Effects of different dietary saturated fatty acids consumption on cartilage health: Evidence from preclinical rat models

Purpose: Osteoporosis (OP) can result in decreased bone mineral density, deterioration of bone quality and microarchitectural fracture of the subchondral bone. OP may increase the severity of cartilage damage in osteoarthritis (OA) knee, and the increases in cartilage damage correlate with bone loss and microarchitectural changes. These findings suggest an intimate relationship between OP and OA. Recent studies showed that extracorporeal shockwave therapy (ESWT) is chondroprotective in the initiation of knee OA and the regression of established OA of the knee in rats. However, no study reported an effective method in the prevention or reduction of osteoporotic osteoarthritis of the knee. The aim of the study was to investigate the effectiveness of ESWT in osteoporotic osteoarthritis of rat knee. We hypothesized that ESWT may be effective in the amelioration of osteoporotic osteoarthritis of the knee in rats.

Methods: Fifty-six female Sprague-Dawley (SD) rats were used in this experiment. The rats were divided into seven groups including sham, OA, OP, OA + OP, OA + ESWT, OP + ESWT, and OA + OP + ESWT groups. Group I was the sham group and received sham laparatomy without ovariectomy, and sham arthrotomy without anterior cruciate ligament transection (ACLT) and medial meniscectomy (MM). Group II was the OA group and received ACLT and MM and bilateral ovariectomies. Group III was the OP group and received bilateral ovariectomies. Group IV was OA+OP and received ACLT+MM and bilateral ovariectomies. Group V was OA+ESWT. Group VI was OP+ESWT and bilateral ovariectomes. Group VII was OA+OP+ESWT and received ACLT+MM, bilateral ovariectomies and ESWT. The evaluations included gross pathology, bone mineral density (BMD), micro-computed tomography (micro-CT) scan, bone-strength test, histopathological examination, and immunohistochemical analysis.

Results: On gross pathology, group OA + OP showed significantly larger areas of osteoarthritic changes than group OA and group OP, as compared with the sham group. BMD and bone strength significantly decreased in group OA, group OP, and group OA + OP relative to the sham group. ESWT significantly improved BMD and bone-strength changes. On micro-CT scan, the subchondral plate thickness was significantly decreased, and the bone porosity increased in group OA, group OP, and group OA + OP, and ESWT significantly improved the changes in subchondral-plate thickness and bone porosity. In histopathological examination, Mankin score and Safranin O score significantly increased in group OA and group OA + OP, but not in group OP relative to the sham group, and ESWT significantly improved the changes. In immunohistochemical analysis, Dickkopf-1 (DKK-1) significantly increased, but vessel endothelial growth factor (VEGF), proliferating cell nuclear antigen (PCNA), and bone morphogenetic protein 2 (BMP-2) decreased in group OA, group OP, and group OA + OP relative to the sham group, and ESWT significantly reversed these changes.

Conclusions: Osteoporosis increased the severity of cartilage damage in osteoarthritis of the knee. ESWT showed effectiveness in the amelioration of osteoporotic osteoarthritis of the knee in rats.