Background: Redislocation after an open reduction for develpmental dislocation of the hip is relatively common. The purpose of this study was to determine if the use of a transarticular pin (TAP) is safe and effective in maintaining reduction.
Methods: A total of 578 patients (645 hips) were reviewed after an open reduction, mean age at the time of surgery was 2.1 years. In 621 cases a smooth Kirschner wire was placed across the joint. The rates of redislocation, avascular necrosis (AVN), and other complications were determined. AVN was classified according to Kalamchi et al. Outcome was determined at a minimum of 6 years using the Severin classification.
Results: Redislocation occurred in 27 cases (4.1% rate), 24 had a TAP (3.8%) and 3 did not (12.5%). AVN was observed in 127 cases (19.7%), it was type I in 73 cases, type II in 38 cases, type III in 14 cases, and type IV in 2 cases; AVN was seen in 123 cases which had a TAP (19.8%) and 4 cases which did not (16.7%). Analyzing pin placement: when it was in the inferior third of the neck the rate of AVN was 15.2% (32/211), in the middle third it was 21.7% (71/326), and in the superior third it was 28.6% (24/84). According to the Severin classification for the hips with a TAP, 496 were type I or II (79.8%), 113 were type III (18.2%), 10 were type IV (1.6%), and 2 were type V (0.3%); in the group without a TAP 19 cases were type I or II (79.2%), 4 were type III (16.7%), and 1 was type IV.
Conclusions: The use of a TAP was effective in maintaining reduction and was not associated with significant morbidity. Placing the pin in the inferior third of the neck was associated with the lowest rate of AVN.
Level of evidence: Level IV--therapeutic.