Rate of Correction and Recurrence of Ankle Valgus in Children Using a Transphyseal Medial Malleolar Screw

SLR - October 2015 - Sonia Mvuemba

Podiatric Relevance: Pediatric ankle valgus, which can be idiopathic in nature or as a result of multiple hereditary etiologies including cerebral palsy and spina bifida, may lead to gait instability, fibular impingement, difficulty with shoe gear and pain. Transphyseal medial malleolar screw (TMMS) hemiepiphysiodesis is an effective way of correcting such deformity. However, there is limited evidence on the effect of age and diagnosis on the correction rate as well as the rate of recurrence following removal of the screw. Therefore, the aim of this study was to determine the rate of correction achieved after hemiepiphysiodesis using a TMMS.  It also looked at the effects of clinical diagnosis and age at time surgery on the rate of correction and the rate of valgus recurrence after TMMS removal.

Methods: After approval from their institutional review board, a retrospective review of the authors’ surgical database was conducted to identify patients who underwent a TMMS hemiepiphysiodesis between July 2001 and July 2012. The inclusion criteria consisted of a diagnosis of ankle valgus, age between 2 and 16 at the time of surgery or a minimum of one year of follow-up post-surgery or within six months of removal of the screw. Patients were excluded from the study if they had inadequate radiographs or if they had undergone any other procedure on the ipsilateral limb, which could interfere with the outcome of the intended surgery. A total of 67 ankles from 37 patients were included in the study (16 males and 21 females). The tibiotalar angle in pre- and post-operative AP radiographs were measured by one of the authors. Surgery was indicated if the patient was symptomatic (pain), had more than 5 degrees of ankle valgus, brace intolerance and had a least a year left of skeletal growth. A partially threaded 4.0 cannulated screw was used for the procedure and serial radiographs were obtained every four months following the surgery.

Results: The average rate of correction in the tibiotalar angle was 0.37 ± 0.004 degrees per month. The amount of post-operative correction was significantly affected by the age of the patient at the time of the surgery and by the initial clinical diagnosis. In addition, the recurrence of the ankle valgus deformity following removal of the screw was observed in 18 of the 22 patient who underwent screw removal, with an average rate of recurrence of 0.28 ± 0.08 degrees per month.

Conclusions: The study concluded that TMMS hemiepiphysiodesis is an effective mean of treating pediatric ankle valgus; however, one should take into consideration the effects that additional skeletal growth could have in the recurrence of ankle valgus following correction and screw removal.