Validation of two-dimensional video-based inference of finger kinematics with pose estimation.

Accurate capture finger of movements for biomechanical assessments has typically been achieved within laboratory environments through the use of physical markers attached to a participant's hands. However, such requirements can narrow the broader adoption of movement tracking for kinematic assessment outside these laboratory settings, such as in the home. Thus, there is the need for markerless hand motion capture techniques that are easy to use and accurate enough to evaluate the complex movements of the human hand. Several recent studies have validated lower-limb kinematics obtained with a marker-free technique, OpenPose. This investigation examines the accuracy of OpenPose, when applied to images from single RGB cameras, against a 'gold standard' marker-based optical motion capture system that is commonly used for hand kinematics estimation. Participants completed four single-handed activities with right and left hands, including hand abduction and adduction, radial walking, metacarpophalangeal (MCP) joint flexion, and thumb opposition. The accuracy of finger kinematics was assessed using the root mean square error. Mean total active flexion was compared using the Bland-Altman approach, and the coefficient of determination of linear regression. Results showed good agreement for abduction and adduction and thumb opposition activities. Lower agreement between the two methods was observed for radial walking (mean difference between the methods of 5.03°) and MCP flexion (mean difference of 6.82°) activities, due to occlusion. This investigation demonstrated that OpenPose, applied to videos captured with monocular cameras, can be used for markerless motion capture for finger tracking with an error below 11° and on the order of that which is accepted clinically.

A study to compare strengths of cadaveric tendon repairs with round-bodied and cutting needles.

This human cadaver study investigated whether flexor tendon repairs performed with round-bodied needles had a higher risk of pull-out compared with those performed with cutting needles. Forty human cadaver tendons were repaired (20 with each type of needle), subjected to tensile traction testing and evaluated by failure load and mode of failure. The average failure load was 50 N (SD 13 N) for tendons repaired with round-bodied needles, compared with 49 N (SD 16 N) for tendons repaired with cutting needles. Round-bodied needles resulted in more suture pull-out (18 out of 20 tendons) than cutting needles (6 out of 20 tendons). We found no differences in failure load, but significant differences in the mode of failure between round-bodied and cutting needles when used for cadaveric flexor tendon repair.

Ligamentous constraint of the first carpometacarpal joint.

To examine the role of the ligaments in maintaining stability of the first carpometacarpal (CMC) joint, a sequential ligament sectioning study of sixteen specimens was performed. While a small compressive force was maintained, loads were applied to displace each specimen in four directions - volar, dorsal, radial, and ulnar. Translations of the specimen in both dorsal-volar and radial-ulnar axes were measured. Initially, the tests were conducted with the specimen intact. These tests were then repeated following sectioning of the CMC anterior oblique ligament (AOL), ulnar collateral ligament (UCL), intermetacarpal ligament (IML) and dorsal radial ligament (DRL). The first CMC joint translation was increased in the absence of IML and DRL (p < 0.05). Both IML and DRL were important in constraining the first CMC joint translation against external applied loads. Potential applications of these findings include the treatment of joint hypermobility and the reduction or delay of onset or progression of first CMC joint osteoarthritis.

Statistical shape modelling of the first carpometacarpal joint reveals high variation in morphology.

The first carpometacarpal (CMC) joint, located at the base of the thumb and formed by the junction between the first metacarpal and trapezium, is a common site for osteoarthritis of the hand. The shape of both the first metacarpal and trapezium contributes to the intrinsic bony stability of the joint, and variability in the morphology of both these bones can affect the joint's function. The objectives of this study were to quantify the morphological variation in the complete metacarpal and trapezium and determine any correlation between anatomical features of these two components of the first CMC joint. A multi-object statistical shape modelling pipeline, consisting of scaling, hierarchical rigid registration, non-rigid registration and projection pursuit principal component analysis, was implemented. Four anatomical measures were quantified from the shape model, namely the first metacarpal articular tilt and torsion angles and the trapezium length and width. Variations in the first metacarpal articular tilt angle (- 6.3° < θ < 12.3°) and trapezium width (10.28 mm < [Formula: see text] < 11.13 mm) were identified in the first principal component. In the second principal component, variations in the first metacarpal torsion angle (0.2° < α < 14.2°), first metacarpal articular tilt angle (1.0° < θ < 6.4°) and trapezium length (12.25 mm < [Formula: see text] < 17.33 mm) were determined. Due to their implications for joint stability, the first metacarpal articular tilt angle and trapezium width may be important anatomical features which could be used to advance early detection and treatment of first CMC joint osteoarthritis.