SLR - January 2018 - Jason Kim

Bioabsorbable Magnesium Versus Standard Titanium Compression Screws for Fixation of Distal Metatarsal Osteotomies: Three-Year Results of a Randomized Clinical Trial

References: Plaass C, von Falck C, Ettinger S, Sonnow L, Calderone F, Weizbauer A, Reifenrath J, Claassen L, Waizy H, Daniilidis K, Stukenborg-Colsman C, Windhagen H. Bioabsorbable Magnesium Versus Standard Titanium Compression Screws for Fixation of Distal Metatarsal Osteotomies: Three-Year Results of a Randomized Clinical Trial. Journal of Orthopaedic Science (2017).

Scientific Literature Review

Reviewed By: Jason Kim, DPM
Residency Program: NYU Langone Hospital Systems, Brooklyn, NY

Podiatric Reference: Hallux abducto valgus deformity is a common podiatric issue that may be corrected with a metatarsal osteotomy. Throughout the years, different fixation techniques have been introduced and utilized, including Kirschner wires, small fragment screws or headless compression screws. Problems have been associated with metallic implants, such as screw loosening, delayed bone healing, irritation by the implant itself and hypersensitivity/allergic reactions. With these potential problems, the necessity for hardware removal increases. Biodegradable implants were designed to combat the problems that arise with metallic implants. This study compares magnesium biodegradable screws to standard metallic implants across a three-year postsurgical follow-up.

Methods: A level II randomized control study was performed with an inclusion criterion of patients with symptomatic hallux valgus with an indication of a distal metatarsal osteotomy (Chevron) and with no prior additional surgery. Twenty-six patients were randomly assigned to either treatment with standard titanium or magnesium implant. At the end of the study, 14 patients were included who had full follow-up, including MRI scanning and clinical evaluation. Outcomes were evaluated preoperatively and three years postoperatively, including range of motion of the first metatarsal phalangeal joint, American Foot and Ankle Society Hallux metatarsophalangeal-interphalangeal (AOFAS) scores, Short Form (SF-36) scores and visual analog scale (VAS).

Results: Both standard metallic implant and magnesium implants showed no significant difference in AOFAS scores and pain scores. Both groups showed improvement in both AOFAS and pain scores with no significant differences between the two groups. Also, at the three-year follow up, there was no significant difference in the range of motion at the first metatarsophalangeal joint between the two groups.

Conclusion: There were no significant differences in the clinical outcome after three years when comparing magnesium versus a titanium screw. Limitations of the study included not being able to do x-rays on asymptomatic patients to correlate them with the clinical and MRI findings after three years due to radiation exposure. Another limitation included not performing a preoperative MRI or early follow-up MRIs, which limited the study's ability to see the evolution of bone healing. The only advantage that was found with magnesium implants was having less artifacts in imaging.

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