Congenital Palmar Duplication of the Index Finger: Ventral Polydactyly With Ventral Dimelia.

This report describes the case of a 10-month-old boy who presented with a duplicated index finger enveloped by palmar skin on the palmar side of the first web of the left hand. He was healthy without any other abnormalities except the hand anomaly. Surgical resection of the extra finger was performed with triangular flap at 15 months of age. The resected finger was composed of only palmar components: skin without nail or hair; flexor tendons; and digital nerves branching from the median nerve. Histological examination of the specimen demonstrated similar structures on both palmar and dorsal sides, that is, ridged, hairless, and glabrous skin with a high number of epithelial layers and thick corneous stratum and similar shaped tendons inserted into the symmetrical phalanx. This appears to be the first report in literature of an ectopic palmar index finger, a ventral polydactyly with ventral dimelia.

You may point, but do not touch: Impact of gesture-types and cognition on language in typical and atypical development.

BACKGROUND: Evidence shows that the relation with the referent (object manipulation, contact/no contact pointing) and the different hand features (index finger/open palm) when pointing indicate different levels of cognitive and linguistic attainment in typical development (TD). This evidences the close link between pointing, cognition and language in TD, but this relation is understudied in autism. Moreover, the longitudinal pathway these abilities follow remains unexplored and it is unclear what specific role (predictor or mediator) pointing and cognition have in both typical and atypical language development. AIMS: The first aim was to investigate whether pointing hand features (index finger/open palm) and relation with the referent (manipulation, contact and no contact pointing) similarly predict language in children with and without autism. The second aim was to explore whether cognition mediates the longitudinal relationship between pointing and language development. METHODS & PROCEDURES: Sixteen children with autism, 13 children at high risk (HR) for autism and 18 TD children participated in an interactive gesture-elicitation task and were tested on standardised cognitive and expressive language batteries in a longitudinal design. A two-step analysis consisted of a stepwise linear regression and mediation analyses. First, the linear regression identified which hand features and types of relation with the referent predicted expressive language in all groups. Second, three mediation analyses (one per group) assessed the predictor/mediator role of the variables that met significance in the regression analysis. OUTCOMES & RESULTS: Both cognition and index finger pointing were direct longitudinal predictors of further expressive language skills in the autism group. In TD and HR groups this relation was mediated by age. CONCLUSIONS & IMPLICATIONS: Findings highlight the role of age in communicative development, but suggest a key role of cognition and index finger use in the longitudinal relationship between pointing gestures and expressive language development in children with autism. This has important clinical implications and supports the view that index finger pointing production might be a useful tool in the intervention for communicative and language abilities in autism. WHAT THIS PAPER ADDS: What is already known on the subject There is evidence that no contact pointing is associated with complex socio-cognitive abilities that underpin communication in TD. Similarly, studies in TD show that index finger pointing is closely linked with language acquisition. However, it is unclear whether these associations are present in autism. In addition, the mediating (or predictive) role of cognition in the pointing-language relation has not yet been explored neither in typical nor in atypical development. What this paper adds to existing knowledge This paper shows that index finger pointing and cognition are direct longitudinal predictors of expressive language in the autism group. In the other groups this relation is mediated by age. This suggests that there is a window of opportunity for pointing to predict expressive language whereas the predictive value of cognition expands in development. Based on this, children with autism would share the same language predictors as TD children, but with delays. What are the potential or actual clinical implications of this work? This study reveals that index finger, age and cognition reliably predict spoken language in autism, which may indicate that early prelinguistic intervention based on pointing production and the improvement of cognitive skills might have a positive impact on spoken language in this population.

Innervation and vascular supply of the first dorsal interosseous muscle and palmar interosseous muscle of the index: An anatomic descriptive study.

INTRODUCTION: The first dorsal interosseous muscle (FDI) and palmar interosseous muscle of the index (P2I) are essential for the strength and mobility of the index finger. This study aims to describe the course of the deep branch of the ulnar nerve (DBUN) and the blood supply to these muscles. MATERIAL AND METHODS: An anatomical cadaver study was carried out with 14 upper limbs from fresh, non-embalmed cadavers. All limbs were filled with an equal amount, based on weight, of colored silicone and diluent that was combined and catalyzed with 5% curing agent. The location of the DBUN's termination was specified relative the carpometacarpal joint. Every artery supplying either muscle was identified and documented. RESULTS: The DBUN had a slightly convex path, distal to the hook of the hamate and penetrated the FDI muscle at an average 41% of the second metacarpal length. An average of 1.3 branches to the P2I and 2.6 branches to the FDI were found. Four artery pedicles coming from the deep palmar arch supply the FDI with an average of one consistent and exclusive pedicle to the FDI and three pedicles heading to the P2I. According to the classification of Mathes and Nahai, the FDI has a type 2 blood supply and the P2I has a type 3 blood supply. CONCLUSION: In-depth knowledge of the vascular network supplying the FDI and P2I muscles and the course of the DBUN is essential when the DBUN is damaged or when dissecting these muscles for index pollicization.

Modulation of finger muscle activation patterns across postures is coordinated across all muscle groups.

Successful grasp requires that grip forces be properly directed between the fingertips and the held object. Changes in digit posture significantly affect the mapping between muscle force and fingertip force. Joint torques must subsequently be altered to maintain the desired force direction at the fingertips. Our current understanding of the roles of hand muscles in force production remains incomplete, as past studies focused on a limited set of postures or force directions. To thoroughly examine how hand muscles adapt to changing external (force direction) and internal (posture) conditions, activation patterns of six index finger muscles were examined with intramuscular electrodes in 10 healthy subjects. Participants produced submaximal isometric forces in each of six orthogonal directions at nine different finger postures. Across force directions, participants significantly altered activation patterns to accommodate postural changes in the interphalangeal joint angles but not changes in the metacarpophalangeal joint angles. Modulation of activation levels of the extrinsic hand muscles, particularly the extensors, were as great as those of intrinsic muscles, suggesting that both extrinsic and intrinsic muscles were involved in creating the desired forces. Despite considerable between-subject variation in the absolute activation patterns, principal component analysis revealed that participants used similar strategies to accommodate the postural changes. The changes in muscle coordination also helped increase joint impedance in order to stabilize the end-point force direction. This effect counteracts the increased signal-dependent motor noise that arises with greater magnitude of muscle activation as interphalangeal joint flexion is increased. These results highlight the role of the extrinsic muscles in controlling fingertip force direction across finger postures.NEW & NOTEWORTHY We examined how hand muscles adapt to changing external (force direction) and internal (posture) conditions. Muscle activations, particularly of the extrinsic extensors, were significantly affected by postural changes of the interphalangeal, but not metacarpophalangeal, joints. Joint impedance was modulated so that the effects of the signal-dependent motor noise on the force output were reduced. Comparisons with theoretical solutions showed that the chosen activation patterns occupied a small portion of the possible solution space, minimizing the maximum activation of any one muscle.

Long-term practice of isolated finger movements reduces enslaved response of tonically contracting little finger abductor to tonic index finger abduction.

The purpose of this study was to elucidate whether the long-term practice of isolated finger movements reduces the enslaved response of the little finger abductor to the index finger abduction. The right-handed participants tonically or phasically abducted the index finger, while they maintained at rest or tonic abduction of the little finger. The enslaved response of the tonically contracting little finger abductor to the tonic abduction of the index finger was greater than the response of the same muscle at rest in the nonpianists. This indicates that the tonic contraction of the little finger abductor enhances the enslaving drive from the tonically contracting index finger abductor to the little finger abductor. The enslaved response of the tonically contracting little finger abductor to the tonic abduction of the index finger in the pianists was significantly smaller than that in the nonpianists, but such a significant group difference was absent when the little finger abductor was at rest. This indicates that the inhibitory process on the enslaving drive from the tonically contracting index finger abductor to the tonically active little finger abductor is unmasked through the long-term practice.

Traumatic index extensor tendon attenuation mimicking closed tendon rupture: two case reports.

BACKGROUND: While some traumatic closed index extensor tendon ruptures at the musclotendinous junction have been previously reported, closed index extensor tendon pseudorupture due to intertendinous attenuation is exceedingly rare with only one case report of a gymnastics-related sports injury in the English literature. Herein, we report two non-sports injury related cases of traumatic index extensor tendon attenuation mimicking closed tendon rupture, including the pathological findings and intraoperative video of the attenuated extensor indicis proprius tendon. CASE PRESENTATION: A 28-year-old man and a 30-year-old man caught their hands in a high-speed drill and lathe, respectively, which caused a sudden forced flexion of their wrists. They could not actively extend the metacarpophalangeal joints of their index fingers. Intraoperatively, although the extensor indicis proprius and index extensor digitorum communes tendons were in continuity without ruptures, both tendons were attenuated and stretched. The attenuated index extensor tendons were reconstructed either with shortening by plication or step-cut when the tendon damage was less severe or, in severely attenuated tendons, with tendon grafting (ipsilateral palmaris longus) or tendon transfer. Six months after the operation, the active extension of the index metacarpophalangeal joints had recovered well. CONCLUSIONS: Two cases of traumatic index extensor tendon attenuation were treated successfully by shortening the attenuated tendon in combination with tendon graft or transfer. We recommend WALANT (wide-awake local anesthesia and no tourniquet) in the reconstruction surgery of index extensor tendon attenuation to determine the appropriate amount of tendon shortening or optimal tension for tendon grafting or transfer. Intraoperative voluntary finger movement is essential, as it is otherwise difficult to judge the stretch length of intratendinous elongation and extent of traumatic intramuscular damage affecting tendon excursion.

Wireless Sensing of Lower Lip and Thumb-Index Finger 'Ramp-and-Hold' Isometric Force Dynamics in a Small Cohort of Unilateral MCA Stroke: Discussion of Preliminary Findings.

Automated wireless sensing of force dynamics during a visuomotor control task was used to rapidly assess residual motor function during finger pinch (right and left hand) and lower lip compression in a cohort of seven adult males with chronic, unilateral middle cerebral artery (MCA) stroke with infarct confirmed by anatomic magnetic resonance imaging (MRI). A matched cohort of 25 neurotypical adult males served as controls. Dependent variables were extracted from digitized records of 'ramp-and-hold' isometric contractions to target levels (0.25, 0.5, 1, and 2 Newtons) presented in a randomized block design; and included force reaction time, peak force, and dF/dtmax associated with force recruitment, and end-point accuracy and variability metrics during the contraction hold-phase (mean, SD, criterion percentage 'on-target'). Maximum voluntary contraction force (MVCF) was also assessed to establish the force operating range. Results based on linear mixed modeling (LMM, adjusted for age and handedness) revealed significant patterns of dissolution in fine force regulation among MCA stroke participants, especially for the contralesional thumb-index finger followed by the ipsilesional digits, and the lower lip. For example, the contralesional thumb-index finger manifest increased reaction time, and greater overshoot in peak force during recruitment compared to controls. Impaired force regulation among MCA stroke participants during the contraction hold-phase was associated with significant increases in force SD, and dramatic reduction in the ability to regulate force output within prescribed target force window (±5% of target). Impaired force regulation during contraction hold-phase was greatest in the contralesional hand muscle group, followed by significant dissolution in ipsilateral digits, with smaller effects found for lower lip. These changes in fine force dynamics were accompanied by large reductions in the MVCF with the LMM marginal means for contralesional and ipsilesional pinch forces at just 34.77% (15.93 N vs. 45.82 N) and 66.45% (27.23 N vs. 40.98 N) of control performance, respectively. Biomechanical measures of fine force and MVCF performance in adult stroke survivors provide valuable information on the profile of residual motor function which can help inform clinical treatment strategies and quantitatively monitor the efficacy of rehabilitation or neuroprotection strategies.

Anatomical basis and clinical application of the dorsal perforator flap based on the palmar artery in the first web.

PURPOSE: Soft-tissue defects of the thumb and index finger remain a challenge for plastic surgeons. Our purpose was to observe the morphological characteristics of the cutaneous vessels in the first web, to design a dorsal perforator flap based on the palmar artery in the first web and to propose its clinical application. METHODS: Thirty preserved hand specimens were dissected to observe the origin, course, branch and anastomosis of the dorsal perforators in the first web, and the dorsal perforator flap based on the palmar artery in the first web was designed. Clinically, seven cases of hand defects were reconstructed using this flap. RESULTS: The blood supply for the dorsum of the first web comprised the dorsal perforators from both the dorsal artery (the branch of the first dorsal metacarpal artery) and palmar artery (the radial palmar digital artery of the index finger and the ulnar palmar digital artery of the thumb). The first dorsal metacarpal artery constantly arose from the radial artery and was divided into the radial, ulnar and medial branches. The palmar artery sent out 1-2 perforators and formed a constant anastomosis with the medial branch of the first dorsal metacarpal artery to supply the dorsal skin of the first web. In clinical application, all the flaps survived completely without contracture of the first web or other complications and the donor regions all healed at the first stage. CONCLUSION: The dorsal perforator flap based on the palmar artery in the first web is useful to repair soft-tissue defects of the thumb, the proximal phalanx of the index finger and thenar region, leading to a satisfactory appearance and good functional and sensory recovery.

Effect of object and human-factor characteristics on the preference of thumb-index finger grasp type.

This work is to investigate the factors affecting the preference of human thumb-index finger grasping type. A multinomial logistic regression analysis shown that the object characteristics (equivalent diameter and shape) and human-factor characteristics (hand-used, finger-length sum and finger-length ratio) had significant contributions on the preference of thumb-index finger grasp type (p < 0.05) but the gender had not (p > 0.05). Subsequently, two mathematical equations were proposed for predicting the probability at which the precision-pinch and power-grasp were chosen for grasping an object. The probability at which the precision-pinch was chosen gradually decreased with the increase in the equivalent diameter of objects, but it is opposite for the power-grasp case. The shorter the finger-length sum, the more likely the participant was to select the power-grasp for grasping an object compared to the precision-pinch. The power-grasp was the most frequently chosen for the finger-length ratios of 1.0-1.25 and 1.75-2.0. Practitioner summary: This fruitful study gave explanation of the relationship between the object and human-factor characteristics and the preference of human thumb-index finger grasp type, which would be helpful to make intelligent grasping planning strategies for two-finger bionic mechanical hands.

A review of grasping as the movements of digits in space.

It is tempting to describe human reach-to-grasp movements in terms of two, more or less independent visuomotor channels, one relating hand transport to the object's location and the other relating grip aperture to the object's size. Our review of experimental work questions this framework for reasons that go beyond noting the dependence between the two channels. Both the lack of effect of size illusions on grip aperture and the finding that the variability in grip aperture does not depend on the object's size indicate that size information is not used to control grip aperture. An alternative is to describe grip formation as emerging from controlling the movements of the digits in space. Each digit's trajectory when grasping an object is remarkably similar to its trajectory when moving to tap the same position on its own. The similarity is also evident in the fast responses when the object is displaced. This review develops a new description of the speed-accuracy trade-off for multiple effectors that is applied to grasping. The most direct support for the digit-in-space framework is that prism-induced adaptation of each digit's tapping movements transfers to that digit's movements when grasping, leading to changes in grip aperture for adaptation in opposite directions for the two digits. We conclude that although grip aperture and hand transport are convenient variables to describe grasping, treating grasping as movements of the digits in space is a more suitable basis for understanding the neural control of grasping.

The impact of diabetic peripheral neuropathy on pinch proprioception.

This study aims to investigate the impact of type 2 diabetes (T2D) and diabetic peripheral neuropathy (DPN) on pinch proprioception and to establish the correlations with sensory impairments. We collected data from a total of 36 participants (healthy, n = 12; T2D without DPN, n = 11; and T2D + DPN, n = 13), all matched for age, 60 ± 6 years. Pinch proprioception was determined through 3 trials of attempts to actively reproduce 15° of pinch position without visual feedback. Target accuracy and precision was compared between groups using Kruskal-Wallis test. Sensation was tested through the two-point discrimination and Semmes-Weinstein monofilaments applied on the fingers. Sensory measures were correlated with pinch proprioception measures via Spearman's rank test. The T2D + DPN group showed significant decrements in accuracy and precision as compared to the T2D-only (p = 0.003 and p = 0.006, respectively) and the healthy groups (both p = 0.002); no significant differences were found between T2D-only and healthy. Spearman's rank showed moderate (r = 0.45-0.66, p < 0.001) correlations between pinch proprioception and sensory measures. Our results showed pinch proprioception disruption in people with T2D + DPN, but not in people with T2D-only. The awareness of pinch proprioceptive deficits is paramount for the safety of individuals with T2D and DPN. Moderate correlations between sensory impairments and pinch proprioceptive deficits suggest that not only superficial/discriminative sensation is implicated in proprioceptive decrements. Other mechanisms such as damage to muscle spindles or central nervous system associated with T2D + DPN warrant further investigations.

Index Finger Muscle Fatigue and Pistol Firing Failure.

OBJECTIVE: The aim of this study was to analyze finger strength and effects of muscle fatigue on the ability to shoot. BACKGROUND: The finger and hand muscles of soldiers are subject to high loads. For example, the trigger pull of military pistols can amount up to 58 N (≈6 kg) and could cause muscle fatigue in the trigger finger. For soldiers, however, maintaining the ability to shoot is essential for self-defense and survival. METHOD: The marksmanship training of 30 German soldiers (15 female) ages 18 to 40 years was evaluated. Three consecutive exercises with a total of 60 rounds were fired from target ranges of 5 and 10 m, equally using a single-action and double-action trigger mode. Maximum voluntary isometric contraction of the index finger (MVCIF) was measured before and after each of the three firing exercises. RESULTS: Shooting reduced MVCIF in female (88.2 ± 15.8 N to 67.3 ± 17.7 N, p < .001) and male soldiers (145.8 ± 21.7 N to 112.7 ± 26.6 N, p < .001). Of the 30 subjects, 23 were unable to shoot due to fatigue, including 15 of 15 female soldiers. The higher MVCIF was at rest, the less commonly (r = .73, p < .001) and the later (r = 0.82, p < .001) task failure occurred. Two intermissions of approximately 6 min did not suffice for a significant recovery. CONCLUSION: Excessive trigger pull weight causes muscle fatigue of the index finger and can ultimately lead to task failure during pistol marksmanship training. Short breaks are insufficient for the recovery of finger muscles. APPLICATION: This study presents a new perspective on ideal trigger pull weight, which should be carefully considered by manufacturers to allow repetitive firing and simultaneously ensure safe handling.

A new surgical technique for excision of orbital cavernous hemangioma: a 15-year experience.

PURPOSE: To present a new surgical technique for excision of orbital cavernous hemangiomas (CHs). METHODS: This retrospective case series study included patients with orbital CH who were operated from 2001 to 2016 at our referral center. Epidemiologic data, symptoms, signs, and images were reviewed from patients' files with at least one year of follow-up. Surgical results and complications were documented. We used the "index finger dissection" technique without grasping the tumor for release of adhesions and its removal. RESULTS: We included 60 patients with orbital CH consisting of 36 (60%) female and 24 (40%) male patients with mean age of 40 ± 12.1 (range 9-66) years. The main complaint was proptosis with average size of 5.3 ± 2 millimeters. The surgical approach was lateral orbitotomy in 49 (81.7%) patients, medial transcutaneous in seven (11.7%) patients, inferior transconjunctival in three (5%) patients, and simultaneous lateral and medial orbitotomy in one (1.6%) patient. All tumors were removed intact; complications included ptosis in one subject, lower lid retraction in one case, and diplopia in two patients, all of which improved before 2 months. No optic nerve damage occurred. CONCLUSION: The "index finger dissection" technique without grasping the tumor for excision of orbital CH, via any external approach to the tumor, is a safe technique with minimal complications.

Pinch aperture proprioception: reliability and feasibility study.

[Purpose] To establish the reliability and feasibility of a novel pinch aperture device to measure proprioceptive joint position sense. [Subjects and Methods] Reliability of the pinch aperture device was assessed in 21 healthy subjects. Following familiarization with a 15° target position of the index finger and thumb, subjects performed 5 trials in which they attempted to actively reproduce the target position without visual feedback. This procedure was repeated at a testing session on a separate date, and the between-session intraclass correlation coefficient (ICC) was calculated. In addition, extensor tendon vibration was applied to 19 healthy subjects, and paired t-tests were conducted to compare performance under vibration and no-vibration conditions. Pinch aperture proprioception was also assessed in two individuals with known diabetic neuropathy. [Results] The pinch aperture device demonstrated excellent reliability in healthy subjects (ICC 0.88, 95% confidence interval 0.70-0.95). Tendon vibration disrupted pinch aperture proprioception, causing subjects to undershoot the target position (18.1 ± 2.6° vs. 14.8° ± 0.76, p<0.001). This tendency to undershoot the target position was also noted in individuals with diabetic neuropathy. [Conclusion] This study describes a reliable, feasible, and functional means of measuring finger proprioception. Further research should investigate the assessment and implications of pinch aperture proprioception in neurological and orthopedic populations.

Anterior interosseous nerve palsy mimicking rupture of the index flexor digitorum profundus after volar locking plate fixation of a distal radius fracture.

We describe the case of a patient with distal radius fracture who became unable to flex the distal interphalangeal joint of the index finger after internal fixation using a volar locking plate. There was palpable crepitus with active thumb motion, and wrist radiographs showed prominence of the volar plate at the watershed line. Therefore, our initial diagnosis was plate-induced closed rupture of the flexor digitorum profundus tendon of the index finger. However, upon surgical removal of the plate, no tendon rupture was found. Magnetic resonance imaging after plate removal showed diffuse increased signal intensity in the index flexor digitorum profundus on T2-weighted fat-suppressed images, which indicated muscle denervation. Based on the above findings, we changed the diagnosis to anterior interosseous nerve palsy with isolated paralysis of the flexor digitorum profundus of the index finger. Finger flexion disability following volar plate fixation of distal radius fracture should always be investigated carefully..

Increased Force Variability Is Associated with Altered Modulation of the Motorneuron Pool Activity in Autism Spectrum Disorder (ASD).

Force control deficits have been repeatedly documented in autism spectrum disorder (ASD). They are associated with worse social and daily living skill impairments in patients suggesting that developing a more mechanistic understanding of the central and peripheral processes that cause them may help guide the development of treatments that improve multiple outcomes in ASD. The neuromuscular mechanisms underlying force control deficits are not yet understood. Seventeen individuals with ASD and 14 matched healthy controls completed an isometric index finger abduction test at 60% of their maximum voluntary contraction (MVC) during recording of the first dorsal interosseous (FDI) muscle to determine the neuromuscular processes associated with sustained force variability. Central modulation of the motorneuron pool activation of the FDI muscle was evaluated at delta (0-4 Hz), alpha (4-10 Hz), beta (10-35 Hz) and gamma (35-60 Hz) frequency bands. ASD patients showed greater force variability than controls when attempting to maintain a constant force. Relative to controls, patients also showed increased central modulation of the motorneuron pool at beta and gamma bands. For controls, reduced force variability was associated with reduced delta frequency modulation of the motorneuron pool activity of the FDI muscle and increased modulation at beta and gamma bands. In contrast, delta, beta, and gamma frequency oscillations were not associated with force variability in ASD. These findings suggest that alterations of central mechanisms that control motorneuron pool firing may underlie the common and often impairing symptoms of ASD.

Reoperation After Combined Injury of the Index Finger: Repair Versus Immediate Amputation.

PURPOSE: To identify factors associated with unplanned reoperation of severely injured index fingers and to address the number of amputations after initial repair. METHODS: In this retrospective study, we included all patients older than 18 years of age who had repair or immediate amputation for combined index finger injury at 2 level I trauma centers and 1 community hospital tied to a level I trauma center between January 2004 and February 2014. Twelve patients were excluded because of inadequate follow-up. Bivariate and multivariable analyses sought factors associated with unplanned reoperation after repair and immediate amputation. RESULTS: Among 114 patients with combined injury, 75 were treated with repair and 39 with immediate amputation. A total of 41 patients had an unplanned reoperation, 33 after repair (44%) and 8 after immediate amputation (21%). In multivariable analysis, patients who had a reoperation for fingers other than the index finger were at risk for unplanned reoperation after repair. Women were more likely to have an unplanned reoperation than men, and patients who had a ray amputation were at risk for unplanned reoperation after immediate amputation. Six patients (18%) had amputation after initial repair. CONCLUSIONS: Surgeons may counsel patients that they are twice as likely to have an unplanned reoperation after a repair for combined injury of the index finger compared with an immediate amputation. Unplanned reoperations were more common among patients with injuries involving multiple fingers. Effective shared decision making is particularly important in this setting given that 1 in 5 repaired index fingers were eventually amputated. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Grasp and index finger reach zone during one-handed smartphone rear interaction: effects of task type, phone width and hand length.

Recently, some smartphones have introduced index finger interaction functions on the rear surface. The current study investigated the effects of task type, phone width, and hand length on grasp, index finger reach zone, discomfort, and muscle activation during such interaction. We considered five interaction tasks (neutral, comfortable, maximum, vertical, and horizontal strokes), two device widths (60 and 90 mm) and three hand lengths. Horizontal (vertical) strokes deviated from the horizontal axis in the range from -10.8° to -13.5° (81.6-88.4°). Maximum strokes appeared to be excessive as these caused 43.8% greater discomfort than did neutral strokes. The 90-mm width also appeared to be excessive as it resulted in 12.3% increased discomfort relative to the 60-mm width. The small-hand group reported 11.9-18.2% higher discomfort ratings, and the percent maximum voluntary exertion of their flexor digitorum superficialis muscle, pertaining to index finger flexion, was also 6.4% higher. These findings should be considered to make smartphone rear interaction more comfortable. Practitioner Summary: Among neutral, comfortable, maximum, horizontal, and vertical index finger strokes on smartphone rear surfaces, maximum vs. neutral strokes caused 43.8% greater discomfort. Horizontal (vertical) strokes deviated from the horizontal (vertical) axis. Discomfort increased by 12.3% with 90-mm- vs. 60-mm-wide devices. Rear interaction regions of five commercialised smartphones should be lowered 20 to 30 mm for more comfortable rear interaction.

Penile length-somatometric parameters relationship in healthy Egyptian men.

This study aimed to assess the penile length-somatometric parameters relationship in healthy Egyptian men. Two thousand physically normal men (22-40 years) were subjected to measurement of stretched penile length, glans penis, testis size, index finger, weight, height, span, body mass index (BMI), waist circumference, hip circumference and waist/hip ratio. The mean stretched penile length of the studied subjects was 13.84 ± 1.35 cm (range 12-19 cm), and the mean glans penis length was 2.6 ± 0.4 cm (range 1.7-3.8 cm). Penile length demonstrated positive significant correlation with glans penis length, index finger length, BMI and significant negative correlation with waist/hip ratio. On the other hand, penile length demonstrated nonsignificant correlation with age, weight, height, waist circumference, span or testicular size. It is concluded that the penile length-somatometric parameters relationship in healthy Egyptian men is mostly related to glans penis and index finger lengths.

Prosthetic Arthroplasty Versus Arthrodesis for Osteoarthritis and Posttraumatic Arthritis of the Index Finger Proximal Interphalangeal Joint.

PURPOSE: To compare outcomes of prosthetic arthroplasty versus arthrodesis to treat index finger proximal interphalangeal (PIP) joint arthritis. METHODS: Patients with osteoarthritis or posttraumatic arthritis of index finger PIP joints were evaluated. Digit range of motion, grip and pinch strength, patient-rated pain and satisfaction scores, Michigan Hand Questionnaire scores, and complications were recorded. RESULTS: A total of 79 finger PIP joints were followed for a median of 67 months overall (72 months for arthroplasty and 8 months for the arthrodesis group). Sixty-five were treated with arthroplasty and 14 with arthrodesis. Patients undergoing arthroplasty experienced no significant postoperative change in PIP joint range of motion whereas all preoperative PIP joint motion was eliminated after arthrodesis. Patients undergoing arthroplasty experienced significant postoperative improvement in opposition pinch. In contrast, patients undergoing arthrodesis experienced significant improvement in both opposition and apposition pinch. There were no differences in pain relief, satisfaction, or Michigan Hand Questionnaire scores between treatment groups. Patients undergoing arthroplasty had a significantly greater mean number of complications per year and mean number of complications in the first year postoperatively. There was a 4.3 times increased risk of complication in patients undergoing arthroplasty versus arthrodesis, and Kaplan-Meier analysis revealed a shorter time to first complication among patients undergoing arthroplasty. CONCLUSIONS: The decision for prosthetic arthroplasty versus arthrodesis in the index finger of patients with osteoarthritis or posttraumatic arthritis must be made with patient goals in mind and in light of greater risk of complications associated with arthroplasty.