100 patients scheduled for total hip arthroplasty were randomized to either a piriformis-sparing approach or a standard posterior approach. Patients were assessed over 10-year follow-up for pain, function, and satisfaction. Magnetic resonance imaging (MRI) was also performed in a subset of patients to evaluate piriformis muscle quality, including bulk and grade. After 10 years, despite significant differences in favour of the piriformis-sparing group for measures of piriformis muscle quality, no significant differences between groups were observed in pain, Oxford Hip Scores, 6-minute walk tests, or patient satisfaction.