This multicenter retrospective study asks: what HbA1c level actually predicts periprosthetic joint infection after total joint arthroplasty? Using ROC analysis in 1,645 diabetic patients, it derives a data-driven threshold specific to the TJA population. The answer challenges the widely used 7% cutoff borrowed from general diabetes management guidelines.
Orthopedic surgeons have long used HbA1c <7% as the preoperative glycemic target before TJA, borrowed directly from American Diabetes Association guidelines for general diabetes management. The problem: no data validated that cutoff specifically for TJA patients, and multiple studies using the 7% threshold failed to show any association with PJI.
This paper resets that threshold. When a diabetic patient presents for TJA optimization, the target should be HbA1c <7.7%, not <7%. Patients with HbA1c between 7% and 7.7% do not appear to carry elevated PJI risk and should not have surgery delayed.
Above 7.7%, PJI risk rises nearly sevenfold (0.8% to 5.4%), and HbA1c becomes the only independent predictor of infection in multivariate analysis. This is the decision rule: optimize to below 7.7% before elective TJA, and do not reflexively hold patients at the lower 7% bar.
One nuance worth knowing: high HbA1c predicts PJI specifically — it does not predict wound complications, DVT, cardiovascular events, or readmission. The glycemic-infection link appears to be the dominant risk, not a broad complication signal.
This multicenter retrospective study asks: what HbA1c level actually predicts periprosthetic joint infection after total joint arthroplasty? Using ROC analysis in 1,645 diabetic patients, it derives a data-driven threshold specific to the TJA population. The answer challenges the widely used 7% cutoff borrowed from general diabetes management guidelines.
Orthopedic surgeons have long used HbA1c <7% as the preoperative glycemic target before TJA, borrowed directly from American Diabetes Association guidelines for general diabetes management. The problem: no data validated that cutoff specifically for TJA patients, and multiple studies using the 7% threshold failed to show any association with PJI.
This paper resets that threshold. When a diabetic patient presents for TJA optimization, the target should be HbA1c <7.7%, not <7%. Patients with HbA1c between 7% and 7.7% do not appear to carry elevated PJI risk and should not have surgery delayed.
Above 7.7%, PJI risk rises nearly sevenfold (0.8% to 5.4%), and HbA1c becomes the only independent predictor of infection in multivariate analysis. This is the decision rule: optimize to below 7.7% before elective TJA, and do not reflexively hold patients at the lower 7% bar.
One nuance worth knowing: high HbA1c predicts PJI specifically — it does not predict wound complications, DVT, cardiovascular events, or readmission. The glycemic-infection link appears to be the dominant risk, not a broad complication signal.