In the literature, the hip is near-ubiquitously described as a mechanical ball-and-socket joint. This implies purely rotational motion as well as sphere-on-sphere contact geometry. However, previous works, by several authors, have quantitatively demonstrated asphericity of the articular hip surfaces in a variety of populations. This in turn implies the true kinematics of the hip joint may be more complex than purely rotational motion. Previously, general ellipsoidal shapes have been used to model the articular surface of the acetabulii of dysplastic hips. This work aims to orient the major axis of these ellipsoids with respect to the anterior pelvic plane (APP). The source data for this study were CT segmentations done in routine preparation for computer-assisted periacetabular osteotomy (PAO) procedures. Seventeen patients, aged 3510 years, were included in this study. Segmentations were performed manually by skilled technicians using Mimics (Materialize, Belgium) and saved as triangulated surface meshes. These segmentations were manually processed using Magics (Materialize, Belgium) to isolate the acetabulum, removing any non-articular features such as the acetabular ridge and notch, as well as any segmentation artefacts. The vertices of this processed mesh were extracted, and fit to general ellipsoids using Markovskys Adjusted Least Squares (ALS) algorithm. The APP was defined by the left and right anterior superior iliac spines (ASIS) and the midpoint of the pubic tubercles, with the ASIS forming the mediolateral axis. Landmarks were manually chosen mesh vertices, chosen from the approximate centre of the anatomical landmark. Orthogonal projections of the primary axis of the ellipsoid of best fit were examined in the APP and the two perpendicular planes (pseudo-axial and sagittal).Purpose
Method
Prospective randomized intervention trial to determine whether patients undergoing rotating platform total knee arthroplasty have better clinical outcomes at two years when compared to patients receiving fixed bearing total knee arthroplasty as measured by the WOMAC, SF-36 and Knee Society (KSS) scores. 67 consecutive patients (33 males and 34 females; average age 66 years) were randomized into either receiving a DePuy Sigma rotating platform (RP) total knee arthroplasty (29 patients) or a DePuy Sigma fixed bearing (FB) total knee arthroplasty (38 patients). Inclusion criteria included patients between the ages of 45–75 undergoing single-sided total knee arthoplasty for clinically significant osteoarthritic degeneration. Pain, disability and well-being were assessed using the WOMAC, KSS, and SF-36 preoperatively and at 6 months, 1 year and 2 years post-operatively. In addition, intraoperative measures were collected. Pre-operative radiographs were analyzed using the Kellgren and Lawrence Score, modified Scotts Scoring and mechanical axis. Post-operative radiographs were collected at 1 and 2 years and analyzed to identify evidence of prosthetic loosening, implant positioning and limb alignment.Purpose
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