Ortho Exam 2 - Lecture 8

Bone Diseases

Rheumatoid Arthritis - define

systemic inflammatory disease, affects the lining of multiple joints (synovial membrane) and can affect other organs

RA Etiology and Pathology

environmental and genetic factors

Synovitis - inflam. of synovial tissues

Destruction - proteolytic enzymes help regulate inflam. response

Deformity - articular destruction, capsular stretching, tendon rupture

RA sympotoms

pain, swelling, and redness in joints with fatigue and prolonged stiffness after rest

pain, joint destruction, deformity, instability

RA X-ray changes

joint space narrowing, pero-articular osteopenia, cartilage erosions, x-rays DO NOT provide differential diagnosis of RA

Osteoarthritis

chronic joint disorder, progressive softening and disintegration of articular cartilage accompanied by new growth of cartilage and bone at the joint margins and capsular fibrosis. Most common

OA risk factors

age, females, abnormal joint alignment, hereditary, joint injury/overuse, obesity

OA symptoms

gradual onset, steady/intermittent pain in a joint.

pain, swelling, stiffness, deformity, instability, loss of function

3 mechanisms of OA

mechanical disparity: stress applied to articular cartilage and strength of articular cartilage

increased stress: increased load (BW or activity, and decreased area (varus knee or dysplastic hip)

weak cartilage: age, stiff, soft, abnormal bony support

OA Degeneration Mechanism

loss of compressibility, vertical fractures from surface to cartilage substance, pitted surface, large ulcers, exposed bone

deeper chondrocytes proliferate, forming clusters - Weichselbaum’s lacunae

OA Etiology

genetic, metabolic, hormonal, mechanical, and aging etiology

OA X-ray changes

narrowing of articular cartilage, radiodensity of subchondral bone, radiolucencies, peripheral osteophytes (bone spurs)

key differences between OA and aging

Osteoporosis Definition

progressive systemic skeletal disorder - low bone mass and mineral density, deterioration of micro-architecture, compromised bone strength

bone resorption > bone formation

How to detect deviations for diagnosing osteoporosis

BMD measurement relative to the typical peak bone mass of healthy 30-year-old of the same gender and race

standard deviation from peak mass is called the T score (used for people >50 years)

Why use T score in post - menopausal women and men over 50?

predicts risk of future fracture. A higher, positive t-score means normal bone density. negative t scores means low bone mass or disease

osteopenia (T-score)

reduced rate of bone formation and bone mass, defined as less than -1.0 and greater than -2.5

osteoporosis (T-score)

-2.5 or lower, aka a bone density 2.5 standard deviations below the mean of a 30 year old

When can you see changes in radiographic structural effects

after about 30% of bone is lost

Osteomalacia/Rickets Definition

uncalcified “soft bones” due to insufficient mineral or osteoblast dysfunction, osteoid accumulates and doesn’t mineralize properly, and vitamin D deficiency. this can cause curvature

Rickets - osteomalacia in children

Paget’s Disease (Osteitis Deformans) Definition

bone enlargement and thickening

increase osteoclast/blast activity = increased bone turnover

Osteonecrosis (Avascular Necrosis) Definition

results from bone ischemia, due to trauma, corticosteroid use, idiopathic cases

pain with activity, pain at rest, focal articular changes on radiographs

Perthes’ Disease

necrosis of the secondary ossification center of the proximal femoral epiphyses, with subsequent remodeling of regenerated bone

impacts growth plate, pediatric patients