The dimensional accuracy for preparation of the femoral cavity in HIP arthroplasty

Abstract

The aim of the study was to determine the precision of the preparation of the femoral cavity in cementless hip arthroplasty. We compared the bone-prosthesis interface after manual- and robot-assisted implantation of the stems. After plastination the specimens were cut to slices of 2.5 mm and documented by microradiography. The interface between prosthesis and bone was measured digitally with a specially designed software. The manually implanted prostheses showed an average full-contact area of 60% and an average area of gaps of 40% with an average height of 0.8 mm. The robot-assisted implanted stems had a significantly higher bone-prosthesis interface area of 93% and gap areas of less than 0.2 mm depth. Destructions of the spongeous bone were seen with the manually implanted stems but not after robot-assisted implantations. There was one stem fracture during the manual preparation of a stem. Microradiographic examination showed microfractures in the region of the lesser trochanter in two femora after robot-assisted implantation The robot-assisted technique highly increased the fitting area at the bone-prosthesis interface. The main reason for the fractures might be the absence of a robot done marker for the ideal implantation height with the applied type of prosthesis.