Ossification of anterior sacroiliac ligament and its clinical significance

Abstract Introduction: Sacrum articulates on either side of the innominate bones forming sacroiliac joints. The joint is strengthened by anterior sacroiliac ligament anteriorly and dorsal sacroiliac ligament posteriorly. Weight of the body is transmitted from sacrum to iliac bone mainly through sacroiliac ligaments. Sacroiliac joint becomes important while treating ankylosis and degenerative diseases in pelvis. It exhibits number of variations with age. Materials and Methods: During osteology demonstration classes of first year MBBS students of KG Medical University Lucknow, UP, India, author came across a dry male pelvis having partial ossification of anterior sacroiliac ligament connecting the sacrum and ilium in left side. Results: The right SI Joint was not ossified. Only left antero-superior part of the anterior sacroiliac ligament was ossified and rest was not ossified. The length of ossified part of ligament was 4.5 cm and remaining part of the same was 6.5 cm. On the dorsal surface, posterior sacroiliac and interosseous ligaments were not ossiied. There was no ankylosis of sacroiliac joint but the coccyx was fused with tip of sacrum. The probable cause of ossification may be genetic or more weight transmission through this ligament due to shifting of centre of gravity as a result of leaning of the body in left side on account of disease, trauma or pathological conditions. Conclusion: This Case report brings out an unreported anatomical variant of partial ossiication of anterior sacroiliac ligaments. The knowledge will be of paramount importance to clinicians for pain, to radiologists for misinterpretation of radiographs and to anatomists for new variant.