Age at Periacetabular Osteotomy Does Not Reduce the Likelihood of Excellent 20-Year Patient-Reported Outcomes in Native Hips: A K-Means Clustering Analysis.

Abstract

Periacetabular osteotomy (PAO) is widely used to treat symptomatic hip dysplasia; however, the long-term effect of age at PAO on patient-reported outcome measures (PROMs) remains controversial. We aimed to determine whether age at PAO influences long-term PROMs. We conducted a retrospective cohort study involving 111 patients (126 hips) who had a mean follow-up of 19.5 years after PAO. The Forgotten Joint Score-12 (FJS-12) and Oxford Hip Score (OHS) were collected via postal survey. Patients were clustered into three groups using k-means clustering based on PROMs. A cluster with the highest scores-exceeding the patient acceptable symptom state threshold for FJS-12 and showing differences beyond minimal clinically important difference-was defined as "excellent." The remaining native hips and those converted to total hip arthroplasty (THA) were grouped as controls. Multivariable logistic regressions identified indicators of excellent outcomes. The "excellent" group (n = 64) had mean scores of FJS-12: 84.1 and OHS: 46.6. The control group (n = 93) included native hips with lower PROMs and 31 hips converted to THA. The mean age at PAO was 41 years in the excellent group and 44 years in controls (P = 0.133). Age at PAO was not a negative indicator of excellent outcomes (adjusted odds ratio (OR) per year, 1.02; 95% confidence interval (CI), 0.98 to 1.06). Using Tönnis Grade 1 as a reference, Grade 0 was a positive indicator (OR 3.35; 95% CI, 1.16 to 10.5), and Grade 2 was a negative indicator (OR 0.13; 95% CI, 0.04 to 0.37). Higher BMI was also a negative indicator (OR per unit, 0.83; 95% CI, 0.73 to 0.94). Age at PAO does not reduce the likelihood of excellent 20-year PROMs in native hips. Therefore, age alone should not be a limiting factor when considering PAO in appropriately selected patients.