What pre‑operative assessments and optimizations are needed to obtain surgical clearance for a knee replacement?

Preoperative Assessment and Optimization for Knee Replacement

Obtain surgical clearance through a focused cardiovascular risk assessment, optimization of modifiable medical conditions, and prehabilitation—deferring surgery when high-risk factors remain unaddressed.

Cardiovascular Risk Assessment

The preoperative evaluation begins with a focused history and physical examination specifically assessing cardiovascular risk factors, functional status, and the presence of active cardiac conditions 1.

• For knee replacement (intermediate-risk surgery), extensive preoperative cardiac testing is not routinely indicated in asymptomatic patients with good functional capacity 1.
• Reserve cardiac stress testing or advanced imaging for patients with poor or unknown functional capacity who have multiple cardiovascular risk factors or active cardiac symptoms 1.
• The 2024 AHA/ACC guideline emphasizes that little evidence supports extensive preoperative testing for procedures like knee replacement, and care is rarely improved by additional cardiovascular testing in low-to-intermediate risk surgeries 1.

Modifiable Risk Factor Optimization

Screen all knee replacement candidates for the following modifiable risk factors and optimize before proceeding with surgery 2, 3:

Metabolic and Nutritional Factors

• Diabetes mellitus: Achieve HbA1c < 8% (ideally < 7%) before surgery 3.
• Obesity: Target BMI < 40 kg/m² (or < 35 kg/m² with comorbidities); consider delaying surgery for BMI > 40 kg/m² until weight reduction achieved 2, 3.
• Anemia: Correct preoperative anemia (hemoglobin < 13 g/dL in men, < 12 g/dL in women) to reduce transfusion risk 3, 4.
• Malnutrition and vitamin D deficiency: Screen and correct nutritional deficiencies, particularly vitamin D levels 3.

Behavioral and Medication Factors

• Tobacco use: Mandate smoking cessation at least 4–6 weeks before surgery 3.
• Opioid use: Wean or minimize chronic opioid therapy preoperatively, as it increases postoperative complications 3.
• Poor dentition: Complete necessary dental work before surgery to reduce infection risk 3.

Sleep and Psychiatric Conditions

• Obstructive sleep apnea: Screen using validated tools; optimize CPAP therapy if diagnosed (present in 52% of screened patients in one protocol) 2.
• Depression: Identify and treat depression, which affects 22% of arthroplasty candidates 2.

Infection Prevention

Complete a comprehensive infection risk assessment 4:

• Screen for active infections (urinary tract, skin, dental, respiratory) and treat before surgery 4.
• Optimize glycemic control as noted above, since hyperglycemia increases surgical site infection risk 4.
• Ensure appropriate preoperative antibiotic prophylaxis is planned according to institutional protocols 4.

Prehabilitation and Functional Optimization

Enroll patients in a structured preoperative exercise program (prehabilitation) that strengthens quadriceps and improves functional capacity 3, 5:

• Moderate-quality evidence demonstrates that preoperative exercise reduces pain before knee replacement (SMD 0.43) 5.
• Combine exercise with patient education programs to improve postoperative functional milestones and reduce hospital length of stay 5.
• Prehabilitation is particularly important for patients with poor baseline functional status 3.

Blood Management Strategy

Implement a preoperative blood management protocol 4:

• Screen hemoglobin levels 2–4 weeks before surgery 4.
• Administer iron supplementation (oral or IV) or erythropoietin for anemic patients 4.
• Plan tranexamic acid administration perioperatively to reduce blood loss 4.

Pain Management Planning

Develop a multimodal pain management strategy preoperatively 4:

• Educate patients about realistic pain expectations and the multimodal approach 4.
• Plan for regional anesthesia techniques (adductor canal blocks, periarticular injections) in addition to systemic analgesia 4.
• Minimize or eliminate preoperative opioid use as noted above 3.

Imaging Assessment

Obtain bilateral knee radiographs (AP, lateral, tunnel/Rosenberg, and patellar tangential views) even for unilateral symptoms, as contralateral pathology may be biomechanically significant 6.

• If knee radiographs are unremarkable but pain persists, obtain hip radiographs to exclude referred hip pathology 6.

Common Pitfalls

Do not proceed with surgery when high-risk modifiable factors remain unaddressed—implementation of optimization protocols has demonstrated reduced length of stay (1.9 vs 2.2 days) and lower costs ($5409 vs $5852) without increasing readmissions 2. However, one study found that 20% of patients did not follow through with recommended optimization, highlighting the need for clear communication about surgical postponement when optimization is incomplete 2.

Avoid the assumption that optimization checklists alone are sufficient—one study showed that checklists without detailed optimization protocols failed to reduce 90-day emergency department visits or readmissions 7. The key is implementing specific interventions for each identified risk factor, not merely documenting their presence 7.