Artikel
Increased Femoral Antetorsion is a new cause for Extraarticular Ischiofemoral Hip Impingement in a 3D CT Impingement Simulation Study
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Autoren
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Till Lerch
- Inselspital Bern, University Hospital Bern, Department of orthopedic surgery and traumatology, University of Bern, Bern, Switzerland
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Florian Schmaranzer
- Inselspital Bern, University Hospital Bern, Department of orthopedic surgery and traumatology, University of Bern, Bern, Switzerland
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Simon Steppacher
- Inselspital Bern, University Hospital Bern, Department of orthopedic surgery and traumatology, University of Bern, Bern, Switzerland
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Guoyan Zheng
- ISTB, Institute for Surgical Technologies and Biomechanics, University of Bern, Bern, Switzerland
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Moritz Tannast
- Inselspital Bern, University Hospital Bern, Department of orthopedic surgery and traumatology, University of Bern, Bern, Switzerland
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Klaus Siebenrock
- Inselspital Bern, University Hospital Bern, Department of orthopedic surgery and traumatology, University of Bern, Bern, Switzerland
| Veröffentlicht: | 22. Oktober 2019 |
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Gliederung
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Objectives: Femoroacetabular Impingement (FAI) can be caused by cam or pincer deformities. Abnormal femoral torsion could be a new cause for FAI. In valgus hips with increased femoral torsion (FT) a posterior extraarticular ischiofemoral hip impingement has been detected. Hips with increased FT can be combined with and without valgus deformity and can present clinically with a lack of external rotation and extension and a positive posterior impingement test or FABER test.
Research questions: We asked whether (1) the range of motion (ROM); (2) the location of anterior and posterior osseous collision zones; (3) and the prevalence of posterior extraarticular impingement differ between hips with isolated increased FT, hips with combined increased FT and increased acetabular version (AV); and valgus hips with increased FT and increased AV.
Methods: An IRB approved, 3D Impingement simulation study involving 52 hips was performed. Reconstruction of patient-specific 3D models based on 3D CT scans of 52 hips with symptomatic posterior FAI were evaluated using specific software. These included 21 hips with isolated increased FT (FT>25°), 22 hips with combined increased FT and AV (>25°) and 9 valgus hips with increased FT and AV. Validated three-dimensional collision detection software was used to quantify the simulated ROM and the location of impingement on the acetabular and femoral sides.
Results: (1) Valgus hips with combined increased FT and AV showed decreased flexion (p<0.001) and external rotation in 90° of flexion (p=0.011), whereas internal rotation in 0° of flexion was increased (p=0.003) compared to hips with increased FT and AV. Internal rotation in 120° of flexion was decreased in valgus hips with increased FT and AV compared to hips with increased FT and AV. (2)Location of acetabular and femoral posterior impingement zones differed significantly (p<0.001) between hips with increased FT and AV and hips with valgus, increased FT and AV. (3) 90% of acetabular and femoral impingement zones were located posterior extraarticular in hips with increased FT and AV, that was significantly (p<0.001) increased compared to 60% of valgus hips with increased FT and AV.
Conclusions: Hips with combined increased FT and AV and hips with isolated increased FT exhibit a novel cause for posterior extraarticular FAI located between the ischium and the lesser trochanter. Treatment with derotational femoral osteotomy and hip arthroscopy or open FAI surgery could overcome this problem. Increased FT seems to be a novel cause for posterior extraarticular ischiofemoral hip impingement and potential anterior hip instability.
