Normal Anatomy and Compression Areas of Nerves of the Foot and Ankle: US and MR Imaging with Anatomic Correlation

Camera-based evaluation of deep breathing effects on plantar foot microcirculation - A pilot study on young healthy

BACKGROUND

Microvascular function, particularly of the plantar foot, reflects overall vascular health and is influenced by physiological oscillators such as heart rate, respiratory, myogenic, and neurogenic rhythms. Slow deep breathing modulates autonomic nervous system activity and affects peripheral microcirculation. This study investigates the effects of slow deep breathing on plantar foot perfusion using photoplethysmography imaging (PPGI).

METHODS

Twenty healthy young adults participated in a four-stage protocol: baseline, deep breathing test (DBT), and two recovery stages (REST1 and REST2). PPGI was used to measure changes in plantar foot perfusion, focusing on energy, amplitude, and phase synchronization within frequency bands corresponding to key physiological oscillators. Time-frequency analyses and advanced signal processing were applied to assess these parameters.

RESULTS

Significant increases in energy were observed in all frequency bands during DBT, with slow frequency oscillators (SFOs) maintaining elevated activity up to 5 min after DBT. Amplitude analysis revealed a significant decrease in the first and second harmonic components of the heart rate signals during DBT. Phase synchronization between medial and lateral foot regions improved for respiratory, myogenic, and neurogenic frequency bands during DBT, with myogenic synchronization persisting for up to 2.5 min after DBT.

CONCLUSIONS

Slow deep breathing enhances microvascular perfusion and synchronizes autonomic oscillators in healthy individuals. PPGI proved effective in capturing these dynamics, indicating its potential as a non-invasive tool for assessing autonomic and microvascular function. Future research should explore its applicability in detecting early autonomic or vascular dysfunction in clinical populations.

Intermittent flexor hallucis longus dislocation: ultrasound findings

We report a case of intermittent dislocation of the flexor hallucis longus at its passage in the retro-malleolar area, related to a post-traumatic detachment of the retrotalar pulley from the medial tubercle of the talus. High-resolution ultrasound depicted the anterior dislocation of the tendon during dynamic stress, by asking the patient to flex his hallux against the examiner resistance, with the ankle in slight dorsiflexion. The tendon normally relocated after the dynamic maneuver. Tendon dislocation was associated with a painful snap.

Subcutaneous injection of lidocaine around ischemic ankle provides safe and effective foot analgesia in patients with critical limb ischemia

OBJECTIVE

It is often difficult to alleviate foot pain associated with critical limb ischemia (CLI) using common analgesics. Neuraxial block is contraindicated in anticoagulant therapy. This study was designed to determine the response to subcutaneous injection of lidocaine around the network of peripheral nerves around the ankle in patients with CLI pain on anticoagulants and antiplatelets.

METHODS

Sixteen patients with CLI pain in the foot were enrolled in this double-blind placebo-controlled crossover study. Patients were randomized to receive either 2% lidocaine or saline via catheters inserted into the subcutaneous area around the ankle. After recurrence of pain, the patients were crossed over to receive the alternative treatment. Pain was assessed with a numerical rating scale (NRS) before and 15 min after injection. Patients used a descriptive scale to grade pain control and were asked to determine the duration of analgesia in each arm of the study.

RESULTS

No serious complications including protracted bleeding occurred. Lidocaine significantly decreased the NRS on movement from 10 (6, 10) [median (range)] to 2 (0, 10) (p < .001), and the differences in the Δ change in NRS between lidocaine and placebo were significant (p = .009). Of the 16 patients, 14 patients were very satisfied after lidocaine but only one described the same after saline. The effect of lidocaine and placebo lasted 11 (0, 28) and 1 (0, 22) h, respectively.

CONCLUSION

Subcutaneous injection of lidocaine around the ischemic ankle affectively alleviated pain in patients with CLI without serious adverse effects under anticoagulant therapy.

Ultrasound imaging of the femoral and saphenous nerves

Introduction

Iatrogenic and traumatic injuries to the femoral and saphenous nerves, and their branches are uncommon but can be a cause of clinically pertinent lower limb dysfunction and neuralgia. Despite this, direct sonographic imaging of these nerves is not commonly requested or performed.

Methods

A review of the literature regarding the detailed relative anatomy, sonographic technique to image these nerves and their branches and their normal and abnormal appearances was conducted.

Discussion

These nerves are often in the direct imaging field of many ultrasound examinations including the assessment of the groin and lower limb vasculature and musculoskeletal studies. They can become entrapped at certain points throughout their path, where particular attention should be provided to these nerves.

Conclusion

Improved knowledge regarding the sonographic imaging of the femoral and saphenous nerves and their branches can assist identification and discrimination between normal and abnormal appearances, and subsequent ultrasound-guided nerve blockades or radiofrequency ablations for pain management where required.

Magnetic Resonance Neurography of the Foot and Ankle

Peripheral neuropathies of the foot and ankle can be challenging to diagnose clinically due to concomitant traumatic and nontraumatic or degenerative orthopedic conditions. Although clinical history, physical examination, and electrodiagnostic testing comprised of nerve conduction velocities and electromyography are used primarily for the identification and classification of peripheral nerve disorders, MR neurography (MRN) can be used to visualize the peripheral nerves as well as the skeletal muscles of the foot and ankle for primary neurogenic pathology and skeletal muscle denervation effect. Proper knowledge of the anatomy and pathophysiology of peripheral nerves is important for an MRN interpretation.

High-resolution Ultrasound of the Foot and Ankle

High-resolution ultrasound (US) can be used to assess soft tissue abnormalities in the foot and ankle. Compared to MRI, it has lower cost, is widely available, allows portability and dynamic assessment. US is an excellent method to evaluate foot and ankle tendon injuries, ligament tears, plantar fascia, peripheral nerves, and the different causes of metatarsalgia.

[Superficial peroneal nerve entrapment: ultrasound-guided hydrodissection. A case report]

Peripheral nerve entrapment is an underdiagnosed pathology when it is not the most common syndromes such as carpal tunnel syndrome or cubital tunnel syndrome. The symptomatic lesion of the superficial peroneal nerve (SPN) has a low incidence, being its diagnosis sometimes complex. It is based on a exhaustive physical examination and imaging tests such as ultrasound (US) or magnetic resonance imaging (RMI). Conservative treatment may sometimes not be sufficient, requiring surgical techniques in refractory cases. We present a patient diagnosed with superficial peroneal nerve entrapment by ultrasound and diagnostic nerve block that was subsequently resolved by hydrodissection technique at the level of the deep crural fascia tunnel. The results were satisfactory with a complete resolution of the clinical process since the application of this technique.

Sonographic anatomy and technique to image the plantar digital nerves and aid identification of a Morton's neuroma

Introduction

The anatomy of the forefoot is complex, and the sonographic assessment to image the plantar digital nerves and exclude, diagnose or discriminate between a Morton's neuroma and intermetatarsal bursitis can be challenging.

Topic description and discussion

A good appreciation of the sonographic anatomy, technique, normal and abnormal appearances is required to undertake a sonographic assessment of the forefoot and its interspaces, particularly the plantar digital nerves. This is unpacked in this paper with associated pictorial aids. Muscles, tendons, and ligaments of the interspaces and the nearby metatarsophalangeal joints and their associated soft-tissue structures are helpful sonographic landmarks to guide imaging and assessment of the common and proper plantar digital nerves and the intermetatarsal bursa. These need to be appreciated from both dorsal and plantar sonographic approaches, in both short- and long-axis imaging planes.

Conclusion

Improved understanding of the anatomy and sonographic appearances of the interspace structures can enhance the sonographic assessment of the forefoot and improve diagnosis of a Morton's neuroma and/or intermetatarsal bursitis when present to guide patient management.

Common fibular nerve palsy due to the Fabella: A review

One of the most common nerve palsies - common fibular nerve palsy - can be caused by the variant small sesamoid bone in the posterolateral compartment of the knee joint known as the fabella. We compared and reviewed all reported cases of common fibular nerve palsy due to fabellae in the English literature. Compression can develop spontaneously or post-surgically (total knee arthroplasty). Symptoms progress rapidly to complete foot drop. Among all the cases reviewed, 68.42% were males with a median age of 39.39 years. Fabella compression was more common in the left common fibular nerve (CFN) (63.16%). Both big (23 × 20 × 16 mm) and small (5 × 5 mm) fabellae can be responsible for compression. While diagnosis can be problematic, the treatment (either surgical fabellectomy or conservative) is relatively easy and brings quick improvement.

Nerve entrapment syndromes of the lower limb: a pictorial review

Peripheral nerves of the lower limb may become entrapped at various points during their anatomical course. While clinical assessment and nerve conduction studies are the mainstay of diagnosis, there are multiple imaging options, specifically ultrasound and magnetic resonance imaging (MRI), which offer important information about the potential cause and location of nerve entrapment that can help guide management. This article overviews the anatomical course of various lower limb nerves, including the sciatic nerve, tibial nerve, medial plantar nerve, lateral plantar nerve, digital nerves, common peroneal nerve, deep peroneal nerve, superficial peroneal nerve, sural nerve, obturator nerve, lateral femoral cutaneous nerve and femoral nerve. The common locations and causes of entrapments for each of the nerves are explained. Common ultrasound and MRI findings of nerve entrapments, direct and indirect, are described, and various examples of the more commonly observed cases of lower limb nerve entrapments are provided.Critical relevance statement This article describes the common sites of lower limb nerve entrapments and their imaging features. It equips radiologists with the knowledge needed to approach the assessment of entrapment neuropathies, which are a critically important cause of pain and functional impairment.Key points• Ultrasound and MRI are commonly used to investigate nerve entrapment syndromes.• Ultrasound findings include nerve hypo-echogenicity, calibre changes and the sonographic Tinel's sign.• MRI findings include increased nerve T2 signal, muscle atrophy and denervation oedema.• Imaging can reveal causative lesions, including scarring, masses and anatomical variants.

The role of high-resolution ultrasound and MRI in the evaluation of peripheral nerves in the lower extremity

Lower extremity peripheral neuropathy is a commonly encountered neurologic disorder, which can lead to chronic pain, functional disability, and decreased quality of life for a patient. As diagnostic imaging modalities have improved, imaging has started to play an integral role in the detection and characterization of peripheral nerve abnormalities by non-invasively and accurately identifying abnormal nerves as well as potential causes of neuropathy, which ultimately leads to precise and timely treatment. Ultrasound, which has high spatial resolution and can quickly and comfortably characterize peripheral nerves in real time along with associated denervation muscle atrophy, and magnetic resonance neurography, which provides excellent contrast resolution between nerves and other tissues and between pathologic and normal segments of peripheral nerves, in addition to assessing reversible and irreversible muscle denervation changes, are the two mainstay imaging modalities used in peripheral nerve assessment. These two modalities are complimentary, and one may be more useful than the other depending on the nerve and location of pathology. Imaging must be interpreted in the context of available clinical information and other diagnostic studies, such as electrodiagnostic tests. Here, we offer a comprehensive overview of the role of high-resolution ultrasound and magnetic resonance neurography in the evaluation of the peripheral nerves of the lower extremity and their associated neuropathies.

Anatomical study of the medial calcaneal nerve using high-resolution ultrasound

OBJECTIVES

To determine whether high-resolution ultrasound (US) can identify the course and relations of the medial calcaneal nerve (MCN).

METHODS

This investigation was initially undertaken in eight cadaveric specimens and followed by a high-resolution US study in 20 healthy adult volunteers (40 nerves) by two musculoskeletal radiologists in consensus. The location and course of the MCN as well as its relationship to adjacent anatomical structures were evaluated.

RESULTS

The MCN was consistently identified by US along its entire course. The mean cross-sectional area of the nerve was 1 mm2 (range 0.5-2). The level at which the MCN branched from the tibial nerve was variable, located a mean of 7 mm (range - 7-60) proximal to the tip of the medial malleolus. At the level of the medial retromalleolar fossa, the MCN was located inside the proximal tarsal tunnel a mean of 8 mm (range 0-16) posterior to the medial malleolus. More distally, the nerve was depicted in the subcutaneous tissue at the surface of the abductor hallucis fascia with a mean direct distance to the fascia of 1.5 mm (range 0.4-2.8).

CONCLUSIONS

High-resolution US can identify the MCN at the level of the medial retromalleolar fossa, as well as more distally in the subcutaneous tissue at the surface of the abductor hallucis fascia. In the setting of heel pain, precise sonographic mapping of the MCN course may enable the radiologist to make diagnosis of nerve compression or neuroma, and perform selective US-guided treatments.

CLINICAL RELEVANCE STATEMENT

In the setting of heel pain, sonography is an attractive tool for diagnosing compression neuropathy or neuroma of the medial calcaneal nerve, and enables the radiologist to perform selective image-guided treatments such as diagnostic blocks and injections.

KEY POINTS

• The MCN is a small cutaneous nerve which rises from the tibial nerve in the medial retromalleolar fossa to the medial side of the heel. • The MCN can be depicted by high-resolution ultrasound along its entire course. • In the setting of heel pain, precise sonographic mapping of the MCN course may enable the radiologist to make diagnosis of neuroma or nerve entrapment, and perform selective ultrasound-guided treatments such as steroid injection or tarsal tunnel release.

Magnetic Resonance Neurography of the Foot and Ankle

Peripheral neuropathies of the foot and ankle can be challenging to diagnose clinically due to concomitant traumatic and nontraumatic or degenerative orthopedic conditions. Although clinical history, physical examination, and electrodiagnostic testing comprised of nerve conduction velocities and electromyography are used primarily for the identification and classification of peripheral nerve disorders, MR neurography (MRN) can be used to visualize the peripheral nerves as well as the skeletal muscles of the foot and ankle for primary neurogenic pathology and skeletal muscle denervation effect. Proper knowledge of the anatomy and pathophysiology of peripheral nerves is important for an MRN interpretation.

Comparing Clinical Examination and Radiological Evaluation in the Preoperative Diagnosis and Location of Symptomatic Interdigital (Morton's) Neuroma

This study investigates whether clinical examination is as sensitive as ultrasound and magnetic resonance imaging (MRI) in the diagnosis and localization of symptomatic interdigital neuroma. A retrospective cohort study was conducted at two tertiary centers on all consecutive patients who underwent excision by a single foot and ankle specialist surgeon for a presumed interdigital neuroma between January 2008 and December 2020. Investigators collected preoperative clinical findings, radiological investigations, and postoperative outcomes. Sensitivity and positive predictive values were calculated and Z-score for 2 populations proportions was performed. One hundred fourteen consecutive patients were operated on for 131 suspected interdigital neuroma. Thirteen patients were excluded due to lack of adequate clinical documentation. Of the remaining 101 patients with 118 suspected interdigital neuroma, 115 were confirmed histologically (97.5%). The sensitivity of clinical assessment to accurately diagnose and place an interdigital neuroma in the correct space was calculated as 96.5%. The most common preoperative clinical feature was pain (99.2%). The calculated sensitivity for ultrasound to accurately diagnose an interdigital neuroma was 83.6%, and to correctly locate neuroma was 79.5% respectively, which were both statistically different compared to clinical assessment (p value: <.001 and p value: <.001). The calculated sensitivity for MRI to accurately diagnose an interdigital neuroma was 93.6%, which was statistically different to clinical assessment (p value: .005). Preoperative clinical assessment has the highest sensitivity to accurately diagnose interdigital neuroma when compared to MRI and ultrasound. Preoperative clinical assessment has higher sensitivity to accurately locate interdigital neuroma when compared to ultrasound.

High-resolution Ultrasound of the Foot and Ankle

High-resolution ultrasound (US) can be used to assess soft tissue abnormalities in the foot and ankle. Compared to MRI, it has lower cost, is widely available, allows portability and dynamic assessment. US is an excellent method to evaluate foot and ankle tendon injuries, ligament tears, plantar fascia, peripheral nerves, and the different causes of metatarsalgia.

Nerve entrapment syndromes: detection by ultrasound

Nerve entrapment syndromes are commonly encountered in clinical practice. Accurate diagnosis and management require a knowledge of peripheral neuroanatomy and the recognition of key clinical symptoms and findings. Nerve entrapment syndromes are frequently associated with structural abnormalities of the affected nerve. Therefore, imaging allows the evaluation of the cause, severity, and etiology of the entrapment. High-resolution ultrasonography can depict early and chronic morphological changes within the entire nerve course and is therefore an ideal modality for diagnosing various nerve entrapment syndromes in different regions. This review article presents some of the most common types of nerve entrapment, with special focus on ultrasound imaging and key findings.

The diagnostic and therapeutic challenges of medial plantar neuropathy in jogger's foot: a case report

Jogger's foot is characterised by a neuropathic pain along the medial arch of the foot caused by compression of the medial plantar nerve. It is more common in runners, especially when there is an anatomical predisposition or some extrinsic factor that may exert compression on the nerve. This article presents the case of a 59-year-old man, who had pain and paraesthesia along the medial plantar arch of the left foot, lasting for several months. Despite having undergone some conservative treatments (plantar orthosis and physiotherapy) and minimal invasive procedures (cortico-anaesthetic injection and shockwave therapy) the symptoms persisted and amyotrophy of the abductor hallucis muscle became clinically evident. At this point, a magnetic resonance image was taken, showing compression of the medial plantar nerve at the intersection of the flexor hallucis longus and the flexor digitorum longus tendons. Ultrasound-guided treatment with pulsed radiofrequency of the medial plantar nerve was then proposed to try and modulate his chronic neuropathic pain. After the procedure, the patient reported immediate relief of the symptoms, which were maintained over 6 months of follow up after the procedure. This case report illustrates a rare and frequently misdiagnosed cause of midfoot pain and its management using electromagnetic modulation of peripheral nerves by pulsed radiofrequency. This seems to be an effective technique, with long-lasting results.

An overview of common peroneal nerve dysfunction and systematic assessment of its relation to falls

PURPOSE

Compression of the peroneal nerve is recognized as a common cause of falls. The superficial course of the peroneal nerve exposes it to trauma and pressure from common activities such as crossing of legs. The nerve can be exposed also to distress due to metabolic problems such as diabetes. The purpose of our manuscript is to review common peroneal nerve dysfunction symptoms and treatment as well as provide a systematic assessment of its relation to falls.

METHODS

We pooled the existing literature from PubMed and included studies (n = 342) assessing peroneal nerve damage that is related in any way to falls. We excluded any studies reporting non-original data, case reports and non-English studies.

RESULTS

The final systematic assessment included 4 articles. Each population studied had a non-negligible incidence of peroneal neuropathy. Peroneal pathology was found to be consistently associated with falls.

CONCLUSION

The peroneal nerve is an important nerve whose dysfunction can result in falls. This article reviews the anatomy and care of the peroneal nerve. The literature review highlights the strong association of this nerve's pathology with falls.

To Be or Not to Be (A Morton's/Interdigital Neuroma): That Is the Question-A Case Series of Lateral Forefoot Pain Localized to the Proper Digital Nerve of the Fifth Toe

We present 2 cases where the initial history and examination were similar to a Morton's/interdigital neuroma. In both cases, however, diagnostic ultrasound revealed symptomatic snapping of the proper digital nerve of the fifth toe. The anatomy of the proper digital nerve of the fifth toe may predispose it to a snapping phenomenon. Clinical awareness of this atypical cause of forefoot pain can help guide the diagnosis and treatment in those patients with persistent and refractory lateral forefoot pain and paresthesias.

Ultrasound-guided treatment of Morton's neuroma

Morton’s neuroma is a painful lesion of the interdigital nerve, usually at the third intermetatarsal space, associated with fibrotic changes in the nerve, microvascular degeneration, and deregulation of sympathetic innervation. Patients usually present with burning or sharp metatarsalgia at the dorsal or plantar aspect of the foot. The management of Morton’s neuroma starts with conservative measures, usually with limited efficacy, including orthotics and anti-inflammatory medication. When conservative treatment fails, a series of minimally invasive ultrasound-guided procedures can be employed as second-line treatments prior to surgery. Such procedures include infiltration of the area with a corticosteroid and local anesthetic, chemical neurolysis with alcohol or radiofrequency thermal neurolysis. Ultrasound aids in the accurate diagnosis of Morton’s neuroma and guides the aforementioned treatment, so that significant and potentially long-lasting pain reduction can be achieved. In cases of initial treatment failure, the procedure can be repeated, usually leading to the complete remission of symptoms. Current data shows that minimally invasive treatments can significantly reduce the need for subsequent surgery in patients with persistent Morton’s neuroma unresponsive to conservative measures. The purpose of this review is to present current data on the application of ultrasound for the diagnosis and treatment of Morton’s neuroma, with emphasis on the outcomes of ultrasound-guided treatments.

Topography of muscular branches of the superficial fibular nerve based on anatomical preparation of human foetuses

BACKGROUND

The progress of pediatric surgery and increasingly better diagnosis of fetal defects require detailed knowledge of human developmental anatomy. Precise knowledge of the anatomy of innervation of the lower extremities corresponds to this subject and is not only cognitive but also clinically important. The aim of this study was to analyse the anatomy of the topography of the muscular branches of the superficial fibular nerve (NPS) in the prenatal period, which will fill a gap in the literature.

METHODS

The analysis was carried out on 207 human foetuses aged from the 113th day to 222nd day of foetal life. The study material is a part of the collection of the Division of Normal Anatomy of Wroclaw Medical University. The study incorporated the following methods: anthropological, preparational and image acquisition which was acquired with the use of high-resolution digital camera. Statistical analysis was carried out with the use of STATISTICA package.

RESULTS

Based on the research results the number of muscle branches of the examined nerve was determined. It was shown that in more than half of the cases the two nerve branches are responsible for Peroneus Longus innervation and in about 90% of cases one branch is responsible for Peroneus Brevis innervation. Based on the obtained data a unique, new typology of distribution of these branches was created. It has been shown that the bipinnate type is the most common in the examined fetal population. The presence of statistically significant differences in the frequency of occurrence of individual innervation patterns depending on sex and body side were excluded (p > 0.05). There were also no statistically significant changes in the frequency of occurrence of individual types of NPS branch distribution according to fetal age (p > 0.05).

CONCLUSIONS

The created unique typology of NPS branch distribution based on extensive preparation material is an important supplement to the anatomical knowledge and at the same time, due to the peripheral and superficial location of the described structures, it has a relevant clinical significance.

Ultrasound Imaging of the Deep Peroneal Nerve

Ultrasound is considered an excellent imaging modality to evaluate the nerves of the limbs. The deep peroneal nerve (DPN) is one of the terminal branches of the common peroneal nerve. The DPN may be affected by various disorders, which may be clinically challenging to show. This Pictorial Essay reviews the normal ultrasound anatomy of the DPN and presents disorders that may involve the nerve and its main branches along its course, from proximal to distal.

Clinics in diagnostic imaging (205). Baxter's neuropathy

A 48-year-old woman presented with chronic right heel pain and paraesthesia over the foot. Magnetic resonance imaging of the right foot demonstrated isolated atrophy of the abductor digiti minimi. A diagnosis of Baxter's neuropathy was made and the patient was managed successfully via surgical release. We describe the clinical and radiological features of Baxter's neuropathy and, with brief examples, outline other causes of chronic heel pain.

An MRI study of the tibial nerve in the ankle canal and its branches: a method of multiplanar reformation with 3D-FIESTA-C sequences

Background

The visualization of the tibial nerve and its branches in the ankle canal is helpful for the diagnosis of local lesions and compression, and it is also useful for clinical observation and surgical planning. The aim of this study was to investigate the feasibility of three-dimensional dual-excitation balanced steady-state free precession sequence (3D-FIESTA-C) multiplanar reformation (MPR) display of the tibial nerve and its branches in the ankle canal.

Methods

The subjects were 20 healthy volunteers (40 ankles), aged 22–50 years, with no history of ankle joint disease. The 3D-FIESTA-C sequence was used in the 3.0 T magnetic resonance equipment for imaging. During scanning, each foot was at an angle of 90° to the tibia. The tibial nerve of the ankle canal and its branches were displayed and measured at the same level through MPR.

Results

Most of the tibial nerve bifurcation points were located in the ankle canal (57.5%), few bifurcation points (42.5%) were located at the proximal end of the ankle canal, and none of them were found away from the distal end. The bifurcation between the medial plantar nerve and the lateral plantar nerve was on the line between the tip of the medial malleolus and the calcaneus, and it’s angle ranged between 6° and 35°. In MPR images, the display rates of both the medial calcaneal nerve and the subcalcaneal nerve were 100%, and the starting point of the subcalcaneal nerve was always at the distal end of the starting point of the medial calcaneal nerve. In 55% of cases, there were more than two medial calcaneal nerve innervations.

Conclusion

The 3D-FIESTA-C MPR can display the morphological features and positions of the tibial nerve and its branches and the bifurcation point’s projection position can be marked on the body surface. This method not only benefited the imaging diagnosis of the tibial nerve and branch-related lesions in the ankle canal, but it also provided a good imaging basis to plan a clinical operation of the ankle canal and avoid surgical injury.

Plantar or Palmar Tactile Augmentation Improves Lateral Postural Balance With Significant Influence from Cognitive Load

Although it seems intuitive to address the issue of reduced plantar cutaneous feedback by augmenting it, many approaches have adopted compensatory sensory cues, such as tactile input from another part of the body, for multiple reasons including easiness and accessibility. The efficacy of the compensatory approaches might be limited due to the cognitive involvement to interpret such compensatory sensory cues. The objective of this study is to test the hypothesis that the plantar cutaneous augmentation is more effective than providing compensatory sensory cues on improving postural regulation, when plantar cutaneous feedback is reduced. In our experiments, six healthy human subjects were asked to maintain their balance on a lateral balance board for as long as possible, until the balance board contacted the ground, for 240 trials with five interventions. During these experiments, subjects were instructed to close their eyes to increase dependency on plantar cutaneous feedback for balancing. Foam pad was also added on the board to emulate the condition of reduced plantar cutaneous feedback. The effects of tactile augmentation from the foot sole or the palm on standing balance were tested by applying transcutaneous electrical stimulation on calcaneal or ulnar nerve during the balance board tests, with and without a cognitively-challenging counting task. Experimental results indicate that the plantar cutaneous augmentation was effective on improving balance only with cognitive load, while the palmar cutaneous augmentation was effective only without cognitive load. This result suggests that the location of sensory augmentation should be carefully determined according to the attentional demands.

Anatomical study and branching point of neurovascular structures at the medial side of the ankle

Nerve entrapment and blood circulation impairment associated with the medial side of the ankle are not uncommon. The purpose of this study was to describe the anatomical basis of neurovascular structures of the medial ankle which comprised the number, origin, branching pattern, and branching point. Forty feet of fresh cadavers were examined by using 2 reference lines: the malleolar-calcaneal (MC) and navicular-calcaneal (NC) axes. We recorded number, origin, length of the 2 axes, the locations and widths of neurovascular structures on MC and NC axes, the branching point of neurovascular structures, and the branching pattern of neurovascular structures was recorded and was separated into 5 types. The posterior tibial nerve (PTN) bifurcated to plantar and calcaneal nerves and branched proximally to the tarsal tunnel (TT). The posterior tibial artery bifurcated to plantar and calcaneal arteries and branched inferiorly to PTN and within the TT. The calcaneal nerves and arteries had more variation of number and origin. The most common branching point of calcaneal nerves and arteries is within the TT, except the medial calcaneal nerve. It branched proximally to the TT. The anatomical knowledge from this study is important for the diagnosis and treatment of clinicians.

MRI appearance of jogger's foot

OBJECTIVE

To characterize the MRI findings present in patients with clinically proven or suspected jogger's foot.

MATERIALS AND METHODS

Ten years of medical charts in patients clinically suspected of having jogger's foot and who had MRI studies completed were identified utilizing a computer database search. Six study cases were identified. The MRI examinations of the study cases and an age- and gender-matched control group were reviewed in a blinded fashion by two musculoskeletal radiologists. Size and signal intensity of the medial plantar nerve were measured and characterized. The medial foot musculature was assessed for acute or chronic denervation changes.

RESULTS

The medial plantar nerve was found to have moderately increased T2 signal compared with normal skeletal muscle in 3/6 study group cases and markedly increased T2 signal in the remaining 3/6 cases. In all control cases, the nerve was reported to have T2 signal equal or minimally higher than normal skeletal muscle. The mean total size of the medial plantar nerve was significantly larger in the study group when compared with that in the control group at all measured locations (p < 0.04).

CONCLUSIONS

Abnormal thickness and T2 hyperintensity of the medial plantar nerve centered at the master knot of Henry are characteristic MRI findings in patients with jogger's foot when compared with control subjects. Muscular denervation changes may also be seen, most commonly in the flexor hallucis brevis muscle.

Relationship Between Sensory Symptoms, Mulder's Sign, and Dynamic Ultrasonographic Findings in Morton's Neuroma

BACKGROUND

Morton's neuroma (MN) is often a diagnostic dilemma lacking a gold standard set of diagnostic criteria. Advanced imaging of MN is evolving including ultrasonography. The current study aimed to analyze the relationship between ultrasonographic findings and symptoms, clinical data, and operative findings in a subgroup of patients.

METHODS

We evaluated physical examination, ultrasonographic findings, symptoms, and in a subgroup, the operative findings for Morton's neuroma. We analyzed the symptoms, the findings on physical examination, and ultrasonography data and performed a statistical correlation between them. A total of 175 patients were seen for suspected Morton's neuroma during the last 7 years.

RESULTS

Neuropathic pain of the toes was reported in 63% of patients. Presence of ultrasonographic findings suggesting Morton's neuroma was observed in 77% of cases. A mild significant relationship between neuropathic pain and positive ultrasonographic findings was observed. We found a strong correlation between ultrasonographic and clinical evaluation, but more than half with clinical negative Morton's neuroma had positive findings at ultrasonography. In the subgroup of operatively treated patients (n = 44) surgery confirmed Morton's neuroma in all patients who had positive ultrasonography findings.

CONCLUSIONS

The current study suggests that the association of ultrasonographic evaluation and clinical evaluation can be very useful for the management of Morton's neuroma. Our study could help with the development of a multiperspective approach in the diagnosis of Morton's neuroma.

LEVEL OF EVIDENCE

Level II, prospective cohort survey study.

Morton's neuroma: review of anatomy, pathomechanism, and imaging

Morton's neuroma is a commonly encountered cause of forefoot pain, which may limit weight-bearing activities and footwear choices. Although the aetiology and pathomechanism of this condition is controversial, the histological endpoint is well established as benign perineural fibrosis of a common plantar digital nerve, typically within the third intermetatarsal space. The diagnosis of Morton's neuroma is mainly based on characteristic symptoms and clinical findings, but may be confirmed by ultrasonography. Although ultrasound is a highly accurate diagnostic tool for Morton's neuroma, it is subject to interoperator variability due to differences in technique and level of experience. In this paper, the authors review the anatomy of the common plantar digital nerves and surrounding structures in the forefoot, which are deemed relevant to the understanding of Morton's neuroma, especially from a sonographic point of view. Several theories of the pathomechanism of Morton's neuroma are briefly discussed. The main purpose of this article is to illustrate the ultrasound techniques for evaluating Morton's neuroma and performing ultrasound-guided corticosteroid injections.

ACR Appropriateness Criteria® Chronic Foot Pain

Chronic foot pain is a frequent clinical complaint, which can significantly impact the quality of live in some individuals. These guidelines define best practices with regards to requisition of imaging studies based on specific clinical scenarios, which have been grouped into different variants. Each variant is accompanied by a brief description of the usefulness, advantages, and limitations of different imaging modalities. The present narrative is the result of an exhaustive assessment of the available literature and a thorough review process by a panel of experts on Musculoskeletal Imaging. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Ultrasound-guided diagnostic deep peroneal nerve blocks prior to potential neurectomy: a retrospective review

OBJECTIVE

To describe our technical and preliminary clinical experience with ultrasound-guided diagnostic deep peroneal nerve (DPN) blocks for patients considering deep peroneal neurectomy.

MATERIALS AND METHODS

Retrospective analysis of ultrasound-guided diagnostic DPN blocks performed in the anterior lower leg in patients pursuing deep peroneal neurectomy for foot pain not directly attributable to the DPN. Patient age, sex, foot laterality, diagnosis, nerve block complications, location of the DPN with respect to vascular landmarks in the lower leg, pain relief from nerve block, and pain relief from neurectomy (if performed) were recorded.

RESULTS

Twenty-six DPN blocks were performed for 25 feet, of which a majority had pain attributable to midfoot osteoarthritis (22/25). Variable DPN locations with respect to vascular landmarks in the lower leg were observed, including lateral to the anterior tibial artery (12/25), anterior to the artery (5/25), medial to the artery (3/25), lateral to the lateral paired vein (4/25), and 1-cm lateral to the artery (1/25). After DPN blocks, patients reported pain relief in 22/25 feet. Of the eleven patients who proceeded to have a deep peroneal neurectomy, ten reported improved foot pain.

CONCLUSION

Diagnostic deep peroneal nerve blocks for patients considering deep peroneal neurectomy for denervation therapy should be performed in the anterior lower leg where the anterior tibial vessels serve as anatomic landmarks. Those who perform DPN blocks with ultrasound guidance should be aware of variable DPN position with respect to the vascular landmarks.

Ultrasound-guided Therapeutic Injection and Cryoablation of the Medial Plantar Proper Digital Nerve (Joplin's Nerve): Sonographic Findings, Technique, and Clinical Outcomes

RATIONALE AND OBJECTIVES

The medial plantar proper digital nerve, also called Joplin's nerve, arises from the medial plantar nerve, courses along the medial hallux metatarsophalangeal joint, and can be a source of neuropathic pain due to various etiologies, following acute injury including bunion surgery and repetitive microtrauma. We describe our clinical experience with diagnostic ultrasound assessment of Joplin's neuropathy and technique for ultrasound-guided therapeutic intervention including both injection and cryoablation over a 6-year period.

MATERIALS AND METHODS

Retrospective review of all diagnostic studies performed for Joplin's neuropathy and therapeutic Joplin's nerve ultrasound-guided injections and cryoablations between 2012 and 2018 was performed. Indications for therapeutic injection and cryoablation, were recorded. Studies were assessed for sonographic abnormalities related to the nerve and perineural soft tissues. Post-treatment outcomes including immediate pain scores, clinical follow-up, and periprocedural complications were documented.

RESULTS

Twenty-four ultrasound-guided procedures were performed, including 15 perineural injections and nine cryoablations. With respect to sonographic abnormalities, nerve thickening (33%) and perineural hypoechoic scar tissue (27%) were the most common findings. The mean pain severity score prior to the therapeutic injection was 6.4/10 (range 4-10) and 0.25/10 (range 0-2) following the procedure; mean follow-up was 26.2 months (range 3-63 months). All of the cryoablation patients experienced sustained pain relief with a mean length follow-up of 3.75 months (range 0.2-10 months).

CONCLUSION

Therapeutic injection of Joplin's nerve is a safe and easily performed procedure under ultrasound guidance, with high rates of immediate symptom improvement. For those experiencing a relapse or recurrent symptoms, cryoablation offers an effective secondary potential treatment option.

Benign peripheral nerve sheath tumor of digit versus major-nerve: Comparison of MRI findings

Objective

To compare the symptoms and magnetic resonance imaging (MRI) findings between digital peripheral nerve sheath tumor (PNST) and major-nerve PNST.

Methods

A total 36 cases with benign PNSTs (16 digital, 20 major-nerve) were enrolled. Chief complaint and Tinel sign were reviewed. Five classic MRI features of PNST, the signal intensity (SI), the enhancement, and the shape of tumor were evaluated on MRI.

Results

Half of each group showed tenderness. Tinel sign was less frequent in digital PNST (12.5%) than major-nerve PNST (95.0%, P < 0.001). Split fat sign, entering and exiting nerve, target sign, and thin hyperintense rim were only observed in major-nerve PNST (P = <0.001, <0.001, 0.492, and 0.002, respectively). Fascicular sign was found in digital PNSTs (31.3%), but more frequent in major-nerve PNST (P < 0.001). In digital PNSTs, mild hyperintense SIs (56.2%) on T1-weighted images (T1-WI) was noted, but none in major-nerve PNST (P < 0.001). Both groups showed hyperintense SIs on T2-WI (P = 0.371). Homogeneity on T2-WI was noted in 43.8% of digital PNSTs, but none in major-nerve PNSTs (P = 0.004). Both groups showed heterogeneous enhancement (P = 0.066), but four (25%) digital PNSTs showed homogeneous enhancement. Lobulated shape was noted in 50% of digital PNSTs but none of major-nerve PNSTs (P = 0.001). Digital nerve was involved at 81.3% of digital PNSTs. Three foot cases showed unusual manifestations: bone destruction, skin thickening, and subungual location.

Conclusion

In digital PNSTs, Tinel sign is not commonly found and classic MRI findings is insufficient. In addition, some digital PNSTs show different SI and enhancement from major-nerve PNSTs. However, digital soft tissue tumor involving digital neurovascular bundle and especially representing a fascicular sign should be considered the possibility of a digital PNST.

Painful Foot Disorders in the Geriatric Population: A Narrative Review

Painful foot disorders are highly prevalent among older adults causing a significant impact on mobility, function, and risk of falls. Despite its significance, foot pain is often interpreted as a normal part of aging and relatively ignored by health care providers as well as by the older people themselves. Accurate diagnosis of the cause of foot pain is possible for most cases via clinical evaluation without a costly workup. Clinicians should consider, not only musculoskeletal pathologies but also vascular and neurological disorders in older patients with foot pain. Fortunately, most patients improve with physiatric, nonoperative interventions involving biomechanical analysis, function-oriented rehabilitation programs and therapeutic exercise, the use of proper footwear and orthoses, and selected percutaneous interventions, as indicated. In this review, we discuss the physiologic changes of the aging foot relevant to foot pain, the impact of painful foot disorders on function and other key outcomes, and principles of diagnosis and intervention. We also briefly describe painful foot disorders of the older people commonly encountered in a physiatric practice.

Communications between the superficial and deep fibular nerves in the foot: An anatomical and electrophysiological study

INTRODUCTION

The deep fibular sensory nerve can be recorded to evaluate for peripheral nerve injury; however, it can be challenging in some individuals. Anatomic variation could account for some of this difficulty. Cadaver dissection and electrophysiological testing were used to characterize deep and superficial fibular sensory nerve supply to the foot.

MATERIALS AND METHODS

Nineteen feet from 15 (8 males and 7 females) cadavers were dissected to identify the deep fibular nerves (DFNs) and superficial fibular nerves (SFNs). Sensation to the first dorsal web space was tested electrophysiologically in 101 participants (31 males and 70 females) with an age range of 18-47 years with stimulation over both DFNs and SFNs.

RESULTS

Eleven of the 19 (58%) cadaver limbs had a communication between SFNs and DFNs in the dorsum of the foot. A reliable sensory response was recorded in the first dorsal web space in 88% of the limbs tested. Deep fibular stimulation alone produced a response in 34% of the limbs, while superficial fibular stimulation alone produced a response in 10% of the limbs. A separate response with stimulation of both the DFNs and SFNs was recorded in 44% of the limbs.

CONCLUSIONS

A functional superficial to deep fibular sensory communication is present in a significant portion of the population. Those with the communication may not have the isolated sensory loss that would be expected in the first dorsal web space in conditions impacting the DFNs.

Advanced Ankle and Foot Sonoanatomy: Imaging Beyond the Basics

Ankle/foot pain is a common complaint encountered in clinical practice. Currently, due to the complex anatomy, the diagnosis and management of the underlying musculoskeletal disorders are extremely challenging. Nowadays, high-resolution ultrasound has emerged as the first-line tool to evaluate musculoskeletal disorders. There have been several existing protocols describing the fundamental sonoanatomy of ankle/foot joints. However, there are certain anatomic structures (e.g., Lisfranc ligament complex or Baxter nerve) which are also clinically important. As they are rarely elaborated in the available literature, a comprehensive review is necessary. In this regard, the present article aims to brief the regional anatomy, illustrate the scanning techniques, and emphasize the clinical relevance of the ankle/foot region.

Minimally invasive tenodesis for peroneus longus tendon rupture: A case report and review of literature

BACKGROUND

Peroneal tendon disorders are common causes of lateral hindfoot pain. However, total rupture of the peroneal longus tendon is rare. Surgical treatment for this condition is usually a side-to-side tenodesis of the peroneal longus tendon to the peroneal brevis tendon. While the traditional procedure involves a long lateral curved incision, this approach is associated with damage to the lateral soft tissues (up to 24% incidence).

CASE SUMMARY

A 50-year-old female had developed pain at the lateral aspect of the hindfoot 1 mo after an ankle sprain while walking in the street. Previous treatments were anti-inflammatory drugs, ice, rest and Cam-walker boot. At physical exam, there was pain and swelling over the course of the peroneal tendons. Ankle instability and cavovarus foot deformity were ruled out. Eversion strength was weak (4/5). Imaging showed complete rupture of the peroneal longus tendon associated with a sharp hypertrophic peroneal tubercle. Surgical repair was indicated after failure of conservative treatment (physiotherapy, rest, analgesics, and ankle stabilizer). A less invasive approach was performed for peroneal longus tendon debridement and side-to-side tenodesis to the adjacent peroneal brevis tendon, with successful clinical and functional outcomes.

CONCLUSION

Peroneus longus tendon tenodesis can be performed through a less invasive approach with preservation of the lateral soft tissue integrity.

Chronic Lower Leg Pain in Athletes: Overview of Presentation and Management

BACKGROUND

Athletes with chronic lower leg pain present a diagnostic challenge for clinicians due to the differential diagnoses that must be considered.

PURPOSE/QUESTIONS

We aimed to review the literature for studies on the diagnosis and management of chronic lower leg pain in athletes.

METHODS

A literature review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). The PubMed, Scopus, and Cochrane library databases were searched, and articles that examined chronic lower leg pain in athletes were considered for review. Two independent reviewers conducted the search utilizing pertinent Boolean operations.

RESULTS

Following two independent database searches, 275 articles were considered for initial review. After the inclusion and exclusion criteria were applied, 88 were included in the final review. These studies show that the most common causes of lower leg pain in athletes include medial tibial stress syndrome, chronic exertional compartment syndrome, tibial stress fractures, nerve entrapments, lower leg tendinopathies, and popliteal artery entrapment syndrome. Less frequently encountered causes include saphenous nerve entrapment and tendinopathy of the popliteus. Conservative management is the mainstay of care for the majority of cases of chronic lower leg pain; however, surgical intervention may be necessary.

CONCLUSIONS

Multiple conditions may result in lower leg pain in athletes. A focused clinical history and physical examination supplemented with appropriate imaging studies can guide clinicians in diagnosis and management. We provide a table to aid in the differential diagnosis of chronic leg pain in the athlete.

Diagnosis and Successful Management of an Unusual Presentation of Chronic Foot Pain Using Positron Emission Tomography/Magnetic Resonance Imaging and a Simple Surgical Procedure

A 61-year-old man presented with chronic dorsal foot pain of 9 years that worsened with ambulation. Conventional diagnostic imaging and medical workup were unrevealing, and ankle arthrodesis had been recommended by an orthopedic surgeon for pain relief. Instead, the patient participated in a clinical imaging trial designed for identifying pain generators using whole-body fluorodeoxyglucose (18F-FDG) positron emission tomography/magnetic resonance imaging (PET/MRI). The scan revealed not only high 18F-FDG uptake at the site of pain, but also a hematoma and an inflamed, fibrotic, ruptured plantaris muscle. The fibrotic plantaris likely altered biomechanics with walking, explaining why symptoms worsened with activity. A simple tenotomy of the plantaris tendon was performed to decouple ankle movement from the plantaris injury, resulting in pain relief. This case illustrates the potential of whole-body 18F-FDG PET/MRI to better localize pain generators.

Forefoot Pain in the Lesser Toes: Anatomical Considerations and Magnetic Resonance Imaging Findings

Various conditions may result in forefoot pain. Magnetic resonance (MR) imaging allows accurate assessment of many of these conditions. We provide an overview of forefoot disorders divided into bones, capsule and plantar plate, musculotendinous structures, neurovascular structures, and subcutaneous tissue. We review normal anatomical features as well as MR imaging findings of common disorders.

Ankle and Foot Ultrasound: Reliability of Side-to-Side Comparison of Small Anatomic Structures

OBJECTIVES

In sonography of clinically relevant small structures of the ankle and foot, the healthy contralateral side can be used as a reference to identify subtle abnormalities. Intrasubject side-to-side variability must be minimal. The aim of this study was to assess the reliability of side-to-side sonographic evaluation of small structures of the ankle and foot.

METHODS

Thirty healthy volunteers were prospectively studied. Small structures of the ankle and foot were evaluated bilaterally by 2 musculoskeletal radiologists in separate sessions. The deep peroneal nerve, superior extensor retinacula, calcaneofibular ligament, superior peroneal retinacula, tibialis posterior tendon, tibial nerve, Achilles tendon, plantaris tendon, plantar fascia, and sural nerve were considered. To assess intra- and interreader agreements, 30 (100%) examinations were repeated. A nonparametric statistic was used.

RESULTS

Data were not normally distributed (P > .001). Intrareader agreement was k = 0.67 (95% confidence interval, 0.57-0.78) and interreader agreement was k = 0.73 (95% confidence interval, 0.68-0.77). The mean values and standard deviation for all the structures were 0.36 ± 1.85 mm. The overall coefficient of variation was 18.5%. The intraclass correlation coefficient was 0.93 (95% confidence interval, 0.92-0.94).

CONCLUSIONS

In ankle and foot sonography, the healthy contralateral side can be used as a reference during a real-time musculoskeletal ultrasound evaluation of small structures.

Partial anterior tunnel syndrome: a retrospective analysis of ultrasound findings in four surgically proven cases

We present the cases of four patients (two men and two women, mean age of 48.5 years) with surgically confirmed partial anterior tarsal syndrome, diagnosed by ultrasound. All patients reported pain in the dorsal aspect of the forefoot radiating to the first intermetatarsal space. Ultrasound showed compression of the medial branch of the deep fibular nerve by the extensor hallucis brevis tendon at the level of the Lisfranc joint, associated with a hypoechoic neuroma. The ultrasound allowed a correct diagnosis to be obtained, which was not evident from clinical examination or by standard radiographs (four patients) or MRI (three patients). Surgery confirmed the sonographic findings, and all patients showed complete recovery.

Superficial course of the medial plantar nerve: case report

The medial and lateral plantar nerves are branched from the tibial nerve and move to the tip of the toes. A variation of medial plantar nerve was found on the left side of a 78-year-old Korean male cadaver. The tibial nerve was divided into the lateral and medial plantar nerves beneath the plantar flexor. The medial plantar nerve passed deep to plantar aponeurosis and superficial to the flexor digitorum brevis. It gave off a common plantar digital nerve and then divided into three proper plantar digital nerves near the metatarsal bases. In this article, we report a superficial course of the medial plantar nerve and describe its unique morphology and discuss the clinical significance of this variation.

Sonographically Guided Plantaris Tendon Release: A Cadaveric Validation Study

BACKGROUND

The plantaris tendon (PT) has been implicated in the pathogenesis of symptoms in a subset of patients with Achilles region pain syndromes and traditionally has been managed via open surgical resection. Although the PT can be visualized on ultrasound, a minimally invasive technique for sonographically guided PT release has not been formally described.

OBJECTIVE

To validate a technique to perform sonographically guided PT release in an unembalmed cadaveric model.

DESIGN

Prospective, cadaveric laboratory investigation.

SETTING

Procedural skills laboratory in a tertiary medical center.

SUBJECTS

Twenty unembalmed cadaveric knee-ankle-foot specimens (10 right, 10 left) obtained from 16 donors (6 male, 10 female) ages 55-96 years (mean 82.6 years) with body mass indexes of 14.1-33.2 kg/m² (mean 23.3 kg/m² ).

METHODS

After simulated local anesthesia and sonographically guided hydrodissection of the plantaris tendon-Achilles tendon interval, a single experienced operator performed sonographically guided PT release on each specimen using an in-plane, lateral-to-medial approach, a commercially available, disposable 3.0-mm hook knife, and either a 17-5 MHz or 15-7 MHz linear array transducer. Each specimen was subsequently dissected to assess for PT release and iatrogenic injury.

MAIN OUTCOME

Status of the PT, Achilles tendon, and regional neurovascular structures as determined by dissection.

RESULTS

All 20 PT releases were completed in a single attempt through a 3- to 5-mm incision. Dissection confirmed complete PT release in all specimens without damage to the adjacent Achilles tendon or regional neurovascular structures.

CONCLUSION

Sonographically guided PT release is technically feasible and can be performed while avoiding injury to the Achilles tendon and regional neurovascular structures. Additional research is warranted to further define the role of sonographically guided PT release in patients with suspected PT-mediated Achilles region pain syndromes.

LEVEL OF EVIDENCE

IV.

A review of main anatomical and sonographic features of subcutaneous nerve injuries related to orthopedic surgery

Lesion to subcutaneous nerves is a well-known risk of orthopedic surgery and a significant cause of postoperative pain and dissatisfaction in patients. High-resolution ultrasound can be used to visualize the vast majority of small subcutaneous nerves of the upper and lower limbs. Ultrasound detects nerve abnormalities such as focal hypoechoic thickening, stump neuroma, and scar encasement, and provides information not only about the peripheral nerve itself but also about its relationship to adjacent anatomical structures. The purpose of this review is to provide an overview of the anatomy of the main subcutaneous nerves damaged during orthopedic surgery, recall at-risk procedures, and offer useful anatomic landmarks to help the sonographer identify and follow the nerves when an iatrogenic lesion is suspected.

CT and MR Imaging of the Postoperative Ankle and Foot

A variety of surgical procedures exist for repair of both traumatic and degenerative osseous and soft-tissue pathologic conditions involving the foot and ankle. It is necessary for the radiologist to be familiar with these surgical procedures, so as to assess structural integrity, evaluate for complicating features, and avoid diagnostic pitfalls. Adequate interpretation of postoperative changes often requires access to surgical documentation to evaluate not only the surgery itself but the expected timeline for resolution of normal postoperative changes versus progressive disease. Appropriate use of surgical language in radiology reports is another important skill set to hone and is instrumental in providing a high-quality report to the referring surgeons. The pathophysiology of a myriad of surgical complaints, beginning from the Achilles tendon and concluding at the plantar plate, are presented, as are their common appearances at computed tomography and magnetic resonance imaging. Commonly encountered entities include Achilles tendon tear, spastic equinus, nonspastic equinus, talar dome osteochondral defect, tarsal tunnel syndrome, plantar fasciitis, pes planovalgus, pes cavovarus, peroneal tendinosis, lateral ligament complex pathology, Morton neuroma, plantar plate tear, and metatarsophalangeal joint instability. Computer-generated three-dimensional models are included with many of the procedures to provide a more global view of the surgical anatomy. Correlation with intraoperative photographs is made when available. When appropriate, discussion of postoperative complications, including entities such as infection and failure of graft integration, is presented, although a comprehensive review of postoperative complications is beyond the scope of this article. Notably absent from the current review are some common foot and ankle procedures including hallux valgus and hammertoe corrections, as these are more often evaluated radiographically than with cross-sectional imaging. ^©RSNA, 2016.