Abstracts Posters SICOT-SOF meeting Gothenburg 2010 _2_

Poster
Topic: Trauma - Hip
Abstract number: 26361
PROPENSITY FOR HIP DISLOCATION IN GAIT LOADING VERSUS SIT-TO-
STAND MANEUVERS: IMPLICATIONS FOR REDEFINING THE WEIGHT
BEARING DOME OF THE ACETABULUM DURING ACTIVITIES OF DAILY
LIVING.
Amir MATITYAHU, Erik MCDONALD, Jennifer BUCKLEY, Meir MARMOR
Orthopaedic Trauma Institute, San Francisco, CA (UNITED STATES)
A large percentage of the day is spent in a sitting position. We compared hip joint
stability during single leg stance (SLS) and sit to stand (STS) maneuvers using a
transverse acetabular fracture model.Methods: Seven side randomized fresh frozen
cadaveric hemi-pelvic specimens with proximal femurs were dissected of all soft
tissues except for the acetabular labrum. Transverse acetabular fractures were
created in 5 mm increments from distal to proximal. The roof arc angle (RAA) and
reduction of articular surface area (RAS) were measured. A 1200 N load was applied
to the acetabulum simulating the STS cycle (15° abd uction, 90° flexion) and SLS (15
° abduction, 0° flexion). Results: The average RAA needed to dislocate in the SLS
position was 71.9° in the iliac oblique (IO), 46.1° in the anterior-posterior (AP), and
25.2° in the obturator oblique (OO) X-ray. The aver age RAA needed to dislocate in
the STS position was 101.4° in IO, 90.9° in AP, and 67.3° in OO X-ray views. There
was a significant difference in the RAAs between the SLS and STS in all
Roentgenograms (p