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Spine in Ankylosing Spondylitis

- See: Cervical Spine in Ankylosing Spondylitis

- Clinical Findings:
    - loss of lumbar lordosis;
    - back motion is limited;
           - note that ability to lean forward has more to do with hip flexion than lumbar spine flexion;
           - w/ forward flexion there should be a reversal of the normal lumbar lordosis;
    - hip flexion contractures or cervicothoracic kyphosis is common;
           - these conditions require correction;
    - may have fixed cervical, thoracic, or lumbar hyperkyphosis;
    - may cause marked functional limitations, primarily due to inability of affected patients to face forward;
    - pts may have diminished chest expansion;

- Spine Frx in AS:
      - progressive neural deterioration;
      - loss of reduction
      - epidural hematoma;
            - neurologic deficit occuring at higher level than at frx site may indicate expanding hematoma which is more common in AS;
      - non union;
      - occult frx;
      - progressive kyphosis;
      - death in > 50% of cases;

- Radiographic Changes:


    - symmetric, bilateral subchondral erosions of the sacroiliac joints;
          - subchondral sclerosis then follows, first on the iliac side and then on both sides of the joints.
    - disease first affects lumbar spine and then ascends to thoracic spine;
    - vertebrae appear squared off on the lateral radiographs.
    - longitudinal ligaments & annulus ossify, creating marginal syndesmophytes;
          - spine takes on bamboo appearance from the sacrum to the occiput;
          - SI joint obliteration & marginal syndesmophytes allow radiographic differentiation from DHIS;
          - in Reiter's syndrome and Psoriatic Arthritis, beaklike nonmarginal syndesmophytes may be seen;
    - fascet joint are simultaneously obliterated;

- Treatment:
    - C-spine may be corrected by C7-T1 osteotomy & fusion w/ local anesth;
    - complications of osteotomies include nonunion, loss of correction, & neurologic and aortic injury;
    - extension osteotomy and fusion of the lumbar spine with compression instrumentation can successfully balance the head over the sacrum

Thoracolumbar fractures in ankylosing spondylitis. High-risk injuries.

The pathogenesis of extensive discovertebral destruction in ankylosing spondylitis.

Secure fixation of lumbar osteotomy. Surgical experience with 50 patients.