SLR - October 2023 - Cherian
Title: Identification of Fine Wire and Half‐Pin Loosening for External Fixators: A Systematic ReviewReference: Nutt J, Sinclair L, Graham SM, Trompeter A. Identification of fine wire and half-pin loosening for external fixators: A systematic review. Journal of Limb Lengthening & Reconstruction. 2022 Oct. 8(Suppl 1):p S51-S58.
Level of Evidence: Level 3
Reviewed By: Asher Cherian, DPM
Residency Program: Temple University Hospital, Philadelphia, PA
Podiatric Relevance: As loosening of half-pins and fine-wires can lead to bone necrosis, cortical osteolysis, skin necrosis, and infection, identifying precursors to loosening is vital to use of this fixation technique. By systematically reviewing studies that address the measurement of half-pin and fine wire loosening in external fixators, the manuscript provides insights into the efficacy and potential challenges of using these devices in foot and ankle surgery. This information can be crucial for foot and ankle surgeons in ensuring the stability and efficacy of external fixators during procedures, thus contributing to improved patient outcomes and safety in the realm of foot and ankle surgical interventions.
Methods: A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. This review encompassed studies that examined the utilization of external fixators and provided information on the measurement of loosening in half-pins and fine wires.
Results: The study's findings revealed eight studies which met the eligibility criteria and were included in the analysis. However, no randomized controlled trials were identified in the selected studies. The assessment of the interface between the half-pin and bone was most frequently accomplished using torque measurement. Histological analysis was conducted by three of the included studies, while radiographic analysis, employing techniques such as plain film and micro-computed tomography (CT), was performed by five of the papers.
Conclusions: The study underscores diverse methods for evaluating half-pin loosening—clinical, biomechanical, radiological, and histological—lacking comparative validation. The frequently used torque index requires risky extraction torque, while insertion torque offers probability of loosening over time. An optimal method should measure without compromising the pin-bone interface, be reproducible, and patient-friendly. Only one study used such a method—micro-CT scanning—without a scale for quantifying loosening. As multicenter trials comparing methods are lacking, authors suggest designing studies for an evidence-based definition of loosening. They propose correlating in vivo extraction torque with modern radiographic analysis, like the pixel value ratio (PVR) method, to quantify radiolucency. The findings will advance patient care by guiding improved treatment approaches. Understanding the limitations of the torque index and the need for more reliable measurement methods will inform clinicians in external fixator usage. Pursuing safer and patient-friendly techniques could minimize complications. The study's emphasis on standardized definitions and correlation between measurement methods and radiographic analysis will shape future research, leading to enhanced foot and ankle surgery outcomes with external fixators.