Knee Arthrotomy and Washout

Capsule of the right knee joint, distended, lateral view
Capsule of the right knee joint (distended), lateral aspect. Image by Henry Gray (Anatomy of the Human Body, 1918), Wikimedia Commons, Public domain.

Indications

  • Septic arthritis of the native knee with failed arthroscopic or needle lavage.
  • Loculated collections, thick fibrinous debris or delayed presentation.
  • Gächter stage IV infection with pannus, cartilage erosion or radiographic change.
  • Adjacent osteomyelitis needing drainage.
  • Arthroscopic lavage suits earlier Gächter stages I to III.

Position

  • Supine with a thigh tourniquet.
  • Elevate the limb to exsanguinate. Avoid an Esmarch bandage over infected tissue.
  • Aspirate and send fluid for culture before antibiotics when the patient is stable.

Operative Steps

  1. Make a midline longitudinal skin incision centred on the patella.
  2. Perform a medial parapatellar arthrotomy, leaving a retinacular cuff on the patella for closure.
  3. Subluxate or evert the patella and flex the knee to inspect the joint.
  4. Send fluid and synovium for Gram stain, culture, crystals and histology.
  5. Debride fibrin and loculations and perform synovectomy of the suprapatellar pouch, both gutters and the intercondylar notch.
  6. Inspect cartilage and menisci, and debride devitalised tissue.
  7. Irrigate with several litres of warm saline.
  8. Place a closed suction drain and close the arthrotomy loosely, then the skin.

Postoperative Care

  • Start empirical intravenous antibiotics after samples, then tailor to culture and infectious diseases advice.
  • Remove the drain at 24 to 48 hours.
  • Repeat the washout if fever, pain or CRP fail to settle.
  • Start early active and passive knee motion to protect cartilage and limit stiffness.

Complications

  • Persistent infection needing staged repeat lavage.
  • Osteomyelitis of the femoral condyle or proximal tibia.
  • Chondrolysis and post-septic arthritis.
  • Arthrofibrosis and quadriceps weakness.
  • Infrapatellar branch of the saphenous nerve neuroma.
  • Wound dehiscence or sinus formation.
  • Venous thromboembolism.

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 20 October 2026.