Tibial lengthening over a bioactive degradable intramedullary implant: a case report

Introduction Long duration of distraction osteosynthesis remains an unsolved problem. One of the promising ways to stimulate reparative regeneration of bone tissue is the technology of combined osteosynthesis with intramedullary elastic reinforcement with titanium wires coated with hydroxyapatite. A significant drawback of this combined distraction osteosynthesis is the planned removal of intramedullary wires several months after disassembling the Ilizarov apparatus.The purpose of this work is to demonstrate the possibility of stimulating reparative regeneration and reducing the duration of distraction osteosynthesis using an intramedullary degradable implant with bioactive filling.Methods We present the first in clinical practice case of surgical leg lengthening in a female 10-year-old patient using the Ilizarov apparatus an intramedullary degradable implant made of polycaprolactone (PCL) saturated with hydroxyapatite to stimulate reparative regeneration in the tibia. Monthly radiographic monitoring of the process of reparative regeneration of bone tissue was supplemented by computed tomography after disassembling the Ilizarov apparatus.Results The process of lengthening the tibia was accompanied by pronounced formation of a bone “sleeve” around the implant, which was directly connected to the endosteum of the tibia. The density of bone substance in the medullary canal reached 496.6 HU. The cortical layer of the tibia in the elongation zone increased to 4 mm, and its density was equal to 1288.8 HU.Discussion Leg lengthening of 4 cm was achieved along with simultaneous correction of valgus recurvatum bone deformity at IO = 15 days/cm, that is two times shorter than the generally accepted excellent IO in distraction osteosynthesis according to Ilizarov.Conclusions Biodegradable polycaprolactone implants saturated with hydroxyapatite might be not inferior to titanium wires coated with hydroxyapatite in regard to the degree of osteoinduction and do not require repeated surgical intervention to remove them.