Chronological Changes in Sagittal Femoral Bowing after Primary Cementless Total Hip Arthroplasty: A Comparative 3D CT
Francesco Pardo1, Antonino Amedeo La Mattina2,3, Emanuele Diquattro1
1Orthopedics-Traumatology and Prosthetic Surgery and Hip and Knee Revision, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy.
Insights
Cementless total hip arthroplasty (THA) alters sagittal femoral bowing (SFB) in the proximal femur. This study found significant chronological changes in SFB after at least three years post-surgery.
Area of Science:
- Orthopedic Surgery
- Biomedical Engineering
- Radiology
Background:
- Dynamic changes in femoral anatomy after total hip arthroplasty (THA) are not well understood.
- Sagittal femoral bowing (SFB) is a key anatomical feature potentially affected by THA.
Purpose of the Study:
- To evaluate chronological changes in SFB after cementless femoral stem implantation in primary THA.
- To investigate the long-term effects of cementless stems on femoral morphology.
Main Methods:
- A 3D CT study involving ten patients undergoing unilateral primary THA.
- Two CT scans (pre-operative and at least 3 years post-operative) were used to create 3D femur models.
- SFB was calculated for the proximal and middle thirds of the femur on both operated and contralateral sides.
Main Results:
- No significant inter-observer variability was found in SFB measurements.
- A significant difference in SFB was observed between pre-operative and post-operative states in the proximal femur (p=0.004).
- Chronological changes in SFB were induced by cementless stem use in the proximal femur.
Conclusions:
- Cementless femoral stems in THA lead to chronological alterations in proximal femoral sagittal bowing.
- These changes become apparent after a minimum of three years post-implantation.
Abstract:
Little is known about dynamic changes of femoral anatomy after total hip arthroplasty (THA), in particular about sagittal femoral bowing (SFB). A 3D CT study was designed to evaluate the chronological changes of SFB after cementless femoral stem implantation for primary THA. Ten patients who underwent unilateral primary THA with a cementless femoral stem, with 2 consecutive CT scans (extending from the fourth lumbar vertebra to the tibial plateaus), performed before THA and at least 3 years after THA, were enrolled. The 3D models of femurs were created using image segmentation software. Using the two CT scans, SFB values of the proximal and middle thirds were calculated on the replaced and untreated sides by two different observers. Eight anatomical stems and two conical stems were involved. The post-operative CT was performed at an average follow-up of 6.5 years after THA (range: 3-12.5). The measurements performed by the two observers did not differ in the proximal and middle regions. A significant difference between the pre-operative and post-operative SFB compared to the untreated side was found in the proximal femur segment (p = 0.004). Use of a cementless stem in THA induced chronological changes in SFB of the proximal femur, after a minimum timespan of 3 years.
