Bone Abstracts

Objective: To determine differences between osteoarthritic (OA) knees with normal knees for subchondral trabecular bone structure according to depth and location in the tibial plateau.

Methods: In a population of 30 cadaveric left knees (18 women and 12 men, mean age: 79.1 years±8.2, range: 63–90) the Kellgren-Lawrence (KL) score was determined from post mortem radiographs: OA=KL≧2 (n=6 women, n=5 men) and controls=KL ≤1.

After dissection, two vertical cores (7 mm in diameter) were extracted in the central region of the medial tibial plateau (S1) not covered by meniscus and peripheral (S2) fully covered by the meniscus. Each core was imaged with micro-CT (SkyScan 1172®) pixel size 10.23 μm. In the first 1–5 mm and the 6–10 mm beneath the subchondral bone plate: Bone Volume/Total Volume (BV/TV,%), Trabecular Number (Tb.N,1/mm), Trabecular Thickness (Tb.Th,mm), Trabecular Separation (Tb.Sp,mm), Degree of Anisotropy (DA), Structure Model Index (SMI) and Trabecular Bone Factor (Tb.Pf) were measured.

To investigate differences in trabecular bone structure between OA and controls, a separate analysis of covariance with age as covariate was performed for men and women separately.

Results: At 1-5mm, in G1 location for both men and women, Tb.N, Tb.Sp, Tb.Pf and SMI were significantly different (0.04<P< 0.001), for men BV/TV was also different (P=0.006) and for women DA (P=0.01). In G2 location for both men and women, BV/TV and Tb.N were significantly different (0.04<P<0.02). Tb.Sp and DA were also significantly different in women P=0.01 and P=0.03, respectively. At 6–10 mm, there was no difference of any parameters between OA and controls in both men and women.

Conclusions: We conclude that the impact of OA in subchondral bone was only present in the first 5mm beneath the subchondral plate with constantly found an increase of Tb.N, and in a lesser extend a greater connectivity, a more plate like structure and a decrease of anisotropy.