Knee misalignment and exercise amount: Predictive value for chronic low back pain in young competitive athletes

Sports medical examinations of juvenile athletes provide an opportunity for preventive measures against sports-related diseases. Determining the leg axis deviation as a risk factor for future constraints may offer approaches for such measures. Data were obtained from 789 youth athletes: 166 with coronal plane knee misalignment and 623 without. After a seven-year period, 64 participants (m: 33, f: 31) from both groups were reassessed for the incidence of nonspecific chronic low back pain (CLBP). To distinguish participants with increased risk for CLBP, contingency tables for comparison of expected and joint frequency distribution testing and receivers operating characteristic (ROC) analyses for the weekly training time were conducted. Subjects with an initial diagnosed knee misalignment showed increased risk for the development of CLBP (CHI² = 4.2, p < .05, OR = 3.4) compared to participants without knee misalignment. In athletes with knee misalignment, ROC analysis revealed an optimal cut-off of 6.75 h/w (AUC = 0.8; Chi² = 4.2, p < .05, OR = 8.0). In athletes without leg axis deviation, no association to training volume was detected. Our results suggest a predictive value of knee misalignment on the later occurrence of CLBP in young competitive athletes and underline the importance of an examination of the motor system during sports medical assessments in youth athletes. Training volume of almost more than 7 h a week enhances this risk.