New Proposal for the Treatment of Coronal Split Fractures in Lumbar Vertebrae: The Fatigue Curve

Abstract

Objective: To evaluate a new treatment for split fractures through fatigue tests on a swine model. Methods: Thirty lumbar spine samples (L2-L3-L4) from swine models were divided into three test groups. The first was the control group (intact vertebrae). In the second group, a bone defect was created, similar to a coronal split fracture of the vertebral body. For this, a bone defect (osteotomy) was performed in the coronal axis of the middle third of the middle lumbar vertebral body (L3), keeping the disc-ligament structures intact. In the third group, the same procedure was performed to cause bone failure, but was associated with the use of synthesis material, with pedicular fixation using 3.5 mm cannulated screws with partial thread, in order to apply compression at the fracture site, giving resistance and support to the vertebra. The groups were submitted to biomechanical fatigue tests. The number of cycles required to failure in the specimen was analyzed. Results: The use of the synthesis material increased the resistance of the fractured vertebrae to levels equal to those of the intact vertebra for low cycles with loads of 40% of the failure load, possibly losing up to 20% of their resistance for higher cycles. Conclusions: In the vertebrae in which synthetic material was used, greater resistance to a greater number of cycles for a longer period of time was observed when compared with the fractured vertebrae, suggesting that this is an interesting method for the fixation of split-type spinal fractures. Level of evidence III; Experimental Study.