MR Imaging of the Plantar Plate

3D isotropic MRI of ankle: review of literature with comparison to 2D MRI

The ankle joint has complex anatomy with different tissue structures and is commonly involved in traumatic injuries. Magnetic resonance imaging (MRI) is the primary imaging modality used to assess the soft tissue structures around the ankle joint including the ligaments, tendons, and articular cartilage. Two-dimensional (2D) fast spin echo/turbo spin echo (FSE/TSE) sequences are routinely used for ankle joint imaging. While the 2D sequences provide a good signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) with high spatial resolution, there are some limitations to their use owing to the thick slices, interslice gaps leading to partial volume effects, limited fluid contrast, and the need to acquire separate images in different orthogonal planes. The 3D MR imaging can overcome these limitations and recent advances have led to technical improvements that enable its widespread clinical use in acceptable time periods. The volume imaging renders the advantage of reconstructing into thin continuous slices with isotropic voxels enabling multiplanar reconstructions that helps in visualizing complex anatomy of the structure of interest throughout their course with improved sharpness, definition of anatomic variants, and fluid conspicuity of lesions and injuries. Recent advances have also reduced the acquisition time of the 3D datasets making it more efficient than 2D sequences. This article reviews the recent technical developments in the domain 3D MRI, compares imaging with 3D versus 2D sequences, and demonstrates the use-case scenarios with interesting cases, and benefits of 3D MRI in evaluating various ankle joint components and their lesions.

SSR white paper: guidelines for utilization and performance of direct MR arthrography

OBJECTIVE

Direct magnetic resonance arthrography (dMRA) is often considered the most accurate imaging modality for the evaluation of intra-articular structures, but utilization and performance vary widely without consensus. The purpose of this white paper is to develop consensus recommendations on behalf of the Society of Skeletal Radiology (SSR) based on published literature and expert opinion.

MATERIALS AND METHODS

The Standards and Guidelines Committee of the SSR identified guidelines for utilization and performance of dMRA as an important topic for study and invited all SSR members with expertise and interest to volunteer for the white paper panel. This panel was tasked with determining an outline, reviewing the relevant literature, preparing a written document summarizing the issues and controversies, and providing recommendations.

RESULTS

Twelve SSR members with expertise in dMRA formed the ad hoc white paper authorship committee. The published literature on dMRA was reviewed and summarized, focusing on clinical indications, technical considerations, safety, imaging protocols, complications, controversies, and gaps in knowledge. Recommendations for the utilization and performance of dMRA in the shoulder, elbow, wrist, hip, knee, and ankle/foot regions were developed in group consensus.

CONCLUSION

Although direct MR arthrography has been previously used for a wide variety of clinical indications, the authorship panel recommends more selective application of this minimally invasive procedure. At present, direct MR arthrography remains an important procedure in the armamentarium of the musculoskeletal radiologist and is especially valuable when conventional MRI is indeterminant or results are discrepant with clinical evaluation.

Paediatric sand toe: radiographic, ultrasound and MRI findings of dorsomedial capsular injury

Hyperflexion injury to the metatarsophalangeal joint of the great toe, referred to as sand toe, can cause significant functional impairment. To our knowledge, there have been no radiological descriptions of this injury in the paediatric age group. Here, we report radiographic, sonographic and MRI findings in a male paediatric patient who sustained a sand toe injury, highlighting structural damage to the dorsomedial capsule and medial sagittal band, and discuss sand toe's favourable prognosis with conservative management.

Differential Diagnosis of Metatarsalgia

Lesser (or central) metatarsalgia is defined as pain in the forefoot under or around the lesser metatarsals and their respective metatarsophalangeal joints. Two common causes of central metatarsalgia are Morton's neuroma (MN) and plantar plate (PP) injury. Because both clinical and imaging features overlap, establishing the correct differential diagnosis may be challenging. Imaging has a pivotal role in the detection and characterization of metatarsalgia. Different radiologic modalities are available to assess the common causes of forefoot pain, so the strengths and weakness of these imaging tools should be kept in mind. It is crucial to be aware of the pitfalls that can be encountered in daily clinical practice when dealing with these disorders. This review describes two main causes of lesser metatarsalgia, MN and PP injury, and their differential diagnoses.

A Cadaveric Comparison of the Kinematic and Anatomical Axes and Arthrokinematics of the Metatarsosesamoidal and First Metatarsophalangeal Joints

Presently, developments in weightbearing computed tomography and biplanar fluoroscopy technologies offer exciting avenues for investigating normative and pathologic foot function with increasing precision. Still, data quantifying sesamoid bone and proximal phalange motion are currently sparse. To express joint kinematics and compare various clinical cohorts, future studies of first ray motion will necessitate robust coordinate frames that respect the variations in underlying anatomy while also aligning closely with the functional, physiological axes of motion. These activity-dependent functional axes may be represented by a mean helical axis of the joint motion. Our cadaveric study quantified joint kinematics from weightbearing computed tomography scans during simulated toe lift and heel rise tasks. We compared the spatial orientations of the mean finite helical axes of the metatarsosesamoidal and metatarsophalangeal joints to the primary joint axis of two relevant methods for defining metatarsal coordinate frames: inertial axes and fitting of geometric primitives. The resultant kinematics exhibited less crosstalk when using a metatarsal coordinate system based on fitting cylindrical primitives to the bony anatomy compared to using principal component axes. Respective metatarsophalangeal and metatarsosesamoidal arthrokinematic contact paths and instantaneous centers of rotation were similar between activities and agree well with currently published data. This study outlines a methodology for quantitatively assessing the efficacy and utility of various anatomical joint coordinate system definitions. Improvements in our ability to characterize the shape and motion of foot bones in the context of functional tasks will elucidate their biomechanical roles and aid clinicians in refining treatment strategies.

First Metatarsophalangeal Joint Pathology in the Athlete

Movement of the first metatarsophalangeal joint is an essential function of many sports. Because of the high demand on this relatively small joint, it is prone to the development of several notable pathologic derangements that can prevent full and pain-free athletic performance. A complete understanding of the joint anatomy and a careful physical examination and history collection is crucial to identifying an accurate diagnosis. Treatment should be pathology specific and should keep in mind the career expectations of the athlete.

Arthroscopic Repair of Chronic Plantar Plate Tears of the First Metatarsophalangeal Joint: A New Surgical Technique With Patient Outcomes

Background

Most plantar plate tears of the first metatarsophalangeal joint can be treated successfully by nonoperative means. Primary repair may be indicated to restore continuity of the plantar structures and joint stability. Inadequate or failed nonoperative treatment may cause persistent pain and disability and thereby represent a career-threatening injury to an athlete. The chronic plantar plate tears are difficult both to diagnose and to treat. When surgical treatment is indicated, traditionally a wide plantar or 2 parallel incisions are used. An arthroscopic approach allows for verification and visualization of the injury and, at the same time, repair of the injury.

Purpose

To describe findings of plantar plate tears, present a new arthroscopic procedure for plantar plate tear repair, and present the outcomes after surgery.

Study Design

Case series; Level of evidence, 4.

Methods

This was a retrospective study on the first 10 patients treated with the arthroscopic technique. The patients underwent surgery between June 2017 and January 2021. Patient data, clinical symptoms and findings, and operative details were obtained from the patient records. Patients were contacted via email to complete patient-reported outcome measures (Manchester Oxford Foot Questionnaire [MOxFQ] and Numeric Rating Scale [NRS] for pain).

Results

Four female and 6 male patients with a median age of 24 years (range, 12-44 years) were operated on at a median of 20 months (range, 2-38 months) after injury. Of the 10 patients, 8 had a hyperextension injury of the first metatarsophalangeal joint and 7 had a subtle valgus malalignment of the hallux; 8 patients were injured during sport activity. All patients reported plantar pain at pushoff. All but 1 patient returned to the same level of preinjury activity within 6 months. At a median of 29 months (range, 7-49 months) after surgery, the median MOxFQ score was 6 (range, 0-41) and the median NRS pain score was 0.

Conclusion

Arthroscopic plantar plate repair of chronic plantar plate tears resulted in a high rate of return to activity/sport and excellent outcome scores.

The Utility of Ultrasound in the Evaluation of Traumatic Hallux Valgus

Isolated disruption of the medial collateral ligament of the great toe is rare and often misdiagnosed as turf toe. It may progress to acquired traumatic hallux valgus, often requiring operative intervention and a longer return to play. This case of a grade II medial collateral ligament injury highlights the importance of a thorough physical examination and consideration of the mechanism of injury. It demonstrates the utility of diagnostic musculoskeletal ultrasound in establishing a specific diagnosis upon initial patient presentation with great toe pain. It is an example of the use of ultrasound in guiding treatment and monitoring interval healing. In this case, differentiation of the injury from the classic "turf toe" led to proper stabilization with a toe spacer and activity modification, thus preventing progression of traumatic hallux valgus and leading to successful nonoperative treatment with full return to sport.

LEVEL OF EVIDENCE

Level V.

Anatomy: Plantar Plate

The fibrocartilaginous component of the plantar plate offers stability at the metatarsophalangeal joint. In conjunction with the attachments of the deep transverse metatarsal ligaments and collateral ligaments, the plantar plate complex resists tensile forces anchored by the plantar fascia and compression forces under the metatarsal heads.

High-resolution 3T magnetic resonance imaging and histological analysis of capsuloligamentous complex of the first metatarsophalangeal joint

Background

There are discrepancies in the understanding of the structure of the capsuloligamentous complex of the first metatarsophalangeal joint (MTPJ); this study aims to investigate the differences with previous anatomical reports of high-resolution 3T magnetic resonance imaging (MRI) and histological analysis in illustrating the structure of the capsuloligamentous complex of the first MTPJ.

Methods

Nine fresh frozen cadaveric feet specimens (from two women and three men; aged 32 to 58 years) were used in this study. All specimens underwent MR examination with T1-weighted imaging and T2-weighted spectral attenuated inversion recovery in three planes. Subsequently, all cadaveric feet specimens were sliced into 2-mm-thick sections. The MRI features of the capsuloligamentous complex of the first MTPJ were analyzed in these specimens. Hematoxylin–eosin and Masson’s trichrome staining methods were used to explore the histologic features of the capsuloligamentous complex of the first MTPJ.

Results

Different from most previous studies, our results showed that the plantar plate could be divided into four portions including the central portion of the plantar plate, the intersesamoid, the sesamoid phalangeal and the metatarsosesamoid ligaments. The normal central portion of the plantar plate could be clearly visualized in the sagittal and coronal plane MR images. The intersesamoid ligament is a continuation of the central portion of the plantar plate on the sagittal plane on the gross specimen, the MR imaging, and the histological examination. On the coronal plane of the gross specimen and MR imaging, the sesamoid phalangeal ligaments and the central portion of the plantar plate can be seen as separate ligaments, but they appeared interwoven with the same continuous collagenous fibers on the histological analysis.

Conclusion

High-resolution 3T MRI allows accurate demonstration of the different anatomical details of the capsuloligamentous complex of the first MTPJ from previous anatomical reports. The histological analysis provides further understanding of the structures of the capsuloligamentous complex of the first MTPJ from previous studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02795-7.

Imaging of Turf Toe

Turf toe is a common injury of the hallux metatarsophalangeal (MTP) joint in athletes which is the result of hyperdorsiflexion injury. While the term turf toe has been used to describe a variety of first MTP joint injuries, the term is now typically used in imaging to describe tearing or injury to the plantar plate complex. This review article will cover normal anatomy of the first MTP joint, mechanism of injury, typical imaging findings in normal individuals on MRI and ultrasound, as well as the most common patterns of injury.

Dislocation of the first metatarsophalangeal joint concomitant with Lisfranc joint dislocation in a 45-year-old man

A 45-year-old man presented with severe pinch-point crush injury to his left foot. Plain radiographs revealed dislocation of the first metatarsophalangeal joint and dorsolateral dislocation of the basal phalanx and sesamoids. The first tarsometatarsal joint was subluxed in the plantar direction and the second to fourth tarsometatarsal joints were subluxed dorsally. The sesamoids were displaced dorsolateral to the metatarsal head. There was a longitudinal tear of the joint capsule at the medial margin of the medial sesamoid, which was sutured together with the abductor hallucis tendon and collateral ligament. The Lisfranc and dorsal ligaments in the tarsometatarsal joint were torn and repaired after reduction and fixed with a plate. One year after surgery, there was contracture of the first metatarsophalangeal joint, but the patient had no pain and was able to run.

Diagnosis and conservative management of great toe pathologies: a review

Acute great toe (Hallux) pain is a common complaint encountered by the primary care physician. Pathological conditions can vary from acute trauma to acute exacerbation of underlying chronic conditions. Delay in treatment or misdiagnosis can lead to debilitating loss of function and long-lasting pain. This review endeavors to discuss the pertinent history, physical exam findings, radiographic evidence, conservative treatment options, and surgical management for the musculoskeletal causes of acute and acute on chronic great toe pain in the adult population. The acute pathologies discussed in this review are hallux fractures and dislocations, turf toe, sand toe, and sesamoid disorders. The chronic pathologies discussed include hallux rigidus, hallux valgus, and chronic sesamoiditis.

Magnetic resonance imaging of the ankle and foot

This article reviews the magnetic resonance imaging (MRI) findings of the normal anatomy and various pathologic conditions of the ankle and foot commonly encountered in clinical practice. The spectrum of entities discussed includes osseous and osteochondral injuries, ligamentous injuries, common traumatic and degenerative tendon pathology, abnormalities of transverse tarsal joint (Chopart) and tarsometatarsal joint (Lisfranc) complexes, pathological conditions affecting capsuloligamentous structures of the great toe and lesser toes, as well as pedal infection, with a focus on diabetic osteomyelitis and neuropathic osteoarthropathy.

High-Resolution MRI of the First Metatarsophalangeal Joint: Gross Anatomy and Injury Characterization

The first metatarsophalangeal joint (MTPJ) is vital to the biomechanics of the foot and supports a weight up to eight times heavier than the body during athletic activities. The first MTPJ comprises osseous and cartilaginous surfaces along with a complex of supporting structures, including the dorsal extensor tendons, collateral ligaments, and a plantar plate complex. In contradistinction to the lesser MTPJ plantar plates, a single dominant fibrocartilaginous capsular thickening does not exist at the first MTPJ. Instead, the plantar plate complex comprises a fibrocartilaginous pad that invests the hallux sesamoids and is inseparable from the plantar capsule, the intersesamoid ligament, paired metatarsosesamoid and sesamoid phalangeal ligaments (SPLs), and the musculotendinous structures. Acute injury at the first MTPJ is typically secondary to forced hyperextension-turf toe-and can involve multiple structures. During hyperextension, the resulting forces primarily load the distal SPLs, making these structures more susceptible to injury. SPL injuries are best seen in the sagittal plane at MRI. Radiography can also aid in diagnosis of full-thickness SPL tears, demonstrating reduced sesamoid excursion at lateral dorsiflexed (stress) views. Hallux valgus is another common condition, resulting in progressive disabling deformity at the first MTPJ. Without appropriate treatment, first MTPJ injuries may progress to degenerative hallux rigidus. The authors detail the anatomy of the first MTPJ in cadaveric forefeet by using high-resolution 3-T and 11.7-T MRI and anatomic-pathologic correlation. Injuries to the plantar plate complex, collateral ligaments, and extensor mechanism are discussed using clinical case examples. Online supplemental material is available for this article. ^©RSNA, 2020.

Turf Toe Review

Turf toe is a term used to describe myriad injuries to the metatarsophalangeal complex of the great toe, which have been associated with the introduction of artificial turf surfaces in sport. If not diagnosed early and treated properly, these injuries can result in chronic pain and loss of mobility. Accurate injury grading through physical exam and advanced imaging is essential to guide treatment, thereby minimizing long-term complications and maximizing an athlete's recovery and return to play. Levels of Evidence: Level V.

Relationship Between Demographic and Radiographic Characteristics and Second Ray Pathology in Hallux Valgus Patients

BACKGROUND

Hallux valgus can alter load bearing in the foot leading to abnormal forces on the second toe. The purpose of this study was to determine demographic and radiographic factors associated with second ray hammertoes in hallux valgus using 3-dimensional weightbearing CT scans.

METHODS

Seventy-one patients who underwent a modified Lapidus procedure for hallux valgus with preoperative weightbearing CT scans were separated into 2 groups: (1) hallux valgus only (47 feet) and (2) hallux valgus with second ray hammertoe (29 feet). Preoperative age, body mass index (BMI), sex, hallux valgus angle (HVA), intermetatarsal angle (IMA), absolute and effective metatarsal (MT) lengths, ratios between metatarsal lengths, Meary angle, metatarsus adductus angle (MAA), and pronation were measured. Mean values of continuous variables were compared and both simple and multivariable logistic regression models were used to evaluate associations between variables and hammertoe occurrence.

RESULTS

Patients in the hammertoe group were found to be significantly older and have higher BMIs, HVAs, effective second MT lengths, IMAs, and more apex plantar Meary angles (all P < .05). The multivariable analysis demonstrated that a higher IMA and a more apex plantar Meary angle were the only significant predictors of second ray hammertoe risk (P = .03 and P = .01, respectively) once corrected for age and BMI.

CONCLUSION

Significant associations were found between older age, higher BMI, and more severe deformity and the occurrence of hammertoe in hallux valgus patients. These results may help clinicians counsel hallux valgus patients about the risk of developing an advanced hammertoe deformity.

LEVEL OF EVIDENCE

Level III, retrospective comparative series.

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.

Imaging in Foot and Ankle Instability

This article reviews the imaging aspects relevant to ligamentous instabilities of the foot and ankle with a focus on MRI and ultrasound imaging. A pictorial review of the anatomy of the medial and lateral ankle ligaments, syndesmosis, spring ligament, Lisfranc complex, hallux sesamoid complex, and lesser toe plantar plate as seen on MRI is presented. Selected cases of ligamentous pathology relevant to foot and ankle instability are presented. The value of imaging in the assessment of foot and ankle instability is reviewed.

Anatomy and Physiology of the Lesser Metatarsophalangeal Joints

Knowledge and command of anatomy is paramount to effectively treating disorders of the lesser metatarsophalangeal (MTP) joints. The osseous structures consist of the proximal phalanx of the toe and the metatarsal head. The soft tissues on the dorsum of the MTP joint include the joint capsule and the tendons of extensor digitorum longus and extensor digitorum brevis. The proper and accessory collateral ligaments form the medial and lateral walls and contribute to stability in the coronal and sagittal planes. The plantar plate forms the plantar border of the MTP joint and stabilizes the MTP joint against hyperextension and dorsal translation.