Study Design
This study was a post-hoc subgroup analysis of prospectively collected data in the Spine Patient Outcomes Research Trial (SPORT).
Objective
Determine the risk factors for and to compare the outcomes of patients undergoing revision disc excision surgery in SPORT.
Summary of background data
Risk factors for reherniation and outcomes after revision surgery have not been well-studied. This information is critical for proper patient counseling and decision making.
Methods
Patients who underwent primary discectomy in the SPORT intervertebral disc herniation cohort were analyzed to determine risk factors for undergoing revision surgery. Risk factors for undergoing revision surgery for reherniation were evaluated using univariate and multivariate analysis. Primary outcome measures consisted of Oswestry Disability Index (ODI), the Sciatica Bothersomeness index (SBI), and the Short Form 36 (SF-36) at six weeks, three months, six months, and yearly to four years.
Results
Of 810 surgical patients patients, 74 (9.1%) received revision surgery for rehernation. Risk factors for reherniation included: younger age (HR 0.96 (0.94–0.99)), lack of a sensory deficit (HR 0.61 (0.37–0.99)) lack of motor deficit (HR 0.54 (0.32–0.91)) and higher baseline ODI score (HR 1.02 (1.01–1.03)). The time adjusted mean improvement from baseline to four years was less for the reherniation group on all outcome measures (BP 39.5 vs. 44.9, p=0.001; PF 37.1 vs. 44.5, p<0.001; ODI 33.9 vs. 38.3, p <0.001; SBI 8.7 vs. 10.5, p<0.001). At four years, only SBI (−9 vs. −11.4, p=0.002) was significantly lower in the reherniation group.
Conclusions
Younger patients with higher baseline disability without neurological deficit are at increased risk of undergoing revision surgery for reherniation. Those considering revision surgery for reherniation will likely improve significantly following surgery, but possibly not as much as with primary discectomy.