Postoperative MRI of the Ankle and Foot.

Many surgical procedures and operations are used to treat ankle and foot disorders. Radiography is the first-line imaging for postoperative surveillance and evaluation of pain and dysfunction. Computed tomography scans and MR imaging are used for further evaluation. MR imaging is the most accurate test for soft tissues assessments. MR imaging protocol adjustments include basic and advanced metal artifact reduction. We chose a surgical approach to select the common types of procedures and discuss the normal and abnormal postoperative MR imaging appearances, highlighting potential complications. This article reviews commonly used surgical techniques and their normal and abnormal MR imaging appearances.

Metatarsalgia.

Although causes of metatarsalgia are multifactorial, in practice these most commonly include osseous stress reaction or fracture (including subchondral injury) and interdigital neuroma or plantar plate tear with adjacent pseudoneuroma. The various roles of radiography, ultrasonography, and MR imaging are discussed, and relevant technical issues and imaging findings are reviewed in order to facilitate accurate diagnosis and guide proper treatment of metatarsalgia.

Not One of the Usual Suspects: MRI Features of Insertional Lateral Cord Plantar Fasciopathy.

OBJECTIVE: The purpose of this article is to report MRI findings of insertional lateral cord plantar fasciopathy and review the presenting symptoms of the condition and suspected diagnoses. CONCLUSION: Lateral cord plantar fasciopathy presents with pain and swelling at the lateral midfoot, which are typically clinically suspected to be caused by fifth metatarsal (MT) base stress fracture of peroneal tendon abnormalities. The MRI findings are identical to those seen in association with the more commonly occurring central cord plantar fasciopathy, which has a calcaneal origin, but the findings affect the insertion of the lateral cord onto the plantar lateral base of the fifth MT.

MR Imaging of the Plantar Plate: Normal Anatomy, Turf Toe, and Other Injuries.

The metatarsophalangeal (MTP) joint complex is a weight-bearing structure important to the biomechanics of the standing position, walking, shoe wearing, and sport participation. Acute dorsiflexion injury of the first MTP joint, "turf toe," is common among American football and soccer players. The first and lesser MTP joint complexes can be affected by degenerative or inflammatory arthritis, infarct, and infection. These conditions can lead to plantar plate disruption. Imaging studies help physicians to properly diagnose and treat this condition. This article reviews the anatomy, diagnostic imaging, and clinical management of injury and pathology of the first and lesser MTP joint complexes.

Etiology, Clinical Assessment, and Surgical Repair of Plantar Plate Tears.

The plantar plate has recently gained more attention as an important structure contributing to lesser metatarsophalangeal joint stability. This has prompted a significant growth of interest in the anatomy and biomechanics of the plantar plate and in the diagnosis and treatment of its injuries. Improved understanding of plantar plate function and predictable patterns of degeneration and failure has led to the development of a clinical staging and surgical grading system of plantar plate lesions. Relatively recent innovations allow the surgeon to access and repair plantar plate tears directly with reinsertion onto the base of the proximal phalanx. The addition of direct plantar plate repair represents a significant advance in the surgical restoration of alignment and functional stability of the lesser metatarsophalangeal joint.

Predictive MRI correlates of lesser metatarsophalangeal joint plantar plate tear.

PURPOSE: To identify correlated signs on non-enhanced MRI that might improve diagnostic detection of plantar plate (PP) tear. MATERIALS AND METHODS: We performed an IRB-approved, HIPAA-compliant retrospective analysis of 100 non-contrast MRI (50 PP tear, 50 controls). All were anonymized, randomized, and reviewed; 20 were duplicated to assess consistency. One musculoskeletal radiologist evaluated qualitative variables. A trained non-physician performed measurements. Consistency and concordance were assessed. Pearson's Chi-square test was used to test the correlation between qualitative findings and PP tear status. Correlation between measurements and PP status was assessed using t tests and Wilcoxon's rank-sum test (p values < 0.05 considered significant). Classification and regression trees were utilized to identify attributes that, taken together, would consistently distinguish PP tear from controls. RESULTS: Quantitative measurements were highly reproducible (concordance 0.88-0.99). Elevated 2nd MT protrusion, lesser MT supination and rotational divergence of >45° between the 1st-2nd MT axis correlated with PP tear. Pericapsular soft tissue thickening correlated most strongly with PP tear, correctly classifying 95 % of cases and controls. Excluding pericapsular soft tissue thickening, sequential assessment of 2nd toe enthesitis, 2nd flexor tendon subluxation, and splaying of the second and third toes accurately classified PP status in 92 %. CONCLUSIONS: Pericapsular soft tissue thickening most strongly correlated with PP tear. For cases in which it might be difficult to distinguish pericapsular fibrosis from neuroma, sequential assessment of 2nd toe enthesitis, flexor tendon subluxation and splaying of the 2nd and 3rd toe is most helpful for optimizing accurate diagnosis of PP tear.

MRI of lesser metatarsophalangeal joint plantar plate tears and associated adjacent interspace lesions.

OBJECTIVE: To identify the variety of second and third intermetatarsal space (IS) lesions that may coexist with and without adjacent metatarsophalangeal joint (MTP) plantar plate (PP) tears. MATERIALS AND METHODS: One hundred forefoot MRIs in 96 patients with metatarsalgia obtained between 30 September 2011 and 21 July 2012 using 1.5- or 3-T MRI were retrospectively reviewed in consensus by two MSK radiologists and one podiatrist (DPM). MRI was evaluated for second and third MTP PP tear and the presence/nature of second and third IS lesions. Second and third IS neuromas were measured in transverse (trans) dimension. RESULTS: A total of 40 PP tears were identified: 36 at the second and 4 at the third MTP. Second MTP PP tear was identified in 33% of females and 40.5% of males. In the 63 female feet there were 21 second MTP PP tears, all of which also had second IS lesions: pericapsular fibrosis (16), bursitis (4), and ganglion (1). In the 37 male feet there were 15 second MTP PP tears, 14 of which had second IS lesions: pericapsular fibrosis (8), bursitis (5), and ganglion (1). There was no definite second IS neuroma adjacent to any second MTP PP tear. In females without PP tear, there were 24 second (3 mm trans average) and 43 third IS neuromas (4.1 mm trans average). In males without PP tear, there were 9 second (3.4 mm trans average) and 16 third IS neuromas (4.1 mm trans average). CONCLUSIONS: MTP PP tears occurred in 40% of our cases, 90% of which occurred at the second MTP. Almost all coexisted with non-neuromatous second IS lesions.

Sea urchin spine arthritis in the foot.

We present a case of sea urchin spine arthritis (SUSA) in a 33-year-old woman who sustained penetrating trauma to the interphalangeal (IP) joint of the hallux while snorkeling in Japan. Serial radiographs and MRI were obtained over a period from 7 weeks to 10 months following injury. At 7 weeks radiographs revealed periarticular osteopenia and subtle marginal erosion, similar to the appearance of tuberculous arthritis. Over the ensuing months, radiographs and MRI documented progressive marginal and periarticular erosions with synovitis, despite preservation of cartilage space and restoration of bone mineral density. Delayed radiographs and imaging features mimic gouty arthropathy. Only the history points to the proper diagnosis, which was confirmed by histopathology, demonstrating necrobiotic granuloma with central fibrinoid necrosis following synovectomy and arthrodesis. The majority of previous case reports affected the hand, with few cases in the feet. In all, radiographic illustrations were limited and demonstrated only minimal osteolysis and periosteal reaction. No other report included MRI or serial radiographs over a long period to illustrate the natural progression of the disease.

Sonographic assessment of suture artifact obscuring visualization of the digital nerve.

INTRODUCTION: The purpose of this study was to grade the severity of sonographic artifact produced by four suture materials and to determine whether these artifacts affect visualization of a digital nerve. METHODS: A needle was placed into a pig foot to mimic a normal volar digital nerve. Incisions superficial to the needle were closed with different suture types, specifically nylon (N), chromic (C), vicryl (V), and prolene (P). Sonographic images were obtained using a high-frequency transducer. Twenty radiology residents and attending physicians graded the severity of artifact and nerve obscuration. Two image types were shown: one suture type per image and a composite image of each suture type, adjacent to one another. RESULTS: Severity of nerve obscuration was as follows: composite image: P = N = V > C; individual images: P > N > V > C. Severity of artifact was: composite image: V = N > P > C; individual image: P > N > V > C. CONCLUSION: Although all sutures produced artifact, only C produced mild artifact, which did not significantly obscure visualization of the nerve model.

Proximal iliotibial band syndrome: what is it and where is it?

OBJECTIVE: To describe the clinical and MR imaging features of a unique strain at the iliac tubercle enthesis. While this strain appeared to correspond to the iliotibial band (IT band) enthesis, the literature regarding the IT band origin was discrepant. As such, our second goal was to prove that the IT band originated at the iliac tubercle, through cadaveric dissection. MATERIALS AND METHODS: Three musculoskeletal radiologists prospectively reviewed 67 consecutive bony pelvis MRI studies from October 2006 through September 2008 using either 3, 1.5, or 0.3 T units. Seven cases demonstrating strain at the iliac tubercle enthesis were identified and reviewed by consensus. History and patient demographics were reviewed. Cadaveric dissection was performed to delineate the anatomy of the proximal IT band. RESULTS: Seven out of 67 individuals, all women, were identified with strain at the level of the iliac tubercle (prevalence 10%). Four of seven were athletes, three were overweight. Patients presented with pain and tenderness at the iliac tubercle. Anatomic dissection confirmed that iliotibial band originates along the margin of the iliac crest with dominant fibers condensing on the iliac tubercle. CONCLUSION: Proximal IT band strain represents a unique injury that should be considered in patients who are female athletes or older overweight women who present with pain and tenderness at the iliac tubercle. Imaging of this entity must include the iliac tubercle, which is often excluded in standard hip MRI.

MRI of broken bioabsorbable crosspin fixation in hamstring graft reconstruction of the anterior cruciate ligament.

PURPOSE: To report seven cases of broken bioabsorbable femoral crosspins identified by MRI in evaluation of hamstring grafts of the anterior cruciate ligament. METHODS: Seven cases of broken bioabsorbable crosspins utilized in femoral fixation of ACL hamstring grafts were identified prospectively and retrospectively from our PACs database during a period from 9/1/08 to 8/31/09. All imaging was performed using 1.5 or 3.0 Tesla MRI and were evaluated for T2 signal within and surrounding the crosspin, osteolysis surrounding the fragments, displacement of fragments, and graft integrity. Time from surgery was also recorded. RESULTS: Seven cases of hamstring grafts with broken bioabsorbable crosspins were imaged 4 months to 3 years following grafting. There was osteolysis surrounding the crosspin in all but one case in which the graft was intact but a pin fragment was displaced into the joint. One graft failed due to aseptic foreign-body reaction to the fixation with aggressive osteolysis at 9 months post surgery. In the remaining five, the ACL graft was either completely torn, partially torn, lax, or degenerative and frayed. Of these, the crosspins were broken and angulated with osteolysis surrounding the apex of the angulated fragment or demonstrated lateral extrusion of the peripheral fragment. CONCLUSIONS: Bioabsorbable crosspins utilized in femoral fixation of hamstring graft reconstruction of the ACL may become fractured. While the natural history of osteo-integration of these devices as demonstrated by MRI has not been defined, osteolysis surrounding the fragments, extrusion or displacement of the fragments, and graft laxity or failure would suggest that these are abnormal findings that should be reported.

Sonographic assessment of volar digital nerve injury in the context of penetrating trauma.

OBJECTIVE: The purpose of this article was to report our experience using ultrasound to assess digital nerve integrity after penetrating hand trauma with sensory deficit. Ultrasound was performed in the long axis on 22 digital nerves in 11 patients using a 12-14-MHz linear array hockey stick transducer. CONCLUSION: Of 22 volar digital nerves evaluated by sonography, six were transected. All imaging findings were confirmed surgically. High-frequency ultrasound permits accurate imaging of intact and transected volar digital nerves.

Meniscal root tears: diagnosis and treatment.

Meniscal tears within the body of the meniscus or at the meniscocapsular junction represent a well-understood and manageable condition encountered in clinical practice. In comparison, however, meniscal root tears (MRTs) often go unnoticed and represent a unique injury pattern with unique biomechanical consequences. Though first described decades ago, improvements in magnetic resonance imaging and arthroscopy have only recently enhanced our diagnostic and treatment capabilities with regard to MRTs. This review contains an anatomic description of the roots including their significance in meniscal function as well as the consequences of their loss. In addition, how to properly identify MRTs and when it is appropriate to surgically repair them are described. Finally, we review the surgical techniques available in the existing literature and present an illustrative case.

Anterior ankle impingement syndromes.

Ankle impingement syndromes are painful conditions that may complicate ankle trauma and are characterized by chronic, progressive pain, swelling, and limitation of movement. These disorders are subclassified according to anatomical location about the tibiotalar joint. This article reviews the various forms of anterior ankle impingement, detailing the unique clinical features, anatomical considerations, pathoetiology, and imaging findings for each.

Marginal fractures of the medial tibial plateau: possible association with medial meniscal root tear.

We report two cases of marginal fractures of the medial tibial plateau associated with medial meniscal root tears. Both patients sustained knee dislocations, with complete tears of the posterior horn medial meniscal root. One sustained a "reverse Segond fracture"; the other sustained an "anteromedial impingement fracture" of the tibial plateau. The meniscal root tears were arthroscopically confirmed and repaired. In the first patient, the integrity of the meniscal root repair was confirmed at a 6-month follow-up arthroscopy for lysis of adhesions. In the second patient, follow-up MRI at 10 months demonstrated a healed meniscal root. The association of medial meniscal root tear with marginal fractures of the medial tibial plateau has not been previously reported.

Comparison of CT and MRI in patients with tibial plateau fracture: can CT findings predict ligament tear or meniscal injury?

OBJECTIVE: (1) To determine the accuracy of computed tomography (CT) in the evaluation of ligament tear and avulsion in patients with tibial plateau fracture. (2) To evaluate whether the presence or severity of fracture gap and articular depression can predict meniscal injury. DESIGN AND PATIENTS: A fellowship-trained musculoskeletal radiologist retrospectively reviewed knee CT and MRI examinations of 41 consecutive patients presenting to a level 1 trauma center with tibial plateau fractures. Fracture gap, articular depression, ligament tear and footprint avulsions were assessed on CT examinations. The MRI studies were examined for osseous and soft tissue injuries, including meniscal tear, meniscal displacement, ligament tear, and ligament avulsion. RESULTS: CT demonstrated torn ligaments with 80% sensitivity and 98% specificity. Only 2% of ligaments deemed intact on careful CT evaluation had partial or complete tears on MRI. Although the degree of fracture gap and articular depression was significantly greater in patients with meniscal injury compared with those without meniscal injury, ROC analysis demonstrated no clear threshold for gap or depression that yielded a combination of high sensitivity and specificity. CONCLUSIONS: In the acute setting, CT offers high sensitivity and specificity for depicting osseous avulsions, as well as high negative predictive value for excluding ligament injury. However, MRI remains necessary for the preoperative detection of meniscal injury.