Cemented hip arthroplasty implants found more effective than MoM implants

Issue: January 2016

Antibiotic-impregnated cemented total hip replacement has a better prognosis after 33-month follow-up than metal-on-metal hip replacements, according to results of a recently published population-based study.

Characteristics of total hip replacement (THR) are related to early implant revision and survivorship, according to Mahmoud Zureik, MD, PhD, the lead investigator of the study.

“These findings about short-term prosthetic survivorship are useful in helping surgeons select a THR fixation technique and bearing surface, especially for elder patients who have a short life expectancy,” Zureik told Orthopaedics Today Europe.

Zureik and colleagues compared three types of fixation — antibiotic-free cemented THR, antibiotic-impregnated cemented THR and uncemented THR — in 100,191 patients with data in a French national health insurance database. They also compared the THRs according to bearing type, which were ceramic-on-ceramic (CoC), ceramic-on-polyethylene (CoP), metal-on-metal (MoM) and metal-on-polyethylene (MoP).

THR survivorship

The cohort included patients aged 40 years and older who underwent THR from April 1, 2010 to Dec. 31, 2011 for arthritis, according to information in the database.

Zureik and colleagues assessed survivorship by cement type and bearing surface using a univariate and multivariate Cox proportional hazard regression model adjusted for patient and implant characteristics. All revisions, including any surgical interventions in which the implant or any of its components were changed or removed, were noted.

“The existence of an association between the fixation technique and/or bearing surface and prosthetic survivorship has yet to be established. The main aim of our work was therefore to compare THR short-term survivorship according to cement type and bearing surface in a large population of subjects who have undergone THR for reasons other than trauma and bone tumor, taking prosthetic revision risk factors (age, gender, comorbidities, concomitant medication, implanting center, etc.) into account,” Zureik said.

Revision risk

Among the patients studied, 74.8% received an uncemented THR, 3.8% received an antibiotic-impregnated cemented THR and 21.4% received an antibiotic-free cemented THR. In addition, 40.9% of patients received a CoC bearing, 33.9% of patients received a MoP bearing, 20.8% of patients received a CoP bearing and 4.4% of patients received a MoM bearing.

At 33 weeks follow-up, 3,142 patients underwent a prosthetic revision. The univariate survival analysis showed antibiotic-impregnated cemented THR fixations had a significantly lower rate of revision (2.4%) vs. uncemented THR fixations (3.3%). The revision risk for antibiotic-free cemented THRs was not significantly different than that for uncemented THR fixations.

In the univariate analysis, men had a higher revision risk than women. Furthermore, younger patients had a higher revision risk than older patients.

Prognosis

The results showed CoC and MoM THR both had worse prognoses than MoP THR (hazard ratios of1.11 and 1.32, respectively).

In the multivariate analysis, which had results that were similar to those of the univariate analysis, antibiotic-impregnated cemented THR had a better prognosis than uncemented THR after investigators adjusted for other risk factors, including bearing type.

“After 33 months of follow-up, cemented THRs have a better prognosis. MoM THRs have a slightly worse prognosis,” Zureik said.

The association between cement type and survivorship was more evident in the women studied. According to Zureik and colleagues, this could be due to a difference in patients’ bone quality. – by Robert Linnehan

Reference:
Colas S, et al. JAMA Surg. 2015;doi:10.1001/jamasurg.2015.1325.

For more information:
Mahmoud Zureik, MD, PhD, can be reached at French National Agency for Medicines and Health Products Safety, 143/147, boulevard Anatole France, 93285 Saint-Denis Cedex, France; email: mahmoud.zureik@ansm.sante.fr.

Disclosure: Zureik reports no relevant financial disclosures.