Adolescent patellar instability can occasionally present with significant osteochondral injury, as highlighted by a case involving a large osteochondral fracture and loose body within the knee joint. Such injuries may occur following traumatic patellar dislocation, where shear forces can damage articular cartilage and underlying bone. Prompt recognition through imaging is essential, as displaced osteochondral fragments may contribute to persistent pain, mechanical symptoms, and long-term joint degeneration if left untreated. Management often involves surgical intervention to remove or fix the loose fragment and address underlying patellar instability to reduce the risk of recurrence. This case underscores the importance of early diagnosis and appropriate treatment to preserve joint integrity and optimize functional recovery in adolescent patients.