Chapter 43
Disorders of the Skeletal System:
Trauma, Infections, Neoplasms,
and
Childhood Disorders
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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
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Common Joint Injuries (cont.)
• Rotator cuff injuries
– Clavicle fractures
– Dislocations
– Bursa damage
– Torn tendons
• Hip injuries
– Dislocation
– Fracture
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Knee Injuries
• Meniscus injury
• Patellar dislocation
• Chondromalacia
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Question
Tell whether the following statement is true or false.
Chondromalacia is the most common type of knee injury.
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Answer
False
The most common knee injuries are tear of the ACL
(anterior cruciate ligament), caused by hyperextension,
and damage to the meniscus.
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Fractures
• Transverse
• Oblique
• Spiral
• Comminuted
• Segmental
• Butterfly
• Impacted
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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
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Question
Which of the following represents the correct sequence of
bone healing?
a. Hematoma – cartilage – bone
b. Hematome – elastin – fibrocartilage
c. Cartilage – spongy bone – compact bone
d. Hemangioma – spongy bone – compact bone
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Answer
a. Hematoma – cartilage – bone
Following a fracture, a hematoma forms; collagen and
cartilage are deposited (soft callus); bone tissue is
ossified (hard callus).
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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
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Osteomyelitis
• Infection of bone
– Direct contamination
– Contamination through blood (hematogenous)
º Miliary tuberculosis
– Contamination from skin lesions
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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
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Chronic Osteomyelitis
• Areas of dead bone develop (S)
• Are surrounded by new bone (IV)
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Osteonecrosis
• Caused by ischemia to bone due to:
– Bone injury
– Thrombosis or embolism
– Vessel injury
– Compartment syndrome inside bone
(increased intraosseous pressure)
– Corticosteroid associated
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Question
Which type of bone disorder is associated with thrombus
formation or embolus?
a. Hematogenous osteomyelitis
b. Chronic osteomyelitis
c. Osteonecrosis
d. Osteoinfarction
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Answer
c. 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).
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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
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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
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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
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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.
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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.
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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?
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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
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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
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Abnormal Bone Formation
• Osteogenesis imperfecta
– Mutations in genes for collagen
• Juvenile osteochondrosis
– Osteonecrotic
º Local degeneration of ossification centers
followed by disordered regeneration
– Abnormal ossification of cartilaginous tissue
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Scoliosis
• Postural
• Structural
– Congenital
– Neuromuscular
– Idiopathic
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