Biodegradable Magnesium Screws for Unstable Ankle Fracture Surgery

Background: A substantial proportion of operatively treated lower-extremity injuries are ankle fractures, including unimalleolar, bimalleolar, bimalleolar-equivalent, and trimalleolar patterns, often with associated distal tibiofibular syndesmotic instability. Conventional metallic fixation provides reliable initial stability but carries well-recognized drawbacks, including hardware irritation, implant breakage or loosening, and the frequent need for secondary removal procedures-particularly for syndesmotic screws. Magnesium-based biodegradable implants are designed to provide sufficient mechanical stability during fracture healing while gradually degrading, thereby eliminating routine hardware removal. RemeOs magnesium-based screws (Bioretec), composed of a magnesium-calcium-zinc alloy, medial malleolus ankle fractures and are absorbed over approximately 2 to 3 years. Design: This is a prospective, single-arm, interventional, post-market clinical follow-up study. A minimum of 25 patients (planned enrollment of 28 to allow for attrition) will be enrolled at participating Mass General Brigham sites. Fellowship-trained orthopaedic foot and ankle surgeons will perform all procedures. Intervention: All participants will undergo open reduction and internal fixation (ORIF) of their ankle fracture using RemeOs magnesium-based biodegradable screws for fracture fixation and/or syndesmotic stabilization, in accordance with the device Instructions for Use. RemeOs screw types (Screw LAG, Screw COM, Screw FT, and Screw LAG Solid) may be used at the surgeon's discretion. Fixation of additional fracture components may be supplemented with plates, K-wires, or non-resorbable screws as clinically indicated. Assessments: Participants are evaluated preoperatively (baseline characteristics, radiographs, and patient-reported outcomes) and postoperatively at 6 weeks, 3 months, 6 months, and 12 months, with an optional 9-month visit if delayed healing or complications are suspected. Each follow-up includes clinical examination, radiographic assessment of healing and screw biodegradation, complication assessment, and patient-reported outcomes. Primary outcome: Functional recovery measured by the Olerud-Molander Ankle Score (OMAS) at 12 months. Secondary outcomes: OMAS at 3 and 6 months; radiographic fracture healing and alignment; radiographic evaluation of RemeOs screw biodegradation; complication rates (loss of fixation, infection, non-union, revision surgery); pain intensity (Visual Analog Scale); and PROMIS Physical Function and Pain Interference. Statistical analysis: Longitudinal OMAS changes will be analyzed using a linear mixed-effects model with time as a fixed effect and subject as a random effect. Secondary outcomes will be summarized descriptively; continuous variables compared with paired t-tests or Mann-Whitney U tests as appropriate; time to revision evaluated by Kaplan-Meier analysis where applicable. A p-value \< 0.05 is considered significant. All clinical procedures (surgery, imaging, follow-up) are standard care delivered regardless of study participation; the only research-specific procedures are informed consent and completion of patient-reported outcome measures.