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S A Olson

Publications and source records attributed to S A Olson.

40 records · Page 3Linked to original sources
PubMedDate not supplied

Biomechanical evaluation of a low anterior wall fracture: correlation with the CT subchondral arc.

OBJECTIVE: To measure the effect of a simulated low anterior wall fracture of the acetabulum on load transmission in the hip joint. DESIGN: We measured the contact areas and pressure between the acetabulum and the femoral head of cadaveric pelves in three different conditions: intact, with an operatively created fracture of the anterior wall, and after anatomic reduction and internal fixation of the fracture. SETTING: Hips were loaded in simulated single-limb stance. Pressure and area measurements were made with Fuji pressure-sensitive film. SPECIMENS: Seven hip joints in seven whole pelves were tested. INTERVENTION: Anterior wall fractures were anatomically reduced and fixed. MAIN OUTCOME MEASUREMENTS: Contact area, load, and mean and maximum pressures were measured. RESULTS: Anterior wall fractures in our specimens entered the hip joint an average of 9.7 millimeters from the vertex of the acetabulum, corresponding to a 45-degree roof arc measurement. Peripheral loading seen in the intact acetabulum was disrupted after fracture. The loading pattern was not restored to preinjury levels with anatomic reduction and fixation. There was no significant change in the contact area (p = 0.43), force (p = 0.06), or mean (p = 0.57) or maximum (p = 0.20) pressures in the superior aspect of the acetabulum after creation of the anterior wall fracture. CONCLUSIONS: These results differ from those of previous studies with posterior wall acetabulum fractures, where significant increases in force and mean and maximum pressures were noted in the superior acetabulum after fracture. The lack of significant increases in superior acetabular pressures is discussed in relation to the mean computed tomographic subchondral arc of approximately ten millimeters in our specimens.

Acetabulum↗
PubMedDate not supplied

Biomechanical consequences of anterior column fracture of the acetabulum.

OBJECTIVES: To measure biomechanical consequences of a high anterior column acetabular fracture. DESIGN: A benchtop biomechanical model using quasi-static loading of the hip joint in a simulated single-leg stance. Pressure-sensitive prescale (Fuji) film was used to determine hip joint loading parameters. PARTICIPANTS: Six cadaveric hemipelvi with one hip tested in each specimen. Three right and three left hips were tested. INTERVENTION: Creation of an anterior column fracture with anatomic reduction and fixation, followed by gap malreduction/fixation, and subsequently step malreduction/fixation. MAIN OUTCOME MEASUREMENTS: Contact pressure, contact area, and load distribution throughout the hip joint in each experimental condition. RESULTS: There were significant increases in load (p<0.01) and peak pressures (p<0.01) in the superior acetabular region after gap malreduction and in peak contact pressures after step malreduction (p<0.01) as compared with the intact acetabulum. Anatomic reduction was not associated with increased mean or peak contact pressures (in any region). CONCLUSIONS: Both step and gap malreductions of a high anterior column fracture resulted in significantly increased peak contact pressures in the superior acetabular region. These biomechanical data cannot be directly extrapolated to clinical applications, but these data suggest that anatomic reduction of anterior column fracture affords the best opportunity to restore contact pressures, contact area, and load distribution within the hip to levels similar to those seen in the intact acetabulum.

Acetabulum↗