Knee Replacement

knee xray

What is it?

Knee arthroplasty, or replacement, is a surgery where the knee joint is either fully or partially replaced. This is done by removing the diseased sections of the bone and replacing them with prosthetic implants. In the UK alone, over 70,000 knee replacements happen each year with primarily more women than men have this surgery. The average ages of patients that have this surgery are 70 years old.

Knee Replacement

What patients are suitable for a knee replacement?

 Patients with end stage osteoarthritis or a form of inflammatory arthritis are the most likely to be eligible. Inflammatory arthritis includes rheumatoid or septic causes. Arthritis is where the smooth cartilage lining the bones in the knee has degraded due to injury or infections, which causes swelling in the joint and formation of bony spurs called osteophytes. When this is severe, this can cause bone-on-bone rubbing. Those patients with severe pain and/or disability at the knee will also be indicated.

Partial (half) vs total replacement

 Depending on the amount of disease seen, the surgeon may decide to perform a partial or total knee replacement. This will depend on how many compartments of the knee are affected. There a three compartments: medial (inside), lateral (outside) and patella-femoral (knee cap-thigh bone interface). If more than one compartment is affected, it’s likely the surgeon will perform a full knee replacement. A partial knee replacement has been shown to have better functional outcomes in some studies however patients are more likely to need a second surgery later in life. A partial knee replacement lasts an average of 10 years, whereas a total knee replacement can lasted over 20 years for some patients.


What to do after surgery?

Rehabilitation will be the most effective for improving function following surgery. Your physiotherapist may follow a particular protocol, such as the one below.

Day 1-3 post operation

  • Taught how to walk with crutches
  • Gentle exercises to improve knee movement
  • Blood clot prevention exercises
  • Reduction of swelling

Week 1-2

  • Gaining normal knee movement
  • Improving knee and hip strength
  • Reduction of swelling

Week 3-6

  • More intense knee movement exercises
  • Leg strengthening exercises
  • Improvement of walking ability and weaning from crutches
  • Control of swelling
  • Improvement of balance

Week 7+

  • Leg strengthening, maximising functional ability
  • More advanced balance exercises
  • Return to normal activities such as driving and work

Some patient’s progress will be faster and slower than this as everyone is individual. Your physiotherapist will guide you through this process and progress you at the rate appropriate for you. Ongoing physiotherapy may be recommended for some patients as they return to activities of daily living.


Carr, A. J., Robertsson, O., Graves, S., Price, A. J., Arden, N, K., Judge, A. & Beard, D. J. (2012). Knee Replacement. The Lancet, 379 (9823). pp. 1331-1340.  

NHS (2018). Arthritis. Online. URL: [Last Accessed 18/11/19].

Oatis, C. A., Li, W., DiRusso, J. M., Hoover, M. J., Johnston, K. K., Butz, M. K., Phillips, A. L., Nanovic, K. M., Cummings, E. C., Rosal, M. C., Ayers, D. C. & Franklin, P. D. (2014). Variations in Delivery and Exercise Content of Physical Therapy Rehabilitation Following Total Knee Replacement Surgery: A Cross-Sectional Observation Study. International journal of physical medicine and rehabilitation, s5 (2).

Ranawat, C. S., Ranawat, A. S. & Mehta, A. (2003). Total knee arthroplasty rehabilitation protocol: What makes the difference? The journal of arthroplasty, 18 (3). S1. pp. 27-30. 

Sears, B. (2019). Rehabilitation protocol after a total knee replacement. Online. (Date: 02/11/19). URL: [Last Accessed 19/11/19]. 

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