title: Comparison of the failure biomechanics of spinal fixation devices.
abstract: The failure biomechanics of Harrington distraction rods, modified Weiss springs, and Luque rods were studied in intact cadavers and isolated spinal columns using flexion-compression loading. Most spines fractured at T-11 or T-12 at applied loads ranging between 556 and 4220 newtons (mean = 1833 N). After Harrington distraction rod placement, the same spines failed at a mean load of 859 N (42% of control), always as a result of hook extrusion and often including lamina fracture (seven cases). When modified Weiss springs were used, the spines failed at a mean load of 1128 N (54% of control) by allowing the spine to bend to the initial failure angle; in most instances, deformities resolved when the load was reduced. Luque rods were tested in four specimens; these provided the most rigid stabilization and failed at 83% of control values. Modified Weiss springs often maintain spinal stability better than Harrington distraction rods.
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006801:Humans; D008159:Lumbar Vertebrae / Q000293:injuries*; D008297:Male; D008875:Middle Aged; D009984:Orthopedic Fixation Devices / Q000592:standards*; D013904:Thoracic Vertebrae / Q000293:injuries*