Degrees Of Wrist Extension Research Articles

The Effect of Forearm Shortening on Finger Flexion: A Biomechanical Study

Surgeons may shorten the forearm for many indications. We quantified the impact of shortening on finger flexion with a cadaver model. Ten fresh cadaver proximal forearms were pinned to a static block. We pinned each distal forearm/hand to a block that could unlock, slide, and relock on a mounting track. This block allowed wrist-neutral or 30-degree extension. With the sliding block locked, we removed the central 10 cm of the radius/ulna. We placed sutures in the proximal end of each flexor digitorum profundus (FDP). After pretensioning, we simulated near-maximum baseline FDP muscle-generating force by applying 100 N via a load cell at the proximal sutures. We then anchored the load cell system proximally to set the initial length-tension relationship for simulating near-maximum baseline muscle-generating force. We called subsequent load cell readings the simulated muscle force (SMF) and pressure sensor readings between fingertips and the palm the tip-to-palm force (TPF). We shortened the forearm in 1 cm increments with the distal sliding-locking block. At each increment, we recorded SMF and TPF in the wrist-neutral position. Once a specimen lost measurable TPF, we applied 30 degrees wrist extension until again losing TPF. Incremental forearm shortening was associated with exponential decreases in each FDP's SMF and TPF. In wrist-neutral, 3 cm mean shortening had a loss of 99% and 98% SMF and TPF, respectively. Wrist extension marginally improved SMF and TPF up to 4 cm mean shortening, where both lost 99%. Loss of any fingertip touchdown occurred after a mean shortening of 4.9 cm in wrist-neutral and 5.3 cm in 30 degrees wrist extension. Mean forearm shortening of 3 or 4 cm had a near-complete loss of FDP SMF and TPF in wrist-neutral/wrist extension, respectively. With ∼5 cm shortening, there was a complete loss of fingertip touchdown. Surgeons should consider the influence of forearm shortening on the FDPs and contemplate flexor tendon shortening or alternative reconstructions as indicated.

Evaluation of the Effect of Ununion Percentage of Scaphoid on Stress and Displacement of Fragment Part of Scaphoid in Various Degrees of Wrist Extension with and without External Force

Abstract Background Scaphoid fractures are almost two-thirds of different kinds of carpal fractures. Surgeons usually have challenges in deciding if the wrist should be mobilized or immobilized for the patients with different percentiles of partial union of scaphoid. This study's aim was to investigate different percentiles of union (25–50–75) in waist and proximal pole of scaphoid fracture to find the union percentile which can tolerate normal daily activities to help surgeons in taking appropriate decisions in this regard. Method A model of wrist joint was developed in this study based on computed tomography scan images of wrist joint. Various percentage of union in waist and proximal poles of scaphoid with and without internal fixation were tested in this study. The stress applied on scaphoid and displacement of fragment parts were evaluated in Abaqus software during motion of wrist from neutral to 40 degrees of extension. Results Although Von Mises stress of scaphoid bone increased following use of external force, the difference was significant for conditions 3 and 6 (75% of union in middle and distal parts). The stress applied on scaphoid increased depends on conditions (ununion percentage of bone). Moreover, its stress depends on the angle of wrist extension. Use of internal fixation screw decreased stress of scaphoid in most of conditions. Conclusion The stress developed in scaphoid depends on the nonunion percentage of scaphoid and the amount of motion of wrist joint. It is better to use external fixation screw especially for conditions 3 and 6 (75% of union in middle and distal parts) to decrease the displacement of fragment parts and to decrease the stress applied on scaphoid in wrist extension. Type of Study and Level of Evidence Case study, level of evidence: III.

The efficacy of ultrasound and low-intensity laser therapy in carpal tunnel syndrome

Aim: The most frequent type of peripheral entrapment neuropathy is carpal tunnel syndrome (CTS), which is caused by compression of the median nerve at the wrist level. Ultrasound (US) and low-intensity laser therapy (LILT) are among the most commonly used physical therapy methods in the treatment of CTS. The aim of this study is to examine the efficacy of US and LILT in the treatment of CTS and their superiority to each other.
 Material and Method: Patients who were admitted to the physical therapy program with the diagnosis of CTS in our clinic were retrospectively examined. A total of eleven patients (18 wrists) diagnosed with mild and moderate CTS were included in our study with the G-Power program with a 5 % margin of error and 80 % power. Patients were divided into US and LILT groups using a simple randomization method. The patients were evaluated in terms of clinical and electrophysiological parameters before and after treatment.
 Results: A total of 18 wrists were included in our study, of which eight patients were diagnosed with mild CTS and the rest (n=10) with moderate CTS. The mean age of the patients was 49.66±10.68 years. When the post-treatment clinical (Boston Carpal Tunnel Syndrome Questionnaire (BCTQ), hand and pinch grip strength, measurement of wrist joint range of motion) and electrophysiological parameters were evaluated between the US and LILT groups, no significant difference was found in terms of their superiority over each other (p>0.05). When the LILT group was compared before and after treatment, a statistically significant difference was found in the degree of wrist extension, handgrip strength and BCTQ parameters. (p

Evaluation of Dynamic Carpal Arch Stability following Carpal Tunnel Release Using Four-Dimensional Computed Tomography

Introduction This study aimed to assess the carpal arch dynamics during active finger and wrist motion following carpal tunnel release using four-dimensional computed tomography (4D-CT).Materials and Methods Four patients who diagnosed with bilateral carpal tunnel syndrome and underwent unilateral carpal tunnel release were prospectively included. 4D-CT of the bilateral wrists during active finger and wrist motion was performed for 10 seconds at five frames per second. The distances between the tip of tuberosity of the scaphoid and the volar ridge of the pisiform (S–P distance) and volar ridge of trapezium and the tip of hook of hamate (T–H distance) were measured at each position and the values of S–P and T–H distances were compared between the postoperative and contralateral wrists.Results During finger motion, the S–P and T–H distances were not different at any position between the postoperative side and contralateral side. Conversely, S–P and T–H distances gradually increased in the postoperative wrists. The differences between the sides of S–P distance were significant, with >0 degrees of wrist extension, and differences of T–H distance were significant with >15 degrees of wrist extension.Conclusion This study demonstrated the carpal arch dynamics using 4D-CT and revealed that the carpal arch was widened with the wrist in extension after carpal tunnel release. This study suggests that the transverse carpal ligament plays an important role in maintaining carpal arch stability.

Changes in the pressure distribution by wrist angle and hand position in a wrist splint

The study was conducted to provide basic data to develop a system that distributes pressure over a broader area by measuring and analyzing pressures in various wrist angles and hand positions while wearing a wrist splint. With 0, 15, 30, and 45 degrees of wrist extension, full-finger extension and finger flexion, pressure distribution changes were measured three times. Average peak pressure was analyzed and mean value picture (MVP) in zones 3–5 was calculated. A one-way Anova was conducted to identify changes in pressure distribution by wrist angle and hand position. Mean peak pressure values (kPa) in zones 3–5 changed depending on the wrist angle. Peak pressures (kPa) changed significantly in 15, 30, and 45 degrees wrist extension, depending on the hand position. Since pressure distributions differ depending the wrist angle and hand position (finger flexion), it is necessary to consider how pressure varies in each wrist position and to provide information on postures that should be avoided during tasks and occupational activities based on various wrist angles or hand positions.

Ultrasound evaluation of effect of different degree of wrist extension on radial artery dimension at the wrist joint.

Context:Successful arterial cannulation requires wide and patent arterial lumen. A recent study has shown that success rate of radial arterial cannulation at first attempt is more at 45° angle of wrist extension in both young and elderly patients. No study has reasoned whether these high success rates at 45° is because of less compression of the radial artery at this particular angle of wrist extension. Hence, we attempted to study whether the radial artery dimensions changes with increasing angles of wrist extension in young, healthy female volunteers using ultrasound examination.Aim:To investigate the effect of increasing angle of wrist extension of 0, 15, 30, 45, 60, and 75° on radial artery dimensions at the level of the wrist joint using ultrasound examination.Settings and Design:A prospective single blinded study in volunteers.Subjects and Methods:Sonographic measurements of radial artery dimension at the wrist level were performed in 48 young, healthy female subjects. Height (anteroposterior in mm), width (mediolateral in mm) and depth (skin to artery) were measured at wrist extension of 0, 15, 30, 45, 60, and 75°. The dimensions at each angle are compared with 0° as the control and statistical analysis done.Statistical Analysis:One-way analysis of variance test.Results:No statistically significant change in dimension of the radial artery is observed with increasing angle of wrist extension.Conclusion:Ultrasound evaluation showed that increasing angle of wrist extension does not significantly change the dimensions of radial artery at the wrist joint level in young healthy female volunteers.

Wrist Biomechanics In Yoga: Level 4 Evidence

In a survey of yoga professionals, the wrist accounted for 11.5% of reported injuries. The purpose of this study was to evaluate how modifications may decrease strain and prevent injury in three common yoga positions- downward dog (DD), chaturanga (Ch), and side plank (SP). The participants were 43 healthy volunteers, 23 females and 20 males. Mean age was 27 years. Peak pressure, maximum force and load distribution were measured in standard and modified positions in DD, Ch, and SP using a pressure-measuring device. Wrist extension was also measured in these same positions. Modification to the DD position consisted of placing the palms on an elevated platform. Ch and SP were modified by permitting the participants to have their knees on the floor rather than balance on their toes. Modified positions shifted the center of gravity further toward the lower torso, decreasing both load forces on the wrist and degree of wrist extension. A two-way ANOVA was performed to assess the effect of standard and modified positions on peak pressures. Peak pressures decreased from 379.4 to 308 kPa and 483.1 to 401.9 kPa in the modified Ch and SP positions, respectively (P < 0.001). The modifications in DD did not significantly affect the peak pressure (P = 0.713). Similarly, maximum force was decreased in modified Ch and SP positions, with Ch decreasing from 290.0 to 244.2 N and SP from 433.0 and 360.1 N (P < . 001). The modifications in DD did not significantly affect maximum force (P = 0.518). Analysis of load distribution mapping showed that peak pressure and maximum force were highest in the thenar area in the palms in DD and SP positions. In Ch, peak pressure and maximum force were highest in the hypothenar area. The angle of wrist extension increased in Ch and SP from 70.3 to 70.7 and 82.3 and 83.3. Wrist extension decreased in the DD position from 57.5 to 52.0. •Modified SP and CH yoga positions resulted in a significant decrease in peak pressure and maximum forces by shifting the center of gravity toward the lower torso.•Modifications to the DD pose resulted in a significant decrease in wrist extension angle potentially adding protective benefits.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Design and Assessment of Ergonomics of Hand-Powered Pruning Shears Based On Gender-Specific Operating Strategy

The present study investigated the biomechanical and physiological loads when working with pruning shears of varying design. The objective of this study was to find usability issues on conventional pruning shears and integrate ergonomics into the design process to improve users’ safety and health as well as performance. Effects of pruning shear design, gender, and hand size on muscle activities, grip force distribution, wrist deviations, and gender-specific operating strategy were studied in six male and six female participants while cutting wooden dowels with pruning shears. Three types of pruning shears were used, one conventional and two modified, either with a rubber grip-padded, or with a thumb grip attached to the upper handle. The results showed that (1) the two redesigned pruning shears minimized pressures on some critical hand regions and improved muscle activities, grip force distribution, and wrist deviations and (2) a large degree of wrist extension, greater use of the extensor digitorum (ED) ...

Grip strength measurements at two different wrist extension positions in chronic lateral epicondylitis-comparison of involved vs. uninvolved side in athletes and non athletes: a case-control study

BackgroundLateral epicondylitis is a common sports injury of the elbow caused due to altered muscle activation during repetitive wrist extension in many athletic and non-athletic endeavours. The amount of muscle activity and timing of contraction eventually is directly dependent upon joint position during the activity. The purpose of our study was to compare the grip strength in athletes with lateral epicondylalgia in two different wrist extension positions and compare them between involved and uninvolved sides of athletes and non-athletes.MethodsAn assessor-blinded case-control study of eight athletes and twenty-two non-athletes was done. The grip strength was measured using JAMAR® hand dynamometer in kilograms-force at 15 degrees (slightly extended) and 35 degrees (moderately extended) wrist extension positions (maintained by wrist splints) on both involved and uninvolved sides of athletes and non-athletes with unilateral lateral epicondylitis of atleast 3 months duration. Their pain was to be elicited with local tenderness and two of three tests being positive- Cozen's, Mill's manoeuvre, resisted middle finger extension tests. For comparisons of grip strength, Wilcoxon signed rank test was used for within-group comparison (between 15 and 35 degrees wrist extension positions) and Mann-Whitney U test was used for between-group (athletes vs. non-athletes) comparisons at 95% confidence interval and were done using SPSS 11.5 for Windows.ResultsStatistically significant greater grip strength was found in 15 degrees (27.75 ± 4.2 kgms in athletes; 16.45 ± 4.2 kgms in non-athletes) wrist extension than at 35 degrees (25.25 ± 3.53 kgm in athletes and 14.18 ± 3.53 kgm in non-athletes). The athletes had greater grip strength than non-athletes in each of test positions (11.3 kgm at 15 degrees and 11.07 kgm at 35 degrees) measured. There was also a significant difference between involved and uninvolved sides' grip strength at both wrist positions (4.44 ± .95 kgm at 15 degrees and 4.44 ± .86 kgm in 35 degrees) which was significant (p < .05) only in non-athletes.ConclusionThe grip strength was greater in 15 degrees wrist extension position and this position could then be used in athletes with lateral epicondylalgia for grip strength assessment and designing wrist splint in this population.

Short Range of Motion Isokinetic Testing of Wrist Flexor and Extensor Strength in Normal Subjects and Patients with Carpal Tunnel Syndrome

The purpose of this study was to compare the utility of measuring wrist flexors and extensors strength derived from 'full' range of motion (FRoM): 60 degrees of flexion to 30 degrees of extension, and 3 equally spaced short ranges of motion: SRoM1, 60-30 degrees and SroM2, 30-0 degrees of flexion and SRoM3, 0-30 degrees of wrist extension. Fifteen apparently healthy subjects and 8 patients suffering from unilateral carpal tunnel syndrome (CTS) participated in the study. In all participants, SRoM1 findings closely resembled those obtained from FRoM. In the patient groups, the muscular strength of the uninvolved side was not different from that of the healthy subjects. On the other hand, based on a bilateral comparison (involved vs. uninvolved hand), the mean total weakness (in concentric and eccentric modes) was significantly higher in flexion (56.4 +/- 17.3%) than in extension (39.8 +/- 15.5%) but highly symmetrical between FRoM and SRoM1. Although supporting the interchangeable use of FRoM and SRoM isokinetic testing, this study highlights a hitherto unreported dynamic weakness of the wrist extension-flexion apparatus that may partly account for the general reduction in hand function reported by patients with CTS.

Shear Strain and Motion of the Subsynovial Connective Tissue and Median Nerve During Single-Digit Motion

The objective of this study was to measure the relative motion of the middle finger flexor digitorum superficialis (FDS) tendon, its adjacent subsynovial connective tissue (SSCT), and the median nerve during single-digit motion within the carpal tunnel in human cadaver specimens and to estimate the relative motions of these structures in different wrist positions. Using fluoroscopy during simulated single-digit flexion, we measured the relative motion of the middle finger FDS tendon, SSCT, and median nerve within the carpal tunnel in 12 human cadavers. Measurements were obtained for 3 wrist positions: neutral, 60 degrees flexion, and 60 degrees extension. After testing with an intact carpal tunnel was completed, the flexor retinaculum was cut with a scalpel, and the same testing procedure was repeated for each wrist position. The relative motions of the tendon, SSCT, and median nerve were compared using a shear index, defined as the ratio of the difference in motion along the direction of tendon excursion between 2 tissues divided by tendon excursion, expressed as a percentage. Both tendon-SSCT and tendon-nerve shear index were significantly higher in the 60 degrees of wrist flexion and extension positions than in the neutral position. After division of the flexor retinaculum, the shear index in the 60 degrees wrist extension position remained significantly different from that of the neutral position. We have found that the relative motion between a tendon and SSCT in the carpal tunnel is maximal at extremes of wrist motion. These positions may predispose the SSCT to shear injury.

A study of constraint-induced movement therapy in subacute stroke patients in Hong Kong

Objective: To investigate the beneficial effect of constraint-induced movement therapy in improving the function of hemiplegic upper extremity in the early subacute stroke patients. Design: A prospective, single-blinded, randomized controlled study comparing the effectiveness of constraint-induced movement therapy or control treatment at post intervention and 12 weeks follow-up. Subjects: The inclusion criteria were 2—16 weeks after stroke, hemiparesis of the affected limb, minimal function of ≥20 degrees wrist extension and ≥10 degrees extension of all digits and Mini-Mental State Examination score ≥17. Interventions: The intervention group underwent a programme of 10 days upper extremity training (4 hours per day) with the unaffected limb being restrained in a shoulder sling and the control group received an equivalent duration of conventional rehabilitation therapy. Main measures: Functional level for hemiparetic upper extremity, Motor Activity Log, Action Research Arm Test and modified Barthel Index. Results: There were 23 and 20 subjects respectively in the constraint-induced movement therapy and control groups. Significant improvements were seen at post intervention and 12 weeks after constraint-induced movement therapy in functional level for hemiparetic upper extremity (P= 0.001), and in the `amount of use' (P= 0.001) and `how well' (P= 0.021) subscales of the Motor Activity Log. The total Action Research Arm Test score, grasp (P= 0.004), grip (P= 0.004), pinch (P= 0.032) and gross (P= 0.006) components showed significant improvement over the control group at post intervention. The grip component (P=0.019) and the total Action Research Arm Test score (P= 0.009) were superior to the control group at 12 weeks. Conclusion: Significant improvement in hand function could be achieved with constraint-induced movement therapy in subacute stroke patients, which was maintained up to 12 week follow-up.

Trimed Fixation System for Displaced Fractures of the Distal Radius

To study the functional outcome of displaced distal radius fractures treated by open reduction and internal fixation with the use of fragment-specific fixation. Fifteen consecutive displaced distal radius fractures (5 extra-articular and 10 intra-articular) were treated using the Trimed distal radius fixation system (Trimed, Valencia, CA). Radiographic assessment and range of motion of the affected wrist were evaluated postoperatively. Functional outcomes were evaluated with use of the Disabilities of the Arm, Shoulder, and Hand questionnaire and the Gartland and Werley scoring system. The mean follow-up was 11 months. The patients initiated controlled passive and active motion exercises during the first week. The mean score on the Disabilities of the Arm, Shoulder, and Hand questionnaire was 16 points. The mean return to work was 12 weeks. The functional outcome was 80% excellent or good by the Gartland and Werley scoring system for intra-articular fractures and 80% excellent for extra-articular fractures. Range of active motion in intra-articular fractures was measured 60 degrees wrist extension, 64 degrees flexion, 65 degrees pronation, and 70 degrees supination, and for extra-articular fractures, 75 degrees extension, 70 degrees flexion, 80 degrees pronation, and 75 degrees supination. There was failure of fixation with loss of the reduction that was achieved at the time of operation in one patient. Fragment-specific fixation of unstable distal radius fractures using the Trimed system appears to be effective. Anatomic reduction, earlier range of motion, and improved functional results can be achieved using low-profile implants.

Temporal uncertainty does not affect response latencies of movements produced during startle reactions

Previous research has shown that a startle 'go' stimulus, presented at a constant latency with respect to a warning stimulus, is capable of eliciting an intended voluntary movement in a simple reaction time (RT) task at very short latencies without involvement of the cerebral cortex (Carlsen et al. in Exp Brain Res 152:510-518, 2003; J Motor Behav 36:253-264, 2004a; Exp Brain Res 159:301-309 2004b; Valls-Solé et al. in J Physiol 516:931-938, 1999). The purpose of the present experiment was to determine the effect of temporal uncertainty on response latency during an RT task that comprised a startle stimulus. Participants were required to perform an active 20 degrees wrist extension movement in response to an auditory tone that was presented 2,500 to 5,500 ms after a warning stimulus, in 1,000 ms increments. On certain trials the control auditory stimulus (80 dB) was unexpectedly replaced by the startle stimulus (124 dB). When participants were startled the intended voluntary movement was initiated at approximately 70 ms, regardless of foreperiod duration. The magnitude and invariance of response latencies to the startle stimulus suggest that the intended movement had indeed been prepared prior to the arrival of the imperative go stimulus, within 2.5 s of the warning stimulus. Furthermore, there was no evidence that the prepared movement decayed over a period of at least 3 s.

Concurrent changes in shortening reaction latency and reaction time of forearm muscles in post-stroke patients

The objective was to confirm the hypothesis that shortening reaction (ShoRe), normally occurring on forcibly shortening a muscle, is depressed or delayed in post-stroke patients. Eight post-stroke patients and ten age-matched normal subjects had a 50 degrees wrist extension or flexion induced by a torque-motor in the affected and the non-affected upper limb. Patients were instructed either not to intervene or to assist displacement (reaction-time condition, RT). Frequency of occurrence and latency of stretch reflex (SR) and ShoRe, and RTs were measured from the electromyograms (EMG) of wrist flexor (FCR) and extensor (ECR) muscles. SR had higher than normal frequency in both muscles. ShoRe disappeared in ECR on the affected side but had normal frequency in FCR of both sides. ShoRe latency was prolonged in FCR and ECR, in both affected and unaffected sides. RTs were prolonged in both FCR and ECR, in both affected and unaffected sides. Across all patients, RTs and ShoRe latencies in the FCR were correlated. Neither RTs nor ShoRe latencies were correlated to Ashworth score. RTs were inversely correlated to Medical Research Council scores. The decreased and delayed ShoRe in post-stroke patients supports a role for the cortico-spinal pathway in its production or modulation. Monitoring of ShoRe can give insight into the recovery of the descending control of spinal reflexes.

The effect of division of the transverse carpal ligament on flexor tendon excursion

The effect of the transverse carpal ligament (TCL) as a pulley was evaluated by measuring flexor tendon excursion after ligament division and by changing wrist position through a range of flexion and extension. Eight fresh cadaver upper extremities were mounted in a device and tendon excursions from full extension to fingertip-palm contact were measured for each flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) tendon. Measurements were performed with the wrist at 30 degrees extension, neutral, 30 degrees flexion, and 60 degrees flexion. The TCL was then sectioned, the skin was sutured, and the measurements were repeated. Two forms of carpal ligament repair were then done--transposition flap and aponeurotic repairs--and measurements were again repeated. With increasing wrist flexion, greater excursion differences were noted. Analysis of variance revealed that for both FDS and FDP, a significant difference in excursion occurred at 60 degrees wrist flexion and 30 degrees wrist extension with no ligament reconstruction or aponeurotic repair, compared to values prior to carpal tunnel release (p < .05) and to transposition ligament repair (p < .05).

The Application of Force to the Healing Tendon

This paper redefines the term “active motion” in postoperative tendon management programs as “minimal active muscle-tendon tension” (MAMTT), and reports a study of internal forces applied to a repaired tendon with MAMTT, with specific guidelines for joint angle and external load application, that allows a repeatable and reliable technique for the application of active stress to a healing tendon repaired with some currently available popular suture techniques. A comparative analysis of the reported tensile strengths of 28 different repair techniques comparing methods of study with conversion of newtons to grams provides the therapist easy access to a workable equation for force application being less than the tensile strength of any specific repair. The “active” hold pOsition or MAMTT for the digital flexor system is calculated mathematically, with drag eliminated, and joint angle position of 45 degrees wrist extenSion, metacarpophalangeal joint flexion of 83 degrees, proximal interphalangeal joint flexion of 75 degrees, and distal interphalangeal joint flexion of 40 degrees, and an external load applied at the fingertip of 50 grams. In this position, the internal force on the flexor digitorum profundus is 41 grams, and that on the flexor digitorum superficial is is 605 grams. These forces dramatically increase as joint angles become greater, creating forces that exceed the tensile strengths of most repairs. Internal forces along the extensor system are calculated mathematically at approximately 300 grams when the wrist is positioned at 20 degrees of flexion, and the digital joints at a position of 0 degrees of extension in an active hold position. Postoperative management of the repaired flexor or extensor tendon with immediate active motion described as MAMTT is supported by a clinical review of 165 tendons treated with this technique.

The relationship between wrist position, grasp size, and grip strength

In the first part of this study, the position assumed by a normal wrist during unconstrained maximal grip and the relationship between wrist position and grip strength were investigated in 20 healthy subjects. Grip strength and wrist position were recorded in the self-selected position and then again while the subjects voluntarily deviated the wrist randomly into flexion, extension, or radial or ulnar deviation of 10 to 15 degrees. The self-selected position was 35 degrees of extension and 7 degrees of ulnar deviation. Grip strength was significantly less in any position of deviation from this self-selected position, even after accounting for fatigue. With the wrist in only 15 degrees of extension or in neutral radio-ulnar deviation, grip strength was reduced to two thirds to three fourths of normal. Sex did not affect wrist position. The dominant wrists were within 5 degrees of the nondominant ones but were relatively less extended and in more ulnar deviation. Grip strength is significantly reduced when wrist position deviates from this self-selected optimum position. In the second part of the study, the effect of grasp size on this self-selected position was studied in 21 subjects. The degree of wrist extension was inversely and linearly related to how large a setting on the Jamar dynamometer was used. This was true regardless of hand size, although the effect was more significant for smaller hands. Radial and ulnar deviations were not affected by handle position. A minimum of 25 degrees of wrist extention was required for optimum grip strength. Optimum wrist position (i.e., for grip strength only) for the dominant limb can be predicted within 5 degrees of that of the nondominant limb. Although the present data do not describe the optimum position for wrist fusion, they do describe the optimum position for grip strength in normal subjects and predict the effect of wrist position on such strength.