Objective: Low lumbar osteoporotic vertebral collapse (OVC) has not been well documented compared with OVC of the thoracolumbar spine. The differences between low lumbar and thoracolumbar lesions should be studied to provide better treatment. The aim of this study was to clarify the clinical and imaging features as well as outcomes of low lumbar OVC and to discuss the appropriate surgical treatment.
Methods: Thirty patients (10 men; 20 women; mean age 79.3 ± 4.7 years [range 70-88 years]) with low lumbar OVC affecting levels below L-3 underwent surgical treatment. The clinical symptoms, morphological features of affected vertebra, sagittal spinopelvic alignment, neurological status before and after surgery, and surgical procedures were reviewed at a mean follow-up period of 2.4 years.
Results: The main clinical symptom was radicular leg pain. Most patients had old compression fractures at the thoracolumbar level. The affected vertebra was flat-type and concave or H-shaped type, not wedge type as often found in thoracolumbar OVC. There were mismatches between pelvic incidence and lumbar lordosis on plain radiographs. On CT and MR images, foraminal stenosis was seen in 18 patients (60%) and canal stenosis in 24 patients (80%). Decompression with short fusion using a posterior approach was performed. Augmentations of vertebroplasty, posterolateral fusion, and posterior lumbar interbody fusion were performed based on the presence/absence of local kyphosis of lumbar spine, cleft formation, and/or intervertebral instability. Although the neurological and visual analog scale scores improved postoperatively, 8 patients (26.7%) developed postoperative complications mainly related to instrumentation failure. In patients with postoperative complications, lumbar spine bone mineral density was significantly low, but the spinopelvic alignment showed no correlation when compared with those without complications.
Conclusions: The main types of low lumbar OVC were flat-type and concave type, which resulted in neurological symptoms by retropulsed bony fragments generating foraminal stenosis and/or canal stenosis. For patients with low lumbar OVC, decompression of the foraminal and canal stenosis with short fusion surgery via posterior approach can improve neurological symptoms. Since these patients are elderly with poor bone quality and other complications, treatments for both OVC and osteoporosis should be provided to achieve good clinical outcome.
Keywords: BMD = bone mineral density; JOA = Japanese Orthopaedic Association; LL = lumbar lordosis; OVC = osteoporotic vertebral collapse; PI = pelvic incidence; PLF = posterolateral fusion; PLIF = posterior lumbar interbody fusion; PSF = pedicle screw fixation; PT = pelvic tilt; PTH = parathyroid hormone; SS = sacral slope; VAS = visual analog scale; VCR = vertebral column resection; VP = vertebroplasty; clinical feature; clinical outcome; low lumbar spine; osteoporotic vertebral collapse; surgery.