The anterior cruciate ligament of twenty-five adult dogs was replaced
using fresh or deep-frozen patellar-tendon allografts. The morphology of
these transplanted allografts was then evaluated using routine histological
studies and a vascular-injection (Spalteholz) technique at various
intervals from two weeks to one year postoperatively. The fresh
patellar-tendon allografts incited a marked inflammatory and rejection
response which was characterized by perivascular cuffing and lymphocyte
invasion. Deep-frozen patellar-tendon allografts appeared to be benign
within the joint and underwent alterations that were comparable with those
observed in autogenous patellar-tendon grafts. These included avascular
necrosis followed by revascularization and cellular proliferation. At one
year, the gross and histological appearance of the patellar tendon
allograft resembled that of a normal anterior cruciate ligament.