Quantifying Lumbar Mobilization With Inertial Measurement Unit.

OBJECTIVE: Lumbar mobilization is a standard intervention for the management of low back pain, yet ways to quantify lumbar mobilization are limited. An inertial measurement unit (IMU) is a small and inexpensive device that can be used to quantify lumbar mobilization. The objective of this study was to determine the validity and reliability of an IMU in measuring the amplitude of displacement of a clinician's hand movement during oscillatory lumbar mobilization. METHODS: An IMU was secured on a clinician's hand during application of mobilization forces at the L4 segment of 16 healthy participants. The validity of the IMU was tested against common laboratory methods of measurements (force plate and motion capture system). The reliability of the IMU measurements was determined between 2 clinicians (inter-rater reliability) and between 2 sessions (intra-rater reliability) by calculating percent error of measurement (%e) and limits of agreement (LOA). The reliability was considered high when |%e| ≤ 10% and |LOA| ≤ 20%; moderate when |%e| 10% to 20% and |LOA| 21% to 40%; and non-acceptable when |%e| > 20% and |LOA| > 40%. RESULTS: The IMU measurements had high correlation with the force plate measurements (rs = 0.94) and high agreement with the motion capture system measurements (%e = 4%, LOA = -11% and 20%). Both the inter-rater reliability (%e = 6%, LOA = -25% and 37%) and the intrarater reliability (%e = -1%, LOA = -29% and 27%) of IMU measurements were moderate. CONCLUSION: The IMU seems to be a valid device to measure the amplitude of a clinician's hand movement. The moderate reliability found in this study may not reflect poor reliability of the IMU as much as inconsistency in reapplication of lumbar mobilization.

Trunk Control Response to Unstable Seated Posture During Various Feedback Conditions in People with Chronic Low Back Pain.

AIMS: People with chronic low back pain (CLBP) tend to have altered postural control. Visual biofeedback may be used to restore postural control. The purpose of this pilot study was to investigate the effect of visual biofeedback on seated postural trunk control in subjects with CLBP, and to investigate the relationship between the postural control parameters and clinical tests. METHODS: Ten CLBP subjects (8 female, 2 male; age 40.6±5 yrs; BMI 25.06±2.93) and 10 healthy matched controls (8 female, 2 male; age 41.2±5.88 yrs; BMI 24.61±3.17) underwent seated postural assessment. Center of pressure (COP) parameters were collected under three experimental conditions: eyes-open, visual biofeedback, and eyes-closed. RESULTS: The results revealed that COP velocity was significantly different between healthy and CLBP subjects for each condition, both healthy and CLBP subjects had no differences in COP parameters between eyes-open and visual biofeedback conditions, and in subjects with CLBP, the straight leg raise clinical test had a strong negative correlation with all COP parameters. CONCLUSIONS: Our results suggest that 30-second visual biofeedback training did not improve the seated postural control of CLBP subjects, potentially due to the short duration of training, and that hamstrings muscle tightness or decreased sciatic nerve mobility was associated with worse postural control.