What Are the Potential Benefits and Risks of Using Magnetically Driven Antegrade Intramedullary Lengthening Nails for Femoral Lengthening to Treat Leg Length Discrepancy?

• Published in: Clinical orthopaedics and related research 2022-04, Vol.480 (4), p.790-803
• Main Authors: Frommer, Adrien, Roedl, Robert, Gosheger, Georg, Niemann, Maike, Turkowski, Dominik, Toporowski, Gregor, Theil, Christoph, Laufer, Andrea, Vogt, Bjoern
• Format: Article
• Language: English
• Subjects: Accuracy; Adolescent; Bone implants; Bone Lengthening - adverse effects; Bone Lengthening - methods; Bone Nails - adverse effects; Clinical Research; Data acquisition; Distraction osteogenesis; Etiology; Female; Femur; Femur - diagnostic imaging; Femur - surgery; Fracture Fixation, Intramedullary - adverse effects; Fracture Fixation, Intramedullary - methods; Humans; Knee; Leg; Leg Length Inequality - etiology; Leg Length Inequality - surgery; Male; Nails; Orthopedics; Osteogenesis, Distraction - adverse effects; Osteogenesis, Distraction - methods; Osteomyelitis; Patients; Retrospective Studies; Risk Assessment; Surgery; Transplants & implants; Treatment Outcome
• ISSN: 0009-921X; 1528-1132
• DOI: 10.1097/CORR.0000000000002036

Limb lengthening with magnetically driven intramedullary lengthening nails is a fast-developing field and represents an alternative to external fixators. Although previous studies have assessed the application of magnetically driven intramedullary lengthening nails, these studies have been heterogenous regarding the nailing approach, the bone treated, and the implant type; they also have analyzed relatively small patient groups at short follow-up durations. (1) Is femoral lengthening with magnetically driven antegrade intramedullary lengthening nails accurate and precise? (2) What are the most common complications of treatment? (3) What factors are associated with unplanned additional surgery? We retrospectively analyzed the longitudinally maintained database of our orthopaedic teaching hospital to identify all patients who underwent surgery for leg length discrepancy (LLD) between October 2014 and April 2019. In total, we surgically treated 323 patients for LLD of 2 cm or more. Of those 55% (177 of 323) were treated with distraction osteogenesis with magnetically driven intramedullary lengthening nails, 18% (59 of 323) with external fixation, and 27% (87 of 323) with epiphysiodesis around the knee. Based on that, 29% (93 of 323) of patients underwent unilateral femoral distraction osteogenesis with magnetically driven antegrade femoral lengthening nails and were eligible for analysis. No patient was excluded, and 3% (3 of 93) were lost before the minimum study follow-up of 2 years, leaving 97% (90 of 93) for analysis. Patients with a distal femoral deformity were treated via a retrograde femoral approach (10% [33 of 323]) or with external fixators (3% [10 of 323]) and were not included in this study. Distraction osteogenesis with magnetically driven intramedullary lengthening nails was not considered for patients with deep tissue infection, those with bone dimensions considered to be too small in relation to the available implants, and for patients younger than 8 years. This study included 90 patients (44 females, 43 left femora) treated for a median (interquartile range) preoperative LLD of 39 mm (32 to 52) at a median age of 15 years (14 to 17). The same limb lengthening system was applied in all patients. The median (IQR) follow-up was 35 months (24 to 78). Data were acquired through a chart review performed by someone not involved in the surgical care of the included patients. Data acquisition was supervised and curated by two of the involved surgeons