Marlex Mesh Reconstruction of Extensor Mechanism Disruption in Total Knee Arthroplasty





Introduction


Extensor mechanism injuries after total knee arthroplasty (TKA) are dramatic and can occur in up to 12% of all TKAs. Injuries to the extensor mechanism can occur at the quadriceps tendon, the patella itself in the form of a fracture, or patellar tendon, and they may be acute or chronic injuries. Most extensor mechanism disruptions occur postoperatively, but an intraoperative extensor mechanism disruption may occur. Extensor mechanism disruptions lead to significant functional impairment including extensor lag, instability, and recurrent falls. There are several treatment strategies for these injuries, from primary repair and rotational muscle flaps to reconstructive techniques with allograft or synthetic materials. Outcomes after primary repair, particularly in chronic injuries, are unacceptably poor. Thus, reconstructive techniques have become widely adopted. ,


Three major reconstructive options exist: whole extensor mechanism allograft, Achilles tendon allograft, or reconstruction with a synthetic material. When a whole extensor mechanism allograft is used, it replaces the entire extensor mechanism, including the patella. The advantage of this technique is that several series have shown it leads to a decrease in the extensor lag, with improved functional outcome scores. However, the technique is limited by high costs, variable results, and concerns regarding availability, immune reaction, and disease transmission. In addition, there are concerns regarding infection and symptomatic lengthening of the graft. , , The advantage of Achilles tendon allograft is its length and the ability to retain the patella. It is advantageous in settings in which the patella can be brought down to within 4 cm of the joint or in cases of chronic quadriceps tendon ruptures that may have significant retraction. , However, there are similar concerns with Achilles tendon allografts as with whole extensor mechanism allografts.


At our institution, reconstruction of the extensor mechanism with a monofilament polypropylene mesh (Marlex mesh; C. R. Bard; Franklin Lakes, NJ) is the preferred technique for all extensor mechanism injuries. The advantage of Marlex mesh is that it avoids the allograft limitations, can be performed efficiently, is significantly cheaper, and leads to good midterm functional outcomes. The purpose of this chapter is to review extensor mechanism disruptions, how to avoid these injuries, and how to effectively treat them with an extensor mechanism reconstruction utilizing Marlex mesh. In addition, we will review the surgical technique, provide practical surgical tips and tricks to avoid failure, and provide an example of how to treat a failure of Marlex mesh.


Intraoperative Extensor Mechanism Disruption


Intraoperative extensor mechanism disruptions are uncommon but may occur in difficult primary TKAs or revision TKAs. The patellar tendon may be injured when the exposure is challenging, such as in cases of patella baja or arthrofibrosis, and the injury can be mid-substance in nature or avulsed off of the tibial tubercle as a result of forceful retraction. The quadriceps tendon may be disrupted. Patella fractures are rare but may occur when resecting too much patella for resurfacing. Regardless, the key is prevention with adequate basic and advanced exposure techniques. Proper release of all adhesions and cleaning out of the medial and lateral gutters can greatly enhance exposure. A quadriceps snip should be used to help release tension off of the extensor mechanism in cases with difficult exposures. If needed, albeit rarely, a tibial tubercle osteotomy may be utilized as well.


In the event of an intraoperative extensor mechanism injury, the key is recognition. Historically, an isolated primary repair was advocated for after an intraoperative extensor mechanism disruption. Yet, failure remains unacceptably high at a rate of greater than 50%. For a mid-substance patellar tendon injury, an end-to-end repair with a nonabsorbable suture is commonly advocated. For insertional patellar tendon ruptures, drill holes, suture anchors, or staples may be used. However, in the senior author’s opinion (MPA), all methods of primary repair should be augmented with Marlex mesh and a reconstruction, given the very high rates of failure with primary repair. ,


Intraoperative quadriceps tendon tears are less common. Partial ruptures may be treated with repair and immobilization. However, complete ruptures require reconstruction. Several series have suggested that early quadriceps tendon ruptures may be treated with repair alone. Yet, failure rates are similarly high in primary repair of quadriceps tendon ruptures as they are in patellar tendon ruptures. As such, we similarly recommend an extensor mechanism reconstruction with Marlex mesh for intraoperative quadriceps tendon injuries.


Postoperative Extensor Mechanism Disruption


Postoperative extensor mechanism disruptions are more common than intraoperative disruptions. These may be acute injuries or chronic injuries. In the early postoperative period, patients typically present with a traumatic event, such as a fall on a flexed knee. Chronic extensor mechanism disruptions may be due to trauma or other factors such as systemic conditions (e.g., diabetes mellitus, rheumatoid arthritis, or renal disease), vascular insult, implant malposition, or instability. , Similar to intraoperative extensor mechanism disruptions, identification of the injury is critical. For the majority of patients, a focused clinical examination can diagnose the injury. Patients typically present with quadriceps weakness and may have associated pain and instability. On examination, they have an extensor lag, quadriceps weakness, and may have a palpable defect. Plain radiographs may also assist with the diagnosis. Patella baja suggests quadriceps tendon rupture and patella alta suggests patellar tendon injury. In cases of an equivocal clinical exam and radiographs, advanced imaging such as ultrasound (US) or magnetic resonance imaging (MRI) may assist in the diagnosis.


A postoperative extensor mechanism disruption, whether acute or chronic, is treated with reconstruction utilizing Marlex mesh at our institution. The concern in chronic cases is that the tissue is of poor quality and will not tolerate a primary repair.


Surgical Technique and Rehabilitation—A Case Example


We present the case of a postoperative chronic extensor mechanism disruption with a concurrent periprosthetic joint infection (PJI). A 67-year-old male presented to our hospital with a complex surgical history of the left knee. He had a left primary TKA that was complicated by persistent drainage postoperatively at an outside institution. He had two irrigation-and-debridement treatments postoperatively, both with negative cultures. He was treated with intravenous daptomycin for 6 weeks followed by oral suppression with doxycycline. Six months postoperatively, he developed methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. His TKA was explanted and an antibiotic-loaded bone cement (ALBC) spacer was placed. He presented to our institution 1 year after his primary TKA with his ALBC spacer in place.


On exam, he walked with an antalgic gait, favoring the contralateral side. His range of motion was from 10 to 80 degrees. His exam was concerning for extensor mechanism disruption due to significant quadriceps weakness and a 40-degree extensor lag. His preoperative radiographs demonstrated a dislodged articulating spacer with foreign debris ( Fig. 14.1 ). His C-reactive protein (CRP) was 21 mg/L and his erythrocyte sedimentation rate was 70. An aspiration was performed with a synovial white blood cell count of 6013 cells/10 –3 cm . The plan was for a repeat resection arthroplasty, debridement, and placement of ALBC spacer. In the operating room (OR), gross purulence and an extensor mechanism disruption were appreciated. As such, an irrigation and debridement with placement of a new static ALBC spacer was executed. The patient returned to the OR 4 months later for a reimplantation and extensor mechanism reconstruction with Marlex mesh as described most recently by Abdel et al. ,




Fig. 14.1


Preoperative radiographs of patient with a periprosthetic joint infection and concomitant symptomatic lengthening of the extensor mechanism. Anteroposterior (A), lateral (B), and sunrise (C) radiographs of the left knee demonstrating a dislodged antibiotic spacer with patella baja.


The technique was rather simple at the time of reimplantation. Prior to incision, a 10″ × 14″ sheet of monofilament polypropylene graft (Marlex Mesh, Bard Inc.) was prepared by folding on itself 8 to 10 times to make a tubular structure. It was then secured with a heavy nonabsorbable suture ( Fig. 14.2 ). After skin incision, full-thickness subcutaneous flaps were developed both medially and laterally. A traditional medial parapatellar arthrotomy was then performed. As in all cases of an extensor mechanism reconstruction, we performed a synovectomy and developed the medial and lateral gutters. The patient’s extensor mechanism was then identified. The ALBC spacer was then resected, and appropriate cuts were made for a rotating-hinge (RH) TKA, which is the preference of the senior author (MPA) when completing a Marlex mesh reconstruction. It is also the senior author’s preference to cement 5 cm of the Marlex mesh into the tibial canal with the revision tibial component instead of creating a tibial trough.




Fig. 14.2


A, Bard Marlex mesh composed of monofilament polypropylene. B, 10″ × 14″ Marlex mesh sheet. C, Marlex mesh sheet folded over itself approximately 10 times. D, Marlex mesh sheet folded and secured by nonabsorbable heavy suture.


In this case, the Marlex mesh was then cemented along with the revision tibial component ( Fig. 14.3 ). Antibiotic cement containing 1 g of vancomycin and 1.2 g of gentamicin per 40 g bag of Simplex (Stryker) cement was used. The mesh was then tunneled proximally with soft tissue covering the mesh both ventrally and dorsally ( Figs. 14.4 and 14.5 ) utilizing the remnant patellar tendon. The mesh was then brought proximally and tunneled through the soft tissue superficial to the patella.




Fig. 14.3


Marlex mesh is cemented into the tibial canal anteriorly along with the revised tibial component.



Fig. 14.4


Marlex mesh is covered by soft tissue both ventrally and dorsally.

Jun 18, 2022 | Posted by in ORTHOPEDIC | Comments Off on Marlex Mesh Reconstruction of Extensor Mechanism Disruption in Total Knee Arthroplasty

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