Relationship between radiographic measurements of reconstructed hip joint position and the Trendelenburg sign

Abstract

We evaluated 60 limbs, including 34 primary total hip arthroplasties in 30 patients (mean age, 56 years) at a minimum of 2 years postoperatively. Femoral offset ratio (%FO) was calculated by dividing the femoral offset by the distance between the centers of the bilateral femoral heads on radiographs. The tilt angle of the pelvis by the Trendelenburg test was measured using the magnetic sensor system. In the limbs having a negative Trendelenburg sign after reconstruction, the %FO averaged 20.1% (range, 14.7% to 24.7%), and the tilt angle of the pelvis averaged +0.8 degrees (range, -1.0 degrees to +5.0 degrees ). The tilt angle of the pelvis correlated positively with %FO (P=.0160, r=0.407). The reconstructed hip joint position is crucial to improve hip abductor function.