CHAPTER 51

ALTERATIONS IN MUSCULOSKELETAL FUNCTION:

TRAUMA, INFECTION, AND DISEASE

BONE AND JOINT TRAUMA• Bones protect internal organs, contribute to

mineral homeostasis, produce blood cells, and provide muscle attachment sites that facilitate body movement• Bone is one of the body’s hardest

structures, and most dynamic and metabolically active tissues• It is vascular with a capacity for repair

TYPES OF BONE• Cortical bone forms the cortex (outer shell)

of the bone; when tension stress exceeds the tolerance of cortical bone, fracture can occur on the convex side of the bend• Cancellous bone is found in the interior of

the bone and has a spongy, or lattice-like appearance; provides structural support but does not tolerate compression stress

FRACTURE• A fracture is a break in continuity of a bone,

an epiphyseal plate, or a cartilaginous joint surface• Trauma may also occur to adjacent tissue

FRACTURE (CONT.)

TYPES OF FRACTURE• Different types of fracture depend on the

type of tension stress involved• Fractures can be classified according to the

orientation of the break as transverse, longitudinal, oblique, or spiral• A comminuted fracture consists of more

than one fracture line and more than two bone fragments• A greenstick fracture is an incomplete break

EXTENT OF FRACTURE• A nondisplaced fracture occurs when the

fragments remain in alignment and position, whereas a displaced fracture is one in which the ends of fracture fragments are separated• Fractures are classified as open or

compound when the skin is penetrated and as closed or simple when the skin is not broken

HEALING PROCESS• Cortical bone fracture results in torn blood

vessels within the haversian system• Clotting occurs at the fracture site• Avascular bone is replaced by living bone

through resorption and bone deposition• Callus formation leads to new bone

formation at the edges of the periosteum• Remodeling occurs with replacement of

mature lamellar bone

HEALING PROCESS (CONT.)

COMPLICATIONS IN BONE HEALING

• Delayed healing can include delayed union, malunion, or nonunion• Treatment includes bone grafting,

internal/external fixation, electrical bone stimulation, or a mixture of these• Soft tissue complications may include

compartment syndrome or neovascular injury

DISLOCATIONS AND SUBLUXATIONS

• Complete separation of joint articulating surfaces is termed dislocation• Subluxation refers to partial separation• A considerable amount of tissue damage

occurs with dislocation or subluxation• Evaluation of fracture is necessary

SCOLIOSIS• Lateral curvature of the spine resulting in

an S- or a C-shaped spinal column with vertebral column• Nonstructural scoliosis resolves when the

patient bends to the affected side; structural scoliosis fails to correct itself on forced bending against the curvature and has vertebral rotation• Treatment may include bracing, exercises,

or surgical interventions with spinal alignment, fusion, and internal fixation

ALTERATIONS IN BONE MASS AND STRUCTURE

OSTEOPOROSIS• The most common metabolic disease that

occurs when the rate of bone resorption is greater than that of bone formation• Hormone deficiencies (estrogen, androgen),

poor calcium intake, and lack of use are common factors in the rate of bone loss• Treatment may include calcium and vitamin

D supplements, exercise, estrogen replacement therapy, bisphosphonates, or recombinant human parathyroid hormone

RICKETS AND OSTEOMALACIA• Vitamin D deficiency is associated with

rickets and osteomalacia, disorders characterized by soft, weak bones• Osteomalacia due to an inadequate

concentration of vitamin D, calcium or phosphorus, poor vitamin D metabolism, and/or renal disease• Treatment includes vitamin D, calcium, or

phosphorus supplementation

PAGET DISEASE• May be genetic or due to a viral infection

that affects osteoclastic function leading to aberrant bone remodeling• Painful bone deformities or bone fractures

may develop• During active stages treatment is focused

on preventing deformity and fracture with calcitonin or bisphosphonates

INFECTIONS OF THE BONE• Hematogenous osteomyelitis occurs when

the infectious agent is introduced by blood from infection elsewhere in the body• May occur due to burns, sinus disease,

trauma, malignant tumor necrosis, periodontal infection or an infected pressure ulcer• Staphylococcus aureus most common

pathogen

INFECTIONS OF THE BONE (CONT.)

• Direct infection can occur due to open fracture, penetrating wounds, surgical contamination, or insertion of prostheses, metal plates, or screws

OSTEOMYELITIS• Severe pyogenic infection of bone and local

tissue• Organisms reach the bone through the

bloodstream, adjacent soft tissue or direct introduction of the organism into the bone• Treatment: 4-6 wk of antibiotic therapy;

abscess formation may require debridement; chronic infection may occur

TUBERCULOSIS• Infection is spread via lung or

lymphohematogenous drainage due to Mycobacterium tuberculosis• Most common site is the vertebral column• Treatment includes long-term combination

antibiotic therapy for 9-12 months; may be complicated by drug resistance; surgical intervention may be needed for severe deformities or neurologic deficits

BONE TUMORS• Neoplasms can be benign or malignant• Malignant neoplasms are referred to as

sarcomas• Metastatic lesions spread to bone from

primary carcinomas• Common sites are the vertebral bodies,

pelvis, proximal ends of the femur and humerus, and ribs

OSTEOCHONDROMA• Most common bone tumor• Cartilage-forming benign tumor that is

hereditary and usually occurs in those >30 years of age• Pressure on surrounding tissue can cause

pain• Usually located on the metaphyses of long

bones, such as the proximal end of the tibia and distal part of the femur, the shoulder, and pelvis

CHONDROMA• Cartilage-forming tumor in bone that can be

located in the medullary cavity or in the subperiosteal layers of bone• Arises from remnants of epiphyseal

cartilage• Typically located in the small bones of the

hands and feet • May erode cortex of bone and expand the

contour• Usually occurs in those 30-40 years of age

OSTEOID OSTEOMA• A painful but benign bone-forming tumor • Pain is usually sharp or dull, worse at night,

and alleviated by aspirin or NSAIDs• Often found in the cortex of the tibia and

femur• Usually occurs in those 10-20 years of age

GIANT CELL TUMOR• A benign but aggressive tumor with richly

vascularized tissue consisting of plump spindle-shaped cells and numerous giant cells• Can undergo transformation to sarcomas• Occurs between 20 and 40 years of age• Located in distal end of the femur, proximal

end of the tibia, distal part of the radius, and proximal end of the humerus

OSTEOSARCOMA• Extremely malignant bone-forming tumor

and most common primary malignant bone tumor• Formation of bone or osteoid by tumor cells• Occurs in children and young adults• Located in distal end of the femur, proximal

end of the tibia, fibula, humerus and flat bones of the pelvis, skull, scapula, ribs, or spine

OSTEOSARCOMA (CONT.)• Treated with conservative surgery and

chemotherapy; may require amputation

CHONDROSARCOMA• Malignant cartilage-forming tumor that

develops slowly; tends to develop in the pelvic and shoulder girdles and the proximal ends of long bones• Characterized by formation of cartilage by

tumor cells• Occurs in those 30-60 years of age

EWING SARCOMA• Third most common primary sarcoma; a

rapidly growing malignant round cell tumor• Develops in the long bones of children• Composed of densely packed small cells

with round nuclei, may metastasize to lungs; pain is a dominant symptom• Treatment includes radiotherapy and

possible adjunct surgical therapy

MULTIPLE MYELOMA• Slowly growing bone marrow malignancy

with neoplastic proliferation of a single clone of plasma cells• Homogeneous immunoglobulin is present in

urine and serum• Pain is predominant symptom • Treatment often requires aggressive

combination chemotherapy or local radiation

SOFT-TISSUE INJURIES• Contractile tissue is composed of structures

involved in the contraction of muscle and includes not only the muscle belly but also the tendon and bony insertion• Inert tissue possesses no ability to contract

or relax

LIGAMENT INJURIES• Occur when loading exceeds the

physiologic range of motion• Microfailure precedes total failure• Classified by extent of tear: mild, moderate,

or severe• Symptoms occur as pain with weight

bearing and acute swelling• Treatment dependent on degree of tear;

surgical restoration of ligament continuity may be required in severe injury

JOINT CAPSULE INJURIES• Injury causes increase in vascularity and

development of fibrous tissue leads to a thick capsule• Injury or edema in the joint that causes

scarring in the lax section of the capsule prevents full range of motion• Altered flow of synovial fluid prevents fluid

diffusion into and out of cartilage and causes compression and distention

JOINT CAPSULE

INJURIES TO FASCIAE AND BURSAE

• Fasciae are connective tissues of the body arranged in sheaths that envelop muscles• Bursae are pockets of connective tissue

lined with synovium in locations between muscles or between muscle or tendon and bone

INJURIES TO NERVES, NERVE ROOTS, AND DURA MATER

• Trauma to any soft tissue may lead to adhesive constriction of the nerve, nerve root, or dura mater• Irritation or entrapment of a nerve causes

pain that radiates along the structures innervated by the nerve• Symptoms include altered sensation, motor

weakness, and diminished reflexes

INJURIES TO NERVES, NERVE ROOTS, AND DURA MATER

(CONT.)

INJURY TO TENDONS• Range from mild to complete tear• Tendinitis may develop from infection,

direct injury or injury from repetitive motion• Tendons are injured when the stress placed

on them is greater than the fibers can tolerate

MUSCLE AND TENDON STRAINS• Categorized by the severity of injury• Grade I: minute tear of connective tissue and

muscle fiber• Grade II: tear of a large portion of the contractile

unit, with a segment still intact• Grade III: total rupture or loss of continuity of the

contractile structure

BLUNT TRAUMA• Can cause bleeding into the muscle belly;

may lead to an inability to contract the muscle; may coagulate and calcify; results in myositis ossificans• Calcification prevents a normal and strong

contraction of the muscle involved

COMPARTMENT SYNDROME• Results from trauma to soft tissue caused

by the unyielding structure of inert tissue• Causes: decreased compartment size,

increased compartment content, or externally applied pressure• Edema causes increase in pressure in the

compartment; pressure reduces capillary flow; muscle and nerves become ischemic• Symptoms may include pain, paresthesia,

pale skin, and diminished pulse

EVALUATION OF CONTRACTILE INJURIES

• Patterns of function deal with pain and strength rather than excessive motion noted during evaluation of ligamentous injury • Strong and pain free • Strong and painful • Weak and painful• Weak and pain free

SOFT-TISSUE HEALING AFTER TRAUMA

• Disruption of circulatory and lymphatic systems; hemorrhage, fluid loss, cell death• Norepinephrine causes constriction of

vessels; serotonin and platelets prolong vasoconstriction• Inflammation; release of histamines causes

vasodilation and increased permeability of venules

WOUND REPAIR• Inflammatory response prepares injured

tissue• Granulation tissue develops in the wound

space• Reepithelialization of the wound surface

occurs; formation of basement membrane• Wound tensile strength is a result of

deposition of collagen• Revascularization ensures survival of the

new tissue

WOUND REPAIR (CONT.)• Wound closure or contraction is the final

phase of healing

DISEASES OF SKELETAL MUSCLE

• Skeletal muscle most abundant tissue in the body; accounts for 40% of body weight• Skeletal muscle performs dynamic and

static work• Muscle atrophies in response to disuse and

immobilization, and hypertrophies in response to increased stress

MUSCULAR DYSTROPHY• A group of genetically determined

myopathies characterized by progressive muscle weakness and degeneration • Muscle tissue is replaced by fat and fibrous

connective tissue• Classified by the pattern of inheritance, age

of onset, and distribution of muscular weakness

DUCHENNE MUSCULAR DYSTROPHY

• Most common and most severe form• Inherited as X-linked trait, thus affects only

men• Muscle cells are deficient in the protein

dystrophin; weakens the cell membrane and allows extracellular fluid to leak into the cell• Calf muscles enlarged, distal muscle

involvement• Treatment includes corticosteroid therapy

and preservation of function

BECKER MUSCULAR DYSTROPHY

• Milder form of inherited muscle degeneration• Genetic mutation leads to production of a

reduced amount of an abnormal dystrophin protein and slower muscular degeneration• Calf hypertrophy prominent, often painful,

with progressive loss of strength and ability to ambulate

FACIOSCAPULOHUMERAL MUSCULAR DYSTROPHY

• Rare inherited autosomal dominant trait that affects the muscles of the shoulder girdle and face• Facial muscles involved early with later

involvement of scapular and upper arm musculature• Progresses slowly with periods of arrest and

can ultimately involve more distal muscles

MYASTHENIA GRAVIS• Chronic autoimmune disease; affects the

neuromuscular function of voluntary muscles and characterized by profound muscle weakness and fatigability• Acetylcholine receptor antibodies produced

that destroy or block acetylcholine receptors of the muscle end-plate of the neuromuscular junction

MYASTHENIA GRAVIS (CONT.)• Anticholinesterase inhibitors,

corticosteroids, intravenous immune globulin, plasmapheresis, and immunosuppressive agents may be used

FIBROMYALGIA SYNDROME• Cause remains unknown• Characterized by widespread pain in all

quadrants of the body; additional symptoms may include fatigue, insomnia, depression, and concentration problems• Treatment is multidimensional including

exercise, counseling, and drug therapy to improve sleep, mood, and pain