High meniscal allograft transplant survivorship shown at 10 years

Histological studies showed a 76% match between allograft and recipient DNA, indicating the presence of recipient-derived meniscal cells.

Issue: Issue 4 2006

Meniscal allograft implantation shows good survivorship rates and strong clinical outcomes at 10-year follow-up, according to a study by researchers in Belgium.

However, long-term data remain scarce and further study is needed, noted Peter Verdonk, MD, an orthopaedic surgeon at Ghent University Hospital and lead author of the study.

Verdonk and colleagues at the center performed a survivorship analysis of 100 viable meniscal allograft implantation procedures. They published the results in the American edition of the Journal of Bone and Joint Surgery. Verdonk presented the results of a new analysis of 12.1-year mean follow-up data at the 6th Symposium of the International Cartilage Repair Society in San Diego.

Peter Verdonk, MD [photo]
Peter Verdonk

“Nowadays, meniscus allografts remain the gold standard, although I believe that more and more in the future we’ll be hearing about scaffolds,” Verdonk said, noting deep freezing and cryo preservation are currently the most popular techniques.

Clinicians have abandoned lyophilization and autografts and have foregone the use of patches in favor of meniscal allografts, he added.

Indications for meniscal allograft implantation include younger patients with a previous total meniscectomy, moderate-to-severe post-meniscectomy pain and limited cartilage degeneration.

“We always perform our surgery open,” Verdonk said. “Many of the Americans, I think, are more prone to the arthroscopic way. The reason why we prefer open surgery with no bone plugs is that we think sizing is more adaptable, and the open way ensures good fixation without the all-inside suture technique.”

Good alignment is critical to transplant success, he noted, explaining that poor alignment requires an osteotomy or ACL reconstruction for joint stabilization.

Survivorship

In the earlier survivorship analysis, Verdonk studied clinical outcomes with a mean 7.3-year follow-up. The 100 procedures (96 patients) involved 39 medial allografts and 61 lateral allografts. The medial allograft subgroup included 20 isolated transplants and 13 associated with high tibial osteotomy. The lateral allograft subset included 49 isolated transplants.

All subgroups showed significantly improved pain scores at final follow-up compared with preoperative scores, Verdonk said. “This was also true for function, which was still significantly improved at final follow-up.”

Survivorship analysis showed that 74.2% of medial allografts and 69% of lateral allografts maintained function at 10 years, Verdonk said. The researchers also found that 70.2% of isolated allografts and 83% of medial allografts coupled with high tibial osteotomy survived at 10 years.

A radiograph of a transplanted meniscal allograft 12 years after surgery. Orthopaedic surgeon Peter Verdonk, MD, has seen pain relief and good function up to 10 years. However, longer-term outcomes are unknown.

Image: Verdonk P

Patients whose allografts failed because of degeneration or tearing were referred for allograft resectioning or resuturing. Other failed patients were converted to total or unicompartmental knee arthroplasty, Verdonk said.

Long-term follow-up

In the new analysis, researchers analyzed the long-term clinical data as well as MRIs and radiographic images at a mean 12.1-year follow-up. For clinical evaluations, they used the Knee Society scores and the Knee and Osteoarthritis Outcome Score (KOOS). Joint space narrowing and Fairbank changes were evaluated radiologically, while the status of the allograft and articular cartilage was evaluated using MRI.

The study included 39 allografts: 15 lateral and 24 medial. The medial group included 11 cases associated with high tibial osteotomy, Verdonk said, noting that he and his colleagues studied the groups separately.

At final follow-up, they found that clinical outcomes were significantly improved. “That’s more than 10 years postoperatively, for all groups, both in pain and in function,” Verdonk said.

However, radiographic studies showed mixed results at 10 years follow-up. For example, 41% of patients had no joint space narrowing, while 34% had narrowing by one grade, 22% had narrowing by two grades and 3% had narrowing by three grades, he said.

MRIs showed 47% of cases with no progressive femoral cartilage degeneration, 29% with one grade of degeneration, 12% with 1.5-grade degeneration and 6% with two-grade degeneration. On the tibial side, 41% had no progressive degeneration, 18% degenerated by half a grade, 23% by one grade and 12% by 1.5 grades.

Combined femoral and tibial data showed no progression in 35% of cases after surgery, Verdonk noted.

Postoperative histological studies of biopsy specimens showed a 76% match between allograft and recipient DNA, indicating the presence of recipient-derived meniscal cells. However, 25% of cases showed a “mix” of donor and recipient DNA, and only 8% showed donor DNA alone within the transplant, suggesting slow cell ingrowth.

Deep-frozen grafts showed only superficial cell growth. Preliminary evidence suggests that viable grafts had considerably more cell repopulation. However, there are no proven differences between frozen and viable allografts in humans at this point, Verdonk said.

“Meniscal allografts do reduce pain and improve function in 70% of patients in 10 years,” he said. “If associated with a high tibial osteotomy to correct poor varus alignment, this was up to 83% [survivorship]. Maybe we’ll start seeing some indications for chondroprotection.”

For more information:
Verdonk P, Demurie A, Almqvist K, et al. Meniscal allograft transplantation: long-term clinical results in Europe. Presented at the 6th Symposium of the International Cartilage Repair Society. Jan. 8-11, 2006. San Diego.