Medial coronoid disease is commonly diagnosed in young large-breed dogs. The pathophysiology of this important orthopedic problem is not well-defined. As such, a variety of treatment options, including both surgical and conservative approaches, have been proposed. This prospective observational case series documented consistent short- and long-term outcomes for 15 dogs (23 elbows) treated arthroscopically for medial coronoid disease. Outcome measures included radiographic, CT, arthroscopic, force plate, and orthopedic examination observations. Dogs with radioulnar incongruency (RUI) and/or severe cartilage erosion preoperatively exhibited a greater degree of lameness. Postoperative improvement was greater in these dogs, as measured by gait analysis. Clinical assessment of long-term performance ≥2 years after surgery based on muscle mass and gait analysis did improve despite increased osteoarthritis score.