REPLACEMENT OF THE ANTERIOR CRUCIATE LIGAMENT USING A DEEP-FROZEN BONE LCA-BONE ALLOGRAFT - AN EXPERIMENTAL-STUDY

One ACL in each of 17 mature sheep was replaced with a deep-frozen bon e - an ACL bone allograft. Allografts were obtained from skeletally ma ture sheep using a standard aseptic technique and stored deep frozen f or at least 6 days (mean 21 days). Macroscopical, biomechanical, and h istological changes were evaluated 12, 24, and 52 weeks following impl antation. At autopsy all allograft ligaments were present and demonstr ated no evidence of infection or immune reaction. We found slight arth rotic changes in 3 knees after 12 weeks, in 4 knees after 24 weeks, an d in 3 knees after 52 weeks. Twelve weeks after the operation the maxi mum load of the allografts was 17.5 % of the contralateral controls an d increased to 20.9 % after 24 weeks and to 32 % of controls after 52 weeks. Ligament stiffness in the linear region also increased from 18. 9 % of controls (12 weeks) to 32.5 % after 52 weeks, whereas maximum l oad decreased from 112.2 % of controls (12 weeks) to 98 % of controls (52 weeks). Histologically, the allografts progressively matured with time, becoming nearly identical to normal ligaments at 52 weeks.