Digital Extensor Research Articles

UK Trainee Experience with WALANT - An Audit of 102 Cases.

Background: WALANT has gained much popularity in recent years, especially with COVID-19. However, a recent survey of the American Society for Surgery of the Hand membership (i.e. attendings/consultants) showed that only 17% were exposed to WALANT during residency or fellowship training. There is much interest in WALANT from trainees, but interpretation of the type and volume to be administered is highly varied. Methods: The aims of this study were (1) to survey a group of plastic surgery trainees in the UK about their knowledge of WALANT formulas, and (2) to compare trainee logbook records of WALANT procedures (if available) with published data from the UK. Results: All trainees were familiar with the 'standard' WALANT formula (1% lidocaine, 1:100,000 adrenaline ± 8.4% NaHCO3) described by Lalonde. However, because of local formularies, rather than 1:100,000 adrenaline, all used 1:200,000 adrenaline as it comes premixed in the UK. Other formulas used by UK trainees included 0.5% bupivacaine + 1:200,000 adrenaline, and mixing 1% lidocaine + 1:200,000 adrenaline with 1% lidocaine 1:1. In comparing available trainee WALANT records with published UK data, the average volume of WALANT used was 6.6 mls in the current study versus 12.9 mls for similar procedures (wound debridement and skin closure ± local flap, digital nerve repair, fingertip reconstruction, thenar injuries, phalangeal fracture and single digit extensor repair); specifically, for single digit flexor tendon repairs, this was 10 mls versus 16.3 mls. Conclusions: While the British Society for Surgery of the Hand (BSSH) have developed official guidance for the use of WALANT in the UK, it appears there remains much variation in interpretation and hence, application. Comparison of trainee logbook records of common hand surgery procedures suggests that most can be done with much less WALANT administered than previously reported, with safe and reproducible results. Level of Evidence: Level IV (Therapeutic).

Fetal development and growth of extensor tendons and their sheaths in the dorsal side of the wrist and hand: a histological study.

To understand considerable variations in number of adult extensor ten-dons at the dorsal side of the wrist and hand. We examined histological sections from 30 human fetuses of gestational age 7-39 weeks and crown-rump length 22-323 mm. At the carpal level, earlier or smaller fetuses showed a simpler configuration with fewer tendon slips, whereas later or larger fetuses had a greater number of tendon slips with considerable variations in number and topographical relationships. Tendon slips of the early extensor digitorum to the middle and ring fingers were always 1 or 2, but were seven or more at late term. A tendon of the extensor digitorum to the little fin-ger could not be distinguished from other tendons at the carpal bone level. At the meta-carpal bone level, however, it extended from the ring finger tendon toward two slips of the extensor digiti minimi tendon. At the distal carpal level at midterm and late term, in which the tendon sheath was lost, each of the extensor digitorum tendon slips further divided to provide a mediolateral linear cluster of thin bundles. This large number of tendon components joined and united together to provide a single tight tendon at the level of the metacarpophalangeal joints. The extensor pollicis longs tendon usually lost a membranous septation when it crossed the extensor carpi radialis brevis tendon. Tendon slips in the fourth and fifth canals of the sheath were most likely to reduce in number after birth depending on the mechanical demand.

Reconstruction of Chronic Soft Tissue Mallet Fingers: Outcomes of Step-Plasty vs. Purse-String Suture.

After failed conservative therapy or in the absence of any intervention, a rupture of the digital subcutaneous extensor tendon at the distal interphalangeal (DIP) joint, known as mallet finger, may lead to a chronic extension deficit due to excessive scarring and tendon elongation. Various surgical techniques to restore the extension of the distal phalanx have been proposed, but an optimal approach has not yet been established. To tighten the extensor tendon, a purse-string suture can be applied. Although it has shown efficacy, it can result in significant bulging and scar formation. Using the "abbreviato" technique, the elongated part of the extensor tendon is excised, and the tendon is re-sutured. Also, tenodesis has been described, particularly in pediatric cases. In this retrospective follow-up study, we aimed to investigate if the step-plasty procedure previously described by Baumeister provides comparable, if not superior, functional and aesthetic outcomes compared to existing techniques for patients with chronic mallet finger. In this retrospective study, a consecutive series of 68 patients with chronic mallet fingers was enrolled. Patients were treated surgically using step-plasty of the respective extensor tendon. After skin incision and tenolysis, the elongated extensor tendon was incised in a Z-like fashion and stepwise resected in the transverse portion of the Z. The functional and aesthetic effects of this step-plasty technique were compared with results of 44 patients previously treated using purse-string sutures of the extensor tendon and evaluated using Crawford's and Levante's criteria. In all patients undergoing the step-plasty procedure, the extension deficit was significantly reduced from an average of 42 degrees preoperatively to 11 degrees postoperatively. In contrast, the control group treated by purse-string sutures showed a slightly higher postoperative extension deficit of 15 degrees. According to Levante's criteria, the results of our step-plasty procedure were significantly better than those achieved with purse-string sutures. Our study demonstrated that the treatment of older or chronic subcutaneous extensor tendon ruptures using the step-plasty technique led to a significant reduction in extension deficits. According to Levante's criteria, the postoperative outcome was significantly better in comparison to the purse-string suture technique. Additionally, no skin resection was required to improve the extension capability of the distal finger joint, compared to established surgical procedures.

Identifying alterations in hand movement coordination from chronic stroke survivors using a wearable high-density EMG sleeve

Objective.Non-invasive, high-density electromyography (HD-EMG) has emerged as a useful tool to collect a range of neurophysiological motor information. Recent studies have demonstrated changes in EMG features that occur after stroke, which correlate with functional ability, highlighting their potential use as biomarkers. However, previous studies have largely explored these EMG features in isolation with individual electrodes to assess gross movements, limiting their potential clinical utility. This study aims to predict hand function of stroke survivors by combining interpretable features extracted from a wearable HD-EMG forearm sleeve.Approach.Here, able-bodied (N= 7) and chronic stroke subjects (N= 7) performed 12 functional hand and wrist movements while HD-EMG was recorded using a wearable sleeve. A variety of HD-EMG features, or views, were decomposed to assess alterations in motor coordination.Main Results.Stroke subjects, on average, had higher co-contraction and reduced muscle coupling when attempting to open their hand and actuate their thumb. Additionally, muscle synergies decomposed in the stroke population were relatively preserved, with a large spatial overlap in composition of matched synergies. Alterations in synergy composition demonstrated reduced coupling between digit extensors and muscles that actuate the thumb, as well as an increase in flexor activity in the stroke group. Average synergy activations during movements revealed differences in coordination, highlighting overactivation of antagonist muscles and compensatory strategies. When combining co-contraction and muscle synergy features, the first principal component was strongly correlated with upper-extremity Fugl Meyer hand sub-score of stroke participants (R2= 0.86). Principal component embeddings of individual features revealed interpretable measures of motor coordination and muscle coupling alterations.Significance.These results demonstrate the feasibility of predicting motor function through features decomposed from a wearable HD-EMG sleeve, which could be leveraged to improve stroke research and clinical care.

Articular Surface Damage Following Headless Intramedullary Nail Fixation of Proximal Phalanx Fractures

Offering the benefits of rigid fixation while minimizing soft tissue dissection, intramedullary implants have become a popular choice among hand surgeons. Their placement often requires traversing or passing in proximity to joint surfaces. This study aimed to assess the damage to the articular cartilage of the base of the proximal phalanx resulting from antegrade placement of threaded headless intramedullary nails. A cadaveric study comparing two techniques for antegrade placement of threaded headless intramedullary nails was conducted in 56 digits. The first entailed a single 2.1 mm intramedullary nail placed via the dorsal base of the proximal phalanx, whereas the second used two 1.8 mm intramedullary nails inserted via the collateral recesses of the phalangeal base. All specimens were analyzed for articular surface damage with the cartilage defect measured as a percentage of total joint surface area. Damage to the extensor tendons was also assessed in a subset of specimens. No significant difference in the percentage of articular surface damage was observed, with an average 3.21% ± 2.34% defect in the single 2.1 mm nail group and a 2.71% ± 3.42% mean defect in the two 1.8 mm nails group. There was no articular surface injury in 18% of digits in each group. Damage to extensor tendons was seen in three (9.4%) specimens and in all cases involved either the extensor indicis proprius or extensor digiti minimi. Hardware insertion using either the dorsal base of the proximal phalanx or the collateral recesses of the phalangeal base both demonstrated minimal articular cartilage damage and infrequent injury to the extensor tendons. With proper technique for antegrade insertion into the proximal phalanx, the cartilage defect observed often encompasses only a small percentage of the overall joint surface area.

Proximal lateral insertion portal of an intra-articular arthroscopic stifle lever: A cadaveric study.

To (1) Describe the proximal lateral insertion portal for the placement of an intra-articular distraction lever. (2) Assess for associated damage with the insertion of the lever and (3) evaluate the impact of duration of lever use on articular cartilage damage. Ex vivo canine cadaveric experimental study. Paired canine stifles from seven cadavers (14 stifles from dogs weighing >20 kg). A separate 0.5 cm proximal lateral portal was established adjacent to the lateral scope portal. A standard Ventura stifle thrust lever (VSTL) was inserted without removing the arthroscope. In Group A, the VSTL was placed in distraction for 5 min while in Group B the VSTL was placed for 10 min. The stifle joints were disarticulated and evaluated for associated damage to the long digital extensor tendon and iatrogenic articular cartilage injury (IACI) via India ink assay. No damage to the long digital extensor tendon was noted in any of the specimens during dissection. Superficial IACI was present in all specimens. There were no differences between groups when assessing for overall IACI. A proximal lateral portal and insertion of a standard VSTL can be performed without removing the arthroscope. The use of a proximal lateral lever portal without repositioning the arthroscope was repeatable without damaging the long digital extensor tendon. A duration of up to 10 min in which the thrust lever was engaged did not result in increased visual cartilage damage.

Appendicular myology of Skorpiovenator bustingorryi: A first attempt to reconstruct pelvic and hindlimb musculature in an abelisaurid theropod.

We present the pelvic and hindlimb musculature of the abelisaurid Skorpiovenator bustingorryi, constituting the most comprehensive muscle reconstruction to date in ceratosaur theropods. Using extant phylogenetic bracket method, we reconstructed 39 muscles that can commonly found in extant archosaurs. Through the identification of bone correlates, we recognized thigh and hindlimb muscles including knee extensors, m. iliofibularis, m. flexor tibialis externus, mm. caudofemorales, mm. puboischiofemorales, and crus muscles important in foot extension and flexion (e.g., m. tibialis anterior, mm. gastrocnemii). Also, autopodial intrinsic muscles were reconstructed whose function involve extension (m. extensor digiti 2-4), flexion (mm. flexor digitorum brevis superficialis), interdigital adduction (m. interosseus dorsalis) and abduction (m. interosseous plantaris, m. abductor 4). Abelisaurids like Skorpiovenator show a deep pre- and postacetabular blade of the ilia and enlarged cnemial crests, which would have helped increasing the moment arm of muscles related to hip flexion and hindlimb extension. Also, pedal muscles related to pronation were probably present but reduced (e.g., m. pronator profundus). Despite some gross differences in the autopodial morphology in extant outgroups (e.g., crocodilian metatarsus and avian tarsometatarsus), the present study allows us to hypothesize several pedal muscles in Skorpiovenator. These muscles would not be arranged in tendinous bundles as in Neornithes, but rather the condition would be similar to that of crocodilians with several layers formed by fleshy bellies on the plantar and dorsal aspects of the metatarsus. The musculature of Skorpiovenator is key for future studies concerning abelisaurid biomechanics, including the integration of functional morphology and ichnological data.

Cone beam computed tomography and cross-sectional anatomy of the region of the fetlock in the horse (Equus caballus).

This study aimed to delineate the detailed anatomy of the metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints in healthy horses using cone beam computed tomography (CBCT). The fetlock region of 15 cadaveric forelimbs and 14 cadaveric hindlimbs from nine adult horses without orthopaedic disease underwent CBCT scanning. Additionally, arthrography CBCT scans were conducted following intra-articular injection of a radiopaque contrast medium containing blue epoxy resin dye. Subsequently, limbs were frozen and sectioned to visualize anatomical structures in sectional planes corresponding to selected CBCT images. CBCT proved suitable for detailed visualization of the bony components of the fetlock region. Furthermore, the common digital extensor tendon, superficial and deep digital flexor tendons, suspensory ligament, and straight and oblique sesamoidean ligaments were identifiable on CBCT images. However, certain ligaments, such as the collateral sesamoidean ligaments and intersesamoidean ligaments, were not clearly identified. The hyaline cartilage of the MCP and MTP joint facets was assessable on the post-contrast sequence. In cases where a radiographic or ultrasound examination cannot provide a definitive diagnosis and determine the extent of disease, CBCT can provide additional valuable data on the equine MCP and MTP joint. The images obtained in this study can serve as a reference for CBCT examination of the equine MCP and MTP joint.

EFFECTS OF RIBOSE-INDUCED GLYCATION ON THE ELASTIC MODULUS OF COLLAGEN FIBRILS OBSERVED BY ATOMIC FORCE MICROSCOPY

The interplay between diabetes mellitus and the structural integrity of collagen has significant implications for tissue functionality and disease progression. The aim of this study was to empirically investigate the effects of ribose-induced glycation on the biomechanical properties of collagen fibrils, using atomic force microscopy for precise measurements. Methodology. We used collagen fibrils from the common digital extensor (CDE) and superficial digital flexor (SDF) tendons of an adult bovine model to mimic the glycation processes that occur in diabetic pathology. The samples underwent controlled glycation by incubation with ribose for 24 hours and 14 days compared to phosphate buffered saline treated controls. A Bioscope Catalyst atomic force microscope (Bruker, USA) was used for all atomic force microscopy imaging in this study. Scientific novelty. Our results show a marked increase in the elastic modulus of collagen fibrils after ribose treatment, indicating stiffening with glycation. Notably, SDF fibrils showed a greater increase in stiffness after 24 hours of ribose exposure compared to CDE fibrils, suggesting variations in glycation rates relative to fibril anatomy. Statistical analyses confirmed the significance of these findings and provided a model for understanding similar processes in human diabetes. Conclusions. The different response to glycation observed between CDE and SDF fibrils prompts further investigation into the role of anatomical and structural factors in glycation susceptibility. Identification of tissues at higher risk of glycation-induced damage could lead to the development of targeted prevention strategies for diabetic complications. In addition, the potential for pharmacological intervention to inhibit glycation processes or enhance advanced glycation end products (AGEs) degradation offers a promising avenue for mitigating the progression of diabetes-related complications. The results of this study highlight the potential of ribose-induced changes in collagen as a model for diabetes-related tissue changes and propose a mechanistic framework that could guide the development of interventions aimed at mitigating the effects of collagen-related diabetic complications.

Single tendon transfer of the flexor carpi ulnaris for high radial nerve palsy

Complete radial nerve palsy results in a lack of extrinsic extensors of the wrist, fingers and thumb. The optimal treatment of persistent hight radial nerve palsy is tendon transfer, which leads generally to acceptable results with better extension of the fingers and ability to grasp large objects. There are a multiple techniques of tendon transfers from a single to multiple one generally three tendons, however a single flexor carpi ulnaris tendon (FCU) transfer has some advantages, including simplicity, shorter operation time, less morbidity and less surgical scars, which can be important in some patients, particularly women. We present a case report of single tendon transfer of the FCU to the digital extensors for high radial nerve palsy secondary to closed diaphyseal humeral fracture.

Quantitative anatomy of the extensor digiti minimi muscle in the growing human fetus.

Introduction Age-specific reference intervals for the extensor digiti minimi muscle (EDMM) in the human fetus may be relevant in the detailed evaluation of the musculoskeletal systems with potential relevant aspects for surgical treatment. The aim of the study was to examine the age-specific reference intervals and growth dynamics of the EDMM in relation to its length, width, projection surface area and volume. Material and methods The examined material included 70 human formalin-fixed fetuses of both sexes (37♀, 33♂) aged from 17 to 29 weeks. With the use of anatomical dissection every EDMM was visualized, recorded in a form of JPG formats and analyzed by the digital image analysis system and statistical methods. Results No variability of the EDMM was found. All the morphometric parameters of the EDMM revealed neither sex nor laterality differences. With fetal age most linear parameters of the EDMM concerning its examined lengths and widths increased in accordance with natural logarithmic functions. The only two exceptions to this referred to the belly width of EDMM measured at its mid-length and the tendon width of EDMM measured proximal to the extensor retinaculum of wrist, which both followed square root functions. The projection surface areas of the EDMM followed natural logarithmic functions, while the volumetric growth of the EDMM was proportionate to fetal age. Conclusions The variability of the EDMM in the human fetus is minimal. The morphometric data of the EDMM represents age-specific reference intervals of clinical significance. Morphometric parameters of the EDMM reveal neither sex nor laterality differences. The EDMM displays three different growth dynamics: from gradual growth deceleration according to both natural logarithmic functions (total length of the muscle and its tendons, belly length, tendon lengths, belly width at its origin, tendon width at its insertion, and projection surface areas) and square root functions (belly width at its mid-length and tendon width in the pre-retinacular segment) to a proportionate growth (total volume).

Ultrasonographic Evaluation of Nail Involvement in Patients With Axial Spondyloarthritis.

This study aimed to evaluate the nail units of patients with axial spondyloarthritis (ax-SpA) using ultrasound and to identify any subclinical changes. We also aimed to examine the relationship between clinical enthesitis scores and nail involvement in patients with ax-SpA. The study included 40 patients with ax-Spa, 40 patients with psoriatic arthritis (PsA), and 40 healthy controls. The thickness of the nail plates, morphological changes, the thickness of the proximal nail units, the thickness of the nail beds, and power Doppler signal intensities were evaluated and compared. Maastricht Ankylosing Spondylitis Enthesitis Score and Spondyloarthritis Research Consortium of Canada Enthesitis Index were also evaluated in patients with ax-SpA. There was no significant difference between the thickness of the nail plates of the three groups (P > .05). The first nail bed thickness of ax-SpA cases was significantly higher than the control group (P = .046), and the fourth and fifth nail proximal unit thicknesses of the control group were significantly lower than the ax-SpA and PsA groups (P = .023, P = .017). We also found that the Wortsman scores of the cases with PsA were significantly higher than the ax-SpA and control groups (P = .0001). The thickness of the proximal nail unit adjacent to the insertion of the digital extensor tendon, which is considered as the enthesis area, is similar to the patients with PsA in patients with ax-SpA, especially in the fourth and fifth fingers compared to the control group. On the other hand, almost no structural changes in nail plates were observed in patients with ax-SpA group.

A detailed anatomical study of the muscles of the forearm and hand in the Anubis baboon (Papio anubis) in comparison with humans

The anatomy of the human forearm and hand has been described in great detail, including possible anatomical variations. For animals, this information is still not complete. The aim of this case study was to describe the anatomy of the muscles of the forearm and hand in one individual of the Anubis baboon and to compare this information with the available data on the subject and with the anatomical standard and possible variations in humans. The biggest differences were noted in the extensor digiti minimi, where two separate muscle bellies were dissected. We believe that in this individual it was the extensor digiti quarti proprius and extensor digiti quinti proprius muscles. Anatomical standard has not yet been established for the thenar, hypothenar, and contrahentes muscles in the deep layer of the muscles of the forearm of the baboon and literary sources differ notably in some information. Determining the anatomical standard and anatomical variability of individual structures in animals is an important contribution to the field of veterinary surgery and orthopaedics.

Arthroscopic Long Digital Extensor Tenodesis: Technique and Outcome in a Dog

AbstractAvulsion of the long digital extensor (LDE) tendon is an uncommon cause of pelvic limb lameness in the dog. Surgical exploration is recommended with reattachment of the tendon and the avulsed fragment of bone using a small screw in lag fashion. In more chronic cases, the bone fragment can be removed, and the tendon attached by suture or staple to the proximolateral tibia. Arthroscopic tenodesis of the LDE has not been previously reported in the literature. A 6-year-old male neutered Labrador Retriever was presented for evaluation of a left pelvic limb lameness that was localized to the stifle. Avulsion of the LDE tendon was diagnosed based on palpation and radiographs. Arthroscopic assessment of the joint was performed. The origin of the LDE was freed with the use of a mechanical 3.0-mm shaver and an arthroscopic punch. The freed end was then exteriorized from the lateral portal and mineralized tissue removed. The tendon end was captured using no. 2 braided suture loop using a SpeedWhip technique. A 4.75-mm SwiveLock® polyetheretherketone anchor was utilized to fasten the tendon in the proximal groove of the LDE. The dog returned to dock diving by 16 weeks postsurgery at the preinjury level of performance and remained free of lameness at 30 months postoperatively. Arthroscopic long digital tendon tenodesis is a feasible surgical option in canine patients.

New Insights into Boxer's Knuckle Injury of the Little Finger.

The original description of boxer's knuckle injury of the fifth ray mentions that the injury occurs between the extensor digitorum communis (EDC) and the extensor digiti minimi (EDM). Subsequent reports claim similar findings. Anatomical studies show that the EDC of the fifth ray is absent in most patients, while the EDM is generally composed of two slips. We present a modification of the current description of boxer's knuckle injury of the little finger based on the correlation between advanced preoperative 3D imaging and intraoperative findings. Five patients were investigated preoperatively using high-resolution ultrasound and 3D tendon reconstruction-based MR arthrography. Surgical exploration identified the lesion site relative to the EDM and EDC. All patients had two slips of the EDM and no EDC to the fifth ray. The injury appeared as a longitudinal tear of the EDM between its two slips. The mean gap was 7.8 mm (range 4.5-10 mm) on the pathological side vs. 1.3 mm (range 1-2 mm) on the healthy contralateral side. We believe that previous descriptions of boxer's knuckle of the fifth ray are inaccurate. High-resolution ultrasound and 3D reconstructions based on MR arthrography are reliable diagnostic tools allowing to locate the injury with precision.

Distal forearm squeeze test for the diagnosis of digital flexor tendon injuries

BackgroundThe forearm/wrist squeeze/compression test has been used to examine digital flexor tendon injuries with varied names. Furthermore, the test has not been minutely described and its mechanism remains unclear. We renamed the test the “distal forearm squeeze test”. The purpose of this study was to elaborate on the test and elucidate the mechanism.MethodsTwo patients with digital flexor tendons ruptured in zone 3 and zone 1 respectively and 50 outpatients with intact digital tendons underwent the test. Then the test was performed on 3 chickens under 4 conditions. First, when the digital flexor and extensor tendons were all intact. Second, after the flexor tendons of the third toe were transected. Third, after the flexor tendons of all toes of the foot were transected. Finally, after the flexor and extensor tendons of all toes of the foot were transected.ResultsIn the patient with digital flexor tendons ruptured in zone 3, the test showed that the injured digit was flexed slightly while the uninjured digits were flexed obviously. In the patient with digital flexor tendon ruptured in zone 1, after separate stabilization of the proximal interphalangeal (PIP) joints of the injured and uninjured fingers in extension, the test showed that the distal interphalangeal joint of the patient’s injured finger had no response, while those of the uninjured fingers were flexed. All 50 subjects showed clenched or half-clenched hands in response to the test. The test showed that all toes were flexed when the digital tendons of the chicken were intact. All toes were flexed except the third toe after the flexor tendons of the third toe were transected. All toes were extended after all the digital flexor tendons were transected. All toes had no response after all the digital flexor and extensor tendons were transected.ConclusionsThe distal forearm squeeze test is valuable in examining digital flexor tendon injuries. If only the flexor digitorum profundus tendon is examined, the PIP joint of the finger should be stabilized in extension during the test.

Novel Therapeutic Approach for Extensor Digiti Minimi Tendon Traction in Chronic Ulnar-Sided Wrist Pain Diagnosed as Triangular Fibrocartilage Complex Injury: A Case Report

Novel Therapeutic Approach for Extensor Digiti Minimi Tendon Traction in Chronic Ulnar-Sided Wrist Pain Diagnosed as Triangular Fibrocartilage Complex Injury: A Case Report

Intraspecific anatomical variations of the extensor tendons of the carpus and digits with a reexamination of their insertion sites in the domestic dog (Canis lupus familiaris): a cadaveric study

BackgroundThe aim of the current study was to investigate the frequency of variations of the extensor tendons of the carpus and digits in the domestic dog (Canis lupus familiaris) with a reexamination of their insertions as well as the morphometric measurements of the tendons and the brachioradialis muscle. In total, we investigated 68 paired thoracic limbs of the domestic dog (16 females and 18 males) which were fixed in a 10% formalin solution.ResultsThe extensor carpi radialis (ECR) tendons showed striking variations in both splitting and insertion sites. In 4.4% of dissections, ECR had three tendons. Of these tendons, the extra tendon either attached independently on the fourth metacarpal bone (one right) or joined its counterpart tendon at the distal end (cross-connections) (one bilateral). It is worth mentioning that one of the ECR tendons split into two or three slips which inserted on the first, second, third, or fourth metacarpal bone in 11 (16.2%) of the specimens. In addition, we found a long tendinous slip originating from the ECR tendons to digit II or III in 7.4% of the distal limbs. The most common type of contribution to digit III was a third tendon of the extensor digiti I et II (ED III) joining the extensor digitorum lateralis (EDL III) with a frequency of 17.6%. In other types of variations, the contribution to digit III was incomplete. A part of the abductor pollicis longus (APL) deep to the superficial part of the flexor retinaculum seemed to continue up to the flexor digitorum superficialis (FDS) tendon.ConclusionsThe rare intraspecific variations of the extensor tendons of the manus described in the current research are valuable from both clinical and phylogenetic perspectives. Nonetheless, their functional importance needs more studies.

The retinacular ligaments of the digital extensor expansion revisited: An anatomical and biomechanical study.

Our aim was to clarify the anatomy and function of the retinacular ligaments. Forty-eight fingers were dissected and the thickness of the oblique retinacular ligament (ORL) was graded. In four fingers, the motion in the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints was subjected to an in-depth analysis before and after sectioning of either the lateral bands (LB) or the ORLs. The function of the ORLs in restricting flexion of the DIP joint with full extension of the PIP joint was measured in 10 fingers. An ORL could be identified on both sides in all 48 fingers. The distribution of the insertion on the proximal phalanx was 7/96 (7%) in the distal third, 70/96 (73%) in the middle third and 19/96 (20%) in the proximal third. Among the specimens, 29% were graded as having a strong bundle of fibers, 51% as having well-defined and regular fibers and 20% as having thin and sparse fibers. With the PIP joint extended, there was a statistically significant increase in flexion of the DIP joint after the ORL was cut. After the LB was sectioned, the ORL was able to extend the DIP joint with an extension lag of 10-22°. Cutting the ORL did not affect the ability to extend that joint. We conclude that the retinacular ligaments are consistent. Their major role is not connected with finger movement, but to provide stabilizing links between the PIP and DIP joints. They are active in not only specific, uncommon finger positions but also in ordinary use of the fingers.

The Medial Triquetrohamate Portal: A New Portal in Wrist Arthroscopy. Anatomical Study.

Introduction Continuing advances in wrist arthroscopy and better understanding of carpal conditions have created the need to design new wrist access portals that facilitate the implementation of new surgical techniques. The aim of this study was to define and verify the safety of the medial triquetrohamate (MTH) portal. Description of the technique The MTH portal is located about 5-10 mm ulnar and 2-3 mm distal to the midcarpal ulnar portal, ulnar to the extensor digitorum communis (EDC) tendon of the fourth and fifth fingers, and radial to the extensor digiti quinti (minimi) (EDQ) tendon. Methods An anatomical study was performed on 15 upper limb specimens from 15 human cadavers. Iatrogenic injuries to potentially at-risk neurovascular and tendinous structures were assessed, and the distance from the portal to these structures was measured. Results There were no iatrogenic injuries to the structures at risk. Mean distances from the MTH portal to the EDC tendon of the fourth and fifth fingers and to the EDQ tendon were 4.67 ± 0.35 mm and 7.27 ± 0.18 mm, respectively. No differences were observed between the left and right wrists. The distance from the MTH portal to the dorsal sensory branch of the ulnar nerve was 15.07 ± 0.44 mm. The structure with the highest risk of injury was the EDC tendon of the fourth and fifth fingers, with a distance of less than 5 mm. Conclusions The MTH portal is safe, reproducible and facilitates the implementation of various techniques related to midcarpal pathology.