UC San Diego

Osteochondral cores (OC) consist of articular cartilage, trabecular bone, and the subchondral plate (ScP). Subcomponents change during maturation and degeneration with osteoarthritis. The goal of this thesis was to determine if OC electrical impedance and resistivity differ with tissue maturation or degeneration and if these differences are primarily due to the ScP.(1) By performing impedance measurements across tubes of varying lengths, resistivity of PBS (1x, 1/10x) was established. (2) The impedance (Z) of immature bovine OC was reduced by 30% after marrow removal via centrifugation. (3) Bovine ScP maturation affected ZOC. In 1x PBS, bCalf-ZOC was 8% of bAdult. ScP+TB accounted for 51% of the summed subcomponent impedances in bCalf and 76% in bAdult. ZScP+TB-bCalf was 5% of bAdult. After partial and complete equilibration in 1/10x PBS, ZScP+TB was 30%, 113% (partial) and 54%, 98% (complete) of the subcomponent total, for bCalf and bAdult respectively. (4) Osteoarthritic degeneration did not markedly affect ZOC in adult human remnant tissue from surgeries. In 1xPBS, ZOC was indistinguishable between osteoarthritic total knee replacement tissue (OA- hAdult, 92 ± 37 %) and normal allograft tissue (NL-hAdult), with ScP accounting for 100% OA-hAdult and 99% of NL-hAdult. ZScP+TB in OA-hAdult was 106 ± 58% of NL-hAdult. Similar trends were evident after soak in 1/10x PBS. These studies established the increasing contribution of ScP to ZOC with maturation. ZOC is a biophysical property that may have novel applications to biomimetic OC tissue engineering.