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

Outcomes of Platelet-Rich Plasma Infiltration and Weightbearing Cast Immobilization in Distal Tibialis Anterior Tendinopathy: A Prospective Cohort Study

BACKGROUND

Distal tibialis anterior tendinopathy (DTAT) is a chronic condition that may lead to functional impairment and secondary forefoot deformities when left untreated. Current clinical practice is mainly guided by case reports and small retrospective case series; little consensus exists on which treatment protocol is most effective. This study aims to assess a conservative treatment for DTAT consisting of PRP infiltration and walking cast immobilization.

METHODS

This prospective study included 18 feet in 18 patients, recruited between September 2020 and September 2022 at a single institution. Ultrasonography was performed; leukocyte-poor PRP was infiltrated around the tibialis anterior tendon insertion. Walking cast immobilization was used for 3 weeks after infiltration, followed by eccentric exercises of the DTAT, and gastrocnemius-soleus muscle complex stretching. Clinical findings, visual analog scale (VAS), Foot Function Index (FFI), and American Orthopaedic Foot & Ankle Society (AOFAS) midfoot scores were recorded at inclusion, and 6 and 12 weeks after PRP infiltration. Minimal clinically important difference (MCID) limits were researched to assess clinical relevance of statistical outcomes. Means were determined for age, sex, and body mass index (BMI). One-way repeated measures ANOVA was performed over time for FFI, AOFAS, and VAS scores.

RESULTS

Mean age was 65 years with a mean BMI of 25. Tendon thickening and hypoechogenicity were the most commonly reported ultrasonographic findings. Significant improvement from baseline VAS (VASrest: 4.71 ± 2.7, VASactivity: 5.66 ± 2.5) to 12 weeks follow-up (VASrest: 2.14 ± 2.7, VASactivity: 3.34 ± 2.5) was found. Both AOFAS and FFITotal improved significantly from baseline (AOFAS: 66.9 ± 3.3, FFITotal: 32.9 ± 3.3) to 6-week follow-up (AOFAS6w: 79.4 ± 3.3, P = .019; FFITotal: 19.4 ± 3.3, P = .011). No statistically significant further improvement was found at 12 weeks compared to 6 weeks' follow-up. Two (11%) patients chose operative treatment because of persisting symptoms.

CONCLUSION

We found that PRP infiltration with walking cast immobilization as a first-line treatment was associated with general early symptom improvement.

LEVEL OF EVIDENCE

Level IV, case series.

Concomitant variations of the tibialis anterior, and extensor hallucis longus, and extensor hallucis brevis muscles

Tibialis anterior (TA) muscle originates from the lateral surface of tibia and its tendon attaches to the medial cuneiform and base of the first metatarsal. The TA muscle is responsible for both dorsiflexion and inversion of the foot. We present a case of bilateral TA muscle variations that diverge slightly from the current classification systems of this muscle. Recognizing variations such as these may be important for anatomists, surgeons, podiatrists, and physicians. Following routine dissection, an accessory tendon of the TA muscle was found on both sides. Accessory tendons of the extensor hallucis longus and extensor hallucis brevis joined to form a common tendon on both sides. We believe that this unique case will help further the classification systems for the tendons of the TA and also be informative for clinical anatomists as well as physicians treating patients with pathology in this region.

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.

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.