Low Preoperative Platelet Count Is Associated With Deep Surgical Site Infection in Knee Arthroplasty

Knee arthroplasty (KA) significantly improves pain and function in gonarthrosis. Despite its success, major complications like deep surgical site infection (SSI) remain a concern. Infection treatments often require aggressive protocols, including implant exchange and prolonged antimicrobial therapy, emphasizing the need for preoperative patient optimization to mitigate infection risk. Preoperative platelet count has been proposed as a predictive marker for postoperative infection. Beyond their hemostatic role, platelets possess antimicrobial properties and are considered the first line of defense against microbial proliferation within the surgical site. This database review aims to assess the relationship between preoperative platelet count and deep SSI.

The National Surgery Quality Improvement Program was queried for patients who underwent primary total or unicompartmental KA between 2015 and 2022 and developed deep SSI within 30 days. Postoperative outcomes were analyzed with respect to platelet count as a continuous and categorical variable.

Deep SSI was significantly more common in patients with preoperative platelet counts <150,000/μl compared to those with higher counts (0.61% vs 0.30%; P < .001). Regression analysis assessed the independent association of preoperative platelet count with deep SSI. The odds ratio for deep SSI with platelet count <50k/μl was 2.47 (1.42-4.28; P = .001), 1.87 (1.08-3.24; P = .026) for platelet count between 50-100k/μl, and 1.62 (1.32-2.00; P < .001) for platelet count between 100-150k/μl, all in reference to patients with platelet counts >150k/μl.

Thrombocytopenia (<150,000 platelets/μl) is significantly associated with a higher incidence of deep SSI following KA. Preoperative platelet count may serve as a useful marker for infection risk.