Modifiable Risk Factors & Risk Stratification
- The modern paradigm is OPTIMIZATION (actively improving modifiable risk), not passive 'medical clearance'.
- Key modifiable factors: obesity, malnutrition/hypoalbuminaemia, diabetes, anaemia, smoking, opioid use, and Staph aureus carriage.
- Hypoalbuminaemia (serum albumin less than 3.5 g/dL) flags malnutrition and predicts infection and complications.
- Poor glycaemic control (elevated HbA1c / perioperative hyperglycaemia) increases prosthetic joint infection risk.
- Smoking cessation and pre-operative anaemia correction measurably reduce complications and transfusion.
- The overarching goal is to reduce prosthetic joint infection and other complications of this elective operation.
- “Frame the answer as a structured, system-based optimization checklist, not a list of 'bloods'.
- “Stress that this is ELECTIVE surgery - there is time to optimise, and deferring to optimise is legitimate.
- “Name albumin as the single most useful nutrition marker and Staph decolonisation as a cheap, high-yield intervention.
A binary sign-off - "fit / not fit for anaesthesia." It is passive, treats risk as fixed, and misses the opportunity to actually lower the patient's risk before an elective operation.
Actively identify and improve modifiable risk factors (glycaemia, nutrition, anaemia, smoking, weight, Staph carriage) before surgery. Because arthroplasty is elective, surgery can be deferred until the patient is in the best achievable state - measurably reducing complications.
Overview
Hip and knee arthroplasty are highly successful but elective procedures, so the threshold for accepting preventable risk is low. Many of the strongest predictors of complications - particularly prosthetic joint infection (PJI) - are modifiable. Pre-operative optimization systematically identifies and improves these factors, shifting care from a one-off "clearance" sign-off to an active risk-reduction programme.
The case for optimization is strongest for PJI, the most feared complication, which is devastating and costly and whose risk is concentrated in patients with controllable comorbidities. The same factors also drive wound complications, transfusion, medical complications, readmission and mortality. The surgeon's role is to screen, to set evidence-based targets, to coordinate optimization with primary care and relevant specialists, and - crucially - to be willing to delay elective surgery until modifiable risk is improved.
The Modifiable Risk Factors
Obesity, Diabetes & Nutrition
- Obesity: A high BMI is associated with more wound and infection complications and technical difficulty. Where feasible, supported weight optimization before surgery is reasonable; very high BMI thresholds for proceeding remain debated and should be individualised rather than applied as rigid cut-offs.
- Diabetes / glycaemic control: Poor glycaemic control (elevated HbA1c and perioperative hyperglycaemia) is consistently linked to increased PJI. Aim to improve glycaemic control before elective surgery and to control perioperative glucose; fructosamine may add information when HbA1c is unreliable.
- Malnutrition / hypoalbuminaemia: Serum albumin less than 3.5 g/dL is the classic marker of malnutrition and independently predicts infection and complications. Screen and correct nutrition; malnutrition can coexist with obesity.
Risk Stratification & Pathway
Optimization sits within a structured elective pathway:
- Screen at listing: history and examination for comorbidities, plus targeted investigations (glycaemic markers, albumin/nutrition screen, full blood count for anaemia, and Staph screening per local protocol).
- Stratify risk: combine comorbidity burden with the modifiable-factor profile to estimate complication and PJI risk; validated risk calculators can support shared decision-making.
- Optimise: set targets and refer/coordinate (primary care, endocrinology, dietetics, anaemia/iron service, smoking cessation, pain service) and defer elective surgery until improved where the risk-benefit balance favours waiting.
- Consent: document the individualised risk and the optimization undertaken.
The single most important principle is that this is elective surgery: time is on your side. A short delay to correct anaemia, improve glycaemic control, achieve smoking cessation, decolonise Staph carriage and address nutrition can meaningfully reduce the risk of a catastrophic complication.
SMOKED INModifiable Risk Factors to Optimise
Hook:A patient who SMOKED IN their risk factors is optimised by reversing each one.
Evidence Base
From Clearance to Optimization (7 Risk Factors)
- Narrative review reframing preoperative care as optimization of modifiable risk factors rather than a binary 'clearance'
- Focuses on seven modifiable factors: obesity, malnutrition, hypoalbuminaemia, diabetes, anaemia, smoking, and opioid use
- Each factor is independently associated with worse outcomes after total joint arthroplasty
- Develops recommendations for optimising each before elective surgery
Viva Scenarios
Practise clinical reasoning and management decisions out loud
“A 64-year-old with a BMI of 41, type 2 diabetes (HbA1c 9.2%), and a 20-pack-year smoking history is referred for a total knee replacement. How do you proceed?”
Guidelines, Registries & Global Practice
Global Consensus Direction
Internationally, preoperative care for arthroplasty has shifted from anaesthetic "clearance" toward structured optimization of modifiable risk factors, reflected in society guidance and enhanced-recovery pathways across North America, the UK/Europe and Australasia. The consistent themes are glycaemic control, nutrition, anaemia management (patient blood management), smoking cessation, weight optimization, and Staph decolonisation, all directed at reducing PJI and complications.
Side-by-Side Synthesis
- Optimization goal
- Improve glycaemic control pre-op
- Why it matters
- Hyperglycaemia raises PJI risk
- Optimization goal
- Correct albumin less than 3.5 g/dL
- Why it matters
- Malnutrition predicts infection/complications
- Optimization goal
- Treat (iron) before surgery
- Why it matters
- Reduces transfusion and complications
- Optimization goal
- Cessation before surgery
- Why it matters
- Fewer wound/infection complications
- Optimization goal
- Screen + decolonise
- Why it matters
- Cheap, high-yield SSI/PJI reduction
- Optimization goal
- Wean pre-op
- Why it matters
- Better pain, function, satisfaction
Practice Variation
Resource-rich systems run dedicated optimization or "joint school" clinics with multidisciplinary input; lower-resource settings achieve much of the benefit with simple, low-cost measures - smoking cessation advice, glycaemic and nutritional screening, treatment of active infection, and Staph decolonisation. The common, universally applicable lever is that arthroplasty is elective: there is time to optimise.
Paradigm
- Optimization, not 'clearance'
- Elective - you can defer to optimise
- Goal: reduce PJI & complications
- Screen → stratify → optimise → consent
Modifiable Factors
- Diabetes / glycaemic control
- Malnutrition (albumin <3.5 g/dL)
- Obesity, anaemia, smoking, opioids
- Staph decolonisation; treat active infection
High-Yield Interventions
- Smoking cessation
- Pre-op anaemia correction (iron)
- Staph nasal/skin decolonisation
- Glycaemic + nutritional optimization