INTERSPACE DISTRACTION AND GRAFT SUBSIDENCE AFTER ANTERIOR LUMBAR FUSION WITH FEMORAL STRUT ALLOGRAFT

The authors performed a retrospective review of 32 patients who had un dergone a single-level anterior lumbar fusion with femoral strut allog raft as an isolated procedure. The goal of the study was to use clinic al radiographs to measure interspace distraction, graft subsidence, in terspace collapse, the nature of allograft incorporation, and to corre late these results with successful arthrodesis. Results were categoriz ed according to plain radiographic appearance and flexion/extension st ability. Sixty-six percent of the group exhibited radiographic union w ith flexion/extension stability. Twenty-two percent exhibited stabilit y on the flexion-extension analysis but less than complete arthrodesis was present. Twelve percent exhibited radiographic non-union and flex ion-extension instability. Interspace distraction of 11 mm was obtaine d initially with a follow-up distraction of 5.5 mm. Graft subsidence w as noted posteriorly in 27 patients with an average subsidence of 4 mm . The authors' conclusions were: 1) Interspace distraction can be achi eved with anterior lumbar fusion if appropriate interbody grafts are u sed. 2) Despite a solid arthrodesis rate of only 66%, ''functional art hrodesis'' was achieved in 88%. In a retrospective review of patients who underwent anterior lumbar fusion with femoral strut allograft, int erspace distraction, graft subsidence, and incorporation and arthrodes is status were measured. A solid arthrodesis was achieved in 66% of th e patients, and functional arthrodesis in another 22%. Interspace dist raction was maintained in 59% of cases.