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KneeFurther Opinion

Unnecessary contraindications for mobile-bearing unicompartmental knee replacement

H. Pandit, C. Jenkins, H-S. Gill, G. Smith, A. J. Price, C. A. F. Dodd, D. W. Murray

J Bone Joint Surg [Br] 2011;93-B:622-8.

 

This paper from the Oxford group is timely because of the continuing controversy with regard to indications for medial unicompartmental knee replacement.

For many years the Kozinn and Scott paper of 1989 has been used as a guide to indications for surgery.  Those contraindications have been considered very restricting, with the result that using their criteria only about 1 in 20 arthritic knees would be deemed appropriate for unicompartmental replacement.  It is also relevant to note that the reported implant is no longer in regular use and was a fixed bearing implant with a polyradial femur.

This paper carries a great weight of numbers (1000 implants were prospectively reviewed).  The authors present convincing evidence to suggest that the excessive weight, age under 60 and high activity levels do not appear to influence the results to any significant degree and therefore should not be considered as contraindications.

They also support the original suggestion made by Woods et al in 1995 that chondrocalcinosis can be ignored.

Perhaps the most contentious of all is the issue of the patello-femoral joint.  Despite continuing concerns on the part of knee arthroplasty surgeons world wide from the Oxford school have consistently stated that the patello-femoral joint can be largely ignored in assessing patients for medial tibio-femoral unicompartmental replacement and the various national joint registries have tended to support that view.  This large study supports the Oxford view that exposed bone in the patello-femoral joint should not be considered as a contraindication although one would have to add a rider here “when using the Oxford mobile bearing implant”.  This suggestion was acknowledged in their conclusion.

I believe this is an important publication which fully supports the original Oxford criteria when using mobile bearing Unicompartmental implants and the numbers gives added emphasis.

 

Malcolm Glasgow

Norfolk and Norwich University Hospital

Norwich, UK

Email: Glenda.Marjoram@nnuh.nhs.uk