

RESULTS

The open knee extensor mechanism injuries required a mean of 11 procedures per injury. At a mean final follow-up of 39 months (range, 12-89 months), all patients achieved regular community ambulation, with 36% requiring assist devices due to concomitant or bilateral injuries. Average knee flexion was 92 degrees, and 35% of extremities had an extensor lag >10 degrees; however, 6 of 9 extremities with allograft reconstructions had extensor lags of <10 degrees, and 5 had no extensor lag. The presence of a major periarticular or patellar fracture was significantly associated with the knee requiring a subsequent extensor mechanism allograft reconstruction procedure. One extremity each underwent knee arthrodesis or transfemoral amputation due to severe infection.

CONCLUSIONS

High-energy, open knee extensor mechanism injuries are severe and rarely occur in isolation, but limb salvage is generally successful after multiple procedures. Patients who required staged allograft reconstruction, despite high complication rates, generally had favorable results.

LEVEL OF EVIDENCE

Therapeutic level IV. See instructions for authors for a complete description of levels of evidence.

Surgical technique: Muscle transfer restores extensor function after failed patella-patellar tendon allograft

BACKGROUND

Extensor mechanism allograft provides an effective remedy for severe quadriceps deficiency caused by loss of the patella, patellar tendon, and quadriceps tendon in TKA. Late failure is common, however, and major quadriceps deficiency occurs after removal of the allograft material.

DESCRIPTION OF TECHNIQUE

Six human cadaver specimens were dissected to evaluate the feasibility of transferring the vastus medialis, vastus lateralis, and medial head of the gastrocnemius muscle to fill the defect caused by loss of the patella and extensor tendon mechanism after failure and removal of allograft material. Transfer of the medial and lateral vastus muscles with their distal attachments into the tibia achieved closure of the defect but did not provide robust tendon material to fill the defect in the anterior knee. The medial gastrocnemius muscle reached easily to the muscular portion of the vastus medialis and lateralis flaps and provided secure closure of the anterior knee and strong attachment of viable muscle and tendon.

METHODS

Five knees (five patients) with failed patella-patellar tendon allograft between August 2008 and April 2010 were repaired using this technique.

RESULTS

Mean extensor lag was 47° (range, 35°-62°) before surgery and improved to 12° (range, 5°-15°) 1 year after surgery.

CONCLUSIONS

These preliminary results suggest that the described muscle transfer technique may provide an approach to salvage the failed extensor mechanism allograft after TKA.