In the last 10 years, total prosthetic replacement has become the hip oper­ ation for many but not all surgeons. In our clinic the increasing frequency of TP has been paralleled by a reduction in the frequency of 10 and HA. For the experienced orthopaedic surgeon and hip surgeon, hip disease has so many facets that it could not possibly be tackled with one operation alone. Thus, HA seems recently to have won renewed recognition. It has once more become the procedure of choice in specific cases, possibly because of certain disadvantages and complications associated with TP which have somewhat tempered the original optimism. Currently, the risk of infection or loosening of the pros thesis is such that the operation cannot justifiably be recommended for patients under 55-60 years of age. In contrast with HA, in the majority of cases the results of TP or 10 are not fully predictable. The loss of joint motion is offset by two important advantages: -complete freedom from pain - full weight bearing is possible on the arthrodesed hip. On following up our HA operations from 1961 to 1971, we examined the development of the operative procedures in our clinic. We found that the range of indications had narrowed as stricter criteria were applied in choosing patients for operation. Adequate and precise operative tech­ niques were developed. We studied the biomechanics of the hip joint exten­ sively (effect of arthrodesis on the statics and dynamics of the hip joint and neighbouring joints).