Am I Fit for Surgery? Pre-operative Optimisation

Part of The Joint Replacement Guide — Phase 2: Considering Surgery · Article 10 of 42 · Hip & Knee

Key Points

  • “Fitness for surgery” is about a combination of factors, and many of the most important ones can be improved before your operation.
  • Weight, blood sugar control, smoking, and anaemia are among the biggest modifiable risk factors.
  • Optimisation is about making your surgery as safe as possible — not about finding reasons to deny it.
  • Both your GP and the pre-assessment clinic play a role in this process.

Why Optimisation Matters

Every operation carries some risk, and a number of health and lifestyle factors influence how large that risk is — particularly the risk of infection, poor wound healing, and cardiac or respiratory complications around the time of surgery. Many of these factors are modifiable, meaning there is real, evidence-based benefit to addressing them in the weeks or months before your operation, rather than simply accepting them as fixed. This process is usually called pre-operative optimisation, and it typically runs in parallel with, or slightly ahead of, the prehabilitation exercise programme covered in the next article.

Weight

Higher body weight is associated with an increased risk of wound complications, infection, and technical difficulty during surgery, and many units use local guidance around BMI when planning elective joint replacement — this varies between hospitals, so it’s worth asking your own team what applies to you. Importantly, this is approached as a genuine, individualised discussion and a modifiable factor to work on, not an automatic barrier — the weight management approaches covered earlier in this guide are directly relevant here.

Blood Sugar Control

If you have diabetes, well-controlled blood sugar in the run-up to surgery meaningfully reduces the risk of wound and joint infection. Many units use a target HbA1c (a measure of average blood sugar control over the preceding weeks) as part of pre-operative assessment, and your GP or diabetes team may be involved in helping you reach this before your surgery date is confirmed. This is one of the most evidence-backed of all the modifiable risk factors in joint replacement surgery.

Smoking

Stopping smoking before surgery reduces the risk of wound complications, chest infections, and slower bone and wound healing. Even stopping a relatively short time before your operation — a few weeks — provides measurable benefit, though the earlier you can stop, the better. Free NHS smoking cessation support is available and is generally the most effective route to quitting successfully before surgery.

Anaemia and Nutrition

Pre-operative anaemia (low blood count) is now routinely screened for and, where found, treated before surgery — this reduces the likelihood of needing a blood transfusion and is associated with a smoother recovery. General nutritional status also matters for wound healing, so eating well in the weeks before surgery, rather than only afterwards, is genuinely worthwhile.

Dental Health

This one surprises many patients: active dental infection is a recognised potential source of bacteria that can travel through the bloodstream and seed a new joint implant, which is why a dental check-up is often recommended before major joint replacement surgery, particularly if you haven’t seen a dentist recently or have known dental problems.

In More Depth

National perioperative care guidance frames these modifiable factors — weight, smoking, blood sugar, anaemia and general fitness — as a structured “optimisation window” between referral and surgery, during which meaningful risk reduction is achievable for most patients. This is distinct from non-modifiable factors, such as age or certain underlying health conditions, which cannot be changed but are still carefully accounted for in surgical and anaesthetic planning — for example, in the choice of anaesthetic technique, covered in a later article on anaesthetic risks. The pre-assessment clinic, which you will usually attend in the weeks before surgery, exists specifically to review all of these factors together, run any necessary tests, and confirm you are ready to proceed safely.

This article is general information and does not replace individual clinical advice. Specific targets and thresholds vary between hospitals — please discuss what applies to you with your own team.

Sources

  • Centre for Perioperative Care (CPOC) — guidelines for perioperative care and optimisation
  • NICE guideline NG157 — Joint replacement (primary): hip, knee and shoulder (2020)
  • Royal College of Anaesthetists — pre-operative assessment guidance
  • NHS.uk — smoking cessation and diabetes pre-operative care resources

← Back to the Joint Replacement Guide · Previous: Your Role, Your Family’s Role, Your Team’s Role · Next: Pre-habilitation — Getting Stronger Before Surgery