Bone Microstructure And Cement-bone Interfacial Biomechanics Of Osteoarthritis And Rheumatoid Arthritis

Objective Bone cement joint prosthetic aseptic loosening always occurs in the bone cement-bone interface, while the mechanical strength of the interface mainly depends on the microstructure and adhesive strength. In this article we discussed the bone microstructure and the cement-bone interfacial biomechanics of osteoarthritis(OA) and rheumatoid arthritis(RA).Methods 30 cases of trabecular bone specimens of tibial plateaus were taken from OA or RA patients who receiving total knee arthroplasty(TKA). First,20 cases of bone specimens were selected randomly from each group. Using micro-computed tomography(Micro-CT) to measure the microstructural parameters of the bone specimens. Then made the bone specimens into cement-bone models, which were tested by INSTRON strength tester. Analysed the data of bone microstructure and interfacial shear stress, as well as their association. Second, made the rest of specimens into cement-bone models, and tested them by Bose analyzer under a sinusoidal loading between 30 N and 100 N at 3 Hz till failure or 10 thousand cycles. Then compared the shear fatigue strength of these two kinds of disease.Results ①Taking medial tibial plateaus as the reference, bone volume fraction (BV/TV)、trabecular thickness (Tb.Th)、trabecular number (Tb.N) were higher in OA than in RA patients, while bone surface/bone volume (BS/BV)、trabecular spacing (Tb.Sp)、structure model index (SMI)、degree of anisotropy (DA) are lower in OA patients. Taking lateral tibial plateaus as the reference, Tb.Th、Tb.N were greater in OA than in RA cases, while BS/BV、Tb.Sp and DA were lower in OA patients. For OA cases, medial tibial plateaus compared with lateral tibial plateaus, BV/TV、Tb.Th、 Tb.N were higher in medial tibial plateaus,while BS/BV、Tb.Sp、SMI were lower in medial tibial plateaus. For RA cases,BV/TV and Tb.Th of trabecular were less in medial tibial plateaus than in lateral tibial plateaus.②BV/TV(r=-0.313)、 Tb.Th(r=-0.340)、trabecular spacing (Tb.Sp) (r=0.345) of OA correlated with shear strength. The cement-bone interfacial strength of medial tibial plateaus[(87.45±52.50)N] was lower than lateral tibial plateaus[(177.25±71.11)N] of OA. BV/TV (r=0.343)、Tb.N(r=0.391) of RA correlated with shear strength. The cement-bone interfacial shear strength of lateral tibial plateaus[(62.23±46.22)N] was lower than medial tibial plateaus[(79.20±56.37N)] of RA. What’s more, the interfacial shear strength of OA[(132.35±76.64)N] was higher than RA[(71.05±51.55)N].③ Compared with medial tibial plateaus of OA, the cement-bone interface of lateral tibial plateaus can bear longer loading cycles, but opposite outcoming in RA. The shear fatigue strength of cement-bone interface in OA is higher than in RA.Conclusion The microstructure of tibial plateaus between OA and RA are different, which lead to the distinction of bio mechanical strength of cement-bone interface. And it has a certain guiding role in analyzing the biomechanics after TKA.