• Clinical science

Osteoarthritis of the hip and knee


Osteoarthritis (OA) of the hip (coxarthrosis) and knee (gonarthrosis) is a disabling joint disease characterized by degeneration of the joint complex (articular cartilage, subchondral bone, and synovium). Although the exact etiology is unknown, risk factors include advanced age, joint overuse, obesity, previous injuries, and asymmetrically stressed joints (as in hip dysplasia, Perthes disease, etc.). Patients in the early phase of the disease present with joint stiffness and pain on initial movement and on constant, severe load bearing. During the later stages of the disease, excruciating pain may appear even during rest. Additionally, range of motion is drastically reduced and discrepancies in limb length, alignment, or stability appear. Diagnosis is predominantly based on clinical and radiological findings. Initial treatment includes lifestyle changes and physical measures (joint braces, occupational therapy, weight loss), and pain medication (NSAIDs). If medical interventions fail to improve the patient's quality of life, surgical procedures such as joint replacement may become necessary.

For more general information on osteoarthritis, see the respective article.


  • The risk of developing hip and knee OA increases with age. The number of people affected by knee and hip OA in the USA is increasing because of a general increase in average life expectancy.
  • Age: Peak incidence at initial diagnosis is 50–60 years of age.
  • Sex: > , especially in patients older than 50 years

Osteoarthritis is the most common disease of the hip joint in adults!


Epidemiological data refers to the US, unless otherwise specified.



Clinical features

See also "Clinical features” in osteoarthritis.

Walking downhill is painful with knee osteoarthritis, whereas walking uphill is painful with hip osteoarthritis!References:[5][6]


Conventional x-ray



  • Frequent exercise, minimal load → Joint-friendly exercises are also recommended after endoprosthesis implantation (swimming and cycling).
  • Weight loss may be indicated.
  • Physical therapy
  • Pain medication (WHO pain ladder)
  • Use of a forearm-supported crutch on the healthy, unaffected side when walking
  • Orthotic insoles


Indications for surgery are primarily based on the level of patient suffering.

Hip replacement

Knee joint replacement

Other surgical procedures



Complications after osteosynthesis/arthroplasty

Special complications: soft tissue ossification/myositis ossificans (heterotopic ossification)

Soft tissue and muscle ossification (heterotopic ossification) can occur congenitally or after tissue or joint injuries or surgery.

Localized course (myositis ossificans localisata)

  • Etiology
  • Clinical features: restriction of movement, muscle stiffness
  • Diagnostics
  • Treatment: radiotherapy, possibly surgery
  • Prophylactic measures against recurrence
    • Single dose radiotherapy recommended (possibly postoperative or preoperative)
    • Alternative: postoperative administration of NSAID (indomethacin)

Progressive generalized disease (myositis ossificans progressiva/fibrodysplasia ossificans progressiva)

  • Etiology: extremely rare, autosomal dominant hereditary disease
  • Pathophysiology: Fibrocytes produce bone tissue instead of scar tissue in all types of trauma.
  • Clinical features
    • Generalized ossification mainly from cranial to caudal (life-threatening if the respiratory muscles are affected)
    • Malformation of toes is frequently observed at birth.
    • During the course of the disease, large, painful, well-vascularized swellings appear at various sites, which develop into bone tissue after regression.
  • Treatment
    • No causal treatment
    • Symptomatic: NSAIDs, radiotherapy, possible surgical removal of individual lesions


We list the most important complications. The selection is not exhaustive.