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All topics
  1. What it is
  2. Who it helps
  3. Timing
  4. The procedure
  5. Patient journey
  6. Recovery supplies
  7. Implant designs
  8. Side-by-side
  9. Robotics and alignment
  10. US manufacturers
  11. What the evidence says
  12. Value analysis
  13. Questions to ask
  14. Resources
  15. Glossary
  16. References

How

The procedure, step by step

Details vary by surgeon and hospital, but most knee replacements follow the same general path. The operation itself usually takes about 1 to 2 hours.46,50

  1. Evaluation and planningX-rays show how much arthritis there is and how the leg is aligned. Some systems also use a CT scan or MRI before surgery, for robotic planning or for custom cutting guides or implants.
  2. AnesthesiaMany patients have a spinal anesthetic, often with a nerve block for pain relief; others have general anesthesia. Your anesthesia team will explain the options.
  3. The incisionThe surgeon makes an incision over the front of the knee and moves the kneecap aside to reach the joint.
  4. Preparing the boneWorn cartilage and a thin layer of bone are removed from the ends of the thighbone and shinbone, using cutting guides, navigation or a robotic system to set the angles.
  5. Trial and balanceTrial components are fitted and the knee is moved through its range. The surgeon checks alignment and balances the soft tissues so the knee is stable in both bending and straightening.
  6. Fixing the implantThe final components are fixed to the bone, either with bone cement or by press-fit into a porous surface that the bone grows into (cementless). The plastic spacer is locked in place, and the kneecap may be resurfaced.
  7. Closing and recoveryThe incision is closed and dressed. Many hospitals get patients standing with a walker the same day. Some people go home that day; most go home after one night.45,49
Clinical detail
  • Design decisions made in surgery include cemented vs cementless fixation, cruciate-retaining vs posterior-stabilized or medial-congruent bearings, and whether to resurface the patella. See implant designs.
  • Technology-assisted options (navigation, robotics, patient-specific guides) and alignment philosophy are covered in robotics and alignment.
Value analysis

Robotic systems and patient-specific guides can add pre-operative imaging, capital or per-case costs, and set-up time. Same-day pathways shift care from the inpatient stay to home and outpatient therapy. See value analysis.

Sources for this page

  1. American Academy of Orthopaedic Surgeons, OrthoInfo. Total knee replacement. orthoinfo.org/treatment/total-knee-replacement
  2. Mayo Clinic. Knee replacement. mayoclinic.org/tests-procedures/knee-replacement
  3. Hospital for Special Surgery. 6 things to know about recovery after knee replacement. hss.edu/health-library/move-better/knee-replacement-recovery
  4. MedlinePlus (US National Library of Medicine). Knee joint replacement. medlineplus.gov/ency/article/002974.htm

All references