A little prediction

A week ago Mortensen et al. published a study protocol investigating medial unicompartmental versus total knee arthroplasty for anteromedial tibio-femoral osteoarthritis.

This study setting is very interesting. Both total knee replacement (TKR) and unicompartmental knee replacement (UKR) can be used to treat medial sided knee osteoarthritis. Mortensen et al. nicely sum up both pros and cons of TKR and UKR:

From Mortensen et al. (2019)

This is not, however, first of it´s kind study. As stated by Mortensen et al., several other RCTs on the topic are being carried. So, in few years, we will have at least a few high quality studies comparing UKR and TKR.

I am quite sure how things will sort out and how the orthopedic community will act and hence I wish to make a little (pessimistic) prediction.

I guess that the results of RCTs will be in line with the pros & cons above. In short, UKR will result to faster recovery and this is will be the cost of higher revision risk in short term. And for TKR, it is contrary. I also guess that once few RCTs are available, we will see endless “debates” and “discussion forums” where proponents and advocates of either technique will discuss and selectively use the results from these RCTs.

My main point is that the case of TKR vs UKR will be an excellent platform for shared decision making. I hope that the community will not engage on futile debates on superiority of either technique. Both of them have their pros and cons and superiority can not be established. Instead, when deciding between UKR and TKR in patient with medial knee OA, one should acknowledge patient preferences and incorporate them into a patient specific utility function, maximize it and make a shared decision. This of course sounds over-optimistic, not at least owing to the fact that currently we do not have any solid framework for these “utility functions”. Simpler approach for now includes a thorough discussion with our patients stating all pros and cons for both techniques and aiming to achieve an informed and shared decision obeying the values and preference of the patient.

I will return to this topic once the RCTs are being published!


Mortensen et al. Randomized clinical trial of medial unicompartmentel versus total knee arthroplasty for anteromedial tibio-femoral osteoarthritis. The study-protocol. BMC Musculoskelet Disord. 2019 Mar 20;20(1):119. doi: 10.1186/s12891-019-2508-1.

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