Ｃｈａｒｎｌｅｙ式股関節全置換術の術後脱臼について

Abstract

A special review, with the aim of identifying the incidence and the factors of the dislocation of Charnley low-friction arthroplasty, was undertaken. From 1971 to 1986, 304 arthroplasties have been performed at Nagasaki University and followed over 2 years.Dislocation is defined as displacement of the head of the femoral prosthesis out of the prosthetic socket on radiography except the dislocation owing to the loosening of the socket or stem.Dislocation occurred in 8 of 304 hips (2.6%): 2 occurred during 3 weeks, 1 at 3 months, and 5 from 4 months to 180 months. Two of these were traumatic dislocations.In 5 hips, there were inadequate deepening and placement of the acetabular component at operation. In 3 hips, there were varus position of the femoral component, but those varus angles were below 5 degrees. In one hip, there was loss of neck length due to resorption of the femoral calcar. Two dislocations were related to muscle atrophy due to prolonged bedrest and other 2 dislocations were related to scarring from severe trauma or previous surgery.Only one patient showed complete bony union of the trochanteric osteotomy in dislocated cases, whereas 5 of 7 patients showed complete detachment of trochanter.Factors contributing to dislocation were inadequate orientations of prosthetic socket and loss of normal tissue tension as a result of muscle atrophy and defective bony union of trochanteric osteotomy.