The effect of drill-hole length on the primary stability of osteochondral grafts in mosaicplasty.

Osteochondral grafts were transplanted from the trochlea of porcine femurs into drill holes that were 20, 15, and 12 mm in length on the lateral femoral condyle. Grafts initially were pushed in flush with the surrounding cartilage, and then a testing machine pushed the grafts 3 mm deeper. For the 20-, 15-, and 12-mm drill holes, mean forces for pushing the graft flush were 36.58, 43.33, and 118.13 N, respectively, while mean forces for pushing the graft 3 mm deeper were 122.50, 249.33, and 377.25 N, respectively. These results suggest primary stability is better when grafts and drill holes are the same length, but if the recipient hole is shorter, excessive force must be exerted on the cartilage cup during insertion.