Maximum Pinch Strength Research Articles

Metacarpophalangeal joint angle of the thumb during maximal pinch strength: a study of healthy volunteers.

Mean metacarpophalangeal joint angles of the thumb during maximal pinch were 9° greater in men than in women. More flexion was not associated with more force during key pinch, but a moderate association was found for palmar pinch, especially in men.

Fine adaptive precision grip control without maximum pinch strength changes after upper limb neurodynamic mobilization

Before and immediately after passive upper limb neurodynamic mobilizations targeting the median nerve, grip (G_F) and load (L_F) forces applied by the thumb, index and major fingers (three-jaw chuck pinch) were collected using a manipulandum during three different grip precision tasks: grip-lift-hold-replace (GLHR), vertical oscillations (OSC), and vertical oscillations with up and down collisions (OSC/COLL/u, OSC/COLL/d). Several parameters were collected or computed from G_F and L_F. Maximum pinch strength and fingertips pressure sensation threshold were also examined. After the mobilizations, L_F max changes from 3.2 ± 0.4 to 3.4 ± 0.4 N (p = 0.014), dG_F from 89.0 ± 66.6 to 102.2 ± 59.6 N~text{s}^{-1} (p = 0.009), and dL_F from 43.6 ± 17.0 to 56.0 ± 17.9 N~text{s}^{-1} (p<0.001) during GLHR. L_F SD changes from 0.9 ± 0.3 to 1.0 ± 0.2 N (p = 0.004) during OSC. L_F peak changes from 17.4 ± 8.3 to 15.1 ± 7.5 N (p<0.001), G_F from 12.4 ± 6.7 to 11.3 ± 6.8 N (p = 0.033), and L_F from 2.9 ± 0.4 to 3.00 ± 0.4 N (p = 0.018) during OSC/COLL/u. G_F peak changes from 13.5 ± 7.4 to 12.3 ± 7.7 N (p = 0.030) and L_F from 14.5 ± 6.0 to 13.6 ± 5.5 N (p = 0.018) during OSC/COLL/d. Sensation thresholds at index and thumb were reduced (p = 0.001, p = 0.008). Precision grip adaptations observed after the mobilizations could be partly explained by changes in cutaneous median-nerve pressure afferents from the thumb and index fingertips.

Neuropsychological and neurophysiological correlates of fatigue in post-acute patients with neurological manifestations of COVID-19: Insights into a challenging symptom

More than half of patients who recover from COVID-19 experience fatigue. We studied fatigue using neuropsychological and neurophysiological investigations in post-COVID-19 patients and healthy subjects. Neuropsychological assessment included: Fatigue Severity Scale (FSS), Fatigue Rating Scale, Beck Depression Inventory, Apathy Evaluation Scale, cognitive tests, and computerized tasks. Neurophysiological examination was assessed before (PRE) and 2 min after (POST) a 1-min fatiguing isometric pinching task and included: maximum compound muscle action potential (CMAP) amplitude in first dorsal interosseous muscle (FDI) following ulnar nerve stimulation, resting motor threshold, motor evoked potential (MEP) amplitude and silent period (SP) duration in right FDI following transcranial magnetic stimulation of the left motor cortex. Maximum pinch strength was measured. Perceived exertion was assessed with the Borg-Category-Ratio scale.Patients manifested fatigue, apathy, executive deficits, impaired cognitive control, and reduction in global cognition. Perceived exertion was higher in patients. CMAP and MEP were smaller in patients both PRE and POST. CMAP did not change in either group from PRE to POST, while MEP amplitudes declined in controls POST. SP duration did not differ between groups PRE, increased in controls but decreased in patients POST. Patients' change of SP duration from PRE to POST was negatively correlated to FSS.Abnormal SP shortening and lack of MEP depression concur with a reduction in post-exhaustion corticomotor inhibition, suggesting a possible GABAB-ergic dysfunction. This impairment might be related to the neuropsychological alterations.COVID-19-associated inflammation might lead to GABAergic impairment, possibly representing the basis of fatigue and explaining apathy and executive deficits.

Effects of a task-based biofeedback training program on improving sensorimotor function in neuropathic hands in diabetic patients: a randomized controlled trial.

Symptoms of diabetic hands have been gradually elucidated, however the interventions for these hand problems are typically underemphasized. Few studies have discussed intervention effects on sensorimotor problems in hands, which prevent diabetic patients from executing their daily routines and lower their quality of life (QoL). This study has investigated the effects of task-based biofeedback training compared with home-based programs on sensorimotor function and QoL in diabetic patients with neuropathic hands. A single blind randomized controlled trial. Outpatient clinic at a university hospital. Thirty-eight patients with diabetic hand neuropathy whose sensorimotor functions were impaired based on screening with a pinch-holding-up activity (PHUA) test. Participants were randomly assigned to either a computerized evaluation and re-education biofeedback (CERB) (N.=20) or a home-based (tendon gliding exercise in conjunction with resistive exercise) (N.=18) group. The primary outcome was sensorimotor control of a hand using the PHUA test. Secondary outcomes included changes in Semmes-Weinstein monofilament, two-point discrimination, the Purdue Pegboard test and a self-reported QoL questionnaire. The measurements were conducted before and after a 6-week treatment program. The CERB group significantly improved efficiency in pinch force output during the PHUA test by reducing the percentage of maximum pinch strength (change from 34.5±11.66 to 30.7±10.16%, P=0.001), and there was a statistically significant between-group difference (P=0.00, 95% CI: -12.59 to -3.34, F=9.42). The CERB group showed superior treatment effects as compared to the control group on the two-point discrimination results (P=0.01) as well as the pin insertion subtests in the Purdue pegboard test (P=0.01). The QoL results also revealed significant between-group differences in several items of the Diabetes-39 (P<0.05). This study showed that a task-based biofeedback training program provides superior benefits for restoration of hand sensorimotor functioning in diabetic patients as compared to a home-based program combining tendon gliding exercise and resistive exercise. Using task-based biofeedback training as one of the rehabilitation strategies may be an effective approach for restoration of sensory function, precision pinch performance, hand dexterity, and QoL for patients with diabetes-related neuropathy.

Conformity of modified O-ring test and maximal pinch strength for cross tape application direction.

Background:Although cross tape has recently been used by clinicians for various musculoskeletal conditions, scientific studies on the direction of cross tape application are lacking.Methods:The present study aimed to investigate whether the direction of cross tape application affected the outcomes of the modified O-ring test and maximal pinch strength using a pinch gauge and the conformity between these 2 tests when cross tape was applied to the forearm muscles of individuals with no upper extremity pain and no restriction of joint range of motion.This study used a single-blinding crossover design. The subjects comprised 39 adults (16 men and 23 women). Cross tape was applied to the dominant hand so that the 4 rows were at an angle of 45° to the right or left of the direction of the flexor digitorum superficialis muscle fibers, and then the subjects underwent a modified O-ring test and a test of maximal pinch strength using a pinch gauge. Both tests were performed in both directions, and the order of the directions and tests was randomized. SPSS 18.0 was used for statistical analysis. Cohen's kappa coefficient was used to analyze the conformity of the results from the 2 tests. The statistical significance level was P < .05.Results:A positive response in the modified O-ring test and maximal pinch strength were both affected by cross tape direction. The modified O-ring test and maximal pinch strength using pinch gauge results were in agreement (P < .00), and the kappa coefficient was significant at 1.00.Conclusion:The direction of cross tape application that produced a positive response in the modified O-ring test also produced greater maximal pinch strength. Thus, we propose that when applying cross tape to muscles, the direction of the 4 lines of the cross tape should be 45° relative to the direction of the muscle fibers, toward the side that produces a positive response in the modified O-ring test or produces the greatest maximal pinch strength using a pinch gauge.

Squeeze Me if You Can: Variability in Force Requirements to Extract a Drop From Common Glaucoma Bottles

To determine the force requirements to dispense a single drop from commonly prescribed brand and generic topical glaucoma medications and correlate these findings with pinch strength in a representative patient population. Four bottles of each medication were tested: 2 in the vertical and 2 in the horizontal orientation. Bottles were housed in a customized force gauge apparatus designed to mimic ballpoint fingertip contact with a bottle tip. For all bottles, each of the first 10 dispensed drops was tested and then tests were performed in increments of 10 until the bottle was empty. For each tested drop, the maximum force and displacement were electronically measured. Concurrently, maximum pinch strength was measured on consecutive glaucoma patients. A total of 84 bottles from 21 bottle designs were tested. There was significant variability across the designs, with roughly a 7-fold (0.67 to 4.49 kgf) and 4-fold (0.81 to 3.00 kgf) difference in force requirements in the vertical and horizontal positions, respectively. Of 53 enrolled patients in the glaucoma clinic, the mean pinch strength was 5.05 (range, 1.23 to 10.4 kgf) and 4.82 (range, 1.47 to 10.67 kgf) kgf for the right and left hands, respectively. There is statistically significant variability in the force required to squeeze a drop from common glaucoma medications, and a representative sampling of clinic patients suggests that many likely struggle with the force requirements of several bottle designs. These data further support standardization of topical glaucoma drug delivery and design.

Early Active Rehabilitation After Grip Reconstructive Surgery in Tetraplegia

ObjectiveTo describe and evaluate the concept of early active rehabilitation after tendon transfer to restore grip function in tetraplegia. DesignRetrospective cohort study. SettingTwo nonprofit rehabilitation units in Sweden and Switzerland. ParticipantsAll patients with tetraplegia who underwent tendon transfer to restore grip ability during 2009 to 2013 (N=49). InterventionReconstructive tendon transfer surgery with early active rehabilitation to restore grip ability in tetraplegia. Main Outcome MeasuresGrip and pinch strength, grip ability test, and outcome of prioritized activities. ResultsIn the 49 surgeries performed, postoperative complications included 2 patients with bleeding and 2 infections related to the surgery. There were no reported ruptures or lengthening of transferred tendons. Within 24 hours after surgery, all 47 patients (100%) with finger flexion reconstruction succeeded to activate their finger flexion. All but 1 patient with reconstructed thumb flexion sucessfully activated their thumb flexion (n=40). Three weeks after surgery, all patients (100%) were able to perform basic activities of daily living, and instrumental activities of daily living were achieved by 74%. One year after surgery, the maximum grip strength in restored finger flexion was on average 6.9kg (range, 1.5–15kg; n=29). The maximum pinch strength in restored thumb flexion was on average 3.7kg (range, 1–20; n=29). On average, grip ability improved from 33 to 101 (n=19) according to the COPM. Prioritized activity limitations, as measured with the COPM, equated to an average of 3.5 steps (2.5 steps preoperatively to 6 steps postoperatively). Patients' perceived satisfaction with this improvement was 4 steps (increasing from 2 steps preoperatively to 6 steps postoperatively). ConclusionsGrip reconstructive surgery followed by early active rehabilitation can be considered a reliable procedure that leads to substantial improvements in grip and pinch strength and activity performance among patients with tetraplegia.

Impacts of elevated glycaemic haemoglobin and disease duration on the sensorimotor control of hands in diabetes patients.

To understand the impacts of disease chronicity and hyperglycaemia on sensorimotor control of hands of diabetic patients, this study investigated the differences in hand sensation, strength and motor control by applying the pinch-holding-up activity test for patients with diabetes mellitus (DM) with different levels of glycaemic control and disease chronicity. One hundred and fifty-nine patients with clinically defined DM were included. Semmes-Weinstein monofilament, static two-point discrimination and moving two-point discrimination, maximal pinch strength precision pinch performance tests and nerve conduction studies (NCS) of the subjects were carried out. Forty-seven (29.6%) patients were in the HbA(1c) < 7% category, and 112 (70.4%) patients were in the >7% group. There were 87 (54.7%) patients with the disease duration <10 years, and 72 (45.3%) patients with disease duration ≧10 years. The severity of hyperglycaemia significantly impacts the results for Semmes-Weinstein monofilament, precision pinch force control, sensory and motor NCS tests (p < 0.05). In addition, the chronicity of disease influences the motor control of precision pinch performance and the amplitude of motor NCS (p < 0.05) for the diabetes patients. The evidence suggests that disease chronicity and hyperglycaemia have impacts on sensorimotor control in the hands of DM patients. In addition, the efficiency of prehensile forces of hand-to-object interactions in the pinch-holding-up activity test could be significant for identifying hand function, as well as pathologic changes in median nerve function, for patients with DM.

Maximum voluntary isometric pinch contraction and force-matching from the fourth to the eighth decades of life

Understanding the effects of age and gender on pinch strength, variability, and accuracy and how one's hand function changes with age better enables those in the preventative and rehabilitative fields to combat these losses. The present study examined fine motor maximum pinch strength [maximum voluntary isometric contraction (MVIC)] as well as the ability to maintain 5% MVIC accurately and consistently in five decades. One hundred adults in five groups, 20 in each decade of life from 30 to 79 years old, were nonrandomly recruited from the community. A two-way analysis of variance applied to MVIC, and a two-way multivariate analysis of variance applied to the variability (coefficient of variability) and accuracy (root mean square error), plus correlation and regression analyses, were used to determine decade and gender effects on pinch force. The task involved using isometric pinch control of a computer cursor to match a 5% of MVIC force level represented by a horizontal line. MVIC and force-matching steadiness and accuracy across all ages were not significantly different until the eighth decade (P<0.01). Men were stronger (P<0.001) but performed low-level force-matching with greater error (P<0.001) than women. Strength was not correlated with steadiness but was weakly correlated with accuracy (r=0.293, P<0.01), and steadiness and accuracy were strongly correlated (r=0.783, P<0.001). Decade and gender were moderate and strong predictors of accuracy and steadiness, respectively. In conclusion, age and gender differences were evident in pinch-force strength and control.

Carpal tunnel syndrome impairs thumb opposition and circumduction motion.

Carpal tunnel syndrome is associated with sensory and motor impairments resulting from the compressed and malfunctioning median nerve. The thumb is critical to hand function, yet the pathokinematics of the thumb associated with carpal tunnel syndrome are not well understood. The purpose of this study was to evaluate thumb motion abnormalities associated with carpal tunnel syndrome. We hypothesized that the ranges of translational and angular motion of the thumb would be reduced as a result of carpal tunnel syndrome. Eleven patients with carpal tunnel syndrome and 11 healthy control subjects voluntarily participated in this study. Translational and angular kinematics of the thumb were obtained using marker-based video motion analysis during thumb opposition and circumduction movements. Motion deficits were observed for patients with carpal tunnel syndrome even though maximum pinch strength was similar. The path length, normalized by palm width of the thumb tip for the patients with carpal tunnel syndrome was less than for control participants (opposition: 2.2 palm width [95% CI, 1.8-2.6 palm width] versus 3.1 palm width [95% CI, 2.8-3.4 palm width], p < 0.001; circumduction: 2.2 palm width [95% CI, 1.9-2.5 palm width] versus 2.9 palm width [95% CI, 2.7-3.2 palm width], p < 0.001). Specifically, patients with carpal tunnel syndrome had a deficit of 0.3 palm width (95% CI, 0.04-0.52 palm width; p = 0.022) in the maximum position of their thumb tip ulnarly across the palm during opposition relative to control participants. The angular ROM also was reduced for the patients with carpal tunnel syndrome compared with the control participants in extension/flexion for the metacarpophalangeal (opposition: 34° versus 58°, p = .004; circumduction: 33° versus 58°, p < 0.001) and interphalangeal (opposition: 37° versus 62°, p = .028; circumduction: 41° versus 63°, p = .025) joints. Carpal tunnel syndrome disrupts kinematics of the thumb during opposition and circumduction despite normal pinch strength. Improving understanding of thumb pathokinematics associated with carpal tunnel syndrome may help clarify hand function impairment associated with the syndrome given the critical role of the thumb in dexterous manipulation.

How the impact of median neuropathy on sensorimotor control capability of hands for diabetes: an achievable assessment from functional perspectives.

To comprehend the sensorimotor control ability in diabetic hands, this study investigated the sensation, motor function and precision pinch performances derived from a pinch-holding-up activity (PHUA) test of the hands of diabetic patients and healthy subjects. The precision, sensitivity and specificity of the PHUA test in the measurements of diabetic patients were also analyzed. We hypothesized that the diabetic hands would have impacts on the sensorimotor functions of the hand performances under functionally quantitative measurements. One hundred and fifty-nine patients with clinically defined diabetes mellitus (DM) and 95 age- and gender-matched healthy controls were included. Semmes-Weinstein monofilament (SWM), static and moving two-point discrimination (S2PD and M2PD), maximal pinch strength and precision pinch performance tests were conducted to evaluate the sensation, motor and sensorimotor status of the recruited hands. The results showed that there were significant differences (all p<0.05) in SWM, S2PD, M2PD and maximum pinch strength between the DM and control groups. A higher force ratio in the DM patients than in the controls (p<0.001) revealed a poor ability of pinch force adjustment in the DM patients. The percentage of maximal pinch strength was also significantly different (p<0.001) between the DM and control groups. The sensitivity, specificity and area under the receiver operating characteristic curve were 0.85, 0.51, and 0.724, respectively, for the PHUA test. Statistically significant degradations in sensory and motor functions and sensorimotor control ability were observed in the hands of the diabetic patients. The PHUA test could be feasibly used as a clinical tool to determine the sensorimotor function of the hands of diabetic patients from a functional perspective.

Reliability of pinch strength testing in elderly subjects with unilateral thumb carpometacarpal osteoarthritis.

[Purpose] The aim of this study was to examine the test-retest reliability of pinch strength testing in elderly subjects with thumb CMC OA. [Subjects and Methods] A total of 27 patients with unilateral right-thumb CMC OA (mean ± SD age: 81.3 ± 4.7 years) were recruited. Each patient performed three pain-free maximal isometric contractions on each hand on two occasions, one week apart. Three different measurements were taken: tip, tripod, and key pinch strength. Intraclass correlation coefficient (ICC), standard error of measurement (SEM), and 95% limits of agreement (LOA) calculations were performed. [Results] Test-retest reliability of measurements of tip, tripod, and key pinch strength was excellent for the affected side (ICC=0.93, 0.96, and 0.99) and the contralateral thumb (ICC=0.91, 0.92, and 0.94). [Conclusions] The present results indicate that maximum pinch strength can be measured reliably using the Pinch Gauge Dynamometer, in patients with thumb CMC OA, which enables its use in research and in the clinic to determine the effect of interventions on improving pinch strength.

Precision Pinch Performance in Patients With Sensory Deficits of the Median Nerve at the Carpal Tunnel

To investigate how sensory symptoms impact the motor control of hands, in this study we examined the differences in conventional sensibility assessments and pinch force control in the pinch-holding-up activity (PHUA) test between carpal tunnel syndrome (CTS) patients and healthy controls. CTS patients (n = 82) with 122 affected hands and an equal number of control subjects were recruited to participate in the threshold, discrimination, and PHUA tests. The patients showed significantly poorer hand sensibility and lower efficiency of force adjustment in the PHUA test as compared with the control subjects. Baseline pinch strength and the percentage of maximal pinch strength for the PHUA were significantly higher for the subgroup of sensory nerve action potential (SNAP) of <16 μV than for the subgroup of SNAP of 16 μV. Using a PHUA perspective to analyze the efficiency of force-adjustment could assist the clinical detection of sensory nerve dysfunction.

Interference Screw Fixation Versus Pulvertaft Weave in a Simulated Early-Motion Suspensionplasty Protocol

To compare interference screw fixation to Pulvertaft weave fixation in a cadaveric basal joint abductor pollicis longus (APL) suspensionplasty model with an early range of motion protocol. We asked whether the interference screw fixation would provide comparable initial stability while minimizing the dorsal incision and eliminating the prominent dorsal mass associated with the traditional Pulvertaft weave. Six matched cadaveric forearms underwent suspensionplasty with tendon fixation via an interference screw or a Pulvertaft weave. We then loaded the specimens to 10,000 cycles and used a modification of a previously validated cyclic pinch model. One third of the load required for maximal pinch strength was used. The APL was not loaded because we used the tendon for ligament reconstruction. We obtained measurements of residual trapezial space with feeler gauges after trapeziectomy, after suspensionplasty, and at 1,000-cycle intervals. Suspensionplasty with interference screw fixation maintained statistically significantly larger trapezial space heights compared with the Pulvertaft weave. Moreover, after the first 1,000 cycles, none of the specimens fixed with the interference screw lost further height up to the 10,000th cycle. All of the specimens fixed with the Pulvertaft weave continued to lose height with cycling, and 1 specimen showed contact of the first metacarpal with the scaphoid after only 1,000 cycles. With interference screw fixation, the height achieved initially and maintained through 10,000 cycles was an average of 5.5 mm. When the Pulvertaft weave was used, the height achieved was 3.0 mm initially, declining to 2.3 mm after 10,000 cycles. The polylactic acid interference screw was placed through a 5-mm dorsal stab incision and the extra tendon graft was cut flush as it exited the bone tunnel, eliminating the dorsal prominence associated with the Pulvertaft weave. Although traditional APL suspensionplasty with a Pulvertaft weave provides good initial stability, it requires a large dorsal incision and leaves a prominent dorsal mass that may be bothersome to some patients.

Correlation of digital sensibility and precision of pinch force modulation in patients with nerve repair

The outcome measures for patients following peripheral nerve repairs commonly include muscle strength and sensory assessments. However, no significant discussion exists on the impact of nerve injury on sensorimotor control. The objective of this longitudinal study was to explore the effects of nerve regeneration on the control of pinch force in executing functional tasks. Seven patients with digital or median nerve repairs were assessed by a custom-designed pinch device and conventional sensory tools at monthly intervals following nerve repair. These tools measured sensibility, maximum pinch strength, and anticipated pinch force adjustments to movement-induced load fluctuations in a pinch-holding-up activity (PHUA). Six force-related and temporal parameters for sensory measurement were used to determine improvements in pinch performance over time following sensory recovery. The results revealed significant differences in the parameters of peak pinch force, baseline pinch force, force ratio, and the percentage of maximal pinch force output at different points in the course of nerve regeneration. A strong relationship was also found between kinetic data from the PHUA test and the traditional sensibility tests for the nerve repair patients in the present study.

Functional sensibility assessment. part II: Effects of sensory improvement on precise pinch force modulation after transverse carpal tunnel release

Patients with median nerve compression at the carpal tunnel often have poor sensory afferents. Without adequate sensory modulation control, these patients frequently exhibit clumsy performance and excessive force output in the affected hand. We analyzed precision grip function after the sensory recovery of patients with carpal tunnel syndrome (CTS) who underwent carpal tunnel release (CTR). Thirteen CTS patients were evaluated using a custom-designed pinch device and conventional sensory tools before and after CTR to measure sensibility, maximum pinch strength, and anticipated pinch force adjustments to movement-induced load fluctuations in a pinch-holding-up activity. Based on these tests, five force-related parameters and sensory measurements were used to determine improvements in pinch performance after sensory recovery. The force ratio between the exerted pinch force and maximum load force of the lifting object was used to determine pinch force coordination and to prove that CTR enabled precision motor output. The magnitude of peak pinch force indicated an economic force output during manipulations following CTR. The peak pinch force, force ratio, and percentage of maximum pinch force also demonstrated a moderate correlation with the Semmes-Weinstein test. Analysis of these tests revealed that improved sensory function helped restore patients' performance in precise pinch force control evaluations. These results suggest that sensory information plays an important role in adjusting balanced force output in dexterous manipulation.

Measuring pad–pad pinch strength in a non-human primate: Macaca fascicularis

The primary purpose of this study was to establish a methodology for determining and perhaps predicting (via regression analysis of anthropometric measures) Macaca fascicularis isometric pinch strength for a specific task. The larger purpose of this work was to properly scale a pinching task for the monkeys in order to study dose-response relationships in a non-human primate model for carpal tunnel syndrome. Three female and one male macaque ( n = 4) of varying size and age were trained to perform a left-handed pad–pad pinch. The task required 60° of wrist flexion at a static pinching distance of 3 cm between the thumb and fingers. Subjects were trained for a period of 20-weeks. After that time, an analysis of performance gradients found that they had each reached a plateau in their force output. Pinch strength for the four animals ranged from 29.4 to 59.8 N. Regression analysis revealed that body mass (kg) and wrist circumference (cm) were both predictive of pinch strength, exhibiting adjusted R 2 values of 0.93 ( p = 0.024) and 0.96 ( p = 0.015), respectively. Thus, the results suggest that maximal pinch strength could be acceptably estimated in future subjects using either the wrist circumference or the body mass measures, as both were strong predictors of pad–pad pinch strength.