Knee pain

Differential diagnosis

  • Septic joint – fever, systemically unwell, red, swollen
  • Osteoarthritis – wear and tear of joint – gradual onset of pain, stiffness, reduced ROM, crepitus
  • Meniscal injury- sudden twisting, locking, recurrent effusion after activity, moderate effusion within 36 hours
  • Ligament injury
    • popping at time of injury, knee gives way, large and tense effusion within 2 hours
    • Mechanism:
      • Anterior cruciate ligament injury – sharp turns and sudden stops or hyperextension
      • Posterior cruciate ligament injury – blow to anterior aspect of knee while in flexion (in RTA where knee hits dashboard)
      • Medial collateral ligament – blow to lateral aspect of knee
      • Lateral collateral ligament – blow to medial aspect of knee (more common)
  • Patellar tendonitis – pain over patella often from repetitive overloading e.g jumping – knee swelling, patellar tenderness
  • Chondro-malacia patella – young girl, anterior knee pain worse on stairs – crepitus, fluid behind knee
  • Osgood-Schlatter’s – teenage boys, pain and swelling below knee
  • Baker’s cyst – fluid filled swelling that develops at the back of the knee – pain, swelling, locking

 

Data gathering

  • Red flag – fever, systemically unwell
  • Others – locking, giving way, trauma, swelling (timing of swelling), rest pain
  • Examine
    • Look – symmetry, wasting, swelling, redness
    • Feel – temperature, joint line, patella tenderness
    • Move – flexion, extension, cruciate and collateral ligaments

 

Clinical management

  • Investigations
    • Xray – if degenerative change suspected
    • MRI – if likely result can be managed in community
  • Treatment
    • Septic arthritis
      • Refer to orthopaedics same day
    •  OA
      • see OA
    • Meniscal problem
      • analgesia, rest, surgery (for larger tears)
    • Ligamentous injury
      • analgesia, rest, physiotherapy, surgery
    • Patellar tendonitis
      • analgesia, rest, knee exercises, steroid injection
    • Chondro-malacia patellae
      • avoid repetitive knee bending, rest, analgesia, knee supports, surgery
    • Osgood-Schlatter’s
      • analgesia, ice, knee support, reduce strenuous activity, knee support, physiotherapy
    • Baker’s cyst
      • Tx: self limiting, analgesia, RICE, surgery
  • Follow-up / Safety-net
    • Consider referral
      • Red flags
      • Joint instability
      • Severe pain
      • Surgery indicated

Nb:

  • Knee exercises – sit/stand without hands, knee squats