Treatment of Hypertrophic Distal Tibia Nonunion and Early Malunion With Callus Distraction

Background: Hypertrophic nonunions and early malunions of pilon and distal tibia fractures result in complex, challenging to treat deformities. Callus distraction histiogenesis is an option for their management, allowing for the simultaneous correction of multiplanar deformity and limb length discrepancy. Methods: A single-surgeon, retrospective case series was performed. Eight patients (6 males and 2 females) who were treated with callus distraction from 1991 to 2011 were reviewed. Six of 8 patients had varus deformities (range, 8-19 degrees) and 2 patients had valgus deformities (both 16 degrees) of the distal tibia metaphysis. Six of 8 had apex anterior deformities (range, 2-21 degrees) and 2 had apex posterior deformity (range, 9-20 degrees). An Ilizarov fixator or Taylor Spatial Frame (Smith & Nephew, Memphis, TN) was used to distract the nonunion or early malunion to correct alignment and shortening. Preoperative and postoperative radiographic outcomes, limb alignment, and ankle-hindfoot scores were reviewed. Results: Union was achieved in all patients at a mean of 5.8 months (range, 4.1-7.6 months). The 3 patients treated with an Ilizarov-type fixator had deformity correction to within 5 degrees of neutral in 1 plane and to within 10 degrees in the other plane. All 5 patients treated with a Taylor Spatial Frame had correction to within 5 degrees of neutral alignment in both coronal and sagittal planes. There were 2 complications requiring reoperation and 1 persistent limb length discrepancy (2 cm) after treatment. Median AOFAS ankle-hindfoot score was 82.5 (range, 53-90) at an average follow-up of 30.4 months (range, 8-92). Conclusions: Callus distraction histiogenesis was a minimally invasive technique that can successfully treat patients with hypertrophic nonunion and early malunion of the distal tibia. We believe the application of a computer-assisted 6-axis frame to correct the deformity improved the correction of these multiplanar deformities. Level of Evidence: Level IV, case series.