Related Experiment Video
Updated: Nov 9, 2025
Individualized Stem-positioning in Calcar-guided Short-stem Total Hip Arthroplasty
Published on: February 27, 2018
Using a ring to locate femoral head centre in total hip arthroplasty
Owen J Diamond1, Janet C Hill1, Aaron J McCann2
1Primary Joint Unit, Musgrave Park Hospital, Belfast Health and Social Care Trust, Belfast, UK.
Aims:
Traditional methods of determining femoral head centre (FHC) during total hip arthroplasty (THA) rely on measuring the distance from a fixed point on the femur or using a calliper. The aim of this experiment was to investigate how accurately a simple circular ring could locate FHC.
Methods:
144 consecutively available femoral heads (FHs) were collected from patients undergoing THA. Each FH was orientated and mounted on a Sawbone, to create a model of its position on a proximal femur. The ring was applied to the posterior aspect of the FH and a head-centre pin (HCP) was then drilled into the FH and the ring removed, leaving the HCP in place.Each FH was then photographed normal to the axis of the HCP. A MATLAB analysis program then assessed the accuracy of the ring in locating FHC.
Results:
Mean location accuracy for FHC was 1.77 (range 0.07-5.83) mm with 97.2% within 4 mm and all but 1 within 5 mm.
Conclusions:
This ring device located FHC to within 4 mm in 97% of a series of osteoarthritic FHs. This indicates that the posterior aspect of the FH maintains its sphericity late into the osteoarthritic process. Having a simple FHC location device during THA would be of value to control leg length and offset when using the posterior approach.
