I use Biolox Delta ceramic heads in nearly all of my hip replacements. This summary of their performance is very reassuring! In short, Delta ceramic is highly unlikely to break – I have never seen it happen in my patients. I am hoping to be able to use ceramic resurfacing next year in selected patients – watch this space!
Historically there have been considerable reservations in using ceramic femoral heads in total hip arthroplasty because of concerns regarding trunnionosis, limited head and neck length options as well as the risk of implant fracture. However, with manufacture and design improvements addressing these concerns, ceramic heads are now used in up to 50% of implanted femurs.Perceived benefits of using ceramic femoral heads on highly cross-linked polyethylene include improved wear rates, and reduced risk of corrosion and fretting at the head–trunnion interface. However, there are some in the orthopaedic community who continue to be concerned regarding the risk of fracture, although all previous studies that have attempted to address this issue are single-centre reports with relatively small numbers. This study from Philadelphia, Pennsylvania (USA)1 is extremely helpful as it reports the outcomes of around six million patients. The authors’ aim was to determine the fracture rate of modern alumina-pure alumina (PA)- and alumina matrix composite (AMC/Biolox delta) ceramic heads, and to identify the factors which may influence fractures. The authors used the manufacturer’s own database, which was the result of a directive from the regulators requiring the reporting of device-related adverse events. As CeramTec (Plochingen, Germany) provide over 90% of all ceramic components to major orthopaedic suppliers, this is a comprehensive, if potentially biased, study. Between 1 January 2000 and 31 December 2013, over 3.2 million PA and 2.78 million AMC femoral heads were implanted. During this period there were 672 PA femoral head fractures (0.0201% or 1 in 5000) compared with 28 AMC head fractures (0.0010% or 1 in 100 000). In addition, since the year 2000 the number of reported fractures has decreased. The fractures tended to occur at an early stage following implantation, with 80% of the PA heads occurring within 48 months and 90% within 72 months. Fractures tended to occur following trauma, hip dislocations and component malposition, although the data on this issue were not comprehensive. In addition, the authors highlight that smaller-diameter PA heads were more likely to fracture, compared with larger heads (28 mm vs 32 mm). There were no reported fractures in heads of 40 mm in size. A short-taper 28 mm PA head was more likely to fracture when compared with any other 28 mm heads on any other taper. The authors demonstrated that taper designs and mismatch was the principal cause for fracture attributed to the majority of the AMC heads, and taper debris or contamination was often found in the PA head fractures. While there are drawbacks to this study design, with suggested under-reporting to the manufacturer of ceramic fractures, the lessons learned from those heads that did fracture remain valid. This study is the largest reported to date on ceramic femoral head fractures over a 15-year period and I would commend all hip surgeons to review its findings, particularly when most manufacturers will provide ceramic heads at no additional cost, albeit the PA variety!
Tags: arthritis, hip replacement, hip reserach, hip surgery, Metal hips, retrieval analysis