Dr. Leonard T Onsen, MD

Dr. Leonard “Tiger” Onsen, MD is a dedicated orthopedic surgeon at OrthoIllinois, providing comprehensive care to patients through OSF HealthCare. His journey into orthopedic medicine was inspired by personal experiences with sports-related injuries during his high school years. These encounters with lengthy treatments and surgical recovery gave him firsthand appreciation for the profound impact physicians can have on restoring a patient’s quality of life and enabling them to return to the activities they love.

Dr. Onsen graduated Cum Laude from Illinois Wesleyan University in Bloomington. He earned his medical degree from The University of Illinois College of Medicine at Chicago, where he also completed his residency training in orthopedic surgery. During his residency, Dr. Onsen developed a passion for sports medicine—a specialty that not only allowed him to address a wide range of musculoskeletal conditions but also resonated with his lifelong love of sports and his desire to work …with athletes. To further his expertise, he pursued advanced fellowship training in Sports Medicine at Cedars Sinai Kerlan Jose Institute.

In his OrthoIllinois practice through OSF Medical Group, Dr. Onsen specializes in surgery of the knee, shoulder, and elbow. His clinical focus includes ligament reconstructions, tendon repairs, and cartilage procedures. He is committed to helping athletes return to their sport and all patients regain functional and active lifestyles.

Dr. Onsen believes in fostering a comfortable and collaborative environment where patients can make informed decisions about their care. He emphasizes education, advocacy, and mutual respect, ensuring that each patient leaves his office with a clear understanding of their condition, available treatment options, and a strong sense of partnership in their treatment and recovery journey.

Outside of his medical practice, Dr. Onsen enjoys spending time with his wife and young son, exploring new restaurants, and attending movies. He is an enthusiastic supporter of the Chicago Bears, Cubs, Bulls, and Blackhawks, and makes it a point to follow their games and highlights whenever possible.