Biomechanical Comparision And Clinical Evaluation Of Two Differenot Low Lumbar Fusion Methods

Objective: To compare biomechanical effect of the posterior lumbar interbody fusion (PLIF) and posterlateral fusion(FLF) in the management of instability of low lumbar spine, In the meantime, the clinical outcome of the two fusion methods on lumbar segmental instability was evaluated.Methods: Biomechanics test: The lumbar spines of 6 fresh cadaveric specimens from L4-L5 were obtained. The age at the time of death ranged from 28 to 51 years old. The average age is 39 years old. All specimens were evaluated radio-graphically before testing, to exclude occult malignant disease and to assess relative bone quality. The specimens were dissected with preservation of osteoligamentous structures. The spines were double-bagged and frozen at–20℃until the day of testing, and were kept moist with phosphate-buffered saline solution. The time of preservation is from 12 to 53 days with the average time of 31 days. The L4 and L5 vertebrae of all speciments were instrumented with pedicle screws(Moss Miamin, 8.5mm×45 mm). Pedicle screw placement was confirmed with anter- opsterior and lateral radiography. Two length of rods were contoured and fit to the pedicle crews to model L4-L5 posterior lateral fusion. Graded facetectomies and discectomy were made...