Meniscal allograft transplantation. Two- to eight-year results

We evaluated 18 of 23 patients who had undergone cryopreserved meniscal allograft transplantation for compartmental pain after total meniscectomy 2 to 8 years (mean, 5.4) after the operation. The Short Form-36 scores revealed a decrease in pain with a significant improvement in function, although function remained limited. There was no significant decrease in joint space on 45 degrees posteroanterior weightbearing radiographs through the duration of the study. Eight of 22 allograft menisci (36%) tore during the study period, necessitating 6 partial and 2 total meniscectomies. Two patients subsequently underwent reimplantation. Histologic examination of the removed tissue revealed reduced cellularity as compared with normal or torn native menisci. Four specimens also underwent detailed cytokine evaluation and demonstrated reduced cytokine expression compared with controls. While successful in alleviating compartmental pain that may be a late consequence of major meniscectomy, allograft menisci are repopulated with fewer cells than are present in normal or torn native menisci. These cells also demonstrate potentially reduced function, as measured by decreased growth factor production. This decreased biologic activity may be a factor that contributes to the high frequency of retears noted in this and prior studies.