Abstract
Hip Resurfacing Arthroplasty (HRA) is a surgical technique that has become more popular in recent years for the treatment of hip osteoarthritis in young patients. For these patients, an HRA offers the advantages of preserving the physiologic anatomy of a patient's femoral head size and neck offset, which has been theoretically suggested to improve range of motion and muscle function, as well as preserving bone stock for future revision surgeries. Although the improvements in quality of life outcomes in patients undergoing total hip arthroplasty (THA) are well-documented, there is a lack of literature documenting the improvements in quality of life in patients undergoing HRA.
MATERIALS AND METHODS
One hundred and four consecutive patients presenting for elective HRA at our institution were recruited between 2004 and 2008 for participation in this study, which was approved by the Ethics Review Board at our institution. The mean age was 51±6y, male:female ratio 79:24 and mean BMI of 29.7±4.4 Preoperative computed tomography (CT) scans were used to preoperatively plan each procedure, and intraoperative procedures were performed using individualized templates [Kunz M, Rudan JF, Xenoyannis GL, Ellis RE. Computer assisted hip resurfacing using individualized drill templates. J Arthroplasty 2010;25(4):600–6]. Surgery time was 90±28 min including time for intraoperative verification of templating accuracy. Mobilization with physiotherapy began within 24 hrs of surgery and continued until the patient was discharged, usually within 2–3 days of surgery. Each patient completed the modified Harris Hip Score (HHS), the UCLA activity rating, the SF-36 mental and physical health score and the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) questionnaires at their preoperative appointment, then at 6 months, 1 year and 2 years postoperative. In addition, radiographs were taken at these appointments to confirm component position, and to check for signs of loosening or heterotopic ossification. Chi-square and t-tests were used for within and between group comparisons on selected variables and across times.
RESULTS
Only four patients required revision to THA, with one case of avascular necrosis of the femoral head, one femoral neck fracture and two infections.
The mean of the preoperative modified Harris Hip Scores was 51±19.7 with a significant improvement in the mean score at 6 months, 1 and 2 years postoperative (p<0.01). The preoperative UCLA activity index averaged 4 (range 2–9), improving to a mean of 6 at 6 months (p<0.001) then at 1 to 2 years to 7 (p<0.001). Mental state and further assessment of physical function were performed using the SF-36 scores, with the physical score initially 27.5 and improving to 45.2 after 2 years (p<0.01). The mental component score (MCS) means were almost unchanged, from 50.3 preoperatively to 51.5 after 2 years (p<0.21). Further data processing showed that patients who began with a below-average mental score also had significantly worse WOMAC scores for pain, stiffness and function; these patient showed a significantly higher MCS at 2 years (p<0.05). Those whose MCS were above average preoperatively showed little difference after 2 years.
DISCUSSION
The computer-assisted surgical procedure allowed excellent reproduction of the patients' native anatomy, with an average postoperative difference in neck-shaft angle of 8°. We found that template-guided HRA provided reliable improvements in the patients' self-reported quality of life, based on improvements in the modified HHS, WOMAC, UCLA activity index, and SF-36 physical and mental scores. The stiffness scores did not improve as significantly as did the pain and function scores; we suspect this is partly due to the patients continuing to rely on coping mechanisms they used preoperatively to reduce the range of motion in their hips.
Regarding mental component scores, the lower MCS group had worse WOMAC scores preoperatively, as well as worse general physical and physical role subscales of the SF-36 and worse scores in all of the mental component subscales of the SF-36. It is difficult to determine causation because our study was not designed to focus keenly on mental components. However, it is reassuring that these patients with worse mental well-being experienced such significant improvements in their mental well-being with surgical management of their hip symptoms, and surgeons should thus not shy away from performing surgery on patients due to concerns that a patient's depressive symptoms may indicate a potential for a poorer result.
We conclude that template-guided HRA provided significant and reproducible improvements in patient quality of life, irrespective of preoperative mental well-being, making this procedure attractive for carefully selected patients with early-onset hip osteoarthritis.
