MR imaging in tarsal tunnel syndrome.

Magnetic resonance imaging was used to demonstrate the normal anatomy of the tarsal tunnel in two volunteers and to evaluate 33 feet in 27 patients with tarsal tunnel syndrome. The tarsal tunnel is a fibroosseous channel extending from the ankle to the midfoot, through which the medial tendons and the posterior tibial neurovascular bundle pass. Tarsal tunnel syndrome is a compression neuropathy of the posterior tibial nerve or one of its branches and may be caused by a variety of pathologic lesions. Magnetic resonance imaging demonstrated a mass lesion in five feet, dilated veins or varicosities in eight feet, fracture or soft tissue injury in five feet, fibrous scar in two feet, flexor hallucis longus tenosynovitis in six feet, and abductor hallucis muscle hypertrophy in one foot. Six feet were normal on MR imaging. The findings of MR imaging were confirmed in 17 of 19 patients that went to surgery. Magnetic resonance is useful for localizing lesions within the tarsal tunnel and for determining the lesion extent and relationship to the posterior tibial nerve and its branches.     

MR imaging of the carpal tunnel: normal anatomy and preliminary findings in the carpal tunnel syndrome

MR imaging was performed through the carpal tunnel in 18 wrists of nine normal volunteers and compared with cryomicrotome sections from cadaver wrists. MR reliably imaged the flexor retinaculum and carpal bones and thus defined the borders of the carpal tunnel. In all cases the median nerve was seen as an ovoid structure of moderate signal intensity and was easily distinguished from the flexor tendons of the hands running in the carpal tunnel. The tendons were separated from each other by their tendon sheaths, and this allowed for identification of the various tendons. Anatomic variations encountered in the normal volunteers included anomalous positioning of the origin of the lumbrical muscles within the carpal tunnel in two, persistent median arteries in two, and interposition of the median nerve between the flexor pollicis longus and the superficial flexor tendon to the index finger in one. Preliminary observations in 10 wrists of patients with carpal tunnel syndrome include segmental and diffuse swelling of the median nerve in six, distortion of the nerve in one, and thickening of the tendon sheaths in one. We conclude that MR imaging accurately and reliably displays the normal anatomy of the carpal tunnel and can detect morphologic changes in patients with carpal tunnel syndrome.     

MR imaging of flexor digitorum accessorius longus

Objective The flexor digitorum accessorius longus muscle (FDAL), an anomalous muscle about the ankle, has recently been implicated in tarsal tunnel syndrome. The purpose of this study is to document the prevalence of the FDAL, its MR appearance and its relation to the neurovascular bundle in the tarsal tunnel. Design and patients The prevalence of the FDAL was determined from 100 ankle MR examinations in asymptomatic individuals. The appearance of the FDAL was summarized from 20 examples of FDAL: six gathered from the asymptomatic group and 14 acquired from a group of randomly collected cases of patients with ankle complaints. Results The prevalence of the FDAL was 6%, calculated from the group of 100 asymptomatic individuals. Possessing a dominant fleshy component in the tarsal tunnel, the FDAL accompanies the posterior neurovascular bundle as it descends the ankle. Conclusion The FDAL is encountered in 6% of asymptomatic individuals. Its prominent fleshy component in the tarsal tunnel and its close proximity to the posterior tibial neurovascular bundle readily differentiate the FDAL from other medial anomalous muscles on MR imaging. Received: 29 September 1998 Revision requested: 6 November 1998 Revision received: 30 November 1998 Accepted: 30 November 1998     

Posterior tibial nerve entrapment at the ankle

Compression of the posterior tibial nerve of the ankle, also known as tarsal tunnel syndrome (TTS), is being seen withincreasing frequency in athletes, particularly runners. For this reason, it behooves the sports medicine professional to be well informed about this condition. TTS is caused by either extrinsic or intrinsic pressure on the posterior tibial nerve or its terminal branches. The syndrome, although analogous to carpal tunnel syndrome, is much less common. The most common symptoms of TTS are numbness and burning pain in the medial heel and foot. The condition is often difficult to differentiate from plantar fasciitis. Electrodiagnostic studies, including nerve conduction studies and electromyography, help confirm the diagnosis. Conservative measures are usually unsuccessful, and surgical decompression of the tarsal tunnel is generally regarded as the treatment of choice.     

MR imaging findings of entrapment of the flexor hallucis longus tendon

OBJECTIVE: In this retrospective study, we describe the MR imaging patterns of various causes of flexor hallucis longus tendon entrapment. CONCLUSION: Entrapment of the flexor hallucis longus tendon may be due to an enlarged os trigonumtarsitarsi, calcaneal fracture, and soft-tissue scar. These disorders have characteristic imaging findings that may be revealed on MR imaging.     

Anatomic relations between the median nerve and flexor tendons in the carpal tunnel: MR evaluation in normal volunteers

To ascertain the dynamic changes between the median nerve and flexor tendons in the carpal tunnel, MR images of 16 wrists in eight volunteers were studied in flexion, extension, and neutral positions. T1-weighted axial images, 600/20 (TR/TE) were obtained with the wrists straight, extended at 45 degree, and flexed at 45 degree. Each scan was evaluated with regard to positional changes of the median nerve and flexor tendons in the carpal tunnel as well as alterations in nerve shape. In the neutral position, the median nerve was found in one of two standard positions: either anterior to the superficial flexor tendon of the index finger or interposed more posterolaterally between this tendon and the flexor pollicis longus. During extension, the nerve always maintained or assumed an anterior position between the superficial index finger flexor and the flexor retinaculum, while the flexor tendons moved posteriorly. With flexion, the tendons shifted anteriorly toward the retinaculum, and the median nerve was found in one of three positions. It either remained in its anterior position between the superficial index finger flexor and retinaculum or became interposed between the superficial flexor tendons of the index finger and thumb or middle finger and ring finger. Nerve shape varied with its position. Anteriorly positioned nerves were flattened in the anteroposterior plane between the tendon and flexor retinaculum; this was greatest with flexion and least with extension. Interposed nerves were flattened in the mediolateral plane or rounded in configuration. In conclusion, the alignment of the median nerve in the carpal tunnel, its shape, and its relationship to the flexor tendons were variable and dependent on wrist positioning. These findings may explain why certain wrist motions, flexion in particular, predispose a person to carpal tunnel syndrome.     

Tendons in the plantar aspect of the foot: MR imaging and anatomic correlation in cadavers

Objective: The purpose of this anatomic imaging study was to illustrate the normal complex anatomy of tendons of the plantar aspect of the ankle and foot using magnetic resonance (MR) imaging with anatomic correlation in cadavers. Design: Seven fresh cadaveric feet (obtained and used according to institutional guidelines, with informed consent from relatives of the deceased) were studied with intermediate-weighted fast-spin-echo MR imaging. For anatomic analysis, cadaveric specimens were sectioned in 3-mm-thick slices in the coronal and axial planes that approximated the sections acquired at MR imaging. Results: The entire courses of the tendons into the plantar aspect of the foot were analyzed. The tibialis posterior tendon has a complex distal insertion. The insertions in the navicular, second, and third cuneiforms bones were identify in all cases using axial and coronal planes. A tendinous connection between the flexor hallucis longus and the flexor digitorum longus tendons was identified in five of our specimens (71%). The coronal plane provided the best evaluation. The peroneus longus tendon changes its direction at three points then obliquely crosses the sole and inserts in the base of the first metatarsal bone and the plantar aspect of the first cuneiform. Conclusions: MR imaging provides detailed information about the anatomy of tendons in the plantar aspect of the ankle and foot. It allows analysis of their insertions and the intertendinous connection between the flexor hallucis longus and the flexor digitorum longus tendons.     

Tendon injuries of the foot and ankle.

Tendon injuries are often caused by direct trauma or overuse. Pathology may consist of inflammatory lesions external to the tendon sheath or inflammation of either the peritenon, sheath, or tendon. This article reviews the diagnosis and treatment of injuries to the peroneal, peroneus brevis, peroneus longus, anterior tibial, flexor hallucis longus, and posterior tibial tendons.     

Intermittent dislocation of the flexor hallucis longus tendon

Dislocation of the flexor hallucis longus tendon is an exceptional occurrence. To our knowledge, this is the first case ever reported of an intermittent dislocation in a 17-year-old woman; she was a synchronised swimmer. She consulted for a right internal retro-malleolar syndrome. Voluntary "snap" was triggered by a mechanism which combined maximal ankle dorsiflexion and interphalangeal plantar flexion of the toes. Non-enhanced dynamic helical CT and axial MRI were performed, which revealed the dislocation of the right flexor hallucis longus tendon outside the posterior intertubercular talar groove. Static and dynamic imaging would appear to be required to make this uncommon diagnosis.     

Os trigonum tarsi syndrome. Role of magnetic resonance

INTRODUCTION: The os trigonum tarsi is an accessory bone of the foot localized posterolateral to the lateral tubercle of talus. It is usually an asymptomatic condition. However, particular activities such as ballet, soccer, or football may cause repeated stress and chronic microtraumas to the hindfoot, resulting in the os trigonum syndrome. Pain is typically localized anterior to the Achilles tendon; nevertheless, diagnosis may be very difficult because other conditions may show the same symptoms. Radiography can only demonstrate the os trigonum and its morphostructural changes, while MR imaging can also depict associated soft tissue damage. We report on 9 cases of os trigonum tarsi syndrome studied with MR imaging. MATERIAL AND METHODS: Nine patients with the os trigonum tarsi syndrome were submitted to MRI. All the examinations were performed with the patients in supine recumbency with the injured foot in neutral position and then in forced plantar flexion. Axial and sagittal T1 SE, T2* GE and FIR images were acquired. We evaluated os trigonum location and shape, signal intensity of bone, cartilages and adjacent soft tissues, and possible associated tendon injuries. RESULTS: No changes were found in the os trigonum location and shape. Signal intensity changes were seen in 2/9 cases. Particularly, a small area of very high signal intensity, due to necrosis, was depicted on the talar aspect in 1 case; a subchondral spot of slightly increased signal intensity, with a low-signal outline, was seen on the calcanear aspect in another case. Disruption of the cartilaginous synchondrosis between the accessory navicular bone and the posterior tibial aspect was observed in 7/9 patients. Tenosynovitis of the flexor hallucis longus was associated in 6/9 patients. Pseudoarthrosis with irregular bone margins and high-signal spots within the cartilage was found in 3 cases. Finally, fluid effusion surrounding the os trigonum and adjacent soft tissues was always detected. DISCUSSION AND CONCLUSIONS: The os trigonum syndrome may result from chronic microtraumas. Indeed, forced plantar flexion may cause os trigonum compression between the posterior aspect of the tibial malleolus and the calcaneus, with disruption of the synchondrosis with the lateral tubercle of talus. Joint inflammation may be associated with possible development of pseudoarthrosis. Other possible complications are related to vascular changes which may lead to bone necrosis. Furthermore, the particular anatomical site of the os trigonum may sometimes cause compression to the flexor hallucis longus tendon, resulting in severe tenosynovitis. MR imaging allows complete morphostructural assessment because it depicts the margins and the signal intensity of bone and ligaments on the 3 spatial planes. Particularly, sagittal T2 images best demonstrate the cartilage changes indicating synchondrosis disruption. This condition may cause abnormal mobility of the accessory bone with possible impingement with the posterior aspect of the tibia, or hypomobility due to pseudoarthrosis. Forced plantar flexion acquisitions are particularly useful in this condition because they can demonstrate the mechanism of injury.     

Diagnostic and therapeutic ankle tenography: outcomes and complications

OBJECTIVE: The purpose of our study was to evaluate tenography complications and outcomes in a large series. MATERIALS AND METHODS: Of 144 tenograms obtained consecutively from May 5, 1995, to March 17, 1997, 111 were located for at least a 6-month follow-up; 65 were posterior tibial, 39 peroneal, two anterior tibial, three flexor digitorum longus, and two flexor hallucis longus tenograms. Tenography was performed fluoroscopically with contrast material and anesthetic followed by steroid placement into tendon sheaths. RESULTS: Of 65 patients undergoing posterior tibial tenography, 31 (48%) had complete or near-complete symptom resolution; 17 (26%) had no relief. Seventeen patients (26%) had initial relief with the subsequent return of pain to the pretenography level. Of 39 patients undergoing peroneal tenography, 18 (46%) had complete or near-complete symptom resolution; 10 (26%) had no and 11 (28%) had initial relief with subsequent pretenography pain return. Of three patients undergoing flexor digitorum longus tenography, one had complete, one had no, and one had initial relief with complete pretenography pain return. One of two patients who underwent flexor hallucis longus tenography had no relief; the other had initial relief with complete pain return. Two patients who underwent anterior tibial tenography had complete pain relief. We found no correlation between degree of tenosynovitis shown radiographically and therapeutic improvement with anesthetic and steroid injection. Tenography complications included one posterior tibial tendon rupture (0.89%) and 14 patients with skin discoloration at the tendon sheath injection site. CONCLUSION: Forty-seven percent of surgical candidates whose condition was refractory to conservative therapy had complete or near-complete prolonged symptom relief after tenography. In appropriate patients, tenography is excellent therapy for tenosynovitis. Certain precautions make complications rare.     

Ultrasound of the tarsal tunnel: Normal and pathological imaging features

Tarsal tunnel syndrome is a condition that is caused by compression of the tibial nerve or its associated branches. Diagnosis is based on clinical findings but imaging is performed to exclude a cause of compression, identified in 60 to 80% of cases. Ultrasound is a useful examination because of its high spatial resolution and ability to rapidly perform an axial survey of the nerves. The ultrasound imaging features of the tarsal tunnel are described. The etiologies and different types are illustrated through a review of clinical cases.     

Anatomical variations within the deep posterior compartment of the leg and important clinical consequences.

The management of musculoskeletal conditions makes up a large part of a sports medicine practitioner's practice. A thorough knowledge of anatomy is an essential component of the armament necessary to decipher the large number of potential conditions that may confront these practitioners. To cloud the issue further, anatomical variations may be present, such as supernumerary muscles, thickened fascial bands or variant courses of nerves and blood vessels, which can themselves manifest as acute or chronic conditions that lead to significant morbidity or limitation of activity. There are a number of contentious areas within the literature surrounding the anatomy of the leg, particularly involving the deep posterior compartment. Conditions such as chronic exertional compartment syndrome, tibial periostitis (shin splints), peripheral nerve entrapment and tarsal tunnel syndrome may all be affected by subtle anatomical variations. This paper primarily focuses on the deep posterior compartment of the leg and uses the gross dissection of cadaveric specimens to describe definitively the anatomy of the deep posterior compartment. Variant fascial attachments of flexor digitorum longus are documented and potential clinical sequelae such as chronic exertional compartment syndrome and tarsal tunnel syndrome are discussed.     

Posterior ankle impingement syndrome: MR imaging findings in seven patients

PURPOSE: To report the magnetic resonance (MR) imaging findings in seven patients with posterior ankle impingement (PAI) syndrome. MATERIALS AND METHODS: Seven patients-three ballet dancers, one badminton player, one soccer player, one hockey player, and one construction worker-who presented with posterior ankle pain were assessed with MR imaging. Their clinical records and imaging studies were reviewed. The MR imaging studies were assessed for the presence of abnormal bone marrow signal intensity, osseous lesions, and soft-tissue abnormalities. RESULTS: One patient was treated surgically. In all patients, MR imaging demonstrated abnormal bone marrow signal intensity in the os trigonum and/or lateral talar tubercle, consistent with bone contusions. Two patients had a fragmented os trigonum or lateral tubercle, and two had a pseudoarthrosis of the posterolateral talus. Increased signal intensity was seen with distention of the posterior recess of the tibiotalar joint in two patients and with distention of the posterior recess of the subtalar joint in four patients. Three patients had fluid accumulation in the flexor hallucis longus tendon sheath. CONCLUSION: Bone contusions of the lateral talar tubercle and os trigonum are prevalent MR imaging findings of PAI syndrome. MR imaging clearly depicts the osseous and soft-tissue abnormalities associated with PAI syndrome and is useful in the assessment of this condition.     

Endoscopic assisted posterior tibial tendon reconstruction for stage 2 posterior tibial tendon insufficiency

Posterior tibial tendon insufficiency is the commonest cause of adult onset flatfoot deformity. The treatment of stage 2 posterior tibial tendon insufficiency is still controversial. Different combination of open procedures of tendon transfer, calcaneal osteotomy and hindfoot arthrodesis has been described. We describe an endoscopic approach of posterior tibial tendon reconstruction. By means of anterior and posterior tibial tendon tendoscopies, the medial half of the anterior tibial tendon is then transferred to the posterior tibial tendon. The construct is then augmented by side-to-side anastomosis with flexor digitorum longus tendon. This is supplemented with subtalar arthroereisis with a bioresorbable arthroereisis implant.     

Medial subtalar arthroscopy: a cadaveric study of the tarsal canal portal

Purpose

To study the safety of the tarsal canal portal in medial subtalar arthroscopy.

Methods

Twenty-three fresh frozen foot and ankle specimens were divided into two groups with different orientation of the portal tract. Three types of tarsal canal portals were identified. The relationships of the metal rod and the flexor digitorum longus tendon and the posterior neurovascular bundle were studied.

Result

In group A, a type 1 tarsal canal portal tract was established in seven specimens, a type 2 portal tract in three specimens, and a type 3 portal tract in two specimens. In group B, a type 1 portal tract was established in ten specimens and a type 2 portal tract in one specimen. No type 3 portal tract was established in group B. There was no statistical significance demonstrated for establishment of a type 1 portal tract and “non type 1” (type 2 or 3) portal tract in group A and group B. The average shortest distance between the rod and the posterior tibial neurovascular bundle was 7 mm in group A and 9 mm in group B.

Conclusions

This study provides the anatomic basis for the establishment of the tarsal canal portal. There is a risk of injury to the flexor digitorum longus tendon and the posterior tibial neurovascular bundle with the tarsal canal portal, and it should be used with great caution.     

Carpal tunnel syndrome: diagnosis with high-resolution sonography.

OBJECTIVE. Carpal tunnel syndrome is characterized by typical anatomic changes that can be shown with high-resolution sonography. To determine whether these findings are reliable and can be used to establish the diagnosis, sonograms of patients with the disease were compared with sonograms obtained in patients with normal wrists. Also compared were sonograms and MR images obtained in the patients with carpal tunnel syndrome. SUBJECTS AND METHODS. Twenty wrists in 18 consecutive patients with clinical symptoms of carpal tunnel syndrome and with abnormal nerve conduction studies were examined with real-time sonography and MR imaging. The sonograms and MR images were evaluated quantitatively by two unbiased observers with regard to the size and shape of the median nerve and the palmar bowing of the flexor retinaculum. A t test was used to compare these data with those from previous sonographic studies of 28 normal wrists. Correlation coefficients for the measurements obtained with sonography and with MR were calculated. The relative accuracies of different diagnostic criteria for the diagnosis of carpal tunnel syndrome were assessed by using receiver-operating-characteristic analytical techniques. RESULTS. Characteristic findings on both MR and CT scans of the 20 wrists with carpal tunnel syndrome included swelling of the median nerve in the proximal part of the carpal tunnel in 16 wrists, flattening of the median nerve in the distal part of the carpal tunnel in 13 wrists, and increased palmar bowing of the flexor retinaculum in nine wrists. Comparison with the data of 28 normal wrists proved that these findings were significant (p less than .01 to p less than .001). Receiver-operating-characteristic analysis showed that the discrimination between wrists in normal subjects and in patients with carpal tunnel syndrome achieved with each of the three diagnostic criteria was not significantly different. Measurements of the size and flattening of the median nerve obtained from sonograms were similar to those on MR images, whereas sonography was less accurate for measuring the palmar bowing of the flexor retinaculum. CONCLUSION. We conclude that the results of sonography are reliable, and that the diagnosis of carpal tunnel syndrome can be established on the basis of sonographic findings.     

Ankle tenography: a key to unexplained symptomatology. Part I: Normal tenographic anatomy

Fifty cadaver ankles were examined with ankle tenography. The normal tenographic appearance of the peroneus longus and brevis, posterior tibial, flexor digitorum longus, flexor hallucis longus, anterior tibialis, extensor hallucis longus, and extensor digitorum longus tendons and sheaths are described and illustrated for clinical reference. The baseline measurements and demonstration of the normal radiographic appearance of these tendons should assist in the evaluation of hindfoot foot disability and ankle pain.     

改良微创胫后神经减压术治疗跗管综合征

目的探讨改良微创胫后神经减压手术（显微镜结合关节镜技术）治疗跗管综合征。方法采用独创的单切口微创胫后神经减压手术对跗管综合征患者进行手术治疗,术中采用与屈肌支持带和拇展肌之间的平行于屈肌支持带的直切口,在显微镜和关节镜下同时对胫后神经主干及其分支进行满意松解,同时显著减轻了手术损伤。结果患者足底疼痛麻木症状均明显缓解120侧,缓解14侧患肢,麻木缓解28侧,缓解程度达85%以上,胫神经传导速度明显上升。结论微创胫后神经减压手术为跗管综合征的治疗提供了一条有效的新途径。     

Carpal tunnel: MR imaging. Part II. Carpal tunnel syndrome

The magnetic resonance (MR) images of 14 wrists of patients with carpal tunnel syndrome (CTS) were studied. Four general findings visible regardless of the cause of CTS included swelling of the median nerve, best evaluated at the level of the pisiform bone; flattening of the median nerve, most reliably judged at the hamate level; palmar bowing of the flexor retinaculum, best visualized at the level of the hamate bone; and increased signal intensity of the median nerve on T2-weighted images. Findings related to cause were tendon sheath edema in traumatic tenosynovitis, synovial hypertrophy in rheumatoid tenosynovitis, a ganglion cyst, and excessive amount of fat within the carpal tunnel, a persistent median artery, and a large adductor pollicis muscle. Knowledge of these findings may permit more rational choice of treatment. In four cases in which symptoms persisted after surgery, findings valuable in explaining or predicting the failure included incomplete incision of the flexor retinaculum, excessive fat within the carpal tunnel, persistent neuritis of the median nerve, and development of neuromas.