Osteoarthritis of the hip and knee

Osteoarthritis of the hip and knee is characterized by joint degeneration, which can lead to functional impairment. Although the exact etiology is unknown, risk factors include older age, overuse of the joint, obesity, previous injuries, and asymmetrically stressed joints. Patients often present with joint stiffness and pain, which can progress to severe pain and functional limitation. Osteoarthritis is a clinical diagnosis, supported by radiological findings. Initial management includes nonpharmacological measures such as weight loss, physical therapy, and the use of assistive devices (e.g., canes, braces), and short-term pharmacotherapy for pain management. If conservative measures do not improve the patient's quality of life and joint destruction is severe, surgical procedures such as arthroplasty may be indicated.

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

The risk of developing hip and knee osteoarthritis increases with age. ^[1][2]

• 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.

• See “Etiology” in osteoarthritis. ^[3]
• Primary osteoarthritis: idiopathic
• Secondary osteoarthritis
  • Hip osteoarthritis due to Legg-Calvé-Perthes disease, slipped capital femoral epiphysis, developmental dysplasia of the hip, hemochromatosis, gout, stiffened ipsilateral knee joint
  • Knee osteoarthritis due to genu valgum, genu varum, cruciate ligament rupture, meniscal tear

See also "Clinical features of osteoarthritis.” ^[4]

• 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
    • Function: test for hip flexion contracture
    • Position: supine
    • Procedure: Examiner passively flexes the hip joint opposite to the affected side to a maximum to compensate lumbar lordosis.
    • Positive test: If flexion contracture is present, the ipsilateral leg will simultaneously flex independently as a reflex.
• 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)
  • Cartilage damage usually begins medially and may lead to genu varum (bowing of legs)

Walking downhill is painful with knee osteoarthritis, whereas walking uphill is painful with hip osteoarthritis!

Osteoarthritis is a clinical diagnosis. Diagnostic studies may be indicated if there is clinical uncertainty or to exclude alternative diagnoses (see “Diagnosis of osteoarthritis” and “Differential diagnoses of inflammatory arthritis”). ^[5]

Plain radiography ^[5]

• Patient position: Obtain multiple views (e.g., anteroposterior, lateral) of the affected joints, if possible. ^[6]
  • Hip: Patient may be weight-bearing or non-weight-bearing.
  • Knee: Patient should be standing.
• Supportive findings
  • Radiological signs of osteoarthritis ^[5]
  • Standing views of the knee may show: ^[6]
    • Joint space narrowing
    • Uneven pressure distribution: e.g., patella lateralization, genu valgum, genu varum

X-rays may appear normal in the early stages of osteoarthritis. The absence of radiological signs of osteoarthritis does not rule out osteoarthritis. ^[5]

Additional studies ^[5]

Consider to rule out complications and alternative diagnoses (e.g., fractures, infection), and for surgical planning. ^[5][6]

• Imaging
  • MRI, ultrasound, or CT scan of the affected joint
  • See “Other imaging modalities” and “Further investigations” in “Diagnostics of osteoarthritis.”
• Laboratory studies: usually normal in osteoarthritis ^[7]

Approach ^[8][9]

• Recommend nonpharmacological management for all patients (see “Management of osteoarthritis”).
• Initiate pharmacological therapy for pain management, as needed.
• Indications for referral to orthopedic surgery include:
  • Persistent symptoms despite multiple trials of conservative management ^[5]
  • Symptoms associated with radiographic evidence of osteonecrosis or moderate-to-severe osteoarthritis ^[9]

Conservative management ^[5][10]

• Nonpharmacological management ^[8][10]
  • Weight loss (if overweight or obese) and exercise are recommended for all patients.
  • Physical therapy and use of assistive devices (e.g., cane, knee braces) may help improve pain and mobility.
  • There is limited evidence to support the routine use of oral supplements (e.g., fish oil, vitamin D, glucosamine, chondroitin sulfate) or orthotic insoles. ^{[5][8][10][11]}
• Pharmacotherapy ^[5]
  • First line: NSAIDs
  • Patients who cannot tolerate or do not improve with NSAIDs: See “Management of osteoarthritis” for alternative agents.
  • Intraarticular glucocorticoid injection: Consider for local, short-term relief in patients with osteoarthritis of the hip and knee.
    • Intraarticular triamcinolone or methylprednisolone ^[12]
    • Use ultrasound to guide hip joint injections.
    • Risks: cartilage loss, joint space infection
  • Intraarticular hyaluronic acid: may be considered for osteoarthritis of the knee ^[8][11][13]

Pharmacotherapy should only be used as a short-term treatment in symptomatic patients; long-term therapy is associated with many adverse effects.

Surgery

Arthroplasty

• Total or partial joint replacement may be considered for advanced joint destruction with pain and functional impairment not adequately controlled by conservative management. ^[5]
• Type of surgery depends on the joint involved and the extent of involvement; indications include:
  • Total hip arthroplasty
    • Primary and secondary osteoarthritis of the hip
    • Femoral neck fracture in patients with concomitant osteoarthritis ^[14][15]
  • Total knee replacement: osteoarthritis of one or more compartments of the knee joint ^[16][17]
  • Partial knee replacement: isolated osteoarthritis of one or two compartments of the knee joint ^[6][16][17]
• See also “Complications after arthroplasty.”

Patients undergoing total joint replacement should receive perioperative antibiotic prophylaxis and VTE prophylaxis. Early postoperative physiotherapy can reduce the duration of hospitalization and improve pain and function. See “Perioperative considerations” in “Treatment of osteoarthritis” for details. ^[18]

Osteotomy

• May be considered to delay the development or worsening of osteoarthritis in young individuals (< 60 years of age) with unicompartmental osteoarthritis (e.g., due to trauma) ^[10][16][19]
• Types and indications include:
  • High tibial osteotomy: osteoarthritis of the medial compartment of the knee and associated genu varus
  • Low femoral osteotomy: osteoarthritis of the lateral compartment of the knee and associated genu valgum
  • Hip osteotomy: hip dysplasia and no significant osteoarthritis

Arthroscopy

• Consider for osteoarthritis and a concomitant meniscal tear that does not respond to conservative management ^[10][19]

• One-Minute Telegram 60-2022-3/3: Yoga improves function in knee OA (but only if you actually do it).

Interested in the newest medical research, distilled down to just one minute? Sign up for the One-Minute Telegram in “Tips and links” below.