Meniscal allografts effective for severely arthritic knees

Concomitant procedures did not predict success or failure of the allograft.

Meniscus allograft transplants can survive in vivo up to seven years in the presence of severe chondromalacia and arthrosis, previously considered contraindications for the procedure, a new study shows.

Kevin R. Stone, MD, and colleagues at the Stone Research Foundation, San Francisco, conducted the prospective study. The researchers focused on allograft implant survival in patients with severe preoperative degenerative osteochondral changes despite failed joint debridement attempts.

“These results show that meniscal allograft transplantation can be used in higher-risk patients with reasonable expectations of allograft survival,” the authors said in the study, published in the journal Arthroscopy.

Although the study did not address whether the allografts functioned as normal menisci, “This study reveals that the previous contraindications of age and severity of arthrosis are overstated ...,” they noted.

Prospective study

The study included 47 meniscal allograft transplantations in 45 patients — 31 men and 14 women. Patients had a mean age of 48 years, with 25% aged older than 55 years, the authors noted. Follow-up averaged 5.8 years (range, two to 7.25 years), and no patients had less than two years’ follow-up, according to the study.

Patients had undergone an average of 2.1 prior surgeries. Using the Outerbridge (OB) classification system, nine cases had OB III and 38 cases had OB IV degenerative changes preoperatively. Of the 47 knees, 16 (36%) had severe joint space narrowing and 18 (40%) had moderate narrowing and 11 knees (24%) showed no narrowing. Additionally, two knees (4%) had severe malalignment, 17 (38%) had moderate malalignment and 26 (58%) had no malalignment, according to the study.

Allograft transplantation involved the medial compartment in 37 cases (79%) and the lateral compartment in 10 cases (21%).

In all cases, surgeons used the three tunnel technique for arthroscopic transplantation of cadaver allografts without bone block or bone plugs. They also used the articular cartilage paste grafting technique to stimulate mesenchymal stem cell proliferation, differentiation and release of growth factors, according to the study.

The postoperative rehabilitation protocol focused primarily on protecting and preserving the transplanted allograft, and secondarily on restoring range of motion.

Improved pain, function

Of the 47 transplanted allografts, 42 (89.4%) survived at last follow-up, “many of which also underwent concomitant arthroscopic debridement, cartilage treatment or stabilization as necessary,” the authors said.

Using Kaplan-Meier product analysis, time to failure averaged 52.3 months or 4.4 years. Kaplan-Meier censoring revealed a 25.3-month mean time to failure, ranging from 6.9 months to 56.7 months, according to the study.

At 5.8 years’ mean follow-up, pain, activity and function all had significantly improved from preoperatively, as follows:

pain: from 3.02 ± 0.99 to 4.06 ± 0.86 (20.8%; P=.001);
activity: from 2.16 ± 0.9 to 2.65 ± 0.92 (9.8%; P=.004); and
function: from 2.37 ± 0.82 to 3.34 ± 0.81 (19.4%; P=.001).

The researchers found no significant differences between measures of pain, activity or function in patients who did and did not have concomitant procedures, including osteotomy. This suggests that “the meniscus allograft, being the only common procedure, played a primary role in subjective score improvement,” the authors said.

Of the 47 allografts, 29 (62%) were cryopreserved and 18 (38%) were fresh-frozen, and four of the five failures occurred in cryopreserved implants. But no statistically significant correlation between failure rate and allograft material could be determined. They attributed this to the low number of failures and the high number of cryopreserved allografts, according to the study.

Also, 10 (21.3%) knees developed meniscal tears, but were successfully repaired and thus not considered failures, the authors noted.

For more information:
Stone KR, Walgenbach AW, Turek TJ, et al. Meniscus allograft survival in patients with moderate to severe unicompartmental arthritis: A 2- to 7-year follow-up. Arthroscopy. 2006;22:469-478.