To compare optical motion capture system (MoCap), attitude and heading reference system (AHRS) sensor, and Microsoft Kinect for the continuous measurement of cervical range of motion (ROM).
Fifteen healthy adult subjects were asked to sit in front of the Kinect camera with optical markers and AHRS sensors attached to the body in a room equipped with optical motion capture camera. Subjects were instructed to independently perform axial rotation followed by flexion/extension and lateral bending. Each movement was repeated 5 times while being measured simultaneously with 3 devices. Using the MoCap system as the gold standard, the validity of AHRS and Kinect for measurement of cervical ROM was assessed by calculating correlation coefficient and Bland–Altman plot with 95% limits of agreement (LoA).
MoCap and ARHS showed fair agreement (95% LoA<10°), while MoCap and Kinect showed less favorable agreement (95% LoA>10°) for measuring ROM in all directions. Intraclass correlation coefficient (ICC) values between MoCap and AHRS in –40° to 40° range were excellent for flexion/extension and lateral bending (ICC>0.9). ICC values were also fair for axial rotation (ICC>0.8). ICC values between MoCap and Kinect system in –40° to 40° range were fair for all motions.
Our study showed feasibility of using AHRS to measure cervical ROM during continuous motion with an acceptable range of error. AHRS and Kinect system can also be used for continuous monitoring of flexion/extension and lateral bending in ordinary range.
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To investigate the relationships between spinal mobility, pulmonary function, structural change of the spine, pain, fatigue, and quality of life (QOL) in patients with ankylosing spondylitis (AS).
Thirty-six patients with AS were recruited. Their spinal mobility was examined through seven physical tests: modified Schober test, lateral bending, chest expansion, occiput to wall, finger to ground, bimalleolar distance, and range of motion (ROM) of the spine. Pulmonary Function Test (PFT) was performed using a spirometer, and vertebral squaring was evaluated through the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). QOL, disease activity, functional capacity, and fatigue were evaluated by SF-36 Health Survey (SF-36), the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), the Bath Ankylosing Spondylitis Functional Index (BASFI), and the Multidimensional Assessment of Fatigue (MAF) scale, respectively. Perceived physical condition and degree of pain were assessed using 10 cm visual analogue scale.
Participants showed reduced spinal mobility, which was negatively correlated with mSASSS. PFT results showed reduced forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) and increased FEV1/FVC. Reduced FEV1 and FVC showed positive correlations with reduced spinal mobility and a negative relationship with mSASSS. Perceived physical condition and degree of pain were both significantly related to the SF-36, BASDAI, BASFI, and MAF scores.
This study shows that both reduced spinal mobility and radiographic changes in the vertebral body may have a predictive value for pulmonary impairment in patients with AS. Likewise, pain and perceived physical condition may play an important role in the QOL, functional capacity, and fatigue level of these patients.
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