Assessment of bone mineral density at the bone-implant interface and joint temperature in patients undergoing total knee arthroplasty

The field of knee prosthetic surgery has undergone significant advancements to enhance patient outcomes and implant longevity. While innovations in design, alignment, soft tissue balancing, and fixation techniques have progressed, material-related challenges remain crucial. Traditional cobalt-chrome (CoCr) prostheses exhibit distinct disparities compared to human bone in stiffness and thermal conductivity. Excessive stiffness leads to “stress shielding,” contributing to periprosthetic bone resorption, implant loosening, and fractures. High thermal conductivity, in contrast, often causes patient discomfort, such as altered heat sensitivity in the operated knee. These challenges underscore the need for novel materials, particularly as osteoarthritis arises earlier and joint replacement increasingly targets younger, active patients. This PhD thesis investigates the influence of joint prostheses on periprosthetic bone remodeling and joint temperature trends, with a focus on Total Knee Arthroplasty (TKA). The research objectives included: (I) a literature review on femoral component migration and clinical outcomes; (II) a systematic review on periprosthetic Bone Mineral Density (BMD) variations, influenced by fixation techniques and implant design; (III) a clinical study utilizing Dual X-ray Absorptiometry (DXA) to assess BMD changes post-TKA; and (IV) an evaluation of postoperative knee surface temperature. The findings demonstrated that femoral component migration exceeding 0.10 mm annually correlates with implant failure, often linked to poor primary fixation and low BMD. Systematic analysis revealed progressive BMD reduction post-TKA, influenced by fixation and implant design. Clinical DXA evaluations, a first at Rizzoli Orthopedic Institute, showed promising preliminary results regarding CoCr prostheses’ impact on BMD. Finally, increased postoperative knee temperatures aligned with patients' subjective discomfort and correlated with clinical outcomes. This thesis provides a foundation for developing biocompatible materials to enhance prosthetic durability, reduce bone resorption, and improve patient satisfaction.