Osteochondritis Dissecans

Case presentation
A 56 year old woman presents with 3 day history of gradually worsening pain and swelling in her left knee.Denies any injury,temperature or other complaints.Never experienced this type of pain before and states that she is fairly active and fit.Vital signs normal.On examination of the knee,noted slight effusion and slightly limited range of motion.
Differential diagnosis,torn meniscus,osteoarthritis and infection.
Referred for knee x-ray.Noted on results a small bony object maybe a “joint mouse” resulting from osteochondritis dissecans.