Osteochondral allograft (OCA) transplantation can functionally restore large articular defects in the knee. Bipolar OCA transplantations for partial and whole joint resurfacing often have less favorable results than single-surface transplants. This study was designed to use a large animal model to test the hypothesis that unicompartmental bipolar osteochondral and meniscal allograft transplantation (BioJoint) would be as or more effective for treatment of medial compartment osteoarthritis (OA) compared to standard-of-care non-operative treatment. OA was induced in one knee of each research hound (n=8) using a meniscal release model and pre-treatment assessments were performed. After 3 months, dogs were randomly assigned to either the Control group (n=4, no surgical intervention, daily non-steroidal anti-inflammatory drugs (NSAIDs) or the BioJoint group (n=4). Clinical, radiographic, and arthroscopic assessments were performed longitudinally and histopathology was evaluated at the 6-month endpoint. At study endpoint, functional, pain and total pressure index measures, as well as radiographic and arthroscopic grading of graft appearance and joint health, demonstrated superior outcomes for BioJoints compared to NSAID Controls. Furthermore, histologic assessments showed that osteochondral and meniscal transplants maintain integrity and integrated into host tissues. Clinical significance: The results support the safety and efficacy of unicompartmental bipolar osteochondral and meniscal allograft transplantation in a preclinical model with highly functional outcomes without early OA progression. This article is protected by copyright. All rights reserved.