Text neck is not associated with neck and upper limb disability in young adults who use smartphones

PURPOSE

The objective of the present study was to correlate neck and upper-limb disabilities with neck flexion in university students who are smartphone users. While handling smartphones, a posture with sustained neck flexion known as "Text Neck" is usually adopted, and some authors related to musculoskeletal symptoms on the neck and the upper limb. However, recent studies state that such an association is questionable.

METHODS

This is an observational study when evaluating 192 university students through questionnaires such as the Neck Disability Index (NDI), Disabilities of Arm, Shoulder, and Hand (DASH), besides the maximal neck flexion, grip and lateral pinch strength of the participants.

RESULTS

The sociodemographic questionnaire demonstrated that most participants had used the device for 5 to 10 years, for five or more hours per day. The DASH questionnaire scores presented an average of 7.2 points, while the data regarding grip and lateral pinch strength showed averages of 29.5 kgf and 8.8 kgf, respectively. The NDI questionnaire scores presented an average of 10.5. The average range of motion of the maximum neck flexion was 27°.

CONCLUSION

There was no association between neck flexion with the DASH and NDI or the grip and lateral pinch strength after the correlation and binary logistic regression analyses. The results show that the scores of DASH, NDI, hand grip and lateral pinch strength, have no association with the maximum neck flexion.

Movement analysis of the distal transverse arch of the dominant hand while grasping and pinching objects: A descriptive, correlational research study

BACKGROUND

The distal transverse arches obtained from active and passive motions of the hand and the used range of motion (u-ROM) of the hand arch in activities of daily living have rarely been reported.

PURPOSE

This study aimed to investigate the distal transverse arch angle of the dominant hand, the influence of age, and the u-ROM of the arch when grasping and pinching objects.

STUDY DESIGN

Descriptive and correlational research design.

METHODS

The active and passive distal transverse arches of the dominant hand of 104 healthy subjects were measured using a goniometer. Additionally, the hand arch was measured when the subjects grasped and pinched objects. These data were used to analyze the correlation with age and to calculate the u-ROM (u-ROM %) rate of the distal transversal arch. Furthermore, the u-ROM% between the ring and fifth finger components of the hand arch was compared.

RESULTS

The active and passive dorsal arch angles were 135.8 (10.0°) and 169.9 (11.5°), respectively. The distal transverse arch angle tended to decline with age (active: r = -0.18, p = 0.07, 95% confidence interval = -0.36 to 0.02; passive: r = -0.40, p ≤ 0.001, 95% confidence interval = -0.55 to -0.23). The u-ROM% of the hand arch in grasping and pinching ranged from 65.5 (9.8)% to 84.6 (11.6)% and from 52.1 (7.9)% to 67.4 (9.1)%, respectively, against active and passive motions. The ring finger component was significantly higher than the fifth finger component (active: p = 0.08 to <0.001, effect size = -0.17 to -0.69; passive: p ≤ 0.001, effect size= -0.71 to -0.86). A similar trend was observed in both men and women.

CONCLUSIONS

Therapists should evaluate the movement of the distal transverse arch of the injured hand in detail and consider the age, sex, and component of the hand arch when intervening.

Normative values for hand grip and pinch strength for 6 to 18 year-olds in Saudi Arabia

BACKGROUND

Normative values for hand grip and pinch strength among children in Saudi Arabia has not been well established. Therefore, the main aim of this study is to establish normative values for hand grip and pinch strength in children aged 6 to 18 years in Saudi Arabia.

METHODS

A cross-sectional study was conducted from different 5 regions in Saudi Arabia. Participants between the age of 6 years and 18 years old were recruited through different primary and secondary schools in Saudi Arabia. Data for age, gender, Body Mass Index, and preferred hand were collected. Hand grip strength was measured using digital hand dynamometer and the tip pinch, palmar pinch, and key pinch strength were measured using the hydraulic pinch gauge.

RESULTS

A total of 616 participants included in this study (318 boys and 298 girls). Participants were stratified into 5 chronological age groups of 6-7 years, 8-9, 10-11, 12-13, 14-15, 16-17, and 18 years. The results showed an overall trend of increasing hand grip strength and pinch strength with age regardless of hand preference. Boys had significantly higher grip strength than girls in all age groups (P < 0.05).

CONCLUSION

This study established normative values for hand grip and pinch strength in the healthy Saudi pediatric and adolescent population, using boys and girls aged 6 to 18. The outcomes of this study also demonstrated that gender, age, and hand preference can all have an impact on how strong a handgrip develops.

The effect of pinch span on pinch force sense in healthy participants

The purpose of the current investigation was to evaluate the effect of pinch span on the perception of pinch force in typical participants. The healthy participants (10 males and 10 females) conducted an ipsilateral force reproduction test with three distinct pinch spans (2, 4, and 6 cm) at three distinct forces of 10%, 30%, and 50% maximum voluntary isometric contraction. The findings revealed a significantly greater consistency (lower variable error (VE)) of 4 cm compared with 2 and 6 cm pinch spans. Our study also showed that the participants might use a larger force (more overestimated) output for larger pinch spans (4 and 6 cm) than small pinch spans (2 cm). These results may offer significant insights into the higher rates of musculoskeletal disorders among females, enabling researchers and clinicians to design novel interventions and tools to improve pinch force perception and reduce hand injury rates in males and females.

Brief research report: Effects of Pinch deficiency on cartilage homeostasis in adult mice

Pinch1 and Pinch2 are LIM domain-containing proteins with crucial functions in mediating focal adhesion formation. Our previous studies have demonstrated that Pinch1/2 expression is essential for cartilage and bone formation during skeletal development in mice. Loss of Pinch expression (Prx1^Cre; Pinch1^flox/flox; Pinch2^-/-) inhibits chondrocyte proliferation and promotes chondrocyte apoptosis, resulting in severe chondrodysplasia and limb shortening. Based on these observations, we wonder if Pinch proteins have a role in adult cartilage and whether Pinch deficiency will compromise cartilage homeostasis and promote osteoarthritis (OA)-related defects in adult mice. To this end, we generated the Aggrecan^CreERT2; Pinch1^flox/flox; Pinch2^-/- mice, in which the Pinch1 gene can be inducibly deleted in aggrecan-expressing chondrocytes by tamoxifen and the Pinch2 gene is globally inactivated. Immunofluorescent staining confirmed that the expression of Pinch proteins was significantly decreased in articular cartilage in tamoxifen-treated adult Aggrecan^CreERT2; Pinch1^flox/flox; Pinch2^-/- mice. Unexpectedly, our results showed that Pinch loss did not induce marked abnormalities in articular cartilage and other joint tissues in the knee joints of either adult (10-month-old) mice or aged (17-month-old) mice. In a destabilization of the medial meniscus (DMM)-induced OA model, the surgically-induced OA lesions were comparable between Pinch-deficient mice and control mice. Given the fact that Pinch proteins are essential for chondrogenesis and cartilage formation during skeletal development, these findings suggest that Pinch expression is seemingly not indispensable for adult cartilage homeostasis in mice.

Evaluation of functional recovery in the intrinsic and flexor muscles after nerve transfer for ulnar nerve lesion. A new measurement method: The Cha method

"Supercharge" end-to-side (SETS) nerve transfer for lesions of the proximal ulnar nerve is a recognized novel option, but improvement in motor function after surgery has not been properly evaluated. We therefore propose a modified method for quantitative evaluation of improvement in the intrinsic hand strength. We screened 216 patients with proximal ulnar nerve lesions who presented to our outpatient department from 2012 to 2020. Of these, 101 met our inclusion/exclusion criteria and were evaluated just before surgery. We used a novel method to measure finger abduction ("2nd-abd"), adduction ("5th-add"), and ring and little finger flexion strength ("4,5 grip"), and analyzed correlations with established pinch strength data. The male:female sex ratio was 86:15, and the ratio dominant to nondominant arm involvement was 68:33. All strength measurements were analyzed as percentage affected to contralateral normal side. On Pearson correlation analysis, the strength ratios for "4,5 grip", "2nd-abd", and "5th-add", but not "5 fingers (total) grip", showed significant positive correlation with key and oppositional pinch strength (all p &lt; 0.001). Additionally, linear regression analysis showed identical results for each strength correlation with key/oppositional pinch, except for "5 fingers total) grip" (all, p &lt; 0.001). SETS is a reasonable alternative for lesions of the proximal ulnar nerve. The measurement method we propose is feasible for specific assessment of intrinsic muscle strength, which improves after surgery. LEVEL OF EVIDENCE: Diagnostic, level IV.

A Pinch Test to Correct an Unfolded Helix: An Innovative and Predictable Technique

The unfolded helix is an ear deformity more frequent than expected. It might be presented alone or combined with other scapha or concha anomalies, giving the appearance of big and prominent ears. Currently, there are few reports published about its restoration and few modifications have been made to its original surgical approaches since the 1970s. The technique herein described aims to facilitate the helix rim restoration procedure by considering the following preoperative and surgical advices. The preoperative use of the pinch test allows to better understand the patients' expectations, helps to explain the future outcomes to them and simplifies the marking of the tissue to be removed. The additional bilateral only-cartilage resections and the maintenance of the skin excess permit to optimize the cosmetic outcomes. This innovative surgical approach for the helix rim restoration is reliable, has little morbidity associated and presents consistent effective results. LEVEL OF EVIDENCE V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Effects of wearing of metacarpal gloves on hand dexterity, function, and perceived comfort: A pilot study

Metacarpal gloves are commonly used in heavy-duty industries such as mining and are typically thicker and bulkier than manufacturing or assembly industrial gloves. This pilot study investigates the impact of wearing metacarpal gloves on hand dexterity, functional capabilities, and perceived comfort. Four types of commercially available metacarpal gloves were selected for evaluation in a randomized controlled trial. Evaluations included turning and placing tests, also grip, pinch, and screwdriver tests, and rating of the perceived level of effort. Dexterity test results showed that metacarpal gloves significantly reduced the ability to perform motor tasks requiring coordination compared to bare hands. Hand functions such as gripping, pinching, and forearm rotations were not significantly affected. However, the perceived level of effort needed to complete those hand functions increased as the metacarpal glove's bulkiness increased. High levels of mechanical protection typically offered by metacarpal gloves can inversely affect hand dexterity and hand exertion.

Analysis of hand-forearm anthropometric components in assessing handgrip and pinch strengths of school-aged children and adolescents: a partial least squares (PLS) approach

Background

The purpose of this study was to examine the influence of hand-forearm anthropometric dimensions on handgrip and pinch strengths among 7–18 years children and adolescents and to investigate the extent to which these variables can be used to predict hand strength.

Methods

Four types of hand strengths including handgrip, tip to tip, key, and three-jaw chuck pinches were measured in 2637 healthy children and adolescents (1391 boys and 1246 girls) aged 7–18 years using standard adjustable Jamar hydraulic hand dynamometer and pinch gauge. A set of 17 hand-forearm anthropometric dimensions were also measured with an accurate digital caliper and tape measure.

Results

No significant differences were found between the hand strengths of boys and girls up to the age of 10 years. Gender related differences in handgrip and pinches were observed from the age of 11 years onwards, with boys always being stronger. The dominant hand was stronger than the non-dominant hand (8% for handgrip and by about 10% for all three types of pinches). The strongest correlations were found between the hand length and hand strengths (r > 0.83 for handgrip and three all pinches; p < 0.001, 2-tailed). Based on the partial least squares (PLS) analysis, 8 out of 17 anthropometric indices including hand length, hand circumference, thumb length, index finger length, middle finger length, and forearm length had considerable loadings in the PLS analysis, which together accounted for 46% of the total variance.

Conclusions

These results may be used by health professionals in clinical settings as well as by designers to create ergonomic hand tools.

A novel nerve transfer: The first palmar interosseous motor branch of the ulnar nerve to the recurrent motor branch of the median nerve

INTRODUCTION

The recovery of recurrent motor branch of the median nerve might be delayed in high level median nerve injuries due to the long reinnervation distance. The aim of this study is to define a novel nerve transfer to restore the opposition and pinch.

METHODS

Two fresh frozen hand cadavers were used for the study. The motor branch of the first palmar interosseous muscle of the ulnar nerve was identified and dissected. Thenar branch of the median nerve was dissected from its insertion site. The motor branch of the first palmar interosseous muscle of the ulnar nerve was transferred to the thenar motor branch of the median nerve. Axon counts were examined histopathologically. Clinically this nerve transfer was performed for two female patients with a high-level median nerve injury. Mehta opposition scores were 21 and 20, respectively and the results were satisfactory six months after the surgery.

DISCUSSION

Although exploration and repair are recommended as the first treatment for median nerve injuries, the waiting time until the motor branch is reinnervated is critical in high level lesions. Nerve transfers become very important for fast recovery.

CONCLUSIONS

This new nerve transfer proposal may be an important step in nerve transfer surgery.

The comparison of pinch strength among female typists and female non-typists

BACKGROUND

Typing is a common activity involving repetitive motion that can increase the risk of work-related injuries. To the best of our knowledge, the effect of typing on the pinch strength has not been investigated so far.

OBJECTIVE

To investigate the pinch strength amongst female typists and non-typists.

METHOD

Thirty female typists and 30 female non-typists, aged 20-30 years old, participated in this prospective study. The pinch strength of the second, third, fourth and fifth fingers of the dominant hand was measured in a sitting position, using a pinch gauge. The data were analyzed using independent sample t-test.

RESULTS

The results showed that there were significant differences in the pinch strength of the second, third and fourth fingers between the two groups. The strength of these fingers was reduced more than that in female non-typists.

CONCLUSION

Our results suggest that pinch strength might have decreased in female typists due to sharing common attentional resources, muscle fiber composition, and muscle fiber fatigue.

Characterization of corticospinal activation of finger motor neurons during precision and power grip in humans

Direct and indirect corticospinal pathways to finger muscles may play a different role in control of the upper extremity. We used transcranial magnetic stimulation (TMS) and coherence analysis to characterize the corticospinal drive to the first dorsal interosseous (FDI) and abductor pollicis brevis (APB) when active during a precision and power grip task. In experiment 1, single motor units were recorded during precision grip and power grip in 20 adults (25.2 ± 7.1 years). Post-stimulus time histograms (PSTH) were obtained following TMS. In experiment 2, coherence and cross-correlation analysis of the FDI and APB surface EMG were used to investigate the temporal organization of corticospinal drive during precision grip and power grip in 15 adults (27.4 ± 8.1 years). We found no significant differences in PSTH peak onset (26.6 ± 1.9 vs. 26.7 ± 2.0 ms, p = 0.75), maximal peak (27.4 ± 1.9 vs. 27.4 ± 1.9 ms, p = 1.0) or peak duration (2.3 ± 1.1 vs. 2.3 ± 1.0 ms, p = 0.75) for the 11 recovered motor units during precision grip and power grip. Also, no significant difference in coherence or the width of the synchronization peaks during precision grip (7.2 ± 3.7 ms) and power grip (7.9 ± 3.1 ms) could be observed (p = 0.59). The short duration of peaks elicited in the PSTH of single motor units following TMS and central synchronization peaks of voluntarily activated motor units during precision and power grip suggests that the direct corticospinal pathway (the corticomotoneuronal system) is equally involved in the control of both tasks. The data do not support that indirect pathways would make a larger contribution to power grip.

Index finger and thumb kinematics and performance measurements for common touchscreen gestures

This study aimed to quantify differences in 7 touchscreen gestures. Eighteen participants performed index finger tapping, sliding in 4 orthogonal directions, and index finger and thumb pinch and stretch gestures on a touchscreen tablet computer. We hypothesized that two finger gestures would require longer task completion time and greater finger joint excursions than sliding gestures using only the index finger. We measured task completion times and finger joint kinematics. Tapping showed the fastest average (±SD) task completion time, 567(190) ms, of all gestures (p < 0.001). Pinch had faster task completion time, 765(277) ms, than all single-finger sliding gestures (p < 0.001). Stretch was faster to complete at 843(317) ms (p < 0.001) than all sliding gestures except slide right. Stretch demonstrated greater mean index finger metacarpophalangeal flexion/extension joint excursions, 63(16)°, compared to sliding gestures, 34(10)°, and tapping, 27(13)° (p < 0.01). Overall, two-finger gestures were faster to complete and showed greater joint excursions than single-finger sliding gestures.

Low Median Nerve Transfers (Opponensplasty)

Opposition is the placement of the thumb opposite the fingers into a position from which it can work. This motion requires thumb palmar abduction, flexion, and pronation, which are provided by the abductor pollicis brevis, flexor pollicis brevis (FPB), and opponens pollicis. In the setting of a median nerve palsy, this function is typically lost, although anatomic variations and the dual innervation of the FPB may prevent complete loss at times. There are multiple well described and accepted tendon transfers to restore opposition, none of which have been proven to be superior to the others.

Digit mechanics in relation to endpoint compliance during precision pinch

This study investigates the mechanics of the thumb and index finger in relation to compliant endpoint forces during precision pinch. The objective was to gain insight into how individuals modulate motor output at the digit endpoints and joints according to compliance-related sensory feedback across the digits. Thirteen able-bodied subjects performed precision pinch upon elastic resistance bands of a customized apparatus instrumented with six degree-of-freedom load-cells. Compliance levels were discretely adjusted according to the number of bands connected. Subjects were provided visual feedback to control the rate of force application. Fifteen repetitions of low-to-moderate force (<20N) pinches were analyzed at each of five compliance levels, during which force and motion data were collected. Joint angles and moments normalized by pinch force magnitude were computed. Second-order polynomials were used to characterize joint mechanics as a function of compliance. The joint degrees-of-freedom (DOFs) at the finger showed greater dependence on compliance for angular position while the thumb joint DOFs demonstrated greater dependence for normalized joint moment. The digits also adjusted coordination of their endpoint forces according to compliance. Overall, the finger may be altering its position to increase load to the joints of the thumb with changing compliance. These findings describe naturally emergent changes in digit mechanics for compliant precision pinch, which involves motor execution in response to endpoint sensory feedback. Identifying and understanding these motor patterns may provide theoretical basis for restoring and rehabilitating sensorimotor pathologies of the hand.

Online kinematic regulation by visual feedback for grasp versus transport during reach-to-pinch

PURPOSE

This study investigated novel kinematic performance parameters to understand regulation by visual feedback (VF) of the reaching hand on the grasp and transport components during the reach-to-pinch maneuver. Conventional metrics often signify discrete movement features to postulate sensory-based control effects (e.g., time for maximum velocity to signify feedback delay). The presented metrics of this study were devised to characterize relative vision-based control of the sub-movements across the entire maneuver.

METHODS

Movement performance was assessed according to reduced variability and increased efficiency of kinematic trajectories. Variability was calculated as the standard deviation about the observed mean trajectory for a given subject and VF condition across kinematic derivatives for sub-movements of inter-pad grasp (distance between thumb and index finger-pads; relative orientation of finger-pads) and transport (distance traversed by wrist). A Markov analysis then examined the probabilistic effect of VF on which movement component exhibited higher variability over phases of the complete maneuver. Jerk-based metrics of smoothness (minimal jerk) and energy (integrated jerk-squared) were applied to indicate total movement efficiency with VF.

RESULTS/DISCUSSION

The reductions in grasp variability metrics with VF were significantly greater (p<.05) compared to transport for velocity, acceleration, and jerk, suggesting separate control pathways for each component. The Markov analysis indicated that VF preferentially regulates grasp over transport when continuous control is modeled probabilistically during the movement. Efficiency measures demonstrated VF to be more integral for early motor planning of grasp than transport in producing greater increases in smoothness and trajectory adjustments (i.e., jerk-energy) early compared to late in the movement cycle.

CONCLUSIONS

These findings demonstrate the greater regulation by VF on kinematic performance of grasp compared to transport and how particular features of this relativistic control occur continually over the maneuver. Utilizing the advanced performance metrics presented in this study facilitated characterization of VF effects continuously across the entire movement in corroborating the notion of separate control pathways for each component.

Carpal tunnel syndrome with thenar atrophy: evaluation of the pinch and grip strength in patients undergoing surgical treatment

This aim of this study was to evaluate the progression of grip, tip pinch, key (lateral) pinch, and tripod pinch strengths in patients suffering from carpal tunnel syndrome with thenar atrophy following surgery. Between October 2008 and May 2010, 46 patients (49 hands) with carpal tunnel syndrome associated with thenar atrophy underwent surgery. Thenar atrophy was assessed by clinical inspection. Evaluations for grip strength and for tip, key, and tripod pinch strengths were made using a hydraulic hand dynamometer grip and a hydraulic pinch gauge, respectively. These measurements were taken before surgery and at 3 and 6 months after the procedure. When we compared the averages of all forces measured in the affected hand before the surgery with all forces measured at 3 months postoperative, we found no significant differences. However, after 6 months, we found significant differences for all four strength tests as compared with those measurements taken preoperatively and at the 3 month time point. Our results suggest that patients with thenar atrophy show increased grip strength and pinch strength by the sixth month after surgical treatment.