Study finds bearing type did not affect patient-reported THA outcomes

Issue: May 2016

Patient-reported outcomes for total hip arthroplasty had little association with the bearing type used in the procedure, based on results of a nationwide cross-sectional study conducted in Denmark.

Claus Varnum, MD, PhD, is scheduled to present results of the study in a patient-reported outcomes session at the 17th EFORT Annual Congress in Geneva.

Investigators found the use of ceramic-on-ceramic (CoC), metal-on-metal (MoM) and metal-on-polyethylene (MoP) bearings did not lead to significantly different patient-reported outcomes after total hip arthroplasty (THA), Varnum said.

Claus Varnum

“The difference in [hip disability and osteoarthritis outcome score] HOOS symptom scoring for patients with CoC and MoP [bearings] was statistically significant, but so small there is no reason to believe that this difference is clinically relevant. No other differences were found for patients having THA with CoC or MoM bearings compared to patients having MoP THA in relation to pain from the hip joint, activities of daily living and sporting activities, as well as quality of life,” he told Orthopaedics Today Europe.

Patient data

Varnum and colleagues identified 4,212 patients who underwent THA with CoC, MoM or MoP bearings between 2002 to 2009 from the Danish Hip Arthroplasty Register. None of the patients had a revision of their primary THA surgery listed in the register.

In total, 3,762 of those patients had were available for the questionnaire survey, including the EuroQol-5D (EQ-5D), UCLA activity and HOOS scores. The HOOS score included five subscales for pain, other symptoms, activities of daily living, sport and recreation function and hip-related quality of life.

Of those patients, 145 patients were excluded due to confirmed revision surgery after the patient cohort was generated from the register. In all, 3,082 patients responded to the investigators for a follow-up rate of 85%.

Younger patients had CoC or MoM bearings

Varnum and colleagues found CoC bearings were the most used among the study group, as 1,393 patients (45%) received that type of bearing. Their analysis showed 512 patients (17%) received MoM bearings and 1,177 patients (38%) received MoP bearings.

Patients with CoC and MoM bearings were significantly younger (aged 65.7 years, on average) than patients with MoP bearings (aged 67.4 years, on average).

The study data showed patients with CoC bearings also had lower mean HOOS symptom scores compared with patients who had MoP bearings. Varnum noted this indicated more symptoms occurred in patients with a CoC THA, but this difference was likely not clinically relevant.

“The symptoms part of the HOOS questionnaire includes five questions about feeling grinding or hearing any noise from the hip, difficulties spreading legs wide apart, difficulties to stride out when walking and further two questions about stiffness in the hip joint. Patients with CoC THA had lower HOOS symptom scores indicating [they had] more of these symptoms than compared to patients with MoP THA,” Varnum said.

However, he said there were no other significant differences between patients who had MoM, CoC or MoP THA patients for the HOOS subscale, EQ-5D index or UCLA activity scores. – by Robert Linnehan

Reference:
Varnum C, et al. Paper #1264. Scheduled to be presented 2 June 2016 at 11:30 to 12:30 in the Florence Room at 17th EFORT Annual Congress – A combined programme in partnership with swiss orthopaedics; 1-3 June 2016; Geneva.

For more information:
Claus Varnum MD, PhD, can be reached at Vejle Hospital, Kabbeltoft 25, 7100 Vejle, Denmark; email: claus.varnum@rsyd.dk.

Disclosure: Varnum reports no relevant financial disclosures.