Low back pain influences medial-lateral trunk movement variations during sit-to-stand tasks in persons with transtibial amputation

Background: Individuals with lower-limb amputation commonly experience low back pain, which may be associated with altered movement strategies or impaired trunk control during activities of daily living, such as sit-to-stand. The aim of this study was to assess, using wearable sensors, sit-to-stand performance and trunk movement variations of persons with transtibial amputation, with and without low back pain. Methods: Fifty-eight persons with unilateral transtibial amputation (28 with and 30 without low back pain) performed five sit-to-stand trials while wearing two inertial measurement units affixed to the thigh and sternum. Sit-to-stand completion time, as well as triaxial root mean square of acceleration and triaxial variance of jerk (calculated from the trunk sensor), were compared between groups. Findings: There was no difference in completion time between groups (12.1 ± 3.8 vs 11.6 ± 2.9 s; p = 0.54), but there was greater movement variation for persons with vs. without low back pain in the medial-lateral direction (p = 0.042), including root mean square of acceleration for sit-to-stand (p = 0.049) and variance of jerk for sit-to-stand (p = 0.012) and stand-to-sit (p = 0.018). Interpretation: This study indicates that accelerometer-based metrics of trunk control are able to differentiate between persons with transtibial amputation with and without low back pain, with the pain group demonstrating decreased control. The use of sensors may help guide in-clinic or at-home movement retraining or device prescriptions for improving trunk control during dynamic activities, such as sit-to-stand.