The clinical scores showed considerable variability, and this result has also been observed by others [42]. Some patients often report incomplete pain relief during the first few months after the procedure but this typically abates over time due to “accommodation” although these patients rarely become as pain free as those receiving a full replacement. When the acetabular cartilage finally wears out, pain may reappear. However, the longest survivor is a woman with SLE who is now 31 years post-op with no increase in symptoms. Although her joint space has somewhat narrowed, the patient’s UCLA hip scores remain high with 9, 7, 8, and 6 for pain, walking, function and activity, respectively. Weight appears to be related to the magnitude of pain relief, and this was observed particularly in our male patients. Our current recommendation is to reserve this procedure to lighter patients, in particular if the acetabular cartilage has already been somewhat compromised. However, the difficulty to predict the postoperative clinical scores requires that the patient understands the benefit of delaying the implantation of an artificial bearing material. Seven of our patients have been implanted with a hemiresurfacing on one side and a full resurfacing on the contralateral side. Five of these hemiresurfacing have been revised at a mean follow-up time of 59.6 months (range, 11–109) which is less than the mean 100 months of all the revised hips. A possible explanation is that the patients who can compare the hemiresurfacing side with another prosthetic joint are more likely to request a revision because the pain relief is not as good on the hemiresurfacing side.

The survivorship of hemiresurfacing does not match that of other prosthetic treatments (i.e., full resurfacing or conventional THA) but fits within acceptable ranges for a “time-buying” procedure with extremely low morbidity destined to restore the patient’s lifestyle without compromising bone stock in anticipation of an inevitable revision surgery. It was our belief that hard bearing surfaces such as cobalt-chromium or alumina would reduce the friction against the acetabular cartilage and eliminate the metallic debris possibly generated by the relatively soft titanium alloy component (our first hemiresurfacing device). Our comparative survivorship results show that femoral head material has no effect on the durability of the procedure. The advantage of the ceramic is that it can be cracked and removed without loss of bone, and full resurfacing has been successful in 2 patients for over 15 years after such revision. Unfortunately, ceramic components are not now available but would be my choice if still available. With our relatively small series, there has not been an association between survivorship gender, age, or Ficat stage, acetabular cartilage grading, component size, or patient weight, and this illustrates the difficulty to profile the ideal candidate for the procedure. We do believe that the long-term survival of some of these prostheses had to do with how precisely these implants were fitted to the acetabular cartilage in patients with relatively low activity levels.

When reoperation was needed, revision to either full surface or total hip replacement was easy and much like a primary replacement because of bone stock preservation, because of intact intramedullary canals, and because there was no debris-induced granuloma. It is important to note that a regular radiographic follow-up of the patients with hemiresurfacing devices is needed because once the acetabular cartilage is worn, a rapid migration of the femoral head through the acetabulum can occur, leading to bone loss and therefore negating one of the main advantages of hemiresurfacing. The histological response has been very benign with a few macrophages and some metallic debris scattered throughout a predominantly loose connective tissue despite significant burnishing of some titanium alloy components.

At the beginning of the series, in 1981, our indications for hemiresurfacing included patients in their 40s or even 50s or with advanced cartilage defects because there was no alternate conservative prosthetic solution available with demonstrated potential for durability. However, because of the recent success of our metal-on-metal resurfacing series for osteonecrosis [43–45], our indications for hemiresurfacing have narrowed to very young with a well-preserved joint space. We do not include heavy patients anymore, considering that the results of full hip resurfacing are excellent in this patient population [46]. In addition, hemiresurfacing components once available in 1 mm increments for optimal precision fitting to the acetabulum are now only manufactured in 2 mm increments because of cost-efficiency concerns. However, they are finished so that an acetabular component can be inserted, provided there is enough acetabular bone stock.

From our experience and that of others, we can conclude that it is unrealistic to expect a pain relief and survivorship results comparable to that of full resurfacing or conventional THA in every case. The patients who could benefit from hemiresurfacing are very young and should be fully informed and accept the “time-buying” objectives before undergoing surgery. A surprisingly long durability has been demonstrated in some patients, which may have been favored by low activity levels without participation in sports.