This systemic illness of unknown origin involves the spine and larger joints. It predominantly affects men from ages 20 to 40 years and results in pain and stiffness that result from inflammation of the SI, intervertebral, and costovertebral joints in addition to paraspinal calcification with ossification and ankylosis of the spinal joints. IT may cause complete rigidity of the spine and thorax which is usually seen in the SI joints. 

Is usually due to trauma or improper lifting. The soft inner part of the intervertebral disk protrudes through the fibrous outer layer, pressing on the spinal cord or nerves. IT occurs most frequently at the L4 level causing sciatica. Plain radiographs do not demonstrate this condition but can be used to rule out other pathologic processes such as neoplasia. 

Describes the normal concave curvature of the lumbar spine and an abnormal or exaggerated concave lumbar curvature. This condition may result from pregnancy, obesity, poor posture, rickets or tuberculosis of the spine. A lateral projection of the spine will best demonstrate the extent of lordosis. 

A congenital condition in which the posterior aspect of the vertebrae fail to develop thus exposing part of the spinal cord. This condition varies greatly in severity and occurs most often at L5. 

Involves the forward movement of one vertebra in relation to another. It is commonly due to a developmental defect in the parts interarticularis or may result from spondylolysis or severe osteoarthritis. IT is most common at L5-S1. Severe cases require a spinal fusion. 

the dissolution of a vertebra such as form aplasia of the vertebral arch and separation of the pars interarticularis of the vertebra. On the oblique projection of the neck of the Scottie dog appears broken. ITs is most common at L4 or L5.