Hemi resurfacing in theory appears to be an atttractive idea. However experience has proved otherwise. In a hemi resurfacing, the metal cap articulates with the natural articular cartilage of the acetabular socket. This ‘bearing” works reasonably in elderly inactive patients and fails rapidly in someone with an high activity level.
The metal on cartilage bearing is commonly use in a hemiarthroplasty of the hip which is done for femoral neck fractures in the elderly. This is probably one of the commonest procedures in orthopaedics all over the world. Elderly, sedentry patients have a high incidence of femoral neck fractures and typically they would receive a hemi arthroplasty. However if someone is a little younger and more active a hemiarthroplasty will cause destruction of the cartilage ( chondrolysis) and pain and it has to be converted to a THR. I have done many of these conversions. Therefore the world over surgeons would do a THR straight away in femoral neck fractures if the patient has a higher activity level..
Since resurfacing by definition is for younger active people, the metal on cartilage bearing is at a high chance of early failure. ( there have been some exceptions). Hence I would not use it in my practice. Some surgeons would argue that if the cartilage fails then they would convert to a total resurfacing. While the argument is valid in theory, technically a conversion of a hemi to a total resurfacing is complex..
I hope that this clarifies the issue..
with best regards.