Abstract
Introduction
The aim of this study was to compare patient reported outcomes, radiographic measurements, and survival free from total hip arthroplasty (THA) in patients who underwent periacetabular osteotomy (PAO) for mild, moderate, or severe developmental dysplasia of the hip (DDH).
Methods
We performed a retrospective cohort study on all patients (n=223, n=274 hips) who underwent a PAO procedure between May 1996 and May 2016, by a single surgeon at one academic center. Cases with a history of retroversion (n=64), Perthes (n=5), and those with <2 years of follow-up (n=63) were excluded. Patients were evaluated based on severity of dysplasia using the preoperative lateral center edge angle (LCEA): 18° – 25° was considered mild dysplasia (n=19), 10° – 17° moderate (n=62), and <10° severe (n=61). There was no difference in patient characteristics (age, sex, body mass index, or ASA score) between then cohorts (all, p>0.05). NIH PROMIS outcome measures included the physical function computerized adaptive test (PF CAT) and the Global 10 health assessment. Generalized estimating equations were used for all comparisons and missing data was imputed using the multivariate imputation by chained equations method. A Kaplan-Meier analysis was used to assess survival. Failure was defined as conversion to THA and follow-up was ended at time of failure or at the time of last follow-up. Mean follow-up was five years (1 – 19).
Results
Using the mild group as a reference, there was no difference in the PF CAT T-scores for moderate (p=0.167) or severe (p=0.910) dysplasia. These findings were similar for the Global physical and Mental Health T-scores (all, p>0.05). These outcomes were all within ½ of the standard deviation of the US general population (T-Score 50, SD 10) and demonstrate an average level of function or health. There was no difference in the numeric pain scores at last follow-up (all, p>0.05), with scores of approximately 2 – 3 units. There was no difference (all, p>0.05) in the proportion of patients achieving the correction goal for the LCEA (20° – 40°) where 95% (95% CI, 85% – 105%) of the mild group, 95% (95% CI, 90% – 100%) of the moderate group, and 76% (95% CI, 65% – 87%) in the severe group achieved this goal. The average amount of correction was roughly 12° (9° – 15°) in the mild, 15° (13° – 16°) in the moderate (p=0.185), and 23° (21° – 25°) in the severe group (p<0.001). The post-operative anterior center edge angle was in goal in approximately 70% – 80% of the cases for all groups (all, p>0.05). The post-operative acetabular index was within goal in roughly 65% – 75% of the cases in each group (all, p>0.05). Survival free from THA at five years was 100% for the mildly dysplastic, 92% (77% – 98%) for moderately dysplastic, and 96% (85% – 99%) for severely dysplastic hips (p=0.696).
Conclusion
Although requiring less correction than hips with moderate or severe dysplasia, we found PAO for mild dysplasia to be associated with promising patient reported outcomes, consistent with that of the general US population, and excellent survivorship at 5 years. Future studies should compare these results to hip arthroscopy in the setting of mild hip dysplasia.
