Which of the following is the SINGLE most important modifiable risk factor for periprosthetic joint infection (PJI) after total knee replacement?

• A Age >65 years
• B BMI >40 (morbid obesity) ✓
• C Male sex
• D Preoperative haemoglobin >12 g/dL

Explanation

Morbid obesity (BMI >40) is the single most important modifiable risk factor for periprosthetic joint infection following total knee or hip replacement. The risk increases exponentially with increasing BMI due to: impaired wound healing, reduced tissue perfusion at wound edges, immune dysfunction, increased operative time, and technical difficulties. Most orthopedic guidelines recommend delaying elective arthroplasty until BMI <40 (ideally <35). Other modifiable risk factors include poorly controlled diabetes (HbA1c >7%), malnutrition, active smoking, and poorly controlled rheumatoid arthritis. Age and sex are non-modifiable and carry lower independent risk compared to morbid obesity.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.