Increased evidence: Ceramic heads recommended
The body of evidence on tribocorrosion of modular junctions in total hip arthroplasty and its subsequent effect of metal particle and ion release into the surrounding tissue was a major topic in the past two years.
Tan et al. confirmed the results from Kurtz et al. on the positive effect of ceramic femoral heads reducing tribocorrosion. The clinical effect of metal degradation products has also been demonstrated in several papers. Lash et al. presented ten cases with metal-on-polyethylene bearings with delayed dislocations associated with unrecognized adverse tissue reactions due to corrosion at the trunnion and pseudotumor formation. In a large retrospective case study, McGrory et al. showed that the soft tissue damage due to tribocorrosion advances over time. They advocate early surgical intervention and also recommend the use of ceramic femoral heads until this complication is better understood. White et al. found in their comparative study of metal vs. ceramic heads after 5 years elevated cobalt levels in 57% of the metal head group with 13% of the patients with adverse local tissue reaction. 7% of those patients have been revised already. CoP bearings were eventless.
NIH on cobalt carcinogenicity
In their 14th Report on Carcinogens, the US NIH added cobalt and cobalt compounds to their list, rating that the release of cobalt ions in vivo makes them “reasonably anticipated to be a human carcinogen”. The listing for cobalt includes different types of cobalt compounds that release ions into the body. The highest exposure to the metal occurs in the workplace and from failed surgical implants.
Less fretting with ceramic
In his presentation at SICOT 2016 in Rome, Steven Kurtz, Ph.D. highlighted the results of a retrieval study using matched cohorts of metal and ceramic femoral ball heads. He pointed out that with ceramic heads there is less material loss in head/trunnion junctions than with metal heads. He also noted that CoCr heads are responsible for more than 90% of the material loss in modular tapers and concluded that “ceramic heads are a solution for reducing taper corrosion”.
Ceramic fracture rates significantly reduced
Lee and Kim used the CeramTec database to determine fracture rates for alumina (BIOLOX®forte) and mixed-ceramic (BIOLOX®delta) femoral ball heads. Between January 2000 and December 2013, over 3.2 million BIOLOX®forte and 2.78 million BIOLOX®delta heads have been sold and implanted. During that period, 672 alumina and 28 mixed-ceramic head fractures were recorded. The fracture rate was 0.02% for BIOLOX®forte and only 0.001% for the latest generation ceramic BIOLOX®delta. 80% of the fractures occurred within 48 months after implantation.
Reliability of Mixed Ceramic BIOLOX®delta: Fracture Rates
BIOLOX®delta – a game changer?
A comparative analysis of 30,617 primary total hip implants with ceramic components from the Italian RIPO registry was recently conducted by Toni et al. It demonstrates that BIOLOX®delta components represent a significant improvement with substantially less fractures and significantly improved survivorship. The Kaplan-Meier survivorship at 8 years was 95.9% for implants with BIOLOX®forte-BIOLOX®forte bearings and 97.4% for BIOLOX®delta-BIOLOX®delta.