Predictors of walking ability after surgery for lumbar spinal canal stenosis: a prospective study

BACKGROUND CONTEXT: Few studies have investigated predictors of objective walking distance in patients with lumbar spinal stenosis (LSS). PURPOSE: This study aimed to clarify objective predictors of postoperative 6-minute walk distance (6MWD) in patients with LSS and to develop prediction equations. STUDY DESIGN: This was a prospective study. Data were analyzed by multiple linear regression analyses. PATIENT SAMPLE: Patients with LSS were enrolled. OUTCOME MEASURES: Predictors of 6MWD after surgery were evaluated, including patient characteristics (sex, age, height, and body weight), pain (visual analog scale; low back pain, lower limb pain, and lower limb numbness), surgical factors (number of operation segments [1 or >= 2], surgery type [fusion or decompression], and minimum area of the dural sac), and objective physical function (6MWD and trunk muscle strength). METHODS: Patients with LSS were consecutively included and assessed preoperatively (n=113) and 6 months postoperatively (n=78). Simple and multiple linear regression analyses were performed with 6MWD at 6 months postoperation as the dependent variable. We have study funding sources (Nagono Medical Foundation) and no study-specific conflicts of interest-associated biases. RESULTS: At 6-month follow-up, 6MWD (457.7 +/- 105.5 m) improved significantly compared with preoperative 6MWD (275.0 +/- 157.2 m; p<.01). Trunk muscle strength and pain improved significantly compared with the preoperative score (p<.01). The predictors of postoperative 6MWD were age, body weight, number of operation segments (1 or =2), surgery type (fusion or decompression), preoperative trunk extensor strength, and preoperative 6MWD (adjusted R-2 =0.65, p<. 01). The proposed prediction equation was as follows: postoperative 6MWD (m)=549.5-5.3x age (years)-1.8xbody weight (kg)-68.3xsurgery type (0: decompression, 1: fusion) -58.6xoperation segment (0: one segment, 1: >= 2 segments)+3.5xtrunk extensor strength (kg)+0.2xpreoperative 6MWD (m). CONCLUSIONS: Younger age, lower body weight, one level operative segment, decompression surgery, and better preoperative scores for trunk extensor strength and 6MWD predicted better scores for 6 months postoperative 6MWD. Preoperative reduction in body weight and increase of trunk extensor strength might be associated with improved postoperative 6MWD scores. (C) 2019 Elsevier Inc. All rights reserved.