Twenty-seven cases with 30 hips of advanced coxarthrosis treated by valgus extension osteotomy (Bombelli) and valgus flexion osteotomy were investigated.
Clinically, arevition of pain was notable.
Roentugenologically, disappearance of bone sclerosis and pseudocyst made the trabecular structure normal. Joint space became remarkably wide and remodelled as a new joint. Some effects could be obtained as determined as a biomechanical analysis.
However, capital drop may be considered to be a new femoral head adapting to a new acetabulum, formed as the result of biological restoration. In order to promote the remodelling of the hip joint using the capital drop most efficiently, the valgus flexion osteotomy seems to be more rational than the valgus extension osteotomy.