M20-M25: Other joint disorders

M22: Disorders of patella

Disorders of the patella, or kneecap, encompass various conditions that impact the proper functioning of the knee joint. These disorders typically involve issues with the alignment or movement of the patella as it slides over the lower end of the thigh bone, or femur, which can cause discomfort, instability, and decreased mobility. Some of the most common patella disorders include patellar dislocation, patellofemoral pain syndrome, chondromalacia patellae, and patellar tendinitis. The symptoms can range from knee pain and swelling to difficulty walking or a grating feeling when bending the knee. These disorders can be caused by injury, inflammation, wear and tear over time, or anatomical abnormalities. The progression of patellar disorders varies, with certain conditions resulting in degeneration of the knee joint if left untreated.