This is a more bone conserving technique. This procedure involves removal of just the damaged bone surface and capping it with metal head. Hence, unlike in the standard hip replacements the head and neck of femur are not removed. Also since this procedure only caps the surface of the head, the effective size of the ball is nearly same as the normal head. The potential benefits with this design are:

• Better range of movement
• Decreased incidence of dislocation
• If and when it fails, the revision would be easier since the bone of the upper femur is retained

However, on the other side there is not enough long-term data as compared to the standard hip replacements. The longest follow-ups reported are just about a decade, unlike 20-25 years follow-up data available for the standard hip replacement. Also this procedure is not suitable for all cases, and proper case selection is mandatory.

25 year old lady crippled by painful chodrolysis of the left hip joint. Treated with surface replacement of the hip. This procedure involves very minimal bone removal.