Long Term Follow up Results of Threaded Fusion Cage(T.F.C.) in Surgical Treatment of Spondylolisthesis

The goal of operation in spondylolisthesis is improving radiculopathy and relieving lower back pain preventing further progression of the slip, through decompression of neural elements and fusion of spinal pseudoarthrosis, respectively. The author performed the posterior lumbar interbody fusion technique using a Threaded Fusion Cage(T.F.C.) for 41 patients as the surgical treatment for mild spondylolisthesis. All patients enrolled in the study were implanted with a T.F.C. at a single unstable level. We have investigated the outcome results for at least one year(mean 25.8 months). Of these patients 95% have shown solid fusions. Using the Prolo scale for economic and functional rating, the combined results of excellent, good score is 51%, but clinically symptomatic improvement is 66%. Therefore, posterior lumbar interbody fusion using T.F.C. was useful in treatment of mild degree spondylolisthesis.

A Clinical Analysis of Degenerative Supondylolisthesis

The auther has studied 60 patients of degenerative spondylolisthesis diagnosed and operatively treated at Hanyang University Hospital from January 1987 to June 1992, and analized the outcome. The results were summarized as followings: 1) Male to female ratio was 1:4, showing female predominance. Average peak ages were 5th and 6th decades. 2) "Pedicle-Facet Angle" and the degree of slipping had directly proportional relationship(Y=0.58X+110). The wider the angle is, the more slipping develops. 3) The significant symptom and sign were neurogenic intermittent claudication and negative straight-leg-raising test. 4) The degenerative spondylolisthesis developed most frequently at L4-5 level(74%), L5-S1(15%), L3-4(8%), 57 cases(95%) fell into Grade by Meyerding classification. 5) Complete or incomplete block on myelogram was present in 59%, and pseudodisc and lumbar spinal stenosis were noticed on CT. 6) Laminectomy with P.L.I.F. were done in 50 cases(83%) and total laminectomy and medial facetectomy and foraminotomy were done in only 4 cases(7%). In the comparision on the slipping degree before & after operation, in 55 cases(92%), slipping degrees showed no great change less than 2mm, but the almost showed exellent & good results. So we considered decom pression & fusion without excessive reduction was sufficient. 7) Threaded fusion cage(T.F.C) had the several benefits that 1) stability was good, 2) osteosynthesis through threaded was possible and 3) postoperative ambulation was possible earlier. Therefore recently, P.L.I.F. using T.F.C in the treatment of degenerative spondylolisthesis were used in many cases and further evaluation for T.F.C. should be considered.