Cadaveric biomechanical analysis of insufficiency fracture fixation techniques.

Current techniques for insufficiency fracture repair restore prefracture strength and all potentially have the complication of cement extrusion. There is no information directly comparing different techniques. The study's purpose is to compare four techniques for vertebral body insufficiency fracture repair by analyzing restoration of height, strength, stiffness, and quantifying cement leakage. Four osteoporotic/osteopenic fresh cadaveric spines (T6-L5) vertebral bodies were divided into the four groups and by levels (thoracic, thoraco-lumbar, lumbar). They were compressed to 25% of their initial height to simulate compression fractures. The bones were fixed using Vertebroplasty, Osteoplasty (Interpore Cross International, Irvine, CA), Cavity Creation System (Synthes, Paoli, PA), or Kyphoplasty (Kyphon, Sunnyvale, CA). Pre- and post-treatment height, strength and stiffness were measured. Cement leakage was significant if >1 mL leaked into the spinal canal, endplate or periphery. Analysis of data was done using ANOVA. Strength was not significantly different between the techniques. All spine levels were significantly stronger post-fixation versus initially (P < 0.05). For each spine level and all levels combined, there was no significant difference in height restoration between techniques. Stiffness was significantly different in the lumbar levels between initial and post-fixation measurements (P < 0.05). There was no difference in stiffness at other levels or between fixation techniques. Cement extrusion was significant for L4 of the vertebroplasty group. It leaked 1 mL in the anterior periphery. The four fixation techniques were equal in restoring strength and stiffness. No difference was seen in height restoration. The lumbar levels decreased stiffness post-fixation may be due to using less cement than required to re-approximate initial stiffness. Cement extrusion was significant in only one vertebral body. This may be attributable to the small quantity of cement used for fixation. Overall, the three techniques were equal in restoration of height, strength and stiffness.

Heather McCann, MD, Matthew LePine, and John Glaser, MD. MUSC, Charleston, SC.