Radiologic measurement of lesser trochanter and its clinical significance in Chinese

Femoral fracture is a major cause of morbidity and mortality in elderly persons. Surgery, the main choice of treatment of femoral fracture, may result in some complications severely affecting patients’ daily activities due to femoral malalignment. The lesser trochanter is an important anatomical structure of the femur which could be used as an anatomical landmark during and after operation to evaluate femoral alignment. To predict femoral rotational malalignment during surgery, the relationship between the height and width of the lesser trochanter and femoral rotation at different angles was investigated.

Fifty healthy adult volunteers (25 men and 25 women) were enrolled in this study and a total of 900 radiographs of proximal femurs were taken in the following positions: neutral position, 5°, 10°, 15°, and 20° internal rotation, and 5°, 10°, 15°, and 20° external rotation, respectively. The cranio-caudal and transverse diameters of the lesser trochanter were obtained on a PACS Workstation.

The height and width of the lesser trochanter increased with external rotation and decreased with internal rotation and the values showed statistical significance between different positions or different genders. Between 20° of internal rotation to 20° of external rotation, the mean height increased from 0.58 cm to 1.23 cm in men and from 0.44 cm to 1.19 cm in women. The corresponding mean values for width were from 2.53 cm to 4.44 cm in men, and from 2.08 cm to 3.86 cm in women, respectively. The height and width of the lesser trochanter were both highly correlated to the position of femur and the linear relationship was established approximately. The morphological alteration of lesser trochanter also changed obviously when the femurs rotated.

The height and width of the lesser trochanter is linearly related to femoral rotation and could be used as a reference for prevention of femoral malalignment during surgery.