In opposition to standard total hip prostheses, hip resurfacing replaces the diseased surfaces only; the femoral head and femoral neck stay preserved. The femoral head is “crowned” with a metal cap and a thin-walled acetabular cup. The material consists of a special cobalt-chrome-molybdenum alloy with high carbon content for decreased wear.
Besides the advantages of bone preservation and tissue protection, this implant is very suitable for young and young at heart patients, who actively participate in life, but are impaired in their private and/or professional activities, due to their hip joint disease. The pain is particularly essential here, as well as the restriction of movement. However, stable bone conditions, especially in the head and neck area of the femur, are indispensable for performing the resurfacing.
Advantages of hip resurfacing over standard prostheses:
- The implant imitates the natural size of a human hip joint and allows in this way a natural degree of mobility and higher safety, concerning the danger of dislocation.
- The joint sensibility and reflexes are preserved.
- No changes in leg length and leverage of hip muscles take place.
- The natural force transmission from the pelvis to the femoral head and femur does not lead to change in bone structure or bone loss, but increases bone density.
- The proximal femur is preserved to provide very good conditions for all kinds of prosthesis shafts, in case of revision surgery
In most cases, a quicker recovery is possible, if compared to standard procedures. Experience shows that it is easier to return to private and professional activities, including sport. The abrasion resistance resulting from lubricated friction and the very low risk of dislocation mean for the patients that they can go for such types of sports, where conventional prostheses cannot be recommended. This also holds true for professions, which practice with a standard prosthesis is impossible or risky.
The general statements, however, cannot be made: it is recommended that you have a detailed medical consultation, in order to clarify for you individually, if tennis, skiing, Judo or professional dancing are really possible for you after the surgical intervention.
The idea of BHR prosthesis, to cover the surface of the femoral head only, is not new: the implementation trials started in the 1970s and 1980s, but could not establish itself due to the lack of money. So the medical research focused predominantly on further development of standard procedures and improvement of implant materials.
Derek McMinn, surgeon in Birmingham / Great Britain, finally rediscovered succesful material of the past in 1989 and took up again the idea of resurfacing. In studies the load-bearing capacity of the implant has been examined in detail and in 1997 it was introduced as the first modern hip resurfacing implant.
For over 20 years and with more than 170.000 patients, the original implants after McMinn (Birmingham hip resurfacing) have achieved excellent results that have been confirmed through numerous scientific publications. Meanwhile, other prostheses developer and manufacturer have also discovered hip resurfacing and offer the corresponding implants in different composition of matter and designs. Meanwhile many of the new developments are already withdrawn from the market because of bad results. It is necessary as it is with any new implant to test them in clinical studies. How durable are they and how functional . Helpful are the registries. They show best results with the BHR (Birmingham hip resurfacing), and ADEPT implants. Actually hip resurfacing was developed to buy some years for younger patients before they have to get total hips. Today resurfacing is competing in durability with all other implants. In many cases we see outstanding results and advantages compared to the outcome of total hips. These advantages of HRA could and do help even in extreme sports. Newest example: Andy Murray, professional Tennis-player.
LINKS / STUDIES:
Hip Int. Hip resurfacing: history, current status, and future.
“Hip resurfacing arthroplasty (HRA) presents several advantages over conventional total hip arthroplasty (THA), including conservation and preservation of bone, reduced risk of dislocation, easy replication of hip biomechanics and easy revision if needed. It is a particularly appealing procedure for young patients. HRA has been performed for over 40 years following the same technological advances as THA. The bearing material used by most designs is metal-on-metal (MoM), which has the best compromise between strength and wear properties. However, MoM HRA has a specific set of possible complications. Aseptic femoral failures were initially the most prevalent cause for revision but progress in patient selection and surgical technique seem to have resolved this problem. Wear-related failures (high metal ion levels and adverse local tissue reactions) are now the main concern, and are essentially associated with poor acetabular component design and orientation, to which MoM is more sensitive than other bearing materials. The concept of functional coverage is key to understanding how MoM bearings are affected by edge wear. Only a 3-D assessment of cup position (e.g., the contact patch to rim distance) provides the necessary information to determine the role of cup positioning in relationship with abnormal bearing wear.The concept of hip resurfacing is more valid today than ever as the age of the patients in need of hip arthroplasty keeps getting lower. The recent publication of several excellent long-term survivorship results suggests that selection of a well-designed resurfacing system and accuracy in the placement of the cup can achieve long-term durability.”
Another study from 2017:
Registry data 2018:
National-hip-registries-2018 National hip registries have demonstrated good to excellent, medium to long-term survivorship results with certain HRA designs such as the Birmingham Hip Resurfacing.
Metal ions / Cobalt 2019: https://www.germanjournalsportsmedicine.com/archiv/archiv-2019/issue-5/editorial-sauerstoff-und-leistung/ Similar to hypoxic conditions, cobalt stabilizes hypoxia-inducible factor α (HIFα), leading to increased endogenous production of erythropoietin. Since the World Anti-Doping Agency (WADA) suspects that cobalt is being used for doping purposes for this reason, it was put on the list of prohibited substances in 2015. At present, cobalt is included in many nutritional supplements advertised as “performance boosters” and is often not declared or mislabeled. Schmidt et al. explain the erythropoietic effects of low dose cobalt and the possibility of detecting abuse. Their request to WADA is to establish limits for cobalt in the urine and blood and to perform systematic tests.
Link for RECERF