Outcomes in patients with minimal back pain undergoing prophylactic lumbar fusion for iatrogenic instability

For most patients undergoing lumbar fusion, back pain is a substantial part of their preoperative symptomatology. Occasionally, there are patients with minimal back pain in whom the extent of decompression required to treat leg symptoms requires a concomitant fusion to prevent postoperative instability. Although these patients may obtain relief of their leg pain, an additional concern is whether they will develop increased back pain after fusion. This study’s primary cohort comprised 1144 patients with complete preoperative and 2-year postoperative data including the Oswestry Disability Index (ODI), Short Form 36 (SF-36), and numeric rating scales (NRS) for back and leg pain. Thirty-nine patients with a preoperative back pain score of 3 or less were identified. Propensity scoring was used to match these patients to patients with moderate back pain (NRS 4-6) and severe back pain (NRS 7-10) based on demographics, baseline health-related quality of life, and surgical characteristics, resulting in 35 patients in each group. Paired t tests were used to determine within-group differences, and analysis of variance was used to determine between-group differences. A statistically significant improvement occurred in ODI, SF-36 Physical Component Summary, and NRS leg pain scores from preoperatively to 2 years postoperatively (P<.0001) within all groups; and a statistically significant improvement occurred in back pain scores in the moderate and severe back pain groups. No statistically significant change occurred in back pain from preoperatively to 2 years postoperatively (P=.528) in the minimal back pain group. Patients undergoing lumbar fusion for predominant leg pain with minimal back pain had acceptable outcomes, with no increase in back pain postoperatively.