Pseudoarthrosis of vertebral fracture: radiographic and characteristic clinical features and natural history.

Background: We examined mobility based on radiographic appearance, clinical appearance, and the natural course of osteoporotic vertebral pseudoarthrosis (VPA) in a prospective study in 34 consecutive cases of VPA in 27 patients with osteoporosis.
Methods: Conventional lateral, lateral flexion, and extension stress radiography (XP) and supine cross-table lateral XP were performed. Anterior vertebral body height and vertebral kyphotic angle were measured to assess vertebral mobility. If vertebral cleft or vertebral instability, which means a difference in vertebral body height between conventional and supine cross-table lateral XP, was present, VPA was diagnosed. Back pain was classified into five grades.
Results: The average anterior vertebral height was 9.9 +/- 5.6 mm on conventional lateral XP; it increased to 11.4 +/- 6.5 mm on extension stress XP (not significant) and 18.3 +/- 5.7 mm on cross-table lateral XP (significant). The vertebral kyphotic angle was 24.1 degrees +/- 9.7 degrees on conventional lateral XP; it decreased to 21.6 degrees +/- 9.8 degrees on extension stress XP (not significant) and 11.8 degrees +/- 8.5 degrees on cross-table lateral XP (significant). Intravertebral clefts were detected by conventional lateral XP, extension stress XP, and supine cross-table XP in 3 of 34 (8.8%), 7 of 21 (33.3%), and 28 of 34 (82.4%) vertebral compression fractures (VCFs), respectively. Surgical treatment was performed in seven patients (two because of severe pain and five because of neurological deficits) and in one patient who died. Except in these eight patients, back pain decreased by at least one grade with time in 18 of 19 patients (95%) in whom the clinical course was analyzed. Radiographic follow-up using supine cross-table XP was performed in 15 of 19 patients. Although 11 of these 15 patients (73%) showed vertebral instability on supine cross-table lateral XP, 10 of 11 patients (91%) did not complain of intolerable back pain during daily activity at the final follow-up.
Conclusions: VPA is often detected on supine cross-table lateral XP but not usually on extension stress XP. Despite the presence of vertebral instability, many patients did not complain of intolerable back pain during their daily activity. Surgical treatment to alleviate back pain should be performed for painful VPA after conservative treatment for about 4 months.