[Biomechanical analysis of interespinous ligamentoplasty with polyester fiber after discectomy]

There are different pathologies of the lumbar spine that condition a biomechanical and clinical instability for its treatment, various stabilization techniques have been carried out that try to preserve the movement and the transmission of load of the affected segment such as the interspinatus ligamentplasty with Dallos® fiber.

To show the biomechanical variations of functional segment of lumbar spine of pigs, before and after performing the discectomy and ligamentoplasty with Dallos® fiber.

The lumbar segment was mounted in a servo-hydraulic multiaxial simulator. Mobility ranges of flexion, extension, lateral flexion and axial rotations were simulated under three conditions: 1. Natural segment, 2. Discectomy segment, and 3. Disectomized segment plus ligamentoplasty with Dallos® fiber. The mobility ranges are made up to a torque of 7.5 N-m The data of the torques and mobility ranges was collected in the simulator program and the results of the biomechanical changes between the three conditions described were plotted.

It was shown that lumbar biomechanics is affected after discectomy mainly in flexion and extension. In the left axial bending and rotation movements, an alteration of torque and mobility ranges was found.

The ligamentoplasty recovers part of the stability lost after discectomy preserving part of the disc height without reaching to equalize the movements as in the natural segment. After discectomy the distribution of force suggests that residual instability with ligament plasty may represent facet overload.