One of the main functions of the human spine is to provide mechanical support to the body while allowing vari-ous degrees of motion. There are numerous lumbar pathologies that may cause instability. Although clinical experi-ence on large patient groups with fractures, infections, neoplasiae, scoliosis and spondylolisthesis has produced a vast amount of knowledge on the diagnosis and treatment of these disorders, clinical information is scarce on pri-mary and secondary degenerative instabilities. Between the years 1989-1993, fourteen patients (5 M, 9F) with pri-mary or secondary degenerative lumbar segmental instabilities were treated at the Marmara University School of Medicine, Department of Orthopaedics and Traumatoiogy. The patients were follovved up for clinical signs of heal-ing and radiological signs of stability for 23,8 months (mean 6-55 months). Eight cases healed completely, in three cases there was considerable improvement, in three cases there were various complaints in vvhich one had esta-blished pseudoarthrosis requiring revision.
Keywords: Functiona', Spine Unit, Segmental İnstability, Spinal Pseudoarthrosis.