Arthritis UK has called on the NHS to scrap BMI threshold policies used to ration surgeries. YKC’s Nick London agrees.

In an ideal world, every patient would arrive for knee surgery in good health, good condition and with an optimised body mass index (BMI – used for calculating healthy weights).

There’s good reason for wanting that. A lower BMI means a lower risk of complications during operations and a greater likelihood of longevity for a patient’s knee implant. More generally, lower BMIs indicate a reduced risk of high blood pressure, heart disease, type-2 diabetes and other chronic diseases.

So, for as long as I can remember, knee surgeons have encouraged patients with less-than-ideal BMIs to lose weight before surgery and to try and keep that weight off afterwards.

That word “encouraged” is important.

> Discover more about partial knee replacements
> Weight loss drugs and osteoarthritis – is there a benefit?

BMI shouldn’t be a barrier to knee surgery

Arthritis UK neatly sums up the issue: “Recent findings reveal that almost a fifth of ICBs in England [that is, care boards responsible for planning local health services] are ignoring NICE guidelines by rationing surgeries based on a person’s BMI without conducting proper individual assessment.”

So rather than encouraging weight loss ahead of surgery, the position instead – in some areas of the country – is no surgery without weight loss.

As Arthritis UK notes, this can lead to “avoidable suffering, prolonging pain and joint deterioration”. It compounds health inequalities. That’s why Arthritis UK has called on ICBs to scrap BMI threshold policies used to ration surgeries.

A duty to provide care

I absolutely agree with the sentiment of Arthritis UK’s statement. My view is if that if the patient is young, we have a combined duty (patient and health authority) to help them optimise their BMI prior to surgery as much as possible because there’s no doubt that partial and total knee implants are more likely to last longer when your BMI is lower. In a younger patient, locking in that longevity is important because treatment options become increasingly limited as implants wear over decades.

There’s no escaping the fact, though, that for many patients – and particularly older patients – it’s very difficult for them to lose weight when crippled with arthritis. For any patient trying but failing to lose weight and facing a downward spiral of pain, joint deterioration and increased immobility, it’s cruel to deny treatment. It’s especially cruel for older patients (i.e. 65+).

The NHS has a duty to provide care. While it may be the case that patients with an increased BMI will on average have a slightly higher implant revision rate – that is, they’ll need to have their surgery redone later in life – this is a relatively small number. For over 65s, a group that is typically less active than their younger counterparts, this is unlikely to have a significant impact on how long their implant lasts.

Not just BMI

Recently, of course, it has become somewhat easier for patients to lose weight. Thanks to the explosion in medications such as Wegovy and Ozempic, we are seeing many more patients able to reduce their BMI.

Even here, though, we need to be careful about relying on BMI as an indicator of surgical readiness. Someone who has rapidly reduced their BMI thanks to injections is not necessarily healthy. We’re still in an uncertain period with weight loss treatments, but it does seem wise to ensure that patients arrive at surgery well nourished and in good condition, because this will support their recovery and healing. So, having reduced weight using medication, patients need a period of stability in which they can recover and reach a good nutritional state for surgery.

> Weight loss drugs and osteoarthritis – is there a benefit?

High BMI no barrier to excellent outcomes

In 2021, we launched a study of partial knee resurfacing patients to explore long-term outcomes and satisfaction. Now, we’ve published the five-year results (you can find the paper here). It’s worth noting the findings with regard to one subset of patients with a BMI over 40 (classed as severely obese). They reported excellent implant satisfaction and outcomes.

We encourage them to lose weight post surgery, but this is further evidence, I believe, that BMI should not be a barrier to that surgery in the first place.

Is it time for knee replacement surgery? Please get in touch or phone us on 03453 052 579.

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