Background: Treatment of developmental dysplasia of the hip (DDH) using the Pavlik harness has been a widely used method in patients between 0 and 6 months of age for many years. However, the factors influencing the success rate of this treatment modality have still not exactly been determined as a result of the limited number of clinical studies with higher level of evidence.
Questions/purposes: We, therefore, asked whether (1) patient-related variables such as age, gender, and laterality; coexisting risk factors including family history, breech presentation, intrauterine packing, first-born girl, oligohydroamnios, and swaddling; and (2) the severity of hip dysplasia, defined by ultrasonography, are associated with differences in the success rate of Pavlik harness treatment in infants with DDH.
Methods: Between 2012 and 2014, we treated 153 children (≤ 6 months of age) with DDH using the Pavlik harness. Hip dysplasia apart from coexisting neuromuscular disorders, congenital abnormalities, or syndromes was our inclusion criteria. Of patients thus treated, 130 (85%) were available for the evaluation of patient- and hip-related variables against the success of Pavlik harness treatment. Mean age of these patients on day of diagnosis and initiation of treatment was 108 days. The diagnostic and followup examinations of the hips were made by ultrasonography using Graf's method. Pavlik harness treatment was initiated in Graf Type IIa- and worse hips and treatment was considered "successful" when a Graf Type I hip was achieved. Pavlik harness treatment was successful in 92 (71%) patients (130 of 181 hips [72%]).
Results: Age was the only patient-related variable influencing the success rate of the treatment; the mean age of children in whom Pavlik harness treatment succeeded (97 ± 38 days; 95% confidence interval [CI], 90-112) was lower than the age of those who failed (135 ± 37 days; 95% CI, 123-147; p < 0.001). The highest success rate was obtained in children younger than age 3 months (37 of 40 [93%]) and the lowest one older than age 5 months (nine of 24 [37%]) (p < 0.001). The threshold age value related to an increased risk of failure was found to be 4 months and older, which had a sensitivity of 66% and a specificity of 77% (p < 0.001). A higher initial α angle was observed in the hips in which the treatment succeeded (53° ± 6°; 95% CI, 51°-53°) than in those that failed (47° ± 7°; 95% CI, 45°-50°; p < 0.001). The threshold α angle value related to an increased risk of treatment failure was 46° and less, which had a sensitivity of 47% and a specificity of 86% (p < 0.001). Dislocated hips (Graf Type III and IV hips) had the lowest rate of treatment success (five of 19 [26%] and two of four [50%], respectively), whereas Graf Type IIa- hips had the highest (27 of 29 [93%]) (p < 0.001).
Conclusions: We conclude that Pavlik harness treatment is less effective in children at and over the age of 4 months at the time the harness is first applied as well as in hips with complete dislocations and hips with severely deficient acetabular bony roofs. In such older patients and worse hip types, the use of initial Pavlik harness treatment needs to be revisited. Future studies, comparing the outcomes of the Pavlik harness treatment and other types of interventions in such patients and hip types, are needed.
Level of evidence: Level III, therapeutic study.