Relationship of Impaired Lumbar Spine-Hip Coordination During Sit To Stand and Stand To Sit with Functional Disability in Chronic Nonspecific Low Back Pain Patients

Background: This study aimed to investigate the relationships of lumbar spine-hip discoordination during sit-to-stand(STD) and stand-to-sit (SIT) with pain and functional disability in chronic nonspecific low back pain (CNLBP) patients.Methods: A cross-sectional observational study was conducted in a biomechanics laboratory of the physical therapydepartment located at the School of Rehabilitation Sciences, Iran University of Medical Sciences (Tehran–Iran). A totalof 16 CNLBP patients (men 9, female 7) aged 18–40 years (mean 31.48) were selected according to our eligibilitycriteria. Furthermore, ten reflective markers were placed on the spinous processes of T12 and S2, posterior andanterior superior iliac spines, greater trochanters, and lateral epicondyles. The patients were instructed to performSTD and SIT tasks at a preferred speed without using their hands. Relative phase angle was used as an indicator ofcoordination and was identified as the inverse tangent of angular displacement/angular velocity. Moreover, the relativephase angle between the lumbar spine and right and left hip joints was measured by subtracting the phase angle ofthe hip joint from the lumbar spine joint. The ratios of the total movements of the lumbar spine to the total movementsof the right and left hip joints were also calculated in the sagittal plane. Finally, Pearson correlation coefficients (r) wereutilized to assess the association between variables.Results: The results of this study indicated that kinematic parameters of the pain had statistically significant directrelationships with functional disability in CNLBP participants during STD and SIT with r values ranging from 0.57(Pvalue = 0.021) to 0.85 (Pvalue 0.001) and 0.54 (Pvalue=0.053) to 0.82 (Pvalue 0.001), respectively.Conclusion: Out of the results of this study, it could be stated that pain and functional disability play a major role inlumber spine-hip discoordination, and it altered the movement ratio in CNLBP patients during STD and SIT. In clinicalpractice, clinicians should improve lumber spine-hip discoordination in patients with CNLBP since there is a linearrelationship between kinematic parameters of the pain and functional disability in patients with CNLBP.Level of evidence: II