Is the Control of Applied Digital Forces During Natural Five-digit Grasping Affected by Carpal Tunnel Syndrome?

Force Control Strategy of Five-Digit Precision Grasping With Aligned and Unaligned Configurations

OBJECTIVE

To investigate the digit force control during a five-digit precision grasp in aligned (AG) and unaligned grasping (UG) configurations.

BACKGROUND

The effects of various cylindrical handles for tools on power grasp performance have been previously investigated. However, there is little information on force control strategy of precision grasp to fit various grasping configurations.

METHOD

Twenty healthy young adults were recruited to perform a lift-hold-lower task. The AG and UG configurations on a cylindrical simulator with force transducers were adjusted for each individual. The applied force and moment, the force variability during holding, and force correlations between thumb and each finger were measured.

RESULT

No differences in applied force, force correlation, repeatability, and variability were found between configurations. However, the moments applied in UG were significantly larger than those in AG.

CONCLUSION

The force control during precision grasp did not change significantly across AG and UG except for the digit moment. The simulator is controlled efficiently with large moment during UG, which is thus the optimal configuration for precision grasping with a cylindrical handle. Further research should consider the effects of task type and handle design on force control, especially for individuals with hand disorders.

APPLICATION

To design the handle of specific tool, one should consider the appropriate configuration according to the task requirements of precision grasping to reduce the risk of accumulating extra loads on digits with a cylindrical handle.

The effectiveness of mobilization with movement on patients with mild and moderate carpal tunnel syndrome: A single-blinded, randomized controlled study

STUDY DESIGN

Single-blinded, randomized controlled study.

INTRODUCTION

Carpal Tunnel Syndrome (CTS) causes pain and loss of function in the affected hand. The mobilization with movement (MWM) technique is a manual therapy method applied to correct joint movement limitation and to relieve pain and functional disorders.

PURPOSE OF THE STUDY

This study aimed to examine the effectiveness of MWM technique on pain, grip strength, range of motion, edema, hand reaction, nerve conduction, and functional status in patients with CTS.

METHODS

A total of 45 patients enrolled in the study. The MWM group (n = 18) completed a 4-week combined conservative physiotherapy and MWM program, whereas the control group (n = 18) received only the 4 weeks of conservative physiotherapy. Pain severity according to the numerical rating scale was used as primary outcome.

RESULTS

We found an improvement within the subjects in resting pain (MWMG:5.1 ± 3.6 vs 1.1 ± 2.4, Effect Size (ES)=1.3; CG:4.5 ± 3.3 vs 1.0 ± 2.2, ES=1.1), in activity pain (MWMG:6.5 ± 3.7 vs 1.1 ± 2.4, ES=1.5; CG:4.8 ± 3.4 vs 2.2 ± 2.3, ES=1) and in night pain (MWMG:5.9 ± 3.2 vs 1.8 ± 2.5, ES=1.2; CG:5.3 ± 4.2 vs ± 2.3 ± 3.5, ES=0.9). For between the groups, a statistical difference was found for the activity pain, Disabilities of the Arm Shoulder and Hand Questionnaire score (MWMG:52.2 ± 23.8 vs 27 ± 24.7, ES=1.3; CG:47.0 ± 24.8 vs 41.5 ± 22.1, ES=0.2), Michigan Hand Outcomes Questionnaire (MHQ-1), (MWMG:44.4 ± 23.7 vs 74.7 ± 24.5, ES=1.3; CG:44.8 ± 17.4 vs 57.4 ± 21.7, ES=0.9) and MHQ-5 (MWMG:68.8 ± 13.1 vs 82.5 ± 11.5, ES=0.9; CG:63.4 ± 26.7 vs 59.3 ± 25.8, ES=0.1) parameters in favour of MWM group.

DISCUSSION

This study showed that MWM compared to conservative physiotherapy might be more effective in reducing perceived symptoms in mild and moderate CTS patients.

CONCLUSIONS

MWM produced a small benefit to recovery of activity pain and upper extremity functionality level outcomes of patients with mild to moderate CTS when added to a traditional CTS physical therapy program.

Externally applied force helps reduce bowstring effect of flexors in patients with carpal tunnel release surgery

BACKGROUND

Patients with severe carpal tunnel syndrome (CTS) undergo carpal tunnel release (CTR) surgery to alleviate pressure in the carpal tunnel. However, the subsequent lack of the transverse carpal ligament (TCL) causes the bowstring phenomenon of the flexor tendons and increases the potential incidence of trigger finger.

OBJECTIVE

This study aimed to investigate the effects of various compressive forces on the flexor tendon and identify the appropriate force needed to mitigate the bowstring effect of those flexors.

DESIGN

Cross-sectional repeated measures comparison.

METHOD

Thirteen CTS patients who underwent CTR surgery were asked to flex the middle finger while applying different external compressive forces, just contact, 4N, and 8N force, over the carpal tunnel. Images of the flexor tendon within the carpal tunnel and at the metacarpal phalangeal (MCP) joint were recorded via ultrasound.

RESULT

Results show that the compression force limited the volar migration of the flexor tendon under maximal voluntary contraction (MVC) conditions. Entrance angles between the flexor tendon and metacarpal bone also decreased as the external compressive force increased.

CONCLUSIONS

Findings of this study may indicate that applying compression force on the carpal tunnel is useful for CTS patients and can inhibit the volar shift of the flexor digitorum superficialis (FDS) tendon after surgery, which may further prevent trigger finger.

A Detailed Comparison of Preoperative Complaints in Severe Carpal Tunnel Syndrome versus Recurrent Carpal Tunnel Syndrome Using the Boston Carpal Tunnel Questionnaire

Background: The Boston Carpal Tunnel Questionnaire (BCTQ) has a symptom severity scale (SSS) with 11 questions and a functional status scale (FSS) with 8 questions. The final score for each scale is the sum divided by the number of questions and ranges between 1 and 5. A score of 1 indicates they have no complaints and 5 indicates high severity and functional loss. Unfortunately, this single digit score does not permit a detailed analysis of the symptoms and functional status. The aim of this study is to conduct an in-depth comparison of preoperative complaints using the BCTQ between patients with severe carpal tunnel syndrome (SCTS) and recurrent carpal tunnel syndrome (RCTS). Methods: This is a retrospective cohort study on the preoperative status of 37 patients with SCTS and 18 patients with RCTS using the BCTQ. The questions in the SSS and FSS were classified into four groups based on the responses of patients, namely a low complaint (LC) (1-1.99), moderate complaint (MC) (2-2.99), high complaint (HC) (3-3.99), and severe complaint (SC) (4-5) groups. The patients in the SCTS and RCTS groups were compared to find differences in age, gender, hand dominance, and responses to questions in the SSS and FSS. Results: The age of patients in the SCTS group (76.06 years) was significantly higher compared to the RCTS group (51.11 years). There was no significant difference between the two groups with regard to gender or hand dominance. The top question with SC or HC response in the SCTS group was problems in grasping small objects (SSS) and fastening buttons (FSS) and in the RCTS group was tingling in the hand (SSS) and difficulty with opening a jar (FSS). Conclusions: An in-depth analysis of the BCTQ allowed us to compare and understand differences in symptoms and function between patients with SCTS and RCTS. Level of Evidence: Level III (Therapeutic).

Maximum Palmar Abduction Angle of the Trapeziometacarpal Joint in Healthy Subjects Can Be Evaluated Accurately Using a Radiograph-Based Measurement Technique

In carpal tunnel syndrome, the abductor pollicis brevis, which is the primary muscle for the palmar abduction of the thumb, is almost inevitably impaired. The active palmar abduction of the thumb may be a better indicator of thumb disability. The authors aimed to establish a simple and accurate method to measure the angle of active palmar abduction of the thumb and to determine the maximum angle values in healthy women. Twenty-five women 20 to 21 years old with no disorder of the hand participated in this study voluntarily. Three measurement methods were tested. The first method was designed according to the Japanese Orthopaedic Association and the second method was designed according to the American Society of Hand Therapists; both use photographs to perform measurement calculations. In the third method, 2 orthopedic surgeons measured the same angle as that described in the second method on hand radiographs. Intra- and interobserver reliability were assessed for each method and described as interclass correlation coefficients. The first and third methods had strong inter- and intraobserver reliability. The second method had strong intraobserver reliability but medium interobserver reliability. The measurement obtained with the first method was significantly different from the values obtained by the second and third methods (almost double). Therefore, the authors regarded the third method as the most appropriate approach for measuring active palmar abduction of the thumb, which, in healthy individuals, yielded maximum values of 45.3°±6.4° and 44°±7° for the left hand and the right hand, respectively. [Orthopedics. 2020; 43(2):e95-e101.].

Quantification of weakness caused by distal median nerve lesion by dynamometry

INTRODUCTION

In the assessment of hand and upper limb function, grip strength is of major importance. Use of the JAMAR dynamometer has been an accepted test of grip strength and routinely part of the physical examination.

PURPOSE OF THE STUDY

The aim of this study was to determine by means of a median nerve block simulating a patient group if the measurement of different types of grip force can improve the quantification of impairment of the hand beyond the sole power grip measurements.

METHODS

In 29 healthy volunteers, grip force measurement was done by the JAMAR dynamometer for power grip and by a pinch grip dynamometer for pincer grip, precision grip, pinch grip, and palmar abduction. At the power grip, the force of digit 2-5 was measured separately by a sensor glove. For each measurement, 3 trials were recorded subsequently.

STUDY DESIGN

A within-subject research design was used in this prospective study. Each subject served as the control by preinjection measurements of grip and pinch strength. Subsequent measurements after median nerve block were used to examine within-subject change.

RESULTS

In power grip, there was no significant reduction of maximum grip force with median nerve block compared with grip force without block. By measuring the finger forces by a sensor glove, a reduction of force at the individual fingers was found compared with the setting with no block, although significant only at the middle finger (P < .017). With median nerve block, average grip force decreased significantly 20% in pincer grip (P < .021), 29.5% in pinch grip (P < .002), 39.5% in precision grip (P < .001), and 70.7% in palmar abduction (P < .013).

CONCLUSIONS

These experiments suggest a minor role of the measurement of the power grip force in the diagnostics of distal median nerve block with the dynamometer, which could not be substantially improved by the digit forces and the force distribution of the individual fingers. The assessment of other grip forms, such as pincer grasp, precision grip, pinch grip, and especially palmar abduction, leads to a relevant improvement in the diagnostics of distal median nerve lesion.

LEVEL OF EVIDENCE

II.

Force distribution of a cylindrical grip differs between dominant and nondominant hand in healthy subjects

INTRODUCTION

Grip strength and load distribution of the hand are important parameters for evaluating hand function. The purpose of this study was to analyze and compare grip force and load distribution of dominant and nondominant hands in right-handed healthy subjects.

METHODS

Gripping measurements were performed on 40 healthy right-handed subjects using a cylindrical gripping device. Two different cylinders with circumferences of 150 mm (small cylinder) and 200 mm (large cylinder), respectively, were used for the measurements. Subjects were assigned to either the small or the large cylinder with respect to their hand size. Maximum and mean force applied during three intervals of gripping as well as the percent contribution of each digit, thenar, and hypothenar in relation to the total load applied were acquired. Values of dominant and nondominant hands were compared.

RESULTS

Percent contribution of mean grip strength differed for the thumb (p = 0.007), ring finger (p < 0.001), little finger (p = 0.047), and palm (p < 0.001). Comparing the dominant and nondominant side, the dominant hand showed a lower contribution of the thumb, ring finger, and little finger, but a higher contribution of the palm. When analyzing maximum grip, percent contribution of the small fingers was equal between dominant and nondominant side (p = 0.1). Differences between dominant and nondominant thumb, ring finger, and palm persisted (p = 0.007, p = 0.001, p = 0.005, respectively). No differences could be shown for the index finger, middle finger, thenar, and hypothenar when analyzing both mean and maximum force.

DISCUSSION AND CONCLUSION

Percent contribution of the thumb and the fingers to total grip strength differed between dominant and nondominant hands with a change in distribution when assessing maximum grip force. In right-handed subjects, thumb and ring finger have important roles during gripping.

Grip force control and hand dexterity are impaired in individuals with diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN) affects the sensory function of the hands and, consequently, may negatively impact hand dexterity, maximum grip strength (GS_Max), and hand grip force (GF) control during object manipulation. The aims of this study were to examine and compare the GF control during a simple holding task as well as GS_Max and hand dexterity of individuals with DPN and healthy controls. Ten type 2 diabetic individuals diagnosed with DPN and ten age- and gender-matched healthy controls performed two traditional timed hand dexterity tests (i.e., nine-hole peg test and Jebsen-Taylor hand function test), a GS_Max test, and a GF control test (i.e., hold a instrumented handle). The results indicated that individuals with DPN and controls produced similar GS_Max. However, individuals with DPN took longer to perform the hand dexterity tests and set lower safety margin (exerted lower GF) than controls when holding the handle. The findings showed that mild to moderate DPN did not significantly affect maximum hand force generation, but does impair hand dexterity and hand GF control, which could impair the performance of daily living manipulation tasks and put them in risk of easily dropping handheld objects.

Carpal tunnel syndrome impairs index finger responses to unpredictable perturbations

The fine-tuning of digit forces to object properties can be disrupted by carpal tunnel syndrome (CTS). CTS' effects on hand function have mainly been investigated using predictable manipulation tasks; however, unpredictable perturbations are commonly encountered during manual tasks, presenting situations which may be more challenging to CTS patients given their hand impairments. The purpose of this study was to investigate muscle and force responses of the index finger to unpredictable perturbations in patients with CTS. Nine CTS patients and nine asymptomatic controls were instructed to stop the movement of a sliding plate by increasing index finger force following an unexpected perturbation. The electrical activity of the first dorsal interosseous muscle and forces exerted by the index finger were recorded. CTS patients demonstrated 20.9% greater muscle response latency and 12.0% greater force response latency compared to controls (p<0.05). The duration of plate sliding was significantly different between groups (p<0.05); the CTS group's duration was 142.2±5.8ms compared to the control group's duration of 133.1±8.4ms. Although CTS patients had increased muscle and force response durations comparatively, these differences were not statistically significant. Findings from this study suggest CTS-induced sensorimotor deficits interfere with accurate detection, processing and response to unpredictable perturbations. These deficits could be accounted for at multiple levels of the peripheral and central nervous systems. Delayed and decreased responses may indicate inefficient object manipulation by CTS patients and may help to explain why CTS patients tend to drop objects.