Although obesity has often been considered to be a contraindication to fixed bearing UKA, we have never considered it to be a contraindication for OUKA. Studies of retrieved meniscal bearings have revealed no association between patient weight and linear wear rate (Murray et al., 2013).
We studied the effect of BMI on outcome in a two centre series of 2467 patients followed up to 12 years. It was found that there was no significant difference in survival with patients of different BMI (Murray et al., 2013). In fact in the 80 super-obese patients with BMI >45, there were no failures. The final OKS did decrease with increasing BMI. However, because the preoperative OKS decreased with increasing BMI, the improvement in OKS actually increased with increasing BMI. We therefore do not consider high BMI to be a contraindication. Indeed, in patients with high BMI, we prefer to implant the OUKA rather than a TKA because the surgery is much simpler. The instrumentation works from the front and the extensor mechanism only needs to be subluxed laterally and not everted or dislocated as in TKA.
