Peri-implant gas accumulation in response to magnesium-based musculoskeletal biomaterials: reframing current evidence for preclinical research and clinical evaluation.

Abstract

Historically, the rapid degradation and massive gas release from magnesium (Mg) implants resulted in severe emphysema and mechanical failure. With the advent of new alloys and surface treatment methods, optimized Mg implants have re-entered clinics since last decade with reliable performance. However, the optimization aims at slowing down the degradation process, rather than exemption of the gas release. This study involved a systematic evaluation of current preclinical and clinical evidence, regarding the physical signs, symptoms, radiological features, pathological findings and complications potentially associated with peri‑implant gas accumulation (PIGA) after musculoskeletal Mg implantation. The literature search identified 196 potentially relevant publications, and 51 papers were enrolled for further analysis, including 22 preclinical tests and 29 clinical studies published from 2005 to 2023. Various Mg-based materials have been evaluated in animal research, and the application of pure Mg and Mg alloys have been reported in clinical follow-ups involving multiple anatomical sites and musculoskeletal disorders. Soft tissue and intraosseous PIGA are common in both animal tests and clinical follow-ups, and potentially associated with certain adverse events. Radiological examinations especially micro-CT and clinical CT scans provide valuable information for quantitative and longitudinal analysis. While according to simulation tests involving Mg implantation and chemical processing, tissue fixation could lead to an increase in the volume of gas cavity, thus the results obtained from ex vivo imaging or histopathological evaluations should be interpreted with caution. There still lacks standardized procedures or consensus for both preclinical and clinical evaluation of PIGA. However, by providing focused insights into the topic, this evidence-based study will facilitate future animal tests and clinical evaluations, and support developing biocompatible Mg implants for the treatment of musculoskeletal disorders.