SPECIAL TYPES OF TRAUMA

A stress fracture refers to a fracture occurring in bone due to a mismatch of bone strength and chronic mechanical stress placed upon the bone.

1.STRESS FRACTURE

It can either be: fatigue fracture - abnormal stresses on normal

bone

insufficiency fracture - normal stresses on abnormal bone

LOCATION

March fracture Mid and distal tibia Proximal fibula

RADIOLOGICAL FEATURES

Plain filmOsteal bone

endosteal or periosteal callus formation without fracture line

circumferential periosteal reaction with fracture line through one cortex

frank fracture

Cancellous bone flake-like patches of new bone formation (2-3 weeks) cloudlike area of mineralized bone focal linear area of sclerosis, perpendicular to the

trabeculae

A 42-year old female who walks long distances and has been experiencing forefoot pain for a month. On the initial radiograph no fracture is seen.After 4 weeks, a follow up radiograph clearly marks callus formation at the site of the stress fracture.

MRI

has surpassed bone scintigraphy as the imaging tool for stress fractures

sensitivity (100%) specificity (85%)

Grading is based on signs seen at MRI:1. mild - moderate periosteal edema on STIR, no

marrow changes 2. moderate - severe periosteal edema on STIR +

marrow changes on T2WI3. + marrow changes on T1WI4. fracture line visible

A 22-year old female, a professional athlete with a recent onset of forefoot pain, persisting after training. At presentation MRI showed a high signal on the STIR- and a low signal on T1WI (i.e. grade 3 stress fracture).

A 27-year old soccer player in the highest league of amateur football. He suffered from midfoot pain with a recent increase in complaints. T1WI shows a definite fracture line in the navicular bone, indicating a grade 4 stress fracture.Corresponding CT shows a fracture line and sclerosis on the axial images and coronal reconstructions.

2.SPONDYLOLISTHESIS

forward displacement of a vertebra anterolisthesis relative to the segment below, typically due to spondylolysis (pars interarticularis defects).

Most frequent at L5/S1 and to a lesser degree L4/5 articularis defects). 

grade I: 0-25% grade II: 25-50%  grade III: 50-75%  grade IV: 75-100%   spondyloptosis: >100% 

3.AVULSION FRACTURE

result when the fracture fragment is pulled from its parent bone by forceful contraction of a tendon or ligament

Young adults(M:F= 2:1) In the pelvis, the newly formed secondary centers

of ossification, the apophysis, are the most likely portions of the bone to avulse

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IMAGING FINDINGS

Conventional radiography is the study of first choice

avulsed bony fragment usually immediately adjacent to the parent bone

SITES OF AVULSION FX WITH MUSCLE ORIGIN

Site of avulsion fracture Muscle origin

Anterior superior iliac spine Sartorius

Anterior inferior iliac spine Rectus femoris

Ischial tuberosity Hamstrings

Greater trochanter Gluteals

Posterior calcaneus Achelles tendon

Olecranon process Triceps

Superior patella Quadriceps

Inferior patella Patella ligament

Tibial tuberosity Patella ligament

OSGOOD-SCHLATTER DISEASE Lateral view x-ray of the knee

demonstrating fragmentation of the tibial tubercle with overlying soft tissue swelling.

SINDIG-LARSEN DISEASE

4.PATHOLOGICAL FRACTURE

A fracture that occurs through bone which was previously abnormal• metastatic lesion • multiple myeloma• enchondroma• unicameral bone cysts

IMAGING FINDINGS

Fracture line extending through a destructive lesion in the boneUsually transverse in direction

Surrounding bone may demonstrateEndosteal scallopingCortical destruction

Frequently associated with a soft tissue mass

DRILLER’S DISEASE(VIBRATION SYNDROME)

Workers using vibration machinery >5 years of use Degenerative cysts found in the bones of wrist

Avascular Necrosis of the Scaphoid. Frontal view of the wrist shows increased density and partial collapse of the proximal pole of the scaphoid (blue arrow) secondary to a fracture of the waist of the scaphoid (red arrow).The smooth and sclerotic margins of the fracture line suggest non-union of the fracture and there is increaseddistance between the scaphoid and the lunate suggesting disruption of the scapholunate ligaments. . 

Frontal view of the hand and wrist demonstrates sclerosis, irregularity and collapse of the lunate (blue arrows) in Kienbock's Disease

Frieberg’s disease

5.MYOSITIS OSSIFICANS

a benign process characterized by heterotopic ossification usually within large muscles.

Trauma Paraplegia(hip and knee joint ) Ligamentous avulsion or chronic ligamentous

trauma

Plain film Calcification (2-6 weeks) well circumscribed peripherally calcified

appearance(2 months). Cleft between it an the subjacent bone may be

difficult to see on plain films(string sign)

CT

Mineralization proceeding from the outer margins towards the centre.String signThe peripheral rim of mineralization (4-6week)

MRI

Early changes:.T1

ill-defined isointense to muscle massT2

periphery: high signal (oedema) seen up to 8 weeks central: heterogeneous

T1 C+ (Gd): enhancement is often present

Late appearances mimic bone T1

periphery: low signal (mature lamellar bone) central: intermediate to high signal (bone marrow)

T2 periphery: low signal (mature lamellar bone) central: intermediate to high signal (bone marrow)

T1 C+ (Gd): usually none in mature lesions.

Pellegrini-Stieda lesions are ossified post-traumatic lesions at (or near) the medial femoral collateral ligament adjacent to the margin of the medial femoral condyle. One presumed mechanism of injury is a Stieda fracture (avulsion injury of the medial collateral ligament at the medial femoral condyle).

DD’S

Parosteal osteosarcoma: calcifies in centre and continues towards the peripheryMalignant fibrous histiocytomaSynovial sarcoma

6.COMPARTMENT SYNDROME

Limb-threatening and life-threatening condition observed when perfusion pressure falls below tissue pressure in a closed anatomic space. 

Compartment syndrome progresses to rhabdomyolysis if untreated

Fasciotomy

T1W-images of a patient one month post trauma. On the post-Gadolinium image the necrosis in the anterior and lateral compartment is seen. The posterior compartment is normal.

T2W-image of a patient with a chronic lateral compartment syndrome.

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