Interpositional meniscal allograft for glenoid resurfacing buys patients time

SAN FRANCISCO — Fixing lateral meniscal allografts to young patients' glenoids provides satisfactory pain relief and improved function and quality of life at short-term follow-up.

During the American Academy of Orthopaedic Surgeons 75th Annual Meeting, here, Michael A. Wirth, MD, reported his results using this method of biologic glenoid resurfacing in conjunction with shoulder hemiarthroplasty in 28 patients with 2 years minimum follow-up among 40 consecutive cases.

"The Visual Analog Scale (VAS) scores for pain, function and quality of life all improved," Wirth said, noting that Simple Shoulder Test (SST) results at final follow-up evaluation were also significantly better (P<.001).

"Immediate postoperative radiographs revealed a mean glenohumeral joint space of 3.5 mm compared to 1.7 mm at most recent follow-up. No glenoid erosion was seen in any of the shoulders," he said.

Validated outcomes

Most patients Wirth treated with the combined arthroplasty/resurfacing approach for the humerus and glenoid were diagnosed with osteoarthritis or post-traumatic osteoarthritis of the glenohumeral joint (mean age 43 years).

He performed the procedures in conjunction with a shoulder hemiarthroplasty and prospectively followed patients with such validated outcomes measures as the American Shoulder and Elbow Surgeons Score, SST and VAS scores.

In discussing why meniscal allografts are suitable for this application, Wirth said, "This is a compliant structure with concave surface that matches nicely with the convex prosthetic head. The circular shape provides substantial coverage and studies would support the use of meniscal allograft showing that the areas of the cartilage covered by the graft showed substantially less arthritic changes."

Surgical technique

Wirth forms the allograft into an oval similar in size and shape to the glenoid it will cover. He uses a total shoulder arthroplasty glenoid sizing disc as a guide and to ensure the graft fits the glenoid. Wirth then marks the sites where the meniscus will be fixed.

"Sutures are placed through the existing labrum. If there is no labrum left, suture anchors are used," Wirth explained. He then reams the glenoid and if he sees no bleeding he microfractures the subchondral bone in the area where the graft will lay.

Wirth fixes the allografts via a parachuting technique, placing sutures around the graft's edges. He also used three segmenting sutures to suspend the meniscus above the wound before he sutured it in place.

"Fixation is analogous to the method for aortic or mitral valve replacement," he said.

According to Wirth, "The parachuting technique for interposition resurfacing of the glenoid facilitated graft application and provided secure fixation."

Two patients' outcomes worsened progressively by 14 months postop, average. He said one of those allografts thinned, wore and markedly frayed.

For more information:
Michael A. Wirth, MD, can be reached at University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78284-6200; 210-567-5125; e-mail: wirth@uthscsa.edu. He is a consultant to and receives royalties from DePuy, a Johnson & Johnson company, institutional support from Smith & Nephew and Stryker and has stock/stock options with Tornier.

Reference:
Wirth MA. Meniscal allograft glenoid resurfacing in conjunction with HA: 1-5 years follow-up. Paper #10. Presented at the American Academy of Orthopaedic Surgeons 75th Annual Meeting. March 5-9, 2008. San Francisco.