Tibial lengthening in achondroplasia patients aged 6-9 years as the first stage of growth correction

Background Height increase and improvement of body proportions for achondroplasia patients normally require two or more stages of reconstructive treatment to be followed by rehabilitation between lengthening periods, and growth correction can take a significant part of life in the cohort of patients. What is the best age to start growth correction is an important question. The purpose of this paper was to present an argument for arranging the first stage of growth correction in achondroplasia patients aged 6-9 years based on the structural and functional muscle evaluation of tibiae to be lengthened. Material and methods Achondroplasia patients aged 6-9 years (n = 30) were examined preoperatively, during distraction, fixation and at 1.5 to 2 years of frame removal. Tibial lengthening was produced monofocally and bifocally. Contractile force of the dorsal and plantar flexion muscles of the foot was measured with dynamometer. Ultrasonography of tibial muscles was performed with HITACHI ultrasound imaging device (Japan). Results Achondroplasia patients aged 6-9 year who underwent tibial lengthening of at least 50% of the initial length developed neuropathy in 2.6 % of cases and soft tissue inflammation in 5.6 % of cases. Characteristic muscle striation of m. tibialis anterior and m. extensor digitorum longus appeared to restore at 1.5 to 2 years of tibial lengthening with clear contouring of the intermuscular septa and retained contractile force of the muscles. The contractile force restored to 96.15 % of preoperative level in the anterior tibial muscles, and to 101.92 % in the posterior muscles. Conclusion The comprehensive clinical, ultrasonographic and dynamometric evaluation of tibial muscles presented a good argument for tibial lengthening in achondroplasia patients aged 6-9 years. Regained muscle striation and spare capacity of m. tibialis anterior and extensor digitorum longus, the restored force of the anterior tibial muscles to 96.15 % of the preoperative level suggested the possibility for the next stage of growth correction.