Article

A retrospective study of clinical results of operative treatment
for degenerative lumbar scoliosis. OBJECTIVE: To determine the risk factors of
sagittal decompensation after long instrumentation and fusion to L5 or S1.
BACKGROUND DATA: Little is known about the risk factors for sagittal
decompensation, which was defined in this study as sagittal C7 plumb falling
anterior >8 cm from the posterosuperior corner of the sacrum. METHODS: Forty-five
patients (mean age: 64.4 year) with adult degenerative lumbar scoliosis were
reviewed retrospectively with a minimum 2 years. The mean number of levels fused
was 6.1 +/- 1.6 segments. The upper instrumented vertebra ranged from T9 to L2.
The lower instrumented vertebra was L5 and S1 in 24 and 21 patients,
respectively. RESULTS: Sagittal decompensation (SD) developed in 19 patients. The
most significant risk factors of SD were preoperative sagittal imbalance and high
pelvic incidence. The preoperative sagittal C7 plumb was more positive (67.9 mm)
in the decompensation group than in the balance group (37.0 mm) (P = 0.002).
There was a significant difference in pelvic incidence between 61.7 degrees in
the decompensation and 54.9 degrees in the balance group (P = 0.01). The
preoperative lumbar lordosis was hypolordotic in the decompensation group,
however, it was not found to be a risk factor. Pseudarthrosis was identified at
the lumbosacral junction in 5 patients, and 4 of them (80%) had SD. SD developed
in 55% of patients who had loosening of the distal screws and 50% of patients
with hypolordotic lumbar fusion. Distal adjacent segment disease was more likely
to cause SD than proximal adjacent segment disease. CONCLUSION: Sagittal
decompensation is common after long posterior instrumentation and fusion for
degenerative lumbar scoliosis. It is mostly associated with complications at the
distal segments, including pseudarthrosis and implant failure at the lumbosacral
junction. Restoration of optimal lumbar lordosis and secure lumbosacral fixation
is necessary especially in patients with preoperative sagittal imbalance and high
pelvic incidence in order to prevent sagittal decompensation after surgery.

Langue : ANGLAIS

Tiré à part : OUI