Flexor Digitorum Profundus Research Articles

Transcriptome profiling of digital flexor tendons after injury in a chicken model.

Background: Modulation of tendon healing remains a challenge because of our limited understanding of the tendon repair process. Therefore, we performed the present study to provide a global perspective of the gene expression profiles of tendons after injury and identify the molecular signals driving the tendon repair process.Results: The gene expression profiles of flexor digitorum profundus tendons in a chicken model were assayed on day 3, weeks 1, 2, 4, and 6 after injury using the Affymetrix microarray system. Principal component analysis (PCA) and hierarchical cluster analysis of the differentially expressed genes showed three distinct clusters corresponding to different phases of the tendon healing period. Gene ontology (GO) analysis identified regulation of cell proliferation and cell adhesion as the most enriched biological processes. Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis revealed that the cytokine–cytokine receptor interaction and extracellular matrix (ECM)–receptor interaction pathways were the most impacted. Weighted gene co-expression network analysis (WGCNA) demonstrated four distinct patterns of gene expressions during tendon healing. Cell adhesion and ECM activities were mainly associated with genes with drastic increase in expression 6 weeks after injury. The protein–protein interaction (PPI) networks were constructed to identify the key signaling pathways and hub genes involved.Conclusions: The comprehensive analysis of the biological functions and interactions of the genes differentially expressed during tendon healing provides a valuable resource to understand the molecular mechanisms underlying tendon healing and to predict regulatory targets for the genetic engineering of tendon repair.Tendon healing, Adhesion, Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, Weighted Gene Co-expression Network Analysis, Protein–protein Interaction

Treatment of tendinous mallet finger deformity with a part of the flexor digitorum profundus tendon.

To introduce and evaluate an updated surgical technique for the treatment of tendinous mallet finger deformity. From April 2017 to September 2018, 13 cases of tendinous mallet finger deformity were treated. All patients had zone I extensor tendon rupture, with no residual tendon at the insertion for suture, and no avulsion fracture in the distal phalanx. Extensor tendon insertion reconstruction was realized by suturing the transferred portion of the flexor digitorum profundus tendon with the proximal end of the extensor tendon via a constructed bone tunnel. The treatment efficacy of the enrolled patients was evaluated by using Dargan evaluation criteria post-operatively. All patients were followed up with an average duration of 10.6 months. At the last follow-up, 12 patients showed excellent function recovery and one case had unsatisfactory outcome according to the Dargan evaluation criteria. Satisfactory therapeutic outcome for the treatment of tendinous mallet finger deformity can be achieved by reconstructing extensor tendon insertion using a part of the flexor digitorum profundus tendon, implying that the proposed treatment method is worthy of clinical application.

Ultrasound-Guided Non-radio Opaque Symptomatic Foreign Body Removal

This is a case of a 20-year-old lady presenting in surgical OPD with history of trauma 1 year ago with foreign body in situ in the right distal forearm where she had history of unsuccessful attempt of surgery for foreign body removal at the time of injury. She was investigated with ultrasonography of local part which suggested thorn within the tendon of flexor group of muscles. Thorn removal was performed with ultrasonography guidance under brachial block. Thorn was found to be completely within the tendon of flexor digitorum profundus with close vicinity to ulnar artery. The surgery was performed on day-care basis without intraoperative or postoperative complication, and she was discharged with utmost satisfaction on the same evening.

Outcomes After Flexor Tendon Injuries in the Pediatric Population: A 10-Year Retrospective Review.

Background: Pediatric outcomes after flexor tendon repairs are variable, and evidence in the literature remains scarce. Methods: Repair of pediatric flexor tendon injuries was reviewed over a 10-year period (2005-2015). Data collection consisted of patient demographics, injury characteristics, anesthetic choice, repair technique, rehabilitation protocol, American Society for Surgery of the Hand Total Active Motion (TAM) scores, and complications. Results: There were 109 patients included in our study, with a total of 162 digits injured and 235 flexor tendon injuries. The mean age was 12 ± 4.6 years. The small finger (48 of 162; 30%) and the flexor digitorum profundus tendon (126 of 235) were the most commonly injured. The mechanism of injury was mainly from a knife (46 of 109; 42.2%) in zone II (82 of 159; 52%). Injuries were mostly repaired under general anesthetic (61 of 104; 56%). The Kessler technique was the predominant repair mechanism (111 of 225 repairs; 49%). Most patients (103 of 109; 95%) had excellent or good TAM scores with 5 postoperative ruptures reported. The most common complication was stiffness (17 of 121 complications; 14%), with most patients having no complications ( 74 of 109 patients; 68%). Patients were commonly immobilized (mean 8.4 ± 10.3 weeks) with a splint (93 of 109; 85%). There were 85 patients who followed a postoperative rehabilitation protocol for 12 ± 18 weeks. Patient demographics, time of repair, injury characteristics, anesthetic choice, and rehabilitation protocol were not significantly correlated with TAM scores or complication rates. Conclusions: Pediatric tendon injuries have good outcomes with no predictive factors identified. Surgical repairs performed under local anesthetic have similar outcomes without increased rates of complications, but remain underused in the pediatric population.

Zone 2 Flexor Tendon Repair Location and Risk of Catching on the A2 Pulley

To determine the region of the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) tendons in zone 2 that, when involved by a laceration repair, will reliably catch on the A2 pulley after surgery. Using fresh-frozen cadavers (5 hands, 20 digits), excursions of the FDP and FDS tendons were measured in relation to the A2 pulley. The C1, A3, and C2 pulleys were resected. The digit was maximally flexed by applying traction to the flexor tendon in the forearm. An 8-0 suture tag was placed in the flexor tendons immediately distal to the A2 pulley. The digit was then passively fully extended to measure tendon excursion. Measurements were repeated with 50% venting and 100% release of the A4 pulley. Reference points such as tendon insertions and flexion creases were obtained. This protocol was repeated sequentially for the index, middle, ring, and little fingers. For all 20 fingers, the suture placed into the FDP just distal to the A2 pulley with the finger fully flexed traveled 1.6 ± 1.9 mm distal to the proximal edge of the A4 pulley with passive extension of the finger. The mean excursion for the FDP was 24.6 ± 3.2 mm, and 16.9 ± 3.1 mm for the FDS. The mean A2 pulley length was 16.2 ± 3.5 mm, and the mean distance between the distal edge of the A2 pulley and the proximal edge of the A4 pulley was 23.0 ± 3.3 mm. Venting the A4 pulley 50% and 100% increased FDP excursion a maximum of 0.9 and 1.9 mm, respectively. An FDP repair proximal to the A4 pulley will slide under the A2 pulley with full active digital flexion after surgery. If the distal FDP stump lies underneath the A4 pulley with the digit fully extended, the FDP repair will not likely engage the A2 pulley with full flexion after surgery. The FDP excursion can be reliably predicted as a percentage of the A2 (distal) to the A4 (distal) pulley distance. Most importantly, the distance between the repair site and the A4 pulley approximately equals the length of the A2 pulley that requires release to avoid postoperative triggering. Knowledge of this high-risk region of flexor tendon repair will guide surgeons regarding the potential need for partial release of the A2 pulley.

Assessment of fixation for anterior cruciate ligament reconstruction using oversized suspensory devices on full-length femoral tunnels

BackgroundIn ACL repair, full-length single-diameter tunnels facilitate anatomic femoral fixation with suspensory devices, especially with outside-in techniques, and are required after accidental cortical perforation. With tunnel diameters over 6 mm, fixation resistance using regular suspensory devices may not suffice. Oversized cortical footprint devices could be a solution to guarantee fixation performance in larger tunnel diameters. This study aims to assess the biomechanical properties of ACL femoral fixation provided by two enlarged suspensory devices of similar characteristics, a fixed loop (G-Lok™ with G-Lok-XL™) and an adjustable loop (ProCinch™ with G-Lok-XL™), resting on a full-length 9 mm diameter tunnel compared to the widely accepted regular fixed-loop device (G-Lok™) on a socket tunnel. MethodsTwenty-seven fresh frozen porcine femurs and flexor digitorum profundus tendons were randomly assigned to a study group depending on the fixation method used (N = 9). Graft-femur constructs were subjected to a traction cyclic test (5000 cycles, [50–250]N load, 1 Hz) followed by a load-to-failure test (v = 1 mm/s). Residual displacement during the cyclic test and stiffness, displacements at physiological loads, ultimate load and corresponding displacement during the load-to-failure test were determined. FindingsNo significant differences could be established for any parameter measured in the comparison between the control with the socket tunnel and the oversized fixations with full-length tunnels. InterpretationACL femoral fixation achieved in full-length single diameter tunnels by using an enlarged suspension device, both with a fixed or an adjustable loop, provide similar biomechanical properties to the gold-standard fixed-loop device in a socket tunnel. Therefore, its clinical use may be safe.

Flexor Tendon Grafting Using Extrasynovial Tendons Followed by Early Active Mobilization

PurposeThis study evaluated the outcomes of early active mobilization after flexor tendon grafts using extrasynovial tendons with a novel distal fixation technique.MethodsThis study was a retrospective case series. The flexor digitorum profundus (FDP) tendons of 7 digits in 7 patients were reconstructed with extrasynovial tendons, which included the palmaris longs, plantaris, and extensor digitorum longus, in a single- or 2-stage procedure between 2008 and 2017. Of the 7 patients, 6 were male and the average patient age was 48 years. The injuries involved 2 middle, 2 ring, and 3 little fingers. The tendons were sutured into the appropriate FDP tendon proximally using end-weave anastomosis; the distal end of the graft was fixed to the distal stump of the FDP using an interlacing suture or a small bone anchor combined with the pull-through technique. The digits were mobilized with a combination of active extension and passive and active flexion in a protective orthosis during the first 6 weeks after surgery. Average follow-up was 18 months. We measured active and passive digit motion both before tendon grafting and at the final evaluation. Outcomes were graded by the LaSalle formula to assess staged flexor tendon reconstruction.ResultsAverage passive range of motion (ROM) of the proximal and distal interphalangeal joints before flexor tendon grafting was 146° (SD, 22°). Mean active ROM of these joints at the final evaluation was 123° (SD, 34°). Using the LaSalle formula, mean recovery of active motion was 83%. We encountered no grafted tendon rupture and no finger required tenolysis.ConclusionsOur proximal and distal fixation techniques allowed the autologous extrasynovial tendon grafts to withstand the stress encountered during early active mobilization with good postoperative ROM and minimal complications.Type of study/level of evidenceTherapeutic I.

Atypical osteochondroma of the hamate that presented clinically as carpal tunnel syndrome: report of an extremely rare case and literature review

BackgroundOsteochondroma is a benign tumor that occurs mainly at the metaphysis of long bones and seldom arises from carpal bones. We describe an extremely rare case of osteochondroma of the hamate without a typical cartilaginous cap and with a spiky bony protrusion in an elderly patient.Case presentationA 78-year-old right-handed female housekeeper had a multilobed osteochondroma of the hamate, which caused carpal tunnel syndrome and irritation of the flexor tendons. Radiological examinations showed a morphological abnormality of the hamate comprising a spiky bony protrusion into the carpal tunnel and a free body proximal to the pisiform. Open carpal tunnel release and resection of the spiky bony protrusion on the hook of the hamate were performed. The flexor digitorum profundus tendons of the ring and little fingers displayed synovitis and partial laceration in the carpal tunnel. Histological examination also showed atypical findings: only a few regions of cartilaginous tissue were seen in the spiky bony protrusion, whereas the free body proximal to the pisiform contained thick cartilaginous tissue such as a cartilaginous cap typical of osteochondroma. We speculated that the bony protrusion to the carpal tunnel had been eroded by mechanical irritation caused by gliding of the flexor tendon and had resulted in the protruding spiky shape with less cartilaginous tissue. The fractured cartilaginous cap had moved into the cavity within the carpal tunnel proximal to the pisiform and had become a large free body.ConclusionsOsteochondroma of the carpal bone may take various shapes because the carpal bone is surrounded by neighboring bones and tight ligaments, which can restrict tumor growth. This type of tumor is likely to present with various symptoms because of the close proximity of important structures including nerves, tendons, and joints. The diagnosis of osteochondroma of the carpal bone may be difficult because of its rarity and atypical radiological and histological findings, such as the lack of a round cartilaginous cap. We suggest that surgeons should have a detailed understanding of this condition and should make a definitive diagnosis based on the overall findings.

Ultrasound can differentiate inclusion body myositis from disease mimics.

IntroductionThe diagnosis of inclusion body myositis (IBM) can be challenging, and its presentation can be confused with other forms of myositis or neuromuscular disorders. In this study we evaluate the ability of quantitative muscle ultrasound to differentiate between IBM and mimicking diseases.MethodsPatients 50 years of age and older were included from two specialty centers. Muscle echogenicity and muscle thickness of four characteristically involved muscles in IBM were measured and compared with polymyositis (PM)/dermatomyositis (DM), other neuromuscular disorders, and healthy controls.ResultsEchogenicity was higher and muscle thickness generally lower in all four muscles in IBM compared with PM/DM and normal controls. When comparing IBM with the comparator groups, the flexor digitorum profundus was the most discriminative muscle.DiscussionUltrasound appears to be a good test to differentiate established IBM from PM/DM and neuromuscular controls, with value as a diagnostic tool for IBM.

Biomechanical Analysis of Zone 2 Flexor Tendon Repair With a Coupler Device Versus Locking Cruciate Core Suture

To compare flexor tendon repair strength and speed between a tendon coupler and a standard-core suture in a cadaver model. In 5 matched-pair fresh cadaver hands, we cut the flexor digitorum profundus tendon of each finger in zone 2 and assigned 20 tendons to both the coupler and the suture groups. Coupler repair was with low-profile stainless steel staple plates in each tendon stump, bridged by polyethylene thread. Suture repair was performed using an 8-strand locking-cruciate technique with 4-0 looped, multifilament, polyamide suture. One surgeon with the Subspecialty Certificate in Surgery of the Hand performed all repairs. Via a load generator, each flexor digitorum profundus was loaded at 5 to 10 N and cycled through flexion just short of tip-to-palm and full extension at 0.2 Hz for 2,000 cycles to simulate 6 weeks of rehabilitation. We recorded repair gapping at predetermined cycle intervals. Our primary outcome was repair gapping at 2,000 cycles. Tendons that had not catastrophically failed by 2,000 cycles were loaded to failure on a servohydraulic frame at 1 mm/s. Tendon repair gapping was similar between coupled and sutured tendons at 2,000 cycles. Tendons repaired with the coupler had higher residual load to failure than sutured tendons. Mean coupler repair time was 4 times faster than suture repair. Zone 2 flexor repair with a coupler withstood simulated early active motion in fresh cadavers. Residual load to failure and repair speed were better with the coupler. This tendon coupler may eventually be an option for strong, reproducible, rapid flexor tendon repair.

Idiopathic Carpal Spasm (Trousseau’s Sign) After Intraoperative Arm Tourniquet Inflation in an Intubated Patient

We present a case of a 38-year-old male who sustained a laceration from a knife to the volar aspect of his left index and middle fingers. He had clinical injury to his flexor digitorum profundus tendons to both digits. He underwent operative exploration and repair of the tendons under general anaesthetic. An arm tourniquet was inflated to allow for haemostasis in the operative field. A few minutes after inflation, the patient’s hand went into carpal spasm. The tourniquet was deflated and the spasm resolved. Intraoperative serum calcium and carbon dioxide levels were normal. The operation proceeded with the tourniquet deflated. Postoperatively serum calcium and magnesium levels were within normal limits, as was serum vitamin D and parathyroid hormone levels. It has been reported that carpal spasm can occur with tourniquet use in the anxious patient due to hyperventilation and resultant metabolic alkalosis. This however is the first reported case of carpal spasm in the setting of tourniquet use and normal serum electrolytes and respiratory parameters in an intubated patient.

The Gantzer Muscle: An Expanded Study of this Variant Forearm Muscle

Gantzer muscles are anatomical variations found within the flexor compartment of the forearm. The Gantzer muscle typically arises from the flexor digitorum superficialis (FDS) and inserts into the flexor pollicis longus (FPL) or flexor digitorum profundus (FDP). The presence of this muscle can cause various compressive injuries, including neuropathy of the median or anterior interosseous nerve and impingement of the ulnar, common, or anterior interosseous arteries. Despite its high prevalence, the Gantzer muscle is often excluded from the differential for acute compartment syndrome and should be further considered during treatment and surgical management. This study expanded upon a previous assessment of cadaveric specimen forearms to determine further the prevalence of origin, insertion, and innervation of Gantzer muscles, as well as possible compressions induced from impingement by the anomalous muscle. A total of 288 limbs were dissected in 144 cadavers. The Gantzer muscle was found in 54.6% (148:271) of limbs. Therefore, in general, the Gantzer muscle is more likely to be present than absent. This report also details common and uncommon origins and insertions of Gantzer variants.Support or Funding InformationT. Walley Williams Summer Anatomy Research Fellowship; WV Research Challenge Fund [HEPC.dsr.17.06]

Intraspecific and intrafamilial variation in primate forearm muscle architecture

Recent studies have examined locomotion and postural correlates of primate forearm muscle architecture. However, these have done so using relatively small sample sizes – usually one or two specimens per species, and relatively few species per genus and family. Thus, little is known about intraspecific variation in forearm muscle fiber architecture in primates, and whether there are notable differences in these variables between closely related taxa. The current study addresses these deficits by assessing both qualitative (presence/absence of specific muscles) and quantitative (physiological cross‐sectional area [PCSA], fascicle length [FL] and muscle mass [MM]) differences in forearm muscle architecture of larger intraspecific and samples with greater coverage of specific primate families than had been included in previous work. Namely, we studied 30 callitrichid specimens from 11 species, 15 lemurid specimens from 7 species and 9 cebids from two species ‐ a total sample size of 54 specimens from 20 species. Within species, FL varied the greatest among architectural variables and MM varied the least. We also found that there is great variation in both the extent of separation and fusion of flexor digitorum superficialis and profundus, and in the extent of accessory extensors in most species of callitrichids and Saimiri, but no variation in the gross forearm muscle architecture within lemurids. More than a quarter of the callitrichid specimens had forearm muscle configurations that deviate from their standard published description, suggesting that blanket characterizations of anatomical configurations at the genus or family level may obscure potentially important intra‐ and inter‐specific trends.Support or Funding InformationNational Science Foundation: IOS‐15‐57125, BCS‐14‐40599

Morphological Changes in Flexor Tendon Adhesion Following Early Exercise After Tendon Repair.

Adhesion is a common complication following surgical repair of flexor tendons, resulting in the restriction of tendon gliding. We investigated the effect of early exercise on adhesion formation. To create an adhesion model, the proximal region of the second phalanx of the third toe in 4-month-old White Leghorn chickens was cut. The gliding side of the flexor digitorum profundus was hemiresected and the bony floor was crushed to enhance adhesion formation. The resected area was fixed in an extended position for 1, 2, or 3 weeks. Following 1, 2, or 3 weeks of active exercise, the chickens were sacrificed and morphological changes in the adhesions were assessed. In the 1- and 2-week fixed groups, 1, 2, or 3 weeks of active exercise resulted in mesotenon-like adhesion that was elastic and had no effect on tendon gliding. However, in the 3-week fixed group, a mature adhesion remained with limited change and tendon gliding was inhibited even after 3 weeks of active exercise. Thus, we concluded that adhesions become more elastic with early exercise within 2 weeks after tendon repair, but that adhesions following tendon repair tend not to show any further elastic changes when exercise is started 3 weeks after the repair.

Valgus stability is enhanced by flexor digitorum superficialis muscle contraction of the index and middle fingers

BackgroundFlexor digitorum superficialis (FDS) muscle provides dynamic stabilization and medial elbow support for ulnar collateral ligament (UCL). The FDS contraction significantly affects the medial joint distance (MJD) through grip contraction. However, it remains unclear whether FDS activity alone contributes to medial elbow stability, or together with the activation of the flexor digitorum profundus during grip contraction, and which finger’s FDS is the main contributor to elbow stability. We investigated the resistive effects of isolated FDS contraction in individual fingers against valgus stress in the elbow joint using stress ultrasonography (US).MethodsWe investigated 17 healthy males (mean age, 27 ± 5 years). Valgus stress US was performed using the Telos device, with the elbow at 30° flexion. MJD was measured for each arm during 3 separate conditions: at rest (unloaded), under valgus load (50 N) (loaded), and under valgus load with FDS contracted in individual fingers (loaded-contracted).ResultsMJD was significantly longer when loaded (5.4 ± 0.4 mm) than unloaded (4.1 ± 0.2 mm, P = 0.007) or loaded-contracted (4.6 ± 0.3 mm, P = 0.003) for each finger. When loaded-contracted, MJD differed statistically between the index and ring fingers (P = 0.03) and between the middle and ring fingers (P = 0.04). However, the difference between the index and middle fingers was not statistically significant (P = 0.08).ConclusionsIndividual FDS contraction, particularly of the index and middle fingers, contributes most to stabilization against valgus stress. Thus, injury care programs should incorporate FDS exercises of these fingers.

Brain source imaging based on movement-related cortical potentials induced by fatigue during self-paced handgrip contractions.

By using standard low resolution electromagnetic tomography (sLORETA), we sought to explore the changes in brain source localization when performing right handgrip contractions in the condition of muscular fatigue. Ten healthy adults volunteered for this study, and were asked to perform repeated and intermittent self-paced right handgrip contractions at 30% maximal voluntary contraction based on visual feedback leading to fatigue of right flexor digitorum profundus. Motor potentials from the movement-related cortical potentials were extracted from the electroencephalogram and were further analyzed by sLORETA. The activated cortical regions were mainly the Brodmann area 6 on the superior frontal and medial frontal gyri, and the BA 10 on the frontal and medial frontal gyri. With the development of muscular fatigue, current density of the motor potential significantly increased and the activated cortical areas markedly enlarged. In an attempt to maintain a target level of force during upper limb muscle fatigue induced by low intensity repetitive activation, the brain enhances the activation of sensorimotor cortex and enlarges the sensorimotor cortex area, especially in the ipsilateral hemisphere.

Mini-Plate and Screw Fixation Technique for Comminuted Flexor Digitorum Profundus Avulsion Fracture

Avulsion fracture of flexor digitorum profundus (FDP) tendon is relatively rare fracture at the distal phalangeal base than avulsion fracture of terminal extensor tendon. Terminal extensor avulsion fracture, known as bony mallet finger, could be successfully treated by closed reduction and pinning, such as extension block technique. However, most of FDP avulsion fracture, known as Jersey’s finger, needed open reduction, because of the proximal migration of fracture fragment and difficulty of pin fixation. Up to date, most of FDP avulsion fractures were treated by open reduction and fixation by pull-out suture or suture anchor technique. We report a case of comminuted FDP avulsion fracture, successfully treated by open reduction and mini-plate and screw fixation technique.

In Reply: Surgical Treatment of Intraneural Ganglion Cysts of the Ulnar Nerve at the Elbow: Long-Term Follow-up of 9 Cases.

Background Intraneural ganglion (IG) cysts have been considered curiosities and their pathogenesis remains controversial. Objective To clarify ulnar nerve at the elbow (UNE) pathogenesis and long-term surgical outcomes by presenting 9 rare cases of IG of the UNE. Methods Surgical treatment of IG was performed. Clinical symptoms, physical examinations, and electromyogram were evaluated pre- and postoperatively. At least 4 yr of follow-up was performed. Results The Tinel's sign became negative and local elbow pain disappeared in all 9 patients after surgery, and the average visual analog scale/score dropped from 4.9 (3-8) to 0 (0-0) after 6.2 d (2-10) on average. Two patients retained positive Froment test, "claw hand" and paresthesias with the 2-point discrimination much different from the contralateral little finger. Postoperative the UK Medical Research Council muscle strength score (MRC) grades of the flexor carpi ulnaris and the flexor digitorum profundus muscle of the fourth and fifth digits recovered to M4-M5 from M0-M2 in all 9 patients. The postoperative MRC grades of the third to fourth lumbrical muscles, the interossei, and the hypothenar recovered to M3-M5 from M0-M2 in 7 patients. Cystic articular branch (CAB) was found in all 9 patients intraoperatively. No symptomatic recurrence of IG was seen. The mean motor nerve conduction velocity of ulnar nerve across the elbow recovered from 5.3 to 41.2 m/s. Conclusion A unifying articular theory is responsible for the pathogenesis of IG of UNE and disconnection of the CAB would prevent recurrence. The long-term outcome is good after surgical treatment of IG of UNE.

The immediate effect of whole body vibration training on the electromyographic activity of contralateral hand muscles; a randomized controlled trial

Whole Body Vibration (WBV) has been used as a useful adjunct to improve the neuromuscular function of the upper limb. Cross-transfer of strength plays an important role in rehabilitation of unilateral injuries. The present research intended to evaluate the acute effect of low frequency WBV training on cross-transfer of electromyographic activity and hand muscles strength when the measurement was performed on the contralateral limb. This was a randomized crossover trial conducted in a clinical biomechanics laboratory. Twenty-eight healthy participants aging between 20 and 35 years were included who were involved in two sessions with two weeks of rest. The participants were randomly assigned in two groups as follows: 1) active WBV/sham WBV; 2) sham WBV/active WBV. The participants were asked to stand on the vibrating plate and pull its belt in a vibrating mode using their dominant hand. Then, after a two-week rest, they performed the same task in the vibrating mode (35 Hz). Grip strength and electromyography (root mean square) in flexor digitorum profundus (FDP), flexor digitorum superficialis (FDS), extensor carpi radialis (ECR), and extensor carpi ulnaris (ECU) muscles of the contralateral limb were measured before and after exercise in both phases. No significant change was observed in the electrical activity of FDP, FDS, ECR, ECU muscles, and hands' grip strength of the contralateral limb (P > 0.05). WBV (35 Hz) was not able to augment cross-transfer in electromyographic activity and neuromuscular performance of the upper limb. Further studies would help to explore these results for several sessions of WBV on cross-transfer of training.

Are There Trigger Points in the Spastic Muscles? Electromyographical Evidence of Dry Needling Effects on Spastic Finger Flexors in Chronic Stroke.

The purpose was to examine the immediate effects of dry needling to spastic finger muscles in chronic stroke. Ten chronic stroke patients with spasticity in finger flexors participated in this experiment. Dry needling to the flexor digitorum superficialis (FDS) muscle was performed under ultrasound guidance for about 30 s (about 100 times). Clinical assessment and intramuscular needle EMG readings were made before and immediately after dry needling. Immediately after needling, the FDS muscle was felt less tight to palpation and the proximal phalangeal joint rested in a less flexed position (p = 0.036). The MAS score decreased for FDS (p = 0.017) and flexor digitorum profundus (FDP) (p = 0.029). Motor unit action potential (MUAP) spikes decreased from 41.6 ± 5.5 to 6.7 ± 2.2 spikes/s (p = 0.002), an 84% reduction after dry needling. However, the pre-needling spike frequency was not correlated to MAS or resting position of the FDS muscles. Dry needling to the spastic finger flexors leads to immediate spasticity reduction, increased active range of motion, and decreased frequency of motor unit spontaneous firing spikes. The results suggest that latent trigger points possibly exist in spastic muscles and they contribute partly to spastic hypertonia of finger flexors in chronic stroke.