Association between core stability and recurrence of lumbar spondylolysis in athletes

There is no report regarding the risk factor for recurrence of the lumbar spondylolysis. The purpose of this study was to reveal which physical characteristics relate to the recurrence of lumbar spondylolysis in athletes. A total of 59 patients, who participated in sports activities, were included in the study. They were divided into two groups: the recurrence group (RG) and the non-recurrence group (NRG). Physical characteristics of the straight leg raising angle (SLR), hip internal rotation angle (HIR), and Sahrmann Core Stability Test (SCST) of each group were investigated. The relationship between the physical characteristics of RG at return to sports and those at recurrence and the physical characteristics of NRG return to sports and those of RG at recurrence was statistically analyzed. SCST (mean ± SD) of the recurrence group (RG) at recurrence (1.3 ± 0.9) was significantly lower than at return to sports (2.7 ± 0.7, P = 0.0156), and also significantly lower than that of the non-recurrence group (NRG) at return to sports (3.0 ± 0.5, P = 0.001). The effect size (Cohen’s d) for this difference was 3.27, indicating a very large effect, although this may be an overestimation due to the small sample size. No significant differences were found in hip internal rotation (HIR) and straight leg raising (SLR) angles between RG at recurrence and both NRG and RG at return to sports. In a multivariable Firth-penalised logistic-regression model, the SCST level remained a highly significant independent predictor of recurrence (adjusted OR = 5.52, 95 % CI = 1.86–16.2, P = 0.002), whereas none of the other covariates reached statistical significance (P > 0.70). This study suggests that hypofunction of core stability may be associated with recurrence of lumbar spondylolysis in athletes. Core stability training might be beneficial as part of rehabilitation for athletes with lumbar spondylolysis.