MR IMAGING IN SPORTS INJURIES OF THE FOOT AND ANKLE

Multiaxial 3D MRI of the Ankle: Advanced High-Resolution Visualization of Ligaments, Tendons, and Articular Cartilage

MRI is a valuable tool for diagnosing a broad spectrum of acute and chronic ankle disorders, including ligament tears, tendinopathy, and osteochondral lesions. Traditional two-dimensional (2D) MRI provides a high image signal and contrast of anatomic structures for accurately characterizing articular cartilage, bone marrow, synovium, ligaments, tendons, and nerves. However, 2D MRI limitations are thick slices and fixed slice orientations. In clinical practice, 2D MRI is limited to 2 to 3 mm slice thickness, which can cause blurred contours of oblique structures due to volume averaging effects within the image slice. In addition, image plane orientations are fixated and cannot be changed after the scan, resulting in 2D MRI lacking multiplanar and multiaxial reformation abilities for individualized image plane orientations along oblique and curved anatomic structures, such as ankle ligaments and tendons. In contrast, three-dimensional (3D) MRI is a newer, clinically available MRI technique capable of acquiring high-resolution ankle MRI data sets with isotropic voxel size. The inherently high spatial resolution of 3D MRI permits up to five times thinner (0.5 mm) image slices. In addition, 3D MRI can be acquired image voxel with the same edge length in all three space dimensions (isotropism), permitting unrestricted multiplanar and multiaxial image reformation and postprocessing after the MRI scan. Clinical 3D MRI of the ankle with 0.5 to 0.7 mm isotropic voxel size resolves the smallest anatomic ankle structures and abnormalities of ligament and tendon fibers, osteochondral lesions, and nerves. After acquiring the images, operators can align image planes individually along any anatomic structure of interest, such as ligaments and tendons segments. In addition, curved multiplanar image reformations can unfold the entire course of multiaxially curved structures, such as perimalleolar tendons, into one image plane. We recommend adding 3D MRI pulse sequences to traditional 2D MRI protocols to visualize small and curved ankle structures to better advantage. This article provides an overview of the clinical application of 3D MRI of the ankle, compares diagnostic performances of 2D and 3D MRI for diagnosing ankle abnormalities, and illustrates clinical 3D ankle MRI applications.

MRI in Acute Ankle Sprains: Should We Be More Aggressive with Indications?

Acute ankle sprains are common sports injuries. MRI is the most accurate test for assessing the integrity and severity of ligament injuries in acute ankle sprains. However, MRI may not detect syndesmotic and hindfoot instability, and many ankle sprains are treated conservatively, questioning the value of MRI. In our practice, MRI adds value in confirming the absence or presence of ankle sprain-associated hindfoot and midfoot injuries, especially when clinical examinations are challenging, radiographs are inconclusive, and subtle instability is suspected. This article reviews and illustrates the MRI appearances of the spectrum of ankle sprains and associated hindfoot and midfoot injuries.

Imaging of Acute Ankle and Foot Sprains

Ankle and foot injuries are very common injuries in the general population, and more so in athletes. MR imaging is the optimal modality to evaluate for ligamentous injuries of the ankle and associated conditions after ankle sprain. In this article, the authors discuss the epidemiology, biomechanics, normal anatomy, and pathology of the ankle as well as injuries of the hindfoot and midfoot that are often associated with ankle injuries.

Plantar fasciitis in physicians and nurses: a nationwide population-based study

Physicians and nurses in Taiwan have heavy workload and long working hours, which may contribute to plantar fasciitis. However, this issue is unclear, and therefore, we conducted this study to delineate it. We conducted a nationwide population-based study by identifying 26,024 physicians and 127,455 nurses and an identical number of subjects for comparison (general population) via the National Health Insurance Research Database. The risk of plantar fasciitis between 2006 and 2012 was compared between physicians and general population, between nurses and general population, and between physicians and nurses. We also compared the risk of plantar fasciitis among physician subgroups. Physicians and nurses had a period prevalence of plantar fasciitis of 8.14% and 13.11% during the 7-yr period, respectively. The risk of plantar fasciitis was lower among physicians (odds ratio [OR]: 0.660; 95% confidence interval [CI]: 0.622-0.699) but higher among nurses (OR: 1.035; 95% CI: 1.011-1.059) compared with that in the general population. Nurses also had a higher risk than the physicians after adjusting for age and sex (adjusted odds ratio [AOR]: 1.541; 95% CI: 1.399-1.701). Physician subspecialties of orthopedics and physical medicine and rehabilitation showed a higher risk. Female physicians had a higher risk of plantar fasciitis than male physicians. This study showed that nurses, physician specialties of orthopedics and physical medicine and rehabilitation, and female physicians had a higher risk of plantar fasciitis. Improvement of the occupational environment and health promotion are suggested for these populations.

Plantar tendons of the foot: MR imaging and US

Tendon disorders along the plantar aspect of the foot may lead to significant symptoms but are often clinically misdiagnosed. Familiarity with the normal anatomy of the plantar tendons and its appearance at magnetic resonance (MR) imaging and ultrasonography (US) is essential for recognizing plantar tendon disorders. At MR imaging, the course of the plantar tendons is optimally visualized with dedicated imaging of the midfoot and forefoot. This imaging should include short-axis images obtained perpendicular to the long axis of the metatarsal shafts, which allows true cross-sectional evaluation of the plantar tendons. Normal plantar tendons appear as low-signal-intensity structures with all MR sequences. At US, accurate evaluation of the tendons requires that the ultrasound beam be perpendicular to the tendon. The normal tendon appears as a compact linear band of echogenic tissue that contains a fine, mixed hypoechoic and hyperechoic internal fibrillar pattern. Tendon injuries can be grouped into six major categories: tendinosis, peritendinosis, tenosynovitis, entrapment, rupture, and instability (subluxation or dislocation) and can be well assessed with both MR imaging and US. The radiologist plays an important role in the diagnosis of plantar tendon disorders, and recognizing their imaging appearances at MR imaging and US is essential.

The diagnosis and treatment of heel pain: a clinical practice guideline-revision 2010

Heel pain, whether plantar or posterior, is predominantly a mechanical pathology although an array of diverse pathologies including neurologic, arthritic, traumatic, neoplastic, infectious, or vascular etiologies must be considered. This clinical practice guideline (CPG) is a revision of the original 2001 document developed by the American College of Foot and Ankle Surgeons (ACFAS) heel pain committee.

The incidence of plantar fasciitis in the United States military

BACKGROUND

Although plantar fasciitis is the most common cause of heel pain, little has been reported on the incidence rates of this disorder. We sought to determine the incidence rate and demographic risk factors of plantar fasciitis in an ethnically diverse and physically active population of United States military service members.

METHODS

A query was performed with use of the Defense Medical Epidemiology Database for the International Classification of Diseases, Ninth Revision, Clinical Modification, code for plantar fasciitis (728.71). Multivariate Poisson regression analysis was used to estimate the rate of plantar fasciitis per 1000 person-years, while controlling for sex, race, rank, service, and age.

RESULTS

The overall unadjusted incidence rate of plantar fasciitis was 10.5 per 1000 person-years. Compared with men, women had a significantly increased adjusted incidence rate ratio for plantar fasciitis of 1.96 (95% confidence interval, 1.94 to 1.99). The adjusted incidence rate ratio for black service members compared with white service members was 1.12 (95% confidence interval, 1.09 to 1.12). With junior officers as the referent category, junior enlisted, senior enlisted, and senior officer rank groups had a significantly increased adjusted incidence rate ratio for plantar fasciitis: 1.20 (95% confidence interval, 1.18 to 1.23), 1.19 (95% confidence interval, 1.17 to 1.22), and 1.56 (95% confidence interval, 1.52 to 1.61), respectively. Compared with service members in the Air Force, those in the Army and Marines had a significantly increased adjusted incidence rate ratio for plantar fasciitis of 1.85 (95% confidence interval, 1.82 to 1.87) and 1.28 (95% confidence interval, 1.25 to 1.30), respectively. The adjusted incidence rate ratio for the age group of forty years old or more compared with the twenty to twenty-four-year-old group was 3.42 (95% confidence interval, 3.34 to 3.51).

CONCLUSIONS

Female sex; black race; junior enlisted, senior enlisted, and senior officer rank groups; service in the Army or Marines; and increasing age are all risk factors for plantar fasciitis.

Osteochondral injuries of the foot and ankle

Osteochondral injuries commonly affect the ankle joint and involve the dome of the talus. This article describes the etiology and pathogenesis of these injuries. Their clinical presentation is described and advice is given on how to diagnose and investigate suspected osteochondral injuries. The various treatment options currently available are briefly reviewed. There is some attempt made to give consensus on optimal treatment of this condition at the present time.

MR arthrography of the ankle: indications and technique

MR arthrography has become an important tool for the assessment of a variety of ankle disorders. MR arthrography permits more sensitive imaging of suspected intra-articular pathology in cases in which conventional MR imaging is either insufficient or inadequate for diagnosis or treatment planning. The main indications for MR arthrography are the evaluation of ligamentous injuries, impingement syndromes, cartilage lesions, osteochondral lesions of the talus, loose bodies, and several synovial joint disorders. Indirect MR arthrography can be a useful adjunct to conventional MR imaging and may be preferable to direct MR arthrography in those cases in which an invasive procedure is contraindicated or image guidance is not available.

Bone stress injuries of the ankle and foot: an 86-month magnetic resonance imaging-based study of physically active young adults

BACKGROUND

No comprehensive studies of bone stress injuries in the ankle and foot based on magnetic resonance imaging findings have been published.

PURPOSE

Using magnetic resonance imaging findings to assess incidence, location, and type of bone stress injuries of the ankle and foot in military conscripts with ankle and/or foot pain.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

All patients with ankle or foot pain, negative findings on plain radiography, and magnetic resonance images obtained of the ankle or foot were included in this 86-month study. Magnetic resonance images with bone stress injury findings were re-evaluated regarding location and injury type. Based on the number of conscripts within the hospital catchment area, the person-based incidence of bone stress injuries was calculated.

RESULTS

One hundred thirty-one conscripts displayed 378 bone stress injuries in 142 ankles and feet imaged, the incidence being 126 per 100 000 person-years. This incidence represents the stress injuries not diagnosable with radiographs and requiring magnetic resonance images. Of injuries, 57.7% occurred in the tarsal and 35.7% in the metatarsal bones. Multiple bone stress injuries in 1 foot were found in 63% of the cases. The calcaneus and fifth metatarsal bone were usually affected alone. Injuries to the other bones of the foot were usually associated with at least 1 other stress injury. The talus and calcaneus were the most commonly affected single bones. High-grade bone stress injury (grade IV-V) with a fracture line on magnetic resonance images occurred in 12% (talus, calcaneus), and low-grade injury (grade I-III) presented only as edema in 88% of the cases.

CONCLUSION

Multiple, various-stage bone stress injuries of the ankle and foot may occur simultaneously in physically active young adults. When considering injuries that were missed by plain radiographs but detected by magnetic resonance imaging, the bones most often affected were the tarsal bones, of which the talus and calcaneus were the most prominent single bones and most common locations for higher grade (IV-V) bone stress injuries. With use of magnetic resonance imaging, early detection and grading of bone stress injuries are available, which enable early and appropriate injury management.

Ankle MR Arthrography: How, Why, When

MR arthrography has become an important tool for the assessment of a variety of ankle disorders. MR arthrography may facilitate the evaluation of patients with suspected intra-articular pathology in whom conventional MR imaging is not sufficient for an adequate diagnosis and be useful for therapy planning. MR arthrography is valuable in the evaluation of ligamentous injuries, impingement syndromes, cartilage lesions, osteochondral lesions of the talus, loose bodies, and several synovial joint disorders. Indirect MR arthrography is a useful adjunct to conventional MR imaging and may be preferable to direct MR arthrography in cases in which an invasive procedure is contraindicated or when fluoroscopy is not available.

Imaging the ankle and foot and using magnetic resonance imaging

Magnetic resonance (MR) imaging has improved the possibility of evaluating musculoskeletal structures thus gaining an important role in the diagnosis and treatment of foot and ankle pathologies. In this review, the normal and pathological images of the ankle and foot obtained using MR techniques are presented and discussed. The high soft-tissue contrast resolution and the multiplanar sections of MRI allow the imaging of contiguous tissues where small contrast differences exist, such as ligamentous and tendinous injuries or impingement syndromes. The spatial resolution with high sensitivity for bone signal changes offers an early detection of osseous abnormalities such as stress fractures or osteonecrosis. Here it is specified possibilities and limitations of MRI in the diabetic foot: this technique is superior to nuclear medicine and computed tomography (CT), however it is unable to distinguish between neuro arthropathy and infection.

Pictorial review: MRI features of foot and ankle injuries in ballet dancers

Foot and ankle pain is common in ballet dancers. Although clinical examination often points to the underlying cause, imaging is often necessary to confirm the diagnosis and thus ensure appropriate future management. Factors predisposing to the increased incidence of injuries in this population include the classical position in which ballet dancers stand, which is on the tips of the toes in the en pointe position or on the balls of the feet in the demi-pointe position. Furthermore, the repetitious nature of ballet and the long hours spent rehearsing cause over-use injuries. The causes of foot and ankle pain can be thought of in four different groups: the impingement syndromes; tendon abnormalities; osseous pathology; and ligament abnormalities. These will be discussed and illustrated.

Magnetic resonance imaging of the hip: sports-related injuries

Normal hip disorders do not account for a large proportion of exercise-related injuries, but they can pose a clinical dilemma because symptoms tend to be nonspecific. Conventional radiographs may demonstrate some causes of hip pain, such as stress fractures and degenerative joint disease. Magnetic resonance imaging (MRI) of the hip has proven valuable in the diagnosis of radiographically occult osseous abnormalities and periarticular soft-tissue disorders such as stress fractures, avulsion injuries, musculotendinous abnormalities, and bursitis. Conventional MRI has been less useful in the evaluation of intra-articular lesions, including acetabular labral tears, intra-articular loose bodies, and cartilage lesions. Visualization of intra-articular structures and their abnormalities can be improved by injection of diluted gadolinium, which distends the capsule and leaks into labral tears. This article focuses on the use of conventional radiography and MRI in recreational and professional athletes with painful hip joints. Where possible, MRI is compared with other diagnostic modalities such as bone scan and computed tomography.

Overuse and sports-related injuries of the ankle and hind foot: MR imaging findings

Professional and recreational sporting activities have increased substantially in recent years and have led to a rise in the number of sports-related and overuse injuries. Magnetic resonance (MR) imaging has become an important tool for evaluating the lower leg for providing the necessary information for patient management and rehabilitation following this injury. The purpose of this essay is to give an overview of the MR findings of common overuse injuries and sports-related injuries to the bones and soft-tissue structures of the hind foot and ankle.

Imaging of athletic injuries to the ankle and foot

Conventional radiographs in conjunction with clinical examination remains the primary method for evaluating the acute athletic injury. In most cases, suspected acute tendon and ligament injuries are initially treated based on physical examination. Magnetic resonance (MR) imaging, with its multiplanar capability and superb soft tissue contrast, is quickly becoming the method of choice for evaluating chronic foot and ankle pain and further defining the extent of tendon and ligament injuries. This article reviews the common acute and chronic (overuse) foot and ankle athletic injuries with an emphasis on imaging characteristics.

Imaging of hip disorders in athletes

Normal hip joint function is fundamental in running-, jumping-, and kicking-based sporting activities. Hip disorders do not account for a large portion of exercise-related injuries, but they can pose a clinical dilemma since symptoms tend to be non-specific. Conventional radiographs may demonstrate some causes of hip pain, such as stress fractures and degenerative joint disease. Magnetic resonance (MR) imaging of the hip has proven valuable in the diagnosis of radiographically occult osseous abnormalities and periarticular soft tissue disorders such as stress fractures, avulsion injuries, musculotendinous abnormalities, and bursitis. Conventional MR imaging has been less useful in the evaluation of intra-articular lesions including acetabular labral tears, intra-articular loose bodies, and cartilage lesions. The visualization of intra-articular structures and their abnormalities can be improved by the injection of diluted Gadolinium, which distends the capsule and leaks into labral tears. This article will focus on the use of conventional radiography and MR imaging in recreational and professional athletes with painful hip joints, and where possible it will compare MR imaging with other diagnostic modalities such as bone scan and CT.

Heel pad thickness--a contributing factor associated with plantar heel pain in young adults

Thirty-three runners were clinically diagnosed with plantar heel pain (PHP) and 107 runners were designated into a non-PHP group (NPHP). Cases were matched with a further control group of 64 subjects with regard to body mass index and age. A weight-bearing platform measured heel pad thickness by real-time ultrasound scanning. The results demonstrated a significant difference between the PHP and both the NPHP and control groups (P <0.05). The results also demonstrated that body mass index had a significant effect (P <0.05) on the heel pad thickness of all subjects, regardless of the heel pad group. The results from the current study, with some precaution, conclude that body mass index as such is not related to PHP in the athletic population. In the current study the observed differences of body mass index on heel pad thickness between the PHP and NPHP groups, and the similarity between the control group and NPHP subjects suggests other risk factors may play an important role in heel pad thickening and associated development of PHP.

Forefoot pain involving the metatarsal region: differential diagnosis with MR imaging

Many disorders produce discomfort in the metatarsal region of the forefoot. These disorders include traumatic lesions of the soft tissues and bones (eg, turf toe, plantar plate disruption, sesamoiditis, stress fracture, stress response), Freiberg infraction, infection, arthritis, tendon disorders (eg, tendinosis, tenosynovitis, tendon rupture), nonneoplastic soft-tissue masses (eg, ganglia, bursitis, granuloma, Morton neuroma), and, less frequently, soft-tissue and bone neoplasms. Prior to the advent of magnetic resonance (MR) imaging, many of these disorders were not diagnosed noninvasively, and radiologic involvement in the evaluation of affected patients was limited. However, MR imaging has proved useful in detecting the numerous soft-tissue and early bone and joint processes that occur in this portion of the foot but are not depicted or as well characterized with other imaging modalities. Frequently, MR imaging allows a specific diagnosis based on the location, signal intensity characteristics, and morphologic features of the abnormality. Consequently, MR imaging is increasingly being used to evaluate patients with forefoot complaints. Radiologists should be familiar with the differential diagnosis and MR imaging features of disorders that can produce discomfort in this region.

Tenology: a new frontier

Tendons were long given little recognition by rheumatologists. Yet, their complex structure and distinctive functional characteristics have been demonstrated by an abundance of histological, biochemical, and biomechanical studies: clearly, tendons are not inert cords linking muscles to bones. The current wave of popularity of sporting activities has brought with it an epidemic of disorders of the tendons, thus focusing attention on these structures. At the same time, modern imaging techniques (particularly magnetic resonance imaging) have allowed clinicians to improve their knowledge of and classification schemes fortendon disorders. Several risk factors, including technical factors, have been identified, so that preventive treatment is now as important as curative treatment. Culture systems for tenocytes (the specialized fibroblasts found in tendons) are now available and have been used to develop experimental models, paving the way for significant advances in tendon repair techniques.

From the RSNA Refresher Courses. Radiological Society of North America. MR imaging of the ankle and foot

Magnetic resonance (MR) imaging has opened new horizons in the diagnosis and treatment of many musculoskeletal diseases of the ankle and foot. It demonstrates abnormalities in the bones and soft tissues before they become evident at other imaging modalities. The exquisite soft-tissue contrast resolution, noninvasive nature, and multiplanar capabilities of MR imaging make it especially valuable for the detection and assessment of a variety of soft-tissue disorders of the ligaments (eg, sprain), tendons (tendinosis, peritendinosis, tenosynovitis, entrapment, rupture, dislocation), and other soft-tissue structures (eg, anterolateral impingement syndrome, sinus tarsi syndrome, compressive neuropathies [eg, tarsal tunnel syndrome, Morton neuroma], synovial disorders). MR imaging has also been shown to be highly sensitive in the detection and staging of a number of musculoskeletal infections including cellulitis, soft-tissue abscesses, and osteomyelitis. In addition, MR imaging is excellent for the early detection and assessment of a number of osseous abnormalities such as bone contusions, stress and insufficiency fractures, osteochondral fractures, osteonecrosis, and transient bone marrow edema. MR imaging is increasingly being recognized as the modality of choice for assessment of pathologic conditions of the ankle and foot.

Painful heel: MR imaging findings

Heel pain is a common and frequently disabling clinical complaint that may be caused by a broad spectrum of osseous or soft-tissue disorders. These disorders are classified on the basis of anatomic origin and predominant location of heel pain to foster a better understanding of this complaint. The disorders include plantar fascial lesions (fasciitis, rupture, fibromatosis, xanthoma), tendinous lesions (tendinitis, tenosynovitis), osseous lesions (fractures, bone bruises, osteomyelitis, tumors), bursal lesions (retrocalcaneal bursitis, retroachilleal bursitis), tarsal tunnel syndrome, and heel plantar fat pad abnormalities. With its superior soft-tissue contrast resolution and multiplanar capability, magnetic resonance (MR) imaging can help determine the cause of heel pain and help assess the extent and severity of the disease in ambiguous or clinically equivocal cases. Careful analysis of MR imaging findings and correlation of these findings with patient history and findings at physical examination can suggest a specific diagnosis in most cases. The majority of patients with heel pain can be successfully treated conservatively, but in cases requiring surgery (eg, plantar fascia rupture in competitive athletes, deeply infiltrating plantar fibromatosis, masses causing tarsal tunnel syndrome), MR imaging is especially useful in planning surgical treatment by showing the exact location and extent of the lesion.