An analysis of variables affecting the duration of Pavlik harness treatment: Is it possible to predict the duration of treatment?

Background: Pavlik harness is the initial treatment for the infants with developmental dysplasia of the hip who have not yet begun walking. Objectives: The present study evaluates the variables which affect the duration of PH treatment for patients successfully treated. Study design: Cross-sectional study. Methods: Pavlik harness was employed for 140 hips of 87 patients with developmental dysplasia of the hip in our institution between 2010 and 2013. In all, 55 hips of 46 patients who were treated successfully with Pavlik harness were included in this study. According to Graf's sonographic classification, 23 hips were Type IIC, 26 were Type IID, and 6 were Type III. The studied variables were (1) alpha angle, (2) age at the start of treatment, (3) laterality, and (4) gender. The variables were compared with the duration of Pavlik harness treatment. Results: A highly significant inverse correlation was observed between Pavlik harness application time and alpha angle at the start of the treatment (r=-0.050; p<0.001). Bilateral involvement has statistically longer duration, when compared with unilateral involvement (r=0.28; p=0.036). No statistically significant difference was present between duration of treatment and age at the start of Pavlik harness treatment (r=-0.034; p=0.804). There was no statistical significance between gender and duration of Pavlik harness (r=0.201; p>0.05). Conclusion: The duration of treatment was negatively correlated with the initial alpha angle. A change of 1 degree in alpha angle may alter the duration of treatment as 0.89week calculated by the formula (Application time (Week)=56.6-0.89xalpha angle). Bilateral involvement may need longer Pavlik harness treatment. Clinical relevance Pavlik harnes generally is the first treatment method for the infants with DDH. This study suggest conclutions about how long time is the Pavlik harness should be kept on the infants? The main indicator is initial alfa angle which is negatively correlated with the duration of treatment.