Modern Hip Resurfacing
In other words, the implants were not allowing for the bone of the pelvis to grow into the outer surface of the implant and create the biologic bond that traditionally occurs after hip replacement surgery. These large, fluid-filled cysts grow around the implant and require prompt surgical removal.
Although these three types of implants have been recalled, that does not mean that there are no options for patients who require a hip replacement; the Smith and Nephew Birmingham Hip Resurfacing System has not fallen prey to the recalls and remains a viable option for younger, male patients. Rosen recommends the use of a ceramic femoral head with a titanium acetabular shell and a highly cross-linked polyethylene liner between the ball and socket for his patients.
This has been shown to be one of the most effective, most used hip replacements on the market today. If patients who have received a metal-on-metal hip implant begin to experience pain, Dr. The success of hydrodynamic lubrication in resurfacing is heavily dependent on the precision of the manufacturing process. In vivo articulation appears to be a combination of hydrodynamic lubrication with episodes of more conventional friction, and the suggestion that hip resurfacing is associated with zero wear is probably fanciful.
In comparison to metal on plastic hip replacements, metal on metal hip resurfacing produces a much lower volume of debris. It does, however, produce a very fine cobalt chrome debris. Some studies suggest that over a million such particles are generated with every step. As in metal on plastic total hip replacements, metal particles generated at the hip have been found as far away as the liver and spleen in postmortem studies. The large surface areas generating this fine metallic powder increase the level of cobalt chrome ions in the blood.
Back et al 34 looked at serum cobalt and chromium levels after modern hip resurfacing and their effect on renal function. A similar pattern was observed with chromium, which peaked at 9 months. There was no adverse effect on renal function. Given the age group that might be treated with hip resurfacing, it has been suggested that circulating cobalt chrome ions may represent a teratogenic risk to younger women.
History of resurfacing
Brodner et al 35 analysed the ion levels in blood taken from the placenta of three pregnant women who had previously been treated with metal on metal hip replacements. These were then compared with the maternal serum levels. This study shows that at term, cobalt chrome ions do not cross the placental barrier.
The tumours that have been identified may simply represent randomly located neoplasms that have occurred adjacent to a prosthesis. The femoral head remnant may undergo avascular necrosis AVN after hip resurfacing. If this does occur, then AVN might have a role in subsequent failure of the prosthesis.
In a large retrieval study in , Howie et al 37 looked at 72 femoral heads that had been treated initially by resurfacing and found only limited evidence of AVN. A correlation between component loosening and histological evidence of AVN could not be found in this study. Similar results were reported by Bradley et al in More recently, Little et al 25 reviewed a series of hip resurfacings that required 13 revision procedures.
Histological examination of the retrieved femoral remnant showed evidence of osteonecrosis in all but one specimen. None of these cases had shown histological evidence of osteonecrosis in the femoral bone at the time of the initial implantation. The conceptual advantages of hip resurfacing are now well recognised and by the end of most prosthesis manufacturers had introduced their own metal on metal hip resurfacing. This debate also touches on the conservative instincts of the British orthopaedic community and forces us to confront one of the fundamental dilemmas of all medical research.
If we deliberately confine ourselves to those treatments in which there is an existing collective confidence, we will effectively freeze our technology at its current level. Conversely, if we experiment with new technologies in orthopaedics which are subsequently found to have failed, we may expose patients to unnecessary revision surgery. Hip resurfacing is a technically different procedure from conventional hip replacement.
A patient requesting a resurfacing should be referred to a surgeon with an established interest in hip resurfacing. The British National Health Service is now tending towards a policy of fixed price arthroplasty and this policy may create pressure to use cheaper hip implants. But these are difficult figures to interpret.
The true total cost of any hip replacement is hard to establish. In Britain, the National Institute for Clinical Excellence recommends that hip resurfacing be regarded as a separate technology from ordinary hip replacements. The National Institute for Clinical Excellence also recommends that resurfacing be contraindicated in anyone deemed to be at risk of osteoporotic fracture. National Center for Biotechnology Information , U. Journal List Postgrad Med J v. Steven Cutts and Paul B Carter.
Author information Article notes Copyright and License information Disclaimer. Accepted Mar This article has been cited by other articles in PMC.
Abstract In recent years there has been a resurgence of interest in the concept of hip resurfacing. History of resurfacing The actual concept of hip resurfacing arose quite early in the history of modern hip surgery.
Modern Hip Resurfacing
Modern hip resurfacing British leadership in this speciality owes much to the work of Derrick McMinn, an orthopaedic surgeon based in the West Midlands with a long track record of technical innovation. Infection There is little reason to suppose that hip resurfacing infection rates will differ from those associated with total hip replacement. Dislocation It seems intuitively obvious that a large femoral head will be associated with a lower risk of dislocation, and evidence has emerged in the literature to support this view.
Pulmonary embolism A conventional hip replacement involves the penetration of the proximal femoral canal by large reamers and in most cases by pressurised, liquid cement. Fractured neck of femur Fractured neck of femur is a recognised complication of hip resurfacing that has no obvious parallel in modern conventional stemmed hip replacements. Open in a separate window. Stress shielding One matter of concern in conventional hip replacement is loss of femoral bone stock owing to stress shielding.
Tribology and plasma ion levels Tribology is a branch of engineering that deals with wear and friction between moving surfaces.
Hip resurfacing: a technology reborn
When wear does occur, it generates many fine particles of metal known as debris. Teratogenicity Given the age group that might be treated with hip resurfacing, it has been suggested that circulating cobalt chrome ions may represent a teratogenic risk to younger women. Avascular necrosis The femoral head remnant may undergo avascular necrosis AVN after hip resurfacing.
Conclusions The conceptual advantages of hip resurfacing are now well recognised and by the end of most prosthesis manufacturers had introduced their own metal on metal hip resurfacing. Evolution and future of surface replacement of the hip. A multitude of important pointers are provided for patient positioning and exposure.
Particularly noteworthy were exposure of the sciatic nerve in patient with DDH and the Ranawat recommendation of division of the tendon of the gluteus maximus to avoid pinching of the sciatic nerve during leg rotation. Common pitfalls in acetabular preparation and insertion of a standard BHR cup are discussed and tips to avoid these outlined. Some photographs in this section could have done with a little more clarity and close-up. Implantation of the femoral component of the BHR is described in superb detail and gives the most noteworthy account of the technique and likely complications to arise, discussed.
The evidence for the recovery room x-ray though, is not convincing enough. Birmingham Mid-Head Resection BMHR prosthesis is described in lurid detail and is particularly helpful if purely for information for the trainee or the new consultant alike.
- Cinderella of Harley Street (Mills & Boon Medical).
- Moms Story?
- News archive.
- Whos That Walking?;
- A Decade of Modern Hip Resurfacing.
- Advances in Applied Mechanics.
Outcomes and Standards for hip resurfacing authored by none other than Paul Pynsent, the golden boy for statistical research and analysis at the Royal Orthopaedic Hospital is short, succinct and delivers the driest of information in a presentable and easy-to-digest format. Perhaps one of the most important chapters is the results of BHR in different diagnoses like the young arthritic, AVN, inflammatory arthritis, post-septic arthritis and childhood disorders.
Modern Hip Resurfacing - Orthopaedic Product News
This makes absolutely fascinating reading and gives the reader of the likely success rates and may help in pre-operative counselling. As regarding complications and revisions the author makes a point about the majority of failures needing revision to a total hip replacement which would have been a treatment option for the original disease anyway in absence of hip resurfacing. In concluding paragraphs Derek McMinn alludes to and pays homage to Charley Townley who was his inspiration and whose surgical outcomes were a forerunner for the current state of resurfacing hip arthroplasty.