The influence of soft tissue volume on the quality of distraction bone regenerate at lengthening of tibia bones according to Ilizarov in patients with achondroplasia (pilot study)

Rationale: The technique of operative limb lengthening has a severe complication as an insuffi t bone regenerate. Th s complication continues to occur frequently, although the technique of operative lengthening of segments and replacement of bone defects has been used since the middle of the 20th century. Th aim of the study was to investigate the influence of soft tissue volume on qualitative and quantitative X-ray morphometric indices of distraction bone regenerate during Ilizarov lengthening of the lower leg bones in patients with achondroplasia.Materials and Methods. The study included 10 patients with achondroplasia who underwent lengthening of both tibiae for the fi st time in the Ilizarov Center. The average age was 7 years. The average lengthening value was 67 mm. All patients were operated and supervised by an orthopedic surgeon with more than 10 years of experience. In all patients, tibial osteotomies were performed at the level of the metaphyseal zones minimally invasively. Distraction was started on the 4th day and continued at the rate of 1 mm/day.Results. By the end of the distraction phase in 2 patients the distraction regenerate corresponded to type II according to the Ru Li X-ray classifi ation [1], in 3 patients - to type III, in 4 patients - to type IV (at least in 1 of the projections), in 1 patient - to type V. Regenerate remodeling occurred in all patients. The maximum reduction of the muscle volume per 1 mm of length from the initial one was 32.4% on the average. The diameter of the narrowest part of the distraction regenerate (at least in 1 projection) ranged from 3.3 to 20.9 mm.Conclusion. A statistically signifi ant (at n=42, Spearman's correlation coeffi t was 0.420 at p=0.05) medium-explicit relationship between muscle volume per 1 mm of length and the smallest diameter of the distraction regenerate was found. The derivative is expressed by the formula y=0.006x+8.3. Based on this expression, the minimum desired diameter of the distraction regenerate can be calculated.