Improved comfort in lower limb lengthening with the intramedullary skeletal kinetic distractor - Principles and preliminary clinical experiences

Introduction: Limb lengthening by external fixators is associated with many problems such as pain at the pin tracts, muscle transfixation, pin tract infections, reduced joint motion, and prolonged fixation time. The intramedullary skeletal kinetic distractor (ISKD) is a new internal, mechanically activated implant, which distracts by mild rotations of 3degrees. Material and methods: In a prospective clinical study, four patients with an mean age of 29 years (18-36 years) underwent intramedullary lengthening via ISKD. The average lengthening of three femora and one tibia was 31 mm (26-40 mm). Results: All patients performed the rotations for the distraction themselves without any significant problems. One patient took mild analgesics during the first days of distraction, whereas three patients did not require any analgesics. The average patient discharge occurred 10 days (8-11 days) postoperatively with no complications during the hospital stay. The planned length of distraction was achieved in all patients with normal alignment and normal joint orientation. Full weight bearing was performed on average after 10 weeks (7-14 weeks). Consolidation was noted 80 days (51-111 days) postoperatively with an average consolidation index of 2.9 days/mm. No complications were observed during the follow-up period of 14 months. The Enneking score was 26.8 points, and according to the classification of Paley all patients had an excellent result. Conclusions: From these preliminary results we conclude that the comfort of limb lengthening with the ISKD is increased by the elimination of fixator-associated complications and by the simple distraction mechanism, which is well tolerated by the patients. Further advantages of the ISKD are early full weight bearing and excellent limb function.