[Effectiveness of intra-articular application of hyaluronic acid on early forms of femoropatellar arthrosis--an experimental study in dogs].

Purpose: We investigated the effects of intraarticularly applied hyaluronic acid on the cartilage-integrity with early-forms of retropatellar cartilage degeneration (chondromalacia patellae) in dogs.

Methods: We used the Pond-Nuki model (tenotomy and resection of the anterior cruciate ligament = ACL) in 27 dogs (foxhounds) (3 groups of 9 animals) PILOT STUDY: ACL-tenotomy and resection, no therapy, specimens retrieval after 3, 6, 12 weeks (3 animals each period). VERUM: ACL-tenotomy and resection, hyaluronic acid (start after 3, 6, 12 weeks), 5 injections in 4 weeks, specimens retrieval after 5 weeks following final injection (12, 15, 21 weeks postoperatively, 3 dogs each period). PLACEBO: same procedure as verum, but saline-injections. Specimens were taken from the medial/lateral patellar pole from both, the operated and the normal knee and examined histologically using various staining methods (HE, Azan, Toluidin, Masson-Goldner, Safranin-O). A modified Mankin score was used to grade cartilage degeneration.

Results: Our results demonstrate that the Pond-Nuki model is suitable to experimentally induce chondromalacia patellae. There were significantly less degenerative cartilage changes in the knees treated with hyaluronic acid compared to the placebo-group.

Conclusion: Our results let assume that hyaluronic acid could be indicated i.e. after arthroscopically diagnosed early cartilage-degeneration, the final conclusions concerning the actual mechanisms and therapeutical effectiveness need however further prospective clinical and experimental investigations.