Reliability of forearm medial-anterior surface dimensional changes at different isometric hand grip forces.

Indirect techniques of predicting hand grip force are fundamental to develop hand control systems for assistive devices. The purpose of this study was to determine the reliability of 3D position of forearm surface at different isometric hand grip forces. Three-dimensional motion analysis was used to measure displacement of 24 discrete and standardized surface markers placed on forearm in 20 healthy participants. The relative displacements were measured for isometric grip forces at 0%, 5%, 20% 50% and 80% of maximum voluntary contraction (MVC). Intraclass correlation coefficient (ICC) for relative radial displacement (RRD) of each marker was calculated. Averaged single measure ICC of 24 markers at five grip forces was 0.61; while the highest averaged single measure ICC (0.80) for all markers was achieved at 80% of MVC and the lowest (0.47) at 0% of MVC. The average measure ICC for each grip force across the 24 markers also increased with grip force from 0.80 at 0% of MVC to the maximum of 0.95 at 80% of MVC. In conclusion, RRD showed moderate and high ICCs for single and average measures respectively. Overall, this study suggests that the reliable dimensional changes of 3D positions of forearm surface might be considered as an indirect and non-invasive method to predict hand grip force in future.

Knee Kinematics and Joint Moments During Stair Negotiation in Participants With Anterior Cruciate Ligament Deficiency and Reconstruction: A Systematic Review and Meta-Analysis.

OBJECTIVE: Biomechanical changes have been reported for patients with anterior cruciate ligament deficiency (ACLD) and anterior cruciate ligament (ACL reconstruction) (ACLR), likely due to loss of stability and changes in proprioception and neuromotor control. This review evaluated kinematics and kinetics of ACLD and ACLR knees, compared with those on the contralateral uninjured sides, as well as and those in asymptomatic controls during stair navigation. DESIGN: This is a systematic review and meta-analysis. LITERATURE SURVEY: Electronic database searches were conducted from their original available dates to January 2015. Studies that included participants with ACLD or ACLR and reported knee joint angles or moments during stair ascent or descent were included. METHODOLOGY: Nine studies met the inclusion criteria, and the methodological quality of these was assessed with a modified Downs and Black checklist. Effect sizes for differences between injured leg and uninjured contralateral leg or controls were calculated, and meta-analyses were performed if two or more studies considered the same variable. SYNTHESIS: Quality assessment showed an average (± standard deviation) of 70.3% ± 7.2%. Meta-analysis showed less knee flexion at initial contact for ACLR knees compared with that in contralateral knees during stair ascent, with a moderate effect size and minimal heterogeneity. Knees with ACLD showed less peak knee flexion compared with that on contralateral sides during stair ascent, with minimal heterogeneity. External knee flexion moments were lower for ACLR compared with those in controls and contralateral sides during ascent and descent, whereas these moments were decreased for the ACLD compared with controls only during ascent. Meta-analysis results exhibited moderate/high heterogeneity or small/trivial effect sizes. CONCLUSIONS: Differences for kinematics and kinetics for the ACL-injured knees indicate long-term compensatory and asymmetric movement patterns while ascending and descending stairs. Due to the heterogeneity as well as the small numbers of available studies, the consequences of these differences in terms of long-term function or posttraumatic osteoarthritis need further exploration.

Intra-session and inter-day reliability of forearm surface EMG during varying hand grip forces.

Surface electromyography (EMG) is widely used to evaluate forearm muscle function and predict hand grip forces; however, there is a lack of literature on its intra-session and inter-day reliability. The aim of this study was to determine reliability of surface EMG of finger and wrist flexor muscles across varying grip forces. Surface EMG was measured from six forearm flexor muscles of 23 healthy adults. Eleven of these subjects undertook inter-day test-retest. Six repetitions of five randomized isometric grip forces between 0% and 80% of maximum force (MVC) were recorded and normalized to MVC. Intra- and inter-day reliability were calculated through the intraclass correlation coefficient (ICC) and standard error of measurement (SEM). Normalized EMG produced excellent intra-session ICC of 0.90 when repeated measurements were averaged. Intra-session SEM was low at low grip forces, however, corresponding normalized SEM was high (23-45%) due to the small magnitude of EMG signals. This may limit the ability to evaluate finer forearm muscle function and hand grip forces in daily tasks. Combining EMG of functionally related muscles improved intra-session SEM, improving within-subject reliability without taking multiple measurements. Removing and replacing electrodes inter-day produced poor ICC (ICC < 0.50) but did not substantially affect SEM.