Quantitative Investigation of Hand Grasp Functionality: Thumb Grasping Behavior Adapting to Different Object Shapes, Sizes, and Relative Positions

This paper is the first in the two-part series quantitatively modelling human grasp functionality and understanding the way human grasp objects. The aim is to investigate the thumb movement behavior influenced by object shapes, sizes, and relative positions. Ten subjects were requested to grasp six objects ( 3 shapes × 2 sizes ) in 27 different relative positions ( 3 X deviation × 3 Y deviation × 3 Z deviation ). Thumb postures were investigated to each specific joint. The relative position ( X , Y , and Z deviation) significantly affects thumb opposition rotation (Rot) and flexion (interphalangeal (IP) and metacarpo-phalangeal (MCP)), while the object property (object shape and size) significantly affects thumb abduction/adduction (ABD) motion. Based on the F value, the Y deviation has the primary effects on thumb motion. When the Y deviation changing from proximal to distal, thumb opposition rotation (Rot) and flexion (IP and MCP joint) angles were increased and decreased, respectively. For principal component analysis (PCA) results, thumb grasp behavior can be accurately reconstructed by first two principal components (PCs) which variance explanation ratio reached 93.8% and described by the inverse and homodromous coordination movement between thumb opposition and IP flexion. This paper provides a more comprehensive understanding of thumb grasp behavior. The postural synergies can reproduce the anthropomorphic motion, reduce the robot hardware, and control dimensionality. All of these provide a more accurate and general basis for the design and control of the bionic thumb and novel wearable assistant robot, thumb function assessment, and rehabilitation.

Soft Pneumatic Exoskeleton for Wrist and Thumb Rehabilitation

A huge population of the world is suffering from various kinds of disabilities that make basic daily activities to be challenging. The use of robotics for limb rehabilitation can assist patients to recover faster and reduce therapist to patient ratio. However, the main problems with current rehabilitation robotics are the devices are bulky, complicated, and expensive. The utilization of pneumatic artificial muscles in a rehabilitation system can reduce the design complexity, thus, making the whole system light and compact. This paper presents the development of a new 2 degree of freedom (DOF) wrist motion and thumb motion exoskeleton. A light-weight 3D printed Acrylonitrile Butadiene Styrene (ABS) material is used to fabricate the exoskeleton. The system is controlled by an Arduino Uno microcontroller board that activates the relay to open and close the solenoid valve to actuate the wrist. It allows the air to flow into and out of the pneumatic artificial muscles (PAM) based on the feedback from the sliding potentiometer. The mathematical model of the exoskeleton has been formulated using the Lagrange formula. A Proportional Integral Derivative (PID) controller has been implemented to drive the wrist extension-flexion motion in achieving the desired set-points during the exercise. The results show that the exoskeleton has successfully realized the wrist and thumb movements as desired. The wrist joint tracked the desired position with a maximum steady-state error of 10% for 101.45ᵒ the set point.

Consequences of Untreated Pediatric Trigger Thumb: Case Report

Pediatric trigger thumbs present a conundrum for hand surgeons. Surgery for trigger thumbs has inherent risks, such as infection, nerve injury, and the risks of anesthesia, but will reliably solve the problem. But is surgical intervention necessary? Would these cases resolve spontaneously, eventually, without intervention? If not, what are the long-term consequences of the inability to fully extend the thumb interphalangeal joint? We present a pediatric trigger thumb that was symptomatic for 22 years, with complete resolution of symptoms after surgical intervention. This report illustrates at least some pediatric trigger thumbs will not resolve without surgical intervention, but treatment, even after 21 years, can result in normal thumb motion and function.

The Accuracy of a Screening System for Carpal Tunnel Syndrome Using Hand Drawing

When carpal tunnel syndrome (CTS), an entrapment neuropathy, becomes severe, thumb motion is reduced, which affects manual dexterity, such as causing difficulties in writing; therefore, early detection of CTS by screening is desirable. To develop a screening method for CTS, we developed a tablet app to measure the stylus trajectory and pressure of the stylus tip when drawing a spiral on a tablet screen using a stylus and, subsequently, used these data as training data to predict the classification of participants as non-CTS or CTS patients using a support vector machine. We recruited 33 patients with CTS and 31 healthy volunteers for this study. From our results, non-CTS and CTS were classified by our screening method with 82% sensitivity and 71% specificity. Our CTS screening method can facilitate the screening for potential patients with CTS and provide a quantitative assessment of CTS.

Three-dimensional analysis of thumb motion recovery after carpal tunnel release

This study quantified recovery of thumb motion in patients with carpal tunnel syndrome after carpal tunnel release using three-dimensional motion analysis with a retroreflective surface-based marker method. Eighteen hands from 14 patients who underwent carpal tunnel release for idiopathic carpal tunnel syndrome were included. The angular movements of the three joints of the thumb, the path length of the thumb tip and the area enclosed by the perimeter path of the thumb tip were measured during circumduction. The range of joint movement, including abduction/adduction of the trapeziometacarpal joint, and flexion/extension of the interphalangeal and metacarpophalangeal joints and the path length of the thumb tips, improved significantly 1 year after surgery. The quantification of thumb kinematics helps to better understand motor dysfunction in carpal tunnel syndrome, assess the severity of the condition and decide on treatment. Level of evidence: IV

Device Development for Detecting Thumb Opposition Impairment Using Carbon Nanotube-Based Strain Sensors

Research into hand-sensing is the focus of various fields, such as medical engineering and ergonomics. The thumb is essential in these studies, as there is great value in assessing its opposition function. However, evaluation methods in the medical field, such as physical examination and computed tomography, and existing sensing methods in the ergonomics field have various shortcomings. Therefore, we conducted a comparative study using a carbon nanotube-based strain sensor to assess whether opposition movement and opposition impairment can be detected in 20 hands of volunteers and 14 hands of patients with carpal tunnel syndrome while avoiding existing shortcomings. We assembled a measurement device with two sensors and attached it to the dorsal skin of the first carpometacarpal joint. We measured sensor expansion and calculated the correlation coefficient during thumb motion. The average correlation coefficient significantly increased in the patient group, and intrarater and interrater reliability were good. Thus, the device accurately detected thumb opposition impairment due to carpal tunnel syndrome, with superior sensitivity and specificity relative to conventional manual inspection, and may also detect opposition impairment due to various diseases. Additionally, in the future, it could be used as an easy, affordable, and accurate sensor in sensor gloves.

The Moovis® implant for trapeziometacarpal osteoarthritis: results after 2 to 6 years

In this retrospective study we reviewed the outcomes of 46 trapeziometacarpal joint replacements with the Moovis® prosthesis in 46 patients with painful osteoarthritis. The dual mobility design of this prosthesis aims to reduce prosthetic dislocation and subsidence. At follow-up 2 to 6 years (mean 5 years) after operation, pain was reduced from 6 to 0 on a visual analogue scale from 0 to 10. The scores of the Quick Disabilities of the Arm, Shoulder and Hand questionnaire improved significantly. Thumb motion and grip and pinch strength did not differ significantly from the contralateral hand. There were no radiographical signs of implant subsidence or loosening. No implant required revision. Forty-five patients rated the result as excellent or good. We conclude the Moovis® is a reliable and effective implant at short- to mid-term follow-up. Level of evidence: IV

Extensor pollicis longus rerouting for thumb-in-palm deformity in cerebral palsy: a biomechanical analysis

Extensor pollicis longus rerouting is a common procedure to improve thumb abduction in thumb-in-palm deformity seen with spastic cerebral palsy. In 1985, Manske redirected the extensor pollicis longus tendon in this procedure through the first extensor compartment. They also proposed an alternative subcutaneous route around the extensor pollicis brevis and abductor pollicis longus tendons proximal to the extensor compartment. In this study, we performed a three-dimensional analysis of thumb motion on 11 cadaver arms with the subcutaneous route and the first extensor compartment route. We found that with the two different routing methods, the mean difference in thumb radial abduction and retropulsion (0° or 6°, respectively) was very small. Such differences are unlikely to have clinical relevance. We were unable to find significant differences in the motion range of the thumb after these rerouting techniques or sites of insertion. Our biomechanical data support the simpler subcutaneous route.