Worley ML, et al. - Authors gauged the correlation of anterolateral thigh osteomyocutaneous (ALTO) flap harvest, with and without prophylactic fixation, on femur structural integrity as measured by a 4-point bend and torsional biomechanical testing. Significant changes in the structural integrity of the femur were resulted by anterolateral thigh osteomyocutaneous flap harvest. Findings suggested a strong consideration of postoperative stabilization.

Methods

• Twenty four synthetic fourth-generation composite femurs with validated biomechanical properties at a research laboratory, underwent 10-cm-long, 30% circumferential osteotomies at the proximal middle third of the femur; 6 femurs served as controls.
• Torsional and 4-point bend biomechanical testing were carried out in osteotomized femurs with and without fixation.
• Intramedullary nail and distal interlock screw placement was consisted by femur fixation.
• They compared the force and torque to fracture (expressed in kilonewtons [kN] and Newton meters [N.m], respectively) between controls, osteotomized femurs without fixation, and osteotomized femurs with fixation.
• Femur stiffness and fracture patterns were included in the additional outcome measures.

Results

• Findings suggested that on posterior to anterior (PA) 4-point bend testing, force to fracture of osteotomized femurs was 22% of controls (mean difference, 8.3 kN; 95% CI, 6.6-10.0 kN).
• As per data, on torsional testing the torque to fracture of osteotomized femurs was 12% of controls (mean difference, 351.1 N.m; 95% CI, 307.1-395.1 N.m).
• After fixation there was a 67% improvement in PA force to fracture and a 37% improvement in torque to fracture.
• Nonetheless, results demonstrated that osteotomized femurs with fixation continued to have a reduced PA force to fracture at 37% of controls (mean difference, 6.8 kN; 95% CI, 4.5-9.2 kN) and torque to fracture at 16% of controls (mean difference, 333.7 N.m; 95% CI, 306.8-360.6 N.m).
• On torsional testing, similar spiral fractures through a corner of the distal osteotomy site were developed in all osteotomized femurs.
• They noted a change in this fracture pattern after prophylactic fixation with femurs developing nondisplaced fractures through the proximal osteotomy site.
• During testing of osteotomized femurs with fixation, there were no underlying hardware failures.