Accessory soleus muscle. A report of 4 cases and review of literature

A New Test for Achilles Tendinopathy Based on Kager's Fat Pad Clinical Assessment Predictive Values

Background This study aimed to check the diagnostic accuracy of a new test to identify Achilles tendinopathy.

STUDY DESIGN

Observational study.

METHODS

Seventy patients recruited from a private medical centre met the diagnostic criteria for unilateral Achilles tendinopathy (age, 45.1 ± 12.7 years; weight, 75.00 ± 10 kg; height, 1.75 ± 0.1 m) and were tested based on both Achilles tendons. Seventy patients with a unilateral Achilles tendinopathy ultrasound diagnosis were tested using David's test.

RESULTS

Most (86%) subjects demonstrated Kager's fat pad asymmetry in relation to the Achilles tendon in the complete passive dorsiflexion in the prone position (David's sign). No healthy tendons had David's sign.

CONCLUSIONS

The presence of asymmetry in Kager's fat pad in relation to the Achilles tendon during complete passive dorsiflexion is strongly indicative of ultrasound-diagnosed tendinopathy. David's test demonstrated a sensitivity of 85.71% (95% CI, 77.51% to 93.91%) and a specificity of 100% (95% CI, 100% to 100%), while noting the lack of blinding of the assessors and the uncertainty of the diagnostic measures (95% CI). Asymmetry of the fat pad could potentially serve as a characteristic marker for patients with Achilles tendinopathy.

Symptomatic accessory soleus muscle: A cause for exertional compartment syndrome in a young soldier: A case report

BACKGROUND

Accessory soleus muscle (ASM) is a rare congenital variation that is almost asymptomatic, but several papers have recently described symptomatic ASM. The clinical features of this condition are similar to tarsal tunnel syndrome (TTS) and include pain and numbness around the medial side of the ankle. ASM commonly originates from the fibula or soleus muscle and inserts into the Achilles tendon or calcaneus. Usually, it is identified as posteromedial swelling and definitely diagnosed by magnetic resonance imaging. In most cases, treatment is observation, but surgical excision can be considered if symptoms are severe.

CASE SUMMARY

A 23-year-old male Korean soldier presented with complaints of bilateral foot and ankle pain and a swelling medial to the Achilles tendon that was more pronounced on the right side. Symptoms first occurred after playing soccer 10 mo before this presentation, worsened after physical exertion, and were relieved by rest. He had no medical history, and no one in his family had the condition. Laboratory results were non-specific. Several tests were performed to exclude common diseases such as tumors or TTS. However, MRI revealed a bulky accessory soleus muscle in both feet, though the patient complained of more severe pain on the right side during physical activity. Accordingly, surgical resection was adopted. At surgery, a large accessory soleus muscle was noted anterior to the Achilles tendon with distinctive insertion from a normal soleus muscle. At 12 mo after surgery, there was no pain, numbness, or swelling of the right foot or ankle, no evidence of recurrence, and the patient could do all sports activities.

CONCLUSION

Accessory soleus muscle should be added to the list of differential diagnosis if a patient has pain, sole numbness or swelling of the posteromedial ankle.

Accessory Soleus Muscle: Two Case Reports with a Completely Different Presentation Caused by the Same Entity

Accessory soleus muscle (ASM) is a rare supernumerary anatomical variant that commonly presents as a posteromedial ankle swelling, which may become painful during physical activity. As it may mimic a soft tissue tumor, it is essential to differentiate this condition from ganglion, lipoma, hemangioma, synovioma, and sarcoma. However, ASM may also present with a painful syndrome, characterized by pain and paresthesia of the ankle and foot, mimicking the tarsal tunnel syndrome (TTS). Two cases of ASM are presented in this article. The first case had a typical presentation with painful posteromedial ankle swelling. After the initial assessment, the diagnosis was confirmed by magnetic resonance imaging (MRI), and ASM was treated by complete resection. The second case presented with pain and paresthesia in the right ankle and foot, but no swelling was noticeable. It was initially misdiagnosed by a rheumatologist and afterward overlooked on an MRI by a musculoskeletal radiology specialist and therefore mistreated by numerous physicians before being referred to our outpatient clinic. After further assessment, the diagnosis has been confirmed, and ASM was treated by complete resection combined with tarsal tunnel decompression. To the best of our knowledge, this is the first case reported in which ASM caused symptoms but presented without posteromedial swelling. This might be due to a proximally positioned belly of the ASM, followed by a tendinous insertion on the medial side of the calcaneus.

Ultrasound and Magnetic Resonance Imaging Diagnosis of Isolated Tear of the Accessory Soleus Tendon: A Case Report and Review of the Literatures

Introduction:

The accessory soleus muscle (also known as the supernumerary soleus or soleus secundus) is an uncommon congenital anatomical. The presence of this muscle is generally asymptomatic. In cases of symptomatic accessory soleus muscle, it manifests with painful swelling of the posteromedial region of the ankle. To the best of our knowledge, partial or complete accessory soleus tendon tears were reported in literature in only three cases; all of them were diagnosed with magnetic resonance imaging (MRI) examination while only one was diagnosed with both ultrasound (US) and MRI.

Case Report:

We presented a case of a 63-year-old Caucasian woman presented to our emergency department with severe pain in the posteromedial region of her right ankle. US and MRI of the calf and ankle were performed and a complete tear of the right accessory soleus tendon with fluid gap and myotendinous retraction was diagnosed.

Conclusion:

An accessory soleus muscle partial or complete tears are very uncommon injuries. This condition can mimic many other pathologies, and therefore, radiologists should know the physiological and pathological imaging findings for a correct interpretation of ankle injuries, avoiding misinterpretations.

Extrinsic compression neuropathy of the tibial nerve secondary to accessory soleus muscle in a young teenager

Compression neuropathy of the tibial nerve or one of its terminal branches (tarsal tunnel syndrome) is relatively uncommon. Accessory musculature on the posteromedial aspect of the ankle is a rare extrinsic cause of compression. Therefore, it should be considered in patients with prolonged manifestations of tibial nerve compression. A detailed history and physical examination, together with proper radiological evaluation, allow for accurate diagnosis. In this case report, a 13-year old female teenager on history, physical examination, and imaging studies was diagnosed as compression neuropathy of the tibial nerve secondary to accessory soleus muscle. After surgical excision of the accessory soleus muscle with no tarsal tunnel release, the patient presented with complete resolution of her manifestations continued free of symptoms for one and half year postoperatively. The accessory soleus muscle is a potential extrinsic cause for tibial nerve compression neuropathy.

LEVEL OF CLINICAL EVIDENCE

5.

Anatomical variation in the ankle and foot: from incidental finding to inductor of pathology. Part I: ankle and hindfoot

Accessory anatomical structures in the ankle and foot usually represent incidental imaging findings; however, they may also eventually represent a source of pathology, such as painful syndromes, degenerative changes, be the subject of overuse and trauma or appear as masses and cause compression syndromes or impingement.This review aims to describe and illustrate the imaging findings related to the presence of accessory ossicles and muscles in the ankle and hindfoot through different techniques, with special attention to those variants that associate factors of clinical relevance or that trigger challenges in the differential diagnosis.

An online catalog of muscle variants: Student perceptions of a new opportunity for self-directed learning

OBJECTIVE:

Muscle variants are common findings in dissection laboratories. These anomalous structures can be relevant in the diagnosis and management of certain conditions and therefore could be incorporated into anatomy curricula at chiropractic colleges. We aimed to create an online resource of muscle variants to facilitate student self-directed learning within this area of study.

METHODS:

At the time of their discovery during routine educational dissection, muscle variants included in the catalog were documented and subsequent case reports written. All content created for this resource, including photographs and videos, was hosted on the institution's learning management system. Students enrolled in our doctor of chiropractic program were invited to view the catalog and encouraged to leave feedback by completing an online survey.

RESULTS:

Student responses to Likert-style survey questions generally indicated high levels of satisfaction regarding the utility and features of the catalog. Open-ended and Likert-style survey questions were used to help guide the future directions of this developing resource. Concurrent anatomy students were not more likely to contribute to the catalog compared to students who had previously completed the university's anatomy course series ( p = .75, 2-tailed Fisher exact test).

CONCLUSION:

An online supplement to graduate-level gross anatomy courses can aid in the instruction of muscle variants by providing an opportunity for student self-directed learning. This resource will be updated continually and will be expanded on to include neurovascular and visceral variants. Student participation will be sought in developing future content to be included in this catalog.

Isolated rupture of the accessory soleus tendon: an original and confusing picture

The accessory soleus muscle is an uncommon congenital anatomical variant with a prevalence ranging from 0.7 to 5.5%. Although intermittent and exertional symptoms caused by this supernumerary muscle have been well documented, acute injuries have not. We present a case of an isolated rupture of the accessory soleus tendon with myotendinous retraction, mimicking clinically a "tennis leg." A 29-year-old woman sustained a hyperdorsal flexion injury of the right ankle with a severe and sudden pain in the middle part of the calf. Radiographs were normal and the diagnosis of "tennis leg" was clinically suspected. Ultrasound demonstrated bilateral accessory soleus muscles. On the symptomatic side, there was a complete isolated rupture of the accessory soleus tendon with myotendinous retraction. These findings were confirmed by magnetic resonance imaging (MRI), which showed no other abnormality. To our knowledge, this acute and misleading presentation has not been reported previously.

MR Imaging of Atraumatic Muscle Disorders

Atraumatic disorders of skeletal muscles include congenital variants; inherited myopathies; acquired inflammatory, infectious, or ischemic disorders; neoplastic diseases; and conditions leading to muscle atrophy. These have overlapping appearances at magnetic resonance (MR) imaging and are challenging for the radiologist to differentiate. The authors organize muscle disorders into four MR imaging patterns: (a) abnormal anatomy with normal signal intensity, (b) edema/inflammation, (c) mass, and (d) atrophy, highlighting each of their key clinical and imaging findings. Anatomic muscle variants, while common, do not produce signal intensity alterations and therefore are easily overlooked. Muscle edema is the most common pattern but is nonspecific, with a broad differential diagnosis. Autoimmune, paraneoplastic, and drug-induced myositis tend to be symmetric, whereas infection, radiation-induced injury, and myonecrosis are focal asymmetric processes. Architectural distortion in the setting of muscle edema suggests one of these latter processes. Intramuscular masses include primary neoplasms, metastases, and several benign masslike lesions that simulate malignancy. Some lesions, such as lipomas, low-flow vascular malformations, fibromatoses, and subacute hematomas, are distinctive, but many intramuscular masses ultimately require a biopsy for definitive diagnosis. Atrophy is the irreversible end result of any muscle disease of sufficient severity and is the dominant finding in disorders such as the muscular dystrophies, denervation myopathy, and sarcopenia. This imaging-based classification, in correlation with clinical and laboratory data, will aid the radiologist in interpreting MR imaging findings in patients with atraumatic muscle disorders. ^©RSNA, 2018.

Anatomical variations of flexor hallucis longus tendon increase safety in hindfoot endoscopy

PURPOSE

The flexor hallucis longus (FHL) tendon is the main anatomical landmark during hindfoot endoscopy, and anatomical variations related to the FHL can pose a risk to the tibial nerve and posterior tibial vessels during hindfoot endoscopy. The aim of this study was to determine the distance between the FHL tendon and the tibial neurovascular bundle in the posterior ankle joint when an anatomical variant of the FHL is present. The hypothesis was that the shortest distance between the tibial neurovascular bundle and the FHL tendon in the working area of the hindfoot endoscopy is increased when an anatomical variant of the FHL is present.

METHODS

A retrospective review was performed using consecutive ankle magnetic resonance imaging (MRI) scans obtained during 1 year. All scans with anatomical variations related to the FHL were included in the study. A control group including scans without anatomical variations was obtained for comparison. The shortest distance between the FHL tendon and the neurovascular tibial bundle was measured in both groups.

RESULTS

Three-hundred and fifty-five ankle MRIs were reviewed. 35 scans with anatomical variants of the FHL (9.8%) were found and comprised the study group that was compared to 35 scans without variants (control group). The mean distance from FHL to the neurovascular tibial bundle in the control group was 0.9 mm. The study group consisted of 18 cases with distal muscle belly insertion (5.1%), and 17 cases with an accessory tendon corresponding to a flexor digitorum accessorius longus (4.5%). In these subgroups, the mean distance from FHL to the neurovascular tibial bundle was 1.1 and 1.5 mm respectively. Overall this distance was found to be higher in the group with anatomical variants (1.3 mm) when compared to the control group (0.9 mm) (p < 0.05).

CONCLUSION

During hindfoot endoscopy, the presence of an anatomical variant related to the FHL tendon has proven safer anatomically than in its absence, due to the increased distance between the FHL tendon and the tibial neurovascular bundle in the working area. However, the minimal difference observed in safety distances still poses a major risk of injury during hindfoot endoscopic procedures in all cases.

Use of botulinum toxin type A in symptomatic accessory soleus muscle: first five cases

Symptomatic accessory soleus muscle (ASM) can cause exercise-induced leg pain due to local nerve/vascular compression, muscle spasm, or local compartment syndrome. As intramuscular injections of botulinum toxin type A (BTX-A) can reduce muscle tone and mass, we investigated whether local BTX-A injections relieve the pain associated with symptomatic ASM. We describe five patients presenting peri/retromalleolar exertional pain and a contractile muscle mass in the painful region. Com-pression neuropathy was ruled out by electromyo-graphic analysis of the lower limb muscles. Doppler ultrasonography was normal, excluding a local vascular compression. ASM was confirmed by magnetic resonance imaging. After a treadmill stress test, abnormal intramuscular pressure values in the ASM, confirmed the diagnosis of compartment syndrome only in one patient. All five patients received BTX-A injections in two points of the ASM. The treatment efficacy was evaluated based on the disappearance of exercise-induced pain and the resumption of normal physical and sports activities. After BTX-A injection, exertional pain disappeared and all five patients resumed their normal level of physical and sports performances. Neither side effects nor motor deficits were observed. BTX-A is well tolerated in patients with ASM and could be used as a new conservative therapeutic strategy for the treatment of symptomatic ASM before surgery.

Whole genome sequencing identifies ANXA3 and MTHFR mutations in a large family with an unknown equinus deformity associated genetic disorder

The aim of this study was to characterize a previously uncharacterized genetic disorder associated with equinus deformity in a large Chinese family at the genetic level. Blood samples were obtained and whole genome sequencing was performed. Differential gene variants were identified and potential impacts on protein structure were predicted. Based on the control sample, several diseases associated variants were identified and selected for further validation. One of the potential variants identified was a ANXA3 gene [chr4, c.C820T(p.R274*)] variant. Further bioinformatic analysis showed that the observed mutation could lead to a three-dimensional conformational change. Moreover, a MTHFR variant that is different from variants associated with clubfoot was also identified. Bioinformatic analysis showed that this mutation could alter the protein binding region. These findings imply that this uncharacterized genetic disorder is not clubfoot, despite sharing some similar symptoms. Furthermore, specific CNV profiles were identified in association with the diseased samples, thus further speaking to the complexity of this multigenerational disorder. This study examined a previously uncharacterized genetic disorder appearing similar to clubfoot and yet having distinct features. Following whole genome sequencing and comparative analysis, several differential gene variants were identified to enable a further distinction from clubfoot. It is hoped that these findings will provide further insight into this disorder and other similar disorders.

Accessory Soleus: A Case Report of Exertional Compartment and Tarsal Tunnel Syndrome Associated With an Accessory Soleus Muscle

An accessory soleus muscle is a rare anatomic variant that frequently presents as an asymptomatic soft tissue swelling in the posteromedial ankle. Less frequently, the anomalous muscle can cause pain and swelling with activity. We present the case of a 17-year-old male with exertional compartment syndrome and associated tarsal tunnel syndrome secondary to a very large accessory soleus muscle. After surgical excision, the patient was able to return to full activity with complete resolution of symptoms.

Accessory muscles around the foot and ankle presenting as chronic undiagnosed pain. An illustrative case report and review of the literature

The differential diagnosis of ankle pain is extensive. Pathology may be classified as intra- or extra-articular. Additionally, ankle pain may be traumatic or non-traumatic. One of the unusual differential diagnoses for pain in the ankle is an accessory muscle. Magnetic resonance imaging is the radiological investigation of choice. However, this is invariably reported as normal unless one specifically looks for an accessory muscle. The purpose of this report is to highlight important features of these muscles and to draw attention to this uncommonly reported condition.

Accessory soleus muscle: a case report and clinical applicability

Variations in leg muscle are uncommon. Literature on this subject is scarce, but when those variations are reported they may cause alterations in joint mechanics or cause some discomfort in the leg and foot. The accessory soleus muscle (ASM) is considered an unusual anatomical variation, with an incidence of 0.5-6.0% in the population through studies in cadavers. During routine preparation of study material in the dissection room of the anatomy laboratory of the Escola Superior de Ciências da Santa Casa de Misericórdia de Vitória/ES – Brazil, an ASM was found in the right inferior limb of a male cadaver fixed in 10% formalin. This supernumerary muscle was 3 cm wide, 9 cm long and 1 cm thick in its most voluminous part, in typical penniform fibers arrangement. It was located in the posteromedial region of the ankle, anterior to the Achilles tendon and posterior to the deep muscles of the leg compartment. Its anterior face covered the tibial nerve and the posterior tibial vessels, while its lower half was covered by the flexor retinaculum into the tarsal tunnel. Reports in the literature show possible compression of a neurovascular bundle because of its intimal position within the tarsal tunnel, which could result in ischemic compartment syndrome.

Posterior ankle impingement

Posterior ankle impingement is a common cause of chronic ankle pain and results from compression of bony or soft tissue structures during ankle plantar flexion. Bony impingement is most commonly related to an os trigonum or prominent trigonal process. Posteromedial soft tissue impingement generally arises from an inversion injury, with compression of the posterior tibiotalar ligament between the medial malleolus and talus. Posterolateral soft tissue impingement is caused by an accessory ligament, the posterior intermalleolar ligament, which spans the posterior ankle between the posterior tibiofibular and posterior talofibular ligaments. Finally, anomalous muscles have also been described as a cause of posterior impingement.

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.

Progressive limitation of knee flexion secondary to an accessory quinticeps femoris muscle in a child: a case report and literature review

We describe a symptomatic, progressive restriction of knee flexion due to an accessory quadriceps femoris in a nine-year-old girl. There was no history or findings of post-injection fibrosis, nor any obvious swelling of the affected quadriceps. At arthroscopy no intra-articular pathology was found. An accessory 'quinticeps femoris' was diagnosed by ultrasonography and MRI. Following excision of the muscle and tendon full flexion of the knee was regained and there was no recurrence of the contracture.

The co-existence of the gastrocnemius tertius and accessory soleus muscles

A bilateral gastrocnemius tertius muscle and a unilateral accessory soleus muscle were encountered during the routine educational dissection studies. The right gastrocnemius tertius muscle consisted of one belly, but the left one of two bellies. On the left side, the superficial belly of the gastrocnemius tertius muscle had its origin from an area just above the tendon of the plantaris muscle, the deep belly from the tendon of the plantaris muscle. The accessory soleus muscle originated from the posteromedial aspect of the tibia and soleal line of the tibia and inserted to the medial surface of the calcaneus. On the right side, the gastrocnemius tertius muscle had its origin from the lateral condyle of the femur, and inserted to the medial head of the gastrocnemius muscle. The co-existence of both gastrocnemius tertius and accessory soleus muscle has not, to our knowledge, been previously reported.

Accessory soleus in the athletes: literature review and case report of a massive muscle in a soccer player

Accessory soleus is a rare congenital anatomical variant, which may manifest in the second/third decade of life as an exertional ankle pain and swelling or as an asymptomatic postero-medial mass. The incidence of this condition ranges from 0.7 to 5.5%. Many treatment options have been described in literature, including conservative treatment, excision, fasciotomy, release and closure of blood supply. We report a symptomatic massive accessory soleus (17 x 5 x 4 cm) in an 18-year-old male semi-professional soccer player. Excision of the accessory soleus was performed. The patient went back to the game 3 months after surgery. The literature review stated that either fasciotomy or excision of the muscle produce good results in the athletes.

High association between accessory soleus muscle and Achilles tendonopathy

OBJECTIVE

This study investigated the association between accessory soleus muscle and abnormalities of the Achilles tendon.

MATERIALS AND METHODS

The authors reviewed 15 consecutive cases with a diagnosis of accessory soleus muscle from a computerized database of ankle magnetic resonance (MR) examinations reported between January 1998 and January 2007. On review, two cases were eliminated because of an incorrect initial diagnosis: One patient had a low lying soleus attachment to the Achilles tendon, while the other had a prominent flexor hallucis longus tendon partially obliterating Kager's fat. The remaining 13 cases with accessory soleus muscles were evaluated for Achilles tendon abnormalities.

RESULTS

There were 13 cases of accessory soleus muscles in 11 patients; two patients had bilateral accessory soleus muscles (the only study patients with bilateral MR examinations in our sample). There were five male and six female patients ranging from 15 to 81 years of age (mean 48). There were nine cases (69.2%) in which Achilles tendonopathy was associated with accessory soleus muscle, including tendonopathy of each Achilles tendon in the two patients with bilateral accessory muscles.

CONCLUSION

In our small patient population, there was a high association between accessory soleus muscle and Achilles tendonopathy.

Accessory soleus muscle in clubfoot deformity: a report in four feet

The commonest presentation of accessory soleus muscle is a swelling at the posteromedial aspect of the ankle in adolescents or young adults. Accessory soleus is rarely encountered in children undergoing surgical release for congenital clubfoot, and only a few isolated reports are available in the literature. The purpose of this study is to heighten awareness about the role of accessory soleus muscle in clubfoot deformity. Four cases of accessory soleus muscle in patients undergoing surgical release for clubfoot deformity are reported here in which, a distinct anomalous muscle deep to the tendoachilles was identified. Hindfoot varus and equinus persisted in each of these cases despite an adequate posteromedial soft tissue release, which could be corrected only on tenotomizing the tendon of the accessory soleus muscle at its insertion. An awareness about the accessory soleus muscle is important, particularly when non-operative methods of clubfoot management with tendoachilles tenotomy or limited surgery are employed. Failure to recognize this muscle if present in patients with congenital clubfoot may lead to persistent hindfoot deformity. A high index of suspicion should be maintained in cases in which hindfoot deformity persists despite an otherwise adequate soft tissue correction.

Symptomatic accessory soleus muscle: diagnosis and follow-up on magnetic resonance imaging

The accessory soleus muscle is a rare anatomical variant which, although congenital in origin, may manifest in the second and third decades of life as a painful ankle mass or an asymptomatic ankle soft tissue swelling. We report a symptomatic accessory soleus muscle in a 21-year-old male soldier that was diagnosed and followed-up on MRI. Initial MRI showed a mass with signal characteristics of normal muscle, but in an abnormal location. There was increased intrafascial fluid and perimuscular oedema around the accessory soleus muscle. Following conservative treatment, repeat MRI showed resolution of this intrafascial fluid collection and perimuscular oedema, concurrent with relief of the patient's painful symptoms.

The functional anatomy of Kager's fat pad in relation to retrocalcaneal problems and other hindfoot disorders

Kager's fat pad is a mass of adipose tissue occupying Kager's triangle. By means of a combined magnetic resonance imaging, ultrasound, gross anatomical and histological study, we show that it has three regions that are closely related to the sides of the triangle. Thus, it has parts related to the Achilles and flexor hallucis longus (FHL) tendons and a wedge of fat adjacent to the calcaneus. The calcaneal wedge moves into the bursa during plantarflexion, as a consequence of both an upward displacement of the calcaneus relative to the wedge and a downward displacement of the wedge relative to the calcaneus. During dorsiflexion, the bursal wedge is retracted. The movements are promoted by the tapering shape of the bursal wedge and by its deep synovial infolds. Fibrous connections linking the fat to the Achilles tendon anchor and stabilize it proximally and thus contribute to the motility of its tip. We conclude that the three regions of Kager's fat pad have specialized functions: an FHL part which contributes to moving the bursal wedge during plantarflexion, an Achilles part which protects blood vessels entering this tendon, and a bursal wedge which we suggest minimizes pressure changes in the bursa. All three regions contribute to reducing the risk of tendon kinking and each may be implicated in heel pain syndromes.

Anomaly of anatomical origin of soleus muscle: a mouse model

In the laboratory mouse, the soleus muscle arises at the head of the fibula and inserts via the Achilles tendon on the tuber calcanei together with the gastrocnemius muscle. During routine dissection of mice from the BXD recombinant inbred (RI) strains, we found that the soleus often originated from the lateral epicondyle of the femur instead of the head of the fibula. This soleus femoral attachment anomaly (SFAA) changes the soleus from being a single-joint to a two-joint muscle. The incidence of SFAA was 45% in the BXD38 RI strain. Bilateral inspection indicated that SFAA may be present unilaterally or bilaterally within an individual mouse. We explored the effect of SFAA on muscle weight in mice with unilateral expression. The weight of SFAA soleii was significantly less (P < 0.01) than that of the soleii with normal attachment by 6% (females) and 14% (males). Similar anatomical anomalies of the soleus muscle have been noted in humans. The mouse model will provide the means to explore the physiological consequences and genetic basis for such anomalies.

Le muscle soléaire accessoire

PURPOSE OF THE STUDY

Well known to anatomy specialists, the accessory soleus muscle was first demonstrated to be involved in painful syndromes in 1965 (Dunn). This supranumerary muscle situated in front of the calcaneum can be taken for a soft tissue tumor. The purpose of this work was to report a series of 21 patients with an accessory soleus muscle and to present the characteristic features, diagnostic methods, and treatment indications and modalities.

MATERIAL AND METHODS

This series included 20 patients (one symptomatic bilateral case), fourteen men and six women, mean age 25 years. Seventeen patients practiced sports and ten had had a prior operation. All patients complained of exercise-related pain. The physical examination was normal with the exception of a tumefaction, which was soft at rest and hard at triceps contraction against resistance, lying laterally to the Achilles tendon. We studied plain x-rays, ultrasound studies, computed tomographies, and electromyograms and later MRI which became the reference method to demonstrate the details of normal muscle structure. Ten patients (one bilateral case) were not particularly bothered by the supernumerary muscle. Functional treatment was given and provided patient satisfaction. For the other ten patients, who wished to continue their physical activities, two underwent fasciotomy (including our first case where fasciotomy was undertaken because a tumor was suspected) and eight underwent resection of the supranumerary muscle.

RESULTS

The patients were followed for 6 to 19 years. Outcome was very good in all patients who were free of pain and had complete joint movement with symmetrical muscle force. Normal sports activities were resumed.

DISCUSSION

The accessory soleus muscle is found in 10% of individuals. It is often asymptomatic. The muscle inserts on the anterior aspect of the soleus muscle or on the posterior aspect of the tibia or the muscles of the deep posterior compartment. It lies anterior to the calcaneal tendon and terminates on the calcaneal tendon or the superior or medial aspect of the calcaneus via fleshy fibers or a distinct tendon. Frequent in primates, this anatomic variant is present during embryological development. Its persistence depends on phylogenetic evolution. Among other hypotheses (exercise-induced intermittent claudication, compression of the tibial nerve, excessive tension on the nerve innervating the accessory soleus muscle), this supranumerary muscle is generally considered to be the cause of a localized compartment syndrome. Pain experienced during exercise is the only symptom regularly reported by patients. A careful examination is required to rule out another local cause. Besides tumefaction lateral to the Achilles tendon, often found bilaterally, there is no other clinical sign. Plain x-rays, ultrasound and computed tomography simply demonstrate a "mass" in front of the Achilles tendon. MRI is the examination of choice enabling confirmation of the muscle nature of the mass and ruling out the possible diagnosis of tumor. Since there is no risk of aggravation, surgical treatment can be avoided if there is no complaint. If the patient is seriously impaired, surgery can be proposed. In our opinion, complete resection of the supernumerary muscle is the safest solution and should be preferred over simple fasciotomy.

First report of an accessory popliteal muscle: detection with MRI

During an MRI examination of the knee in a 48-year-old patient suffering from degenerative changes of a partly resected medial meniscus and concomitant osteoarthritis of the knee joint, an unusual variant of an accessory muscle in the popliteal fossa was found. To our best knowledge this muscle has never been described before. Because of the close relationship to the popliteal muscle with regard to course and localisation in the deep popliteal fossa ventral to the popliteal artery, the term "accessory popliteal muscle" is proposed.

Ankle and foot disorders in skeletally immature athletes

As one of the most commonly injured areas in the immature athlete, the foot and ankle has many disorders. Knowledge of congenital and developmental abnormalities and possible injury patterns enables the clinician to correctly diagnose these disorders. Physical examination and appropriate use of imaging technology provide confirmation of the initial impression. As children and adolescents participate in sports with greater intensity, there is a higher incidence of overuse injuries that may have long-term implications.

Tarsal tunnel syndrome associated with an accessory muscle

Between 1986 and 1999, we surgically treated 41 patients (49 feet) with Tarsal Tunnel Syndrome (TTS) in whom seven (eight feet) were associated with an accessory muscle. An accessory flexor digitorum longus muscle was present in six patients, and an accessory soleus muscle was in one patient (both feet). Three of them were males and four females, with the mean age of 33.1 years (12 to 59 years). The mean interval from the onset of symptoms to operation was 7.5 months (range, six to nine months). All patients with an accessory muscle had a history of trauma or strenuous sporting activity. The diagnosis of TTS was made based on physical findings in all the patients (eight feet) and confirmed in five patients (six feet) by electrophysiological examination. Imaging examinations (radiography, ultrasonography, MRI) revealed abnormal bone and soft tissue lesions in and around the tarsal tunnel. Preoperative signs and symptoms disappeared average 4.1 months after decompression of the tibial nerve in addition to excision of the muscle. No functional deficit was observed at final follow-up (24 to 88 months).

Accessory soleus muscle as a cause of resistance to correction in congenital club foot: a case report

A 14-month-old female with bilateral clubfeet was initially treated by serial casting and percutaneous tenotomy of the Achilles tendon, bilaterally. Both clubfeet subsequently underwent surgical treatment with a posteromedial release through a Cincinnati incision. At surgery on one clubfoot, an accessory Soleus muscle was found anterior to the Achilles tendon with a distinct insertion on the upper surface of calcaneus, anterior and medial to the insertion of Achilles tendon. This accessory Soleus muscle may have been the cause of resistance to correction in this congenital clubfoot.

Asymptomatic accessory soleus muscle

The accessory soleus muscle has been infrequently seen and reported clinically. Most of the cases reported have been associated with symptomatology. Yet there are cases in which the patient presents with only asymptomatic swelling. Such a case is presented as well as a review of previously reported cases of the accessory soleus muscle.