Online Quiz

CASE 1: (Closed)

History :
50 / M Presented with pain in the Right Lower Limb. H / O Physical Exercise and walking for past 10 days.

Question:

Review the imaging series and give your diagnosis.
What are the differentials diagnosis?

Please see the answer below.

ANSWER

FINDINGS:








  • A, B & C MR images showing periosteitis and edema in relation to endosteal & periosteal aspect of medial cortical bone.
  • The (A) STIR Coronal image demonstrates a vertically - oriented lucent line, bordered by dark sclerotic lines (Yellow Arrow). Additional images (not shown) confirmed this to correspond in position to the abnormality found on the axial image and not a nutrient vessel. There is no osseous or soft tissue mass.
  • The (B) STIR sagittal image demonstrates a vertically elongated area of linear cortical abnormality (Yellow Arrow) spanning several centimeters in length. Edema is seen in a large portion of the tibial marrow, but is most prominent adjacent to the posterior cortical abnormality.
  • The (C) STIR axial image shows marrow edema(Orange Arrow) and periosteal edema (Yellow Star)involving the mid tibia, most prominent posteriorly.
  • The posterior tibial cortex is discretely disrupted as a linear cleft, with elevated cortical ridges along the cleft.
  • The (D) axial CT image demonstrates a fracture line (Yellow Arrow) with callus formation (Orange dotted Arrow).
  • The (E, F) sagittal, coronal reconstructed CT image demonstrates a longitudinal fracture line (Orange Arrow).

DIAGNOSIS:Longitudinal Tibial Stress Fracture:

Teaching Points

  • Marrow edema visible on MRI can have multiple aetiologies, and may raise concerns of malignancy or osteomyelitis, particularly when a periosteal reaction is present. Other causes of marrow edema include stress reaction, trauma, or secondary changes from adjacent inflammatory arthritis or tenosynovitis. In young patients, red marrow may also mimic or mask marrow edema. The finding of marrow edema should prompt a search for a more specific underlying abnormality. A longitudinal stress fracture of the tibia is a challenging but recognizable diagnosis on MR, and is likely significantly more common than has been previously reported. Patients with longitudinal stress fractures may present with an atypical clinical history, and thus recognition of the characteristic MR appearance of these lesions is critical in making the correct diagnosis.

DISCUSSION /GENERAL CONSIDERATIONS:

  • Stress fractures are common injuries that begin with repetitive and excessive stress on the bone. This leads to the acceleration of normal bone remodelling, the production of microfractures (caused by insufficient time for the bone to repair), the creation of a bone stress injury (i.e., stress reaction to activities like Running, walking, jumping, dancing, female athlete), and, eventually, a stress fracture. In contrast, pathological (insufficiency) fractures occur under normal stress in bone weakened by a tumour, infection, or osteoporosis.
  • The most common locations for stress fracturesare the tibia (more than 50%), tarsal navicular, metatarsal, fibula, femur, pelvis, and spine (in descending order of occurrence)
  • Stress fractures are not difficult to diagnose if the symptoms and signs are understood and if it is remembered that there is a varying-but usually lengthy-delay before there is radiological confirmation of the fracture. Such fractures, in long bones, are commonly transverse or oblique.
  • Tibial stress fracture account for over 50% of all stress fracture and are particularly common in military practice and athletes. Individual with tibial stress fracture present with shin pain which is often associated with a recent acceleration in their level of lower extremity exercise. Majority of tibial stress fracture are transverse in orientation with longitudinal orientation in only 10% of cases. Unlike the much more common transverse tibial stress fracture, longitudinal stress fractures usually occurs in middle aged and elderly adults and are not typically exercise related. Medial tibial stress syndrome also known as "shin splints" is an early stage in the continuum that culminates in a stress fracture. The relative role of compressive versus torsional forces in the development of MTSS and ultimately stress fractures have been debated. Recent work appears to favour the latter. Compressive forces account for transverse often subchondral, stress fractures in proximal tibia. Torsional forces may be of greater significance in the tibial shaft and may account for higher number of longitudinal fractures.

CLINICAL FEATURES:

  • Stress fracture should be suspected in persons with a drastic recent increase in physical activity or repeated excessive activity with limited rest. Pain is a common presenting symptom. Specifically, pain with ambulation is common (81 %). On examination, patients usually demonstrate focal tenderness (65.9 to 100 %) and edema (18 to 44 %) at the site of injury

IMAGING FINDINGS:

  • Clues to the MRI diagnosis of longitudinal fracture of the tibial shaft include edema distribution along the endosteum and periosteum of one cortex, most often posteriorly or anteromedially. The axial images are frequently diagnostic, demonstrating a linear lucency on multiple sequential images, and often endosteal and periosteal callus formation. The sagittal or coronal sequences are helpful in demonstrating the length of involvement and the site of greatest edema, which indicates the most likely fracture site. A fracture line is occasionally visible on the coronal or sagittal sequences, depending on fortuitous positioning of the image slice relative to the affected cortex.
  • An imaging pitfall in the diagnosis of stress fractures is that of a normal nutrient foramen. Nutrient foramina course obliquely through the tibial cortex, and exhibit a round shape on axial images, progressing from the inner to the outer cortical surfaces. An associated vessel can typically be seen extending beyond the foramen, within the marrow space as well as external to the bone.
  • MRI is well suited for distinguishing between stress fractures and pathologic fractures. Well-demarcated T1 signal abnormality, endosteal scalloping, and an adjacent soft tissue mass are each indicators of neoplasm rather than stress fracture.
  • MRI grading for tibial stress reaction consists of five grades: grade 0 indicates normal MRI findings. Grade 1 indicated increased signal involving the periosteal region as seen on T2-weighted images only, with normal marrow signal intensity on all images. Grade 2 added bone marrow signal changes on T2-weighted images. Grade 3 added the presence of bone marrow signal changes on T1-weighted images, and grade added the presence of a clearly visible fracture line

TREATMENT:

  • Depending on the injury, healing time for stress fractures can vary from four to 12 weeks or longer from the time activity is restricted. Initial treatment should include reducing activity to the level of pain-free functioning. Patients may require limited or full nonweight-bearing crutches to reduce pain.
  • Treatment should begin as soon as the injury is suspected, because delayed treatment has been correlated with prolonged return to activity.The patient can be examined every two to three weeks to ensure pain-free functioning, monitor changes in symptoms, and evaluate improvement in provocative testing. When patients are pain free, they may increase activity in a slow, graduated manner.
  • Analgesics, such as acetaminophen and nonsteroidal anti-inflammatory drugs, may be considered for pain control.

DIFFERENTIAL DIAGNOSIS:

  • Medial tibial stress syndrome /shin splints.
  • Osteoid osteoma (eccentric, nidus, solid periosteal reaction, night pain).
  • Chronic sclerosing osteomyelitis─ Brodie's abscess ─ (dense, sclerotic, involving entire circumference, little change on serial radiographs)
  • Medial tibial stress syndrome /shin splints: Medial tibial stress syndrome (shin splints) can be distinguished from tibial stress fractures by nonfocal tenderness (diffuse along the mid-distal, posteromedial tibia) and a lack of edema; no abnormalities will appear on radiography).
  • Osteoid osteoma occurs in the young, usually between the ages of 10 and 35, and its sites of predilection are the long bones, particularly the femur and tibia osteoid osteoma occurs in the young, usually between the ages of 10 and 35, and its sites of predilection are the long bones, particularly the femur and tibia. It is a benign osteoblastic lesion characterized by a nidus of osteoid tissue, which may be purely radiolucent or have a sclerotic center. The nidus has limited growth potential and usually measures less than 1 cm in diameter. It is often surrounded by a zone of reactive bone formation.
  • Brodie abscess issub acute localized form of osteomyelitis, commonly caused by staphylococcus aureus. The highest incidence (approximately 40%) is in the second decade. its onset is often insidious, and systemic manifestations are generally mild or absent. The abscess, which is usually localized in the metaphysis of the tibia or femur, is typically elongated, with a well-demarcated margin and surrounded by reactive sclerosis. As a rule, sequestra are absent, but a radiolucent tract may be seen extending from the lesion into the growth plate.

RARE DIFFERENTIALS:

  • Malignancies such as osteosarcoma and Ewing sarcoma.

REFERENCES:

  1. Orthopedic Imaging: A Practical Approach, 4th Edition. Editors : Greenspan , Adam
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