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According to the AOA National Joint Replacement Registry, the best knee replacement design choice has a 60% reduction in revisions, but it only used by 9% of surgeons.

In October 2018 – The Australian Knee Society held it’s Annual Scientific Meeting.  Chris Vertullo from the National Joint Replacement Registry presented a concept that not all surgeons make rational decisions from the AOA NJRR. The low risk implant is: Cruciate retaining, cemented tibia, with patella resurfacing, highly cross linked polyethylene, and fixed (not mobile) bearing.  The re-operation rate at 10 years for this combination is 2.4%, contrasting 5.5% for combined results of alternate designs, i.e. a 60% reduction in the risk of requiring revision surgery.  This is based on a 482,373 knee replacements performed in Australia.

A difficulty has been that each individual factor has only a marginal change to results, and hard to prove. Patella resurfacing has been difficult to prove that it improves results.  But – there is a marginal decrease in re-operation if it is done at the primary operation.  The Australian incidence of patella resurfacing is now gradually increased from 41% in 2003 to 64% in 2016. How implants are fixed to the has changed in the same period from 74% to now 89% where surgeons only trust bone cement to permanently bond the tibia to the metal.  The other difficulty is an individual surgeon’s figures aren’t the same as averaged data, and patient satisfaction isn’t measured in the registry.

Not discussed was what to do with younger patients with arthritis.  Where possible, joint replacement should be avoided with weight reduction and other non operative managements, osteotomies, and sometimes partial knee replacement.  The 10 year revision rate for TKR is 13% for men under 55, vs 8% for men 55-65, so picking a surgeon prepared to discuss all options is wise!

Mr David Mitchell

 

Refs:

Vertullo CJ, Graves SE, Peng Y, Lewis PL. An optimum prosthesis combination of low-risk total knee arthroplasty options in all five primary categories of design results in a 60% reduction in revision risk: a registry analysis of 482,373 prostheses. Knee Surg Sports Traumatol Arthrosc. 2018 Aug 20. doi: 10.1007/s00167-018-5115-z. [Epub ahead of print]

Pilling RW et al, Patella resurfacing in primary total knee replacement: a met-analysis. JBJS(Am) 2012, 94(24):2270-8
Pavlou G, Patellar resurfacing in total knee arthroplasty: does design matter? A meta-analysis of 7075 cases. JBJS(Am) 2011, 93(14):1301-9

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