Budapest Revision Hip Symposium, November 2007

The International Symposium On Revision Hip Arthroplasty – 28-30 November 2007

I was invited as a faculty member to speak at The International Symposium On Revision Hip Arthroplasty where I gave two presentations. The venue – Intercontinental Budapest – is situated next to the Chain Bridge and overlooks the Danube and has a glorious view of the Royal Palace.

The meeting was chaired by Adolph Lombardi (Joint Implant Surgeons Inc, The Ohio State University, Mount Carmel Health System, New Albany, Ohio) and co-chaired by Marci Maheson (University Hospital of Wales, Cardiff). The European and American perspective about the issues pertaining to hip arthroplasty were voiced. The speakers addressed the political, demographic and financial problems facing the surgeon and the impact on patients. In the United Kingdom quantity not quality, cost not efficacy was felt to be the political order of the day. It was noted that there is an increased revision rate in patients in the United Kingdom, Europe and America. At the same time patients are demanding an improved quality of life, are younger and more active. The world population is increasing and by 2030 it is predicted that there will be a 175% increase in total hip replacements in the United States. It was noted that there would be fewer residents and fellows available to meet the needs of the expansion of total joint replacements.

I presented on Perspectives in Hip Replacements and identified the changes in hip prosthetic design over the last five decades. There is evidence of a trend towards the use of cementless total hip replacements from cemented hip replacements as documented in the National Joint Registry (UK). Historically most surgeons would utilise a single type of cemented hip replacement, however with acceleration in technology there is now a vast number of prostheses from which the surgeon can choose to suit their patient.

There is also a selection of bearing surfaces available to surgeons. It was noted that the bearing surfaces are the prime issue and that the wear rates vary considerably from a low wearing ceramic on ceramic bearing surface to a bearing surface using standard polyethylene (plastic) on a metal head. There has been a breakthrough with the 3rd generation polyethylene which is stabilised with vitamin E. The new plastic shows a dramatic reduction in wear. These bearing surfaces as well as metal on metal bearing surfaces can now accommodate big head technology which allows for a reduction in dislocation and an increased range of hip movement. I commented that the influence of 'stubbies’ and porous metals is likely to have a huge impact on surgical practice in the future. I noted that today’s patient differs from the original cohort of patients 30 years ago!

A rapid fire session was conducted by the chairman where members of the faculty provided their answers to vexed issues so that the delegates could have their problems aired by the expert panel which included myself, Tom Donaldson, Eric De Witte, Roger Emerson, Christian Götze, Otmar Hersche, Ed McPherson and Jens Stürup (Rigshospitalet, Denmark). Pierre-Luc Fresard joined the panel when the session continued on Thursday morning. This type of questioning under intense pressure was enthusiastically received by the delegates. I thoroughly enjoyed being cross examined by Adolph Lombardi.

In my second presentation I spoke on the technical challenges of how to manage complex problems in hip replacements. In essence the primary aim of surgery is to relieve pain and restore function. One also tries to provide the patient with a joint replacement which will last. The types of surgery available to patients are fusion of the hip (arthrodesis), to perform procedures which reposition bone around the hip joint (osteotomy) or provide the patient with a hip replacement. I light-heartedly described the acetabular socket as the ‘awkward acetabulum’ and the femoral surgery as the ‘fiddly femur’. I described the technique of osteotomies and hip replacement in complex hip surgery and showed examples of these pre and post operative results.

Erik De Witte (Algemeen Stedelijk Ziekenhuis, campus Aalst, Belgium) discussed the anterior supine intermuscular approach, a form of minimal invasive surgery. He discussed the history and use of this direct anterior approach to the hip joint. Otmar Hersche (Schulthess Klinik, Zurich) cautioned the delegates about the complications following small incisions with minimal access to the hip joint.

The question was asked by Roger Emerson (Center For Joint Replacement, Plano, Texas) ‘How Short Can We Go?’. Standard length porous ingrowth femoral stems have been designed to gain stability but noted that it would be beneficial to be less invasive with a shorter stem or ‘stubbies’ as they are known. The distal part of the stem does not play a major role in stability. Stubbies are able to compete with the resurfacing arthroplasty concept and are also less arduous to revise.

Implant failure is related to wear debris from the bearing surfaces and associated osteolysis as well as pain, instability and recurrent dislocation.

Tony Ward dealt with the problems performing total hip arthroplasty after fractures of the acetabular socket and femur. He also discussed the problems using acetabular cages and highlighted the strategies when the socket is disrupted (pelvic discontinuity).

The delegates learned how to avoid dislocation following total hip arthroplasty by anatomical orientation of the components while at the same time restoring offset and leg lengths. Dislocation has been reduced by slimmer neck designs, elevated or constrained liners and the utilisation of larger ball head sizes. It was noted that big head technology had improved hip joint stability.

Christian Götze (University of Münster, Münster) and Pierre-Luc Fresard (Hôpital Marrel, France) continued the theme of dislocation and described a double mobility cup which comes as a cemented or cementless model. The polyethylene liner is mobile within the outer shell and the femoral head then articulates against the mobile liner. The results with this design cup have been excellent. The double mobility cup is predominantly used in France and to a lesser extent in other European countries.

When all else fails an alternative approach is to use a constrained acetabular cup, of which there are numerous examples from various orthopaedic manufacturers. Besides hip instability, constrained cups can be used in patients with neurogenic disease. A meticulous soft tissue repair was emphasised as a prevention of dislocation, which remains a difficult problem in hip surgery.

The curse of joint replacement surgery – infection – was brought to the attention of the delegates. Ian Stockley highlighted that every surgical intervention was a risk for the patient and that prophylaxis was paramount. Laminar flow operating theatres reduce the infection rate and to a lesser extent so do body exhaust suits. The rates of infection directly relate to airborne bacteria. The problems facing the revision hip surgeon are damage to soft tissue, impaired blood supply, bone defects and extended duration of this difficult type of surgery. It was noted that the technique of addition of antibiotics to the operative site in bone cement was essential in the management of an infected hip arthroplasty.

Ed McPherson (LA Orthopaedic Institute, Los Angeles, California) provided the delegates with further insight on this subject. Joint infection evokes frustration and is a devastating complication for the patient. A biofilm on the implant is the cause of the chronic infection process and the ultimate aim is prevention of any infection. The pathomechanics relate to shedding of the organisms in the operating theatre and wound care. Wound debridement, the strategic use of antibiotics and operating room discipline are the cornerstones of treatment of infection of the hip joint.

The infected hip could be dealt with in a one stage exchange as described by Thorsten Gehrke (ENDO-Klinik, Germany) and the concept was also to obtain a high level of concentration of antimicrobial agents at the site of infection. The treatment could also be performed in two stages with radical debridement and removal of the prosthesis prior to returning to perform reimplantation of a hip prosthesis at a later date. In the interim period the use of an antibiotic hip spacer allows the patient to partial weight bear while at the same time delivering high local concentrations of antibiotics. Overall the results have shown improved outcomes with a two stage exchange, though it should be noted that one stage exchange may have similar results in the hands of orthopaedic surgeons with a highly specialised interest in infected joint replacements as at the ENDO-Klinik.

The timing of the exchange of a worn polyethylene liner was evaluated and it was noted that if the operation occurred too early the risks of surgery were not worth the clinical benefits, but that if left too late there would be a need for component revision and this would usually be associated with bone loss (osteolysis). It was felt that regular follow-up was required. If acetabular shells were stable then local osteolytic areas could be bone grafted and the bearing surfaces exchanged to low wear third generation cross linked polyethylene (E-poly).

Tom Donaldson (Loma Linda University, Loma Linda, California) identified the need to create a stable acetabulum/pelvis, restore bone stock and regain the anatomical hip centre. The use of jumbo cups was discussed and they were felt to be an advance over the use of cages and rings particularly in severe acetabular defects. A custom triflange cup was noted to be extremely successful when there was little support bone.

Porous metals offer a significant advantage and it is possible that it will provide patients with improved fixation and long term stability in the future. Acetabular cups made from porous metal. Trabecular metal revision shells with or without augments have revolutionised revision surgery for acetabular defects. The initial results have been encouraging and as yet there is no evidence of cup migration. Porous metal enhances initial stability and encourages bone cell adhesion and allows for reliable bone ingrowth. It is possible that porous metal acetabular components will become the gold standard for complex revision hip surgery.

Impaction allografting was discussed by Peter McLardy-Smith using cemented components in extensive femoral bone defects. The technique was performed with the Oxford Hip Prosthesis. I noted that this technique, as well as impaction allografting with a cementless femoral component, is technique dependent and therefore good outcomes would be less likely with an occasional impaction grafting surgeon.

Periprosthetic femoral fractures have become an increasing problem, particularly in the aged patient, in pathological fractures, as well as in prosthetic loosening. Intra-operative problems are also an important cause of periprosthetic fractures. Michael Wagner identified the different surgical techniques to deal with this problem and noted that treatment with metal plates were the cause of the highest complications. He also identified the risks of distal femoral bone atrophy and noted that such cases may require a total femur replacement. Such orthopaedic cases are always demanding and the operation should allow the patient to mobilise full weight bearing. Self locking conical revision stems with cutting flutes showed early osseointegration and the promotion of even bone loading when used for periprosthetic fractures.

When proximal bone stock is inadequate for prosthetic support a Calcar replacement femoral component is required. These stem designs have demonstrated a varied mid to long term survivorship, often dependent on how far the ‘envelope is stretched’. Modular revision prostheses have provided the surgeon with further options in difficult cases.

Total femur replacements or customised prostheses may be required where patients require limb salvage. Such surgery is extreme but it was noted that most patients have reduced pain and greater mobility following total femur replacements.

Members of the faculty were asked to present a surgically difficult revision hip problem and discuss the options in each case.

The surgeons (myself included) enjoyed the venue and the Chairman, Adolph Lombardi was delighted with the wide variety of views presented by the faculty as well as the interactive response by the delegates.

Sponsor: Biomet Inc. and support by Boehringer Ingelheim