Automated detection & classification of knee arthroplasty using deep learning

Paul H. Yi, Jinchi Wei, Tae Kyung Kim, Haris I. Sair, Ferdinand K. Hui, Gregory D. Hager, Jan Fritz, Julius K. Oni

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Background: Preoperative identification of knee arthroplasty is important for planning revision surgery. However, up to 10% of implants are not identified prior to surgery. The purposes of this study were to develop and test the performance of a deep learning system (DLS) for the automated radiographic 1) identification of the presence or absence of a total knee arthroplasty (TKA); 2) classification of TKA vs. unicompartmental knee arthroplasty (UKA); and 3) differentiation between two different primary TKA models. Method: We collected 237 anteroposterior (AP) knee radiographs with equal proportions of native knees, TKA, and UKA and 274 AP knee radiographs with equal proportions of two TKA models. Data augmentation was used to increase the number of images for deep convolutional neural network (DCNN) training. A DLS based on DCNNs was trained on these images. Receiver operating characteristic (ROC) curves with area under the curve (AUC) were generated. Heatmaps were created using class activation mapping (CAM) to identify image features most important for DCNN decision-making. Results: DCNNs trained to detect TKA and distinguish between TKA and UKA both achieved AUC of 1. Heatmaps demonstrated appropriate emphasis of arthroplasty components in decision-making. The DCNN trained to distinguish between the two TKA models achieved AUC of 1. Heatmaps showed emphasis of specific unique features of the TKA model designs, such as the femoral component anterior flange shape. Conclusions: DCNNs can accurately identify presence of TKA and distinguish between specific arthroplasty designs. This proof-of-concept could be applied towards identifying other prosthesis models and prosthesis-related complications.

Original languageEnglish (US)
Pages (from-to)535-542
Number of pages8
Issue number2
StatePublished - Mar 2020


  • Artificial intelligence
  • Deep learning
  • Knee Arthroplasty
  • Knee prosthesis
  • Neural networks

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine


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