Ankle fractures are among the most common injuries that need surgery. When the broken bones make the ankle unstable, surgeons usually fix them with metal screws and plates. Metal hardware holds the bones in place well, but it can cause irritation, can loosen or break, and often has to be removed in a second surgery later.

This study looks at a different kind of screw called the RemeOs magnesium-based screw. It is made from a magnesium alloy and is designed to slowly dissolve and be absorbed by the body over about two to three years after it has done its job of holding the bone together. Because it dissolves on its own, patients may not need a second surgery to remove the hardware. These screws are authorized by the U.S. Food and Drug Administration (FDA) for use in foot and ankle fracture surgery.

The purpose of this study is to learn how well these magnesium screws work and how safe they are when used to repair unstable ankle fractures. The study will enroll at least 25 adults (ages 18 to 80) who have an unstable ankle fracture that needs surgery. All participants will have their fracture repaired with RemeOs screws as part of their normal surgical care.

After surgery, participants will be followed for 12 months. They will return for check-ups at about 6 weeks, 3 months, 6 months, and 12 months. At these visits, the study team will examine the ankle, take X-rays to see how the bone is healing and how the screws are dissolving, ask about any complications, and have participants fill out questionnaires about their ankle function and pain.

The main thing the study measures is ankle function at 12 months, scored using a standard ankle questionnaire (the Olerud-Molander Ankle Score). The study also tracks pain, healing on X-rays, how the screws break down over time, and any complications such as infection, loss of fixation, non-healing, or the need for additional surgery.

The surgery, X-rays, and follow-up visits in this study are the same care patients would receive whether or not they take part. The only research-specific parts are giving consent and filling out the study questionnaires. Taking part is voluntary and does not change the care a patient receives.

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, are FDA-authorized for fracture fixation in foot and ankle surgery 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.

Inclusion Criteria:

• Age 18-80 years
• Unstable closed ankle fracture requiring surgical fixation, including unimalleolar, bimalleolar, bimalleolar-equivalent, or trimalleolar fractures
• Fractures may be with or without syndesmotic instability
• Willingness to follow postoperative visits and rehabilitation protocols
• Ability to complete patient-reported outcome measures (PROMs)

Exclusion Criteria:

• Body mass index (BMI) > 40
• Open fractures
• Pathologic fractures
• Active infection at the surgical site
• Known allergy or hypersensitivity to magnesium or implant components
• Severe peripheral vascular disease
• Uncontrolled diabetes mellitus
• Prior ankle surgery on the affected limb
• Concomitant osteochondral lesions requiring treatment
• Neuromuscular disorders affecting the lower extremity
• Worker's compensation cases
• Pregnancy
• Non-adherence concerns or inability to comply with follow-up requirements

Individual participant data will be stored within Mass General Brigham and accessed only by IRB-approved study staff. Per the study protocol, data will not be shared outside the institution, and no biological specimens are collected.