Dorsal Interosseus Research Articles

Alterations of hand sensorimotor function and cortical motor representations over the adult lifespan.

Using a cross sectional design, we aimed to identify the effect of aging on sensorimotor function and cortical motor representations of two intrinsic hand muscles, as well as the course and timing of those changes. Furthermore, the link between cortical motor representations, sensorimotor function, and intracortical inhibition and facilitation was investigated. Seventy-seven participants over the full adult lifespan were enrolled. For the first dorsal interosseus (FDI) and abductor digiti minimi (ADM) muscle, cortical motor representations, GABAA-mediated short-interval intracortical inhibition (SICI), and glutamate-mediated intracortical facilitation (ICF) were assessed using transcranial magnetic stimulation over the dominant primary motor cortex. Additionally, participants’ dexterity and force were measured. Linear, polynomial, and piecewise linear regression analyses were conducted to identify the course and timing of age-related differences. Our results demonstrated variation in sensorimotor function over the lifespan, with a marked decline starting around the mid-thirties. Furthermore, an age-related reduction in cortical motor representation volume and maximal MEP of the FDI, but not for ADM, was observed, occurring mainly until the mid-forties. Area of the cortical motor representation did not change with advancing age. Furthermore, cortical motor representations, sensorimotor function, and measures of intracortical inhibition and facilitation were not interrelated.

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

PurposeComplete 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.MethodsTwenty-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).ResultsThe 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).ConclusionTherefore, 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.

Electrophysiological Evaluation and Clinical Implication of Martin-Gruber Anastomosis in Healthy Subjects.

Background: The aim of this study is to determine the prevalence of Martin-Gruber Anastomosis (MGA) in healthy Egyptian subjects, and to discuss the available literature regarding MGA subtypes and their clinical implications. Methods: An electrophysiological study was conducted in both forearms of 140 healthy subjects. This included the ulnar and median nerves. Compound muscle action potentials were recorded from abductor pollicis brevis, abductor digiti minimi, and first dorsal interosseous muscles. Other measurements included the compound motor action potential amplitude and its innervation ratio. Results: MGA was found in 56 of the 280 forearms. This included 20 men and 36 women. Type II MGA subtype was the most frequent in both genders. The MGA was bilateral in 6 subjects and more frequent on the right side. The highest mean amplitude and innervation ratio were recorded at first dorsal interosseus muscle. Conclusions: The prevalence of MGA in the studied sample of the Egyptian population is 20%. It is important for Hand, Orthopaedic and Neurosurgeons to be aware of this anatomic variation in order to explain paradoxical motor and sensory loss in patients.

An Additional Electrodiagnostic Tool for Ulnar Neuropathy: Mixed across the Elbow.

Background Diagnosing ulnar neuropathy at the elbow (UNE) remains challenging despite guidelines from national organizations. Motor testing of hand intrinsic muscles remains a common diagnostic method fraught with challenges. Objective The aim of the study is to demonstrate utility of an uncommon nerve conduction study (NCS), mixed across the elbow, when diagnosing UNE. Methods Retrospective analysis of 135 patients, referred to an outpatient University-based electrodiagnostic laboratory with suspected UNE between January 2013 and June 2019 who had motor to abductor digiti minimi (ADM), motor to first dorsal interosseus (FDI), and mixed across the elbow NCS completed. To perform the mixed across the elbow NCS, the active bar electrode was placed 10-cm proximal to the medial epicondyle between the biceps and triceps muscle bellies. The median nerve was stimulated at the wrist followed by stimulation of the ulnar nerve at the ulnar styloid. The difference between peak latencies, labeled the ulnar-median mixed latency difference (U-MLD), was used to evaluate for correlation between the nerve conduction velocities (NCV) of ADM and FDI. Results Pearson r -values = −0.479 and −0.543 ( p < 0.00001) when comparing U-MLD to ADM and FDI NCV across the elbow, respectively. The negative r -value describes the inverse relationship between ulnar velocity across the elbow and increasing U-MLD. Conclusion Mixed across the elbow has moderate–strong correlation with ADM and FDI NCV across the elbow. All three tests measure ulnar nerve function slightly differently. Without further prospective data, the most accurate test remains unclear. The authors propose some combination of the three tests may be most beneficial when diagnosing UNE.

Impact of disuse muscular atrophy on the compound muscle action potential.

Disuse atrophy from immobilization is the result of decreased neural activity and muscle unloading. We studied the impact of disuse on hand intrinsic compound muscle action potentials (CMAPs) in a cohort of 39 patients with unilateral 6-week immobilization of the hand in a cast, after distal radius fracture. We excluded patients with nerve injury. We compared side-to-side CMAP characteristics at the time of cast removal and at a subsequent follow-up visit, after a mean interval of 7.8 weeks. Statistically significant reductions in CMAP amplitude were noted for the abductor pollicis brevis (29.2%), abductor digiti minimi (19.0%), and first dorsal interosseus (24.9%). There was partial repair of the relative CMAP reduction at the follow-up visit (20.1%, 10.7%, and 8.7%, respectively). There was no significant change in CMAP duration. These results provide a framework for quantifying the degree of hand intrinsic CMAP amplitude reduction attributed to disuse.

Aftereffects of Intermittent Theta-Burst Stimulation in Adjacent, Non-Target Muscles

To assess motor cortex neurophysiology, including the mechanisms of neuroplasticity, transcranial magnetic stimulation (TMS) is typically applied to the motor “hotspot”— the optimal site for inducing a twitch in a given target muscle. It is known that the effects of suprathreshold repetitive TMS (rTMS) spread along functional connections beyond the specific cortical stimulation target, and yet, it is unknown whether the aftereffects of subthreshold intermittent theta-burst stimulation (iTBS), an ultra-high frequency patterned rTMS protocol, extend beyond the targeted muscle.We investigated whether and to what extent iTBS induces changes in the cortical output to other intrinsic hand muscles with adjacent cortical representation to the target. Sixteen healthy adults underwent neuronavigated TMS-iTBS targeting the first dorsal interosseus (FDI) hotspot. Proportion of motor evoked potentials (MEPs) at the resting motor threshold (RMT), baseline MEP amplitude, and iTBS-induced changes in MEP amplitude were compared between FDI, abductor pollicis brevis (APB) and abductor digiti minimi (ADM) muscles. MEP amplitudes recorded from the three muscles at RMT and suprathreshold intensities indicated the chosen hotspots were relatively selective for FDI. Nevertheless, iTBS induced significant facilitation of MEPs recorded from both FDI and APB, but not ADM. Surprisingly, the MEP modulation was greater in APB, even when controlling for the baseline MEP amplitude. These results indicate that iTBS modulation of cortico-spinal excitability extends beyond the representation of the targeted muscle. Results have implications both for how iTBS may be used in clinical treatment and for the safety guidelines for the application of iTBS.

Fibularis Tertius: Anatomical Study and Review of the Literature

Although there is much morphological variation in the anterior compartment of the leg, there is little information about the morphological variability of the fibularis tertius muscle (FTM). The main aim of the present study was to characterize the morphology (origin and insertion) and frequency of occurrence of the FTM and to use these findings as the basis for a new classification of the fibularis tertius tendon. Classical anatomical dissection was performed on 106 lower limbs fixed in 10% formalin. The presence of the FTM and the morphology of both its origin and its insertion were described. The FTM was present in 91 limbs (85.8%). Three types of origin were observed: Type 1, the most common type, with its origin on the distal half fibula (67%); Type 2, with the origin on the distal third fibula (22%); and Type 3, with an origin from the tendon of the extensor digitorum longus (11%). In addition, six types of insertion were distinguished. The most common was Type I (45%), a single distal attachment where the tendon inserts into the shaft of the fifth metatarsal bone. The rarest was Type VI, characterized by fusion with an additional band of the fibularis brevis tendon, which gives rise to the fourth interosseus dorsalis muscle. Two morphological variants of insertion could be distinguished, fan-shaped and band-shaped. Both the origin and insertion of the FTM are very morphologically variable, with three types of origin (Types 1-3) and six types of insertion point (Types I-VI) observed. Knowledge of such variations is essential for both clinicians and anatomists. Clin. Anat. 32:1082-1093, 2019. © 2019 Wiley Periodicals, Inc.

Surface electromyography of the foot: A protocol for sensor placement

BackgroundThe use of surface EMG (sEMG) to record muscle activity is common place yet due to restrictions in technology studies on the intrinsic foot muscles have been limited or only fine wire instruments have been used. AimThis paper looks at the potential reliability of a sEMG protocol for assessing the intrinsic foot muscles. MethodsSix intrinsic muscles were defined using ultrasound and muscle function testing. A protocol for sensor placement was created with repeatability and reliability testing of the protocol conducted by three separate testers on three subjects over two different time frames. Inter tester and Inter session repeatability and reliability was measured with ICC and percentage standard error of measurement. ResultsAlthough there was good correlation between Extensor Digitorum Brevis, Dorsal Interossei, Abductor Digiti Minimi and Flexor Digitorum Brevis there was increased variability and poor correlation for Flexor hallucis Brevis and Abductor Hallucis. The percentage standard error of measurement did not support the high ICC values indicating a lower precision of measurement. SignificanceVariability between testers and sessions shows an inconsistent reliability of sEMG and further work is required with protocols focussing on grouping muscles to improve the understanding of the intrinsic foot muscles.

Intensive virtual reality and robotic based upper limb training compared to usual care, and associated cortical reorganization, in the acute and early sub-acute periods post-stroke: a feasibility study

BackgroundThere is conflict regarding the benefits of greater amounts of intensive upper limb rehabilitation in the early period post-stroke. This study was conducted to test the feasibility of providing intensive therapy during the early period post-stroke and to develop a randomized control trial that is currently in process. Specifically, the study investigated whether an additional 8 h of specialized, intensive (200–300 separate hand or arm movements per hour) virtual reality (VR)/robotic based upper limb training introduced within 1-month post-stroke resulted in greater improvement in impairment and behavior, and distinct changes in cortical reorganization measured via Transcranial Magnetic Stimulation (TMS), compared to that of a control group.MethodsSeven subjects received 8–1 h sessions of upper limb VR/robotic training in addition to their inpatient therapy (PT, OT, ST). Six subjects only received their inpatient therapy. All were tested on measures of impairment [Upper Extremity Fugl-Meyer Assessment (UEFMA), Wrist AROM, Maximum Pinch Force], behavior [Wolf Motor Function Test (WMFT)], and also received TMS mapping until 6 months post training. ANOVAs were conducted to measure differences between groups across time for all outcome measures. Associations between changes in ipsilesional cortical maps during the early period of enhanced neuroplasticity and long-term changes in upper limb impairment and behavior measures were evaluated.ResultsThe VR/robotic group made significantly greater improvements on UEFMA and Wrist AROM scores compared to the usual care group. There was also less variability in the association between changes in the First Dorsal Interosseus (FDI) muscle map area and WMFT and Maximum Force change scores for the VR/robotic group.ConclusionsAn additional 8 h of intensive VR/robotic based upper limb training initiated within the first month post-stroke may promote greater gains in impairment compared to usual care alone. Importantly, the data presented demonstrated the feasibility of conducting this intervention and multiple outcome measures (impairment, behavioral, neurophysiological) in the early period post-stroke.

A high-density surface EMG framework for the study of motor neurons controlling the intrinsic and extrinsic muscles of the hand.

We propose a framework based on high-density surface electromyography (HD-sEMG) to identify the neural drive to muscles controlling the human hand. High-density (320 channels) sEMG signals were recorded concurrently from intrinsic (the four dorsal interossei and thenar) and extrinsic (forearm) hand muscles and then decomposed into the constituent trains of motor unit (MU) action potentials. The participants performed pinch tasks with simultaneous activation of the thumb and one of the other fingers with sinusoidal force variations. The common drive among MUs across different muscles was extracted via principal component analysis (PCA) of the smoothed MU discharge rates. The first principal component of the smoothed discharge rates of all identified motor neurons explained 48.7 ± 15.4% of the total variance across all pinching tasks, indicating a common neural input shared by different muscles of the forearm and the hand.. When considering only the MUs extracted from extrinsic and intrinsic muscles, the percent of variance explained was 48.3 ± 15.3% and 57.1 ± 15.5%, respectively. This framework is conceived to use motor neuron activity for a proportional myoelectric control and rehabilitation technologies. A wearable adaptation of the framework is proposed for future perspectives.

Anatomical Pattern of Dorsal Metatarsal Arteries in a Black Kenyan Population

Introduction Knowledge of anatomical variations in the origin and in the course of the dorsal metatarsal arteries (DMTAs) is valuable for many procedures, including reconstructive surgeries and flap selection. However, there is a paucity of data on these arteries among black Africans. Materials and Methods The present study studied the origin and the location of DMTAs in 30 formalin-fixed cadaveric feet of adult black Kenyans at the Department of Human Anatomy of the University of Nairobi, Nairobi, Kenya. Results Dorsal metatarsal arteries were present in all of the cases. Of the right dorsalis pedis artery (DPA), in the majority of the cases, the 1st DMTA arose as the continuation of the DPA, while the 2nd to 4th DMTAs were given off as branches from the arcuate artery (AA). On the left feet, in the majority of the cases, the 1st DMTA arose as the continuation of the DPA, while the rest were given off as branches from the AA. In relation to the dorsal interossei muscles, all of the the arteries were either within the muscle fibers (53%) or beneath them (47%), on the right side. On the left side, the 1st DMTA was above the muscles in 40% of the cases; within the muscles in 53%; and beneath the muscles in 7%. The 2nd and 3rd DMTAs were above the muscles in 57% and in 53% of the cases, respectively. Conclusion These results reveal that the DMTAs show variation in their origin and position relative to the dorsal interossei muscles. These variations display bilateral asymmetry.

P32-S Application of decomposition based quantitative EMG (DQEMG) to focal neuropathies

Background EMG signals can be decomposed into their constituent motor unit potential trains and further analyzed using specific signal processing algorithms which provide novel and useful information regarding the temporal and electrophysiological behaviour and morphological attributes of motor units. In low to moderate stages of focal neuropathies (when only focal demyelination or low axonal sensory affection is registered) traditional needle EMG evaluation is usually normal. However, DQEMG provides evidence of motor unit instability in a significant portion of otherwise normal muscles. Material and methods 20 case and 9 control subjects were studied with median and ulnar ENG, quantitative EMG and DQEMG (abductor pollicis brevis, first dorsal interosseus or abductor digiti minimi). Patients with symptoms suggesting focal median or ulnar neuropathies were selected as cases, except for those showing low-median compound muscle action potential amplitudes or needle EMG abnormalities. Control subjects were included when no ENG nor needle EMG abnormalities findings were encountered. Results 75% of cases with any focal demyelinating finding showed instability features in DQEMG, which were also found in 43% of the normal ENG and control groups. Applying more restrictive DQEMG criteria, instability was found in 63% of cases with focal ENG alterations and 43% with normal ENG, while the control group showed no abnormalities. Conclusions Decomposition-based quantitative EMG is a novel and more powerful tool for detecting abnormalities in motor unit potentials, compared with the classical quantitative or semi-quantitative needle EMG analysis.

P68-S The effect of compression on peripheral nerves in ALS patients

Background Compression over a peripheral nerve leads to several changes in structural and physiological properties of that nerve. Paranodal myelin abnormalities and impaired axonal transport are some pathological incidents defined after acute compression. Materials and methods In sixteen ALS patients and 16 controls, CMAP Scan curves were recorded from first dorsal interosseus (FDI) muscle by stimulating ulnar nerve at elbow before compression, compression in 5 consecutive CMAP scanning cycles, and after compression. Stimulus intensities needed to elicit 10% and 90% of CMAP and step number and step% were calculated for each scan. As a further comparison, areas under CMAP scan curves were examined using natural values, percentages, and differences between compression (comp) cycles. Results For both patients and controls, conventional CMAP scan parameters were not significantly different in consecutive cycles. During compression, a tendency of reduction in area under CMAP scan curve of ALS patients (164.8 mVms, 156.3 mVms, 146.5 mVms, 142.1 mVms, 142.7 mVms, 137 mVms, and 174.9 mVms for pre-comp, 1st comp, 2nd comp, 3rd comp, 4th comp, 5th comp, and post- comp cycles, respectively) and a tendency of increase in CMAP scan curve area of healthy subjects (283.3 mVms, 315.6 mVms, 298.5 mVms, 319.7 mVms, 336.1 mVms, 361.4 and 308.1 mVms for pre-comp, 1st comp, 2nd comp, 3rd comp, 4th comp,5th comp, and post- comp cycles, respectively) were observed. Conclusions Probably due to incidental changes in nerve excitability, ALS patients mostly reacted differently to nerve compression when compared with healthy subjects.

P40-F The relationship between age and SICI parameters obtained with threshold tracking TMS

Background Recently developed threshold tracking TMS (TT-TMS) paired pulse techniques have been shown to be of benefit in clinical diagnostic practice. Reduced Short Interval Cortical Inhibition (SICI) with increasing age has been shown in several studies using conventional paired-pulse TMS techniques. However, TT-TMS SICI parameters did not correlate to age in healthy subjects in a previous study (Shibuya et al., 2016). We aimed in this study to present the preliminary results of our normal material on TT-SICI and the relationship between SICI measurements and age. Material and methods Thirty-three healthy subjects (mean age: 51.06 ± 2.48, range: 23–77) were included. Paired-pulse TT-TMS was undertaken using a 90 mm figure-of-eight coil applied to the motor cortex, with currents generated by BiStim system controlled by Qtrac software. The motor evoked potential (MEP) response was recorded over the first dorsal interosseus (FDI). MEP amplitude was set to a target value of 0.2 mV, and the changes in the intensity of the test stimulus required to generate this target MEP were measured. The relationship between age and SICI measurements were analyzed using regression analysis. Results Resting motor threshold (RMT) (MSO, %) (mean: 54.43 ± 2.41) and SICI (%) at 1 ms (12.01 ± 1.86), 2.5 ms (11.02 ± 1.65), 3 ms (8.20 ± 1.69) and 1–7 ms (5.93 ± 1.12) on TT-TMS were analysed. RMT increased with increasing age (r = 0.45, p = 0.08), while age had an inverse relationship with SICI on 1 ms (r = −0.49, p = 0.003), 2.5 ms (r = −0.45, p = 0.008), 3 ms (r = −0.41, p = 0.019) and 1–7 ms (r = −0.41, p = 0.017). Conclusions SICI parameters closely relate to age for TT-TMS similar to previously reported conventional. Further studies are required with large groups of healthy subjects.

P67-S Fasciculation potentials in ALS: Surface or needle recording?

Background Fasciculation potentials (FPs) are indicators for ongoing denervation-reinnervation in ALS not only by relying on their presence but also their configuration and firing characteristics. Present study is aimed to record FPs in ALS patients by using both surface and needle electrodes and to question the value of surface recording. Material and methods Nineteen definitive ALS patients were enrolled. Surface and needle recordings were done in first dorsal interosseus muscle. Needle recordings were done at 3 different positions. Activity was acquired for 2 min and stored for each recording. Quantitative MUP analysis was performed. MUP indices were calculated. The frequency of FPs in surface and needle recordings was compared. FPs and MUPs re-analyzed off-line to search whether the fasciculating motor unit voluntarily recruits. Results Needle recording revealed significantly high numbers of FPs. Numbers of FPs recorded from patients were ranged between 7 and 123 for surface recording (mean 36.7 ± 34) and 14–313 for needle recording (mean 109 ± 83.4) at three recording sites. However, surface recording revealed more FPs if comparison was done with the needle location where the least number of FPs was encountered. Interestingly most of the needle-recorded FPs was not among the MUPs that quantitatively analyzed. Surface recording was suitable for recognizing combined FPs but needle recording was much better in detecting complex FPs. Moreover, needle recording enabled examiner to trace whether fasciculating motor unit recruits voluntarily. Conclusions Surface recording of FPs is a quick and painless way to detect FPs for superficial muscles. Needle recording yields more detailed information about FPs.

An acute application of transcranial random noise stimulation does not enhance motor skill acquisition or retention in a golf putting task

Transcranial random noise stimulation (tRNS) is a brain stimulation technique that has been shown to increase motor performance in simple motor tasks. The purpose was to determine the influence of tRNS on motor skill acquisition and retention in a complex golf putting task. Thirty-four young adults were randomly assigned to a tRNS group or a SHAM stimulation group. Each subject completed a practice session followed by a retention session. In the practice session, subjects performed golf putting trials in a baseline test block, four practice blocks, and a post test block. Twenty-four hours later subjects completed the retention test block. The golf putting task involved performing putts to a small target located 3 m away. tRNS or SHAM was applied during the practice blocks concurrently with the golf putting task. tRNS was applied over the first dorsal interosseus muscle representation area of the motor cortex for 20 min at a current strength of 2 mA. Endpoint error and endpoint variance were reduced across the both the practice blocks and the test blocks, but these reductions were not different between groups. These findings suggest that an acute application of tRNS failed to enhance skill acquisition or retention in a golf putting task.

Is there a relationship between the occurrence of frenular ligaments and the type of fibularis longus tendon insertion?

PurposeThe fibularis longus muscle (FLM) is located in the lateral compartment of the leg. Although the FLM presents high morphological variability, particularly the tendon, little is known of its insertion. Similarly, little information exists regarding the great diversity of the Frenular ligament. The main aim of the study was hence to characterize the morphology of the fibularis longus tendon (FLT) and its accessory bands, to classify it and to determine the incidence of frenular ligaments. I hypothesize that the presence of anterior/posterior frenular ligament can be closely correlated with a given type of fibularis longus tendon insertion. MethodsClassical anatomical dissection was performed on 100 lower limbs (50 female, 50 male) fixed in 10% formalin solution. The morphology of the insertion of the FLT and of the frenular ligaments was evaluated. ResultsThe FLM was present in all specimens. Three types of insertion were observed, the most common being Type I (49%): a single distal attachment in which the tendon inserts into the lateral tubercle of the base of the I metatarsal bone. The second most common type was Type II (40%): bifurcated distal attachment, the main tendon inserts into the lateral tubercle of the base of the I metatarsal bone. This group was divided into three subtypes (A–C), subtype (A) — the accessory band inserts into the medial cuneiform bone; subtype (B) — a strong, accessory band inserts into both the base of the I metatarsal bone and the medial cuneiform bone, including the first metatarsal-cuneiform joint; subtype (C) — the accessory band inserts into the first interosseus dorsalis muscle. The rarest type was Type III (9%), characterized by a single distal tendon, which fuses with other adjacent muscle tendons before insertion. The main tendon inserts into the lateral tubercle of the base of the I metatarsal bone; this group was divided into two subtypes (IIIA – fusion with the tibialis posterior tendon and IIIB – fusion with the adductor hallucis longus). The anterior frenular ligament was present in 49% of specimens, whereas the posterior frenular ligament joined the FLT to the long calcaneo-cuboid ligament and was present in 9%. ConclusionBoth the fibularis longus tendon and frenular ligament present high morphological variability. The anterior frenular ligament is closely correlated with Type I of the proposed classification, while the posterior frenular ligament is associated with Type II b. Knowledge of particular types of insertion is essential for both clinicians and anatomists. Level of evidence– II basic science research.

Age-related changes in TMS-based gamma-aminobutyric acid (GABA) modulation during a unimanual simple and choice reaction time task.

Age-related changes in TMS-based gamma-aminobutyric acid (GABA) modulation during a unimanual simple and choice reaction time task.

Are age-related changes in cortical motor representations linked with facilitation/inhibition in the primary motor cortex?

Are age-related changes in cortical motor representations linked with facilitation/inhibition in the primary motor cortex?

First dorsal metacarpal artery flap a workhorse for reconstruction of selected small defects of the hand

Background: The first dorsal metacarpal artery (FDMA) flap is used mainly for reconstruction of thumb defects. We share our experience of this flap for various defects of thumb and also its use to cover other defects. Materials and Methods: Case records of 15 patients with FDMA flap between October 2015 and February 2018 at our center were analyzed retrospectively. Data were analyzed for etiology, associated comorbidities, interval between injury and operation, site of defect, harvesting technique, and inclusion of dorsal interossei muscle cuff, complications, donor-site morbidities, and postoperative sensory recovery. Results: Of 15 patients, 13 were male and 2 were female. Eleven patients had a posttraumatic defect, 2 had post-electric burn defect, 1 had a firecracker injury, and 1 had a post snakebite defect. Of 15 patients, 12 patients had thumb defects, 1 patient with defect of first web space, 1 on volar aspect of palm, and 1 on the dorsum of hand over the head of third metacarpal. All patients showed protective sensations and 6 patients with 12-month follow-up showed minimum of 9 mm of two-point discrimination with no donor-site morbidity. Conclusions: The FDMA flap has a constant anatomy, easy dissection, and shows good functional and esthetic results. FDMA flap is the first treatment of choice for defects of the thumb, but it can be used for selected small defects of hand due to its wide arc of rotation.