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Synthetic mesh extensor mechanism reconstruction after TKA can yield good functional outcomes
James A. Browne, MD, discussed treatment options for extensor mechanism disruption following total knee arthroplasty and factors that may lead to failure. He said the mainstays of extensor mechanism reconstruction include whole extensor allograft, Achilles allograft and synthetic mesh, all of which can be successful, but have an expected failure rate given the difficulty of this problem.
“The synthetic mesh procedure is my procedure of choice,” Browne said at a meeting. “It is technically simple, cost-effective, it avoids some of the concerns with allograft and I think the mid-term results are reasonable.”
When using a synthetic mesh graft during reconstruction, Browne noted wound break-down can be problem if the entire mesh is not covered with host tissue.
“If you leave some of this mesh exposed, the wound will break down,” he said. “Whether you use mesh or allograft, I think it is critical to put these in as tight as you can get them, keep the knee out straight, do not flex the knee. We learned that lesson with cadaver [tissue] and I think it is critically important as well with mesh.”
Patients undergoing extensor mechanism reconstruction should be put in a cast for 3 months, which is important to discuss with the patient before surgery, Browne said.
“The patient has to be ready to be in a cast for 3 months and that is non-negotiable in my practice,” he said.
Patients with unrecognized or recognized flexion instability may be predisposed to subsequent failure of an extensor mechanism reconstruction, according to Browne. In published research of 13 patients with an isolated patellar tendon rupture, Browne said patients with successful reconstruction had good functional outcomes.
“There were three failures in this group. All failed within 6 months and all three of those patients had previous extensor mechanism reconstructions and were complex [cases],” he said.
Browne noted a report on a larger cohort of patients is about to be published and shows similar results.
In addition, he said concomitant periprosthetic joint infection (PJI) can lead to poor outcomes in these patients.. A published study of 60 patients with PJI and extensor mechanism disruption following TKA showed a successful outcome in 23% of patients, but many of the patients with recurrent PJI went on to arthrodesis, amputation or a resection. – by Casey Tingle
Reference:
Browne JA. Ruptured patella tendon. Presented at: Joint Arthroplasty Mountain Meeting; Feb. 10-13, 2019; Park City, Utah.
For more information:
James A. Browne, MD, can be reached at University of Virginia Health System, Musculoskeletal Center, 545 Ray C. Hunt Dr., Charlottesville, VA 22903; email: jab8hd@virginia.edu.
Disclosure: Browne reports he receives IP royalties from DJO Surgical, is a paid consultant for DJO Surgical, Novartis and OsteoRemedies, receives publishing royalties, financial or material support from Journal of Bone and Joint Surgery, Journal of Arthroplasty and Saunders/Mosby-Elsevier, and has stock or stock options with Radlink.
Perspective
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Extensor mechanism reconstruction using tubularized synthetic mesh is a cost-effective, versatile technique that effectively restores knee function for a variety of extensor mechanism deficiencies following knee arthroplasty. Advantages of synthetic mesh over traditional allografts include availability, no risk of disease transmission and maintenance of tensile strength, potentially reducing late tissue elongation and progressive extensor lag.
Browne highlights several key factors for success with this technique, including addressing any underlying component malpositioning at the time of revision and fully covering the mesh graft with host tissue in a “pants-over-vest” fashion. Avoiding intraoperative flexion once the graft is tensioned and strict postoperative compliance with prolonged immobilization in full extension are paramount. Low residual extensor lag and acceptable knee function can be expected at mid-term follow-up.
Rutgers Robert Wood Johnson Medical School