Comparison of Periprosthetic Bone Mineral Density between Cruciate-Retaining and Posterior-Stabilised Designs in Cementless Total Knee Arthroplasty

Purpose Cementless total knee arthroplasty (TKA) avoids cement-related complications and has demonstrated favourable implant survival rates. However, postoperative periprosthetic bone resorption may increase the risk of implant migration. In this study, we aimed to compare periprosthetic bone mineral density (BMD) changes between cruciate-retaining (CR) and posterior-stabilised (PS) cementless TKA. Methods We retrospectively analysed 62 knees that underwent cementless TKA between June 2017 and December 2023. Preoperative and postoperative range of motion (ROM) and the 2011 Knee Society Score (KSS) were assessed. Periprosthetic BMD around the tibial component was assessed by measuring the intensity of radiographic images in five predefined regions of interest (ROIs) using ImageJ immediately after surgery, and at 6 and 12 months postoperatively. Results Of the 62 knees, 32 received the CR design and 30 received the PS design. Postoperatively, both groups demonstrated significant improvements in ROM and 2011 KSS (p < 0.001 for both). There were no significant differences in postoperative clinical outcomes between the groups. At 12 months, the PS group had significantly lower relative brightness values in all ROIs than the CR group (p < 0.05). Multiple regression analysis revealed that only implant design influenced periprosthetic BMD loss across all ROIs. Conclusion Compared with CR cementless TKA, PS cementless TKA was associated with greater periprosthetic BMD loss. Careful implant selection and long-term monitoring are necessary to ensure implant stability and evaluate clinical outcomes.