A new approach to quantify trabecular resorption adjacent to cemented knee arthroplasty

Area of Science:

• Biomedical Engineering
• Orthopedic Surgery
• Materials Science

Background:

• Total knee arthroplasty (TKA) relies on cement-bone interlock for fixation.
• Loss of this interlock due to bone resorption can lead to implant loosening.
• Quantifying cement-bone interlock degradation in vivo is challenging.

Purpose of the Study:

• To develop and validate a novel micro-computed tomography (microCT) image processing approach.
• To estimate the loss of cement-bone interlock and quantify trabecular bone resorption.
• To analyze changes in cement-bone fixation following in vivo service.

Main Methods:

• Developed a microCT image processing technique using cement mold shape and Boolean operations.
• Utilized laboratory specimens as controls to validate the method and estimate errors.
• Applied the technique to en bloc human postmortem retrievals from TKA patients.

Main Results:

• Laboratory specimens showed minimal errors in estimating resorbed bone volume fraction (reBVfr=0.11 ± 0.09) and contact area fraction loss (CAfr=0.06 ± 0.15).
• Postmortem retrievals demonstrated substantial bone loss, with reBVfr of 0.85 ± 0.16 and CAfr of 0.84 ± 0.17.
• The study visualized and quantified significant degradation of cement-bone interlock after in vivo service.

Conclusions:

• The developed microCT approach accurately quantifies cement-bone interlock loss and trabecular bone resorption.
• Significant bone loss occurs around PMMA cement following in vivo TKA service.
• This method provides a valuable tool for analyzing implant fixation degradation in postmortem retrievals.