Anterior cruciate ligament fascia lata allograft reconstruction: Progressive histologic changes toward maturity

Biopsy samples were obtained arthroscopically from 21 patients who had undergone anterior cruciate ligament (ACL) reconstruction using rolled, freeze-dried fascia lata allograft in order to evaluate progressive histologic changes toward maturation. The study period was 3-20 months postoperation. The mean age (+/- SEM) was 31.9 +/- 10.3. Histomorphometry was used for quantitative evaluation. Arthroscopic examination showed fully synovialized allografts in all patients. Varying degrees of degenerative tissues were observed histologically. There was a significant, direct correlation between the percentage of polarized tissue and the maturity of the biopsy specimen (r = 0.9; p < 0.04). The mean area of polarization in the postrehabilitation period (10-20 months) was significantly higher (p < 0.01) than in the rehabilitation period (3-20 months). Overall, there was a progressive decrease in cellularity and vascularity as the allograft matured. Compared with the biopsy samples of normal ACLs, the allograft was still undergoing maturation 20 months postoperatively.