• Clinical science

Osteoarthritis of the hip and knee

Abstract

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.

Epidemiology

  • 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!

References:[1][2][3]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

References:[3][4]

Clinical features

See also "Clinical features” in osteoarthritis.

  • Hip Osteoarthritis
    • Pain in the groin area and above the greater trochanter
    • Increased contracture in the flexor, external rotation, and adduction position → antalgic gait
    • Early signs: limited and painful internal rotation of the hip joint
    • Pain on palpation: greater trochanter, groin
    • Positive Thomas test
  • Knee Osteoarthritis
    • Function-limiting knee pain
    • Knee swelling which increases on activity
    • Mechanical instability, locking, catching sensation
    • In case of patello-femoral osteoarthritis: positive Patellar grind test (pain on movement of the patella)

Walking downhill is painful with knee osteoarthritis, whereas walking uphill is painful with hip osteoarthritis!References:[5][6][7]

Diagnostics

Conventional x-ray

Treatment

Conservative

  • 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

Surgery

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

Hip replacement

Knee joint replacement

  • Nonconstrained prosthesis
    • Unicondylar knee replacement
      • Description: unicompartmental prosthesis of the femoral and tibial articular surface with insertion of a plastic sliding surface (mainly polyethylene) between both prosthetic components
      • Indication: unilateral osteoarthritis of the inner and outer surface of the joint; more frequently internal in varus gonarthrosis
    • Bicondylar knee replacement(total knee replacement)
      • Description
        • Both condyles of the femur and the joint surface of the articular surface of the tibial head are replaced.
        • Insertion of a plastic sliding surface (mainly polyethylene) between both prosthetic components
        • If necessary, additional replacement of the posterior surface of the patella (tricondylar knee replacement)
      • Indication: knee osteoarthritis, which is nonresponsive to conservative treatment and severely restricts the patient's quality of life
    • Patellofemoral joint replacement
      • Description: prosthetic replacement of the femoral trochlear (= patella condyle) and the rear surface of the patella
      • Indication: mainly isolated degenerative alterations of the femoropatellar joint
  • Constrained prosthesis: rotating hinge knee prosthesis
    • Indication: severe knee osteoarthritis with ligament insufficiency and femorotibial rotational malalignment
    • Description: analogous to the bicondylar knee prosthesis; However, the femoral and tibial components are larger shaft prostheses that are more deeply anchored and are connected via a movable axis.
  • Postoperative deep venous thrombosis prophylaxis is to be administered for knee replacement and any surgery to correct a fracture located close to the knee joint
      • Perioperative start
      • For 11–14 days postoperatively

Other surgical procedures

  • Corrective osteotomy (valgus or varus)
  • Arthrodesis: surgical fusion of the joint; very rare in osteoarthritis of the hip and knee

References:[8][3][9][10][11]

Complications

See also complications after osteosynthesis/arthroplasty.

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

References:[12][13][14]

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