Flexor Digitorum Accessorius Longus Muscle Research Articles

A Rare Case of Flexor Digitorum Accessorius Longus Muscle Presenting as Tarsal Tunnel Syndrome.

Tarsal tunnel syndrome (TTS) is a relatively uncommon nerve entrapment neuropathy. Many pathologies are reported as possible causes for TTS. The diagnosis of TTS can be difficult and often missed. We present a rare case of TTS due to an accessory flexor digitorum longus muscle. Together with a high index of suspicion, MRI is the investigation of choice in making the diagnosis. These patients are best managed with excision or transposition of the flexor digitorum accessorius longus (FDAL) and neurolysis of the posterior tibial nerve and its branches.

Unusual bilateral variation of the flexor digitorum accessorius longus muscle and its relation on tarsal tunnel syndrome.

During standard anatomical dissection for a medical anatomy course, we encountered an unusual bilateral variant of a unipennate flexor digitorum accessorius longus (FDAL) muscle, a supernumery muscle of the deep posterior leg and medial ankle. We documented the muscles course and measured the diameter and length of the FDAL muscle belly, as well as the full length of its tendinous attachments. On both right and left legs, the FDAL originated from the proximal posterior fibula and distal one-third of the flexor hallucis longus muscle. The tendon had a distal attachment on the flexor digitorum longus (FDL) tendon and traveled with the FDL tendon as it inserted on the third distal phalanx. The left FDAL full length was 42.54cm; the length of the muscle belly was 16.26cm; and the circumference of the muscle belly was 4.44cm. The right FDAL full length was 44.20cm; the length of muscle belly was 12.06; and the circumference (belly) was 4.44cm. Surrounding musculature and neurovasculature follow standard anatomical courses. This anatomical documentation provides opportunities for clinicians to consider mechanical influences of the FDAL on plantar foot function and further consider the accessory ankle muscles that have the potential to cause compressive neuropathies such as tarsal tunnel syndrome.

Accessory posterior leg muscles encountered during surgery for achilles tendon pathology: A case series

Accessory muscles in the posterior leg compartment are commonly encountered. Although accessory muscles are usually asymptomatic, they can lead to symptomatology. Accessory muscles were found in three patients who underwent surgery for symptomatic Achilles tendon pathology . Two patients had a flexor digitorum accessorius longus muscle and one had an accessory soleus muscle. Magnetic resonance imaging is a useful resource to assess tendinopathies. If an accessory muscle is present and identified on mangnetic resonance imaging, the surgeon can tailor their surgical plan accordingly.

Incision of the flexor retinaculum of the foot fails to relieve symptoms of tarsal tunnel syndrome due to presence of a variant flexor digitorum accessorius longus (FDAL) muscle

Tarsal tunnel syndrome (TTS), or posterior tibial neuralgia, is a neuropathy associated with compressive entrapment of the tibial nerve as it travels deep to the flexor retinaculum of the foot, or within the tarsal tunnel. A patient with TTS often presents with paresthesia and numbness within the foot radiating to the big toe and first three toes, but these symptoms can also radiate proximally into the leg as far as the knee joint. Pain, burning, tingling, and electrical sensations extend over the plantar surface of the foot and the heel. Inflammation and swelling can result leading to compression of the tibial nerve. These symptoms are exacerbated with activity or when a physician applies pressure to, or taps upon, the compressed tibial nerve, which is called a positive Tinel's sign. Surgical incision the flexor retinaculum of the foot usually relieves these TTS signs/symptoms because it creates additional space for the impinged tibial nerve in this compressive entrapment neuropathy.A 44‐year‐old competitive male athlete, who was diagnosed with TTS, failed to gain relief from the signs and symptoms of this neuropathy after incision of the flexor retinaculum of the foot. Subsequent MRI review revealed a large variant muscle in the posterior compartment of the distal affected leg, which was later identified as a flexor digitorum accessorius longus (FDAL). This variant muscle arose from the investing fascia of the flexor digitorum longus muscle medially, the transverse intermuscular septum posteriorly, the investing fascia of the flexor hallucis longus muscle medially. This FDAL also extended as far proximally as the middle of leg, and more specifically, the lower border of the gastrocnemius muscle. Though difficult to discern on the MRI, the FDAL appeared to attach to the tibia medially and fibula laterally. Throughout its course, the FDAL muscle was located immediately posterior and impinged upon the tibial nerve. Moreover, this FDAL followed its documented course distally in that it was located posterior to the medial malleolus and entered the tarsal tunnel (deep to the flexor retinaculum), where it continued to act as a space occupying lesion. Finally, the FDAL inserted onto the intersection of the flexor digitorum longus tendon and the quadratus plantae muscle in the second muscular layer of the sole of the foot.To regain the quality of his once active lifestyle, it was necessary for this patient to undergo an addition surgery, using an open approach, in which this FDAL muscle was excised from its proximal attachment to just below the normal location of the flexor retinaculum of the foot. With the prevalence of the FDAL reported in 2–12% of cadaveric studies, this case emphasizes the importance of MRI review before tarsal tunnel surgery is performed and the importance of identifying variant leg muscles that may be causing the compressive entrapment neuropathy of the tibial nerve.Support or Funding InformationWVU Initiation to Research Opportunities (INTRO) Program; NASA WV Space Grant Consortium [NNX10AK62H].This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Anatomical characteristics of the flexor digitorum accessorius longus muscle and their relevance to tarsal tunnel syndrome a systematic review.

Clinical and cadaver studies have reported that supernumerary muscles could be the etiology of a variety of pathologic disorders, such as posterior impingement syndrome, tarsal tunnel syndrome (TTS), and flexor hallucis longus tenosynovitis. We describe a unique variant of the flexor digitorum accessorius longus (FDAL) muscle as an apparent cause of TTS, functioning as an independent flexor of the second toe, which has not been described in the literature. In addition to this case report, a systematic review was performed of TTS caused by the FDAL muscle. A targeted search of PubMed, the Cochrane Library, the Cumulative Index to Nursing and Allied Health Literature, and Web of Science identified full-text papers that fulfilled the inclusion and exclusion criteria. Twenty-nine papers were identified for inclusion in the systematic review: 12 clinical papers of TTS caused by the FDAL muscle and 17 cadaver-based papers. Clinicians often do not include the FDAL muscle in the differential diagnosis of TTS. This literature review suggests that the FDAL is an important muscle in terms of its functional and clinical significance. Knowledge of this muscle, its anatomical location and variations, and its magnetic resonance imaging characteristics may help clinicians make an accurate differential diagnosis.

Morphological Description of the Flexor Digitorum Accessorius Longus Muscle and its Clinical Significance

OTTONE, N. E.; TEJEDOR, M; BLASI, E.; MEDAN, C. D.; FUENTES, R. & DEL SOL, M. Morphological description of theflexor digitorum accessorius longus muscle and its clinical significance. Int. J. Morphol., 33(2):611-619, 2015.SUMMARY: The flexor digitorum accessorius longus muscle (FDALM) is an anatomical variation that occurs with low frequencyin the leg and feet. It was first described by Meckel in 1818. It arises from the tibia or fibula and extends from this towards the quadratusplantae muscle or the flexor digitorum longus muscle, crossing the medial retromalleolar canal and creating a close relationshi p with theelements of the tibialis posterior neurovascular bundle. A hundred and ten legs were dissected from Caucasian, adult, undefined sexcadavers, previously kept in 5% formalin solution. We developed a dissection technique in 2 times to search for and find the flexordigitorum accessorius longus muscle, essential for the safe and successful development of surgical procedures in the region. Th ree casesof flexor digitorum accessorius longus muscle muscle were described. Two of them were founded in the same cadaver, in a bilateraldisposition. Knowledge of this muscle variation, its embryonic origin and the possibility of finding during clinical studies an d invasiveprocedures in the leg and feet is important for differential diagnosis in compressive pathologies.KEY WORDS: Flexor digitorum accessorius longus muscle; Compressive pathologies; Anatomical variation

Flexor digitorum accessorius longus muscle in resistant clubfoot patients: introduction of a new sign predicting its presence.

Clubfoot, talipes equino varus (TEV), is a common congenital foot anomaly. Some cases are resistant to conservative treatment. Many causes of resistance have been reported, among these, the presence of anomalous muscles; however, the effect of the presence of anomalous muscles on the outcome of conservative management is not well studied. These aberrant muscles are discovered during the extensive surgical release as an abnormal finding. The aim of this work is to study the demographic characteristics of patients with resistant TEV that necessitated extensive soft tissue release at Sudan Clubfoot Clinic and to document the prevalence of flexor digitorum accessorius longus (FDAL) muscle in a large series of clubfoot patients treated by extensive surgery: posteromedial release. Also, we introduce a new observation as an indication by which the surgeon can predict the presence of FDAL. On the basis of an observation that there is a special posture of the big toe in extension in relation to other flexed toes associated with the presence of FDAL, records of patients of clubfoot treated by extensive surgery between 2007 and 2012 at the Sudan Clubfoot Project were reviewed. Demographic characteristics were studied. Only patients with idiopathic TEV were included. Resistant clubfeet necessitated extensive release in 261 patients, 197 males and 64 females. Their ages ranged between 1 day and 15 years at presentation. FDAL muscle was found in 48 patients (54 feet) out of 261 patients (411 feet, 13.14%). In 46 of the 48 patients (95.8%), the presence of the FDAL could be predicted by a sign. FDAL is prevalent in 13% of resistant TEV cases requiring extensive soft tissue release, and the surgeon can expect resistant clubfoot and predict the presence of the FDAL in over 95% before he operates by observing the Samir-Adam sign.

Classification system for flexor digitorum accessorius longus muscle variants within the leg: Clinical correlations

The flexor digitorum accessorius longus (FDAL), a variant leg muscle, can cause tarsal tunnel syndrome. This study was performed to classify the variants of the FDAL by dissection and to correlate the dissection results with clinical cases of tarsal tunnel syndrome caused by this muscle. Eighty lower limbs of embalmed Korean cadavers were dissected. MR images of two clinical cases of tarsal tunnel syndrome caused by the FDAL were correlated with the dissection results. The FDAL was observed in nine out of 80 specimens (11.3%) and it was classified into three types depending on its site of origin and its relationship to the posterior tibial neurovascular bundle (PTNV) in the leg. In Type I (6.3%), the FDAL originated in the leg and ran superficially along the PTNV, either not crossing (Type Ia, 3.8%) or crossing (Type Ib, 2.5%) the neurovascular bundle. In Type II (6.3%), it originated in the tarsal tunnel. Most FDALs followed a similar course in the tarsal tunnel and the plantar pedis. On correlating the MR images of the clinical cases with this classification, the FDAL corresponded to Types Ia and II. All three types of FDAL can compress the tibial nerve in the tarsal tunnel or the distal leg. Clarification of the topographical relationship between this muscle and the PTNV would help to improve the results of surgery for tarsal tunnel syndrome caused by the FDAL.

An Unusual Aberrant Muscle in Congenital Clubfoot: An Intraoperative Finding

Congenital clubfoot is a common congenital deformity, characterized by equinus of the hindfoot and adduction of the midfoot and forefoot, with varus through the subtalar joint complex. A cavus deformity will also be present. The etiology of this congenital deformity remains elusive. Muscle anomalies are not commonly found in patients with idiopathic clubfoot, and, when present, their significance is not clear. The presence of a flexor digitorum accessorius longus muscle and an accessory soleus muscle found at surgical correction of clubfoot deformity has been previously reported. Our case was a female child, aged 2 years, 3 months, who developed bilateral relapsed congenital clubfoot. She was found to have an unusual aberrant muscle in both legs. This was discovered accidentally during surgical correction of her deformity through posteromedial soft tissue release. This muscle might have contributed to the hindfoot varus and equinus in the clubfoot deformity, because the latter were completely corrected after release of the muscle from its insertion. Awareness of such a new anatomic variant, with the other anatomic variants found in clubfoot deformity, will not only improve our understanding of normal lower limb development, but could also lead to improved genetic counseling and diagnostic and treatment methods of such a common congenital deformity.

Tarsal tunnel syndrome caused by a flexor digitorum accessorius longus muscle: a case report and review of the literature

The flexor digitorum accessorius longus (FDAL) is a rare muscular occurrence in the lower extremity. In this case study and review of the literature the cause of tarsal tunnel syndrome by a flexor digitorum accessorius longus is described with emphasis on clinical testing methods, diagnostic imaging and both non-surgical and surgical management. A 52 year old male presented with pain and paraesthesia in his left foot and ankle. Tinel’s sign was exhibited clinically as well as severe bilateral pes planus. Inverted style custom foot orthoses failed to reduce the patient’ ss ymptoms over as ix month period. Magnetic resonance imaging (MRI) confirmed the presence of a FDAL muscle within the tarsal tunnel. The patient was subsequently referred to a podiatric surgeon for decompression and excision of the accessory muscle. Follow up at 18 months revealed resolution of pain and return to normal activities however, some plantar paraesthesia remained. A literature search was conducted across several major scientific databases. Further information was sought with citation tracking, reference checking, reviewing unpublished data and seeking expert opinion. The search yielded sixteen research papers pertaining to the FDAL muscle. Six of these papers described the FDAL as the cause of TTS in the form of case studies and were included in the review. Pain and paraesthesia were described as the pertinent symptoms and indicative of neural pathology, as was a Tinel’s sign. MRI was preferred for diagnostic purposes due to the ability to detect space-occupying lesions within the tarsal tunnel. In some cases FDAL was diagnosed intra-operatively. Surgical decompression via excision of the accessory muscle was described with a reportedly high success rate. Practitioners treating the foot and ankle should have a degree of suspicion for the presence of an accessory muscle particularly when interpreting MRI films as part of the diagnostic work-up for TTS.

Hindfoot endoscopy for accessory flexor digitorum longus and flexor hallucis longus tenosynovitis

We present a case report involving the flexor digitorum accessorius longus (FDAL) tendon which travels through a fibro-osseous tunnel together with the flexor hallucis longus (FHL) tendon, causing a stenosing tenosynovitis. The patient was admitted with posteromedial ankle pain and diagnosed clinically as FHL tenosynovitis. We found two tendons in the tunnel during hindfoot endoscopy. The stenosis was relieved by endoscopic debridement. After the operation, we checked the MRI images and observed two tendons. We concluded that the accessory tendon was the FDAL. Two years later the patient was admitted with the same symptoms. We excised the FDAL muscle and the patient's symptoms resolved. The FDAL muscle is a cause of FHL tenosynovitis. Because of its variability and mostly asymptomatic nature, it may not be noticed it on an MRI scan. Hindfoot endoscopy is a safe tool for the diagnosis of this condition and curative treatment is afforded by excision of the FDAL muscle.

Identification of a flexor digitorum accessorius longus muscle with unique distal attachments

During a cadaver dissection in a gross anatomy course, a flexor digitorum accessorius longus (FDAL) muscle was identified. The FDAL was a unilateral, two-headed, multipennate muscle originating from the flexor retinaculum, deep fascia, and calcaneus. The muscle bodies fused into one tendon and coursed distally where slips were observed inserting into the flexor digitorum longus tendon and the flexor hallicus longus tendon. A survey of the literature revealed that an FDAL may be present in approximately 15% of the general population. Our results concerning the FDAL suggest the need for clinicians to recognize the occurrence and variability of accessory leg and ankle muscles, and to use available technology such as MRI to assist with the diagnosis and treatment of compressive neuropathies of the foot.

An unusual variation of the flexor digitorum accessorius longus muscle—its anatomy and clinical significance

In this article we describe a variant accessory muscle found in the deep posterior compartment of the leg in a 96 year-old female human cadaver. The flexor digitorum accessorius longus was found bilaterally, originating by two heads from the shafts of the tibia and fibula. The two heads of the muscle were observed to be subequal in size and none of the fleshy fibers of the muscle entered the tarsal tunnel. This stands in contrast with previous descriptions of accessory digital flexors, which are typically asymmetrical or single-headed, and which almost always introduce fleshy fibers into the tarsal tunnel. This variant structure has the potential to entrap the tibial nerve and compress the posterior tibial vessels either proximal to the talocrural joint or within the tarsal tunnel, and may be implicated in clinical scenarios involving imaging, surgery, compartment syndromes, or deep-vein thromboses.

Flexor Digitorum Accessorius Longus Muscle Is Associated With Familial Idiopathic Clubfoot

The etiology of idiopathic and familial clubfoot remains elusive. The purpose of this study was to document the prevalence of the flexor digitorum accessorius longus muscle in a large series of children treated with an extensive soft tissue release for idiopathic clubfoot deformity and compare those patients with and without this anomalous muscle in terms of various demographic data, including a positive family history of clubfoot. A retrospective review was conducted to identify infants treated with an extensive soft tissue release for idiopathic clubfoot deformity at the authors' institutions between 1980 and 2000. Patient characteristics and family demographic data were analyzed using multiple logistic regression analysis modeling the probability of having the anomalous flexor muscle. A flexor digitorum accessorius longus muscle was identified in 55 (6.6%) of the 835 patients at the time of surgical correction of the clubfoot deformity. It was present in 4.5% of patients without a family history (33/741) and 23.4% of patients with a family history (22/94) (P < 0.0001). Children with first-degree relatives with clubfoot are 6.6 times more likely to have the anomalous flexor muscle than children without first-degree relatives with clubfoot (odds ratio 6.6; 95% confidence interval 3.63-11.84; P < 0.0001).

Recognition of the flexor digitorum accessorius longus.

The flexor digitorum accessorius longus muscle was observed during a cadaveric surgery course on the foot and ankle for third-year podiatric medical students. The cadaveric foot had been amputated just proximal to the ankle level so that the muscle origin could not be determined; its insertion, however, was found to be into the flexor digitorum longus tendon, just before the tendon split into its digital slips. This article reviews the literature on the muscle and its clinical implications and describes and shows the muscle as it was seen in this case.

Flexor digitorum accessorius longus muscle: An etiology of tarsal tunnel syndrome?

During routine lower extremity laboratory dissection at the Ohio College of Podiatric Medicine, an anomalous muscle, the flexor digitorum accessorius longus was uncovered on one male and one female cadaver. The muscles were located in the deep posterior compartment of the leg and were of differing sizes and origins. This anomalous muscle has been implicated as an etiology for tarsal tunnel syndrome. In cases of tarsal tunnel syndrome that undergo surgical decompression, the flexor digitorum accessorius longus muscle may be present and may be the cause of the tibial nerve compression.

Flexor digitorum accessorius longus muscle.

The flexor digitorum accessorius longus muscle was encountered during routine dissection of the posteromedial region of the left ankle of an 84-year-old female cadaver, by a first year podiatric medical student, in a lower extremity anatomy laboratory session. The purpose of this article is to describe the flexor digitorum accessorius longus muscle as it appeared in the cadaver; to provide background information on the muscle; and provide clinical implications for the podiatric medical practitioner.