Radiographic assessment of sacral hiatus anatomy with backache.

OBJECTIVES: To determine hiatal variations in cases of backache and controls on radiographs and association of age groups with hiatal parameters in patients with backache versus normal individuals.

METHODS: This case control study on 178 patients (89 cases and 89 controls), aged from 18-65 years, selected by non-probability convenience sampling was conducted at Radiology Department of PNS Shifa Hospital, Karachi over six months.The sacral hiatus was identified on lumbosacral spine radiographs. Both metric and non-metric parameters of hiatus with respect to sacral vertebra were noted and compared between the groups.

RESULTS: Inverted "U" was the most common type observed in cases with base of hiatus at S5 level. Comparison of hiatal shape among different age groups showed inverted "U" and inverted "V" types among all age groups. Hiatal anteroposterior diameter and width were greatest in 36-45-year age group, and it was longest in 46-55-year age group. Determination of relationship between sacral hiatal parameters and incidence of low back pain showed positive association of inverted "U" and "M" shapes with back pain. Increased risk of back pain was observed with high apex (first sacral vertebra (S1)).

CONCLUSION: Strong positive correlation was determined with inverted "U" and "M" shapes, and level of apex at S1 with low backache.