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Introduction: In the assessment of hand and upper limb function, grip strength is of the major importance. The measurement by dynamometers has been established., Purpose of the Study: In this study, the effect of a simulated ulnar nerve lesion on different grip force measurements was evaluated., Methods: In 25 healthy volunteers, grip force measurement was done by the JAMAR dynamometer (Fabrication Enterprises Inc, Irvington, NY) for power grip and by a pinch strength dynamometer for tip pinch strength, tripod grip, and key pinch strength., 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 ulnar nerve block were used to examine within-subject change., Results: In power grip, there was a significant reduction of maximum grip force of 26.9% with ulnar nerve block compared with grip force without block (P < .0001). Larger reductions in pinch strength were observed with block: 57.5% in tip pinch strength (P < .0001), 61.0% in tripod grip (P < .0001), and 58.3% in key pinch strength (P < .0001)., Discussion: The effect of the distal ulnar nerve block on grip and pinch force could be confirmed. However, the assessment of other dimensions of hand strength as tip pinch, tripod pinch and key pinch had more relevance in demonstrating hand strength changes resulting from an distal ulnar nerve lesion., Conclusions: The measurement of tip pinch, tripod grip and key pinch can improve the follow-up in hand rehabilitation., Level of Evidence: II., (Copyright © 2017 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.)

Background: Peripheral lesions of the median nerve cause characteristic changes of the grip function of the hand. For evaluating grip force changes, measurement by dynamometers (JAMAR dynamometer and pinch dynamometer) is of high relevance. In this study the ability of grip force measurements of different grip forms was evaluated to discriminate between a simulated median nerve lesion and healthy subjects., Material and Methods: In 21 healthy subjects, the grip force of power grip was measured by the JAMAR dynamometer at the second stage including measurement of force at the fingertips and the thenar by a sensor glove. With a pinch dynamometer the power of palmar abduction, precision grip, pincer grip and pinch grip was determined. Measurements were performed with and without median nerve block at the wrist., Results: In power grip of the JAMAR dynamometer at the second stage a significant reduction of the grip force of 13.4% was found (p < 0.03). The power distribution between the fingers D2-D5 did not change with median nerve block. The most relevant reduction of grip force in median nerve block compared with the healthy control was measured in palmar abduction (72.1%, p < 0.0002), followed by precision grip 31.0% (p < 0.0001), pincer grip 23.6% (p < 0.0004) and pinch grip 18.8% (p < 0.0002)., Conclusions: For the discrimination between healthy subjects and subjects with a median nerve block there was a limited relevance of the measurement of the power grip and force distribution at the fingers by the JAMAR dynamometer. However, the best distinction was observed by dynamometric measurement of other grips than power grip, such as palmar abduction, precision grip, pincer grip and pinch grip. The results could be relevant for the clinical diagnostics and rehabilitation of median nerve lesion, complementing the widespread measurement of the power grip by other grip forms.

Ulnar nerve injuries can cause deficient hand movement patterns. Their assessment is important for diagnosis and rehabilitation in hand surgery cases. The purpose of this study was to quantify the changes in temporal coordination of the finger joints during different power grips with an ulnar nerve block by means of a sensor glove. In 21 healthy subjects, the onset and end of the active flexion of the 14 finger joints when gripping objects of different diameters was recorded by a sensor glove. The measurement was repeated after an ulnar nerve block was applied in a standardized setting. The change in the temporal coordination of the metacarpophalangeal (MCP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints with and without the nerve block was calculated within the same subject. In healthy subjects, the MCP joints started their movement prior to the PIP joints in the middle and ring finger, whereas this occurred in the reverse order at the index and little finger. The DIP joint onset was significantly delayed (P<0.01). With the ulnar nerve block, this coordination shifted towards simultaneous onset of all joints, independent of the grip diameter. The thumb and index finger were affected the least. With an ulnar nerve block, the PIP joints completed their movement prior to the MCP joints when gripping small objects (G1 and G2), whereas the order was reversed with larger objects (G3 and G4). The alterations with ulnar nerve block affected mainly the little finger when gripping small objects. With larger diameter objects, all fingers had a significant delay at the end of the PIP joint movement relative to the MCP and DIP joints, and the PIP and DIP joint sequence was reversed (P<0.01). Based on the significant changes in temporal coordination of finger flexion during different power grips, there are biomechanical effects of loss of function of the intrinsic muscles caused by an ulnar nerve block on the fine motor skills of the hand. This can be important for the diagnosis and rehabilitation of ulnar nerve lesions of the hand., (Copyright © 2017 SFCM. Published by Elsevier Masson SAS. All rights reserved.)

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., (Copyright © 2016 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.)

In the assessment of hand and upper limb function, detecting sincerity of effort (SOE) for grip strength is of major importance to identifying feigned loss of strength. Measuring maximal grip strength with a dynamometer is very common, often combined with calculating the coefficient of variation (CV), a measure of the variation over the three grip strength trials. Little data is available about the relevance of these measurements in patients with median nerve impairment due to the heterogeneity of patient groups. This study examined the reliability of grip strength tests as well as the CV to detect SOE in healthy subjects. The power distribution of the individual fingers and the thenar was taken into account. To assess reliability, the measurements were performed in subjects with a median nerve block to simulate a nerve injury. The ability of 21 healthy volunteers to exert maximal grip force and to deliberately exert half-maximal force to simulate reduced SOE in a power grip was examined using the Jamar ® dynamometer. The experiment was performed in a combined setting with and without median nerve block of the same subject. The force at the fingertips of digits 2-5 and at the thenar eminence was measured with a sensor glove with integrated pressure receptors. For each measurement, three trials were recorded subsequently and the mean and CV were calculated. When exerting submaximal force, the subjects reached 50-62% of maximal force, regardless of the median nerve block. The sensor glove revealed a significant reduction of force when exerting submaximal force (P1 sensor) with (P<0.032) and without median nerve block (P<0.017). An increase in CV at submaximal force was found, although it was not significant. SOE can be detected with the CV at the little finger at using a 10% cut-off (sensitivity 0.84 and 0.92 without and with median nerve block, respectively). These findings suggest low reliability of the power grip measurement with the Jamar ® dynamometer, as well as that of the CV for detecting SOE. However, the combination of finger forces including the thenar area and the CV at the little finger could lead to better reliability for detecting feigned reduction of grip strength. The methods were as reliable in subjects with a median nerve block as in healthy subjects., (Copyright © 2017 SFCM. Published by Elsevier Masson SAS. All rights reserved.)

Background: Wrist fusion is still a common treatment for patients with advanced stage arthritis. Since patients are often intimidated by the functional limitations, we intended to evaluate the influence of the lack of wrist motion in different positions on the dynamic grip function and the grip strength of the hand., Methods: We simulated wrist fusion in 20° extension and 20° flexion and evaluated the following grip types: fist closure, 2 different power grips, pinch grip and precision grip. A TUB sensor glove was used, which allowed us to dynamically record the range of motion (ROM) of the finger joints as well as grip strength. Nineteen healthy subjects participated and all types of grips were performed using a standardised protocol with and without simulated wrist fusion., Results: Lack of wrist motion in 20° extension had no relevant effect on the fingers' ROM, grip speed or strength. Simulated fusion in 20° flexion also had no influence on ROM or grip speed, rejecting our hypothesis that a tenodesis effect of the extensors in flexion would decrease ROM in the finger joints and grip speed. However, we were able to show a significant decrease of grip strength in flexion compared with extension or healthy wrists. The decrease averaged between 23 and 42% of healthy values, depending on the grip type. There was no change in strength distribution among the fingers., Conclusion: We didn't find any impact of lack of wrist motion on finger movement during forceful hand grip at normal speed. However, a significant loss of grip strength in flexed position of the wrist joint should be considered in patients with an indication for bilateral wrist fusion., (© Georg Thieme Verlag KG Stuttgart · New York.)

The purpose of this study was to assess whether there is a universal pattern of movement of the finger joints while performing a cylinder grip. A sensor glove was used to record the finger joint motion of 48 participants. Our observations showed that when examining the fingers, flexion motion began either at the metacarpophalangeal (MP) or proximal interphalangeal (PIP) joints, with the distal interphalangeal (DIP) joints always last to move (p = 0.0052). The sequence of the joints at the end of the gripping motion was different than at the beginning. Here, the only statistically significant observation was that the DIP joints fully flexed only once the MP joints had flexed fully. Apart from that, it was completely variable which joint reached its final position first or last. The analysis also revealed that synchronization of four identical joints (i.e. the four PIP joints) was significantly higher than synchronization of the 12 finger joints. Although synchronization was already high at the beginning of the flexion motion, it increased significantly by the time the joints completed their movement.

The purpose of this study was to analyse motion patterns of the finger joints dynamically while making a fist. 10 subjects were examined using the TUB-sensor glove, which was equipped with 14 joint angle sensors. The median time it takes the finger joints to complete flexion until reaching the state of a closed fist ranges between 0.5 to 1.0 s. A specific pattern can be seen for every finger. The PIP and DIP joints appear to be linked, with the DIP trailing the PIP joint. At the thumb the IP is trailing the MCP joint. The MCP joint shows more variation at the beginning of flexion: while in some cases it initiates movement in a finger, in other cases its flexion falls behind the PIP joint movements. The completion of flexion is achieved by the MCP joints, with the PIP and DIP joints reaching their end of motion first. The range of motion (ROM) at the MCP joints shows a finger-dependent median of 79-97°. At the PIP joints the median lies between 87° and 90°, at the DIP joints between 52° and 68°. At the thumb it is 21° for the MCP and 24° for the IP joint. The linkage between PIP and DIP joints can also be seen when analysing the ROM. The coupling ratio amounts to 0.77 at the index finger, 0.75 at the middle and ring finger and 0.57 at the small finger., (© Georg Thieme Verlag KG Stuttgart · New York.)

The present study analyses force distribution patterns during primary grips. 10 subjects were examined using the TUB-sensor glove, which was equipped with 10 pressure sensors. 5 proximal sensors at the MCP joints and 5 distal sensors at the DIP joints were attached palmarly. 9 different gripping motions were examined: the cylinder grip using 4 different objects, the pinch grip and 4 different kinds of precision grips. The force distribution patterns can be clearly divided into 2 groups. On the one hand there are the "power grips", in which the force is distributed over the proximal and distal sensors. On the other hand there are the "precision grips", which only show a force distribution at the distal sensors. Therefore Napier's concept of the existence of primarily 2 gripping patterns, which is based on visual analysis, can be verified objectively. For the "power grips" the force distribution is shifted further distally with increasing size of the objects. In conclusion, their distribution pattern shifts towards the pattern of the "precision grips". At the small finger the distal sensor is already dominant during the "power grips" of smaller objects. The thumb plays a subordinate role during the "power grip" of smaller objects, since these grips are similar to the "closing fist motion" and the objects can be held between the fingers and the palm of the hand. However, with increasing object sizes the thumb gains more importance, since its opposing movement is now required to accomplish the grip., (© Georg Thieme Verlag KG Stuttgart · New York.)

Purpose: To determine whether the grip of a healthy subject's hand shows certain universal characteristics. To accomplish this, we examined the complex interactions of the fingers during gripping of different-size cylindrical objects., Methods: A total of 48 subjects (11 women, 37 men) performed 5 cylinder grips with different object sizes. The 14 joint angular profiles of the 5 digits were measured dynamically with a Technische Universität Berlin sensor glove., Results: Frequently, initial movement was detected before the actual grip. This movement consisted of passive flexion of the fingers the moment the hand rose from the table, followed by active extension of the fingers before gripping the object. Along with the type of joint, the size of the object gripped influenced the frequency of these initial movements (p<.001). During actual grip, the proximal interphalangeal joints' flexion was significantly greater than the flexion of the metacarpophalangeal and distal interphalangeal joints (p<.001). The mean flexion of the proximal interphalangeal joints was 43 degrees , that of the metacarpophalangeal joints was 28 degrees , and that of the distal interphalangeal joints was 26 degrees. Apart from these findings, the larger the flexion angle was, the more time tended to be needed to fulfil the motion., Conclusions: The results show that there is a universal motion pattern with the cylinder grip in healthy individuals concerning the range of movement of the finger joints. However, to fully understand the cylinder grip in healthy individuals, our next step will be to analyze the dynamics of the cylinder grip as well. For that purpose, we examine the dynamic interactions between the fingers--that is, their chronological sequence during the cylinder grip., (Copyright 2010 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.)

This study examined patterns of grip strength when maximal and submaximal effort are applied. Using a sensor glove, 50 healthy subjects performed two different power grips. Both maximal and submaximal gripping showed characteristic patterns of strength distribution that were independent of the degree of power applied. Significant differences were also noted in the strength distribution patterns, depending on whether the grip was performed at maximal, or submaximal, strength. The small finger plays a decisive role in this. In maximal strength gripping, the total measured strength is distributed relatively evenly over all four fingers, with each finger contributing between 23% and 27% of the total strength. In submaximal strength gripping, the little finger is involved very little and only contributes between 14% and 15% of the total strength, with the remainder of the gripping distributed relatively evenly between the index, middle and ring fingers, each of which contributes between 26% and 32% of the total.

Grip strength measurements with the aid of dynamometers are dependent on the cooperation and motivation of the individual examined. Recognising a simulated loss of grip is a hitherto unresolved problem. With a sensor glove developed at the Berlin University of Technology, the force distribution pattern of any form of grip can be captured via ten pressure sensors and evaluated by computer. In five subjects, the force distribution patterns at submaximum and maximum force of five different grips were determined in three successive measurements each. The data were recorded in force-time diagrams. For each act of grasping, the measurements produced a curve with near-constant measuring signals within a defined period (plateau). The difference in the plateau heights of successive grips and the structures of the individual plateaux (oscillation, standard deviation) were used as distinguishing criteria. The dynamics of the measuring signals showed statistically significant differences between grips with submaximum and maximum force (p < 0.0001).