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Researchers find higher 5-year revision rates for THA using all-hard bearings
Metal-on-metal and ceramic-on-ceramic bearings used in one cementless hip prosthesis showed higher failure rates than metal-on-polyethylene.
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In a recently published retrospective study, researchers found high failure rates for primary cementless total hip arthroplasty when the procedures were performed with either metal-on-metal or ceramic-on-ceramic bearings.
Investigators from the United Kingdom made this conclusion following their review of National Joint Registry for England, Wales and Northern Ireland (NJR) data.
“When we looked at the commonest cementless implant — the Corail/Pinnacle implant (DePuy Synthes; Warsaw, Ind., USA) — the revision risk for the implant was significantly higher if you used a ceramic-on-ceramic (CoC) or metal-on-metal (MoM) bearing compared to metal-on-polyethylene,” Simon S. Jameson, MBBS, MRCS, told Orthopaedics Today Europe. “Metal-on-metal bearings accounted for 30% of Corail/Pinnacle hips and 28% were ceramic-on-ceramic. So almost 60% of these were implanted with hard bearings and they have significantly higher revision risks.”
High failure rates
Jameson and colleagues identified a 2.4% overall risk of total hip arthroplasty (THA) revision at 5 years among 35,386 primary THAs performed with the Corail/Pinnacle prosthesis and included in the NJR.
“In the final adjusted model, we found that the risk of revision was significantly higher in patients receiving MoM (hazard ratio (HR) 1.93, P<0.001) and CoC (HR 1.55, P=0.003) compared with the best performing bearing (metal-on-polyethylene),” Jameson and colleagues wrote.
The procedures were performed at English or Welsh public or private hospitals between 2003 and 2010 in patients with osteoarthritis who had an average age of 66 years, he noted.
Dislocation, aseptic loosening, fractures and soft tissue reactions, such as metallosis, were among the reasons for revision.
Factors that the investigators also found to increase the risk of revision were the use of the smaller Corail stems (sizes 8 to 10) and a body mass index 30 kg/m2.
“What is surprising is the commonest bearings used in this system — MoM and CoC — have the highest failure rates,” Jameson said.
The registry captured most patients in this situation because it has been routine practice to record patient arthroplasty data in the NJR, and is now mandatory in the United Kingdom, he added.
“The NJR allows you to look at what the outcome of surgery is when practiced in a general setting of the National Health Service,” Paul J. Gregg, MD, FRCS, a co-author of the study, told Orthopaedics Today Europe. “The value of the registry is it allows you to generalize what results would be for the whole population.”
Limitations and next steps
According to the investigators, the study was limited by its retrospective, observational design, medium-term follow-up and confounding factors to which they could not adjust in the study.
“For this study we did not have any radiographic information or functional data. We do not know how well unrevised patients are doing,” Jameson said.
He said as the next step in this research, the investigators plan to “compare the ‘commonest’ cemented, cementless, hybrid and resurfacing implants in different patient age groups using patient reported outcome measures, revision risks, complications, mortality and costs to determine the most cost-effective implant.” – by Renee Blisard Buddle
- Reference:
- Jameson SS. Bone Joint J. 2013; doi:10.1302/0301-620X.95B6.31378.
- For more information:
- Paul J. Gregg, MD, FRCS, can be reached at The Old Vicarage, Grinton, Richmond, North Yorks, DL116HR, United Kingdom; email: prof.gregg@binternet.com.
- Simon S. Jameson, MBBS, MRCS, can be reached at NJR, School of Medicine, Pharmacy and Health, Durham University, Queen’s Campus, University Blvd., Stockton-on-Tees TS17 6BH, United Kingdom; email: simonjameson@doctors.org.uk.
Disclosures: Gregg and Jameson have no relevant financial disclosures. The study was funded by the National Joint Registry of England, Wales and Northern Ireland.
Perspective
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Luigi Zagra, MD
This is the largest retrospective cohort study on a single-brand combination of cementless total hip arthroplasty (THA) to date. It comes from a country with a tradition of cemented implants, where in 2009 cementless THA performed exceeded cemented THA. The authors selected one type of implant from the National Joint Registry of England and Wales on which to perform appropriate statistical analysis. They found a higher revision risk in hard bearings, smaller stem sizes and body mass index 30 kg/m2. The analysis confirmed some findings: metal-on-metal had the highest failure rate, ceramic-on-ceramic showed higher revision rates while ceramic-on-polyethylene compared to metal-on-polyethylene had similar results at short- to mid-term follow-up. It is surprising 25% of patients were 60 years or younger and hard bearings were implanted in more than 57% of cases. Researchers cannot evaluate component positioning using registry data and hard bearings are more sensitive to minor malorientation in the short- to mid-term follow-up. The main reason for revision was dislocation and the fourth reason was malalignment. Small femoral canals could be unsuitable or maybe at risk for this type of cementless stem, which could be one more explanation for the higher failure.
The major limitation of the study is the short follow-up not showing differences between different types of polyethylene and not long enough follow-up for hard bearings. The correlation between bearing/implant features and the reason for revision is unknown. There was no difference in the results for head diameter, but we do not know if the smaller heads failed due to dislocation and the larger heads due to metal problems or wear. The bearing of choice and head size are open questions with no clear evidence of the best choice in the long-term.
This analysis supports the concepts that, at least with this type of implant, there is no reason to use hard bearings in older patients, attention must be paid when implanting the smaller stems, and an exhaustive informed consent should be performed when discussing indications for THA in obese patients. I agree with the authors: This study demonstrates that many factors influence the risk of revision. For long-term survival of THA, we need the right patient, the right implant and the right surgeon (correct technique, but also correct indication).
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