Osteoarthritis of knee
Classic history and presentation: Patients often present due to long-standing pain and stiffness in one or more joints. Further examination can reveal crepitus, bony enlargement or osteophyte formation, joint effusion, and point tenderness. Classically, the patient will have joint pain that worsens with activity, as opposed to an inflammatory arthritis that will improve with activity. Imaging is often used to diagnose the extent of joint arthritis and follow the joint's degenerative progression.
Prevalence: About one-third of people older than 65 years have knee osteoarthritis, so this disease has a very high prevalence among the general population. Recent estimates have shown that the prevalence will only increase, due to more people becoming overweight and obese.
Risk factors: There are many risk factors for knee osteoarthritis, including female sex (45% increased risk for women compared to men), older age, genetics, overweight or obese body mass index (BMI), previous joint injury / trauma (eg, intra-articular fracture, ligamentous injury, meniscal injury), joint malalignment, and repetitive joint damage.
M17.9 – Osteoarthritis of knee, unspecified
239873007 – Osteoarthritis of knee
- Septic arthritis – Suspect if the joint is erythematous and/or warm with overlying erythema, painful motion, and systemic signs of illness. Medical comorbidities increase the risk of joint infection (eg, history of intravenous drug use, uncontrolled diabetes mellitus type 2).
- Inflammatory arthritis (rheumatoid arthritis, psoriatic arthritis) – Suspect with multijoint involvement and when x-ray imaging shows bony erosions.
- Meniscal tear – MRI imaging is used to rule this out.
- Ligamentous injury – Anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL). MRI imaging is used to rule this out.
- Bone contusion
- Osteochondral defect / lesion
- Pes anserine bursitis
- Patellofemoral pain syndrome
- Crystal arthropathy – See gout and calcium pyrophosphate deposition disease.
- Lyme disease
- Pigmented villonodular synovitis (PVNS)
- Cancer – Metastatic lesion versus primary sarcoma.