Maintenance of Disc Height and Lordosis When Performing a New Technique In Instrumented Lumbar Posterolateral Fusion - Results from a Consecutive Prospective Study

Study Design: Consecutive Prospective Study. Summary of Background Data: Lumbar fusion is considered the “gold standard” treatment for chronic low back pain (CLBP) that is believed to be due to degenerative disc disease (DDD) and is not relieved by prolonged conservative treatment. Instrumented intercorporal fusion is believed to restore disc height and prevent postoperative kyphosis better than instrumented posterolateral fusion (PLF). A new technique to perform PLF, using modern pedicle screw systems, challenges this belief. Objective: This study has two main objectives: to measure disc height and segmental lordosis pre-, post-, and late post-operative in patients operated on with a variant of PLF and to compare the results with reported measurements with other techniques. Material: The study included 97 consecutive patients (56 female) age 20-73, all with CLBP; 84 patients were diagnosed as DDD only, 13 patients had a spondylolisthesis with concurrent DDD. Forty-nine, patients were treated at one segment, 47 at two segments, and one patient at three segments. All patients were X-rayed preoperatively, immediately post-operative, and at late follow-up (≥ 10 months). Methods: In all patients, PLF’s were performed using a pretension-distraction technique. Disc height and lordosis were calculated for all treated segments according to evaluated methods. The values on disc height and lordosis were compared for each patient preoperatively, immediately post-operative, and at follow-up. Results: All treated segments had an increase of disc height at post-operative examinations. Despite some reduction of this increase at late control follow-up, the increase was still significant for L3-L4 segment (men) and L4-L5 and L5-S1 segments (women). Lordosis was reduced postoperatively with less than the measurement error for the method. Conclusions: When this method of PLF was used, long-term increase in disc height and maintenance of lordosis was as favorable as reported on intercorporal fusions.