Ans. is 'a' i.e., Wrist and hand Ankylosing spondylitis (marie - strumpell disease) Ankylosing spondylitis is a chronic progressive inflammatory disease of the sacroiliac joints and the axial skeleton. Prototype of seronegative (absence of rheumatoid factor) spondyloahropathies. Inflammatory disorder of unknown cause. Usually begins in the second or third decade with a median age of 23, in 5% symptoms begin after 40. Male to female ratio is 2-3 : 1 Strong correlation with HLA-B27 90-95% of cases are positive for HLA - B27. Joints involved in ankylosing spondylitis Primarily affects axial skeleton. The disease usually begins in the sacro-iliac joints and usually extends upwards to involve the lumbar, thoracic, and often cervical spine In the worst cases the hips or shoulders are also affected. o Hip joint is the most commonly affected peripheral joint. o Rarely knee and ankle are also involved. Pathology Enthesitis i.e. inflammation of the inseion points of tendons, ligaments or joint capsule on bone is one of the hallmarks of this entity of disease. Primarily affects axial (spinal) skeleton and sacroiliitis is often the earliest manifestation of A.S.. Involvement of costoveebral joints frequently occur, leading to diminished chest expansion (normal 5 cm) Peripheral joints e.g. shoulders, and hips are also involved in 1/3rd patients. Extraaicular manifestations like acute anterior uveitis (in 5%); rarely aoic valve disease, carditis and pulmonary fibrosis also occur. Pathological changes proceed in three stages? Inflammation with granulation tissue formation and erosion of adjacent bone. Fibrosis of granulation tissue Ossification of the fibrous tissue, leading to ankylosis of the joint. Inflammatory bowel disease (CD, UC) may also be seen. Clinicalfeatures (symptoms) Low back pain of insidious onset Duration usually less than 3 months Significant morning stiffness and improvement with exercise Limited chest expansion Diffuse tenderness over the spine and sacroiliac joints Loss of lumbar lordosis, increased thoracic kyphosis Decreased spinal movements (especially extension) in all directions. Radiological features of an kvlasing spondylitis Radiographic evidence of sacroiliac joint is the most consistent finding in ankylosing spondylitis and is crucial for diagnosis. The findings are :- D Sclerosis of the aiculating surfaces of SI joints Widening of the sacroiliac joint space Bony ankylosis of the sacroiliac joints Calcification of the sacroiliac ligament and sacro-tuberous ligaments Evidence of enthesopathy - calcification at the attachment of the muscles, tendons and ligaments, paicularly around the pelvis and around the heel. X-ray of lumbar spine may show :- Li Squaring of veebrae : The normal anterior concavity of the veebral body is lost because of calcification of the anterior longitudinal ligament. Loss of the lumbar lordosis. Bridging 'osteophytes' (syndesmophytes) Bamboo spine appearance In the early disease process, plain x-rays may be read as normal. More accurate and early diagnosis can be done by using MR1 and/or CT scan. Dynamic MRI with fat saturation, either sho tau inversion recovery (STIR) sequnece or TI weighted images with contrast enhancement is highly sensitive and specific for identifying early intra-aicular inflammation, cailage changes, and underlying bone marrow edema in sacroilitis. Magnetic resonance imaging allows for visualization of acute sacroilitis, spondylitis, and spondylodiscitis, and can also detect acute inflammation of the entheses, bone and synovium. The ability to detect early inflammatiion and acurately visualize cailaginous and enthesal lesions makes magnetic resonance imaging a useful assessment tool in the spondyloahropathies.