Utilization of Machine Learning Models to More Accurately Predict Case Duration in Primary Total Joint Arthroplasty.

Introduction: Accurate operative scheduling is essential for the appropriation of operating room (OR) resources. We sought to implement a machine learning (ML) model to predict primary total hip (THA) and total knee arthroplasty (TKA) case time.

Methods: A total of 10,590 THAs and 12,179 TKAs between July 2017 and December 2022 were retrospectively identified. Cases were chronologically divided into training, validation, and test sets. The test set cohort included 1,588 TKAs and 1,204 THAs. There were four machine learning algorithms developed: linear ridge regression (LR), random forest (RF), XGBoost (XGB), and explainable boosting machine (EBM). Each model's case time estimate was compared to the scheduled estimate measured in 15-minute "wait" time blocks ("underbooking") and "excess" time blocks ("overbooking"). Surgical case time was recorded, and SHAP (Shapley Additive exPlanations) values were assigned to patient characteristics, surgical information, and the patient's medical condition to understand feature importance.

Results: The most predictive model input was "median previous 30 procedure case times." The XGBoost model outperformed the other models in predicting both TKA and THA case times. The model reduced TKA 'excess time blocks' by 85 blocks (P < 0.001) and 'wait time blocks' by 96 blocks (P < 0.001). The model did not significantly reduce 'excess time blocks' in THA (P = 0.89) but did significantly reduce 'wait time blocks' by 134 blocks (P < 0.001). In total, the model improved TKA operative booking by 181 blocks (2,715 minutes) and THA operative booking by 138 blocks (2,070 minutes).

Conclusions: Machine learning outperformed a traditional method of scheduling total joint arthroplasty (TJA) cases. The median time of the prior 30 surgical cases was the most influential on scheduling case time accuracy. As ML models improve, surgeons should consider machine learning utilization in case scheduling; however, prior 30 surgical cases may serve as an adequate alternative.