Pointing in a different direction: a case of bilateral absence of extensor indicis.

Understanding anatomical variations as well as normal anatomy of the muscles and tendons of the hand is vital for successful clinical evaluation and surgery. A number of extensor muscle and tendon variations have been reported in the literature, including duplication, triplication, and absence. We report a rare anatomical variation that includes bilateral absence of the extensor indicis (EI) muscles and bilateral duplication of the extensor digitorum (ED) tendon to the second digit in the forearm of an 83-year-old male cadaver during routine upper limbs dissection. In the present case, only three muscles were present in the deep compartment: extensor pollicis longus (EPL), extensor pollicis brevis (EPB), and abductor pollicis longus (APL) with bilateral absence of EI. The reported prevalence of bilateral absence of EI muscle and tendon ranges from 0.5% to 3.5%. The prevalence of an additional index tendon arising bilaterally from the ED muscle belly is 3.2% of the population. Extension of the index finger is governed by the actions of EI and ED. However, the four tendons of ED are linked to each other by juncturae tendinum, restricting independent extension of the digits in certain postures, e.g. when the hand is fisted. With fisted hand, EI controls extension of the index finger. Clinically, EI tendons are used for tendon reconstruction procedures to restore function to the hand and thumb after trauma or tendon rupture. This report highlights the importance of anticipating anatomical variations and conducting pre-operative evaluations to confirm the presence of EI when planning tendon transfer procedures.

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.

Anatomic Considerations and Reconstruction of the Thumb Flexor Pulley System.

Disruption to the flexor pulley system of the thumb is an infrequent but devastating injury that can lead to significant compromise in both strength and function. Acute rupture leads to pain, weakness, reduced range of motion (ROM), and potential bowstringing of the flexor tendons. Conservative treatment with a pulley ring should be considered in all patients. However, failure of conservative treatment and bowstringing of the thumb are indications for operative intervention. Reconstruction of the oblique pulley system can be performed either in situ or using a free palmaris longus graft. Care should be taken to identify the neurovascular bundles to avoid compression during the reconstruction. Conscious sedation protocols augmented by ultrasound-guided sheath blocks allow the patient to actively and strongly contract the flexor pollicis longus tendon intraoperatively to appropriately tension the construct for optimal results. Rehabilitation should be performed in a stepwise manner beginning with early passive ROM, active ROM, and finally strengthening at around 8 weeks postoperative.

Single-Bundle vs Double-Bundle (Anatomical) Reconstruction of the Thumb Ulnar Collateral Ligament: Biomechanical Study.

Background: The goal of this study is to compare the biomechanical properties of anatomic (double-bundle) versus single-bundle reconstruction of the thumb metacarpophalangeal (MCP) joint ulnar collateral ligament (UCL) in a cadaveric model. Methods: Twelve fresh frozen cadaver hands were randomly assigned to single- or double-bundle reconstruction groups using a palmaris longus autograft and tenodesis screws. Two blinded examiners performed mechanical testing and measurements using fluoroscopic imaging. We evaluated MCP joint congruence and angle in the coronal plane at 0°, 30°, and 60° of flexion with valgus loads of 1.36 and 2.72 kg. Maximum MCP flexion and extension with a 0.45 kg load was also measured. Results: There was no significant difference between single- versus double-bundle reconstruction in ulnar congruence or MCP angle. With varying amounts of flexion, there was no significant difference in MCP valgus angle between the 2 techniques, suggesting comparable joint congruity and coronal MCP angle along the arc of thumb MCP motion. Conclusions: Single- and double-bundle UCL reconstructions of the thumb MCP joint have comparable biomechanical properties in regard to joint congruity under valgus load.

Adductor Pollicis Muscle Thickness for nutritional assessment: a systematic review / Espesura del Músculo Aductor del Pulgar para evaluación nutricional: una revisión sistemática / Espessura do Músculo Adutor do Polegar para avaliação nutricional: uma revisão sistemática

ABSTRACT Objective: The aim of this study is to systematically review the scientific findings about the efficacy of the measure of the Adductor Pollicis Muscle Thickness for nutritional assessment of individuals in various clinical conditions. Method: Systematic review study performed according to the methodology Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Results: 13 original articles published between 2004 and 2016 were included. The measure was associated/correlated to parameters of nutritional status (such as weight, body mass index and Global Subjective Assessment) and muscle mass markers (such as circumference brachial muscle circumference, brachial muscle area, calf circumference, and muscle mass). All these correlations were weak or moderate. Conclusion: The measurement can be used in different populations, being able to estimate nutritional status and muscle mass. However, it is suggested that it be used in a complementary way to the nutritional evaluation, not constituting a single diagnostic/monitoring parameter.

RESUMEN Objetivo: Revisar de forma sistemática las constataciones científicas acerca de la eficacia de la medida de la Espesura del Músculo Aductor del Pulgar para evaluación nutricional de los individuos bajo diversas condiciones clínicas. Método: Estudio de revisión sistemática, realizado conforme la metodología Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Resultados: Se incluyeron 13 artículos originales publicados entre 2004 y 2016. La medida se presentó asociada/correlacionada a los parámetros de evaluación del estado nutricional (peso, índice de masa corporal y Evaluación Subjetiva Global) y a los marcadores de masa muscular (como circunferencia braquial, circunferencia muscular braquial, área muscular braquial, circunferencia de la pantorrilla y masa muscular). Todas estas correlaciones fueron débiles o moderadas. Conclusión: La medida puede ser utilizada en diferentes poblaciones, siendo capaz de estimar el estado nutricional y la masa muscular. Sin embargo, se sugiere que se emplee de forma complementaria la evaluación nutricional, no constituyendo un parámetro único de diagnóstico/monitoreo.

RESUMO Objetivo: Revisar de forma sistemática as constatações científicas acerca da eficácia da medida da Espessura do Músculo Adutor do Polegar para avaliação nutricional de indivíduos em diversas condições clínicas. Método: Estudo de revisão sistemática, realizado conforme a metodologia PreferredReportingItems for SystematicReviewsand Meta-Analyses (PRISMA). Resultados: Foram incluídos 13 artigos originais publicados entre 2004 e 2016. A medida apresentou-se associada/correlacionada aos parâmetros de avaliação do estado nutricional (como peso, índice de massa corporal e Avaliação Subjetiva Global) e aos marcadores da massa muscular (como circunferência braquial, circunferência muscular braquial, área muscular braquial, circunferência da panturrilha e massa muscular). Todas essas correlações foram fracas ou moderadas. Conclusão: A medida pode ser utilizada em diferentes populações, sendo capaz de estimar o estado nutricional e a massa muscular. No entanto, sugere-se que seja empregada de modo complementar à avaliação nutricional, não constituindo um parâmetro único de diagnóstico/monitoramento.

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.

Ultrasonography could be used to predict extended insertion of the EPB tendon noninvasively.

INTRODUCTION: An abnormal distal insertion of the extensor pollicis brevis (EPB) tendon into the thumb interphalangeal joint (IP) has been observed in refractory cases of de Quervain's disease. This is associated with the extensor being wider at the midpoint of the proximal phalanx; however, there is no method to noninvasively measure this. This study evaluated the accuracy of measuring the extensor width using ultrasonography, to establish a noninvasive method for predicting an EPB extending the IP insertion. MATERIALS AND METHODS: Of 23 arms from 12 fresh frozen cadavers, the extensor tendon width at the midpoint of the proximal phalanx was measured using ultrasonography and directly at dissection. The association between these values was evaluated using correlation analysis. A cut-off value of extensor tendon width was obtained using receiver operating characteristic analysis. RESULTS: A strong correlation was observed between the ultrasonography and the measured values. The EPB tendons were normal in 13 arms (57%) and extended in 10 (43%), with a significant difference between these groups in the mean width of the extensor tendon (6.8 ± 1.1 vs. 8.4 ± 1.0 mm). A cut-off extensor tendon width of 8.0 mm yielded an EPB extending the IP. CONCLUSION: An EPB extending the IP tendon can be predicted by measuring the extensor tendon width at the midpoint of the proximal phalanx using ultrasonography. The cut-off tendon width value of ≥ 8.0 mm may be useful for assessments prior to surgery and for conservative care.

Topographic anatomical landmarks for pulley system of the thumb.

PURPOSE: Knowledge of anatomical landmark to pulley system of the thumb is essential in successful treatment of trigger thumb release either by percutaneous or by minimally invasive technique. Though surgical release of trigger thumb is done commonly, there is paucity of data in the literature regarding its surface landmarks. The purpose of this study is to identify palmar surface anatomical landmarks to the pulley system of the thumb. METHODS: Dissection was performed on 55 fresh frozen adult cadaveric thumbs. The palmar thumb creases were given names as the proximal-proximal crease (PPC) present at the metacarpophalangeal joint, the distal-proximal crease (DPC) over the middle of the proximal phalanx and the distal crease (DC) at interphalangeal joint. The distance between the proximal edges of each pulley to the three thumb creases and longitudinal length of A1, A2, oblique and Av pulley was measured using digital vernier caliper and was expressed in mean and standard deviation. RESULTS: The proximal edge of A1 pulley was 1.98 ± 1.61 mm proximal to the PPC. The mean longitudinal length of the A1 pulley was measured to be 5.06 ± 0.87 mm, so the distal edge of the A1 pulley was calculated to lie 3.08 mm distal to PPC. The proximal edge of Av and oblique pulley was situated 7.78 ± 2.5 and 15.72 ± 3.22 mm distal to PPC, respectively. The proximal edge of A2 pulley was very nearer and 2.88 ± 1.79 mm proximal to DC. CONCLUSION: The knowledge of anatomical skin surface landmarks is helpful in the percutaneous release or minimally invasive procedure. The PPC serves as a definite landmark for A1, Av and oblique pulley whereas it is the DC for A2 pulley.

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.

The Dorsal Aponeurosis of the Thumb.

PURPOSE: To evaluate the thumb dorsal aponeurosis anatomy. Consideration of structural differences between the fingers and thumb will provide an improved clinical understanding of the thumb dorsal aponeurosis anatomy. METHODS: Ten fresh cadaver hands from 5 patients with an average age of 31.6 (range, 22-41) years were dissected. The thenar muscles were identified and insertion sites were documented. The fibers of the dorsal aponeurosis and contributions were identified. RESULTS: The flexor pollicis brevis superficial head contributed to the radial fibers of the dorsal aponeurosis in 8 specimens and contributed to the deep head in 1 specimen. The abductor pollicis brevis provided fibers to the radial dorsal aponeurosis in all 10 specimens. The oblique and transverse heads of the adductor pollicis contributed to the ulnar dorsal aponeurosis in 8 and 9 hands, respectively. The fibers of the intrinsic apparatus were composed of 3 major types: transverse, oblique, and long. CONCLUSIONS: This investigation provides a detailed anatomic study of the dorsal aponeurosis of the thumb with observation of both intrinsic and extrinsic contributions. CLINICAL RELEVANCE: Understanding the anatomy of the dorsal aponeurosis of the thumb remains important not only for evaluation of the classic Stener lesion, but also for the appropriate treatment of deformity, contracture, and neuromuscular disorders involving the thumb.

Functional pectoralis minor myocutaneous flap transplantation for reconstruction of thumb opposition: An anatomic study with clinical applications.

OBJECTIVE: To develop a myocutaneous flap for reconstruction of thumb opposition function in patients with loss of the thenar muscles and skin. METHODS: An anatomic experiment on the dimensions of the pectoralis minor muscle and its neurovascular supply in 10 adult human cadavers was conducted to evaluate the feasibility of microsurgical transplantation using part of the muscle for thumb opposition reconstruction. Based on these results, we performed surgical thenar reconstruction with a pectoralis minor myocutaneous flap in seven patients (34.7 ± 9.8 years of age) from December 2007 to October 2010. RESULTS: The transferred muscle was reinnervated with the third lumbrical branch of the ulnar nerve. Six to twelve months after the surgery, follow-up assessment showed that all patients had recovered functional opposition of the carpometacarpal joint with survival of the skin and a muscle power of M4 to M5. CONCLUSION: Our results support the use of this new technique for thenar and opposition reconstruction in patients with severe loss of the thenar muscles and skin and damage to the median nerve and who wish to improve the appearance of the thenar eminence.

Características histológicas de la piel de la cara volar del pulgar en individuos chilenos con desvanecimiento del dactilograma / Histological characteristics of the skin of the volar side of the thumb in Chilean individuals with vanishing dactylogram

En forma característica, la piel de manos y de pies presenta un diseño morfológico particular denominado dactilograma. Este patrón es característico de la piel gruesa de dígitos, palma de manos y plantas de pies y sus propiedades le permiten cumplir un rol protagónico en la identificación humana. No se han descrito los cambios que ocurren en la cara volar de pulgar debido al proceso de envejecimiento. Es por esta razón que el objetivo del presente trabajo fue evidenciar los cambios en la bioestructura de la piel de la cara volar del primer dígito de la mano derecha en individuos de edad avanzada. Para este estudio se utilizaron muestras de piel de pulgar derecho de individuos chilenos de ambos sexos y de edad avanzada. Estas muestras fueron sometidas a estudio histológico con H-E, Tricromico de Mallory, Rojo Sirio de Junquiera, Reaccion de PAS y tinción de Orceina. Las observaciones y registros se realizaron con Microscopio Zeiss Axiostar Plus, cámara fotográfica Canon modelo PowerShot A 640 y software Image Tool 3.0 UTHSCSA, 2002. Los resultados evidenciaron cambios significativos en el grosor de la epidermis, en la morfología de la membrana basal, en la forma y cantidad de vasos sanguíneos, en la distribución y patrón de ordenamiento de las fibras elásticas y colágenas y en el aumento de corpúsculos táctiles. Estos cambios confirman la existencia de cambios histológicos importantes debido al proceso de envejecimiento, lo que podría ser determinante en el paulatino desvanecimiento de las características morfológicas del dactilograma, dificultando observar, evidenciar y registrar el dactilograma en individuos de edad avanzada, disminuyendo la posibilidad de identificación de estos individuos, acarreando posibles consecuencias médico-legales.

Characteristically the skin of hands and feet shows a particular morphological design called dactylogram. This pattern is typically on the thick skin of the digits, the palm of the hands and the soles of the feet, and its properties have a leading role in human identification. The changes that take place on the volar side of the thumb due to the aging process have not yet been described. It is for this reason that the objective of the present work is to show the variation of the biostructure on the skin of the volar side of the first digit of the right hand in elderly individuals. For this research, skin samples of the right thumb from elderly Chilean subjects of both sexes were used. These samples underwent histological studies with H & E, Mallory´s trichrome, Sirio of Junqueira Red, PAS Reaction and Orcein staining. The observation and records were made with Zeiss Axiostar Plus Microscope, a Canon PowerShot A 640 camera, and Image Tool 3.0 software UTHSCSA, 2002. The results showed significant changes on the epidermis thickness, in the basement membrane morphology, in the shape and quantity of blood vessels, the distribution and arrangement pattern of the collagen and elastic fibers, and in the increase of tactile corpuscles. These changes confirm the existence of significant histological changes due to the aging process, which could be decisive in the gradual fading of the morphological characteristics of the dactylogram, making it difficult to observe, demonstrate and record the dactylogram on individuals of advanced age which reduces the possibility of identification of those individuals, leading to possible medical-legal consequences.

Thickness of the adductor pollicis muscle in nutritional assessment of surgical patients.

OBJECTIVE: To evaluate the correlation between thickness of the muscle adductor pollicis and anthropometric measurements, body mass index and Subjective Global Assessment in the nutritional assessment of surgical patients. METHODS: The study population comprised patients admitted to the general and reconstructive surgery unit of a university hospital in the city of Vitória (ES), Brazil. The inclusion criteria were patients evaluated in the first 48 hours of admission, aged ≥20 years, hemodynamically stable, with no edema or ascites. Data analysis was performed using the software Statistical Package for Social Science 21.0, significance level of 5%. RESULTS: The sample consisted of 150 patients that were candidates to surgery, mean age of 42.7±12.0 years. The most common reasons for hospitalization were surgical procedures, gastrintestinal diseases and neoplasm. Significant association was observed between thickness of adductor pollicis muscle and Subjective Global Assessment (p=0.021) and body mass index (p=0.008) for nutritional risk. Significant correlation was found between thickness of adductor pollicis muscle and arm muscle circumference, corrected arm muscle area, calf circumference and body mass index. There were no significant correlations between thickness of adductor pollicis muscle and triceps skinfold and age. CONCLUSION: The use of thickness of adductor pollicis muscle proved to be an efficient method to detect malnutrition in surgical patients and it should be added to the screening process of hospitalized patients, since it is easy to perform, inexpensive and noninvasive.

Thickness of the adductor pollicis muscle in nutritional assessment of surgical patients / Espessura do músculo adutor do polegar na avaliação nutricional de pacientes cirúrgicos

ABSTRACT Objective To evaluate the correlation between thickness of the muscle adductor pollicis and anthropometric measurements, body mass index and Subjective Global Assessment in the nutritional assessment of surgical patients. Methods The study population comprised patients admitted to the general and reconstructive surgery unit of a university hospital in the city of Vitória (ES), Brazil. The inclusion criteria were patients evaluated in the first 48 hours of admission, aged ≥20 years, hemodynamically stable, with no edema or ascites. Data analysis was performed using the software Statistical Package for Social Science 21.0, significance level of 5%. Results The sample consisted of 150 patients that were candidates to surgery, mean age of 42.7±12.0 years. The most common reasons for hospitalization were surgical procedures, gastrintestinal diseases and neoplasm. Significant association was observed between thickness of adductor pollicis muscle and Subjective Global Assessment (p=0.021) and body mass index (p=0.008) for nutritional risk. Significant correlation was found between thickness of adductor pollicis muscle and arm muscle circumference, corrected arm muscle area, calf circumference and body mass index. There were no significant correlations between thickness of adductor pollicis muscle and triceps skinfold and age. Conclusion The use of thickness of adductor pollicis muscle proved to be an efficient method to detect malnutrition in surgical patients and it should be added to the screening process of hospitalized patients, since it is easy to perform, inexpensive and noninvasive.

RESUMO Objetivo Avaliar a correlação entre a medida da espessura do músculo adutor do polegar com medidas antropométricas, índice de massa corporal e Avaliação Subjetiva Global no diagnóstico nutricional de pacientes cirúrgicos. Métodos Participaram do estudo pacientes internados em uma unidade de cirurgia geral e reparadora de um hospital universitário de Vitória (ES), Brasil. Os critérios de inclusão foram pacientes avaliados nas primeiras 48 horas de internação, idade ≥20 anos hemodinamicamente estáveis, sem edema ou ascite. A análise dos dados foi realizada pelo softwareStatistical Package for Social Science, versão 21.0, com nível de significância de 5%. Resultados Compuseram a amostra 150 pacientes candidatos à cirurgia, com média de idade de 42,7±12,0 anos. Os motivos de internação mais comuns foram procedimentos cirúrgicos, doenças do trato gastrointestinal e neoplasias. Observou-se associação significativa entre a espessura do músculo adutor do polegar com a Avaliação Subjetiva Global (p=0,021) e com o índice de massa corporal para risco nutricional (p=0,008). Foram encontradas correlações significativas entre a espessura do músculo adutor do polegar com circunferência muscular do braço, área muscular do braço corrigida, circunferência da panturrilha e índice de massa corporal. Não foram encontradas correlações significativas entre a espessura do músculo adutor do polegar com prega cutânea triciptal e idade. Conclusão O uso da espessura do músculo adutor do polegar mostrou-se um método eficiente na detecção de desnutrição em pacientes cirúrgicos e deve ser acrescentado ao processo de triagem de pacientes hospitalizados, uma vez que é de fácil execução, baixo custo e não invasivo.

Thumb ligament injuries.

Thumb ligament injuries are common, particularly those involving the metacarpophalangeal joint. Our understanding and treatment of these injuries continues to evolve. This article provides a comprehensive review of recent literature with updates pertaining to the anatomy, function, diagnosis, and treatment of thumb ligament injuries.

Estudio anatómico del fascículo accesorio del músculo flexor largo del pulgar y su relación con el nervio interóseo anterior en individuos brasileños / Anatomical study of the accessory head of the flexor pollicis longus muscle and its relationship to the anterior interosseous nerve in Brazilian individuals

Entre los síndromes de compresión nerviosa en el antebrazo, debido a la presencia de arcos tendinosos de músculos relacionados al trayecto de los nervios que transcurren entre sus capas musculares, se encuentra el del nervio interóseo anterior (NIA). La presencia de variaciones musculares puede generar arcos que ocasionan compresión nerviosa. El objetivo fue establecer la incidencia y morfología del músculo accesorio del flexor largo del pulgar (AFLP) y la relación de éste con el NIA o sus ramos motores. Se utilizaron 30 antebrazos, de cadáveres formolizados de individuos adultos brasileños. El punto de referencia seleccionado para las mediciones fue el epicóndilo medial del humero (EMH). Se observó que tres miembros superiores presentaron el AFLP (10%), en todos ellos se originó en el EMH para terminar insertándose en el tendón del músculo flexor largo del pulgar (FLP). El vientre muscular presentó aspecto fusiforme, el cual tenía un tendón que formó un arco con el FLP. En uno de los casos, este arco se relacionó con el paso del NIA; en los otros dos, lo hizo con los ramos motores que se originan del NIA. Al diagnosticar los síndromes generados por compresión nerviosa se debe considerar la presencia del AFLP, el cual, potencialmente se puede relacionar con el trayecto del NIA o de sus ramos.

Between the syndromes of nerve compression in the forearm, due to the presence of the tendinous arches related to the nerves that pass between its muscle layers, is the anterior interosseous nerve (AIN). The presence of muscular variations can generate arches that cause nerve compression. The aim of our study was to establish the incidence and morphology of the accessory head of flexor pollicis longus muscle (AFPLm) and its relationship with AIN or its branches. Thirty forearms of formalized corpses of adult Brazilians were used. The selected landmark for measurements was the medial epicondyle of the humerus (MEH). It was noted that three upper limbs presented the AFPLm (10%), originated from the MEH to end inserted into the tendon of the flexor pollicis longus muscle. The AFPLm showed fusiform appearance, which had a tendon that formed an arch with the flexor pollicis longus muscle. In one case, this arch was associated with the passage of AIN. In the other two, this arch was related to motor branches originating from the AIN. The diagnosis of nerve compression syndromes should consider the presence of AFLPm, which potentially can be related to the course of the AIN or its branches.

Anatomy of the extensor pollicis brevis associated with an extension mechanism of the thumb metacarpophalangeal joint.

This study aimed to determine whether the extensor pollicis longus (EPL) or abductor pollicis longus (APL) can replace the function of thumb extension in hands in which the extensor pollicis brevis (EPB) is absent. Cadaver dissection was performed to examine anatomical association between the interphalangeal (IP) joint and metacarpophalangeal (MP) joint of the thumb, as well as extension mechanism in clinical cases. EPB insertion could be classified into eight types, and the EPB was absent in 7.6% of all cases. In hands without an EPB, the width of the EPL tendon tended to be wider, and the number of APL tendons was significantly greater than in hands with an EPB. In hands without an EPB, the EPL and APL may replace the function of the EPB. As a result, a greater load is imposed on these two tendons than in hands with the EPB.

Dorsoradial ligament imbrication for thumb carpometacarpal joint instability.

UNLABELLED: Dorsoradial ligament imbrication is a direct and effective alternative to ligament reconstruction or metacarpal osteotomy in patients with symptomatic thumb carpometacarpal (CMC) joint instability. This procedure is performed by imbricating either the trapezial or the metacarpal attachment of the dorsoradial ligament with the use of a suture anchor. The procedure is indicated in the setting of chronic hyperlaxity or instability of the thumb CMC joint. Significant arthritic changes in the thumb CMC joint are a contraindication for this procedure. We present our technique along with an anatomic dissection to demonstrate the ligament and surgical procedure on an anatomic specimen. We also present results from 3 patients who underwent this technique with images and clinical results for 3 patients with long-term follow-up. LEVEL OF EVIDENCE: Level IV-Therapeutic.

Hand surface landmarks and measurements in the treatment of trigger thumb.

PURPOSE: To determine hand surface landmarks and measurements that may be useful in localizing the A1 pulley and digital neurovascular structures in the treatment of trigger thumb. METHODS: We highlighted 4 surface landmarks in 20 adult cadaveric hands: the radial border of the index finger, the ulnar border of the thumb, the thumb interphalangeal joint flexion creases, and the thumb metacarpophalangeal joint creases. We injected the radial arteries with red latex and dissected the thumbs. RESULTS: The proximal margin of the A1 pulley was located an average of 0.3 mm proximal (range, 3.2 mm proximal to 2.3 mm distal) to the most proximal metacarpophalangeal joint flexion crease. The ratio of measurements from the thumb tip to the midpoint of the interphalangeal joint flexion creases and from this point to the proximal margin of the A1 pulley averaged 1.1:1. The radial digital nerve crossed obliquely over the flexor pollicis longus tendon and approached the proximal margin of the A1 pulley at a mean distance of 2.7 mm (range, 0-12.9 mm). The ulnar digital nerve was located deep to intersecting lines drawn along the radial border of the index finger and the ulnar border of the thumb and coursed parallel to the A1 pulley at a mean distance of 5.4 mm (range, 0-11.1 mm). At the level of the A1 pulley, the digital arteries were positioned dorsal to the digital nerves, and both nerves were located 1.0 to 4.2 mm from the skin surface. CONCLUSIONS: The findings from our study clarify hand surface landmarks in localizing the thumb A1 pulley and digital neurovascular structures. CLINICAL RELEVANCE: Awareness of topographical landmarks in localizing the A1 pulley and digital neurovascular structures and the relationships between the digital neurovascular structures and the A1 pulley may improve the safety and efficacy of trigger thumb treatment.

The thumb carpometacarpal joint: anatomy, hormones, and biomechanics.

Although there are many surgical options to treat thumb carpometacarpal (CMC) arthritis, a precise etiology for this common disorder remains obscure. To better understand the physiology of the thumb CMC joint and treat pathology, it is helpful to examine the biomechanics, hormonal influences, and available surgical treatment options, along with the evolutionary roots of the thumb; its form and function, its functional demands; and the role of supporting ligaments based on their location, stability, and ultrastructure. It is important to appreciate the micromotion of a saddle joint and the role that sex, age, and reproductive hormones play in influencing laxity and joint disease. Minimally invasive surgery is now challenging prevailing treatment principles of ligament reconstruction and plays a role in thumb CMC joint procedures.