Femoral offset is underestimated on anteroposterior radiographs of the pelvis but accurately assessed on anteroposterior radiographs of the hip
ABSTRACT The aim of this retrospective cohort study was to identify any difference in femoral offset as measured on pre-operative anteroposterior (AP) radiographs of the pelvis, AP radiographs of the hip and corresponding CT scans in a consecutive series of 100 patients with primary end-stage osteoarthritis of the hip (43 men and 57 women with a mean age of 61 years (45 to 74) and a mean body mass index of 28 kg/m(2) (20 to 45)). Patients were positioned according to a standardised protocol to achieve reproducible projection and all images were calibrated. Inter- and intra-observer reliability was evaluated and agreement between methods was assessed using Bland-Altman plots. In the entire cohort, the mean femoral offset was 39.0 mm (95% confidence interval (CI) 37.4 to 40.6) on radiographs of the pelvis, 44.0 mm (95% CI 42.4 to 45.6) on radiographs of the hip and 44.7 mm (95% CI 43.5 to 45.9) on CT scans. AP radiographs of the pelvis underestimated femoral offset by 13% when compared with CT (p < 0.001). No difference in mean femoral offset was seen between AP radiographs of the hip and CT (p = 0.191). Our results suggest that femoral offset is significantly underestimated on AP radiographs of the pelvis but can be reliably and accurately assessed on AP radiographs of the hip in patients with primary end-stage hip osteoarthritis. We, therefore, recommend that additional AP radiographs of the hip are obtained routinely for the pre-operative assessment of femoral offset when templating before total hip replacement.
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ABSTRACT: Background and purpose - Adequate restoration of femoral offset (FO) is critical for successful outcome after hip arthroplasty or fixation of hip fracture. Previous studies have identified that hip rotation influences the projected femoral offset (FOP) on plain anteroposterior (AP) radiographs, but the precise effect of rotation is unknown. Patients and methods - We developed a novel method of assessing rotation-corrected femoral offset (FORC), tested its clinical application in 222 AP hip radiographs following proximal femoral nailing, and validated it in 25 cases with corresponding computed tomography (CT) scans. Results - The mean FORC was 57 (29-93) mm, which differed significantly (p < 0.001) from the mean FOP 49 (22-65) mm and from the mean femoral offset determined by the standard method: 49 (23-66) mm. FORC correlated closely with femoral offset assessed by CT (FOCT); the Spearman correlation coefficient was 0.94 (95% CI: 0.88-0.97). The intraclass correlation coefficient for the assessment of FORC by AP hip radiographs correlating the repeated measurements of 1 observer and of 2 independent blinded observers was 1.0 and 1.0, respectively. Interpretation - Hip rotation affects the FOP on plain AP radiographs of the hip in a predictable way and should be adequately accounted for.Acta Orthopaedica 06/2014; DOI:10.3109/17453674.2014.931196 · 2.45 Impact Factor
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ABSTRACT: Purpose Component orientations and positions in total hip arthroplasty (THA) are important parameters in restoring hip function. However, measurements using plain radiographs and 2D computed tomography (CT) slices are affected by patient position during imaging. This study used 3D CT to determine whether contemporary THA restores native hip geometry. Methods Fourteen patients with unilateral THA underwent CT scan for 3D hip reconstruction. Hip models of the nonoperated side were mirrored with the implanted side to quantify the differences in hip geometry between sides. Results The study demonstrated that combined hip anteversion (sum of acetabular and femoral anteversion) and vertical hip offset significantly increased by 25.3 degrees +/- 29.3 degrees (range, -25.7 degrees to 55.9 degrees, p = 0.003) and 4.1 +/- 4.7 mm (range, -7.1 to 9.8 mm, p = 0.009) in THAs. Conclusions These data suggest that hip anatomy is not fully restored following THA compared with the contralateral native hip.International Orthopaedics 06/2014; 38(8). DOI:10.1007/s00264-014-2401-3 · 2.02 Impact Factor
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ABSTRACT: Background: Lateral patellar arthritis has been associated with poor outcomes in unicompartmental knee arthroplasty. The current study correlates intraoperative findings with MRI imaging, skyline radiographs and the presence of anterior knee pain. Methods: In 92 consecutive knees with varus arthritis, the patellofemoral compartment was assessed during surgery, on skyline radiographs and on MRI. Anterior knee pain was recorded on a visual-analog-scale. Intraoperative assessment was based on the Outerbridge grading scale. Skyline radiographs were evaluated according to the Ahlback grading scale; MRIs were assessed according to a modified Outerbridge grading scale. Results: There was an excellent correlation (r(s)=0.833; p<0.001) in the cartilage assessment of the lateral patellar facet between MRI and surgery. A good correlation (r(s)=0.664; p<0.001) was seen between Ahlback Grades and macroscopic Outerbridge Grades of the lateral patella. Ahlback Grades and MRI modified Outerbridge Grades showed a good correlation (r(s)=0.643; p<0.001) for the lateral patella. Twelve percent of knees (seven out of 60) with Ahlback Grade 0 or 1 and mild to moderate anterior knee pain had a macroscopic Outerbridge Grade of 3 on the lateral patella. None of these 60 knees had a full-thickness cartilage defect on MRI. Conclusion: Normal skyline radiographs in patients with mild to moderate anterior knee pain can rule out full-thickness cartilage defects of the lateral patellar facet as observed during surgery and on MRI. The MRI allows for the most accurate assessment of the patellofemoral joint and is warranted in all patients with radiographic abnormalities or severe anterior knee pain.The Knee 05/2014; 21(5). DOI:10.1016/j.knee.2014.05.005 · 1.70 Impact Factor