Spine patient outcomes research trial: radiographic predictors of clinical outcomes after operative or nonoperative treatment of degenerative spondylolisthesis

Abstract

Study design: Subgroup analyses according to treatment received.

Objective: To evaluate whether baseline radiographic findings predicted outcomes in patients with degenerative spondylolisthesis.

Summary of background data: The spine patient outcomes research trial combined randomized and observational DS cohorts.

Methods: The Meyerding listhesis grade was determined on the neutral radiograph (n = 222). Patients were classified as having low disc height if disc height was less than 5 mm. Flexion-extension radiographs (n = 185) were evaluated for mobility. Those with greater than 10 degrees rotation or 4 mm translation were considered hypermobile. Changes in outcome measures were compared between listhesis (grade 1 vs. grade 2), disc height (low vs. normal), and mobility (stable vs. hypermobile) groups using longitudinal regression models adjusted for potential confounders. Outcome measures included SF-36 bodily pain and physical function scales, oswestry disability index (ODI), stenosis bothersomeness index, and low back pain bothersomeness scale.

Results: Overall, 86% had a grade 1 listhesis, 78% had normal disc height, and 73% were stable. Baseline symptom severity was similar between groups. Overall, surgery patients improved more than patients treated nonoperatively. At 1 year, outcomes were similar in surgery patients across listhesis, disc height, and mobility groups (ODI: grade 1 -23.7 vs. grade 2 -23.3, P = 0.90; normal disc height -23.5 vs. low disc height -21.9, P = 0.66; stable -21.6 vs. hypermobile -25.2, P = 0.30). Among those treated nonoperatively, grade 1 patients improved more than grade 2 patients (bodily pain + 13.1 vs. -4.9, P = 0.019; ODI -8.0 vs. + 4.8, P = 0.010 at 1 year), and hypermobile patients improved more than stable patients (ODI -15.2 vs. -6.6, P = 0.041; stenosis bothersomeness index -7.8 vs. -2.7, P = 0.002 at 1 year).

Discussion: Regardless of listhesis grade, disc height or mobility, patients who had surgery improved more than those treated nonoperatively. These differences were due, in part, to differences in nonoperative outcomes, which were better in patients classified as grade 1 or hypermobile.

Figure 1

Measurement techniques to determine translation (Fig.1A), intervertebral angle (Fig. 1B), and disk height (Fig. 1C). Anterior-posterior translation (T) was measured from the antero-inferior corner of the upper vertebra relative to the line of the anterior cortex of the lower vertebra and normalized to vertebral depth (D). The intervertebral angle (A) was measured between the inferior endplate of the upper vertebra and the superior endplate of the lower vertebra. Disk height was calculated as the average of the distance from the midpoint of the inferior endplate of the upper vertebra to its perpendicular intersection with the superior endplate of the lower vertebra (H₁) and of the distance from the midpoint of the superior endplate of the lower vertebra to its perpendicular intersection with the inferior endplate of the upper vertebra (H₂).