Surgical widening of a stress fracture decreases local strains sufficiently to enable healing in a computational model

Stress fractures at the tibial diaphysis are prone to delayed union. We hypothesized that the interfragmentary strains in the gap tissue are of magnitudes that prohibit bone formation and healing. If so, a rational treatment would be to widen the fracture gap in order to decrease the strains. This could be achieved by replacing part of the fracture crack with a wide drilled hole. This study analyzes the biomechanical effects of this potential treatment through computational modeling. Poroelastic finite element models of an intact tibia, a tibia with a stress fracture, and a tibia with a drilled stress fracture were developed from clinical CT images. Loads corresponding to gait and stair climbing were simulated. Stresses, strains, and fluid velocities were evaluated for the bone in the tibia, and for the hypothetical soft tissue that fills the stress fracture. A minor decrease in the overall tibial stiffness (<9.9%) was noted as a result of drilling. The models predicted large interfragmentary strains in the soft gap tissue (max 35%) before drilling, which decreased substantially (<1%) after drilling. Thus, when comparing to current mechanobiological tissue differentiation theories, the authors believe that fracture gap widening by drilling a hole might facilitate healing of stress fractures.

Grassi, LorenzoLund University,Lunds universitet,Avdelningen för Biomedicinsk teknik,Institutionen för biomedicinsk teknik,Institutioner vid LTH,Lunds Tekniska Högskola,Department of Biomedical Engineering,Departments at LTH,Faculty of Engineering, LTH(Swepub:lu)soli-glo (author)
Aspenberg, Per (author)
Isaksson, HannaLund University,Lunds universitet,Avdelningen för Biomedicinsk teknik,Institutionen för biomedicinsk teknik,Institutioner vid LTH,Lunds Tekniska Högskola,Department of Biomedical Engineering,Departments at LTH,Faculty of Engineering, LTH(Swepub:lu)soli-hai (author)
Avdelningen för Biomedicinsk teknikInstitutionen för biomedicinsk teknik (creator_code:org_t)

By the author/editor: Fågelberg, Emil; Grassi, Lorenzo; Aspenberg, Per; Isaksson, Hanna

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