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Correlation between radiographic measures of acetabular morphology with 3D femoral head coverage in patients with acetabular retroversion.

Hansen BJ, Harris MD, Anderson LA, Peters CL, Weiss JA, Anderson AE - Acta Orthop (2012)

Bottom Line: The acetabular angle was similar between groups.Acetabular retroversion was associated with a slight but statistically significant increase in anterior acetabular coverage, especially in the anterolateral region.We found that a number of 2D radiographic measures of acetabular morphology were correlated with 3D model-based measures of total and regional femoral head coverage.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedics, University of Utah, Salt Lake City, UT, USA.

ABSTRACT

Background and purpose: Acetabular retroversion may result in anterior acetabular over-coverage and posterior deficiency. It is unclear how standard radiographic measures of retroversion relate to measurements from 3D models, generated from volumetric CT data. We sought to: (1) compare 2D radiographic measurements between patients with acetabular retroversion and normal control subjects, (2) compare 3D measurements of total and regional femoral head coverage between patients and controls, and (3) quantify relationships between radiographic measurements of acetabular retroversion to total and regional coverage of the femoral head.

Patients and methods: For 16 patients and 18 controls we measured the extrusion index, crossover ratio, acetabular angle, acetabular index, lateral center edge angle, and a new measurement termed the "posterior wall distance". 3D femoral coverage was determined from volumetric CT data using objectively defined acetabular rim projections, head-neck junctions, and 4 anatomic regions. For radiographic measurements, intra-observer and inter-observer reliabilities were evaluated and associations between 2D radiographic and 3D model-based measures were determined.

Results: Compared to control subjects, patients with acetabular retroversion had a negative posterior wall distance, increased extrusion index, and smaller lateral center edge angle. Differences in the acetabular index between groups approached statistical significance. The acetabular angle was similar between groups. Acetabular retroversion was associated with a slight but statistically significant increase in anterior acetabular coverage, especially in the anterolateral region. Retroverted hips had substantially less posterior coverage, especially in the posterolateral region.

Interpretation: We found that a number of 2D radiographic measures of acetabular morphology were correlated with 3D model-based measures of total and regional femoral head coverage. These correlations may be used to assist in the diagnosis of retroversion and for preoperative planning.

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Comparisons of coverage between controls (solid) and subjects with acetabular retroversion (hatched), overall and by regions. Error bars represent SD. TC: total coverage; Ant: anterior coverage; Post: posterior coverage; ALC: anterolateral coverage; AMC: anteromedial coverage; PLC: posterolateral coverage; PMC: posteromedial coverage.
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Figure 3: Comparisons of coverage between controls (solid) and subjects with acetabular retroversion (hatched), overall and by regions. Error bars represent SD. TC: total coverage; Ant: anterior coverage; Post: posterior coverage; ALC: anterolateral coverage; AMC: anteromedial coverage; PLC: posterolateral coverage; PMC: posteromedial coverage.

Mentions: Patients had significantly less total coverage (50%, SD 4.6) than control subjects (58%, SD 4.4) (p < 0.001) (Figure 3). Patients also had slightly, but significantly greater anterior coverage (41%, SD 9.2) than the control subjects (35%, SD 7.2) (p = 0.03). Posterior coverage in patients was substantially and significantly less (61%, SD 7.1) than in control subjects (80%, SD 6.1) (p < 0.001). There were significant differences in AMC, PLC, and PMC between groups (Figure 3). Specifically, AMC was greater in the patient group whereas PLC and PMC were reduced. The greatest difference between groups was for PLC, where coverage for the patients (26%, SD 12.) was substantially less than for the controls (66%, SD 16). There were no significant differences in ALC between groups.


Correlation between radiographic measures of acetabular morphology with 3D femoral head coverage in patients with acetabular retroversion.

Hansen BJ, Harris MD, Anderson LA, Peters CL, Weiss JA, Anderson AE - Acta Orthop (2012)

Comparisons of coverage between controls (solid) and subjects with acetabular retroversion (hatched), overall and by regions. Error bars represent SD. TC: total coverage; Ant: anterior coverage; Post: posterior coverage; ALC: anterolateral coverage; AMC: anteromedial coverage; PLC: posterolateral coverage; PMC: posteromedial coverage.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3369147&req=5

Figure 3: Comparisons of coverage between controls (solid) and subjects with acetabular retroversion (hatched), overall and by regions. Error bars represent SD. TC: total coverage; Ant: anterior coverage; Post: posterior coverage; ALC: anterolateral coverage; AMC: anteromedial coverage; PLC: posterolateral coverage; PMC: posteromedial coverage.
Mentions: Patients had significantly less total coverage (50%, SD 4.6) than control subjects (58%, SD 4.4) (p < 0.001) (Figure 3). Patients also had slightly, but significantly greater anterior coverage (41%, SD 9.2) than the control subjects (35%, SD 7.2) (p = 0.03). Posterior coverage in patients was substantially and significantly less (61%, SD 7.1) than in control subjects (80%, SD 6.1) (p < 0.001). There were significant differences in AMC, PLC, and PMC between groups (Figure 3). Specifically, AMC was greater in the patient group whereas PLC and PMC were reduced. The greatest difference between groups was for PLC, where coverage for the patients (26%, SD 12.) was substantially less than for the controls (66%, SD 16). There were no significant differences in ALC between groups.

Bottom Line: The acetabular angle was similar between groups.Acetabular retroversion was associated with a slight but statistically significant increase in anterior acetabular coverage, especially in the anterolateral region.We found that a number of 2D radiographic measures of acetabular morphology were correlated with 3D model-based measures of total and regional femoral head coverage.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedics, University of Utah, Salt Lake City, UT, USA.

ABSTRACT

Background and purpose: Acetabular retroversion may result in anterior acetabular over-coverage and posterior deficiency. It is unclear how standard radiographic measures of retroversion relate to measurements from 3D models, generated from volumetric CT data. We sought to: (1) compare 2D radiographic measurements between patients with acetabular retroversion and normal control subjects, (2) compare 3D measurements of total and regional femoral head coverage between patients and controls, and (3) quantify relationships between radiographic measurements of acetabular retroversion to total and regional coverage of the femoral head.

Patients and methods: For 16 patients and 18 controls we measured the extrusion index, crossover ratio, acetabular angle, acetabular index, lateral center edge angle, and a new measurement termed the "posterior wall distance". 3D femoral coverage was determined from volumetric CT data using objectively defined acetabular rim projections, head-neck junctions, and 4 anatomic regions. For radiographic measurements, intra-observer and inter-observer reliabilities were evaluated and associations between 2D radiographic and 3D model-based measures were determined.

Results: Compared to control subjects, patients with acetabular retroversion had a negative posterior wall distance, increased extrusion index, and smaller lateral center edge angle. Differences in the acetabular index between groups approached statistical significance. The acetabular angle was similar between groups. Acetabular retroversion was associated with a slight but statistically significant increase in anterior acetabular coverage, especially in the anterolateral region. Retroverted hips had substantially less posterior coverage, especially in the posterolateral region.

Interpretation: We found that a number of 2D radiographic measures of acetabular morphology were correlated with 3D model-based measures of total and regional femoral head coverage. These correlations may be used to assist in the diagnosis of retroversion and for preoperative planning.

Show MeSH