Knee osteoarthritis

Knee osteoarthritis is a degenerative disease of the knee joint. It is more common in people older than 40 years. Women have greater chance to be affected.

Signs and symptoms

Some of the signs and symptoms associated with knee osteoarthritis include:

• Pain
• Stiffness
• Decreasing range of motion
• Muscle weakness and atrophy (particularly of quadriceps femoris, muscle on front of thigh) due to inactivity or stiffness
• Crepitus
• Effusion-increase in quantity of synovial fluid leading to swelling
• Deformity
• Baker's cyst (a harmless but sometimes painful collection of joint fluid behind the knee)

Causes

Osteoarthritis of the knee is predominately considered a "wear and tear" process, where there is gradual degradation of the hyaline cartilage that covers the articulating surfaces of the bones in the knee joint. In most people, the disease is either post-traumatic or hereditary.

Other causes or contributing factors may include:

• Trauma

• Elements injury of the knee joint
  • Tear of meniscus
  • Partial menisectomy via arthroscopy

• Recurrent patellar dislocation and patella fracture

• Interarticular fractures of the knee and knee dislocations

• Arthritis (such as rheumatoid arthritis, infectious arthritis, etc.)

• Deformities of the knee joint that include:
  • Genu varum
  • Genu valgum
  • Genu recurvatum (Knee hyperextension)
  • Knee flexion deformity

• Ligamentous instability
  • Anterior cruciate ligament
  • Posterior cruciate ligament
  • Medial collateral ligament
  • Lateral collateral ligament
• Obesity
• Genetics factors
• Osteochondritis dissecans disease
• Meniscal cyst
• Discoid meniscus

Pathophysiology

The most important characteristic of knee osteoarthritis is degeneration of the articular cartilage in the knee joint. Osteoarthritis of the knee can involve one, two, or all three compartments of the knee:

• Medial or lateral compartments of the tibiofemoral joint (between the femur and the tibia)
• Patellofemoral joint (between the femur and patella)

Diagnosis

• Joint space narrowing
• Osteophyte formation at the joint margins
• Subchondral Sclerosis (new subchondral bone formation in response to stress on the bone)
• Subchondral Cyst formation (joint fluid under pressure gets into cracks in the cartilage)

Treatment

• Pharmacologic therapy (Tylenol; NSAIDS such as ibuprofen, naprosyn, etc.; glucosamine/chondroitin)

• Intra-articular injection (steroid or hyaluronic acid preparations such as Synvisc or Supartz)

• Weight loss (if obesity or overweight)

• Low Impact Aerobic Exercise (walking, treadmill, elliptical, bike or stationary bike, swimming or water aerobics)

• Physical therapy. Aims of physical therapy include:
  • Pain and spasm relief
  • Reducing stiffness
  • Muscles strengthening
  • Increasing range of motion
  • Increasing flexibility
  • Gait training
  • Balance improvement
  • Patient education
  • Increasing functional activities

• Hydrotherapy

• Assistive devices (cane, walker)

• Surgical treatment (when nonsurgical management fails to provide relief)

Surgery

Surgical operations can include the following:

• Total or partial knee replacement (Arthroplasty of the knee)
• Femoral osteotomy
• Tibial osteotomy

• Arthroscopic debridement (so-called "clean out"). Debridement may be done for these knee problems:
  • Damaged cartilage
  • Damaged meniscus
  • The presence of loose bodies in knee joint
  • Osteophytes of the joint
  • Synovial hypertrophy (by synovectomy)
• Osteochondral allograft (bulk or mosaic)
• Arthrodesis (Fusion)

References

• John Crawford Adams and David L.Hamblen. Outline of Orthopaedics. Twelfth Edition. ISBN 0 443 05149 6
• Darlene Hertling and Randolph M.Kessler. Management of Common Musculoskeletal Disorders. Third Edition. ISBN 0-397-55150-9