Department of Orthopaedic Surgery, Severance Children's Hospital, Yonsei University College of Medicine, Seodaemun-gu, Seoul, South Korea.
J Bone Joint Surg Am. 2011 Feb 2;93(3):294-302. doi: 10.2106/JBJS.I.01316.
Ankle valgus deformity secondary to proximal migration of the fibula following an Ilizarov tibial lengthening has not been discussed in detail in the literature. The purposes of this study were to determine the underlying mechanism of and to identify factors associated with proximal migration of the fibula that caused ankle valgus deformity after an Ilizarov tibial lengthening.
We reviewed the outcome of seventy-four bilateral Ilizarov tibial lengthenings for short stature in thirty-seven patients. The mean age at the time of surgery was 21.7 years (range, thirteen to thirty-one years), and the mean duration of follow-up was forty-five months. Proximal migration of the fibula was assessed with changes in the malleolar tip distance. A valgus change of ≥ 5° in the tibiotalar angle was regarded as ankle valgus deformity following tibial lengthening.
The average length gain was 6.9 cm (range, 4.7 to 11.5 cm), and the average lengthening index was 1.5 mo/cm. Valgus deformity developed in six ankles (8%) and fibular nonunion developed in ten (14%). Proximal migration of the lateral malleolus of ≥ 5 mm was related to valgus talar tilting. Bifocal tibial lengthening, rapid distraction rate of the fibula (>1 mm per day), and development of a fibular nonunion were factors associated with proximal migration of the distal end of the fibula of ≥ 5 mm, which suggests that regenerated bone of poor quality in the distraction gap may cause proximal migration of the distal end of the fibula following tibial lengthening.
Proximal migration of the distal end of the fibula following tibial lengthening may occur even with the use of an Ilizarov ring fixator. This migration seems to be caused by collapse of regenerated bone of poor quality or fibular nonunion. Proximal migration of ≥ 5 mm is associated with the risk of valgus talar tilting. Surgeons should consider earlier intervention with bone-grafting if there are conditions that compromise regenerated bone formation in the fibular distraction gap, such as can occur with extensive tibial lengthening by bifocal corticotomy.
伊里扎洛夫胫骨延长术后腓骨近端迁移导致的踝关节外翻畸形尚未在文献中详细讨论。本研究的目的是确定腓骨近端迁移导致伊里扎洛夫胫骨延长术后踝关节外翻畸形的潜在机制，并确定与腓骨近端迁移相关的因素。
我们回顾了 37 名患者 74 例双侧伊里扎洛夫胫骨延长术治疗身材矮小的结果。手术时的平均年龄为 21.7 岁（范围为 13 至 31 岁），平均随访时间为 45 个月。腓骨近端迁移通过距骨顶距的变化来评估。胫骨延长后，距骨关节角的外翻变化≥5°被视为踝关节外翻畸形。
平均长度增加 6.9cm（范围为 4.7 至 11.5cm），平均延长指数为 1.5mo/cm。6 个踝关节（8%）出现畸形，10 个（14%）出现腓骨不愈合。外侧距骨的近端迁移≥5mm 与距骨倾斜的外旋有关。双焦点胫骨延长、腓骨快速牵伸率（>1mm/天）和腓骨不愈合是腓骨远端近端迁移≥5mm 的相关因素，这表明牵开间隙中质量较差的再生骨可能导致胫骨延长后腓骨远端的近端迁移。
即使使用伊里扎洛夫环固定器，胫骨延长后腓骨远端也可能发生近端迁移。这种迁移似乎是由质量较差的再生骨塌陷或腓骨不愈合引起的。腓骨近端迁移≥5mm 与距骨倾斜的外旋风险相关。如果腓骨牵开间隙中存在影响再生骨形成的条件，如双焦点皮质切开术广泛延长胫骨，则应考虑早期进行植骨干预。
