RADIOGRAPH- SKELETAL SYSTEM PATHOLOGY

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Acromegaly “large extremities” Hyperpituitarism. Abnormal enlargement of the terminal parts of the extremities, jaws, and nose owing to an excess of growth hormone. If pituitary malfunction leads to hypersecretion of GH during adulthood, the individual cannot grow taller. However, connective tissue thickness, and bones in the hands, feet and face may increase in diameter. Gigantism occurs during childhood when the anterior pituitary secretes too much GH and the individual may become abnormally tall.

Ankylosing Spondylitis AKA Marie-Strümpell disease, almost always begins in the sacroiliac joints, causing bilateral and usually symmetric involvement. Early radiographic changes demonstrate bilateral narrowing and fuzziness of the sacroiliac joints. Blurring of the articular margins and patchy sclerosis generally progress to narrowing of the joint space and may lead to complete fibrous and bony ankylosis. Eventually the sacroiliac joints become obliterated, and the condition progresses up the spine. Later radiographic changes show calcification of the bones of the spine with ossification of the vertebral ligaments. The articular cartilage is destroyed, and fibrous adhesions develop. These adhesions lead to bone fusion and calcification of the annulus fibrosis of the intervertebral disks as well as the anterior and lateral spinal ligaments. The spine becomes a rigid block of bone, giving the condition its characteristic nickname of “bamboo spine”.

Limitation of activity leads to generalized skeletal osteoporosis and a tendency to fracture in response to the stress of minor trauma. CT demonstrates the fusion as a result of the intraarticular and ligamentous ossification, and spinal stenosis caused by the displacement of fractures.

The disease primarily affects males under 30 years of age and generally follows a course of 20 years. There is a strong hereditary tendency as it is 20 times more common in the first-degree relatives of individuals known to have this disorder. In addition to the spine, the joints of the hip, shoulder, neck, ribs and jaw are often involved. When the costovertebral joints are involved, the patient may have difficulty in expanding the rib cage while breathing.

This is a systemic disease, often affecting the eyes and heart. Many patients also have inflammatory bowel disease. Most commonly, an individual will report low back pain varying in intensity, often nocturnal in nature and associated with morning stiffness. Other early signs and symptoms include a low-grade fever, fatigue, weight loss and anemia.

The aim of treatment is to reduce pain and inflammation in the involved joints, usually with non-steroidal anti-inflammatory drugs. Physical therapy helps keep the spine as erect as possible to prevent contractures. In advanced cases, surgery may be performed to straighten a badly deformed spine.

Bennett’s Fracture is an oblique fracture of the volar lip of the first metacarpal base and dislocation of the first carpometacarpal joint. This fracture results in an avulsion fracture at the base of the first metacarpal in association with a dislocation of the trapezium from the pulling action of the abductor tendon in the hand. The injury occurs when the thumb is forced backward while in partial flexion and is commonly seen in basketball players and skiers. It may be repaired with a closed pinning technique if the fracture displacement is less than 3mm or with an open reduction in cases of displacement greater than 3 mm.

Blow-out fracture is caused by a direct blow to the front of the orbit that causes a rapid increase in intraorbital pressure. The fracture occurs in the thinnest, weakest portion of the orbit, which is the orbital floor just above the maxillary sinus. Plain radiographs (modified Waters’ method), is the preferred screening study. CT may be necessary for better visualization and for detecting entrapment of the extraocular muscles in the upper portion of the adjacent maxillary sinus. The fracture segment can be comminuted, with a sagging, hammock-like appearance or can be of the trapdoor variety, with a displaced segment hanging into the antrum by a periosteal hinge. Herniation of the orbital fat and extraocular muscles into the fractured orbital floor  produces a charachteristic soft tissue shadow protruding through the floor into the superior portion of the maxillary sinus. Opacification of the sinus caused by hemorrhage and mucosal edema is an indirect sign of orbital floor fracture. The presence of air within the orbit (orbital emphysema) indicates that there is a communication with a paranasal sinus.

Bone dystrophies a general term used to describe any bone disorder due to defective or faulty nutrition. For example, Rickets=lack of vitamin D.

Chondroma A benign tumor or tumor like growth of cartilage cells. It may remain in the interior or substance of a cartilage or bone,(e.g. enchondroma), or may develop on a surface of a cartilage and project under the periosteum of a bone.

Compression Fracture results from a force that causes compaction of bone trabeculae and results in decreased length or width of a portion of a bone. Compression fractures most commonly occur in the thoracic, (T11-T12) and lumbar, (T12-L1),vertebral bodies particularly to the anterior margin;  as a result of flexion of the spine, they may also be seen as impacted fractures of the humeral or femoral heads.

Contrecoup fracture occurs on the side opposite of the trauma/blow. Frequently occurs in the mandibular ramus.

Cystic Bone Lesion is a true fluid-filled cyst with a wall of fibrous tissue, which most often occurs in the proximal humerus a=or femur at the metaphysis. Although not a true neoplasm, a simple bone cyst may resemble one radiographically and clinically. Solitary bone cysts are asymptomatic and often discovered either incidentally or after pathologic fracture. The simple bone cyst appears as an expansile lucent lesion that is sharply demarcated from adjacent normal bone and may have a thin rim of sclerosis around it. It has an oval configuration, with its long axis parallel to that of the host bone and may cause cortical bone thinning. MRI will determine if septations exist that may not be visible on the radiograph to aid in determining proper treatment.

Depressed fracture occurs in the skull or tibial plateau. In the skull, a small object with great force can produce a comminuted fracture, with portions of the fracture fragments driven inward. In the knee, the relatively hard lateral femoral condyle may impact on the relatively soft lateral tibial plateau with sufficient force to push the cortical surface of the tibia into the underlying cancellous bone.

Growth plate fractures (Salter-Harris) involve the end of a long bone of a child. The fracture may be limited to growth plate cartilage and thus not be directly visible unless displacement occurs, or it may extend into the metaphysis, epiphysis or both. Crush injuries of the growth plate can also occur. These growth plate fractures are classified according to severity and involvement of the epiphysis. This system is known as the Salter-Harris system: fractures are numbered I through V, with I being least severe and V being the most. Fracture that occur through the epiphysis are significant injuries because they can affect bone growth if not recognized and treated properly. Proper radiographic technique is required for the demonstration of both soft tissue and bone, This is especially important with type I fractures, in which the growth plate is separated as a result of a lateral blow, and type V fractures, in which the growth plate has sustained a compression injury. Types I and V fractures do not occur through the bone.

In the diagram below, the black lines represent the fracture lines.

A, A type 1 fracture occurs directly through the growth plate.

B, A type 2 fracture extends through the growth plate and into the metaphyses.

C, A type 3 fracture line extends through the growth plate and into the epiphyses.

D, A type 4 fracture line extends through the metaphyses, across or sometimes along the growth plate, and through the epiphyses.

E, A type 5 fracture involves a crushing of all or part of the growth plate.

Comparison projections are often used with such fractures to compare growth plate appearances, and MRI may be used to further evaluate epiphyseal separations. Healed injuries of this type may result in an alteration of the length of the involved bone. Because of possible length discrepancies, frequent radiographic examinations may be required, often up to years after the injury.

Hangman’s fracture is the result of acute hyperextension of the head on the neck. This appears as a fracture of the arch of C2 anterior to the inferior facet and is usually associated with anterior subluxation of C2 on C3. Although originally described in patients who had been hanged, this injury is now far more commonly the result of motor vehicle collisions.

Spiral fracture encircles the shaft, is generally longer than an oblique fracture, and is caused by torsional forces,\. Afracture in which the bone has been twisted apart, usually resulting from a rotary type of injury.

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