1. by Alexander P. Sah, and Daniel M. Estok
Dislocation Rate After Conversion from Hip Hemiarthroplasty to Total Hip Arthroplasty
by Alexander P. Sah, and Daniel M. Estok
J Bone Joint Surg Am
Volume 90(3):
March 1, 2008
©2008 by The Journal of Bone and Joint Surgery, Inc.

2. Abduction angle of the acetabular component (theta), defined by the angle between a horizontal line at the base of the ischia and a line parallel to the acetabular component on an anteroposterior pelvic radiograph.
Abduction angle of the acetabular component (theta), defined by the angle between a horizontal line at the base of the ischia and a line parallel to the acetabular component on an anteroposterior pelvic radiograph.
Alexander P. Sah, and Daniel M. Estok II J Bone Joint Surg Am 2008;90:
©2008 by The Journal of Bone and Joint Surgery, Inc.

3. Acetabular anteversion, defined as the angle (alpha) between a vertical line and a line parallel to the acetabular component on a shoot-through lateral radiograph of the hip.
Acetabular anteversion, defined as the angle (alpha) between a vertical line and a line parallel to the acetabular component on a shoot-through lateral radiograph of the hip.
Alexander P. Sah, and Daniel M. Estok II J Bone Joint Surg Am 2008;90:
©2008 by The Journal of Bone and Joint Surgery, Inc.

4. Bar chart showing the percentage of dislocations associated with each femoral head size used in the conversions of the hemiarthroplasties and in the first-time revisions of the total hip arthroplasties.
Bar chart showing the percentage of dislocations associated with each femoral head size used in the conversions of the hemiarthroplasties and in the first-time revisions of the total hip arthroplasties. The majority of the patients in both groups received a 28, 32, or 36-mm femoral head.
Alexander P. Sah, and Daniel M. Estok II J Bone Joint Surg Am 2008;90:
©2008 by The Journal of Bone and Joint Surgery, Inc.

5. Figs. 3-A, 3-B, and 3-C Diagrams illustrating the effects of “femoral head downsizing” with conversion from a hemiarthroplasty to a total hip replacement.
Figs. 3-A, 3-B, and 3-C Diagrams illustrating the effects of “femoral head downsizing” with conversion from a hemiarthroplasty to a total hip replacement. Fig. 3-A A large femoral head of a hemiarthroplasty has inherent stability as a result of its size. The red lines in the diagram represent the tension of the soft tissues after healing from the surgery.
Alexander P. Sah, and Daniel M. Estok II J Bone Joint Surg Am 2008;90:
©2008 by The Journal of Bone and Joint Surgery, Inc.

6. The reduction in the femoral head size after conversion surgery results in increased relative laxity of the soft tissues, which have been previously compromised by the index procedure.
The reduction in the femoral head size after conversion surgery results in increased relative laxity of the soft tissues, which have been previously compromised by the index procedure.
Alexander P. Sah, and Daniel M. Estok II J Bone Joint Surg Am 2008;90:
©2008 by The Journal of Bone and Joint Surgery, Inc.

7. Dislocation is more likely to occur with smaller head sizes, since these represent the greatest amount of femoral head downsizing in the context of compromised soft tissues.
Dislocation is more likely to occur with smaller head sizes, since these represent the greatest amount of femoral head downsizing in the context of compromised soft tissues.
Alexander P. Sah, and Daniel M. Estok II J Bone Joint Surg Am 2008;90:
©2008 by The Journal of Bone and Joint Surgery, Inc.