Radiologic and Clinical Courses of Degenerative Lumbar Scoliosis (10°–25°) after a Short-Segment Fusion

STUDY DESIGN: Retrospective study. PURPOSE: We report the surgical outcomes of small degenerative lumbar scoliosis (DLS) patients treated by a short-segment fusion and followed for a minimum of 5 years. OVERVIEW OF LITERATURE: Several surgical options are available for the treatment of DLS, such as decompression only, decompression plus a short-segment fusion, or decompression with a long segment fusion. Few studies have evaluated the results of a short-segment fusion in patients with DLS over time. METHODS: Seventy small DLS patients (Cobb's angle, 10°–25°) with a minimum follow-up of 5 years were treated with a short-segment fusion between March 2004 and February 2010. The mean patient age was 71 (male:female=16:54), with a follow-up of 6.5 years (range, 5.0–11.6). The Cobb's angle, 1 and 2 segment coronal upper intervertebral angle, 1 and 2 segment sagittal upper intervertebral angle, the lumbar lordosis angle, and the C7 plumb lines (coronal and sagittal) were evaluated using simple radiographs, and visual analog scale (VAS), back pain was assessed preoperatively, immediately after surgery, and at 3, 6, and 12 months and 3 and 5 years after surgery. To identify factors influencing the radiologic progression, age, number of fusion segments, vertebral levels of fusion, body mass index, lowest instrumented vertebra (L5 or S1), bone mineral density (>–2.5, ≤–2.5), and the presence of an interbody fusion were analyzed. RESULTS: The Cobb's angle and 1 segment coronal upper intervertebral angle showed more progression during follow up, particularly at 6 and 12 months after surgery. Clinical outcomes and radiological results were found to be significantly associated (p=0.041). No statistically significant association was found between other factors affecting radiologic progression from postoperative 6 months to 1 year. CONCLUSIONS: Radiologic variables (the Cobb's angle and coronal upper intervertebral angle–1) should be carefully considered and clinical caution exercised from 6 to 12 months after short-segment fusion in small DLS (10°–25°).