BOA Statement on Component Combinations in Hip Replacement Surgery

Joint replacement has become the commonest major surgical procedure carried out in the developed world. Artificial joints are the most cost efficient and effective treatment available for patients with significant arthritis allowing them to regain mobility and almost eliminate their arthritic pain.

The technology and design of implants have advanced considerably over the years with significant success. However, the combination of increasing complexity and expectation (we now expect 95% of all implants to last at least 10 years without problem) has created a situation where even apparently minor differences in design, materials used or implant finish can cause untoward problems.

Some of the best results in joint registries (national collections of information about the performance of joint replacements) are obtained using components from different manufacturers to achieve optimum results. However as technology advances it can prove difficult to ensure that specific combinations are compatible, even from the same supplier.

While some components match extremely well it has become clear that more modern cutting edge technologies can create critical combinations which have produced new problems, most notably, but not exclusively, metal surfaces which move very slightly. Very minor design or material differences have created unexpected clashes magnified by the extreme use we expect from our joints.

Orthopaedic surgeons have been aware of the issues relating to design and material mismatch such that the numbers of problematic combinations has reduced rapidly following the relatively early detection of problems with large head stemmed metal – metal hip replacement. 

We would like to take this opportunity to remind our colleagues of increasing concern about the critical nature of some combinations, particularly related to the taper on the femoral component of hip replacements (connecting the head to the stem of the implant into the thigh bone). However the widespread use of well tested, evidence based combinations from different companies (and some crossover combinations from the same company) has resulted in excellent results for our patients as evidenced from the largest studies worldwide into the long term results of any medical treatment.

We must all remain vigilant and continue our unusual, yet highly successful, co-operation between industry, the profession and government through the National Joint Registry to ensure that our patients continue to receive the best most durable combination to enable them to mobilise without pain for the rest of their life.