Prevalence of abnormal sternal angles in a Kenyan population

Abstract

Abnormal sternal angles are unique anatomical variations of major clinical significance. For instance, misplaced sternal angles may cause inaccurate numbering of ribs and thus complicate intercostal nerve blocks and needle thoracostomies. They are also associated with increased risk of sternal fracture in blunt chest trauma. Additional sternal symphyses can be misinterpreted as fracture or lytic lesion in cross-sectional imaging of the sternum. These variations are rarely reported in Africans and lacking in the Kenyan population. We therefore aimed to determine the prevalence of abnormal sternal angles in a Kenyan population. 80 cadaveric adult sterna were studied at the Department of Anatomy, University of Nairobi, after ethical approval. The size of the angle was measured using a sliding protractor (CCKL, U.K). Results were analyzed by SPSS 18.0. The sternal angle was located at the level of the third costal notch in 7 cases (8.8%). It was un-ridged in 8 cases (10%). The angle measured 161.7° ± 4.7 in males and 159.9° ± 4.9 in females (p=0.165). In 9 cases (11.25%), the angle measured less than 150°. An additional sternal symphysis was present in 6 specimens (7.5%). Over 35% of sternal angles in Kenyans showed an abnormality in location, palpability or size. These variations may influence intercostal nerve blocks, interpretation of sternal images and evaluation of chest trauma. Further research is needed to correlate these findings.