Paper #I-1

STUDY OF THE LESSER TROCHANTER AS INDICATOR OF PROXIMAL FEMORAL ROTATION:  FOR APPLICATION TO FEMORAL FRACTURE REDUCTION

Ted V. Tufescu, MD

Saskatoon, SK

Objective

To determine relationship of lesser trochanter size and femoral rotation and apply it to guide femur fracture rotational alignment.

Design

Cadaveric femur model and retrospective clinical radiograph analysis.

Intervention

23 cadaveric femurs were mounted on a rotating platform and radiographed at 10° intervals referenced from the transepicondylar axis. The lesser trochanter was measured. Results were applied to 39 femur radiographs with fractures at various levels.

Results

A linear relationship was found between the lesser trochanter and femoral rotation, described by: Rotation = _20.93 + 127.29 _ Lesser Trochanter Index, with an r² value of 0.78. Predicted proximal fragment rotation in 39 femur fracture radiographs was related to level of fracture(p < 0.05). Mean external rotation was 33.5°(sd 5.3), 23.5°(sd 7.9) and 11.7°(sd 11.3) for proximal, middle and distal third fractures.

Conclusions

The lesser trochanter is useful in femur fracture rotational alignment. One possible reduction technique requires application of the regression equation to an intraoperative hip radiograph to determine necessary external rotation for distal fragment reduction. A second simpler and likely less accurate technique requires external rotation of the distal fragment 33.5°, 23.5° and 11.7° depending on fracture level. Both techniques are currently being studied in a clinical trial.