Retrograde Femoral Lengthening Below a Total Hip Arthroplasty.

Abstract

Background: Limb length discrepancy (LLD) after total hip arthroplasty (THA) is a common occurrence and can lead to back pain, disordered gait, and decreased functional outcomes. Femoral lengthening ipsilateral to a THA using a retrograde motorized intramedullary lengthening nail (MILN) is a hip-sparing option for limb equalization. There has been little published on the technique and results of this method.

Methods: We retrospectively reviewed all patients at our institution who underwent unilateral femoral lengthening using a retrograde MILN ipsilateral and distal to a THA between April 2016 and June 2022. We describe the technique and considerations for this procedure in detail and report the patient demographic variables, etiology and magnitude of LLD, concomitant deformity, knee range of motion, time to union, and all adverse events and complications.

Results: Eleven lengthening procedures were included in this cohort. Etiology for LLD included osteonecrosis (4); postinfection (3); and one each of post-trauma, congenital deficiency, hip dysplasia, and iatrogenic discrepancy secondary to the index THA procedure. The mean lengthening was 35.7 ± 14.7 mm (range 20 to 70 mm) with a lengthening index of 1.5 ± 1.2 months until union per cm of lengthening. Complications included two patients who required reamed exchange nailing to achieve union and one interprosthetic fracture treated with removal of the MILN and plate fixation. No adverse effects on THA function were documented.

Conclusion: Femur lengthening using a retrograde MILN ipsilateral to a THA is a safe and reliable hip-sparing option for post-THA limb length equalization.