Fixation method does not affect restoration of rotation center in hip replacements: A single-site retrospective study

Abstract

BackgroundAseptic loosening is one of the greatest problems in hip replacement surgery. The rotation center of the hip is believed to influence the longevity of fixation. The aim of this study was to compare the influence of cemented and cementless cup fixation techniques on the position of the center of rotation because cemented cup fixation requires the removal of more bone for solid fixation than the cementless technique.MethodsWe retrospectively compared pre- and post-operative positions of the hip rotation center in 25 and 68 patients who underwent artificial hip replacements in our department in 2007 using cemented or cementless cup fixation, respectively, with digital radiographic image analysis.ResultsThe mean horizontal and vertical distances between the rotation center and the acetabular teardrop were compared in radiographic images taken pre- and post-operatively. The mean horizontal difference was −2.63 mm (range: -11.00 mm to 10.46 mm, standard deviation 4.23 mm) for patients who underwent cementless fixation, and −2.84 mm (range: -10.87 to 5.30 mm, standard deviation 4.59 mm) for patients who underwent cemented fixation. The mean vertical difference was 0.60 mm (range: -20.15 mm to 10.00 mm, standard deviation 3.93 mm) and 0.41 mm (range: -9.26 mm to 6.54 mm, standard deviation 3.58 mm) for the cementless and cemented fixation groups, respectively. The two fixation techniques had no significant difference on the position of the hip rotation center in the 93 patients in this study.ConclusionsThe hip rotation center was similarly restored using either the cemented or cementless fixation techniques in this patient cohort, indicating that the fixation technique itself does not interfere with the position of the center of rotation. To completely answer this question further studies with more patients are needed.

The Transverse Mechanical Axis of the Pelvis for Post-Operative Evaluation of Total Hip Arthroplasty

“…Boudriot et al found that the intersection between Koehler's line (ilioischial line) and a line between the upper rims of the two obturator foramens (UOF) is a reliable landmark to determine the anatomic hip center [32]. Wegner et al used a line drawn through the top of the obturator foramen (UOF) to replace the IT line when the base of the teardrop was not clearly visible [33]. Our multiple measurements by different observers also demonstrate that the UOF exhibits accuracy no less than the IT line in both overall data and measurement results in the subdivided subgroups.…”

High Variability of Acetabular Offset in Primary Hip Osteoarthritis Influences Acetabular Reaming—A Computed Tomography–Based Anatomic Study

“…Thirdly, we assumed that all cups were hemispherical in nature, although certain cup designs (e.g resurfacings) are not hemispherical or have a flattened pole area [32]. Fourthly, we only simulated impaction of an uncemented hemispherical cup rather than cemented components; however, Wegner et al [33] showed no difference in the ability to restore COR with different acetabular component fixation modes. Lastly, the present cohort comprised only patients with primary OA so the findings may not be applicable to patients with secondary OA hips.…”

Reliability of measures used in radiographic evaluation of the adult hip

“…Furthermore, reliability and agreement to evaluate measures in a longitudinal fashion was not studied. A relocation of COR by less than 5 mm in any direction horizontally or vertically has been described as optional by Wegner et al [19]. The same boundaries of 5-mm shortening or lengthening of the femoral offset have been described as the border defining short, normal, or increased femoral offset postoperatively after hip prosthesis [20,21].…”