Till D Lerch1, Mathias Siegfried1, Florian Schmaranzer1,2, Christiane S Leibold1, Corinne A Zurmühle1, Markus S Hanke1, Michael K Ryan3, Simon D Steppacher1, Klaus A Siebenrock1, Moritz Tannast1,4. 1. Department of Orthopaedic Surgery, Inselspital, University of Bern, Bern, Switzerland. 2. University Institute of Diagnostic, Interventional and Paediatric Radiology, University of Bern, Inselspital, Bern, Switzerland. 3. American Sports Medicine Institute, Andrews Orthopaedic and Sports Medicine Center, Birmingham, Alabama, USA. 4. Department of Orthopaedic Surgery and Traumatology, Fribourg Cantonal Hospital, University of Fribourg, Fribourg, Switzerland.
Abstract
BACKGROUND: Diagnosis and surgical treatment of hips with different types of pincer femoroacetabular impingement (FAI), such as protrusio acetabuli and acetabular retroversion, remain controversial because actual 3-dimensional (3D) acetabular coverage and location of impingement cannot be studied via standard 2-dimensional imaging. It remains unclear whether pincer hips exhibit intra- or extra-articular FAI. PURPOSE: (1) To determine the 3D femoral head coverage in these subgroups of pincer FAI, (2) determine the impingement-free range of motion (ROM) through use of osseous models based on 3D-computed tomography (CT) scans, and (3) determine the osseous intra-and extra-articular 3D impingement zones by use of 3D impingement simulation. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: This is a retrospective, comparative, controlled study involving 70 hips in 50 patients. There were 24 patients (44 hips) with symptomatic pincer-type or mixed-type FAI and 26 patients (26 hips) with normal hips. Surface models based on 3D-CT scans were reconstructed and compared for hips with acetabular retroversion (30 hips), hips with protrusio acetabuli (14 hips), and normal asymptomatic hips (26 hips). Impingement-free ROM and location of impingement were determined for all hips through use of validated 3D collision detection software based on CT-based 3D models. No abnormal morphologic features of the anterior iliac inferior spine were detected. RESULTS: (1) Mean total femoral head coverage was significantly (P < .001) increased in hips with protrusio acetabuli (92% ± 7%) and acetabular retroversion (71% ± 5%) compared with normal hips (66% ± 6%). (2) Mean flexion was significantly (P < .001) decreased in hips with protrusio acetabuli (104°± 9°) and acetabular retroversion (116°± 6°) compared with normal hips (125°± 13°). Mean internal rotation in 90° of flexion was significantly (P < .001) decreased in hips with protrusio acetabuli (16°± 12°) compared with normal hips (35°± 13°). (3) The prevalence of extra-articular subspine impingement was significantly (P < .001) higher in hips with acetabular retroversion (87%) compared with hips with protrusio acetabuli (14%) and normal hips (0%) and was combined with intra-articular impingement. The location of anterior impingement differed significantly (P < .001) between hips with protrusio acetabuli and normal hips. CONCLUSION: Using CT-based 3D hip models, we found that hips with pincer-type and mixed-type FAI have significantly larger femoral head coverage and different osseous ROM and location of impingement compared with normal hips. Additionally, intra- and extra-articular subspine impingement was detected predominantly in hips with acetabular retroversion. Acetabular rim trimming during hip arthroscopy or open surgical hip dislocation should be performed with caution for these hips. Patient-specific analysis of location of impingement using 3D-CT could theoretically improve diagnosis and planning of surgical treatment.
BACKGROUND: Diagnosis and surgical treatment of hips with different types of pincer femoroacetabular impingement (FAI), such as protrusio acetabuli and acetabular retroversion, remain controversial because actual 3-dimensional (3D) acetabular coverage and location of impingement cannot be studied via standard 2-dimensional imaging. It remains unclear whether pincer hips exhibit intra- or extra-articular FAI. PURPOSE: (1) To determine the 3D femoral head coverage in these subgroups of pincer FAI, (2) determine the impingement-free range of motion (ROM) through use of osseous models based on 3D-computed tomography (CT) scans, and (3) determine the osseous intra-and extra-articular 3D impingement zones by use of 3D impingement simulation. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: This is a retrospective, comparative, controlled study involving 70 hips in 50 patients. There were 24 patients (44 hips) with symptomatic pincer-type or mixed-type FAI and 26 patients (26 hips) with normal hips. Surface models based on 3D-CT scans were reconstructed and compared for hips with acetabular retroversion (30 hips), hips with protrusio acetabuli (14 hips), and normal asymptomatic hips (26 hips). Impingement-free ROM and location of impingement were determined for all hips through use of validated 3D collision detection software based on CT-based 3D models. No abnormal morphologic features of the anterior iliac inferior spine were detected. RESULTS: (1) Mean total femoral head coverage was significantly (P < .001) increased in hips with protrusio acetabuli (92% ± 7%) and acetabular retroversion (71% ± 5%) compared with normal hips (66% ± 6%). (2) Mean flexion was significantly (P < .001) decreased in hips with protrusio acetabuli (104°± 9°) and acetabular retroversion (116°± 6°) compared with normal hips (125°± 13°). Mean internal rotation in 90° of flexion was significantly (P < .001) decreased in hips with protrusio acetabuli (16°± 12°) compared with normal hips (35°± 13°). (3) The prevalence of extra-articular subspine impingement was significantly (P < .001) higher in hips with acetabular retroversion (87%) compared with hips with protrusio acetabuli (14%) and normal hips (0%) and was combined with intra-articular impingement. The location of anterior impingement differed significantly (P < .001) between hips with protrusio acetabuli and normal hips. CONCLUSION: Using CT-based 3D hip models, we found that hips with pincer-type and mixed-type FAI have significantly larger femoral head coverage and different osseous ROM and location of impingement compared with normal hips. Additionally, intra- and extra-articular subspine impingement was detected predominantly in hips with acetabular retroversion. Acetabular rim trimming during hip arthroscopy or open surgical hip dislocation should be performed with caution for these hips. Patient-specific analysis of location of impingement using 3D-CT could theoretically improve diagnosis and planning of surgical treatment.
Entities:
Keywords:
FAI; acetabular retroversion; femoroacetabular impingement; hip arthroscopy; hip impingement; protrusio acetabuli
Authors: Till D Lerch; Malin K Meier; Adam Boschung; Simon D Steppacher; Klaus A Siebenrock; Moritz Tannast; Florian Schmaranzer Journal: Eur J Radiol Open Date: 2022-02-25
Authors: Guodong Zeng; Celia Degonda; Adam Boschung; Florian Schmaranzer; Nicolas Gerber; Klaus A Siebenrock; Simon D Steppacher; Moritz Tannast; Till D Lerch Journal: Orthop J Sports Med Date: 2021-11-24
Authors: Malin K Meier; Jelena Reche; Florian Schmaranzer; Hendrik von Tengg-Kobligk; Simon D Steppacher; Moritz Tannast; Eduardo N Novais; Till D Lerch Journal: Bone Jt Open Date: 2022-07
Authors: Carsten Y W Heimer; Chia H Wu; Carsten Perka; Sebastian Hardt; Friedemann Göhler; Tobias Winkler; Henrik C Bäcker Journal: J Pers Med Date: 2022-07-12
Authors: Till D Lerch; Tiziano Antioco; Malin K Meier; Adam Boschung; Markus S Hanke; Moritz Tannast; Klaus A Siebenrock; Florian Schmaranzer; Simon D Steppacher Journal: J Hip Preserv Surg Date: 2022-04-21