Flexor Digitorum Profundus Research Articles

Tension Reducing Muscle Stretch Protocol to Obtain Full Distal Tendon Excursion: A New Rehabilitation Protocol after Flexor Tendon Repair.

Background: Flexor tendon rehabilitation protocols minimize repair tension by limiting range of movement to prevent tendon rupture. The resultant muscle contracture inhibits finger extension, increases resistance in tendon gliding distally, and progress to proximal interphalangeal (PIP) joint flexion contracture. This study describes our new rehabilitation protocol, the Tension Reducing Muscle Stretch (TRMS), designed to prevent flexor muscle contracture and obtain full distal tendon excursion. Methods: We reviewed retrospectively 14 fingers in 13 consecutive patients with primary repair of complete zone I or II flexor digitorum profundus (FDP) tendon rupture were treated with our protocol between 2007 and 2019. Our rehabilitation following FDP 4-strand repairs consisted of three steps. The first step comprised of exercises from traditional protocols such as Duran, Kleinert, Synergistic-wrist-motion, and Place-and-hold. The second step comprised the TRMS exercise to prevent the onset of muscle contracture. Anatomically, FDP tendons arise from the same FDP muscle belly. TRMS involved placing the affected finger in full passive flexion while unaffected fingers were passively extended to full extension. This made the affected FDP muscle stretched. The final step incorporated the early active flexion motion exercise, in which simple fisting was performed, from a fully extended position. Results: The mean total active motion at the final follow up was 235° (range 170-265). Using the Strickland criteria, eight achieved excellent, four had good, two had fair results. The mean angle of passive extension deficit at the PIP joint at four weeks after surgery was -7° (-30-0), and at the final follow up was -3° (-20-0). No tendon repair was ruptured. Conclusions: This protocol reduced tension in the affected tendon muscle and encouraged tendon excursion distal to the repair site without complications. It allows full tendon excursion and prevents PIP joint contractures.

An Analysis of Profundus Tendon Repairs After Distal Phalanx Amputation in a Cadaveric Model of Little Finger Superficialis Deficiency

The flexor digitorum superficialis tendon to the little finger (FDS-5) has been observed to have a higher degree of functional and structural variation than the FDS of other digits. FDS-5-deficient individuals necessarily rely on the flexor digitorum profundus tendon to the little finger (FDP-5) for flexion in their little fingers. FDS-5 deficient patients who experience a considerable injury to their FDP-5 are therefore at a risk of losing substantial little finger flexion. The purpose of this study was to evaluate the degree of flexion of the little finger at the metacarpophalangeal and proximal interphalangeal (PIP) joints in a cadaveric model of FDS-5 deficiency following amputation of the distal phalanx. Ten fresh-frozen cadaveric upper extremities with no prior trauma were used. Loads were applied to the FDP-5. Flexion at the PIP and metacarpophalangeal joints was measured in degrees with a goniometer. Little finger flexion testing was conducted under 5 different conditions: "baseline," "FDS-deficient," "no repair," "bone anchor" repair, and "A4 pulley" repair. The results were as follows: (1) no significant differences in the flexion between baseline and FDS-deficient conditions; (2) a significant decline in PIP flexion in the no repair condition after FDP-5 division compared with the FDS-deficient condition; (3) a significant restoration in PIP flexion in both surgical repair groups compared with the no repair group; and (4) no significant differences in PIP flexion between the A4 pulley and bone anchor groups. The bone anchor repair and the A4 pulley repair demonstrate similar abilities to restore flexion of the little finger at the PIP joint to baseline levels in this cadaveric model. A clinical protocol is yet to be established for the surgical treatment in FDS-5-deficient patients requiring amputation of the distal phalanx of the little finger. This study aims to address this area of uncertainty by comparing the little finger flexion after 2 different approaches to profundus tendon reattachment that may be applicable in this clinical scenario.

Patterns of median nerve branching in the cubital fossa: implications for nerve transfers to restore motor function in a paralyzed upper limb.

The purpose of this study was to describe the anatomy of donor and recipient median nerve motor branches for nerve transfer surgery within the cubital fossa. Bilateral upper limbs of 10 fresh cadavers were dissected after dyed latex was injected into the axillary artery. In the cubital fossa, the first branch was always the proximal branch of the pronator teres (PPT), whereas the last one was the anterior interosseous nerve (AIN) and the distal motor branch of the flexor digitorum superficialis (DFDS) on a consistent basis. The PT muscle was also innervated by a distal branch (DPT), which emerged from the anterior side of the median nerve and provided innervation to its deep head. The palmaris longus (PL) motor branch was always the second branch after the PPT, emerging as a single branch together with the flexor carpi radialis (FCR) or the proximal branch of the flexor digitorum superficialis. The FCR motor branch was prone to variations. It originated proximally with the PL branch (35%) or distally with the AIN (35%), and less frequently from the DPT. In 40% of dissections, the FDS was innervated by a single branch (i.e., the DFDS) originating close to the AIN. In 60% of cases, a proximal branch originated together with the PL or FCR. The AIN emerged from the posterior side of the median nerve and had a diameter of 2.3 mm, twice that of other branches. When dissections were performed between the PT and FCR muscles at the FDS arcade, we observed the AIN lying lateral and the DFDS medial to the median nerve. After crossing the FDS arcade, the AIN divided into: 1) a lateral branch to the flexor pollicis longus (FPL), which bifurcated to reach the anterior and posterior surfaces of the FPL; 2) a medial branch, which bifurcated to reach the flexor digitorum profundus (FDP); and 3) a long middle branch to the pronator quadratus. The average numbers of myelinated fibers within each median nerve branch were as follows (values expressed as the mean ± SD): PPT 646 ± 249; DPT 599 ± 150; PL 259 ± 105; FCR 541 ± 199; proximal FDS 435 ± 158; DFDS 376 ± 150; FPL 480 ± 309; first branch to the FDP 397 ± 12; and second branch to the FDP 369 ± 33. The median nerve's branching pattern in the cubital fossa is predictable. The most important variation involves the FCR motor branch. These anatomical findings aid during nerve transfer surgery to restore function when paralysis results from injury to the radial or median nerves, brachial plexus, or spinal cord.

Muscle Selection and Dosing in a Phase 3, Pivotal Study of AbobotulinumtoxinA Injection in Upper Limb Muscles in Children With Cerebral Palsy.

Background: Guidelines recommend botulinum toxin-A in pediatric upper limb spasticity as part of routine practice. Appropriate dosing is a prerequisite for treatment success and it is important that injectors have an understanding on how to tailor dosing within a safe and effective range. We report upper limb dosing data from a phase 3 study of abobotulinumtoxinA injections in children with cerebral palsy.Methods: This was a double-blind, repeat-treatment study (NCT02106351). In Cycle 1, children were randomized to abobotulinumtoxinA at 2 U/kg control dose or clinically relevant 8 U/kg or 16 U/kg doses. Doses were divided between the primary target muscle group (PTMG, wrist or elbow flexors) and additional muscles tailored to clinical presentation. During Cycles 2–4, children received doses of 8 U/kg or 16 U/kg and investigators could change the PTMG and other muscles to be injected. Injection of muscles in the other upper limb and lower limbs was also permitted in cycles 2–4, with the total body dose not to exceed 30 U/kg or 1,000 U (whichever was lower) in the case of upper and lower limb treatment.Results: 212 children were randomized, of which 210 received ≥1 abobotulinumtoxinA injection. Per protocol, the elbow and wrist flexors were the most commonly injected upper limb muscles. Across all 4 cycles, the brachialis was injected in 89.5% of children (dose range 0.8–6 U/kg), the brachioradialis in 83.8% (0.4–3 U/kg), the flexor carpi ulnaris in 82.4% (0.5–3 U/kg) and the flexor carpi radialis in 79.5% (0.5–4 U/kg). Other frequently injected upper limb muscles were the pronator teres(70.0%, 0.3–3 U/kg). adductor pollicis (54.3%, 0.3-1 U/kg), pronator quadratus (44.8%, 0.1–2 U/kg), flexor digitorum superficialis (39.0%, 0.5-4 U/kg), flexor digitorum profundus (28.6%, 0.5–2 U), flexor pollicis brevis/opponens pollicis (27.6%, 0.3-1 U/kg) and biceps (27.1%, 0.5–6 U/kg). AbobotulinumtoxinA was well-tolerated at these doses; muscular weakness was reported in 4.3% of children in the 8 U/kg group and 5.7% in the 16 U/kg group.Conclusions: These data provide information on the pattern of injected muscles and dose ranges used in this study, which were well-tolerated. Per protocol, most children received injections into the elbow and wrist flexors. However, there was a wide variety of other upper limb muscles injected as physicians tailored injection patterns to clinical need.

Reconstruction of hook grip function of the fingers in patients with traumatic brachial plexus injury.

We described a reconstruction method for restoring hook grip function of the fingers in patients with total brachial plexus injury. The paralysed latissimus dorsi muscle was transferred to the upper limb as a pedicle flap and sutured to the flexor digitorum profundus tendons. The muscle was then reanimated with two intercostal donor nerves to the thoraco-dorsal nerve. Fourteen young adult patients (mean 23 years, range 17 to 32 years) with traumatic brachial plexus injury who underwent reconstruction using this technique from 2000 to 2019. After mean follow-up of 65 months (range 20 to 170), finger flexion of strength greater than or equal to M3 was achieved in 10 of the 14 patients. The mean weight that could be lifted using a hook grip was 2.6 kg, and that which could be lifted with both hands was 4.1 kg. The intercostal nerve-innervated latissimus dorsi muscle transfer can provide useful hook grip hand function without the need to sacrifice donor vessels or healthy muscles.Level of evidence: IV.

Locating the anterior interosseous nerve in relation to the surgically relevant landmarks of the forearm: A cadaveric study

BackgroundThis study emphasizes locating the anterior interosseous nerve (AIN) related to its level of origin, number, and lengths of its muscular branches and relation to surgically important landmarks such as the bi-epicondylar line, pronator teres, and Gantzer muscles. MethodsThe study was undertaken at a private Medical school in south India during 2019–20. The level of origin of AIN was measured from the bi-epicondylar line and its length was measured up to the upper border of the pronator quadratus using 44 cadaveric upper limbs. The number of branches given to flexor digitorum profundus (FDP) and flexor pollicis longus (FPL) was quantified and their lengths were measured. ResultsThe nerve originated at a mean distance of 41.56 mm from the bi-epicondylar line. In 12 upper limbs, FDP received two branches and in two limbs, it received three branches. In 13 upper limbs, FPL received two branches from AIN. It was observed that the muscular branches for FDP were shorter than those for FPL. Gantzer muscle was observed in 18 (40%) specimens and was found superficial to the nerve. ConclusionThe muscular branches of AIN had a variable pattern of innervation. Multiple muscular branches to the FPL and FDP were observed in the upper 2/3rds of the forearm. These branches to FPL and FDP would aid as a source of nerve grafting and nerve transfer in the cases of upper extremity nerve palsies.

1101 Closed Traumatic Avulsion of Both Flexor Digitorum Tendons: A Novel Treatment Method

Abstract Case Report Closed tendon avulsion of both flexor tendons (Flexor Digitorum profundus [FDP] and Flexor Digitorum superficialais [FDS]) in the same finger is an extremely rare condition. We are proposing this subtype of injury be added as a type VI to the current Leddy and Packer classification for FDP avulsion injuries. The objective of this being an increase in awareness to avoid misdiagnosis and to aid in the subsequent management if encountered. We present the case of a 27-year-old male who presented with an avulsion of both flexor tendons from their respective insertions in the ring finger following a sporting injury causing hyperextension against an actively flexed distal interphalangeal joint. This condition has previously been reported twelve times in the literature. We propose a novel treatment method not described for previous cases and examine the successful method of treatment in this case.

MRI findings in chronic exertional compartment syndrome of the forearm: Using signal intensity ratio as a diagnostic tool.

BackgroundChronic exertional compartment syndrome (CECS) of the forearm is a rare but important cause of morbidity amongst athletes involved in strenuous upper limb activities. The diagnosis remains challenging due to the absence of objective, reproducible diagnostic studies.ObjectivesTo assess and quantify signal intensity (SI) changes of involved muscles in patients with CECS of the forearm compared to healthy control subjects competing in similar sporting disciplines. Also, to objectively measure MRI SIs within muscle compartments when using a pre- and post-exercise regime and calculating a signal intensity ratio (SIR) between post- and pre-exercise studies.MethodThe study retrospectively examined MRI scans of patients treated for CECS of the forearm and compared these to the MRI scans of asymptomatic high-level rowers. A specific, reproducible pre- and post-exercise MRI scanning protocol was utilised in both patient and control subjects between 2011 and 2020. Signal intensities were evaluated pre- and post-exercise in involved muscle groups and ratios were calculated.ResultsA total of 86 SIs were measured (43 pre- and 43 post-exercise) in nine study participants (five patients and four controls). After post:pre-exercise comparisons, a statistically significant difference was found between control and patient groups (p = 0.0010). The extensor carpi radialis, flexor digitorum profundus and flexor digitorum superficialis muscles were most commonly involved.ConclusionThis study confirms that significant SI changes are apparent in patients with CECS of the forearm when making use of a standardised pre- and post-exercise MRI protocol. Furthermore, SIR may be used to accurately diagnose CECS of the forearm.

Biomechanical study of a newly developed continuous double knots technique compared with the 4-strand double-modified Kessler technique for flexor tendon repair

PurposeIn this study we compare the biomechanical properties of a novel suture technique that we developed called the continuous double knots technique for repairing flexor tendon injuries with the standard 4-strand double-modified Kessler technique.MethodsThis was an experimental study. Eighty porcine flexor digitorum profundus tendons were harvested and divided randomly into two groups of 40. The first group (N = 40) was repaired using the 4-strand double modified Kessler technique and the second group (N = 40) was repaired using our new continuous double knots technique. The two groups were randomly divided and the ultimate failure load (n = 20) and cyclic testing to failure (n = 20) were compared.ResultsThe mean ultimate failure load was 25.90 ± 7.11 (N) and cyclic testing to failure 88 ± 47.87 (cycles) for the 4-strand double modified Kessler technique and 34.56 ± 6.60 (N) and 189 ± 66.36 (cycles) for our new continuous double knots technique. The T-test revealed a significant difference between the 2 techniques (p < 0.05). In terms of biomechanical properties in tendon repair, the continuous double knots technique group had a higher tensile strength than the 4-strand double-modified Kessler technique group. There were also significant differences between the ultimate failure load and cyclic testing to failure for the flexor tendon sutures.ConclusionsThe continuous double knots technique suture technique had significantly higher maximum tensile strength and cyclic testing than the 4-strand double modified Kessler technique in an in vitro study, and in thus an optional technique for flexor tendon repair.

Investigating the effects of flexor tendon shortening on active range of motion after finger tendon repair.

Evaluation of surgical effects is often done using simple cadaver experimentation. This study uses a robotic testbed to estimate the best-case clinical outcomes of flexor tendon shortening during repair surgery on cadaver hands. Nine fresh-frozen cadaver subjects were connected to an extrinsic index finger robotic muscle testbed and measurement system. The flexor digitorum profundus tendons were severed and surgically repaired at different shortening levels. The index finger's extrinsic tendons were robotically actuated using Hill-type muscle models to emulate the muscle force-length relationships. Extensor muscles were then activated to estimate the active range of motion (ROM) of the all-finger joints after surgery. The effects of metacarpophalangeal (MCP) joint extension limits and extensor muscle activation were also investigated. The resulting interphalangeal joint ROM was clinically graded. Active ROM of the finger decreases as tendon shortening increases ( ), like passive ROM. This results in a clinical reduction of functionality grade from excellent to good at 10 mm of shortening. Blocking MCP joint ROM and extensor activation also showed significant effects on recovered ROM ( and 0.86). Significant two-way interactions were also observed between shortening and MCP joint blocking ( ) and between shortening and extensor activation ( ). Results support clinical recommendations of limiting shortening to 10 mm. While this article provides additional experimental evidence for current surgical recommendations, it also validates a new robotic-cadaver methodology for predicting active hand recovery in terms of clinical measurements.

A novel technique to manage paradoxical extension: Case report

Paradoxical extension was first described, and termed “lumbrical-plus" finger, by Parkes in 1970. It is characterized by extension of the interphalangeal joints when flexing the fingers. The It is most common in the middle finger. Treatment involves lumbrical muscle release or a flexor digitorum profundus graft of appropriate length. A search of the literature found no reports of results of conservative management. The present case report describes a novel conservative technique for lumbrical-plus deformity.

Safe Approach for Flexor Digitorum Profundus I and II Using the Palmaris Longus Tendon

ObjectiveTo investigate a safe and accurate approach to achieve needle insertion for electromyography (EMG) of the flexor digitorum profundus (FDP) I and II muscles by identifying the anatomic relationship between the palmaris longus (PL) tendon, FDP muscle, and neurovascular bundle using ultrasonography. DesignDescriptive study SettingDepartment of physical medicine and rehabilitation. ParticipantsHealthy individuals (age, 20-70y) without any diseases (N=29; 15 men, 14 women; 58 forearms). InterventionsUltrasonography. Main Outcome MeasuresThe FDP I and II muscles were transversely scanned on the volar aspect of the forearm at the junction of the middle and distal third between the medial epicondyle and ulnar styloid process. The distances and angles from the medial border of the PL tendon to FDP I, FDP II, and median nerve were measured. ResultsThe probability of damage to the neurovascular structures and the accuracy of entering the FDP I and II muscles were calculated for 3 imaginary needle insertion angles (61.7°, 100.6°, and 90°). When the needle was inserted at an angle of 61.7°, it reached FDP I with an accuracy of 91.4%. Upon needle insertions at 90° and 100.6°, the needle reached FDP II with accuracies of 90% and 89.6%, respectively. In all 3 cases (61.7°, 90°, and 100.6°), there was no chance of penetrating the blood vessels or nerves. ConclusionEMG of FDP I and II can be performed precisely and safely with the anterior approach at the distal one-third between the medial epicondyle and ulnar styloid process using the PL tendon.

Wide-Awake Approach for Flexor Digitorum Superficialis Tendon Transfer Followed by Early Active Mobilization.

Background The standard clinical practice to treat closed ruptures of the flexor digitorum profundus (FDP) tendons includes free tendon grafting; however, it is not suitable when the muscle amplitude of the ruptured FDP is not sufficient. We report outcomes of six patients who underwent flexor digitorum superficialis (FDS) tendon transfer of the ring finger using the wide-awake approach to repair the closed rupture of the FDP tendon of the little finger in zone 3 or 4. Methods The patients were identified by reviewing our institutional billing records from January 2012 to October 2019 for the International Classification of Disease 10 code M66.3 that describes the diagnosis as “spontaneous rupture of flexor tendons.” Results The patients comprised two men and four women with an average age of 72.2 years (standard deviation [SD], 8.4 years). All patients were hospitalized after surgery to undergo early active mobilization. The average total active motion at the final evaluation was 201.8° (range: 85–248°). According to Strickland’s criteria, outcomes were excellent for two, good for three, and poor for one patient. No patients complained about the ring finger. Conclusion These results suggest that FDS tendon transfer is recommended when the muscle amplitude of the ruptured FDP is insufficient. We believe that the wide-awake approach and early active mobilization may contribute to satisfactory outcomes.

Technical challenges in chronic zone 2 flexor tendon reconstruction and analysis of function in toddler: A rare case Report

Introduction: Flexor tendon injury in zone 2 is challenging to treat, when child was presented late. As flexor tendon are smaller in size, the repair or reconstruction technique along with rehabilitation becomes very challenging. We report a technical challenge in chronic zone 2 flexor tendon reconstruction in toddler presented two month post accidental glass cut injury. Case presentation: An 18-month-old male toddler presented with inability to flex left little finger after twomonths post accidental glass cut injury proximal to proximal interphalangeal (PIP) joint in zone two of left index finger. The passive range of motion (RoM) of DIP was zero degree to 60 degrees and PIP joint RoM was zero to 95 degrees. Child was unable to do active flexion of PIP and DIP joint movement. The parents of child were counselled for exploration and staged reconstruction of flexor digitorum profundus (FDP) tendon using either flexor superficialis (FDS) slip or palmaris longus. One slip of FDS graft was harvested and utilised to reconstruct FDP. At two years follow up, the injured index finger was normal in cosmesis and function. The active DIP joint movement was 50 degrees with complete healing of surgical site. Conclusion: Zone two flexor tendon injury in toddlers needs thorough clinical judgement and assessment by ultrasonography to locate the cut ends of tendons. Reconstruction of pulley, FDP reconstruction using FDS slip and supervised rehabilitation is recommended surgical option to achieve excellent function.

Effect of a Flexor Digitorum Superficialis Hemitenodesis on Reducing Volar Plate Strains for Swan Neck Deformities.

Flexor digitorum superficialis (FDS) hemitenodesis is a common procedure to treat swan neck deformity (SND). We hypothesize that this surgical technique is a biomechanically effective way to reduce strain in the volar plate at the proximal interphalangeal joint (PIPJ). Fifteen digits from 5 cadaveric specimens were tested using a novel in vitro active finger motion simulator under 4 finger conditions: intact, SND, FDS hemitenodesis, and FDS hemitenodesis with distal interphalangeal (DIP) joint fusion. Tensile loads in FDS and flexor digitorum profundus (FDP) and joint ranges of motion were measured by electromagnetic tracking. In addition, strain gauges were inserted under the volar plate to measure strain during PIPJ hyperextension. Results were analyzed using 1-way repeated-measures analysis of variance tests. The SND condition increased volar plate strain by 176% ± 25% (P < .001) compared with the intact condition. The FDS hemitenodesis repair relieved more than 50% of the SND strain, restoring it to within no statistical difference from intact. The DIP fusion further reduced strain with no further statistical significance. At full flexion, FDS and FDP tendon loads diverged as a function of the test condition (P < .001). With the FDS hemitenodesis, the FDP load increased by 2.1 ± 1.5 N from the SND condition (P < .001), whereas the FDS load decreased by 1.3 ± 1.3 N (P = .012). The FDS hemitenodesis repair restored strains to within 3.0 milli-strain of the intact condition with no significant difference. Application of DIP fusion did not further protect the PIPJ from increased hyperextension and further exacerbated the imbalance of flexor tendon loads.

Retraction: Sliding Position of the Flexor Tendons Relative to the Hook of Hamate in CT Scans.

Background The aim of this study was to assess the height of nonunion formation injuring the ulnar-side finger flexor tendon, the positional relationship between the hook of the hamate and little finger flexor tendon was evaluated on CT scans. Methods The subjects were 20 healthy patients (40 hands) (14 males and 6 females, mean age: 28 years old). Their hands were imaged in extension and flexion of the fingers on CT. The position of the little finger flexor tendon was determined regarding the height of the hook of the hamate as 100%. Results The heights of the flexor digitorum profundus tendons were 46 ± 6% in extension and 44 ± 9% in flexion, and those of the flexor digitorum superficialis tendons were 87 ± 8% in extension and 91 ± 9% in flexion. Conclusions Our study suggested that 40% of the base of the hook of the hamate does not contact with the flexor tendon, suggesting that flexor tendon injury is unlikely to occur in that region.

Mid-term Results of Two-Stage Tendon Reconstruction of Zone II Flexor Tendon Injuries.

Secondary repair of flexor tendon injuries remains a challenging procedure for hand surgeons. Usually, secondary reconstruction should be performed by a staged approach. Two-stage surgical reconstruction of the flexor tendons by the Hunter technique is the salvage option in case of a severely damaged fibro-osseous canal or neglected flexor tendon injury. We report the results of staged flexor tendon reconstruction in 10 patients (10 fingers) with neglected or failed primary repair of flexor tendon injuries in zone II. Between 2012-2016, patients who underwent two-stage tendon reconstruction due to flexor digitorum profundus (FDP) sectioning or tearing in zone II with destruction of flexor pulleys and extensive scarring in the flexor tendon bed were included in the study. Ten patients included to study with a mean follow-up of 34 months (range 12-70 months) and the results were assessed by clinical examination and questionnaire. According to the Strickland score, one (20%) of the results were excellent, five (50%) were good, two (20%) were fair and two (20%) were poor. After the second stage, good to excellent results were achieved in 60% of patients, one patient needed graft tenolysis. These results were similar to the subjective scores given by the patients, four of whom complained of functional problems in daily life at follow-up. There was no complication after the first stage. But after the second stage, there was one bowstringing and one adhesion that require tenolysis. Hunter technique is still the reference procedure for the reconstruction of flexor tendons. The results of our study showed that two-stage tendon reconstruction which is applied in patients with tendon sheath disruption as a result of acute or delayed tendon injuries which are not possible for primary repair is reliable and satisfactory.

The effects of pistol grip power tools on median nerve pressure and tendon strains

ABSTRACT Objectives. Tendonitis and carpal tunnel syndrome are common cumulative trauma disorders that can occur with repetitive usage of pistol grip power tools. The role of reaction torque resulting in a forceful rotary displacement of the tool handle, as well as the role of applied grip force, is not clear in the development of these disorders. This study aimed to quantify the flexor tendon strains and median nerve pressure during a typical power tool operation securing a threaded fastener. Methods. Six fresh-frozen cadaver arms were made to grip a replica pistol grip power tool using static weights to apply muscle forces. A 5-Nm torque was applied to the replica power tool. The median nerve pressure and strains in the flexor digitorum profundus and superficialis tendons were measured using a catheter and strain gauges, at three wrist flexion angles. Results . The peak tendon strains were between 1.5 and 2% and were predominantly due to the grip force more than the transmitted torque. Median nerve pressure significantly increased with the wrist flexed versus extended. Conclusion . The results indicate that the contribution of the grip force to the tendon strain and median nerve pressure was greater than the contribution from the reaction torque.

Jersey Finger Repair

Jersey finger, also known as rugby finger, is an avulsion to the flexor digitorum profundus at its insertion on the base of the distal phalanx (zone I). It is frequently caused by forceful extension of the distal interphalangeal joint while actively flexing the flexor digitorum profundus. The tendon may tear from the distal phalanx independently or may avulse with a bony fragment. A classification system has been developed to categorize distinct injury patterns based upon the level to which the flexor digitorum profundus tendon retracted and the presence or absence of a bony avulsion fracture. Flexor digitorum profundus tendon rupture has been reported in all age groups but is most common in athletes. The injury frequently occurs during contact sports, notably American football and rugby, when grabbing the jersey of an opposing player as the player pulls or runs away. Surgical repair is the definitive treatment for all cases of complete rupture of the flexor digitorum profundus tendon. This video demonstrates a surgical approach using the suture anchor technique to repair a jersey finger injury.

Outcome of carpal tunnel release surgery in patients with and without Linburg–Comstock anomaly

Anatomical variations may entail increased volume within the carpal tunnel and consequently the development of carpal tunnel syndrome (CTS) symptoms. The clinical importance of anomalous connection between the flexor pollicis longus (FPL) and flexor digitorum profundus (FDP) tendons was described by Linburg and Comstock. The objective of the present study was to compare postoperative outcomes of carpal tunnel release surgery in patients with and without Linburg–Comstock anomaly (LCA). Hands of CTS patients with and without LCA were evaluated for finger sensitivity, grip, tip, key and tripod pinch strength, pain intensity and Boston Carpal Tunnel Questionnaire score. Patients were evaluated preoperatively and 1, 3 and 6 months after surgery. Forty-six hands in 36 CTS patients with LCA and 50 hands in 38 patients without LCA were included. On all study parameters, no significant difference was found between CTS patients with versus without LCA. As outcomes are similar in both cases, LCA resection is not useful in patients with LCA and CTS. Preoperative diagnosis is unnecessary and screening for LCA is non-contributive for CTS evaluation.