Arthrodesis by percutaneous fixation: patellofemoral arthrodesis in rabbits without debridement of the joint.

Arthrodesis is usually performed with joint resection or at least with removal of cartilage. Our recent experience with successful fusion in all 11 rheumatoid ankles treated only with percutaneous fixation questions the necessity of debridement of the joint before arthrodesis. In this rabbit study we tested the hypothesis that joints fuse because of rigid fixation. 9 skeletally mature loop-ear dwarf female rabbits were operated on. With the knee in about 45 degrees of flexion, two 1.5 mm cortical screws were inserted through the patellofemoral joint in an anterior-posterior direction with the lag screw technique. 3 rabbits were excluded due to technical problems. Of the remaining 6 rabbits, 5 underwent bony fusion and 1 fibrous healing. Fusion was confirmed with Micro-CT in 2 cases and by histological examination in all 5 cases. In those 5 cases, bony fusion was seen in almost all areas with close contact. Therefore, fusion occurred not only in relation to the screws, but also between the screws and in the periphery of the patella. Our findings show that bony fusion can occur in a healthy joint without joint resection or debridement.