Early Axial Interfragmentary Motion and its Impact on the Fracture Healing Environment: A Scoping Review

dc.creatorRechter, Griffin
dc.creatorAnthony, Ryan
dc.creatorRennard, Justin
dc.creatorKellam, James
dc.creatorWarner, Stephen
dc.creator.orcid0000-0002-0218-5024 (Rechter, Griffin)
dc.description.abstractPurpose: The initial interfragmentary motion (IFM) at a fracture site determines the mode of fracture healing. Controlled axial IFM is thought to promote successful fracture healing, however the effects of minimal and excessive IFM can be detrimental to osteogenesis. Understanding the consequences of altering the fracture environment is important to advance our comprehension of fracture healing and has implications for surgical interventions. This review aims to consolidate information from the literature to assess our understanding of the effects of early axial IFM on fracture healing outcomes. Methods: PubMed and Medline databases were queried to identify studies from inception until June 2021 assessing axial IFM on fracture healing outcomes. 4,972 studies were initially identified. Following recommendations from PRISMA guidelines, two independent reviewers screened all studies, and data was extracted into a standardized spreadsheet. All outcome measures were recorded, including histomorphometric and radiographic analysis of the callus, biomechanical testing of callus strength, and time to union. Data synthesis is presented as a narrative review of our findings. Results: Fifteen studies met inclusion criteria totaling 605 fractures and osteotomies in skeletally mature participants. 423 animal and 182 human subjects were examined. Nine studies investigated IFM at the tibia, 4 at the metatarsus, and 2 at the femur. The gap size did not exceed 6mm in any study. The range of IFM in investigated tibias, metatarsi, and femurs was 0.32-2.0mm, 0.1-2.4mm, and 0.03-1.0mm, respectively. The median time to analysis was 9 weeks. Notable findings included no statistically significant association between early IFM and healing outcomes in experimental femur studies. All experimental tibial studies showed positive effects on callus formation with small-to-moderate axial IFM. Most studies found that allowing early micromovement produced superior callus stiffness and rigidity compared to rigid fixation, however continuing to increase the IFM negatively impacted biomechanical outcomes despite producing a larger callus. While increasing IFM often led to an enlarged callus size, the callus quality was compromised. Conclusions: The range of initial axial IFM conducive to a favorable fracture healing environment remains elusive. Preliminary evidence suggests an association between small-to-moderate initial axial IFM for stimulating successful fracture healing. However, heterogeneity in results and methodology precluded meta-analysis and comparability amongst studies. The cumulative evidence in the literature is insufficient to determine a definite correlation between the axial IFM and fracture healing outcomes. Future research should be directed at controlled trials and investigation of human subjects to understand the implications of orthopedic interventions on fracture healing outcomes.
dc.titleEarly Axial Interfragmentary Motion and its Impact on the Fracture Healing Environment: A Scoping Review