Abstract
Twelve freshly killed mature male rabbits were used to study the effects of continuous passive motion (CPM) on regional and overall nonvascular nutritional path ways of the anterior cruciate ligament (ACL). One hundred fifty microcuries of 35sulphate was injected intraarticularly into each knee joint. The right knee underwent CPM for 1 hour, while the left knee remained immobilized. Both knee joints were then isolated and immediately frozen. The ACLs were removed while still mostly frozen, and sectioned into anterior, middle, and posterior thirds for the six rabbits in Group 1, and proximal, middle, and distal thirds for the six rabbits in Group 2. In addition, quadriceps tendon samples were harvested from each limb of three rabbits. After appro priate processing, all samples were counted in a scin tillation counter, and counts per minute per milligram of tissue were calculated. There was significantly higher uptake in rest extremity ACLs compared to CPM ex tremity ACLs (P = 0.0001 ). No significant difference was demonstrated in regional uptake comparing re spective thirds of the ACL in either Group 1 or Group 2. Quadriceps tendon uptake trended higher in the limbs exposed to CPM compared to those maintained at rest (P = 0.14). The ACL uses diffusion as a primary nutrient pathway. CPM does not increase nutrient up take by the ACL in this avascular model, but CPM may facilitate transport of metabolites out of the joint. No regional differences in uptake within the ACL occurred in either group.
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