Infection rates and risk factors with magnetic intramedullary lengthening nails

Abstract

Introduction: Surgical site infection (SSI) related to magnetic intramedullary lengthening nails (MILNs) can lead to delayed consolidation or loss of limb function, resulting in deleterious effects to a patient's quality of life. With the rise of MILNs, we sought to determine the incidence rate and risk factors for infection during limb lengthening with MILNs.

Methods: We reviewed a consecutive series of patients who underwent femoral and/or tibial lengthening with an MILN at a single institution between 2012 and 2020 (n = 420). SSI was defined according to CDC-NHSN criteria (including superficial and deep infections) with postoperative surveillance time of 12 months. Demographic, health metrics, comorbidities, limb- and surgery-related factors, were assessed as potential risk mediators of SSI.

Results: Incidence of SSI was 3.3 % (14/420). This was divided into superficial (0.5 %,2/420) and deep (2.9 %, 12/420) infections. Of deep infections, 75 % (9/12) were osteomyelitis. Of the 14 limbs that developed SSI, 57 % (8/14) had a history of prior external fixation in the same limb and 38 % (5/14) had a previous infection of the same limb. A subanalysis of patients with a history of prior external fixation in the same bone was associated with SSI, as compared to those without previous external fixation. None of the surgery-related infection risk factors reached statistical significance.

Discussion and conclusion: The total incidence of infection with MILNs was 3.3 % at 24 months follow-up. The risk of deep infection was 2.9 %. Patients with a history of previous external fixation and prior infection show an independent association with increased rate of infection recurrence in the same bone. These patients could be considered a high-risk group for developing deep tissue infection. Potential algorithms include prolonged oral antibiotics after MILN insertion or simultaneous injection of absorbable antibiotic at the time of the nail insertion.