The Sensitivity of the Endpoint Forces of Thumb Extrinsic and Intrinsic Muscles to Changes in Joint Angles, Muscle Moment Arms and Bone Lengths in the Flexed Thumb.

A previous study showed in situ measurements of thumb-tip forces produced by muscles vary substantially among cadaveric specimens. Potential sources of variability include inter-specimen anatomic differences and postural deviations from the nominal posture in which the specimens were tested. This study aimed to theoretically determine the variation in thumb-tip force caused by inter-specimen differences in thumb anatomy and posture. We developed a two-dimensional mathematical model of force production at the thumb tip based on published estimates of muscle moment arms, bone length, and joint angle measurements from nine cadaveric specimens. The model was placed in a flexed posture. Using the model, we calculated variations in magnitude and direction of each muscle's thumb-tip force induced by a ±1 standard deviation (or equivalent) variation in each bone length, the moment arm of the muscle (i.e., anatomic factors), and each joint angle (i.e., postural factor). For most muscles, inter-specimen differences in the metacarpophalangeal (MP) joint angle produced at least a 75% larger variation in thumb-tip force magnitude than that produced by other factors. For all muscles, differences in the interphalangeal joint angle among specimens produced the largest variation in thumb-tip force direction. For some muscles, inter-specimen differences in bone lengths, moment arms, and MP joint angles also produced large variations in thumb-tip force direction. This study suggests deviation from the nominal flexed thumb posture and large measurement variability in muscle moment arms are primary and secondary sources, respectively, of variability in thumb-tip forces produced by the majority of thumb muscles. Further, this study suggests a more careful approach to standardizing the thumb posture would likely improve current measurements of thumb-tip forces.Clinical Relevance- This work describes the influence of anatomic and postural factors on thumb-tip forces that thumb muscles produce. The results of this work have implications for musculoskeletal modeling and surgical reconstruction of grasp.

Prevalence, coincidence and distribution patterns of sesamoid bones of the hand / Patrones de prevalencia, coincidencia y distribución de los huesos sesamoideos de la mano

SUMMARY: The aim of this study is to identify the prevalence and distribution patterns of sesamoid bones at the metacarpophalangeal (MCP) and interphalangeal (IP) joints and to determine if there is an association between the distribution patterns and age, gender, and hand side. Patients who had a direct radiograph of the hand obtained between 2019-2020 were retrospectively evaluated. All radiographs were evaluated in terms of the prevalence, coincidence, and distribution patterns of sesamoid bones. Presence of an association between distribution patterns and age, sex and side was also assessed. A total of 1501 hand radiographs were included into the study. There were 12 different patterns of sesamoid bone distribution. The most common distribution pattern was the presence of sesamoid bone at the first MCP joint only (25.8 %). There was a positive correlation between the second and third MCP, second and fifth MCP, second and first IP, third and fourth MCP and fifth MCP and first IP joints. The pattern with a sesamoid bone at the first MCP joint only was more prevalent among males, whereas the pattern involving coincidence of sesamoid bones at the first, second, fifth MCP and first IP joints was more prevalent among females (p<0.001, p=0.031). A positive correlation was observed between age and the number of MCP joints with sesamoid bones (p<0.001). The number of MCP joints with sesamoid bones was found to be higher in females (p<0.001). This study is important in that it provided anatomical data that can be guiding for clinicians in terms of diagnosis and management of hand disorders.

RESUMEN: El objetivo de este estudio fue identificar la prevalencia y los patrones de distribución de los huesos sesamoideos en las articulaciones metacarpofalángicas (MCF) e interfalángicas (IF) y determinar si existe una asociación entre los patrones de distribución y la edad, el sexo y el lado de la mano; fueron evaluadas retrospectivamente radiografías de la mano obtenidas en 2019- 2020. Todas las radiografías se evaluaron en términos de prevalencia, coincidencia y patrones de distribución de los huesos sesamoideos. También se evaluó la presencia de una asociación entre los patrones de distribución y la edad, el sexo y el lado. Se incluyeron en el estudio un total de 1501 radiografías de mano. Se observaron 12 patrones diferentes de distribución de los huesos sesamoideos. El patrón de distribución más común fue la presencia de hueso sesamoideo solo en la primera articulación MCF (25,8 %). Hubo una correlación positiva entre la segunda y la tercera MCF, la segunda y la quinta MCP, la segunda y la primera IF, la tercera y cuarta MCF y la quinta MCF y las primeras articulaciones IF. El patrón con un hueso sesamoideo en la primera articulación MCF fue más prevalente entre los hombres, mientras que el patrón de coincidencia de los huesos sesamoideos en la primera, segunda, quinta articulación MCF y la primera articulación IF fue más prevalente entre las mujeres (p <0.001, p = 0,031). Se observó una correlación positiva entre la edad y el número de articulaciones MCF con huesos sesamoideos (p <0,001). El número de articulaciones MCF con huesos sesamoideos era mayor en las mujeres (p <0,001). Este estudio es importante debido a que proporcionó datos anatómicos que pueden ser una guía para los médicos en el diagnóstico y tratamiento de los trastornos de la mano.

Palpation of the lateral bands of the extensor apparatus of the fingers. Anatomy of a neglected clinical finding.

This study aimed to determine by ultrasonography, and cadaveric dissection, whether the firm cords felt by palpation at the sides of the proximal phalanx (PP), actively flexing, and extending the proximal interphalangeal (PIP) joint while keeping the metacarpophalangeal (MCP) joint extended are the lateral bands (LBs) of the extensor apparatus. If so, palpation of the LBs could help evaluate hand conditions that impact the digits' intrinsic muscles. To this end, the PP of the middle and ring fingers of the dominant hand of seven subjects were studied by palpation on both sides. Ultrasonography (US) was performed with a hockey-stick transducer placed on the ulnar side. Five cadaveric hands were dissected, exposing the dorsal extensor apparatus. On palpation, a firm cord was consistently felt at the PP's sides in all subjects. These cords moved widely forward on PIP flexion and backward with PIP extension. By US scanning, the cords corresponded to the LBs. However, the forward movement had only a median of 1.8 mm (range 0.7-3 mm) in the middle finger and a median of 1.1 mm (range 0.3-2.7 mm) in the ring finger compared with an estimated 5-10 mm upon palpation. Cadaveric dissection confirmed the forward movement of the LBs in PIP flexion. We concluded that the firm cords felt at the PP sides are the LBs of the extensor apparatus. We confirmed their movement with the active flexion/extension of the PIP joint. Comparing the wide palpatory and the meager US motion, a haptic illusion of motion may be present.

Ultrasound and clinical findings in the metacarpophalangeal joint assessment of show jumping horses in training.

BACKGROUND: Physical exercise is known to cause significant joint changes. Thus, monitoring joint behavior of athletic horses is essential in early disorders recognition, allowing the proper management. OBJECTIVES: The aims of this study were to determine the morphological patterns, physical examination characteristics and ultrasound findings of show jumping horses in training and to establish a score-based examination model for physical and ultrasound follow-ups of metacarpophalangeal joint changes in these animals. METHODS: A total of 52 metacarpophalangeal joints from 26 horses who were initially in the taming stage were evaluated, and the horses' athletic progression was monitored. The horses were evaluated by a physical examination and by B-mode and Doppler-mode ultrasound examinations, starting at time zero (T0), which occurred concomitantly with the beginning of training, and every 3 months thereafter for a follow-up period of 18 months. RESULTS: The standardized examination model revealed an increase in the maximum joint flexion angles and higher scores on the physical and ultrasound examinations after scoring was performed by predefined assessment tools, especially between 3 and 6 months of evaluation, which was immediately after the horses started more intense training. The lameness score and the ultrasound examination score were slightly higher at the end of the study. CONCLUSIONS: The observed results were probably caused by the implementation of a training regimen and joint adaptation to physical conditioning. The joints most likely undergo a pre-osteoarthritic period due to work overload, which can manifest in a consistent or adaptive manner, as observed during this study. Thus, continuous monitoring of young athlete horses by physical and ultrasound examinations that can be scored is essential.

Thumb Metacarpophalangeal Ulnar and Radial Collateral Ligament Injuries.

Thumb metacarpophalangeal collateral ligament injuries are common in athletes and occur via forced abduction or hyperextension. Management primarily depends on the grade of ligamentous injury and the presence of a Stener lesion or large avulsion fracture. Surgeons should consider the athlete's position, hand dominance, duration of season remaining, and goals. Shared decision making regarding timing of surgery is imperative. Acutely, primary ligamentous repair with or without augmentation is achievable. Chronic collateral ligament injuries are effectively treated with ligament reconstruction. Numerous surgical techniques have been described without 1 showing superiority. Postoperative rehabilitation protocols vary based on repair quality and sports-specific considerations.

Anatomical relationship between the sagittal band and extensor tendon of the thumb: a focus on variations of the extensor pollicis brevis tendon insertion.

The sagittal band of the finger is an aponeurosis-like structure surrounding the metacarpophalangeal joint. Sagittal band rupture causes extensor tendon dislocation from the dorsal side of the metacarpophalangeal joint. The thumb has two extensor tendons: extensor pollicis longus and extensor pollicis brevis tendons. Multiple studies have reported variations of extensor pollicis brevis tendon insertion. However, it remains unclear how the thumb sagittal band envelopes the extensor pollicis longus and extensor pollicis brevis tendons. This study investigated the anatomical relationship between the sagittal band and the two extensor tendons of the thumb. One hundred hands (47 right, 53 left) from 54 cadavers were examined to assess the detailed structure of the thumb sagittal band and extensor pollicis longus and extensor pollicis brevis tendons. We found that the thumb sagittal band enveloped both the tendons either separately (type I) or collectively (type II). Thirty-four cases (34.0%) were type I and 66 cases (66.0%) were type II. The extensor pollicis longus and extensor pollicis brevis tendons enveloped in the type I thumb sagittal band were inserted on different sites, respectively, whereas those tendons enveloped in the type II thumb sagittal band were inserted on the same sites. This study demonstrated that differences in the type of thumb sagittal band are closely associated with variations in extensor pollicis brevis tendon insertion. We predicted that these differences contribute to the sliding distance between the extensor pollicis brevis and extensor pollicis longus tendons and affect the pathophysiology of extensor tendon dislocation.

The Pathogenesis and Treatment of the Stiff Finger.

"Stiff finger," defined as a finger with decreased range of motion in one or more joints, is commonly found after hand injury and is classified into flexion or extension deformities. Pathogenesis is due to dysfunction in one or more of the following anatomic components: (1) osseous and articular; (2) capsuloligamentous; (3) musculotendinous units; (4) soft tissue and fascia. Evaluation and treatment are based on accurate identification and correction of pathologic structures. The mainstay of treatment is directed hand therapy with exercises and splinting to mobilize stiff joints. Operative interventions are offered after gains from therapy have been exhausted.

Sexual dimorphism in the anatomy of the ulnar collateral thumb ligament.

BACKGROUND: Treatment of ruptured ulnar collateral thumb metacarpophalangeal (MCP) joint ligaments (UCL) necessitate a profound anatomic knowledge for optimal surgical repair in order to preserve range of motion and ensure postoperative joint stability. Therefore, knowledge of the angle between the UCL and the longitudinal axis of the first metacarpal bone could be useful. METHODS: In this study 46 ulnar collateral thumb MCP joint ligaments in 15 male and 15 female embalmed anatomic specimens were dissected and the angles between the longitudinal axis of the first metacarpal bone and the proper (PUCL) as well as the accessory ulnar collateral thumb MCP ligament (AUCL) were measured. RESULTS: In male specimens the angle for the PUCL measured on average 133.5° (±2.35°) and 122.75° (±3.8°) for the AUCL. A significantly different angle was measured for female specimens which showed on average 137.88° (±3.51°) for the PUCL and 128.65° (±4.14°) for the AUCL. CONCLUSIONS: Optimal surgical repair or reconstruction of torn ulnar collateral thumb MCP joint ligaments should aim for an angle of approximately 135° in PUCL and 126° in AUCL in relation to the longitudinal axis of the metacarpal bone. Differences in men and women should be considered if possible. LEVEL OF EVIDENCE: IV (anatomic study).

The Flexor Pollicis Longus Tendon Does Not Lie Parallel to the Thumb Metacarpal.

BACKGROUND: Repair of the flexor pollicis longus (FPL) tendon by tendon retriever can be challenging because of uncertainty of the optimal direction. This study aims to describe the FPL tendon path in the thenar eminence. METHODS: In 18 hands of 9 cadavers, the angle of the FPL tendon was, after dissection, measured in relation to the axis formed between the metacarpophalangeal (MCP) joint of the thumb and the dorsal carpometacarpal joint (MC1-axis) and the axis formed between the second MCP joint and the distal edge of the trapezium (MC2-axis). RESULTS: The FPL does not follow the angle of the thumb metacarpal. The FPL runs ulnarly from the MC1-axis at a median of 32.5° in abduction and 30.6° in adduction. In relation to the MC2-axis, it runs at a median of 47.5° in abduction and 25° in adduction. CONCLUSIONS: The FPL tendon path can be preoperatively marked using: (1) the MC1-axis from which it runs ulnarly approximately at an angle of 30° in both abduction and adduction; or (2) the MC2-axis from which it runs radially at an angle of 47.5° in abduction and at an angle of 25° in adduction. We conclude that the FPL tendon path can be preoperatively marked using these axes and does not parallel the metacarpal axes of the thumb.

Clinical Examination of the Extensor Pollicis Brevis: Anatomical Study and Description of a Novel Clinical Sign.

BACKGROUND: The Extensor Pollicis Brevis (EPB) is an extrinsic thumb muscle whose main function is extension of the first metacarpophalangeal joint (MCPJ). It is subject to significant anatomical variation and may be absent, vestigial or have an anomalous distal attachment. Clinical examination of EPB is notoriously difficult and no reliable test has yet been described. We propose a novel test for the accurate examination of EPB. We sought to clarify the anatomical variations of EPB and to validate our clinical test using human cadaveric anatomical tests. METHODS: A structured literature review of all human cadaveric anatomical studies describing the attachments of EPB was performed using MEDLINE and Embase with the key words "Extensor Pollicis Brevis". A cadaveric anatomical study was performed using 18 unembalmed upper limbs. Positive and negative tests were simulated by manipulating the tendons of EPB, Extensor Pollicis Longus (EPL) and Flexor Pollicis Longus (FPL). Changes in tendon tension and joint position were measured and recorded. The EPB anatomy was then determined by dissection. RESULTS: Anatomical variations were present in the majority of wrists, with only 35% of EPB tendons having a distal attachment to the proximal phalanx alone. EPB was absent in 5% of specimens. There was a significant difference between the change in MCPJ position between a positive (36 degrees; 95% CI 25 to 47 degrees) and negative (19 degrees; 95% CI 14 to 25 degrees) clinical test (p = 0.002). CONCLUSIONS: The functional importance of EPB depends on its congenital architecture in addition to the functional demands of the patient. We report a novel clinical test which is effective in demonstrating the integrity of the EPB. A positive test result is observed when a change in MCPJ position that occurs while the interphalangeal joint is brought into flexion from full thumb extension is 25 degrees or more.

Management of posttraumatic finger contractures in adults.

This lecture will focus on posttraumatic finger contractures affecting the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints in adults. The pathophysiology, main causes and essential rehabilitation methods that can be used before resorting to surgical treatment are described, along with the clinical examination. The goal is to define the surgical indications, even though the literature shows the functional outcomes are disappointing. While there is little to no change in a joint's angular amplitude, the functional range of motion can be improved. There is practically no functional improvement except in cases of MCP extension contracture. For the PIP joint, the aim is to shift the range of motion into the functional range. Surgical approaches, surgical techniques and rehabilitation protocols are described in detail.

Immediate effects of an artificial change in hoof angulation on the dorsal metacarpophalangeal joint angle and cross-sectional areas of both flexor tendons.

Corrective shoeing is used to change hoof angulation with the intention to influence the angulation of the digital joints to reduce strain on associated tendons. The objective of this study is to examine how gradual changes in hoof angulation affect the dorsal metacarpophalangeal joint (DMPJ) angulation and cross-sectional areas (CSAs) of the deep digital flexor tendon (DDFT) and superficial digital flexor tendon (SDFT) concerning the individual toe conformation. Forelimbs of 30 horses were examined barefoot and equipped with 5°, 10° and 20° toe wedges (TWs) and heel wedges (HWs). Phalangeal angulation and lengths were measured in lateromedial radiographs of the digit. CSAs of both flexor tendons was calculated in sonographic images. Significant effects on the DMPJ and CSA of the DDFT/SDFT were measured with 10° and 20° HWs or 20° TWs. Both flexor tendons showed increasing CSA after heel elevation. Significant interindividual variations occurred. Phalangeal angulation and length influenced the responsivity of the parameters to a changed hoof angulation. Significant impact of corrective shoeing on the DMPJ and flexor tendons is related to a distinct change in hoof orientation and varies with individual toe conformation. Similar response of the DDFT and SDFT to raised and lowered hoof orientation needs further investigation for a more specific application of therapeutic shoeing.

Ultrasonography, computed tomography and magnetic resonance imaging of the bovine metacarpo/metatarsophalangeal joint.

The aims of the present study were to describe the normal ultrasonographic, magnetic resonance imaging (MRI) and computed tomographic (CT) appearances of the bovine metacarpo/metatarsophalangeal (MCP/MTP) joints and to assess the normal cross-sectional dimensions of the superficial (SDFT) and deep (DDFT) digital flexor tendons. A systematic ultrasound examination was performed on the MCP/MTP joints of 22 healthy cattle and two bovine cadavers, and the cross-sectional dimensions of the SDFT and DDFT were recorded. The cadaveric MCP/MTP joints (n=8) were scanned using a 16-slice multi-detector CT scanner and a 1.5 Tesla MRI scanner, injected with green latex and sectioned into transverse (n=4), sagittal (n=2) and dorsal (n=2) slices. Ultrasonographic, CT and MRI images were correlated with corresponding findings in anatomical dissections for the distal aspects of the third and fourth metacarpal/metatarsal bones, proximal aspects of the proximal phalanges, proximal sesamoid bones, lateral, common and medial digital extensor tendons, SDFT, DDFT, axial and abaxial collateral ligaments, suspensory, palmar/plantar, interdigital intersesamoidean and interdigital phalangosesamoidean ligaments, and collateral, cruciate and short sesamoidean ligaments. The axial and collateral sesamoidean ligaments could not be evaluated by ultrasonography. The articular cartilage, and the short and cruciate sesamoidean ligaments, were not identified in CT images. The cross-sectional dimensions of the SDFT and DDFT differed significantly between the forelimbs and hind limbs (P<0.05); there were no significant differences between the contralateral limbs. The annotated ultrasonographic, CT and MRI images are intended as a normal reference that could be useful for interpretation of clinical disease in the bovine MCP/MTP joint.

Intramuscular Tendon of the Adductor Pollicis and Underlying Capsule of the Metacarpophalangeal Joint: An Anatomical Study With Possible Implications for the Stener Lesion.

PURPOSE: To identify the layered relationship anatomically between the musculotendinous structures of the adductor pollicis, the ulnar collateral ligament, and the capsule of the metacarpophalangeal joint in terms of understanding the pathomechanism of a Stener lesion. METHODS: We macroscopically analyzed 37 cadaveric thumbs to identify the intramuscular tendon of the adductor pollicis and bony attachments of the joint capsule including the ulnar collateral ligament. In addition, we histologically analyzed 3 thumbs and made a 3-dimensional image of 3 other thumbs, using micro-computed tomography. RESULTS: The adductor pollicis has 3 components of an intramuscular tendon (dorsal, palmar, and distal), which connect to form a lambda shape. The dorsal part inserts into the joint capsule dorsal to the ulnar sesamoid. The palmar part inserts into the ulnar sesamoid. The distal part inserts into the lateral tubercle of the proximal phalanx. The thickened and cord-like part of the joint capsule, which has generally been referred to as the proper ulnar collateral ligament, has a distinct bony attachment on the proximal slope of the lateral tubercle of the proximal phalanx separate from the adductor pollicis insertion. CONCLUSIONS: Of the 3 components of the intramuscular tendon of the adductor pollicis muscle, the dorsal part inserted into not only the aponeurosis but also the joint capsule. CLINICAL RELEVANCE: The results of the current study suggest the anatomic basis for a possible pathomechanism of the Stener lesion.

Dorsal and Volar Surgical Approaches to the Metacarpophalangeal Joint: A Comparative Anatomic Study.

BACKGROUND: We compared 3 surgical approaches to the MP joint: a dorsal extensor tendon-splitting approach, a dorsal extensor tendon-reflecting parasagittal approach, and the volar A1 pulley approach. We quantitatively compared each of these approaches by measuring the amount of articular cartilage exposed on the base of the proximal phalanx. We hypothesize that visualization of the articular cartilage of the proximal phalangeal base is enhanced with the volar approach. METHODS: The MP joints of the 32 available digits were randomly assigned to 1 of 3 surgical approaches: extensor tendon splitting (A), extensor tendon reflecting (B), or volar approach (C). After each approach, the visible articular surface of the base of the proximal phalanx was stained with methylene blue. The MP joints were then disarticulated, and the proximal phalanges were digitally mapped using a 3-dimensional digitizer. Three-dimensional computer software was used to analyze and calculate the dyed exposed surface area and total surface area of each specimen. RESULTS: The mean % exposed joint surface area for the dorsal extensor splitting, dorsal extensor reflecting and volar approaches were 62%, 67% (over the dorsal side of the proximal phalanx) and 54% (over the volar side of the proximal phalanx), respectively. Multiple linear regression showed statistical significance for a smaller percentage of articular surface area exposed with the volar approach. However, this was not clinically significant. A significant association was found between location in the small finger and greater % exposed joint surface, compared to approaches in the index finger. In all volar approach specimens, the collateral insertion site was visible, but not in the dorsal approach specimens. CONCLUSIONS: Knowledge of the limits of each exposure is essential for planning the most appropriate surgical approach. The A1 pulley approach provided greater access to the volar 50% of the joint and collateral ligament insertion without violating the extensor mechanism. The amount of joint surface visualized through all 3 approaches was not significantly different. However, based on the accessibility to the collateral ligament insertion site among three different approaches, we recommend the volar A1 pulley approach for treatment of avulsion fractures of the base of the proximal phalanx. For other injuries of the MP joint, including the intra-articular proximal phalanx base fractures, and metacarpal head fractures, the dorsal approaches are still indicated.

Distance-based kinematics of the five-oblique-axis thumb model with intersecting axes at the metacarpophalangeal joint.

This paper proposes a novel and simple method to compute all possible solutions of the inverse kinematics problem of the five-oblique-axis thumb model with intersecting axes at the metacarpophalangeal joint. This thumb model is one of the suggested results by a magnetic-resonance-imaging-based study that, in contrast to those based on cadaver fingers or on the tracking of the surface of the fingers, takes into account muscle and ligament behaviors and avoids inaccuracies resulting from the movement of the skin with respect to the bones. The proposed distance-based inverse kinematics method eliminates the use of arbitrary reference frames as is usually required by standard approaches; this is relevant because the numerical conditioning of the resulting system of equations with such traditional approaches depends on the selected reference frames. Moreover, contrary to other parametrizations (e.g., Denavit-Hartenberg parameters), the suggested distance-based parameters for the thumb have a natural, human-understandable geometric meaning that makes them easier to be determined from any posture. These characteristics make the proposed approach of interest for those working in, for instance, measuring and modeling the movement of the human hand, developing rehabilitation devices such as orthoses and prostheses, or designing anthropomorphic robotic hands.

Vascular channels in metacarpophalangeal joints: a comparative histologic and high-resolution imaging study.

We evaluated whether cortical interruptions classified as vascular channel (VC) on high-resolution peripheral quantitative computed tomography (HR-pQCT) could be confirmed by histology. We subsequently evaluated the image characteristics of histologically identified VCs on matched single and multiplane HR-pQCT images. Four 3-mm thick portions in three anatomic metacarpophalangeal joint specimens were selected for histologic sectioning. First, VCs identified with HR-pQCT were examined for confirmation on histology. Second and independently, VCs identified by histology were matched to single and multiplane HR-pQCT images to assess for presence of cortical interruptions. Only one out of five cortical interruptions suggestive for VC on HR-pQCT could be confirmed on histology. In contrast, 52 VCs were identified by histology of which 39 (75%) could be classified as cortical interruption or periosteal excavation on matched single HR-pQCT slices. On multiplane HR-pQCT images, 11 (21%) showed a cortical interruption in at least two consecutive slices in two planes, 36 (69%) in at least one slice in two planes and five (10%) showed no cortical interruption. Substantially more VCs were present in histology sections than initially suggested by HR-pQCT. The small size and heterogeneous presentation, limit the identification as VC on HR-pQCT.

Incidence and anatomical distribution of hand tumours: a Singapore study.

INTRODUCTION: Hand tumours are frequently encountered in clinical practice. A list of differential diagnoses of the most common hand tumours based on anatomical location would be helpful for clinicians. We aimed to determine the anatomical distribution of hand tumours seen at a hand surgery practice in Singapore. METHODS: The medical records of 50 men and 65 women (mean age 41.7 [range 17-74] years) who underwent excision of hand tumours between 1 June 2010 and 31 December 2012 were reviewed. The histological diagnoses and anatomical locations of the tumours were analysed. The locations were divided into three main groups: (a) distal to the metacarpophalangeal joints (MCPJs); (b) between the MCPJs and carpometacarpal joints (CMCJs); and (c) between the CMCJs and the radiocarpal joint (RCJ). RESULTS: Overall, the most common tumours excised from the hand were ganglions (n = 66/116, 56.9%) and giant cell tumours of the tendon sheath (GCTTSs; n = 11/116, 9.5%). However, distal to the MCPJs, GCTTSs (n = 11/39, 28.2%) were more common than ganglions (n = 7/39, 17.9%). Most of the ganglions (n = 59/66, 89.4%) arose from between the CMCJs and RCJ. CONCLUSION: Most hand tumours were benign. Ganglions were the most common tumours between the CMCJs and RCJ, while GCTTSs were the most common tumours distal to the MCPJs.

Goniometrie evaluation of standing extension and maximum flexion joint angles of llamas and alpacas.

OBJECTIVE To determine and compare mean standing extension and maximum flexion angles of various joints in healthy adult alpacas and llamas, and determine the reliability of goniometric data within and between 2 observers for each joint of interest. SAMPLE 6 healthy adult llamas and 6 healthy adult alpacas. PROCEDURES The shoulder joint, elbow joint, carpal, and metacarpophalangeal (MCP) joints of the forelimbs and the hip joint, stifle joint, tarsal, and metatarsophalangeal (MTP) joints of the hind limbs were investigated. Each articulation was measured with a universal goniometer by 2 observers, who each obtained 2 measurements when each joint was maintained in standing extension and in maximal passive flexion. Two sample (unpaired) t tests were performed for comparisons of mean standing extension and maximum passive flexion angles between alpacas and llamas. Intraclass correlation coefficients were calculated for each articulation to assess interobserver and intra-observer reliability of measurements. RESULTS Llamas had larger mean standing extension angles than alpacas for the tarsal and elbow joint, but there were no significant differences between species for all other joints. For all joints, flexion measurements did not differ significantly between the 2 species. For most joints, the reliability of goniometric data between observers was good to excellent (intraclass correlation coefficients, 0.6 to 0.95) CONCLUSIONS AND CLINICAL RELEVANCE Except for the elbow joint and tarsus in extension, the angle of limb articulations during flexion and extension can be considered similar for alpacas and llamas. These measurements have relevance for veterinary surgeons when assessing joint mobility and conformation and determining appropriate angles for arthrodesis.

Assessing Finger Joint Biomechanics by Applying Equal Force to Flexor Tendons In Vitro Using a Novel Simultaneous Approach.

BACKGROUND: The flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) are critical for finger flexion. Although research has recently focused on these tendons' coactivity, their contributions in different tasks remain unclear. This study created a novel simultaneous approach to investigate the coactivity between the tendons and to clarify their contributions in different tasks. METHODS: Ten human cadaveric hands were mounted on our custom frame with the FDS and FDP of the third finger looped through a mechanical pulley connected to a force transducer. Joint range of motion, tendon excursion and loading force were recorded during individual joint motion and free joint movement from rest to maximal flexion. Each flexor tendon's moment arm was then calculated. RESULTS: In individual motions, we found that the FDP contributed more than the FDS in proximal interphalangeal (PIP) joint motion, with an overall slope of 1.34 and all FDP-to-FDS excursion (P/S) ratios greater than 1.0 with force increase. However, the FDP contributed less than the FDS in metacarpophalangeal (MCP) joint motion, with an overall slope of 0.95 and P/S ratios smaller than 1.0 throughout the whole motion except between 1.9% and 13.1% force. In free joint movement, the FDP played a greater role than the FDS, with an overall ratio of 1.37 and all P/S ratios greater than 1.0. CONCLUSIONS: The new findings include differences in finger performance and excursion amounts between the FDS and FDP throughout flexion. Such findings may provide the basis for new hand models and treatments.