27-Week avocado-soybean unsaponifiables treatment in a knee osteoarthritis rabbit model: histomorphometric assessment of potential disease-modifying effects.

Osteoarthritis is a chronic degenerative joint disease that affects cartilage and subchondral bone, and there is growing interest in nutraceuticals such as avocado-soybean unsaponifiables as potential disease-modifying agents and possible alternatives to nonsteroidal anti-inflammatory drugs. This study aimed to evaluate the long-term effects of daily oral avocado-soybean unsaponifiables on cartilage and subchondral bone in a surgically induced knee osteoarthritis rabbit model using quantitative histomorphometric, histological and immunohistochemical analyses. Osteoarthritis was induced by anterior cruciate ligament transection plus partial meniscectomy in one knee of adult New Zealand White rabbits, while contralateral knees served as healthy controls and a sham-operated group controlled for surgical manipulation; animals received placebo or avocado-soybean unsaponifiables for 24 weeks before joints were collected for undecalcified and decalcified histology, histomorphometry and collagen type II and type X immunohistochemistry. Osteoarthritic joints showed increased cartilage thickness and surface fibrillation, with a tendency toward subchondral bone thinning beneath affected regions, confirming successful induction of osteoarthritis, whereas trabecular bone parameters and collagen type II expression did not differ significantly between treatment groups, and collagen type X expression increased in osteoarthritic groups compared with sham-operated joints. Long-term avocado-soybean unsaponifiable treatment did not reduce hypertrophic cartilage response, surface fibrillation, trabecular bone loss or collagen remodeling markers, suggesting limited structural efficacy in this model under the evaluated conditions.