Skeletal System PDF

CHAPTER 2 Skeletal System 1. Butterfly Vertebra 14. Avascular Necrosis 2. Cervical Rib 15. Spondylosis 3. Osgood-Schlatter’s Disease 16. Spondylolisthesis 4. Osteogenesis Imperfecta...

CHAPTER 2 Skeletal System 1. Butterfly Vertebra 14. Avascular Necrosis 2. Cervical Rib 15. Spondylosis 3. Osgood-Schlatter’s Disease 16. Spondylolisthesis 4. Osteogenesis Imperfecta 17. Osteopoikilosis 5. Osteopetrosis 18. Bone Cysts 6. Osteoporosis 19. Bone Tumors 7. Osteomalacia 20. Enchondroma 8. Osteomyelitis 21. Osteochondroma 9. Rheumatoid Arthritis 22. Multiple Myeloma 10. Ankylosing Spondylitis 23. Osteosarcoma 11. Gout 24. Chondrosarcoma 12. Osteoarthritis 25. Fibrosarcoma 13. Paget’s Disease 26. Secondary Bone Cancer Butterfly Vertebra:  A butterfly vertebra is a congenital defect of a vertebra that produces the radiographic appearance of a butterfly on an AP projection.  Most are of no significance but they do have the potential for causing instability or altering the shape of the spinal canal. Cervical Rib:  This is a supernumerary or extra rib that is attached to C7.  It is a poorly developed or rudimentary rib that is present in approximately 0.05% of the population.  It is usually unilateral but in some cases, they can be bilateral.  The concern with a cervical rib is that it may compress the brachial nerve plexus or the subclavian artery and thus require surgical removal. Osgood-Schlatter Disease:  This disease is one of the most common causes of knee pain in young athletes.  Osgood-Schlatter disease mainly affects boys ages 10 to 16.  It is a condition where the tibial tuberosity becomes inflamed following exercise.  Treatment primarily consists of rest. Osteogenesis Imperfecta (OI):  This is a relatively rare congenital bone disorder that is characterized by bones that easily break.  This condition is sometimes referred to as “brittle bone” disease.  People with this OI are born with insufficient amounts of a protein called type I collagen which plays an important role in bone formation.  This collagen deficiency will result in osteopenia which is a decrease in the number of osteocytes.  In severe cases, multiple fractures can form while the fetus is in the womb. As a result, many infants are stillborn or die shortly after birth. Osteopetrosis:  This disorder results from a disorder of endochondral ossification and is the opposite of osteoporosis.  Patients with this very rare condition possess bones that are very hard and dense. As a result, osteopetrosis is sometimes referred to as “marble bone” disease. Oddly enough, their bones tend to be more brittle than normal.  It can be fatal at birth or asymptomatic into adulthood.  There is currently no definitive treatment for osteopetrosis.  This disease is characterized by a reduction in bone mass that makes patients with this condition susceptible to fracture formation. The underlying mechanism in all cases is an imbalance between the body’s normal process of bone destruction followed by bone growth.  There are many factors involved in the pathogenesis of osteoporosis. The primary causes are aging and postmenopausal hormone changes. Other causes include steroid use, osteogenesis imperfecta, multiple myeloma, and inactivity.  Patients with this condition are prone to hip fractures, compression fractures of the vertebral bodies, and Colles’ fractures of the wrist.  A common method to diagnose this condition is by the use of a dual energy X-ray absorptiometry (DEXA) scan. A DEXA scan provides a non invasive means to measure bone mineral density (BMD). Osteomalacia:  This disease is characterized by a softening of bones that results from insufficient mineralization.  Osteomalacia may cause a “bowing” of bones or lead to greenstick fractures.  It can be caused by a decrease in absorption of either vitamin D or calcium.  It can also be manifested in children who ingest an insufficient amount of vitamin D or who are not exposed to enough sunlight  This is commonly called rickets. Osteomyelitis:  This condition is the result of a bacterial bone infection that causes bone destruction and abscess formation. One characteristic is the formation of a Brodie’s abscess. It is typically found in the tibia and is an indication of osteomyelitis.  Another characteristic of osteomyelitis is a sequestrum formation. This is an avascular “island” of bone that forms within an abscess. It is commonly referred to as a bone-in-bone formation.  Osteomyelitis can be acute or chronic. It is usually treated with prolonged antibiotic therapy. Rheumatoid Arthritis (RA):  This type of arthritis can involve joints, muscles, tendons, ligaments, and blood vessels.  It begins as a chronic inflammation of synovial membranes that line joints.  Thickened tissue (pannus) forms as a result of the inflammation and this causes erosion of the articular cartilage.  Fibrous scaring occurs followed by ankylosis or “freezing” of the affected joint.  The net result is a crippling deformity which begins in the extremities and progresses toward the trunk.  RA can relapse but may still have intermittent flair ups.  This disease affects women three times more often than men.  Signs and symptoms of RA include morning stiffness, pain, and ulnar deviation of the fingers.  Treatment includes steroids to reduce the inflammation and analgesics (aspirin) for pain. Ankylosing Spondylitis:  This is a chronic, degenerative arthritis that usually begins in the sacroiliac (SI) joints and spreads to the spine.  It is characterized by osteoporosis and fusion of the SI joints and vertebral bodies.  Due to its very distinctive radiographic appearance, it is commonly referred to as “bamboo spine” disease.  Treatment includes steroids to reduce the inflammation and analgesics (aspirin) for pain. Gout:  Gout, or metabolic arthritis, is a disorder of purine metabolism that results in an increase in uric acid production.  The excess uric acid is deposited in the blood, kidneys, and joints.  Joint deposits form as crystals that cause a very painful inflammatory reaction.  Gout is primarily manifested in the feet (great toe) but it can also affect other areas such as the hands and knees. Osteoarthritis:  This is the most common degenerative joint disease.  Osteoarthritis is characterized by a natural loss of joint cartilage that is related to but not caused by aging.  The body replaces this loss of cartilage with the formation of new bone in the form of spurs.  These bone spurs cause the painful inflammation that is associated with this condition.  Osteoarthritis can affect most joints in the body including the hands, wrists, hips, and spine.  Signs and symptoms include joint stiffness and pain that increases with activity.  It is also affected by the weather and obesity.  Treatment includes steroids to reduce the inflammation, analgesics (aspirin) for pain, and joint replacement surgery (total hip replacements). Paget’s Disease:  Paget’s disease is also known as osteitis deformans.  It is characterized by an abnormal cycle or process of bone destruction followed by excessive bone growth and thickening.  Paget’s disease is commonly seen in the pelvis, lumbar spine, and skull.  Signs and symptoms include bone pain, deformity, arthritis, and fractures. Avascular Necrosis (AVN):  AVN is characterized by bone ischemia followed by bone inflammation and necrosis.  It can occur with navicular fractures but is most commonly seen in the femoral head, knee, and shoulder.  AVN of the femoral head is often treated with a total hip replacement.  Some causes of AVN include excessive steroid use, trauma, and alcoholism.  MRI is the imaging modality of choice in the diagnosis of AVN. Spondylosis:  This condition is characterized by a cleft between the superior and inferior articulating processes at the pars interarticularis.  It is usually bilateral and the net result is a loss of the neural arch continuity.  It is commonly found 90% of the time between L5 and S1. Spondylolisthesis:  This condition is secondary to spondylosis.  Spondylolisthesis is characterized by the forward movement (subluxation) of one vertebral body on the one below it.  This causes the vertebral canal to narrow and thus impinge on the nerve roots. It has four grades (I, II, III, IV).  It is possible for a patient to have spondylosis without having spondylolisthesis.  Treatment includes back support/braces and surgery. Osteopoikilosis:  Osteopoikilosis is an osteosclerotic bone dysplasia that is literally translated as “spotted bones.”  It produces many small radiopaque densities that are sometimes referred to as bone islands.  It has an unknown etiology and is usually asymptomatic.Osteopoikilosis: Bone Cysts:  Bone cysts are common, benign, expansile, radiolucent lesions that are filled with fluid.  They are more prevalent in males than females and have an unknown etiology.  Depending on their location, they may cause pain or even a pathologic fracture. Otherwise, they have no significance. Bone Tumors:  There are two general categories of bone tumors: 1. Osteolytic They result in a decrease in bone density and have a lucent radiographic appearance. 2. Osteoblastic They result in an increase in bone density and have an opaque radiographic appearance.Bone Tumors: Enchondroma:  This is a cartilaginous, benign bone lesion that is found in bone marrow.  It is most commonly found in young adults.  Enchondromas are most often located in the bones of the hands, feet, and ribs.  They present with a radiolucent, “cystic” appearance with calcium deposits. Osteochondroma:  An osteochondroma or exostosis consists of a benign projection of bone that has a cartilaginous cap.  They are generally found in the metaphysis of long bones, the ribs, and the pelvis.  Osteochondromas often produce a mushroom or cauliflower radiographic appearance and are sometimes referred to as a bone spur. Multiple Myeloma:  This is the most common type of primary, malignant bone tumor.  It is characterized by an increase in plasma cells within RBC producing bones. Plasma cells are immune system cells that are found in the bone marrow and produce antibodies.  The cardinal signs of multiple myeloma are as follows: 1. Possess “multicentric” or “punched-out” osteolytic lesions. 2. Bence-Jones proteins are found in the urine. 3. Possess marked osteoporosis with compression fractures of the vertebral bodies.  Since there is no curative treatment for multiple myeloma, treatment is focused on suppression and containment.  Remission can be induced with the use chemotherapy, stem cell treatment, and steroids.Multiple Myeloma: Osteosarcoma:  Osteosarcoma is the second most common type of malignant bone tumor.  This is an osteoblastic lesion that may extend into the surrounding soft tissue structures.  It is primarily found in ages 10 to 25 and 50% of all cases occur around the knee.  Osteosarcomas commonly metastasize to the lungs and they have a very poor prognosis. Chondrosarcoma:  A chondrosarcoma is an expansile, osteolytic, primary bone tumor.  They represent approximately 10% of all malignant skeletal cancers. Fibrosarcoma:  A fibrosarcoma is an osteolytic, malignant cancer of the skeletal system that often has a moth-eaten radiographic appearance.  It is a primary cancer of the skeletal system and it often affects the knee and pelvis.  Fibrosarcoma: Secondary Bone Cancer:  This is the most common type of bone malignancy.  Cancers originating from the prostate gland, breast, thyroid gland, colon, and kidneys often metastasize to the skeletal system.  These cancers often seed into the long bones, ribs, and spine.  Secondary bone cancer can possess either an osteolytic or osteoblastic radiographic appearance.