Introduction: Sock application is a daily task that can pose a dislocation risk to implanted hips. The aim of this study was to measure hip flexion and rotation using three seated techniques of sock application. Namely:- 1. The leg crossed in a “figure of four” technique, 2. The lean forward technique, and 3. using a specialised sock applicator (Foxy Sock Aid).

Methods: The movement of 32 hips in 16 healthy male volunteers, aged 20–43, were assessed as socks were applied using the 3 techniques listed above. Hip flexion and axial rotation were measured with a “Polhemus Fastrak” magnetic tracking system. Data was recorded from magnetic sensors attached around the subjects femur and Iliac Spine. The sensors measurement accuracy was 0.15 degrees.

Results: All measurements started with the subjects sitting with their hips in approximately 90 degrees of flexion. The mean (SD) additional flexion required for each of the 3 techniques were:- Cross leg = 57.2⁰ (13.7), Lean forward = 51.3⁰ (17.7), and Sock applicator = 11.2⁰ (7.2). Hence the sock applicator required 40.1 degrees less flexion (P< < 0.001) than the lean forward technique. The lean forward technique required 5.9 degrees less flexion (P=0.007) than the cross legged technique.

The mean (SD) peak rotations for each of the 3 techniques were:- Cross leg = 35.1⁰ (9.8) external, Lean forward = 0.1⁰ (3.8) internal, and Sock applicator = 0.8⁰ (4.0) internal.

Discussion: The sock applicator, when used correctly, requires very little hip flexion. When patients stop using the sock applicator, they should be encourage to use the lean forward technique, as this requires little axial rotation.