Many hospitals apply a Body Mass Index (BMI) cut-off — most commonly 40 — as a threshold for joint replacement. The intention is to reduce surgical risk, which is genuinely higher at a higher BMI. In practice, though, it can mean people are declined without a thorough individual assessment or a clear way forward — often caught in a cycle where joint pain makes the exercise needed to lose weight feel impossible. Dr Yas does not start from "no". He assesses each person individually, is honest about the elevated risks, and where surgery is appropriate, plans carefully to make it as safe as possible.
The cycle you may be in
Perhaps you have been told that surgery is not an option until you lose weight. Perhaps you have been trying to do exactly that, only to find the joint pain makes exercise feel impossible. Perhaps you feel stuck — unable to move freely because of your joints, and unable to access the treatment that could help because of your weight.
If that sounds familiar, please know this is not a personal failing. Osteoarthritis and obesity are complex medical conditions with overlapping causes, and surgery may actually be part of breaking the cycle.
Where the BMI cut-off comes from
Many public and private hospitals across Australia apply a BMI cut-off, most commonly set at 40, as a threshold for joint replacement surgery. The intention is reasonable: surgical complications are known to be higher at a higher BMI, and the policy aims to reduce them.
The difficulty is that, in practice, people with a BMI above the cut-off are frequently declined — sometimes without a thorough individual assessment, and without a clear pathway forward. A single number ends up deciding, rather than the whole picture.
An individual assessment, not a number
Dr Yas takes a patient-first, whole-person approach. Rather than reading your BMI alone, he assesses your joint imaging and mobility, your muscle strength and activity level, your full medical history and cardiovascular health, and your personal goals and recovery expectations.
Suitability for surgery is always determined individually, after a thorough clinical assessment — with dignity and without judgement.
Making surgery as safe as possible
Where surgery is appropriate, careful preparation matters. That can include optimising your general health and any medical conditions before the day, three-dimensional planning, considered surgical technique, and robotic technology to help address difficult anatomy accurately.
Dr Yas is honest about the elevated risks that come with a higher BMI, and works with you to reduce them — so any decision is made with a clear understanding, never a promise of a particular outcome.
What supports going ahead, even at a higher BMI
After an individual assessment, the factors that generally support further consideration of surgery include: severe daily osteoarthritis pain confirmed on imaging that has not settled with non-operative treatment (physiotherapy, weight management and pain management); medical conditions such as diabetes, blood pressure or sleep apnoea that are well controlled and reviewed by your GP or specialist; no active medical reasons that would make anaesthesia or surgery unsafe; and a clear understanding of the higher risks, with a willingness to engage in preparation beforehand.
This is general information, not a decision — your own pathway is confirmed at consultation.
Key takeaways
Common questions
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Been told you’re too young, too heavy, or to just wait?
Dr Yas reviews each patient case by case and recommends the operation that fits the joint — not the other way around. Higher-BMI patients considered on their individual merits, not declined on weight alone.
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Specialist revision hip & knee surgery, partial-to-total conversion with modern bone-preserving technique, and complex reconstruction after trauma — including limb-preserving surgery — considered case-by-case.
Latest insights from Dr Yas
Plain-language articles on modern hip & knee surgery — written to help you make an informed decision.
- Kerkhoffs GMMJ, Servien E, Dunn W, Dahm D, Bramer JAM, Haverkamp D. The influence of obesity on the complication rate and outcome of total knee arthroplasty: a meta-analysis and systematic literature review. Journal of Bone and Joint Surgery (American). 2012;94(20):1839–1844.
- American Academy of Orthopaedic Surgeons (AAOS). Knee Replacement — patient information. OrthoInfo; reviewed 2023. orthoinfo.aaos.org