It is claimed 16% of knee replacements patients aren’t that impressed with their outcome – I’d be devastated if that’s what we saw at Ballarat Orthopaedics & Sports Medicine. Metal allergy probably contributes to this percentage.

Maybe 5% of people can’t tolerate nickel – be it in cheap earrings, or stainless steel watches. Nickel turns out to be a common impurity in chrome-cobalt alloys used for the femoral component of knee replacements. To its credit – that alloy is hard to scratch, easy to coat the surface rubbing against the femur with titanium which helps bone ongrowth.

Titanium is a rare allergy – used in the tibial component of most knee replacements, but is too soft to use as a bearing surface for the femoral component, it scratches too easily. Most low allergy knee replacements – for example the Persona Titanium/Niobium coated implant (Zimmer-Biomet), or the Oxiniuim coated Journey knee (Smith & Nephew) both have titanium tibial baseplates. Whilst all polyethylene tibial components exist – most surgeons are avoiding them in younger patients.

B.Braun Columbus offers a multiply coated implant – both femur and tibia components. Admittedly there is still the question of cement allergy. At the end of the day – we have a case by case solution. Routine testing for allergies has not been demonstrated to improve outcomes, but where someone seems to be at risk, we’re keen to have a solution.