Abstract
Background and purpose — The theoretical mechanical advantages of metal-on-metal hip resurfacing (MoM-HR) compared with conventional total hip arthroplasty (THA) have been questioned. Studies including measures of patient-reported function, physical activity, or health-related quality of life have been sparse. We compared patient-reported outcomes in MoM-HR patients with a matched group of patients with conventional THA at 7 years post-surgery.Patients and methods — Patients and patient data were retrieved from the Swedish Hip Arthroplasty Register. The case group, consisting of 363 patients with MoM-HR, was matched 1:1 with a control group, consisting of patients with a conventional THA. Patients were sent a postal patient-reported outcome measures (PROM) questionnaire including the Hip Disability and Osteoarthritis Outcome Score (HOOS), EQ-5D, and VAS pain. We used multivariable linear regression analyses to investigate the influence of prosthesis type.Results — 569 patients (78%) returned the questionnaire with complete responses (299 MoM-HRs and 270 conventional THAs). MoM-HR was associated with better scores in HOOS function of daily living (4 percentage units) and HOOS function in sport and recreation (8 percentage units) subscales. Type of prosthesis did not influence HOOS quality of life, HOOS pain, HOOS symptoms, EQ-5D index, hip pain, or satisfaction as measured with visual analog scales.Interpretation — At mean 7 years post-surgery, patients with hip resurfacing had somewhat better self-reported hip function than patients with conventional THA. The largest difference between groups was seen in the presumed most demanding subscale, i.e., function in sport and recreation.
Highlights
569 patients (78%) returned the questionnaire with complete responses (299 metal-on-metal hip resurfacing (MoM-HR) and 270 conventional total hip arthroplasty (THA))
Both the crude and adjusted estimates (Figure 2) showed that MoM-HR was associated with better scores in Hip Disability and Osteoarthritis Outcome Score (HOOS) ADL (4.3, confidence intervals (CI) 1.8–6.9), and Sport/Rec (7.8, CI 3.8–12)
We found no statistically significant association between type of prosthesis and remaining HOOS subscales, EQ-5D index, hip pain visual analogue scale (VAS), or satisfaction VAS
Summary
569 patients (78%) returned the questionnaire with complete responses (299 MoM-HRs and 270 conventional THAs). In 2011, the Finnish Arthroplasty Register (Mäkelä et al 2011) reported a 15-year prosthesis survival rate of about 70% in patients younger than 55 years operated with conventional total hip arthroplasty (THA) compared with about 90% in patients older than 60 years in the combined Nordic Arthroplasty Registers (Havelin et al 2009). Young patients have higher expectations following THA (Scott et al 2012) and are more active, a patient-factor highly related to polyethylene wear (Schmalzried et al 2000). They are more prone to participate in high-impact sports following THA (Williams et al 2012), which has been correlated with both increased wear (Ollivier et al 2012) and higher revision rates (Flugsrud et al 2007). Geons promptly stopped using the technique, due to perceived risks and the uncertainty regarding the long-term results of the implants (Cohen 2011)
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