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  • Knee arthritis
  • Knee degenerative joint disease

  • 715 Osteoarthrosis and allied disorders
  • 715.16 Osteoarthrosis localized primary involving lower leg
  • 715.26 Osteoarthrosis localized secondary involving lower leg
  • 715.36 Osteoarthrosis localized not specified whether primary or secondary involving lower leg
  • 715.9 Osteoarthrosis, unspecified whether generalized or localized
  • 715.95 Osteoarthrosis, unspecified whether generalized or localized involving pelvic region and thigh

  • M17.10 Unilateral primary osteoarthritis, unspecified knee
  • M17.5 Other unilateral secondary osteoarthritis of knee
  • M17.9 Osteoarthritis of knee, unspecified

  • 4D: Impaired joint mobility, motor function, muscle performance, and range of motion associated with connective tissue dysfunction1
  • 4F: Impaired Joint Mobility, Motor Function, Muscle Performance, Range of Motion, and Reflex Integrity Associated With Spinal Disorders2
  • 4H: Impaired Joint Mobility, Motor Function, Muscle Performance, and Range of Motion Associated With Joint Arthroplasty3
  • 4I: Impaired Joint Mobility, Motor Function, Muscle Performance, and Range of Motion Associated With Bony or Soft Tissue Surgery4


  • Most common form of arthritis
  • Degenerative
  • Commonly affects hip and knee joints, weight-bearing joints
  • Can also affect spinal facet joints
  • Associated with increasing age, obesity, female sex and race/ethnicity
  • Associated with abnormal loading of the joints
  • Characterized by joint pain
  • Arthrosis
  • Osteoarthrosis
  • Polyarthrosis
  • Degenerative joint disease

Essentials of Diagnosis

  • Radiography is standard method for diagnosis
  • Kellgren-Lawrence (KL) Grade ≥ 2 (definite radiographic OA)5
  • Osteophytes, joint-space narrowing, sclerosis
  • Cartilage lesions, bone marrow lesions, synovitis, effusion, and subchondral bone attrition/sclerosis
  • Erosion of articular cartilage
  • Synovial hyperplasia
  • Fibrosis
  • Inflammatory cell infiltration
    • With or without OA symptoms
  • Conventional radiograph is most commonly used tool in OA
  • Diagnosis based on careful history and physical examination, imaging studies, laboratory examination, exclusion of other possible diseases

General Considerations

  • Low bone mineral density (BMD)
  • Repetitive joint use or loading
  • Joint alignment
  • Leg-length discrepancy or inequality (LLD)
  • Bone or joint morphology
  • Calcification (of the knee meniscus)
  • Bone formation, cyst formation
  • Thickening of subchondral bone plate, osteosclerosis
  • Overall joint dysfunction
  • Joint swelling and inflammation (in certain cases, severe cases)
  • Joint pain
  • Morning stiffness
  • Long-term disease
  • Secondary problems
    • Muscle atrophy and weakness
    • Bony protrusion/prominence
    • Joint deformity
    • Difficulty walking
    • Difficulty with ADLs


  • Aging (onset middle- to old-age)
  • Women more commonly affected than men
  • African American and Caucasian more commonly affected
  • May affect approximately 12% of the population (U.S. and other developed countries)6

Signs and Symptoms

  • Joint pain
  • Aching joint
  • Joint stiffness
  • Muscle weakness
  • Muscle atrophy
  • Crepitus
  • Bony enlargement
  • Limited joint range of motion (ROM)
  • Joint line tenderness
  • Joint deformity in severe cases
  • Activity limitation

Functional Implications

  • Limited mobility
  • Limited or restricted household and work-related activity
  • Decreased activity and participation overall

Possible Contributing Causes

  • Chronic factors affecting the joint such as obesity, BMD, ...

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