Extramedullary Internal Limb Lengthening

Abstract

Extramedullary implantable limb lengthening (EMILL) uses an implantable nail attached to the bone like and internal-external fixator. Cantilever forces can be neutralized by inserting a small diameter solid rod as a guide inside the medullary canal. EMILL expands the indications for internal limb lengthening to younger children with smaller diameter and length bones and to bones with impassable medullary canals. One must follow the same principles as with external fixation lengthening including prevention of joint subluxation and contracture by preparatory surgery (eg, pelvic osteotomy), soft tissue releases, temporary arthrodesis, and bracing. Lengthening should be restricted to amounts no >5 cm to avoid complications. A retrospective review of EMILL cases performed at the authors' institution since 2015 was performed. Thirteen patients underwent 14 EMILL procedures; 10 femurs and 4 tibias. Twelve of 13 patients lengthened to within 5 mm of their preoperative goal. There were no mechanical nail failures. No patient had a significant axial deviation of the bone during distraction. Three patients required unplanned operations. EMILL is safe and effective in patients who would otherwise require external fixation.