Chapter 43Disorders of the Skeletal System: Trauma, Infections, Neoplasms, and Childhood Disorders
Common Joint Injuries • Injuries to muscles: strains • Injuries to ligaments: sprains, ruptures • Injuries to tendons: rotator cuff injuries • Injuries to bone surfaces • Joint dislocations • Patellar dislocation • Loose bodies • Meniscus injuries • Chondromalacia
Common Joint Injuries (cont.) • Rotator cuff injuries • Clavicle fractures • Dislocations • Bursa damage • Torn tendons • Hip injuries • Dislocation • Fracture
Knee Injuries • Meniscus injury • Patellar dislocation • Chondromalacia
Question Tell whether the following statement is true or false. Chondromalacia is the most common type of knee injury.
Answer False The most common knee injuries are tear of the ACL (anterior cruciate ligament), caused by hyperextension, and damage to the meniscus.
Fractures • Transverse • Oblique • Spiral • Comminuted • Segmental • Butterfly • Impacted
Bone Healing • Hematoma forms and fibrin network fills it • Cells grow along fibrin meshwork to form new tissue • Calcium salts deposited in new tissue • New tissue remodeled into normal shape
Question Which of the following represents the correct sequence of bone healing? • Hematoma – cartilage – bone • Hematome – elastin – fibrocartilage • Cartilage – spongy bone – compact bone • Hemangioma – spongy bone – compact bone
Answer • Hematoma – cartilage – bone Following a fracture, a hematoma forms; collagen and cartilage are deposited (soft callus); bone tissue is ossified (hard callus).
Complications Resulting from Soft Tissue Injury • Skin injury: fracture blisters • Muscle injury and swelling: compartment syndrome • Nerve injury: reflex sympathetic dystrophy • Adipose tissue or bone marrow: fat emboli
Osteomyelitis • Infection of bone • Direct contamination • Contamination through blood (hematogenous) • Miliary tuberculosis • Contamination from skin lesions
Hematogenous Osteomyelitis • In children: • Affects long bones • Purulent exudate inside bone • Damages arteries to bone • May penetrate skin or involve joints • In adults: • In vertebrae, sternoclavicular and sacroiliac joints, or pubic symphysis • Tends to affect joint space
Chronic Osteomyelitis • Areas of dead bone develop (S) • Are surrounded by new bone (IV)
Osteonecrosis • Caused by ischemia to bone due to: • Bone injury • Thrombosis or embolism • Vessel injury • Compartment syndrome inside bone (increased intraosseous pressure) • Corticosteroid associated
Question Which type of bone disorder is associated with thrombus formation or embolus? • Hematogenous osteomyelitis • Chronic osteomyelitis • Osteonecrosis • Osteoinfarction
Answer • Osteonecrosis Bone has an extensive blood supply (remember, it can’t rely on diffusion of nutrients and gases like cartilage can). When blood flow to an area of osseous tissue is disrupted because of a clot/thrombus or an embolus (a clot that has broken off and traveled), the tissue dies (necrosis).
Benign Bone Tumors • Osteoma: small bony tumor on bone surface • Chondroma: tumor made of cartilage • Osteochondroma: cartilage-capped tumor with bony stalk • Osteoclastoma: giant cell tumor • May invade bone and cause bone destruction
Malignant Bone Tumors • Osteosarcoma • Most common primary malignant bone tumor • Tends to appear in areas with the fastest bone growth • Ewing sarcoma • Chondrosarcoma • Malignant tumor of cartilage • Metastases • Most common malignancies found in bone
Manifestations of Cancer • Changes in organ function (organ damage, inflammation, and failure): pathologic fracture • Local effects of tumors (e.g., compression of nerves or veins, stretching of periosteum): pain and weakness • Nonspecific signs of tissue breakdown (e.g., protein wasting, bone breakdown): calcium release, hypercalcemia
Question Tell whether the following statement is true or false. Bone cancer is more likely to result in the release of PTH than the release of calcitonin.
Answer False As bone tissue deteriorates/breaks down, calcium is released into the blood (hypercalcemia). The hormone released in response to hypercalcemia is calcitonin (it inhibits osteoclasts). PTH is released in response to hypocalcemia.
Scenario Mr. K had lung cancer and received chemotherapy… • He is suffering from chronic back pain and weakness, and he has trouble moving his hands and grasping heavy objects • His blood calcium is elevated, and CT scans show lesions in his thoracic spine Question • What are two possible explanations for his weakness?
Variations in Normal Growth and Development • Torsional deformities • In-toeing and out-toeing • Internal and external tibial torsion • Internal and external femoral torsion • Genu varum and genu valgum
Hereditary and Congenital Deformities • Congenital dysplasia of the hip • Foot deformities (clubfoot) • Talipes varus: foot inverted at heel • Talipes valgus: foot everted at heel • Talipes equinus: plantarflexion, toes lower than heel • Talipes calcaneus: dorsiflexion, heel below toes
Abnormal Bone Formation • Osteogenesis imperfecta • Mutations in genes for collagen • Juvenile osteochondrosis • Osteonecrotic • Local degeneration of ossification centers followed by disordered regeneration • Abnormal ossification of cartilaginous tissue
Scoliosis • Postural • Structural • Congenital • Neuromuscular • Idiopathic