[An arthroscopic study of coxarthrosis].

Arthroscopy was performed on 110 hips with coxarthrosis secondary to hip dysplasia. The cartilage degeneration was then classified arthroscopically and the findings compared with radiographs. The patients ranged in age from 16 to 52 years old (mean 28.1 years). The cartilage degeneration by arthroscopy was classified as follows; Type 0: normal cartilage, Type I: irregular, Type II: fibrillation (a: membranous type, b: featherlike type, c: edematous type, or d: short type), Type III: erosion, Type IV: eburnation. The cartilage degeneration varied from Type 0 to Type IV corresponding with the stage on plain radiographs. The patients were divided into two groups: Group 1: less than 30 years old (64 hips), Group 2; 30 years old and older (46 hips). Group 1: consisted of 32 cases with the degeneration in the acetabular cartilage more severe than in the femoral cartilage, 16 cases with the degeneration in the femoral and acetabular cartilages of the same severity, and the other 16 cases with the degeneration in the femoral cartilage more severe than in the acetabular cartilage. Degeneration of the acetabular cartilage was more severe in cases with a CE angle less 10 degrees, with incongruence on plain radiographs or with thin cartilage on the arthrogram. Group 2 consisted of 20 cases with the degeneration in the femoral cartilage more severe than in the acetabular cartilage, 14 cases with the degeneration in the femoral and acetabular cartilage of the same severity and 12 cases with the degeneration in the acetabular cartilage more severe than in the femoral cartilage. Degeneration in the femoral head was more severe in cases with the CE angle was less than 10 degrees, with incongruence on the radiogram, or with thin cartilage on the arthrogram. In comparison with arthrography, we observed a marked fibrillation at the lateral margin of the acetabulum in most cases in which the labrum was torn. From this study, we conclude that the initial degeneration occurs in the acetabular cartilage, with degeneration in the femoral head occurring later.