Anomalous extensor muscles of the hand: a review

Variations in the Extensor Pollicis Brevis-Extensor Pollicis Longus Tendon Complex

Despite several reports on the running of the extensor pollicis brevis (EPB) tendons, the classification of tendon insertions remains ununified due to differences in reports. This diversity in tendon patterning is attributed to the process of tendon development. In this study, we assessed the running of the EPB tendons of 44 cadaver hands fixed in ethanol/formalin in detail and examined the existing classification method. The specimens were obtained from 15 women and seven men, with an average age of 86 years. Consistent with previous reports, we observed a wide diversity in the running of the EPB tendons. Further, we found that EPB tendon insertions showed diverse variations in the proportion and running of fibers, making it difficult to classify them into independent patterns. It is speculated that the EPB tendon develops through a different process than that of the muscle body of the EPB and that the entire muscle-tendon module of the EPB is evolving. The diversity of the EPB tendons observed in this study may reflect the ongoing process of evolution. In clinical practice, a wide variation in the running of the EPB tendons should be considered.

Extensor Medii Proprius: A Cadaveric Case Report

During routine dissection of 11 cadavers that originated with the Body Donor Program at Philadelphia College of Osteopathic Medicine (PCOM) Georgia, a 69-year-old African American male with bilateral extensor anomalies in the dorsal forearm compartment was encountered. The distinct muscle belly, identified as the extensor medii proprius (EMP), originated from the distal ulna and was inserted near the dorsal aponeurosis of the third digit. Manual traction of the right EMP tendon resulted in the extension of the third digit, suggesting the functional significance of the anomalous muscle. This case study analyzes the EMP found during dissection, as well as the anomalous muscle's prevalence, embryologic origin, and clinical relevance. The presence of the EMP muscle and tendon can be considered when assessing pain in the dorsum of the hand and when preparing for surgical repair or tendon transfer.

Anomalous Extensor Digiti Minimi with Multiple Slips and Bulbous Appearance

The extensor digiti minimi is a muscle in the posterior compartment of the forearm that extends the fifth digit. Variations of the extensor tendons of the hand are common and mostly asymptomatic, however, some may impinge and occupy the narrow dorsal compartments of the wrist causing dorsal wrist pain and impairment of digital movement. Orthopedic literature illustrates how frequent anomalies of the extensor indicis proprius, extensor digitorum brevis manus, and extensor medii proprius occur; however, minimal literature documents a bulbous, multi slip extensor digiti minimi. Within this case, a 30-year-old, right-handed woman with no prior hand trauma presented with recurrent snapping localized to her right fifth digit, causing intermittent pain and an audible "click". This study aims to provide a thorough anatomical description of a rare extensor digit minimi anomaly and a viable option to treat successfully an inflamed, symptomatic extensor retinaculum affecting the extensor digiti minimi.

Soft Tissue Benign Hand Masses in the First Web Space: A Retrospective Case Series

INTRODUCTION

Hand masses are fairly common. While most of these masses are either ganglion cysts or benign tumors, masses in the first web space are not rare, and they may in fact represent a variety of lesions. These include both benign and malignant tumors, metastases, or congenital and anomalous structures, and may involve nerves, vascular structures, connective tissue, and joints.

METHODS

In this retrospective case series, data on 12 cases of first dorsal web space hand mass treated at our center over a period of five years were collected and analyzed.

RESULTS

 Twelve consecutive patients presenting with a first dorsal web space hand mass over a period of five years were reviewed. This represented a group of nine females and three males, with a mean age of 53 years (range = 16-70 years). Seven patients had a mass on the right side and five on the left side. The surgical approach to resect the mass in all 12 patients was dorsal. The most common diagnosis was ganglion cyst (50%), followed by lipoma (25%) and aneurysm (16.6%). There was one case of eccrine spiradenoma.

CONCLUSION

First dorsal web space hand masses can encompass multiple different pathologies, and the first web space has an intricate anatomy. Both of these factors mandate a careful approach that includes meticulous preoperative planning with appropriate advanced imaging studies, which helps to make the surgical procedure more efficient and accurate.

Anomalous Extensor Indicis Proprius Muscle Extending Beyond the Extensor Retinaculum: A Case Report

CASE

During dissection of the upper limb of a cadaver in preparation for a first-year anatomy course, an extensor indicis proprius (EIP) variant was discovered with its muscle belly extending distal to the extensor retinaculum and beyond what has been previously described in the literature.

CONCLUSION

EIP is commonly used as a tendon transfer for extensor pollicis longus rupture. Few anatomic variants of EIP have been reported in the literature, but such variants should be considered because of their consequences to the success of tendon transfer and potential implications for diagnosis of an otherwise unexplained mass of the wrist.

Middorsal Wrist Pain in the High-Level Athlete: Causes, Treatment, and Early Return to Play

Wrist injuries in the competitive athlete are a common reason for evaluation related to an acute injury or after symptoms have become chronic. While radius- and ulna-sided wrist pain are common topics covered in the literature, middorsal wrist pain is more common than the available literature would suggest. Missed diagnoses and inadequate treatment can significantly increase athlete morbidity and delay return to play. The goal of this article was to review the differential diagnosis of middorsal wrist pain in the athlete and discuss the diagnosis, treatment, and early return to play for each condition.

Biomechanical analysis of the effect of the finger extensor mechanism on hand grasping performance

Quantifying the effect of routing and topology of the inter-connected finger extensor mechanism on hand grasping performances is a long-standing research problem for the better clinical diagnosis, surgical planning and biomimetic hand development. However, it is technically demanding to measure the hand performance parameters such as the contact forces and contact area during hand manipulation. It is also difficult to replicate human hand performance through the physical hand model due to its sophisticated musculotendinous structure. In this study, an experimental validated subject-specific finite element (FE) human hand model was used for the first time to quantify the influence of different tendon topologies and material properties on hand grasping quality. It is found that the grasping quality is reduced by 15.94% and 8.54% if there are no extensor hood and lateral band respectively, and the former plays a more important role in transmitting forces and maintaining grasping qualities than the latter. Excluding extensor hood in the topology causes more reductions in hand contact pressure and contact area than omitting lateral band. 7.5% of the grasping quality is lost due to a softened tendon with half of its original Young's Modulus. Hardened extensor tendon does increase the grasping quality, but the enhancing effect tends to level off once the tendon Young's Modulus is increased by more than 50%. These results prove that the lateral band and extensor hood are critical components for maintaining grasping quality. The dexterity and grasping quality of robotic and prosthetic hands could be improved by integrating these two components. There is also no need to use very stiff tendon material as it won't help to effectively enhance the grasping quality.

Accessory extensor pollicis longus tendon in emergency surgery

Background

A true accessory extensor tendon of the thumb seems to be rare. We found a variation of the accessory extensor pollicis longus (EPL) tendon while performing an emergency surgical procedure. Identification of this accessory tendon during emergency surgery has not been previously reported.

Case presentation: A 43-year-old man presented to our hospital after sustaining a work-related injury involving a saw. During the operation, the tendons of the EPL, accessory EPL, and extensor pollicis brevis were severed. The lacerated tendon and tendon sheath were repaired, and the wrist and thumb were positioned in extension. The patient’s postoperative activity returned to normal without the need for a second tendon release operation.

Conclusions

Surgeons should be aware of this anatomic anomaly of the EPL tendon. Presentation of our case increases clinicians’ chances of preoperatively detecting this anomaly, which can improve surgical outcomes.

Extensor Digitorum Brevis Manus presenting as a symptomatic lump on the dorsum of the hand

Lumps in the hand are a common presenting complaint in General Practice. We present the case of a 24-year-old male who presented to his General Practitioner with a painful lump in the dorsum of his right hand. He was referred to the sarcoma services where MRI and ultrasound examinations revealed an accessory Extensor Digitorum Brevis Manus muscle as the cause of the patient's symptoms. When patients present with a painful or discomforting lump in the dorsum of the hand during or after repetitive use, typically on flexion, a diagnosis of Extensor Digitorum Brevis Manus should be considered.

Accessory extensor pollicis longus: A rare tendon anomaly

This report provides a complete review of a rare anatomical variation, the accessory extensor pollicis longus (EPL) tendon and its clinical significance. We will describe a case of an asymptomatic accessory EPL that was found incidentally during surgery with a tendon located in the fourth extensor compartment. Pulling on it induced extension of the thumb interphalangeal joint. Very few cases of accessory EPL have been previously reported with various muscle origins and tendon insertions. In the literature, three symptomatic cases of accessory EPL were reported with a tendon running in a compartment other than the fourth. Although this variation is asymptomatic in most cases, knowledge of its existence might be useful in routine procedures to avoid inadvertent tendon damage, or during tendon repair.

Variant course of extensor pollicis longus tendon in the second wrist extensor compartment

Among the muscles involved in thumb movement, the extensor pollicis longus (EPL) tendon of the hand is considered the most consistent structure with the least variation among individuals. There have been a few reports regarding different types of supernumerary tendons; however, an abnormal course of the EPL tendon is extremely rare. We describe a case of a variant course of a single EPL tendon appearing in the second extensor compartment of the wrist. This case was observed incidentally during wrist surgery, and demonstrates a unique variation of tendon course, which has not been reported previously. The knowledge of this anatomic variation is helpful in surgical planning and for making accurate diagnoses.

Anomalous extensor tendons to the long finger: a cadaveric study of incidence

PURPOSE

To evaluate the incidence and anatomic insertion sites of extensor medii proprius and extensor indicis medii communis tendons to the long finger in cadaveric dissection and to describe the insertion of the extensor medii proprius.

METHODS

Thirty randomly selected adult cadavers, 44 upper extremities, were examined for the presence or absence of an anomalous extensor tendon to the long finger. If present, tendon origin and insertion sites were documented, and the width of the tendon was evaluated.

RESULTS

The extensor medii proprius was observed in 4 of 44 extremities, an incidence of 9%. The extensor indicis medii communis was observed in 7 of 44 extremities, an incidence of 16%. Tendon widths for both the extensor medii proprius and extensor indicis medii communis specimens ranged from 1.5 to 3.0 mm.

CONCLUSIONS

The incidence of an anomalous slip of tendon to the long finger might be higher than previously reported, with a combined incidence of 25% in this cadaveric study. This anomalous slip can be a resource for surgical reconstruction.

CLINICAL RELEVANCE

The presence of anomalous tendinous slips to the long finger can be easily overlooked. Understanding the anatomical relationships, incidence, and donor tendon availability of these anomalous tendons might aid with surgical planning.

Anomalous presentation of flexor carpi radialis brevis: a report of six cases

An anomalous presentation of flexor carpi radialis brevis (FCRB) is reported in six patients. These findings occurred in a consecutive series of 172 distal radius fracture fixations using a volar approach between 2002 and 2007. This is the first report of this anomalous muscle from a clinical series.

Accessory extensor pollicis longus

Phylogenetically the accessory extensor pollicis longus in man seems to find its origin in the deep extensor layer, and this has largely been described in primates. I describe a case and present a comprehensive review of other publications on the subject.

Incidence of extensor digitorum brevis manus muscle

The extensor digitorum brevis manus, a supernumerary muscle in the fourth extensor compartment of the dorsum of the wrist, is a relatively rare anomalous muscle. Extensor digitorum brevis should be included in the differential diagnosis of soft tissue masses on the dorsal aspect of the hand as it may mimic cystic, neoplastic, inflammatory, and infectious masses arising in the dorsum of the wrist. Seventy-two upper limbs of male and female cadavers were dissected and examined to study the pattern of extensor tendons of the index finger. In the present study, we observed three cases (4.2%) of the extensor digitorum brevis manus on the left side. In one cadaver (0.72%), there was an additional tendon arising from the extensor indices which was inserted to the radial side of the dorsal digital expansion of the index finger. The extensor digitorum brevis manus muscle (EDBM), an anatomic variant of the extensor muscle of the dorsum of the hand, is found in approximately 2% to 3% of the population. This variation is, therefore, clinically and surgically relevant because the EDBM may be the only muscle responsible for the independent extension of the second digit. The aim of the present study is to report the incidences of this muscle thereby creating awareness of its existence and of its characteristic appearance to surgeons.

Snapping wrist due to an anomalous extensor indicis proprius: a case report

Variation in the extensor muscles of the hand is common. These anatomic deviations are rarely symptomatic. We report a unique case of an anomalous extensor indicis proprius causing a painful snapping wrist. Intraoperative examination revealed a disproportionately large muscle belly under the extensor retinaculum causing subluxation of the ring and small extensor tendons creating a painful snapping phenomenon. Following excision, the subluxation and pain resolved.

A case of bilateral extensor digitorum brevis manus

We report a case of symptomatic dorsal mass in a 72-year-old man, with onset of pain during daily life efforts. On the other side, the dominant hand, a similar mass without any impairment was present. Before surgery, the mass on the left nondominant wrist was diagnosed by ultrasound as synovial ganglion: during excision, a muscular belly was found and sent to isthological evaluation, confirming the existence of an alive aberrant muscular tissue, named Extensor Digitorum Brevis Manus. Being reported in literature as occasionally bilateral, we decided to perform, 3 months later, an MRI in the contralateral asymptomatic wrist: it was possible to reveal the presence of a similar but asymptomatic mass.

Anatomo-histological analysis of the juncturae and their relations to the extensor tendons to the dorsum of the hand

The juncturae tendinum (JT) may coordinate the extension of hand, force redistribution and the stabilization of the metacarpophalangeal joint. The JT were studied for their gross appearance, shape, thickness, location and histological examination with the dorsum of the hand in 54 cadavers. The JT were identified into three groups according to their anatomo-histological features. The type 1 was observed in 57.4% of the cases in the second IMC and in 16.7% of the cases in the third IMC. The type 2 was detected in 3.7% of the cases in the second IMC and in 59.3% of the cases in the third IMC space. The type of 3Y was accounted for 14.8% JT in the third IMC space and 53.7% JT in the fourth space. The type of 3r was found in 5.55% of the cases in the third IMC and in 37% of the cases in the fourth IMC space. In the histologic examination, the fibers of types 1 and 2 JTs were straight. Type 3 JTs were composed of regularly oriented parallel and crosswise bundles of tendineous tissue. This study is important in terms of giving accurate knowledge on the anatomo-histological analysis of the JTs and their relations to the extensor tendons to the dorsum of the hand. An understanding of the structures of the JTs and the interactions between the tendons of the fingers is of utmost importance in hand assessment, during the reconstructive procedures such as considering the tendons to be transferred.

An anomalous muscle mimicking a dorso-radial ganglion as a cause of radial wrist pain

We report an abnormal muscle on the radial aspect of the wrist, which presented clinically as a ganglion and radial wrist pain. Existence of muscles in the first compartment has been accounted earlier, however its atypical presentation advocates its inclusion in the differential diagnosis of a dorso-radial ganglion and wrist pain.

The extensor indicis et medii communis

The aim of this study was to examine the existence of the extensor indicis et medii communis in detail. Thirty-one randomly selected adult cadavers (62 upper extremities) were examined for this project (22 males and 9 females between the ages 38 and 87). The muscle was observed in 3 of 62 hands, an incidence of 4.8%. One was in the right and the other two were in the left hands. Mean length and width of the muscle belly were 4.5 +/- 0.8 and 0.8 +/- 0.3 mm, respectively. Although the muscle did not have a junctura tendinum attachment between its two tendons, in one hand, the tendon to the index finger gave a thin slip to the tendon of the extensor digitorum communis for the same finger. Knowledge of variant muscle may be important when one is assessing the traumatized or diseased hand.

Extensor carpi ulnaris problems at the wrist--classification, surgical treatment and results

Twenty-eight extensor carpi ulnaris lesions at the wrist were treated surgically between 1990 and 2002. Fifteen patients had an isolated extensor carpi ulnaris tenosynovitis or tendinopathy, five had extensor carpi ulnaris dislocation, four had an extensor carpi ulnaris subluxation and four had an extensor carpi ulnaris rupture. Seventeen patients first developed their symptoms while playing sports. At a mean follow-up of 23 months, twenty-two patients had returned to their previous activities. Seven of the 27 patients had lost more than 30% of their grip strength and five had restricted wrist motion. Two needed an extensor carpi ulnaris tenolysis. Pure isolated extensor carpi ulnaris lesions are rare and associated ulnar sided lesions (eleven triangular fibrocartilage complex tears and four lunotriquetral ligament tears), as well as possible predisposing factors (seven anomalous tendon slips, four ulnar styloid non-unions and one flat extensor carpi ulnaris tendon groove), were frequent. A classification of extensor carpi ulnaris tendon and subsheath lesions was developed to allow the surgeon to adequately evaluate the different components of these lesions.

Ganglion cysts and other tumor related conditions of the hand and wrist

Most regard ganglion, giant cell tumor of tendon sheath and epidermal inclusion cysts as tumor-like conditions as opposed to true neoplasms. Ganglion cysts are the most common lesion of the hand and wrist, accounting for 50% to 70% of all masses identified. The majority of ganglion cysts can be treated nonoperatively but when surgery is performed a low recurrence rate can be anticipated. Giant cell tumor of the tendon sheath hand epidermoid cysts are also common hand lesions that require surgical excision in most instances. Of the three, giant cell tumor of tendon sheath have the most notable recurrence rates. This article reviews the clinical presentations of these lesions as well as their proposed pathophysiology.

Imaging of wrist masses

The wrist is a complex structure with an extensive differential diagnosis for a presenting mass. However, the vast majority of hand and wrist masses are benign, and many of these have a distinctive radiographic appearance. In this article, the imaging characteristics of the most common entities are reviewed with particular attention to magnetic resonance appearance. The 3 most common hand and wrist lesions include ganglion cysts, giant cell tumors of the tendon sheath, and hemangiomas. Other common lesions that can be diagnosed radiographically include lipomas, neural sheath tumors, infection and inflammation, and variant soft-tissue or bony structures. The appearance of the fibrolipomatous hamartoma will also be demonstrated because this is a radiographically distinctive, though rare, lesion.

Musculotendinous Anomalies in Musician and Nonmusician Hands

Musculoskeletal abnormalities of musicians' hands and upper extremities are well-recognized and potentially career-threatening problems. Of the many types of potentiality problematic musculoskeletal disorders that could be assessed, this study focused on joint instability and musculotendinous anomalies. For this study, the hands of 92 music students were compared with the hands of 64 nonmusician control subjects. Flexor anomalies were observed much more frequently than extensor musculotendinous anomalies; clinical evidence of the Linburg-Comstock anomaly was noted for 60 to 70 percent of subjects in both groups. Further analysis of the Linburg-Comstock anomaly demonstrated that the sites of pain among test-positive subjects were variable, test positivity was more frequent in the left hand and among string players, and test positivity tended to decrease from the radial side to the ulnar side of the hand. There were only two definite extensor musculotendinous anomalies (1.3 percent), and both involved a subluxating extensor mechanism affecting the little fingers. Forty-three percent of all subjects exhibited a degree of instability affecting the joints of their hands.

Supernumerary extensor pollicis longus tendon: a case report

We report a rare case in which the extensor pollicis longus (EPL) tendon was separated into 2 slips at the site of origin, ran an abnormal course across the wrist, and combined in the vicinity of the metacarpophalangeal (MCP) joint; the tendon on the radial side passed through another tendon sheath between the first and second compartments and the tendon on the ulnar side passed over the extensor retinaculum.

Extensor digitorum brevis manus: A case of fourth-compartment syndrome

The presence of an extensor digitorum brevis manus represents a variation of the normal anatomy of the fourth extensor compartment of the wrist. It usually presents as a swelling on the dorsum of the wrist and is often inaccurately diagnosed. An awareness of its existence and of its characteristic appearance on diagnostic imaging studies is the basis for diagnosis. Symptomatic cases require division of the extensor retinaculum or excision of the muscle, depending on subtype, while asymptomatic cases require no intervention.

Extensor digitorum brevis manus muscle in a patient with neurofibromatosis type 1

The extensor digitorum brevis manus is an uncommon muscle on the dorsum of the hand and can be misdiagnosed, particularly when associated with other clinical conditions such as neurofibromatosis type 1. To our knowledge the two clinical pictures have never been described together. The aim of our report is to increase the clinician's familiarity with these combined conditions, to investigate the available diagnostic tools, and to achieve a correct diagnosis.

Extensor digitorum brevis manus: anatomical, radiological and clinical relevance. A review

The extensor digitorum brevis manus (EDBM) is a supernumerary muscle in the dorsum of the hand frequently misdiagnosed as a dorsal wrist ganglion, exostosis, tendon sheath cyst or synovitis. Its presence in a living subject, confirmed by magnetic resonance imaging (MRI), is presented together with a review of the hitherto reported cases and the results of an anatomical study on 128 adult human cadavers (59 males and 69 females). The EDBM was found in three (2.3%) of the 128 cadavers. It occurred in two (3.4%) of the 59 male cadavers (one bilateral and one unilateral on the right side) and in one (1.5%) of the 69 female cadavers (unilateral on the left side). Consequently, the EDBM was found in four (1.6%) of the 256 upper limbs. It originated from the dorsal wrist capsule within the compartment deep to the extensor retinaculum for the extensor digitorum and inserted into the extensor hood of the index finger in one case and into that of the middle finger in three cases. In both hands of the living subject, the origin was similar but the insertion was into the index and middle fingers. In all cases, it was innervated by the posterior interosseous nerve and its blood supply was provided by the posterior interosseous artery.