Knee Replacement Surgery – Partial v Total

The National Joint Replacement Registry has been tracking the performance of hip and knee replacements inserted since 1999. In October 2013, they reported that more than 800,000 Australians have a joint replacement and each year another 90,000 devices are inserted at a cost of around 1 billion dollars.


The most common cause of chronic knee pain and disability, increasing the potential need for surgical intervention is arthritis. Generally, this can be categorised into 3 main types:
• Osteoarthritis: age-related wear and tear which may lead to ‘bone on bone’, with a usual onset > 50 years of age, however may occur earlier
• Rheumatoid arthritis: Inflammation or thickening of the synovial membrane that surrounding the joint, leading to cartilage loss
• Post-traumatic arthritis: developing post injury
– E.g. Fractures of knee/ bones surrounding the knee, or torn ligaments


The Australian Orthopaedic Association, National Joint Replacement Registry 2014 Annual Report (Hip and Knee Replacement) acknowledges three different categories of knee replacement, these being: primary partial, primary total and revision knee replacement.


Recent Statistics:
• There were 51,212 knee replacements undertaken and reported to the Registry in 2013. This is an increase of 3.4% compared to the number reported in 2012
• Primary partial knee replacement accounts for 9.2% of all knee replacements reported to the Registry since it commenced data collection
• Primary total knees account for 82.5% and revision knees 8.3%
• In 2013, there was a 77.2% increase in the number of knee replacements compared to 2003
– Primary total knee replacement has increased by 101.6% since 2003
– Revision has increased by 73.8%
– Primary partial knees however have decreased by 45.4%


The National Joint Replacement Registry identifies five classes of primary partial knee replacements, with the most used partial knee replacement being the unicompartmental knee (accounting for 93.4% of all primary partial knee replacements).


The goal of any knee replacement surgery is to decrease pain and restore function. In a unicompartmental knee replacement, only the damaged compartment is replaced with metal and plastic. The healthy cartilage and bone in the rest of the knee is left alone.


Partial v Total
• Less invasive incision
• Less time spent in hospital
• Less pain/ swelling after surgery
• Less blood loss
• Patient self- report of feeling more ‘natural’
• Greater knee flexion
• Quicker recovery/ return to usual activity and work


• Less predictable pain relief
• Potential need for more surgery.
– E.g. A total knee replacement may be necessary in the future if arthritis develops in the parts of the knee that have not been replaced.


In line with the disadvantages listed above, the National Joint Replacement Registry 2014 Annual Report found that unicompartmental knee replacements had a higher rate of revision than primary total knee replacement. Further to this, primary total knee replacement was found to have the lowest rate of revision compared to all other types of primary knee replacement. Important to note however, was that the rate/ trends of revision generally declines as patients get older and in patients aged over 75 years there is only a 3.1% chance they will have a revision within the first 13 years.


The staff at Workplace Physiotherapy have significant experience in the delivery of prehab (rehab prior to surgery) and post-operative rehabilitation following joint replacement.






The comments above are the implicit advice of Workplace Physiotherapy. The views expressed are based on current evidence-based research and accepted best practice approaches. Unless otherwise stated, these comments are not the view of WorkCover NSW or any other professional body. No reproduction or forwarding of this advice is permitted without the consent of the author.


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