Chapter 16: Musculoskeletal System
Prevalence for most conditions varies by gender.
o EX: Osteoarthritis (OA) more common in women, especially in
... [Show More] the knee.
Approach to musculoskeletal disorders
characterize the patient’s complaint in terms of four key features. Is the joint problem:
o Articular or extra-articular
o Acute (usually <6 weeks) or chronic (usually >12 weeks)
o Inflammatory or noninflammatory
o Localized (monoarticular) or diffuse (polyarticular)
Articular structures include joint capsule and articular cartilage, the synovium and synovial
fluid, intra-articular ligaments, and juxtaarticular bone.
o Articular cartilage is composed of a collagen matrix containing charged ions and water,
allowing the cartilage to change shape in response to pressure or load, acting as a
cushion for underlying bone. Synovial fluid provides nutrition to the adjacent relatively
avascular articular cartilage.
o Articular disease typically involves swelling and tenderness of the entire joint,
crepitus, instability, “locking,” or deformity, and limits both active and passive
range of motion due to either stiffness or pain.
Extra-articular structures include periarticular ligaments, tendons, bursae, muscle, fascia,
bone, nerve, and overlying skin.
o Bursae are pouches of synovial fluid that cushion the movement of tendons and
muscles over bone or other joint structures
o Extra-articular disease typically involves “point or focal tenderness in regions
adjacent to articular structures” and limits active range of motion. Extra-articular
disease rarely causes swelling, instability, or joint deformity.
Age also provides clues to causes of joint pain:
o If age <60 years, consider repetitive strain or overuse syndromes like tendinitis or
bursitis, crystalline arthritis (gout; crystalline pyrophosphate deposition disease [CPPD])
(males), rheumatoid arthritis (RA), psoriatic arthritis and reactive (Reiter) arthritis (in
inflammatory bowel disease [IBD]), and infectious arthritis from gonorrhea, Lyme
disease, or viral or bacterial infections.
o If age >60 years, look for OA, gout and pseudogout, polymyalgia rheumatica (PMR),
osteoporotic fracture, and septic bacterial arthritis.
three primary types of joint articulation:
o synovial joints
freely moveable
bones of these joints do not touch
bones are covered by articular cartilage and separated by synovial cavity that
cushions joint movement
A synovial membrane lines the synovial cavity and secretes a small amount of
viscous lubricating fluid, the synovial fluid
Surrounding the joint is a fibrous joint capsule, which is strengthened by
ligaments extending from bone to bone
ex: knee; shoulder
o cartilaginous
slightly moveable
ex: vertebral bodies of the spine; symphysis pubis
Fibrocartilaginous discs separate the bony surfaces.
At the center of each disc is the nucleus pulposus, somewhat gelatinous
fibrocartilaginous material that serves as a cushion or shock absorber between
bony surfaces
o fibrous
immovable
The bones are almost in direct contact
intervening layers of fibrous tissue or cartilage hold the bones together
ex: skull sutures
Types of synovial joints:
o Spheroidal (ball and socket)
movement: wide-ranging–flexion, extension, abduction, adduction, rotation,
circumduction
ex: shoulder; hip
o hinge
movement: Motion in one plane; flexion, extension
ex: Interphalangeal joints of hand and foot; elbow
o condylar
movement: allow flexion, extension, rotation, and motion in the coronal plane.
knee; temporomandibular joint
bursae roughly disc-shaped synovial sacs that ease joint action and allow adjacent muscles
or muscles and tendons to glide over each other during movement....... [Show Less]