Anterior femoral notching in total knee arthroplasty assisted with 3D printed patient-specific instrumentation: a cause analysis

Abstract

Objective To find out the causes of anterior femoral notching in 3D printed patient-specific patient-specific instrumentation (PSI) assisted total knee arthroplasty (TKA). Methods A retrospective analysis was carried out on the consecutive cases undergoing PSI assisted TKA in the Peking University International Hospital from January 2019 to September 2021. The clinical data of those having anterior femoral notching were collected. 3D CT scanning was performed on the knee joint after intraoperative osteotomy and the intraoperative bone fragments. Rapidform software (Version 2006) was used to reconstruct 3D images and to perform image registration and comparison analysis with the preoperatively planned 3D models. The anterior femoral notching depth was measured, and the differences in the thickness of bone fragments between preoperatively planned and intraoperative bone cutting in order to analyze the causes of the anterior femoral notching. Results A total of 86 consecutive cases (94 knees) were included and 17 cases (18/94, 19.1%) of them had anterior femoral notching. The causes of anterior femoral notching were summarized into 3 categories: abnormal position of the PSI (10 cases, 83.3%), intraoperative reduction of the femoral prosthesis size (2 cases, 16.7%), and overextension of the femoral prosthesis (1 case, 8.3%). Conclusion Abnormal femoral PSI position, intraoperative reduction of femoral prosthesis size, and preoperative femoral prosthesis overextension design are the main causes of anterior femoral notching after PSI assisted knee arthroplasty.

Keywords

• 3d printing technology
• patient-specific instrumentation knee replacement
• anterior femoral notching
• imaging
• three-dimension