Intermediate to long-term results of periacetabular osteotomy in patients younger and older than forty years of age.

BACKGROUND The treatment of middle-aged patients with periacetabular osteotomy remains controversial. The goal of the present retrospective study was to analyze the intermediate to long-term functional and radiographic results of periacetabular osteotomy in patients below and above the age of forty years. METHODS Between February 1990 and December 2004, 166 periacetabular osteotomies were performed in 146 patients. We evaluated 158 hips in 139 patients who had a mean age of thirty-two years at the time of surgery. The mean duration of follow-up was eleven years (range, five to twenty years). We compared thirty-six patients (forty-one hips) who were forty years of age or older with 103 patients (117 hips) who were younger than forty years of age at the time of surgery. RESULTS The average Harris hip score increased from 70 points preoperatively to 90 points postoperatively. The mean Harris hip scores at the time of the five-year follow-up were similar in the older and younger groups (p = 0.57), although the latest follow-up scores were significantly higher in the younger group than in the older group (91 compared with 88 points; p = 0.02). The average modified Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) function score (with 0 representing the worst score and 100 representing the best score) was higher for the younger group than for the older group (92 compared with 90 points; p = 0.03). Kaplan-Meier analysis with progression of the Tönnis grade of osteoarthritis as the end point showed a ten-year survival rate of 90.8% (95% confidence interval, 88.3% to 93.3%) and a fifteen-year survival rate of 83.0% (95% confidence interval, 78.5% to 87.5%); the ten-year survival rates in the younger and older groups were 94.4% and 81.3%, respectively, and the fifteen-year survival rates were 86.9% and 71.2%, respectively (p = 0.025). CONCLUSIONS Periacetabular osteotomy yielded similar results for the two groups at the time of the five-year follow-up, although the results for the older group deteriorated thereafter. Decrease in physical function due to aging and increased susceptibility to the progression of osteoarthritis may be responsible for the poorer results over time in the older group.