Submitted:
05 February 2026
Posted:
06 February 2026
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Abstract
Background: The inferior subluxation of the proximal part of the fibula have been reported to occur with distraction osteogenesis of the tibia with unilateral external fixation in achondroplasia. The purpose of this study was to evaluate the clinical and radiologic effects when the fibula head is not fixed to the tibia during the tibial lengthening in achondroplasic patients. Methods:We retrospectively reviewed all the achondroplasic patients who were underwent bilateral tibial lengthening by distraction osteogenesis with use of a unilateral external fixation between 2007 and 2016. Clinically and radiographically data related to mean age at the time of the surgery, amount of lengthening, proximal fibular migration, mean mechanical axis deviation were collected. The mean duration of follow-up was 7.4 years (range, 1.96-11years). Results:80 tibial lengthening procedures in 40 achondroplasic patients were evaluated. The mean age at the time of the surgery was 11.97 years old (range 9.30-16.40 years). The mean amount of lengthening was 15.03 +/- 1.56 cm (range 11.40-18.50 cm) and the mean percentage lengthening was 84.64 % (range 62.21 to 138%). The mean proximal fibular migration (PFM) was 19.09 ± 4.57mm (range, 10.48 to 29.37mm). The mean mechanical axis deviation (MAD) of 14.40 ± 11.95 mm (range, -22.45 to 59.74mm) preoperatively and 8.2 ±15,25mm (range, -21.91 to 49.88mm) at the final follow-up. We observed that the degree of proximal fibular migration was linearly correlated with the amount of tibial lengthening. The proximal fibular migration was not associated with the valgus deformity of the knee (p> 0.05). Our study showed a relation between the presence of valgus deformity and the magnitude of lengthening. We observe that the proximal fibular migration and the magnitude of lengthening were not associated with the presence of complications. Conclusions:The proximal fibular migration is common in patients undergoing bilateral tibial lengthening using unilateral external fixation. However, no valgus deformity or presence of major complications was found. These findings indicate that the fixation of the proximal tibiofibular joint is not required in bilateral tibial lengthening with unilateral external fixation in achondroplasic patients.
