LUMBOSACRAL FUSIONS WITH FEMORAL CORTICAL ALLOGRAFT RINGS

Aim of the study: To evaluate the midterm radiographic behaviour of fe morocortical allograftrings (FCA) in lumbosacral fusions in patients w ith disabling low back pain. Methods: The radiographs of 41 patients w ith a minimum follow-up of 2 years were analysed by an independent ort hopedic radiologist. The fusion rate was determined on lateral tomogra ms routinely obtained at 3 months intervals. On lateral radiographs th e posterior intervertebral disc height as well as the segmental lordos is were measured. Changes of the allograftring such as mottling, resor ption and incorporation were registered. Results: The fusion rate was 95,2%. Time to radiographic fusion averaged 8,7 months (2-34 months) a nd in 66,1% radiographic fusion occurred without significant subsidenc e. In 18,6% fusion with subsidence resulted from resorption of the FCA and in 15,3% the FCA had protruded into the vertebral body. The poste rior intervertebral disc height increased postoperatively by 1,9 milli meters on average. However, postoperative height loss was the rule and occurred within the first 12 postoperative months, resulting in a neg ligible final gain in height of 0,3 millimeters on average. The final gain in segmental lordosis was 1,3 degrees on average. Complete graft in corporation occurred in 16 of 62 segments (25,8%). Conclusion: The described technique has proven to be highly effective in achieving a h igh fusion rate with a stable midterm graft behaviour.