Two-stage Bone Lengthening With Reuse of a Single Intramedullary Telescopic Nail in Patients With Achondroplasia

Abstract

Background: Patients with achondroplasia may benefit from limb-lengthening surgery with telescopic intramedullary nails (TIMNs). However, the 5-cm maximum length of the nails used in these patients in their original design may be insufficient. The aim of this research is to analyze the outcomes and complications after reusing the same TIMN for a second consecutive 5-cm lengthening in patients with achondroplasia.

Methods: Retrospective study of 26 bones (16 femurs and 10 tibias) in 9 patients with achondroplasia treated for bilateral 2-stage sequential lengthening reusing the same TIMN. On completion of a first stage of 5 cm of elongation, the nail was unlocked, retracted, and re-locked; a second stage of 5 cm of distraction followed. Radiologic and clinical parameters were measured preoperatively and postoperatively, and complications were recorded.

Results: The median age of patients at first surgery was 13.54 (12.9 to 16.3) years; 55% were males. The median preoperative height was 121 (117.5 to 127) cm, and the median healing index was 18.12 (14.5 to 32.8) and 26.96 (23.3 to 31.6) d/cm, while time to weight bearing was 185.5 (144.8 to 308.5) and 242.5 (208.5 to 293.8) days for femurs and tibias, respectively. Major complications included 3 cases of moderate ankle equinus, 2 cases of hardware failure (failure to relengthen), 2 premature consolidations, 1 common peroneal neurapraxia, and 2 valgus deformities. Femoral procedures had significantly fewer complications than tibial interventions (7 vs. 15, P=0.03), whereas patients who underwent lengthening of both the femur and tibia did not have significantly higher complication rates (14 vs. 8, P=0.6).

Conclusions: This study analyzes lower-limb lengthening in a series of achondroplastic patients using TIMN with the novelty of nail reuse to relengthen the bone. The complication rate found is acceptable, among which, potential damage to the internal lengthening mechanism must be considered, though this complication can usually be easily resolved. Overall, nail reuse seems advisable in cases where bone elongation is indicated, and the size and design of the nail limits the extent of lengthening.

Level of evidence: Level III, retrospective comparative study, before and after intervention.