Determining Stability in Posterior Wall Acetabular Fractures.
OBJECTIVE
To determine if the radiographic parameters of femoral head coverage by the intact posterior wall, acetabular version, and location of the fracture or a history of dislocation were determinates of hip stability in patients with posterior wall acetabular fractures.


METHODS
Retrospective review.


METHODS
Level I trauma hospital.


METHODS
One hundred eighty-five consecutive patients with isolated unilateral posterior wall (OTA 62-A1) acetabular fractures.


METHODS
Patients underwent dynamic stress fluoroscopic examination under general anesthesia to determine hip stability.


METHODS
A number of radiographic measurements were performed, and an examination under anesthesia served as a standard to compare stable versus unstable hips.


RESULTS
Examination under anesthesia (EUA) determined 116 hips to be stable and 22 hips as unstable. Moed and Keith method of wall size measurements and cranial exit point of fracture was statistically different between stable and unstable hips. Twenty-three percent of the unstable hips had wall sizes less than 20%. Average cranial exit point of fracture from dome was 5.0 mm in the unstable group and 9.5 mm in the stable group, and fractures that extend into the dome demonstrate a statistically significant increase in hip instability.


CONCLUSIONS
Determination of hip stability can be challenging in patients with posterior wall acetabular fractures. Our data suggest that the location of the exit point of the fracture in relation to the dome of the acetabulum is a radiographic marker that can be used to aid physician in determining stability, and wall sizes less than 20% is not a reliable indicator of stability.


METHODS
Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.
*Department of Orthopaedic Surgery, Harborview Medical Center, Seattle, WA; †University of Mississippi, Jackson, MS; ‡University of Washington, Seattle, WA; §Case Western School of Medicine, Cleveland, OH; ‖Harborview Medical Center, University of Washington, Seattle, WA; ¶University of Texas, Houston, TX; and **Boston University Medical Center, Boston, MA.
Reza
R
Firoozabadi
Clay
C
Spitler
Calvin
C
Schlepp
Benjamin
B
Hamilton
Julie
J
Agel
Milton Chip
MC
Routt
Paul
P
Tornetta
D000077:Acetabulum / Q000000981:diagnostic imaging* / Q000293:injuries*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D050723:Fractures, Bone / Q000150:complications / Q000000981:diagnostic imaging*; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult