The accessory tendon of extensor hallucis longus muscle and its correlation to hallux valgus deformity: a cadaveric study

Positional and dimensional relation of tendons around the first metatarsal bone with hallux valgus

PURPOSE

It was aimed to reveal whether the positions and dimensions of the extrinsic and intrinsic muscle tendons related to the hallux around the first metatarsal bone are affected by the severity of hallux valgus (HV) and whether tendon positional changes and tendon sizes affect each other.

METHODS

In formalin-fixed 46 feet, three HV angle subgroups (normal, mild, and moderate/severe) were defined. Width, thickness, and cross-sectional area (CSA) of tendons of the extensor hallucis longus (EHL) and brevis (EHB), abductor hallucis (AH), and flexor hallucis longus (FHL) were measured. On the clock model created in coronal plane, positional variations of each tendon were determined.

RESULTS

In the moderate/severe HV group, thickness and CSA of the EHB, width and CSA of the AH were smaller, compared to mild HV. Width and CSA of the FHL were smaller in moderate/severe HV than in the normal. Regardless of HV, the width and CSA of the FHL were greater in cases where the FHL was located more lateral, and the width of both FHL and AT were greater in cases where AH located was more plantar.

CONCLUSION

The smaller tendon size of two intrinsic (one plantar and one dorsal) and one extrinsic muscle in the moderate/severe HV group indicates that changes in the tendons are evident in cases of high severity of HV but not in cases of mild HV. Accordingly, the changes do not appear to be due to a factor limited to only one aspect of the foot. It is recommended to consider the possible biomechanical effects of AH, FHL, and EHB tendon dimensional weakness in surgical planning in moderate/severe HV cases.

Anatomical Characteristics of Extensor Hallucis Longus Tendon Variations and Its Clinical Implications: A Korean Cadaveric Study

The purpose of this study is to ascertain the morphological characteristics of the extensor hallucis longus (EHL) tendon variation using larger-scale dissection of Korean cadavers and to classify the types of variation along with incidence. A total of 158 feet from adult formalin-fixed cadavers (50 males, 29 females) were dissected. The morphological characteristics and measurements of the EHL tendon variants were evaluated. Three types of the EHL tendon variation were classified, wherein the most common type was Type 2 (106 feet, 67.1%), Type 3 (3 feet, 1.9%) was the rarest type, and Type 1 without accessory tendon was found in 49 feet (31.0%). Type 2K (11 feet, 7%) and Type 3K (1 foot, 0.6%) were described as new subtypes. The present study suggests morphological characteristics of the EHL tendon variation in Korean populations and high morphological variability of the EHL tendon along with the possibility of differences according to race or ethnicity and gender. Furthermore, a newly updated classification complemented by new subtypes of variation will help foot and ankle surgeons in diagnosis and surgical planning with hallux problems.

Coexistence of accessory band with the second type of extensor hallucis longus

The main muscles responsible for extension of the toes are the extensor digitorum longus and extensor hallucis longus. Morphological variants of both of these muscles are mostly related to the numbers of tendons and their unusual points of insertion. The case presented shows an accessory band deriving from the extensor digitorum longus and fusing with the extensor hallucis longus, a concomitant additional tendon of the latter inserting to the proximal phalanx of the hallux. Knowledge of these anatomical patterns is important not only from the anatomical but also the clinical point of view and can be useful in lower limb surgery.

Classifications of the extensor hallucis longus tendon variations: Updated and comprehensive narrative review

The extensor hallucis longus muscle originates from the anterior surface of the fibula and on the interosseous membrane medial to the origin of the extensor digitorum longus. Its distal attachment is typically located on the dorsal aspect of the distal phalanx of the hallux. However, EHL tendon variations have been reported in anatomical studies based on adults and fetuses. The most common variation is an additional tendinous slip in the region of the distal attachment. Additional tendinous slips can have specific names depending on where they insert. This wide range of morphological variations among the additional tendons has necessitated appropriate classification system to rank all types that could be used by clinicians. The main goal of this review is to summarize information from the available literature about the extensor hallucis longus muscle and to compare classification systems and the results of previous studies. Another aim is to create a new classification system.

Comparison of the insertion patterns of the extensor hallucis longus muscle in Korean focusing on the regional difference

PURPOSE

From the evolutionary myology, the additional tendon of the extensor hallucis longus (EHL) muscle represents the sample of a new acquisition. We aimed to determine whether the insertion pattern of the EHL muscle differs in Koreans according to demographic populations, especially between Jeju islanders and the Korean Peninsula inhabitants.

METHODS

We used 69 Korean cadavers and classified the tendinous insertion of the EHL muscle as Pattern I, Pattern II, and Pattern III. The ratio of each Pattern in adult cadaveric samples was compared between demographic populations.

RESULTS

The proportion of Pattern I, Pattern II, and Pattern III of the EHL muscle was 30.43, 63.77, and 5.80%, respectively, further divided into 18.00 vs. 36.04%, 72.00 vs. 60.47%, 10.00 vs. 3.49% in Jeju islanders vs. peninsular Koreans. There was a considerable difference in the insertion patterns of the EHL muscle in each regional group (p = 0.032), but not in each gender, age, and body sides of lower limbs.

CONCLUSION

The findings of this study indicate that there was a higher incidence of the accessory tendon(s) of the EHL muscle in Koreans and the distributed insertion patterns of the EHL muscle was significantly different between Jeju islanders and peninsular Koreans.

Anatomical Study of the Accessory Tendon of the Extensor Hallucis Longus Muscle and Its Clinical Application

Backgroud

The accessory tendon of the extensor hallucis longus (ATEHL) muscle is a common abnormal structure, and its clinical significance remains debatable. In this study, we provide the incidence of the ATEHL and characterize its morphological types in Asian cadavers and investigate its clinical applications.

Methods

The tendons from 50 adult cadaveric feet, fixed in 10% formalin, were analyzed. We measured the length and width of both the ATEHL and the extensor hallucis brevis (EHB).

Results

All dissected specimens had an ATEHL. The first metatarsophalangeal joint was surrounded by an accessory tendon that inserted onto the joint capsule and the dorsal base of the proximal phalanx. We classified the ATEHL into 3 types based on their directions. Differences in ATEHL type based on sex were not statistically significant.

Conclusions

We found an ATEHL in all cadaveric specimens in this study. We surmise that the ATEHL acts as an antagonist with the EHB when the toe is extending, which might help prevent the occurrence of hallux valgus deformity.

Characteristics of the accessory tendon of the extensor hallucis longus muscle: a Taiwanese study

PURPOSE

The main tendon of the extensor hallucis longus (EHL) muscle attaches to the dorsal aspect of the distal phalanx of the great toe. One or multiple accessory tendons of the EHL have been reported in several ethnic/regional groups, except Taiwan. This study aimed to investigate the incidence, length, and insertion of the accessory tendon of the EHL in Taiwanese people.

METHODS

Anatomical dissection was performed on 48 feet of 24 formalin-embalmed cadavers. The occurrence and morphological characteristics of the accessory tendon of the EHL were recorded and analyzed.

RESULTS

The accessory tendon of the EHL was found in 97.92% (47/48) of the legs that were dissected. In one male cadaver, an independent muscle belly was identified in each leg, whereas all the other accessory tendons originated from the main tendon of the EHL. In this study, the insertion of the accessory tendon were classified into four patterns. The most common insertion sites were the first metatarsophalangeal (MTP) joint capsule and proximal phalanx of the great toe. The length of the accessory tendons did not correlate with age or with sex when the two tendons with independent muscle belly were excluded.

CONCLUSIONS

The accessory tendon of the EHL appears to be a regular feature in Taiwanese people. Most accessory tendons of the EHL (85.7%) attached on the first MTP joint capsule may play a role in the prevention of capsular impingement during great toe extension.

Independent muscle of extensor hallucis capsularis: a cadaveric case report

Extensor hallucis capsularis (EHC) is an accessory tendon located medially to extensor halluces longus (EHL) tendon. Most EHC is known to originate as a tendinous slip of the EHL tendon, although it may be splitted from the tibialis anterior (TA) tendon or the extensor halluces brevis (EHB) tendon. During routine dissection of a 49-year-old male cadaver, independent muscle bellies of EHC were discovered bilaterally. The EHL muscle arose from the middle anteromedial aspect of fibula, lateral to the origin of TA muscle and medial to extensor digitorum longus (EDL) muscle. An additional muscle bellies were separated from EHL muscle at the point of 6 cm away from EHL origin in the right leg, and 3 cm away in the left. They coursed downward as EHC to reach the first metatarsophalangeal joint capsule. This muscle, unlike the variations identified to date, is considered to extend to EHC, and the name "extensor hallucis capsularis muscle" is offered. This kind of variation may be important for investigating the development of deformity at the first metatarsophalangeal joint, such as hallux valgus.

Comparison of the Intrinsic Foot Muscle Activities between Therapeutic and Three-Dimensional Foot-Ankle Exercises in Healthy Adults: An Explanatory Study

Background: In recent years, a three-dimensional ankle exercise has been proposed as a practice for strengthening the intrinsic foot muscles, however this topic still requires further research. This study aimed to compare the activities of the intrinsic muscles in healthy participants during 3D foot–ankle exercises, namely, short foot (SF), and toe spread out (TSO). Methods: Prior to the experiment, 16 healthy adults were trained on how to perform SF, TSO, and 3D foot–ankle exercises for an hour. Once all participants passed the foot–ankle exercise performance test, we randomly measured the activity of the intrinsic foot muscles using electromyography while the patients were performing foot–ankle exercises. Results: The abductor hallucis (AbH), extensor hallucis longus (EHL), and flexor hallucis brevis (FHB) activities showed significant differences among the exercises for intrinsic foot muscle strengthening (p < 0.01). Additionally, the AbH/AdH (adductor hallucis) ratio showed significant differences among the exercises for strengthening the intrinsic foot muscles (p < 0.01). Conclusions: Our results showed that the 3D extension exercise is as effective as the therapeutic exercise in terms of the AbH and FHB activities, and the AbH/AdH ratio. On the contrary, the 3D flexion exercise showed superiority in terms of the EHL activity.

HALLUX VALGUS ANATOMICAL ALTERATIONS AND ITS CORRELATION WITH THE RADIOGRAPHIC FINDINGS

Objective:

To describe the anatomical and pathological osteoarticular, muscular and tendinous variations in feet of cadavers with hallux valgus and to correlate them with the degree of radiographic deformity.

Methods:

Dissections and radiographs were conducted in the feet of 22 cadavers with halux valgus, aged between 20 and 70 years. The feet affected were compared with 5 normal feet in order to document the anatomical and pathological, myotendinous and articular variations found.

Results:

The extensor hallucis longus and brevis tendons were arched in all degrees of deformity, causing a lateral deviation that forms the arc chord of the metatarsophalangeal angle of the hallux. We also observed a deviation to the plantar face of the abductor muscle tendon and lateral deviation of the flexor hallucis muscle tendon. In the moderate deformities, the medial deviation of the first metatarsal head was observed, sliding out of the sesamoid apparatus, pronation of this head, and formation of medial exostoses. In severe deformities, in addition to all other deformities, we found the extensor hallucis longus tendon with two distal insertions, rather than just one.

Conclusion:

The anatomical alterations found in the hallux valgus may be related to the degree of radiographic deformity. Level of Evidence IV, Case series.

Double origin of the extensor hallucis longus muscle: a case report

Most of the anatomic variations of the extensor hallucis longus (EHL) muscle are related to the tendon of insertion. We show a double origin of the EHL from the medial aspect of the fibula and the lateral aspect of the tibia. A 27-year-old male with a double closed fracture of tibia and fibula showed an involuntary extension of the big toe during foot plantar flexion after surgery. A tendon fibrosis by the fixation plates could be the cause of the foot functional alteration. Interestingly, the anatomic variation described could be related to the postsurgical foot dysfunction, since when the fibrotic tissue was removed the normal extension of big toe recovered. As illustrated in this case report, knowledge of anatomic variations is very useful, particularly in the context of foot surgery.

A cadaveric study of the morphology of the extensor hallucis longus - a proposal for a new classification

Background

Morphological variations of the EHL concern mainly the accessory tendons and the site of their insertion. The aim of our study is to present a new classification of the EHL.

Methods

Classical anatomical dissection was performed on 104 lower limbs (51 right, 53 left, fixed in 10% formalin solution).

Results

In the cadavers, three types of morphology (insertion and addidtional band) were observed. Type I, the most common type, was characterized by a single tendon that ends as an extensor hood on the dorsal aspect of the base of the distal phalanx of the big toe (57.7%). Type II was characterized by two distal tendons and was subdivided into three subtypes according to (A-29.9%, B-4.8% and C-5.7%). Type III was characterised by three distal tendons (two cases - 1.9%).

Conclusion

The EHL presents high morphological variability. Knowledge of particular types of insertion is essential for both clinicians and anatomists.

Electronic supplementary material

The online version of this article (10.1186/s12891-019-2688-8) contains supplementary material, which is available to authorized users.