Which is the least affected joint in Ankylosing spondylitis

In patients eventually diagnosed with AS, symptoms are usually first noticed in late adolescence or early adulthood, at a median age in the mid-twenties. In 5% of patients, symptoms begin after age 40. The initial symptom is usually dull pain, insidious in onset, felt deep in the lower lumbar or gluteal region, accompanied by low-back morning stiffness of up to a few hours' duration that improves with activity and returns following inactivity. Within a few months, the pain has usually become persistent and bilateral. Nocturnal exacerbation of pain often forces the patient to rise and move around. In some patients, bony tenderness (presumably reflecting enthesitis or osteitis) may accompany back pain or stiffness, whereas in others it may be the predominant complaint. Common sites include the costosternal junctions, spinous processes, iliac crests, greater trochanters, ischial tuberosities, tibial tubercles, and heels. Hip and shoulder ("root" joint) ahritis is considered pa of axial disease. Hip ahritis occurs in 25-35% of patients. Shoulder involvement may be at least as common, but is usually less symptomatic. Severe isolated hip ahritis or bonychest pain may be the presenting complaint, and symptomatic hipdisease can dominate the clinical picture. Ahritis of peripheral joints other than the hips and shoulders, usually asymmetric, may occur at any point in the disease course. Neck pain and stiffness from involvement of the cervical spine are usually relatively late manifestations, but are occasionally dominant symptoms. Ref Harrisons 20e p2567