Overview of Knee Pain

Contents

Knee pain accounts for about 1 in 50 general practice presentations – and is thus a very common presentation.

Swelling that occurs within 30 minutes of an injury is typically haemarthosis
- This is more commonly associated with ACL injuries
Swelling that occurs over a period of days is typically synovial fluids / effusion
Any red, warm swollen joint is septic arthritis until proven otherwise

Collateral ligament tears require prompt surgical treatment
Other ligament injuries – such as ACL and PCL, as well as meniscal injuries are not so time-critical
Twisting injuries tend to cause meniscal injuries
Lateral force injuries tend to cause cruciate ligament and collateral ligament injuries

Patellofemoral syndrome
- The most common cause of knee pain
- Typically an overuse injury
- A bit of a “catch-all” term for minor ligament and muscle strains – which are usually benign and self-limiting
- Previously known as “chonromalacia patellae”
Injury
- ACL
- PCL
- Collateral ligaments
- Meniscal tear
- Tibial plateau fracture
- Patella fracture
- Patella dislocation
Infection
- Septic arthritis
Rheumatological disorder
- Gout
- Pseudogout
Referred hip pain
Referred neuropathic pain (L3 – S1)
Osteoarthritis
DVT
- and ruptured Baker’s cyst
Cancer (primary or metastatic)
Paediatrics
- Osgood-Schlatter disease
- Perthes disease
- Slipped capital femoral epiphysis (referred from hip)
- Septic arthritis

Ottowa knee rules – for indication for x-ray – if ANY of the following are present, x-ray is indicated:
- Unable to weight bear
  - Cannot take 4 or more steps
- Aged >55
- Tenderness at head of fibula
- Inability to flex to 90 degrees
MRI
- May be indicated if any evidence of ligaments or meniscal injury
- Typically as an outpatient procedure (unlikely to be indicated in Emergency Department)
Knee aspiration
- Indicated in any red, warm, swollen knee
- To assess for septic arthritis (and gout)