Refine
Document Type
- Article (3)
Language
- English (3)
Has Fulltext
- no (3)
Is part of the Bibliography
- no (3)
Keywords
- Combined anteversion (2)
- NAVIGATION (2)
- Outcome (2)
- ACETABULAR COMPONENT ORIENTATION (1)
- ANTEVERSION (1)
- Bewegungsanalyse (1)
- COMPONENT VERSION (1)
- CUP (1)
- FREE RANGE (1)
- Funktionelle Anatomie (1)
Institute
Begutachtungsstatus
- peer-reviewed (2)
Different target areas within the concept of combined cup and stem anteversion have been published for total hip arthroplasty (THA). We asked whether component positioning according to eight standard combined anteversion rules is associated with (1) more physiological gait patterns, (2) higher improvement of gait variables and (3) better clinical outcome after THA.In a prospective clinical study, 60 patients received cementless THA through an anterolateral MIS approach in a lateral decubitus position. Six weeks postoperatively, implant position was analysed using 3D-CT by an independent external institute. Preoperatively, six and 12 months postoperatively range of motion, normalized walking speed and hip flexion symmetry index were measured using 3D motion-capture gait analysis. Patient-related outcome measures (HHS, HOOS, EQ-5D) were obtained by an observer blinded to 3D-CT results. Eight combined anteversion definitions and Lewinnek's "safe zone" were evaluated regarding their impact on gait patterns and clinical outcome.Combined cup and stem anteversion according to standard combined anteversion definitions as well as cup placement within Lewinnek's "safe zone" did not influence range of motion, normalized walking speed and/or hip flexion symmetry index six and 12 months after THA. Similarly, increase of gait parameters within the first year after THA was comparable between all eight combined anteversion rules. Clinical outcome measures like HHS, HOOS and EQ-5D did not show any benefit for either of the combined anteversion definitions.Standard combined cup and stem anteversion rules do not improve postoperative outcome as measured by gait analysis and clinical scores within one year after THA.
In this prospective study of 135 patients undergoing cementless total hip arthroplasty (THA) we asked whether six current definitions of combined anteversion prevent impingement and increase postoperative patient individual impingement-free range-of-motion (ROM). Implant position was measured by an independent, external institute on 3D-CT performed six weeks post-operatively. Post-operative ROM was calculated using a CT-based algorithm detecting osseous and/or prosthetic impingement by virtual hip movement. Additionally, clinical ROM was evaluated pre-operatively and one-year post-operatively by a blinded observer. Combined component position of cup and stem according to the definitions of Ranawat, Widmer, Dorr, Hisatome and Yoshimine inhibited prosthetic impingement in over 90 %, while combined osseous and prosthetic impingement still occurred in over 40 % of the cases. The recommendations by Jolles, Widmer, Dorr, Yoshimine and Hisatome enabled higher flexion (p aecurrency sign 0.001) and internal rotation (p aecurrency sign 0.006). Clinically, anteversion rules of Widmer and Yoshimine provided one-year post-operatively statistically but not clinically relevant higher internal rotation (p aecurrency sign0.034). Standard rules of combined anteversion detect prosthetic but fail to prevent combined osseous and prosthetic impingement in THA. Future models will have to account for the patient-individual anatomic situation to ensure impingement-free ROM.
Correction of Pelvic Tilt and Pelvic Rotation in Cup Measurement after THA ? An Experimental Study
(2017)
Purpose Accurate assessment of cup orientation on postoperative pelvic radiographs is essential for evaluating outcome after THA. Here, we present a novel method for correcting measurement inaccuracies due to pelvic tilt and rotation. Method In an experimental setting, a cup was implanted into a dummy pelvis, and its final position was verified via CT. To show the effect of pelvic tilt and rotation on cup position, the dummy was fixed to a rack to achieve a tilt between +15 degrees anterior and -15 degrees posterior and 0 degrees to 20 degrees rotation to the contralateral side. According to Murray's definitions of anteversion and inclination, we created a novel corrective procedure to measure cup position in the pelvic reference frame (anterior pelvic plane) to compensate measurement errors due to pelvic tilt and rotation. Results The cup anteversion measured on CT was 23.3 degrees; on AP pelvic radiographs, however, variations in pelvic tilt (+/- 15 degrees) resulted in anteversion angles between 11.0 degrees and 36.2 degrees (mean error 8.3 degrees +/- 3.9 degrees). The cup inclination was 34.1 degrees on CT and ranged between 31.0 degrees and 38.7 degrees (m.e. 2.3 degrees +/- 1.5 degrees) on radiographs. Pelvic rotation between 0 degrees and 20 degrees showed high variation in radiographic anteversion (21.2 degrees-31.2 degrees, m.e. 6.0 degrees +/- 3.1 degrees) and inclination (34.1 degrees-27.2 degrees, m.e. 3.4 degrees +/- 2.5 degrees). Our novel correction algorithm for pelvic tilt reduced the mean error in anteversion measurements to 0.6 degrees +/- 0.2 degrees and in inclination measurements to 0.7 degrees (SD +/- 0.2). Similarly, the mean error due to pelvic rotation was reduced to 0.4 degrees +/- 0.4 degrees for anteversion and to 1.3 degrees +/- 0.8 for inclination. Conclusion Pelvic tilt and pelvic rotation may lead to misinterpretation of cup position on anteroposterior pelvic radiographs. Mathematical correction concepts have the potential to significantly reduce these errors, and could be implemented in future radiological software tools.