The contribution of the intrinsic muscles to grip and pinch strength

Distal nerve transfers for peripheral nerve injuries: indications and outcomes

Distal nerve transfer is a refined surgical technique involving the redirection of healthy sacrificable nerves from one part of the body to reinstate function in another area afflicted by paralysis or injury. This approach is particularly valuable when the original nerves are extensively damaged and standard repair methods, such as direct suturing or grafting, may be insufficient. As the nerve coaptation is close to the recipient muscles or skin, distal nerve transfers reduce the time to reinnervation. The harvesting of nerves for transfer should usually result in minimal or no donor morbidity, as any anticipated loss of function is compensated for by adjacent muscles or overlapping cutaneous territory. Recent years have witnessed notable progress in nerve transfer procedures, markedly enhancing the outcomes of upper limb reconstruction for conditions encompassing peripheral nerve, brachial plexus and spinal cord injuries.

Applied Force Alters Sensorineural and Peripheral Vascular Function in a Rat Model of Hand-Arm Vibration Syndrome

OBJECTIVE

This study described the effects of applied force (grip) on vascular and sensorineural function in an animal model of hand-arm vibration syndrome (HAVS).

METHODS

Rat tails were exposed to 0, 2, or 4 N of applied force 4 hr/d for 10 days. Blood flow and sensitivity to transcutaneous electrical stimulation and pressure were measured.

RESULTS

Applied force increased blood flow but reduced measures of arterial plasticity. Animals exposed to force tended to be more sensitive to 250-Hz electrical stimulation and pressure applied to the tail.

CONCLUSIONS

Effects of applied force on blood flow and sensation are different than those of vibration. Studies examining co-exposures to force and vibration will provide data that can be used to determine how these factors affect risk of workers developing vascular and sensorineural dysfunction (ie, HAVS).

Force loss and distribution of load in the hands of patients with cubital tunnel syndrome

Manugraphy with three different cylinder sizes was used to quantify the contribution of fingers, thumb and palm to grip force in patients with unilateral cubital tunnel syndrome. Forces in the affected and contralateral hands differed by up to 29%. Although grip force is usually maximal when gripping small handles, ulnar nerve palsy resulted in similar absolute grip forces using the 100-mm and 200-mm cylinders. The contact area between the affected hand and the cylinders was reduced by 5%-9%. We noted a high correlation between the contact area and grip force, visible atrophy and permanently impaired sensibility. The load distribution differed significantly between both hands for all cylinder sizes. When gripping large objects, the main functional impairment in cubital tunnel syndrome is weakness in positioning and stabilizing the thumb. Weak intrinsic finger muscles are responsible for loss of force when gripping small objects. Level of evidence: III.

Accuracy of Force Generation and Preparatory Prefrontal Oxygenation in Ballistic Hand Power and Precision Grips

It remains unclear whether accurate motor performance and cortical activation differ among grasping forms across several force levels. In the present study, a ballistic target force matching task (20%, 40%, 60%, and 80% of maximum voluntary force) with power grip, side pinch, and pulp pinch was utilized to explore the accuracy of the forces generated as well as the muscular activity of intrinsic and extrinsic hand muscles. By using near-infrared spectroscopy, we also examined bilateral dorsolateral prefrontal cortex (DLPFC) activation during the preparatory phase (initial 10 s) of the task. The accuracy of the power grip and pulp pinch was relatively higher than that of the side pinch, and the electromyographic activity of intrinsic hand muscles exhibited a similar trend for power grip and side pinch, while the opposite muscle recruitment pattern was observed for pulp pinch. The increment of DLPFC oxygenation across force levels differed among grasping forms, with greater activity at relatively higher levels in the power grip and side pinch, and at relatively lower levels in the pulp pinch. Taken together, the differential contribution of the DLPFC may be responsible for force generation depending on different grasping forms and force levels.

Ulnar-Sided Upper Extremity Traumatic Wounds: What Should We Expect to Find?

Background: Upper limb traumatic injuries have a significant impact on social and professional life; however, there is still a paucity of studies focusing on the injuries of the ulnar border of the forearm, wrist and hand. Methods: We designed a retrospective single-blinded study, including all patients with deep traumatic wounds affecting the ulnar side of the forearm, wrist or hand, that received surgical treatment from 2006 until 2016. A characterisation of the sample, assessment of concomitant injuries and clinical outcomes, as well as neurological and functional evaluation were performed. Results: We obtained a sample of 61 patients, 69% with injuries affecting the wrist and 90% of patients with a neurological lesion, most frequently of the ulnar nerve lesion (UNL). Concomitant injuries included tendinous lesions, more frequently of the flexor carpi ulnaris (64%) and fractures (13%). And 39% of patients presented an ulnar artery lesion, without significant differences in outcomes regarding the completion of arteriorrhaphy or not. At the end of the 8.6 years follow-up, 34% of patients had no deficits; however, patients with UNL showed worse functional scores and greater risk of sequelae. Besides motor function compromise, sensory deficits were also associated with worst functional outcomes. Conclusions: The UNL subgroup showed important impairment of the first ray, probably related to the level of UNL. Furthermore, besides the implications of the motor sequelae, sensory deficits were also associated with worst functional scores. Due to the high percentage of neurovascular and tendinous lesions in ulnar-sided upper extremity wounds, the authors recommend surgical exploration of these lesions. Level of Evidence: Level IV (Therapeutic).

Inhibitory Effects of Prolonged Focal Muscle Vibration on Maximal Grip Strength and Muscle Activity of Wrist and Extrinsic Finger Flexor Muscles

Objective

The objective of this study was to identify effective stimulus time by quantifying the inhibitory effects of focal muscle vibration (FMV) on maximal grip strength and muscle activities of the wrist and extrinsic finger flexors.

Methods

A randomized repeated-measures design was used in this study. A total of 22 healthy volunteers (mean age, 20.9 years) participated. An FMV of 86 Hz was applied to the anterior surface of the distal forearm under the following 3 conditions: no FMV (control), 5-minute FMV, and 10-minute FMV. Maximal grip strength was measured before and after FMV. The muscle activities of the flexor digitorum superficialis, flexor digitorum profundus (FDP), and flexor carpi ulnaris were simultaneously recorded using surface electromyography. Discomfort and complications following FMV were also assessed.

Results

Compared with the control group, a significant decrease in muscle activity was observed in both the flexor digitorum superficialis and flexor carpi ulnaris after 5 and 10 minutes of FMV. In contrast, there was no significant decrease in the maximal grip strength or FDP muscle activity after either FMV condition. The discomfort was significantly higher immediately after both FMV conditions than in the control group, but it decreased 15 minutes after FMV, indicating no significant difference among the 3 conditions. Redness and/or swelling were observed in 13.6% and 36.3% of the participants after 5 and 10 minutes of FMV, respectively.

Conclusion

Five-minute FMV to the distal forearm could be a useful therapeutic method with few complications. However, the FMV in this area alone was not sufficient to suppress the muscle activity of the FDP located in the deep layer.

Tendon Transfer versus Nerve Transfer for the Reconstruction of Key Pinch and Grip Strength in Isolated High Traumatic Injuries of the Ulnar Nerve: A Systematic Review

Background: Primary repair for traumatic injuries to the ulnar nerve alone does not always restore satisfactory hand function, particularly in injuries above the elbow where the long distances for regeneration limit motor reinnervation. Reductions in key pinch and grip strength are some of the main complaints. Tendon transfers have traditionally been used to improve key pinch and grip strength as a late salvage where primary nerve regeneration has run its course. Nerve transfers have been proposed as an alternative procedure and may be offered early to augment recovery, lengthen the window for reinnervation or provide motor reinnervation where the results of nerve repair are expected to be poor. This review sought to identify whether one type of procedure was superior to the other for reconstructing key pinch and grip strength. Methods: Medline, Embase and Cochrane Library were searched to identify articles that concerned nerve or tendon transfer following isolated traumatic injury to the ulnar nerve. Articles were excluded if patients had polytrauma or degenerative diseases of the peripheral nerves. Results: A total of 179 articles were screened for inclusion. And 35 full-text articles were read and assessed for eligibility, of which seven articles were eligible. Following citation search, two additional articles were included. Five tendon transfer articles and four nerve transfer articles were included. Key pinch and grip strength outcomes for both procedures were roughly similar, though tendon transfers carried a much higher risk of complications. Conclusions: Based on the key pinch and grip strength outcomes, tendon transfer and nerve transfer restore a similar degree of function following traumatic ulnar injury. Reported nerve transfer outcomes for grip strength were slightly better. Return to useful function was faster following tendon transfers. Preoperative data and more patient-reported outcome measures should be recorded in future studies to provide more context for each procedure type. Level of Evidence: Level III (Therapeutic).

Test-retest Reliability and Precision of the Rotterdam Intrinsic Hand Myometer

PURPOSE

The purpose of this study was to determine the test-retest reliability and precision of Rotterdam Intrinsic Hand Myometer (RIHM) in healthy adults.

METHODS

Twenty-nine participants originally recruited via convenience sampling at a Midwestern state fair returned approximately 8 days later for retest. An average of three trials for each of the five intrinsic hand strength measurements were collected using the same technique that was used during initial testing. Test-retest reliability was assessed using the intraclass correlation coefficient or ICC(2,3) and precision was evaluated using the standard error of measurement (SEM), and the minimal detectable change (MDC90)/MDC%.

RESULTS

Across all measures of intrinsic strength, the RIHM and its standardized procedures had excellent test-retest reliability. Index finger metacarpophalangeal flexion demonstrated the lowest reliability, and right small finger abduction, left thumb carpometacarpal abduction, and index finger metacarpophalangeal abduction tests had the highest reliability. Precision, as evidenced by SEM and MDC values, was excellent for tests of left index and bilateral small finger abduction strength and acceptable for all other measurements.

CONCLUSIONS

Test-retest reliability and precision of RIHM across all measurements was excellent.

CLINICAL RELEVANCE

These findings indicate that RIHM is a reliable and precise tool in measuring intrinsic strength of hands of healthy adults, although further research is needed in clinical populations.

Normal Values of the Second Interosseous Pinch: A Measurement of Pure Ulnar-Innervated Intrinsic Muscles of the Hand

PURPOSE

The second palmar interosseous muscle is innervated solely by the ulnar nerve, and second palmar interosseous pinch (2IP) strength may be a good indicator of ulnar nerve motor function. The goal of this study was to describe the 2IP test and establish its normative values, stratified by age, sex, and dominance.

METHODS

Volunteers were recruited to participate in this study at various community locations. Patients over the age of 18 years were eligible for this study. Demographic information on all subjects was collected. The volunteers were asked to pinch a hydraulic pinch gauge between the index and middle finger proximal phalanges with the proximal and distal interphalangeal joints flexed and without recruiting the thumb. Three 2IP measurements were taken for each hand. Descriptive statistics and analysis of covariance were performed to determine the effect of age, sex, dominance, and side on 2IP. We analyzed the 2IP strength using the 2IP test across 3 trials to determine whether it was affected by repeated testing.

RESULTS

Two hundred thirty-eight patients met the inclusion criteria (45 ± 21 years, 55% women, 87% right-hand dominant). There was no statistically significant difference between dominant and nondominant hands or among the 3 trials. There was a statistically significant correlation between age and 2IP strength ranging between 0.32 and 0.44 kg. Age and sex showed a statistically significant association with 2IP strength, with patients of older age and women having weaker 2IP.

CONCLUSIONS

We determined normative values for 2IP strength using a sample from a normal population. More studies are needed to validate these results.

CLINICAL RELEVANCE

Second interosseous pinch strength may be a useful tool to assess ulnar nerve function.

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

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

Dynamic Rather than Static Procedures in Correcting Claw Deformities Due to Ulnar Nerve Palsy

The theoretic disadvantage of dynamic tendon transfers is the perception that they are "more complex" than static procedures. The latter may provide a simple solution to claw deformity in a subset of patients; however, they completely disregard the disability associated with loss of the intrinsic musculature. Dynamic procedures reconstruct in part the deficient intrinsic forces and are thus capable of correcting the deformity and some disabilities associated with ulnar nerve palsy. In our practice, we have consistently achieved reasonable correction of claw deformity and improvement in tendon synchrony and grip strength with a modified Stiles-Bunnell, flexor digitorum superficialis tendon transfer.

Greater Cortical Activation and Motor Recovery Following Mirror Therapy Immediately after Peripheral Nerve Repair of the Forearm

Cortical reorganization occurs immediately after peripheral nerve injury, and early sensorimotor training is suggested during nerve regeneration. The effect of mirror therapy and classical sensory relearning on cortical activation immediately after peripheral nerve repair of the forearm is unknown. Six participants were randomly assigned to the mirror-therapy group or the sensory-relearning group. Sensorimotor training was conducted in a mirror box for 12 weeks. The mirror-therapy group used mirror reflection of the unaffected hand in order to train the affected hand, and the sensory-relearning group trained without mirror reflection. Semmes-Weinstein Monofilaments (SWM) test, static 2-point discrimination test (S-2PD), grip strength, and the Disabilities of the Arm, Shoulder and Hand (DASH) scores were measured at baseline, the end of the intervention (T1), and 3 months after the intervention (T2). Finger and manual dexterity were measured at T1 and T2, and a functional MRI (fMRI) was conducted at T1. All participants showed improvement in the SWM, S-2PD tests, upper extremity function, and grip strength after the intervention at T1, except for the participant who injured both the median and ulnar nerves in the sensory-relearning group. In addition, the mirror-therapy group had better outcomes in finger dexterity and manual dexterity, and fMRIs showed greater activation in the multimodal association cortices and ipsilateral brain areas during motor tasks. This study provides evidence-based results confirming the benefits of early sensorimotor relearning for cortical activation in peripheral nerve injury of the forearm and different neuroplasticity patterns between mirror therapy and classical sensor relearning.

A Detailed Comparison of Preoperative Complaints in Severe Carpal Tunnel Syndrome versus Recurrent Carpal Tunnel Syndrome Using the Boston Carpal Tunnel Questionnaire

Background: The Boston Carpal Tunnel Questionnaire (BCTQ) has a symptom severity scale (SSS) with 11 questions and a functional status scale (FSS) with 8 questions. The final score for each scale is the sum divided by the number of questions and ranges between 1 and 5. A score of 1 indicates they have no complaints and 5 indicates high severity and functional loss. Unfortunately, this single digit score does not permit a detailed analysis of the symptoms and functional status. The aim of this study is to conduct an in-depth comparison of preoperative complaints using the BCTQ between patients with severe carpal tunnel syndrome (SCTS) and recurrent carpal tunnel syndrome (RCTS). Methods: This is a retrospective cohort study on the preoperative status of 37 patients with SCTS and 18 patients with RCTS using the BCTQ. The questions in the SSS and FSS were classified into four groups based on the responses of patients, namely a low complaint (LC) (1-1.99), moderate complaint (MC) (2-2.99), high complaint (HC) (3-3.99), and severe complaint (SC) (4-5) groups. The patients in the SCTS and RCTS groups were compared to find differences in age, gender, hand dominance, and responses to questions in the SSS and FSS. Results: The age of patients in the SCTS group (76.06 years) was significantly higher compared to the RCTS group (51.11 years). There was no significant difference between the two groups with regard to gender or hand dominance. The top question with SC or HC response in the SCTS group was problems in grasping small objects (SSS) and fastening buttons (FSS) and in the RCTS group was tingling in the hand (SSS) and difficulty with opening a jar (FSS). Conclusions: An in-depth analysis of the BCTQ allowed us to compare and understand differences in symptoms and function between patients with SCTS and RCTS. Level of Evidence: Level III (Therapeutic).

Subperiosteal Ulnar Nerve Entrapment at the Wrist

Ulnar nerve entrapment at the wrist can cause debilitating sensory, motor, or sensory and motor deficits in the hand. The sources of compression have been well documented, with ganglions, lipomas, and trauma being common etiological factors. We treated a professional sculptor with intrinsic pain and weakness in her dominant hand because of compression caused by the subperiosteal course of her deep motor branch of the ulnar nerve. The nerve traversed on the radial side of the hook of the hamate and descended into the floor of the palm in the carpal tunnel through the transverse carpal ligament. We present this previously unreported anatomical anomaly and the subsequent operative treatment. Knowledge of this anatomical variation is paramount in avoiding injury to the ulnar nerve when operating the Guyon canal or carpal tunnel, among other hand and wrist surgeries.

Grip Strength Measurement for Outcome Assessment in Common Hand Surgeries

Grip strength has been used to evaluate the upper extremity functional status and clinical outcomes following upper extremity trauma or surgery. Understanding general recovery patterns of grip strengthening can be helpful in assessing the patients’ recovery status and in assisting in preoperative consultations regarding expectations for recovery. We summarize related studies on grip strength measurement and recovery patterns in common hand conditions, including carpal tunnel syndrome, cubital tunnel syndrome, triangular fibrocartilage complex injury, and distal radius fractures.

Predicting metacarpal length using paired ratios with bilateral X-ray films

Introduction:

When the metacarpal bones sustain severe osseous injury requiring reconstruction, functional recovery relies on the precise distribution of tension throughout full range of motion. While the small scale of hand structures compounds the effects of altering normal anatomy, literature lacks consensus recommendations for the acceptable degree of length alteration and/or appropriate methods of length estimation in reconstructive procedures. Length asymmetry has been reported in human metacarpal bones; however, studies assessing this phenomenon in living subjects with attention to functional implications or length prediction are lacking.

Methods:

Hand X-rays were obtained for 34 patients aged 25–80 without history of metacarpal trauma, joint degeneration, or pathologic bone metabolism. A scaled bivariate model predicted metacarpal length using an ipsilateral paired metacarpal and matching contralateral ratio: Estimate_Dx_R = Median_Dy_R * (Median_Dx_L/Median_Dy_L). A second set of predictions used the contralateral metacarpal as a control. Pearson correlation coefficients, paired t-tests, and chi-square tests evaluated the symmetry between bilateral metacarpal lengths and paired metacarpal ratios as well as the accuracy of each predictive method.

Results:

The contralateral control and target metacarpal differed significantly in digits 1, 2, 3, and 5. No significant difference in matched metacarpal ratios of the right and left hands was found. For all digits except 5D, bivariate model predictions generated were more strongly correlated with actual target length. Chi-square tests did not detect a significant difference in predictive value of the two models.

Conclusion:

The scaled bivariate model we describe may be useful and economic in generating accurate length estimates of metacarpals for reconstructive procedures.

Outcomes and Complications of Tendon Transfers to Address Pinch and Grasp Weakness: A Systematic Review of the Operative Management of Ulnar Nerve Paralysis

BACKGROUND

Patients with ulnar nerve paralysis note difficulties performing activities of daily living because of weakness of pinch and altered grasp mechanism. This review investigates outcomes of tendon transfers for ulnar nerve paralysis to assist in shared decision-making with patients during preoperative counseling and to inform operative choices.

METHODS

A systematic review was conducted to identify studies reporting outcomes following tendon transfer for ulnar nerve palsy. Studies were screened according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, and inclusion and exclusion criteria were applied. Primary outcome measures included postoperative pinch strength and mechanism of grasp.

RESULTS

A total of 26 studies (687 patients) met criteria for inclusion. After pooled analysis, the flexor digitorum superficialis lasso procedure yielded the highest rate of complete correction of claw deformity (60.6 percent), followed by flexor digitorum superficialis four-tail operation (31.4 percent). The extensor carpi radialis longus four-tail operation yielded the greatest improvement in grip strength (3.8 kg). The extensor carpi radialis brevis four-tail operation resulted in the best open hand assessment and mechanism of closing scores; however, these studies did not objectively evaluate grip strength. The greatest increase in pinch strength was following tendon transfer to adductor pollicis alone.

CONCLUSIONS

Despite the heterogeneous data, if the primary goal is improvement in the appearance of claw deformity, the evidence supports flexor digitorum superficialis lasso transfer. However, if the primary concern is grip strength, the data favor extensor carpi radialis longus four-tail transfer. When pinch strength is functionally limiting, adductorplasty alone is most effective. These data will assist providers in appropriately informing patients of common risks and complications and setting realistic expectations following tendon transfer procedures.

"Million dollar nerve" magnetic resonance neurography: first normal and pathological findings

OBJECTIVES

To evaluate prospectively the feasibility of magnetic resonance neurography (MRN) in identifying the anatomical characteristics of thenar muscular branch (TMB) of the median nerve, also known as the "million dollar nerve," in patients and controls.

METHODS

Thirteen patients affected by carpal tunnel syndrome (CTS) and four healthy controls had their hands scanned on a 3-T MR imaging scanner for TMB visualization. Median nerve anatomical variations were classified into four groups according to Poisel's classification system modified by Lanz. TMB signal intensity and diameter were assessed for the diagnosis of neuropathy.

RESULTS

TMB was successfully identified in all patients and subjects by using MRN. The most suitable pulse sequences to identify and measure nerve diameter were 3D DW-PSIF and T2-FS-TSE. The axial oblique and sagittal oblique planes are complementary in demonstrating its entire course. TMB had mostly an extraligamentous course with radial side origin (93.8%, each). All patients experienced increased T2 signal intensity (p < 0.001) and thickened nerves. Mean TMB diameters were 1.27 ± 0.21 mm (range, 1.02-1.74 mm) and 0.87 ± 0.16 mm (0.73-1.08 mm) (p = 0.008) in the patient and control groups, respectively.

CONCLUSION

MRN is a reliable imaging technique for identification and anatomical characterization of TMB in patients affected by CTS. This innovative imaging workup may therefore be included in the preoperative evaluation of patients scheduled for carpal tunnel release, especially in CTS with TMB involvement or even in isolated TMB neuropathy.

KEY POINTS

• Magnetic resonance neurography allows precise visualization of the thenar muscular branch of the median nerve. • Thenar muscular branch anatomical variations can be correctly identified. • Preoperative scanning can contribute to reducing the risk of iatrogenic injuries during carpal tunnel release, especially in carpal tunnel syndrome with thenar muscular branch involvement or even in isolated thenar muscular branch neuropathy.

Baseball Injuries of the Hand and Wrist

Injuries of the hand and wrist are common in baseball. Because of the unique motions and loads encountered in this sport, physicians treating baseball players may encounter hand and wrist injuries ranging from common to rare. An understanding of these baseball-related injuries must include their pathoanatomy, diagnosis, and treatment options. This knowledge is critical for the general orthopaedic surgeon treating baseball players to allow for timely and appropriate treatment. This article reviews the pathophysiology, diagnosis, and treatment of baseball-related hand and wrist injuries, with a target audience of general orthopeadic surgeons.

Fascicle-Specific Targeting of Longitudinal Intrafascicular Electrodes for Motor and Sensory Restoration in Upper-Limb Amputees

Multichannel longitudinal intrafascicular electrode (LIFE) interfaces provide optimized balance of invasiveness and stability for chronic sensory stimulation and motor recording/decoding of peripheral nerve signals. Using a fascicle-specific targeting (FAST)-LIFE approach, where electrodes are individually placed within discrete sensory- and motor-related fascicular subdivisions of the residual ulnar and/or median nerves in an amputated upper limb, FAST-LIFE interfacing can provide discernment of motor intent for individual digit control of a robotic hand, and restoration of touch- and movement-related sensory feedback. The authors describe their findings from clinical studies performed with 6 human amputee trials using FAST-LIFE interfacing of the residual upper limb.

Correction of ulnar claw hand and Wartenberg's sign

Ulnar claw hand usually occurs when the ulnar nerve is damaged distally. Claw hand deformity is characterized by metacarpophalangeal hyperextension and interphalangeal flexion, making it impossible to oppose the fingers and thumb. Bouvier's test is used to guide the procedure. Palliative surgery requires prior preparation of paralytic hands. In case of a positive Bouvier's test, Zancolli's lasso technique is preferred because of its effectiveness. Capsuloplasty with anteroposterior transosseous fixation is used if the bone is strong enough and when flexor digitorum profondus muscle is inactive and does not allow flexor digitorum superficialis tendon transfer. In case of a negative Bouvier's test with interphalangeal extension deficit of 45 degrees of less, direct interossei muscle restoration techniques by active transfers are performed. If the interphalangeal extension deficit is more than 45 degrees, proximal interphalangeal arthrodesis is indicated. Wartenberg first described actively irreducible abduction of the little finger. Wartenberg's sign is seen when ulnar paralysis occurs, and during ulnar nerve regeneration. Treatment of isolated Wartenberg's sign consists of re-routing the extensor digiti minimi. Among the other techniques, Belmahi's "tie lasso" is preferred when flexible claw hand is associated with Wartenberg's sign.

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.

Computed Tomography Evaluation of Forearm and Hand Muscles in Patients With Distal Radius Fracture

INTRODUCTION

Computed tomography (CT) can be used to assess bone status with measurement of Hounsfield unit (HU). The objective of this study was to evaluate whether HU of muscle might be associated with parameters of bone and muscle status.

METHODS

We reviewed 71 women aged over 50 yr of age who had distal radius fracture and underwent CT evaluation of affected wrist. We assessed HUs of forearm flexor muscles (flexor digitorum superficialis) and thenar muscles and bone HUs at the capitate and the ulnar head. Other parameters included femur neck and lumbar bone mineral density (BMD), upper extremity lean mass, hand grip strength, and muscle fiber cross-sectional area. We performed correlation analyses to determine associations between variables.

RESULTS

Thenar and forearm muscle HUs were significantly correlated with each other, but not with other parameters. HUs of the capitate and ulnar head were positively correlated with femur neck and lumbar BMDs and inversely correlated with age. Ulnar head HU was positively correlated hand grip strength.

CONCLUSIONS

HUs of forearm and thenar muscles did not show significant correlations with bone or muscle parameters, although bone HUs correlated well with bone mineral densities. These results support the opportunistic use of CT for evaluating bone fragility. Clinical usefulness of muscle HU measurement needs further studies.

Relationship between ultrasonographic hand muscle thickness measurements and muscle strength following median or ulnar nerve reconstruction

INTRODUCTION

The aim of this study was to assess the relationship between ultrasonographic hand muscle thickness measurements and hand muscle strength in patients who underwent median or ulnar nerve reconstruction.

METHODS

In this prospective, cross-sectional study, intrinsic hand muscle thicknesses were measured using ultrasound with a 4- to 13-MHz linear-array probe. Measurements of hand strength were performed using a dynamometer and a pinchmeter.

RESULTS

In the median nerve group (n = 11), a moderate correlation (r = 0.694; P = .018) was observed between lateral pinch strength and transverse thenar thickness. In the ulnar nerve group (n = 11), longitudinal thenar thickness below the flexor pollicis longus tendon was moderate to highly correlated with pinch and handgrip strengths (r = 0.726-0.893; P < .05); whole transverse thenar thickness was moderate to highly correlated with pinch strengths (r = 0.724-0.836; P < .05).

DISCUSSION

Sonographic measurements of intrinsic hand muscle thickness may be a useful tool for the assessment and follow-up of patients with median or ulnar nerve injury.

[Selective nerve transfers for thenar branch reconstruction]

OPERATIVE

Reconstruction of thump opposition with selective nerve transfer of the motor branch of the abductor digiti minimi muscle (ADM) to the thenar motor branch.

INDICATIONS

Injury of the median nerve or thenar motor branch and resulting loss of thumb opposition.

CONTRAINDICATIONS

Combined median and ulnar nerve injuries or brachial plexus lesions of C8-Th1, or a time interval >12 months since denervation of the thenar branch.

SURGICAL TECHNIQUE

The ADM motor branch is microsurgically dissected and transferred to the thenar branch.

POSTOPERATIVE MANAGEMENT

After successful reinnervation, regular follow-ups and intensive physiotherapy are important for operative outcome.

RESULTS

Reconstruction of the opposition of the thumb results in improved range of motion as well as a gain of grip and pinch force.

Subterminal key pinch dynamometry: a new method to quantify strength deficit in ulnar nerve paralysis

Precise pre- and postoperative assessments are fundamental to recording the quality of recovery after ulnar nerve repair. Because of its imprecision, manual muscle testing is being replaced by dynamometry to measure grasping and key-pinch strengths. However, both grasping and key pinch are dependent not only on the ulnar nerve but also the median and radial nerves. We propose to measure strength using a new sort of pinch, called the 'subterminal key pinch'. Strength was measured using a commercially available pinch meter. Patients applied pressure on the dynamometer with the interphalangeal joint of the thumb, maintaining the joint in extension to avoid enhancement of strength by the flexor pollicis longus. We examined 17 patients before ulnar nerve repair. Preoperatively, grasping strength was 46% of normal, while key pinch was 58%, pinch-to-zoom strength was 26% and subterminal key pinch only 7%. Subterminal key pinch was the most affected pinch with a strength deficit of over 90%.Level of evidence: IV.

Dorso-palmar elongation of the diaphysis of the third metacarpal bone in prehistoric Jomon people

This study investigated cross-sectional morphological differences in the diaphysis of the third metacarpal bone (MC3) between prehistoric Jomon hunter-gatherers and modern Japanese people. Overall, 179 skeletal remains of 119 individuals (73 men and 46 women) from the Middle-to-Final Jomon period (3500 BC-500 BC) and 60 modern Japanese people (35 men and 25 women) were included in the analysis. Analyses were performed at the mid-shaft of the MC3 using linear measurement, elliptic Fourier analysis, and cross-sectional geometric properties. The standardized polar section modulus (Z_pSTD) indicated sexual differences in both populations. The right MC3 was generally stronger than the left side. There was no populational difference in the Z_pSTD in both sexes. In both men and women, the cross-sectional shape of the MC3 was relatively larger in the dorso-palmar direction than in the radioulnar direction in the Jomon population compared to the modern Japanese population. Sexual differences in cross-sectional shape were recognized only in the Jomon population, with the dorso-palmar elongation being greater in Jomon men than in women (particularly when comparing the left MC3). There was a significant side difference in the diaphyseal shape among Jomon women, with the right MC3 being relatively larger in the dorso-palmar direction. These findings were consistent, although skeletal remains of the Jomon population were excavated from different regions. Differences in the diaphyseal cross-sectional shape between populations suggest differences in habitual loading on MC3 associated with differences in subsistence behavior. Furthermore, differences in diaphyseal shape and strength between Jomon men and women suggest sexual division of labor, with men performing bimanual tasks and women performing unimanual tasks.

Assessment of grip-motion characteristics in carpal tunnel syndrome patients using a novel finger grip dynamometer system

Background

Grip strength measurement is widely used in daily medical practice, and it has been reported that the grip strength decreases in patients with carpal tunnel syndrome (CTS). However, conventional grip dynamometers evaluate only the maximum power of total grip strength and cannot measure the time course of grip motion. In this report, we aimed to determine the grip characteristics of CTS patients by measuring the time course of each finger’s grip motion and to analyze the relationship between finger grip strength and subjective symptoms using this new grip system.

Methods

The grip strength of each finger was measured using the new grip system that has four pressure sensors on the grip parts of each finger of the Smedley grip dynamometer. We analyzed the time course of grip motion and relationship between finger grip strength and subjective symptoms in 104 volunteer and 51 CTS hands. The Japanese Society for Surgery of the Hand version of the Carpal Tunnel Syndrome Instrument (CTSI-JSSH) and the Disability of Arm, Shoulder, and Hand questionnaire (DASH) were used as subjective evaluation scores.

Results

In the CTS group, the grip time with the index, middle, and ring fingers was longer, and the time at which strength was lost after reaching the maximum was earlier. Patients with severe subjective symptoms tended to not use the index and middle fingers during grip motion.

Conclusions

This new system that measures each finger’s grip strength at one time and record the time course of grip motion could quantify a patient’s symptoms easily and objectively, which may contribute to the evaluation of hand function.

Assessment of hand function using the functional dexterity test after opponensplasty in young children with Blauth type 2 hypoplastic thumb

The functional dexterity test (FDT) is a timed pegboard test based on the manipulation of each peg and suitable for young children as it is both simple and quick to perform. We assessed the postoperative FDT values for children with Blauth type 2 hypoplastic thumbs after opponensplasty. We evaluated hand function using FDT for 12 hands of 11 patients with Blauth type 2 hypoplastic thumbs. Opponensplasty was performed in all hands following by Huber's procedure. All patients were evaluated from 6 to 12 months after surgery for hand function using three types of FDT scores: time in seconds to complete the test (FDT time), combined total time with penalty seconds added to the initial time (FDT total), and the number of pegs per second to complete the task as a percentage against normative values (FDT speed). We compared the postoperative FDT scores with those for Blauth type 1 or 2 hypoplastic thumb patients without surgical treatment. FDT time and FDT total for the patients postoperatively were both significantly shorter than those in the type 2 patients without surgical treatment. FDT speed was significantly higher than that for the patients without surgical treatment. There were no significant differences in the three FDT scores between the postoperative patients and the type 1 patients. There were several limitations including small sample size, large ranges of the data, and high number of variables. FDT reflected postopponensplasty improvement in hand dexterity in young children with Blauth type 2 hypoplastic thumb.

Prior to Repair Functional Deficits in Above- and Below-Elbow Ulnar Nerve Injury

PURPOSE

Clinical deficits might vary, depending on whether an ulnar nerve lesion is above or below the elbow. Lack of strength and clawing are common manifestations of ulnar nerve paralysis. However, the magnitude of strength deficit relating to different pinch patterns and the rate and range of proximal interphalangeal extension deficits are poorly described.

METHODS

I prospectively evaluated 14 patients with above-elbow and 16 with below-elbow unrepaired ulnar nerve injuries. The completeness of flexion of the ring and little fingers was tested at the metacarpophalangeal and distal interphalangeal joints. Proximal interphalangeal joint extension lag of the ring and little fingers was assessed by goniometry, and adduction and abduction of the little finger. With dynamometers, I bilaterally evaluated grasp, key pinch, and pinch-to-zoom strength. Hand sensibility was evaluated with monofilaments.

RESULTS

Metacarpophalangeal flexion in the ulnar fingers was absent in all patients, whereas distal interphalangeal joint flexion was preserved in 29 of 30 patients. In above-elbow ulnar nerve injuries, there was no paralysis of the flexor digitorum profundus. One-third of patients exhibited no clawing. There were minimal differences between the rate of clawing and proximal interphalangeal extension lag in above- and below-elbow ulnar nerve lesions, or its occurrence in the ring or little finger. In relation to the normal hand, grasping, key pinch, and pinch-to-zoom decreased by 62%, 51%, and 75% compared with 59%, 61%, and 76% in below- and above-elbow injuries groups, respectively. In both groups, sensory deficits were predominantly over the little finger and ulnar side of the hand.

CONCLUSIONS

Minimal differences were observed in clinical deficits after above- and below-elbow ulnar nerve injuries. Hand weakness was the most frequent problem, whereas pinch-to-zoom strength was highly affected.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic IV.

Does a Hand Strength-Focused Exercise Program Improve Grip Strength in Older Patients With Wrist Fractures Managed Nonoperatively?: A Randomized Controlled Trial

OBJECTIVE

Distal radius fractures in the older population significantly impair grip strength. The aim of the study was to investigate whether a hand strength focused exercise program during the period of immobilization for nonoperatively managed distal radius fractures in this population improved grip strength and quality of life.

DESIGN

This is a single-center randomized controlled trial with concealed allocation, assessor blinding, and intention-to-treat analysis. Fifty-two patients older than 60 yrs who experienced distal radius fractures managed nonoperatively with cast immobilization. The intervention group (n = 26) received a home hand strength-focused exercise program from 2 and 6 wks after injury while immobilized in a full short arm cast. The control group (n = 26) performed finger range of motion exercises as per protocol. Primary outcome was grip strength ratio of injured arm compared with uninjured arm. Secondary outcome included functional scores of the 11-item shortened version of the Disabilities of the Arm, Shoulder and Hand. Outcomes were measured at 2, 6, and 12 wks after injury.

RESULTS

The intervention group significantly improved grip strength ratio at both 6 and 12 wks (6 wks: 40% vs 25%, P = 0.0044, and 12 wks: 81% vs 51%, P = 0.0035). The intervention group improved the 11-item Disabilities of the Arm, Shoulder and Hand score at 12 wks; however, this was not statistically significant (25 vs 40, P = 0.066).

CONCLUSIONS

A hand strength-focused exercise program for elderly patients with distal radius fractures while immobilized significantly improved grip strength.

Repair Method for Complete High Ulnar Nerve Injury Based on Nerve Magnified Regeneration

PURPOSE

Complete high ulnar nerve injury can cause serious sequelae, including residual sensation and loss of movement and especially dysfunction of the intrinsic muscles of the hand. As a solution to treat complete high ulnar nerve injury, we proposed a new repair method for ulnar nerve injury based on nerve-magnified regeneration.

METHODS

Twenty-two patients with complete division of the ulnar nerve at a high level who were treated from May 2013 to December 2016 were divided into two groups. The proposed repair method for complete high ulnar nerve injury was performed in group I (11 patients), while the traditional repair method, ie, repair of the original injury site of the ulnar nerve, was used in group II (11 patients).

RESULTS

The results showed no significant difference in the mean sensory scores assigned by the Highet-Zachary scheme (the Highet Scale) between the two groups. The mean Highet Scale score of muscle strength for the first dorsal interosseus muscle was significantly better in group I than that in group II (p=0.010). In group I, 10 of 11 patients were graded as M4 or M5. Grip strength, pinch strength, and the Disabilities of the Arm, Shoulder, and Hand (DASH) score were significantly better in group I than those in group II (p<0.01).

CONCLUSION

Therefore, this method for complete high ulnar nerve injury based on nerve-magnified regeneration can shorten the path of motor nerve regeneration, effectively reduce atrophy of the intrinsic muscles of the hand, and provide better hand function.

Age- and gender-stratified adult myometric reference values of isometric intrinsic hand strength

STUDY DESIGN

Descriptive normative.

INTRODUCTION

Intrinsic hand strength can be impacted by hand arthritis, peripheral nerve injuries, and spinal cord injuries. Grip dynamometry does not isolate intrinsic strength, and manual muscle testing is not sensitive to change in grades 4 and 5. The Rotterdam Intrinsic Hand Myometer is a reliable and valid test of intrinsic hand strength; however, no adult normative data are available.

PURPOSE OF THE STUDY

To describe age- and gender-stratified intrinsic hand strength norms in subjects aged 21 years and above and to determine if factors known to predict grip dynamometry also predict measures of intrinsic hand strength.

METHODS

Three trials of 5 measures of maximal isometric intrinsic strength were performed bilaterally by 607 "healthy-handed" adult males and females. Average strength values were stratified by age and gender. Data were analyzed to determine the influence of demographic and anthropometric variables on intrinsic strength.

RESULTS

Intrinsic strength generally followed age and gender trends similar to grip dynamometry. Age, gender, body mass index, and the interaction between gender and body mass index were predictors of intrinsic strength, whereas in most cases, the hand being tested did not predict the intrinsic strength.

DISCUSSION

With the addition of these findings, age- and gender-stratified hand intrinsic strength norms now span from age 4 through late adulthood. Many factors known to predict grip dynamometry also predict intrinsic myometry. Additional research is needed to evaluate the impact of vocational and avocational demands on intrinsic strength.

CONCLUSIONS

These norms can be referenced to evaluate and plan hand therapy and surgical interventions for intrinsic weakness.

Distal nerve transfer for thenar palsy: A cadaveric study

INTRODUCTION

Severe proximal median nerve palsies often result in irreversible thenar atrophy and thumb abduction function loss. Tendon transfer involves substantial limitations and challenges; but, distal nerve transfer may provide an alternative treatment. Our goal was to validate the anatomical suitability of two distal ulnar nerve branches for thenar muscle reanimation.

MATERIALS AND METHODS

We assessed nerve transfer to the recurrent branch of median nerve (RMN) in 16 embalmed cadaveric hands. The ulnar motor branch to the flexor digiti minimi brevis (FDMBn) and the ulnar motor branch to the third lumbrical (3rdLn) were assessed for transfer. Coaptation success was measured by the overlap of the nerve donor with the RMN and correspondence of nerve diameters.

RESULTS

The mean transferable length and width of the RMN were 20.7 ± 4.5 and 1.0 ± 0.3 mm, respectively. We identified an average of three branches in the branching anatomy from the ulnar nerve to the hypothenar muscles. The maximal transferable lengths and widths of the FDMBn and the 3rdLn were 13.8 ± 4.4 and 0.5 ± 0.1 mm and 24.1 ± 6.4 and 0.4 ± 0.1 mm, respectively. The overlap with the RMN of the FDMBn and 3rdLn was 9.0 ± 3.6 (2.0-15.3) and 17.8 ± 6.0 (4.7-27.5) mm, respectively.

CONCLUSIONS

This anatomical study demonstrates the feasibility of distal nerve transfers between the ulnar and median nerves in the hand for reanimation of thenar muscles. Ulnar motor donors of the BrFDMBn and 3rdLn likely represent the least morbid donors with short distances for regeneration and a single coaptation repair.

Assessment of the Passive Tension of the First Dorsal Interosseous and First Lumbrical Muscles Using Shear Wave Elastography

PURPOSE

Quantitative evaluation of passive tension of the intrinsic muscles of the hand is necessary to assess contracture of the intrinsic muscles accurately. The aim of this study was to evaluate the shear modulus, which is related to passive muscle tension, of the first dorsal interosseous (FDI) and first lumbrical (FL) muscles using shear wave elastography.

METHODS

Subjects were 18 healthy males. The shear modulus of the FDI and FL muscles was assessed at several proximal interphalangeal (PIP), distal interphalangeal (DIP), metacarpophalangeal (MCP), and wrist joint positions. The position in which the MCP joint was flexed 60° past 0° with PIP-DIP joint extension and that in which the MCP joint was extended 30° past 0° with PIP-DIP joint flexion were respectively defined as the slack and stretched positions. We analyzed whether the shear modulus was affected by finger position (slack or stretched), wrist position (30° flexion past 0° and 30° extension past 0°), and muscle (FDI or FL).

RESULTS

Shear modulus in the stretched position was significantly higher than that in the slack position. The shear modulus of the FL muscle at 30° wrist extension was significantly higher than that at 30° flexion. The shear modulus of the FL muscle was significantly higher than that of the FDI muscle in the stretched position with the wrist at 30° flexion and extension, and in the slack position with the wrist at 30° extension.

CONCLUSIONS

The shear modulus of the FDI and FL muscles increased with MCP joint extension and PIP-DIP joint flexion. The difference in the muscle characteristics between the FDI and FL muscles should be considered when evaluating or treating contractures of the intrinsic muscles.

CLINICAL RELEVANCE

Shear wave elastography can evaluate the condition of the intrinsic muscles of the hand quantitatively.

Quantification of hand function by power grip and pinch strength force measurements in ulnar nerve lesion simulated by ulnar nerve block

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.

Quantification of weakness caused by distal median nerve lesion by dynamometry

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.

Transcutaneous high-frequency alternating current for rapid reversible muscle force reduction below pain threshold

OBJECTIVE

The development of non-invasive, quickly reversible techniques for controlling undesired muscle force production (e.g. spasticity) could expand rehabilitation approaches in those with pathology by increasing the type and intensity of exercises that can be performed. High-frequency alternating current (HFAC) has been previously established as a viable method for blocking neural conduction in peripheral nerves. However, clinical application of HFAC for nerve conduction block is limited due to the invasiveness of surgical procedures and the painful onset response. This study aimed to examine the use of transcutaneous HFAC (tHFAC) at various stimulation frequencies to address these shortfalls.

APPROACH

Ten individuals participated in the study. Surface electrodes were utilized to apply tHFAC (0.5-12 kHz) to the median and ulnar nerves. Individual pain threshold was determined by gradual increase of stimulation amplitude. Subjects then performed a force-matching task by producing grip forces up to the maximal voluntary contraction level with and without application of tHFAC below the pain threshold.

MAIN RESULTS

Pain threshold current amplitude increased linearly with stimulation frequency. Statistical analysis showed that both stimulation frequency and charge injected per phase had significant effects (p   <  0.05) on grip force reduction. At the group level, application of tHFAC below pain threshold reduced grip force by a maximum of 40.7%  ±  8.1%. Baseline grip force trials interspersed between tHFAC trials showed consistent grip force, indicating that fatigue was not a factor in force reduction.

SIGNIFICANCE

Our results demonstrate the effectiveness of tHFAC at reducing muscle force when applied below the pain threshold, suggesting its potential clinical viability. Future studies are necessary to further elucidate the mechanism of force reduction before clinical application.

The Biomechanical Basis of the Claw Finger Deformity: A Computational Simulation Study

PURPOSE

Claw finger deformity occurs during attempted finger extension in patients whose intrinsic finger muscles are weakened or paralyzed by neural impairments. The deformity is generally not acutely present after intrinsic muscle palsy. The delayed onset, with severity progressing over time, suggests soft tissue changes that affect the passive biomechanics of the hand exacerbate and advance the deformity. Clinical interventions may be more effective if such secondary biomechanical changes are effectively addressed. Using a computational model, we simulated these altered soft tissue biomechanical properties to quantify their effects on coordinated finger extension.

METHODS

To evaluate the effects of maladaptive changes in soft tissue biomechanical properties on the development and progression of the claw finger deformity after intrinsic muscle palsy, we completed 45 biomechanical simulations of cyclic index finger flexion and extension, varying the muscle excitation level, clinically relevant biomechanical factors, and wrist position. We evaluated to what extent (1) increased joint laxity, (2) decreased mechanical advantage of the extensors about the proximal interphalangeal joint, and (3) shortening of the flexor muscles contributed to the development of claw finger deformity in an intrinsic-minus hand model.

RESULTS

Of the mechanisms studied, shortening (or contracture) of the extrinsic finger flexors was the factor most associated with the development of claw finger deformity in simulation.

CONCLUSIONS

These simulations suggest that adaptive shortening of the extrinsic finger flexors is required for the development of claw finger deformity. Increased joint laxity and decreased extensor mechanical advantage only contributed to the severity of the deformity in simulations when shortening of the flexor muscles was present.

CLINICAL RELEVANCE

In both the acute and chronic stages of intrinsic finger paralysis, maintaining extrinsic finger flexor length should be an area of focus in rehabilitation to prevent formation of the claw finger deformity and achieve optimal outcomes after surgical interventions.

Intertrial Rest for Maximum Grip and Key Pinch Strength in Japanese Young Adults

OBJECTIVE

This study investigated the most appropriate intertrial rest period for maximum grip and key pinch strength measurements involving three trials.

METHOD

The study included 40 male and 40 female participants. Using a repeated-measures design, six intertrial rest periods-15 s, 30 s, 60 s, 90 s, 120 s, and 150 s-were investigated, one per day on 6 different days.

RESULTS

A repeated-measures analysis of variance or Friedman test found significant decreases in grip and key pinch strength over the three trials in all test conditions. However, for both hands, only small differences were observed in test conditions (≥90 s, male grip; ≥60 s, female grip; male and female key pinch; effect sizes of <0.5).

CONCLUSION

If a rest of ≥150 s is not possible, 90 s of rest between trials for grip strength and 60 s of rest between trials for key pinch strength can be considered.

Transferring the Motor Branch of the Opponens Pollicis to the Terminal Division of the Deep Branch of the Ulnar Nerve for Pinch Reconstruction

PURPOSE

With ulnar nerve injuries, paralysis of the first dorsal interosseous (FDI) and the adductor pollicis (ADP) muscles weakens pinch. The likelihood that these muscles will be reinnervated following ulnar nerve repair around the elbow is very low. To overcome this obstacle, we propose a more distal repair: transferring the opponens pollicis motor branch (OPB) to the terminal division of the deep branch of the ulnar nerve (TDDBUN).

METHODS

We dissected 10 embalmed hands to study the anatomy of the thenar branches of the median nerve and TDDBUN. We also operated on 3 patients with recent ulnar nerve injuries around the elbow, suturing the ulnar nerve and transferring the OPB to the TDDBUN. Before and after surgery, we measured grasp, key pinch, and pinch-to-zoom strength using dynamometers. Pinch-to-zoom gesture consists of moving the index finger and thumb pulp toward each other for zooming out of an image on screen. Patients were followed for at least 15 months.

RESULTS

The thenar branch of the median nerve innervated the abductor pollicis brevis and opponens pollicis in all specimens, but only half the superficial head of the flexor pollicis brevis. The TDDBUN gave off a single motor branch to the transverse head of the ADP, 1 or 2 branches to the oblique head, and a final branch to the FDI. The ratio of myelinated fibers between the OPB and the TDDBUN was 3:5. Relative to the normal side, pinch-to-zoom strength was mostly affected by the ulnar nerve lesion, with strength decreased by 80% to 90%. After surgery, we observed reinnervation of the FDI and an 80% to 90% improvement in pinch-to-zoom strength.

CONCLUSIONS

Transferring the OPB to the TDDBUN provided reinnervation of the FDI and ADP, thereby contributing to pinch strength improvement.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic V.

Zancolli procedure and nerve repair with sural graft as a treatment for patient with claw hand due to complete rupture of ulnar and median nerve: A case report

•

This case is very devastating due to loss of hand function to the extreme level due to combined injury of ulnar and median nerve.

•

There have been very few documentations about this type of injury in English literatures.

•

This combination technique of surgery provide excellent outcome for the patient.

Introduction

Combined injuries of peripheral nerve of upper extremity are usually the result of severe trauma to the extremity, and are often associated with substantial soft tissue, vascular, and bony injuries. The most common form of such combined injury is a low median-ulnar palsy, usually due to laceration of the volar wrist. It is a devastating injury, and with delayed presentation the injury is going to be more difficult to reconstruct.

Presentation of case

Ten-year-old girl was admitted to hospital with numbness of her left palm and fingers, 5 months before admission. She was hit by a car while riding a bicycle from opposite direction from she was heading and cut her left forearm by licensed plate. Initially treated at nearby clinic but later couldn’t extend her fingers after the pain subsided and left untreated for 5 months.

Discussion

Traditionally, number of static procedures have been described to correct the claw hand deformity by preventing MCP joint hyperextension. Nevertheless, these procedures are reserved for those having ability to extend IP joints while MCP joint hyperextension were prevented. Conversely, static procedure like Zancolli capsulodesis is simple and do not sacrifice any motors in an already compromised extremity. Combined with sural graft, the outcome for the patient is hopefully better than Zancolli procedure alone.

Conclusion

Zancolli procedure along with nerve repair with sural graft as a treatment of claw hand due to complete rupture of ulnar and median nerve is one of feasible treatment options to correct claw hand deformity with such combined palsy.

Force distribution of a cylindrical grip differs between dominant and nondominant hand in healthy subjects

INTRODUCTION

Grip strength and load distribution of the hand are important parameters for evaluating hand function. The purpose of this study was to analyze and compare grip force and load distribution of dominant and nondominant hands in right-handed healthy subjects.

METHODS

Gripping measurements were performed on 40 healthy right-handed subjects using a cylindrical gripping device. Two different cylinders with circumferences of 150 mm (small cylinder) and 200 mm (large cylinder), respectively, were used for the measurements. Subjects were assigned to either the small or the large cylinder with respect to their hand size. Maximum and mean force applied during three intervals of gripping as well as the percent contribution of each digit, thenar, and hypothenar in relation to the total load applied were acquired. Values of dominant and nondominant hands were compared.

RESULTS

Percent contribution of mean grip strength differed for the thumb (p = 0.007), ring finger (p < 0.001), little finger (p = 0.047), and palm (p < 0.001). Comparing the dominant and nondominant side, the dominant hand showed a lower contribution of the thumb, ring finger, and little finger, but a higher contribution of the palm. When analyzing maximum grip, percent contribution of the small fingers was equal between dominant and nondominant side (p = 0.1). Differences between dominant and nondominant thumb, ring finger, and palm persisted (p = 0.007, p = 0.001, p = 0.005, respectively). No differences could be shown for the index finger, middle finger, thenar, and hypothenar when analyzing both mean and maximum force.

DISCUSSION AND CONCLUSION

Percent contribution of the thumb and the fingers to total grip strength differed between dominant and nondominant hands with a change in distribution when assessing maximum grip force. In right-handed subjects, thumb and ring finger have important roles during gripping.

Technical development of transcutaneous electrical nerve inhibition using medium-frequency alternating current

Background

Innovative technical approaches to controlling undesired sensory and motor activity, such as hyperalgesia or spasticity, may contribute to rehabilitation techniques for improving neural plasticity in patients with neurologic disorders. To date, transcutaneous electrical stimulation has used low frequency pulsed currents for sensory inhibition and muscle activation. Yet, few studies have attempted to achieve motor nerve inhibition using transcutaneous electrical stimulation. This study aimed to develop a technique for transcutaneous electrical nerve inhibition (TENI) using medium-frequency alternating current (MFAC) to suppress both sensory and motor nerve activity in humans.

Methods

Surface electrodes were affixed to the skin of eight young adults to stimulate the median nerve. Stimulation intensity was increased up to 50% and 100% of the pain threshold. To identify changes in sensory perception by transcutaneous MFAC (tMFAC) stimulation, we examined tactile and pressure pain thresholds in the index and middle fingers before and after stimulation at 10 kHz. To demonstrate the effect of tMFAC stimulation on motor inhibition, stimulation was applied while participants produced flexion forces with the index and middle fingers at target forces (50% and 90% of MVC, maximum voluntary contraction).

Results

tMFAC stimulation intensity significantly increased tactile and pressure pain thresholds, indicating decreased sensory perception. During the force production task, tMFAC stimulation with the maximum intensity immediately reduced finger forces by ~ 40%. Finger forces recovered immediately after stimulation cessation. The effect on motor inhibition was greater with the higher target force (90% MVC) than with the lower target (50% MVC). Also, higher tMFAC stimulation intensity provided a greater inhibition effect on both sensory and motor nerve activity.

Conclusion

We found that tMFAC stimulation immediately inhibits sensory and motor activity. This pre-clinical study demonstrates a novel technique for TENI using MFAC stimulation and showed that it can effectively inhibit both sensory perception and motor activity. The proposed technique can be combined with existing rehabilitation devices (e.g., a robotic exoskeleton) to inhibit undesired sensorimotor activities and to accelerate recovery after neurologic injury.

Can upper limb taping or exercises improve hand function, writing speed and self-perception of performance in adolescent school children?

BACKGROUND

The majority of students spend time in writing, which is a prime performance measure in examinations. Enhancement in handwriting should benefit students to attain better academic performance.

OBJECTIVE

To assess the effectiveness of taping and exercises on hand function, writing speed, self-perception of writing and to compare these techniques.

METHODS

A randomized control trial was conducted using cluster sampling in adolescent children across four schools in an urban city. A 4-week intervention study was conducted on 123 students divided into taping, exercise and control groups. Outcome measures were grip strength, pinch strength, 12-min writing speed test and the Writer Self-Perception Scale (WSPS). For intra-group analysis, a paired t-test was used for parametric values and the Wilcoxon signed rank test was used for non-parametric values. For inter-group analysis, one-way analysis of variance (ANOVA) for parametric values and the Kruskal-Wallis test for non-parametric values was used.

RESULTS

The taping group showed a significant improvement in grip strength (1.79 kg; p = 0.00), pinch strength [1.67 lb (757.4 g); p = 0.00] and writing speed (39.77 words/12 min; p = 0.00). The exercise group showed significant improvement in grip strength (2.09 kg; p = 0.00), pinch strength (1.28 lb; p = 0.00), writing speed (28.38 words/12 min; p = 0.00). In the control group, there was a significant increase in pinch strength (1.023 lb; p = 0.01) and writing speed (12.94 words/12 min; p = 0.02). Inter-group analysis showed significant difference in writing speed (p = 0.002) and grip strength (p = 0.00). There was no significant difference in perception (p = 0.071).

CONCLUSION

Taping and exercise are equally effective for enhancement of hand function, writing speed and self-perception in adolescent school children.

Load distribution of the hand during cylinder grip analyzed by Manugraphy

STUDY DESIGN

Clinical measurement and basic research.

INTRODUCTION

Manugraphy allows assessing dynamically all forces applied perpendicular to a cylinder surface by the whole contact area of the hand with a high spatial resolution.

PURPOSE OF THE STUDY

To identify the physiological load distribution of the whole contact area of the hand during cylinder grip.

METHODS

A sample of 152 healthy volunteers performed grip force tests with 3 cylinder sizes of the Manugraphy system (novel, Munich, Germany) on 3 different days. The whole contact area of the hand was sectioned into 7 anatomic areas, and the percent contribution of each area in relation to the total load applied was calculated. The load distribution of the dominant and nondominant hands and with different cylinder sizes was compared. Furthermore, the load distribution between the finger phalanges of each finger was analyzed.

RESULTS

The results for the dominant and nondominant hands were in all 7 areas of the hand similar with the percent contribution differing within a range of 1%-4% (P > .138). Load distribution changed significantly with different cylinder sizes: all 7 areas differed between 1% and 7% with P < .001, most pronounced for the thumb. The load distribution of the phalanges showed that the contribution of the distal phalanges increased with ascending cylinder size, whereas the contribution of the proximal phalanges decreased. The interindividual variability of the load distribution pattern was noticeable.

DISCUSSION

For the clinical practice, Manugraphy might be a useful supplement to traditional grip force measurement for identifying the individual characteristics of a patient's dysfunction and monitoring the progress of hand rehabilitation.

CONCLUSIONS

There is no universal or typical load distribution pattern of the hand but only an individual pattern. To evaluate a compromised hand, it is permissible to compare it with the healthy opposite hand as a reference. Several cylinder sizes should be used for load distribution testing. Using smaller handles in the daily life can help to compensate impairment of the thumb and fingertips.

LEVEL OF EVIDENCE

2.

Transfer of the Motor Branch of the Abductor Digiti Quinti for Thenar Muscle Reinnervation in High Median Nerve Injuries

PURPOSE

In high median nerve repairs, thenar muscle reinnervation is impossible because of the long distances over which axons must regenerate. To overcome this obstacle, we propose transferring the abductor digiti quinti motor branch (ADQMB) to the thenar branch of the median nerve (TBMN).

METHODS

We used 10 embalmed hands for anatomical and histological studies. Thereafter, 5 patients with a high median nerve injury underwent surgical reconstruction within 8 months of their accident and were followed for at least 10 months after surgery (mean, 13.2 months). We transferred the ADQMB to the TBMN. The median nerve was grafted in 4 patients and the motor branch of the extensor carpi radialis brevis was transferred to the anterior interosseous nerve in 3. Patients had pre- and postoperative evaluations of thumb range of motion and strength.

RESULTS

In cadaveric hands, the ADQMB was the first branch of the ulnar nerve to arise near the pisiform bone. The TBMN arose from the anterior surface of the median nerve, underneath the flexor retinaculum. Retrograde dissection of the TBMN allowed tension-free coaptation with the ADQMB. Both branches contained approximately 650 myelinated fibers. After surgery, all our patients improved thumb pronation, thenar eminence bulk, and abductor pollicis brevis British Medical Research Council score. They recovered approximately 75% of their normal-side grasp and pinch strength. No patient lost little finger abduction.

CONCLUSIONS

Transfer of the ADQMB to the TBMN reinnervated the thenar muscles, which improved thumb range of motion and strength.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic V.

Reference values of intrinsic muscle strength of the hand of adolescents and young adults

STUDY DESIGN

A cross-sectional clinical measurement study.

INTRODUCTION

Measuring intrinsic hand muscle strength helps evaluate hand function or therapeutic outcomes. However, there are no established normative values in adolescents and young adults between 13 and 20 years of age.

PURPOSE OF THE STUDY

To measure hand intrinsic muscle strength and identify associated factors that may influence such in adolescents and young adults through use of the Rotterdam intrinsic hand myometer.

METHODS

A total of 131 participants (male: 63; female: 68) between 13 and 20 years of age completed the strength measurements of abductor pollicis brevis, first dorsal interosseus (FDI), deep head of FDI and lumbrical of second digit, flexor pollicis brevis (FPB), and abductor digiti minimi. Two trials of the measurements of each muscle were averaged for analyses. Self-reported demographic data were used to examine the influences of age, sex, and body mass index (BMI) on intrinsic hand muscle strength.

RESULTS

Normative values of intrinsic hand muscle strength were presented by age groups (13, 14, 15-16, 17-18, 19-20 year olds) for each sex category (male, female). A main effect of sex, but not age, on all the muscles on both the dominant (FPB: P = .02, others: P < .001) and non-dominant (FDI: P = .005, FPB: P = .01, others: P < .001) sides was found. A significant effect of BMI was found on dominant (P = .009) and non-dominant abductor pollicis brevis (P = .002). In addition, FDI (P = .005) and FPB (P = .002) were stronger on the dominant side than the non-dominant side.

DISCUSSION

Intrinsic hand muscle strength may be influenced by different factors including sex, BMI, and hand dominance. A larger sample is needed to rigorously investigate the influence of age on intrinsic strength in male and female adolescents and young adults.

CONCLUSION

The results provide reference values and suggest factors to be considered when evaluating hand function and therapeutic outcomes in both clinical and research settings. Further study is recommended.

LEVEL OF EVIDENCE

VI.