INTRODUCTION

      Symptoms left behind after spine surgery often hamper patients' activities of daily living and reduce their quality of life. However, most reports on residual pain after fusion surgery are based on surgery-related factors, and there have been few multidimensional studies. The purpose of this study was to investigate residual pain after fusion surgery for lumbar degenerative diseases in a multidimensional analysis.

METHODS

      The subjects were 232 patients (111 males and 121 females; mean age 67.7 years) who underwent posterior interbody fusion for lumbar degenerative diseases from 2012 to 2019 with no missing data. The preoperative diagnosis was degenerative spondylolisthesis (175 cases), foraminal stenosis (36 cases), and isthmic spondylolisthesis (21 cases). Outcome measures, including the Roland-Morris Disability Questionnaire (RDQ), the Japanese Orthopaedic Association back pain evaluation questionnaire (JOABPEQ), were used to evaluate preoperatively and at 6 months, 1 year, and 2 years postoperatively. The JOABPEQ is a disease specific QOL measure developed in Japan. Its validation study has been completed. It consists of five domains, including "body pain", "lumbar spine function", "locomotive function", "social disfunction", and "mentality". Higher the points, more favorable the results in JOABPEQ.

      The presence of residual pain was determined using the domain of “Body pain” in the JOABPEQ. In accordance with previous studies regarding the JOABPEQ, at 6 months postoperatively, those with improvement of 20 points or more compared to the preoperative score were defined as the improved group, and those with improvement less than 20 were defined as the residual group. Statistical analysis was performed using general linear regression to compare between groups, and before and after surgery. Statistical significance was defined as a p-value of less than 0.05.

RESULTS

      There were 66 patients in the residual group (30 females; mean age 69.7±8.6 years) and 166 patients in the improvement group (91 females; mean age 66.4±11.2 years). As a whole, RDQ and all domains of the JOABPEQ showed significant improvement postoperatively compared to preoperatively. RDQ and JOABPEQ "Body pain" were significantly higher in the preoperative residual group, compared with the improvement group. At 2 years postoperatively, the residual group demonstrated significantly lower values in RDQ and all domains of JOABPEQ than the improvement group.

DISCUSSION

            The residual group was preoperatively found to have less pain than the improvement group, but there was no significant difference in social disfunction and mentality between the groups. The results of this study showed that residual pain at 6 months postoperatively can be a predictive factor for poor prognosis, and it can affect the other domains of the JOABPEQ such as functional disability, social life, and psychological disability. Multidisciplinary pain management from the early postoperative period is important to further improve the outcome after lumbar fusion surgery.