Predictive Factors for the Outcome of Surgical Treatment of Lumbar Spondylolysis in Young Sporting Individuals

STUDY DESIGN: Retrospective consecutive case series. OBJECTIVES: Only few sporting individuals with symptomatic lumbar pars injuries require surgical repair and it is often difficult to predict the outcome following surgery. The factors that predict the outcome after direct repair of lumbar pars defect was evaluated clinically and statistically. The preoperative background variables both subjective and objective as well as radiological evaluation were used in a multiple regression model to find the strong predictors of postoperative outcome as measured by VAS (visual analogue scores), ODI (Oswestry Disability Index) and SF-36 (Short Form). METHODS: Fifty-two consecutive young sporting individuals with a mean age of 19 years (range 8-30 years) were treated surgically for lumbar pars defect confirmed on imaging studies (ie, single-photon emission computed tomography, computed tomography, and magnetic resonance imaging). Fifty patients completed the VAS, ODI, and SF-36 questionnaires as a part of their assessment. Preoperative background variables were used in a multiple regression model to find the strongest predictor of postoperative outcome as measured by ODI. Ethical approval was taken by the institutional review board. RESULTS: Buck’s screw repair of the pars defect was carried out in 44 patients (33 males, 11 female): unilateral in 8 patients (7 males, 1 female) and bilateral in 36 patients (26 males, 10 females). Although age at surgery showed linear colinearity (ρ = 0.32, P < .05), it was not significant in the model. The most consistent association with the preoperative VAS score were the pre- and postoperative ODI scores, that is, ρ = 0.51 (P < .01) and ρ = 0.33 (P < .05), respectively. In the bilateral group, with Buck’s repair at a single level, that is, 33 of 36 (93%) patients had returned to sports at a mean time of 7.5 months (range 6-12 months). Overall, 44 of 52 (84%) individuals had returned to their sports with posttreatment ODI score of <10. The stepwise regression modeling suggested 6 independent factors (preoperative ODI, preoperative SF-36 physical component summary (PCS), Buck’s repair, multiple operations, professionalism, and pars defect at L3), as the determinants of the outcome (ie, postoperative ODI) in 80.9% patients (R(2) = 0.809). CONCLUSIONS: The outcome after direct repair of pars defect in those younger than 25 years runs a predictable course. Professionalism in sports has a high impact on the outcome. Preoperative ODI and SF-36 PCS scores are significant predictors of good functional outcome. The regression equation can predict the outcome in 80.9% sporting individuals undergoing Buck’s repair.