Which risk factor had the highest odds ratio for SSI after knee arthroplasty?

• A. Pre-operative hair removal
• B. Inadequate preparation
• C. Inadequate glucose control
• D. Contaminated/dirty surgery

Answer: (D)

Contamination level in the surgical wound drives infection risk the most. When a knee arthroplasty involves a contaminated or dirty wound, there’s a substantial microbial burden introduced into the field, and with an implanted prosthesis, bacteria can readily adhere to surfaces and form biofilms that are hard to eradicate. This combination creates the strongest link to a surgical site infection, producing the highest odds ratio among the factors listed.

Other factors can raise SSI risk, but their impact is typically smaller in magnitude. For example, inadequate glucose control can impair immune function and healing, and suboptimal preparation or hair removal practices can contribute to risk, but they don’t carry as much weight as a contaminated or dirty wound in the context of knee replacement with an implanted device.