ABSTRACT
From March 1990 to February 1992, 40 cases of lumbar spondylolisthesis underwent transpedicle fixation and fusion using VSP system and PWB system. The diagnosis were isthmic types in 17 cases(male;9, female;8) and degenerative types in 23 cases(male;5, female;18), ranging in ages from 34 to 68 years with a mean age of 52 years. The preoperative slip measured less than 20% in 11 cases, between 20 and 40% in 27 cases and more than 40% in 2 cases. At an average 19 months follow up(range;9~33months), the degree of slip correction averaged 43% in isthmic group, 51% in degenerative group, a solic fusion based on radiologic evaluation was achieved in 85%. Overall results showed 77% good, 18% fair and 5% poor. Complications included superficial infection in 2 cases, screw breakage in 1 case and screw loosening in 2 cases.