SLR - October 2023 - Yates
Title: Can hardware removal be avoided using bioresorbable Mg-Zn-Ca screws after medial malleolar fracture fixation? Mid-term results of a first in-human study.Reference: Herber V, Labmayr V, Sommer NC, et al. Can hardware removal be avoided using bioresorbable Mg-Zn-Ca screws after medial malleolar fracture fixation? Mid-term results of a first in-human study. Injury 2022 Mar;53(3):1283-1288.
Level of Evidence: IV, retrospective case series.
Reviewed By: Tommy Yates, DPM PGY-3.
Residency Program: Highlands/Presbyterian-St. Luke’s Medical Center, Denver, CO.
Podiatric Relevance: The ankle is the most common site of hardware removal in the human body. Most hardware removal procedures involving the medial malleolus take place within 12 months of the index surgery due to irritation of the skin and surrounding soft tissues by the screw heads. Bioresorbable screws made of a magnesium allows, available as a 3.5mm cannulated headed screw, may obviate the need for subsequent hardware removal.
Methods: 20 patients with closed, displaced medial malleolar fractures were treated with ORIF using a bioresorbable screw made of a magnesium allows containing 0.45% weight calcium and 0.45% weight zinc. All screws were 3.5mm, cannulated, and 40mm in length. Medial malleoli were either fixated with 1 or 2 screws. All patients had concomitant ORIF of at least the fibula using a standard titanium plate and screws. Patients were followed for a minimum of 12 months to assess radiographic reduction, ankle ROM, AOFAS, blood concentrations of magnesium and calcium, renal function, complications, and reoperations including hardware removals.
Results:
1 patient was lost to follow-up. There were no losses of reductions in the remaining 19 patients. Mean difference in ankle ROM compared to the non-operative extremity was 2 degrees. Mean AOFAS was 89.8. No patients were found to have statistically significant different levels of magnesium or calcium, or renal function (measured by eGFR) compared to their baseline pre-operative values. After 12 months, no bioresorbable screws were removed. None of these screws could be detected on plain film radiographs.17 of 19 remaining patients did have hardware removal of other standard titanium fixation in the fibula.
Conclusions: After 12 months, bioresorbable screws used to fixate medial malleolar fractures are safe and demonstrate good radiographic and patient-reported outcomes, without the need for hardware removal––which did occur for other metallic hardware implanted during the same procedure. This is an excellent study which could be used to justify the potentially increased cost of such implants compared to traditional metallic implants, when factoring for the cost savings by obviating a subsequent hardware removal surgery. I hope that this study helps guide the development of similar implants in other areas of the body where hardware removal procedures are common due to soft tissue irritation.