Magnetic resonance imaging predictors of surgical outcome in degenerative lumbar spinal stenosis

To identify any MRI predictors for surgical outcomes of patients with degenerative lumbar spinal stenosis (DLSS) having instrumented posterior decompression (IPD) surgery.

Seventy patients with DLSS who underwent IPD were reviewed retrospectively. The clinical score of each patient was assessed using the JOAS (Japanese Orthopedics Association Scoring) system, which is mainly based on the subjective symptoms and physical signs of the patients before (JOAS-I) and after (JOAS-II) surgery. Healing rate (HR) was calculated as: [(JOAS-II) - (JOAS-I)] × 100/[15 - (JOAS-I)]. HR >50 % was considered clinical improvement. Radiological stenosis was assessed on MRI and was graded from 0 to 3 at the laminectomy level in terms of thecal sac-nerve root compression, foraminal stenosis, and facet degeneration.

Mean HR of the improved patients (n = 39) was 81.94; HR of the unimproved patients (n = 31) was 34.75 (p < 0.05). There was no statistical difference in radiological stenosis parameters between the two groups (p > 0.05). HR was worse in patients with severe facet degeneration.

Surgical outcomes of DLSS depend on multiple variables. It is not possible to predict the outcomes by assessing only one parameter. The possible outcomes should be analyzed by considering all the factors individually.