Advanced Ankle and Foot Sonoanatomy: Imaging Beyond the Basics

A systematic review of posterior pilon variant fractures

Posterior pilon variant ankle fractures (PPVF) are a unique subtype of posterior malleolar fractures which have been a source of controversy and confusion in recent years. There has not been a thorough literature review previously written on the topic. Database searches of PubMed and Embase were conducted from inception until June 2023. The key words included "pilon variant," "posterior pilon variant," and "posterior pilon" fractures. Outcomes were evaluated by union time, rates of delayed union, nonunion, malunion, and complication. A total of 15 articles relevant to surgical repair of pilon variant fractures were included in the literature review. The unique mechanism of injury has been reported to involve both rotational and axial forces, leading to involvement of the posterior and medial aspects of the distal tibia. Pilon variant fractures can be suspected by several characteristics on radiographs and have a high confirmation rate via CT images. Multiple systems have been proposed to classify this fracture pattern, but there is no consensus on the ideal classification system. Surgically, direct fixation has shown better short-term clinical outcomes versus indirect fixation or no fixation. PPVF have a distinct fracture pattern involving the posterior and medial columns of the distal tibial plafond, and results from a mechanism intermediate to rotational and axial forces. These fractures are more severe than tri-malleolar fractures due to increased rates of articular impaction and incongruity. Future classification systems should focus on joint surface area and the tibial pilon column involved to avoid confusion with less severe posterior malleolar fractures.

EURO-MUSCULUS/USPRM Dynamic Ultrasound Protocols for Ankle/Foot

ABSTRACT

In this dynamic scanning protocol, ultrasound examination of the ankle is described using various maneuvers to assess different conditions. Real-time patient examination and scanning videos are used for better simulation of daily clinical practice. The protocol is prepared by several/international experts in the field of musculoskeletal ultrasound and within the umbrella of European Musculoskeletal Ultrasound Study Group in Physical and Rehabilitation Medicine/Ultrasound Study Group of the International Society of Physical and Rehabilitation Medicine.

Anterior talofibular ligament's superior fascicle as a cause of ankle microinstability can be routinely identified by ultrasound

PURPOSE

Chronic pain can affect up to 40% of patients after ankle inversion sprains. The current hypothesis to explain this high percentage of chronic pain is a partial/total rupture of anterior talofibular ligament (ATFL) superior fascicle, a structure that has recently been described as intra-articular and as having a different function than ATFL's inferior fascicle. This has created the need for diagnosing ATFL superior and inferior fascicles independently. Therefore, the objective of this study is to investigate if the ATFL's superior fascicle can be visualized on ultrasound, and to describe its ultrasonographic appearance.

METHODS

Twenty fresh-frozen ankle specimens were used in this 4-phases study. First, the specimens were scanned on US to identify what was believed to be ATFL's superior fascicle. Second, ATFL's superior fascicle was sutured under direct arthroscopic vision. Next, the specimens were scanned on US to obtain an image of the sutured structure. Finally, the specimens were dissected to confirm that the suture was indeed placed on ATFL's superior fascicle.

RESULTS

On the 20 specimens studied, full correlation was obtained between US, arthroscopic suture and specimen dissection. ATFL's superior fascicle US appearance is provided.

CONCLUSION

ATFL's superior fascicle can be visualized on US, which will allow to undergo diagnosis of isolated injuries to that fascicle, a common finding in ankle microinstability. The results of this study will facilitate the diagnosis of partial or complete rupture of ATFL's superior fascicle, likely increasing the amount of ankle microinstability diagnosis, impacting clinical management of ankle sprain consequences.

Sonographic assessment of the tarsal tunnel compared to cadaveric findings: a pictorial study

Aim of the study

To present the anatomy of the tarsal tunnel and demonstrate the utility of high-resolution ultrasound for tarsal tunnel examination.

Materials and methods

Anatomical dissection was performed on a defrosted cadaveric model to demonstrate relevant anatomical structures of the tarsal tunnel, namely tendons, vessels and nerves. The tibial nerve division was demonstrated; the bifurcation of the tibial nerve into the medial and lateral plantar nerve, two medial calcaneal nerve branches were identified originating from the tibial nerve and the Baxter's nerve was identified as the first branch of the lateral plantar nerve. An ultrasound examination of the tarsal tunnel region was performed on a healthy volunteer. A linear probe was used and sonographic images were obtained at different levels of the tarsal tunnel: the proximal tarsal tunnel, the tibial nerve division into the medial and lateral plantar nerves, the distal tarsal tunnel, the Baxter's nerve branching point and the Baxter's nerve crossing between the abductor hallucis and quadratus plantae muscle.

Results

Sonographic images were correlated with anatomical structures exposed during cadaveric dissection.

Conclusions

We presented the anatomic-sonographic correlation of the tarsal tunnel and showed that high-resolution ultrasound is a useful imaging modality for tarsal tunnel assessment.

Ultrasound findings of the deltoid ligament in patients with acute ankle sprains: A retrospective review

BACKGROUND

The deltoid ligament is a complex structure composed of multiple ligaments located on the medial side of the ankle joint that can be injured by ankle sprains. Although there have been previous reports on ultrasound imaging of the injured deltoid ligament, a systematic method for depicting each ligament component has not been established. This study aimed to clarify the ultrasound findings of the deltoid ligament in ankle sprains using a systematic scanning protocol.

METHODS

We examined the tenderness of the medial ankle and evaluated the ultrasound findings of the deltoid ligament in 169 sprained ankles with no fracture, within 3 days after injury. Observation and evaluation of the six components of the deltoid ligament were performed using a systematic scanning protocol with four probe positions.

RESULTS

Of the 169 ankles, 48 ankles had tenderness in the deltoid ligament. Ultrasonography confirmed deltoid ligament damage in 13 of these 48 ankles. Of the 13 ankles, 3 ankles had damages only in the superficial layer, 3 ankles only in the deep layer, and 7 ankles in both the superficial and deep layers.

CONCLUSIONS

We clarified the details of the damage pattern of the deltoid ligament in acute ankle sprains. It was possible to identify the superficial and deep layers of the ligament and to observe the damage pattern of each ligament component in detail, and it appeared that ultrasonography could be used as a tool to evaluate the damage pattern of the deltoid ligament in acute ankle sprains.

Ultrasound Examination and Navigation for Repeat/Delayed Reconstruction of the Ankle Extensor Tendons

Herein, we describe a 46-year-old woman with persistent pain and weakness in her left ankle/foot one year after surgical repair of all three ankle extensor tendons following a penetrating injury. This report presents a unique case whereby US imaging played a paramount role in the diagnosis and surgical management of a previous nonanatomic repair of the ankle extensor tendons after a penetrating injury one year prior. The above-quoted findings were subsequently corrected with end-to-end sutures. On the third postoperative month follow-up, the patient was free of any complaints or complications.

A Technique Guide in Ultrasound Guided Regional Ankle Blocks

The use of ultrasound guided regional blocks is supported by the National Institute for Health and Care Excellence of the United Kingdom, for its safety and efficacy. This is a technique guide which is a culmination of the experiences gained in administering regional anesthesia under ultrasound guidance for ankle blocks as part of everyday podiatric surgery practice, based on a sound understanding of the principles of ultrasound science and instrumentation. It is in the opinion of the authors that the positioning of the patient is key, combined with an in-plane ultrasound guided technique, to perform a successful block of the selected nerve based on a foundation of knowledge and experience of anatomy and use of ultrasound respectively. This technique guide depicts annotated ultrasound images of the sonoanatomy to include the five nerves which innovate the foot that are required to be anesthetized for a selective or complete regional ankle block offering predictable peri-operative anesthesia, post-operative analgesia and early ambulatory discharge.

Novel, user-friendly landmarks for localizing Baxter's nerve: A cadaveric study

INTRODUCTION

Identification of Baxter's nerve (BN) has proven challenging for less experienced practitioners using ultrasonography due to a lack of adequate landmarks. This study aimed to establish novel, user-friendly anatomical landmarks and to describe useful structures to localize BN.

MATERIALS AND METHODS

We examined 10 fresh cadaveric feet and identified the interobserver agreement of measuring three surface landmarks: the most medially protruded point on the medial malleolus (P), the navicular tuberosity (Q), and the center of the calcaneus (B). Next, 24 fresh cadaveric feet were used to identify the point of BN entry into the quadratus plantae (QP) muscle, which corresponds to the proximal BN impingement site. The rectangular coordinate system consisted of the origin (point P), X-axis, extension line P-Q, and Y-axis (the perpendicular line to the X-axis). To consider various foot sizes, the X and Y values were divided by the P-Q length and were designated as the ratios X and Y.

RESULTS

Points P and Q showed smaller interobserver differences than that of point B. Ratios X and Y were 61.25 and 99.80%, respectively, for the QP. BN arose from the lateral plantar nerve in 20 of 24 specimens. The adjacent vessel was <3 mm from the entrapment site of BN in 20 of 24 specimens.

CONCLUSION

New landmarks will improve the precision of localizing the entrapment site of BN and will provide advanced guidelines for podiatric patients.

Artifacts in Musculoskeletal Ultrasonography: From Physics to Clinics

Ultrasound appears to be the most useful imaging tool in the diagnosis and guided treatment of musculoskeletal disorders. However, ultrasonography has been criticized for being user dependent. Therefore, medical professionals should be familiar with the basic principles of ultrasound imaging (e.g., physics and technical skills) to diminish artifacts and avoid misinterpretation. In this review, we focused on the physics of common artifacts, their clinical significance, and the ways to tackle them in daily practice during musculoskeletal imaging. In particular, artifacts pertaining to the focal zone, beam attenuation, path and side lobe of the beam, speed of the sound, and range ambiguity were described.

Artifacts in Musculoskeletal Ultrasonography: From Physics to Clinics

Ultrasound appears to be the most useful imaging tool in the diagnosis and guided treatment of musculoskeletal disorders. However, ultrasonography has been criticized for being user dependent. Therefore, medical professionals should be familiar with the basic principles of ultrasound imaging (e.g., physics and technical skills) to diminish artifacts and avoid misinterpretation. In this review, we focused on the physics of common artifacts, their clinical significance, and the ways to tackle them in daily practice during musculoskeletal imaging. In particular, artifacts pertaining to the focal zone, beam attenuation, path and side lobe of the beam, speed of the sound, and range ambiguity were described.

A Rare Case of Lateral Forefoot Pain: Plantar Adventitious Bursitis

Forefoot pain is a common musculoskeletal complaint but is rarely caused by plantar adventitious bursitis. A 27-year-old female had right lateral forefoot pain for three weeks and was referred for an ultrasound examination, revealing an anechoic mass on top of the flexor digiti minimi brevis tendon. Two weeks after oral medication and a prescription of rocker-bottom shoes, her pain totally disappeared. In conclusion, ultrasound is helpful in differentiating various causes of forefoot pain, which, in this case, facilitated the detection and management of plantar adventitious bursitis.

[Ultrasound of the Foot (Adapted According to SGUM Guidelines)]

Ultrasound of the Foot (Adapted According to SGUM Guidelines) Abstract. This review paper explains the simplified ultrasound anatomy of the foot including the ankle, midfoot and the toes. The adapted basic standard planes are described in detail according to SGUM guidelines and illustrated with a selection of high-resolution ultrasound images. A profound knowledge of the sonographic anatomy is essential for the detection of pathologies.