Motion study of the hip joint in extreme postures

Many causes can be at the origin of hip osteoarthritis (e.g., cam/pincer impingements), but the exact pathogenesis for idiopathic osteoarthritis has not yet been clearly delineated. The aim of the present work is to analyze the consequences of repetitive extreme hip motion on the labrum cartilage. Our hypothesis is that extreme movements can induce excessive labral deformations and lead to early arthritis. To verify this hypothesis, an optical motion capture system is used to estimate the kinematics of patient-specific hip joint, while soft tissue artifacts are reduced with an effective correction method. Subsequently, a physical simulation system is used during motion to compute accurate labral deformations and to assess the global pressure of the labrum, as well as any local pressure excess that may be physiologically damageable. Results show that peak contact pressures occur at extreme hip flexion/abduction and that the pressure distribution corresponds with radiologically observed damage zones in the labru

DANCING AS A POTENTIAL INITIATOR OF EARLY HIP OSTEOARTHRITIS

We present a study carried out with professional female ballet dancers to better understand the potential factors leading to early hip osteoarthritis in this population. This research consisted in three study arms: a radiological examination, a clinical evaluation and a biomechanical analysis to provide a comprehensive assessment of the dancer’s hip. We concluded that the practice of dancing movements could cause a loss of hip joint congruence and recurrent superior/posterosuperior femoroacetabular impingements, which could lead to early degenerative lesions in the morphologically normal hip

An integrated platform for hip joint osteoarthritis analysis: design, implementation and results

Purpose: We present a software designed to improve hip joint osteoarthritis (OA) understanding using 3D anatomical models, magnetic resonance imaging (MRI) and motion capture. Methods: In addition to a standard static clinical evaluation (anamnesis, medical images examination), the software provides a dynamic assessment of the hip joint. The operator can compute automatically and in real-time the hip joint kinematics from optical motion capture data. From the estimated motion, the software allows for the calculation of the active range of motion, the congruency and the center of rotation of the hip joint and the detection and localization of the femoroacetabular impingement region. All these measurements cannot be performed clinically. Moreover, to improve the subjective reading of medical images, the software provides a set of 3D measurement tools based on MRI and 3D anatomical models to assist and improve the analysis of hip morphological abnormalities. Finally, the software is driven by a medical ontology to support data storage, processing and analysis. Results: We performed an in vivo assessment of the software in a clinical study conducted with 30 professional ballet dancers, a population who are at high risk of developing OA. We studied the causes of OA in this selected population. Our results show that extreme motion exposes the morphologically "normal” dancer's hip to recurrent superior or posterosuperior FAI and to joint subluxation. Conclusion: Our new hip software includes all the required materials and knowledge (images data, 3D models, motion, morphological measurements, etc.) to improve orthopedists' performances in hip joint OA analysi

Extreme leg motion analysis of professional ballet dancers via MRI segmentation of multiple leg postures

Purpose: Professional ballet dancers are subject to constant extreme motion which is known to be at the origin of many articular disorders. To analyze their extreme motion, we exploit a unique magnetic resonance imaging (MRI) protocol, denoted as ‘dual-posture' MRI, which scans the subject in both the normal (supine) and extreme (split) postures. However, due to inhomogeneous tissue intensities and image artifacts in these scans, coupled with unique acquisition protocol (split posture), segmentation of these scans is difficult. We present a novel algorithm that exploits the correlation between scans (bone shape invariance, appearance similarity) in automatically segmenting the dancer MRI images. Methods: While validated segmentation algorithms are available for standard supine MRI, these algorithms cannot be applied to the split scan which exhibits a unique posture and strong inter-subject variations. In this study, the supine MRI is segmented with a deformable models method. The appearance and shape of the segmented supine models are then re-used to segment the split MRI of the same subject. Models are first registered to the split image using a novel constrained global optimization, before being refined with the deformable models technique. Results: Experiments with 10 dual-posture MRI datasets in the segmentation of left and right femur bones reported accurate and robust results (mean distance error: 1.39 ± 0.31mm). Conclusions: The use of segmented models from the supine posture to assist the split posture segmentation was found to be equally accurate and consistent to supine results. Our results suggest that dual-posture MRI can be efficiently and robustly segmente

On the biomechanics of ligaments and muscles throughout the range of hip motion

At the limits of the range of hip motion, impingement, subluxation and edge loading can cause osteoarthritis in natural hips or early failure hip replacements. The aim of this PhD was to investigate the role of hip joint soft tissues throughout the range of hip motion to better understand their role in preventing (or perhaps even causing) these problematic load cases. A musculoskeletal model was used to investigate the muscular contribution to edge loading and found that in the mid-range of hip motion, the lines of action of hip muscles pointed inward from the acetabular rim and thus would stabilise the hip. However, in deep hip flexion with adduction, nearly half the muscles had unfavourable lines of action which could encourage edge loading. Conversely, in-vitro tests on nine cadaveric hips found that the hip capsular ligaments were slack in the mid-range of hip motion but tightened to restrain excessive hip rotation in positions close to the limits of hip motion. This passive restraint prevented the hip from moving into positions where the muscle lines of action were found to be unfavourable and thus could help protect the hip from edge loading. The ligaments were also found to protect the hip against impingement and dislocation. Out of the labrum, the ligamentum teres and the three capsular ligaments, it was found that the iliofemoral and ischiofemoral ligaments were primary restraints to hip rotation. These two capsular ligaments should be prioritised for protection/repair during hip surgery to maintain normal hip passive restraint. Whilst this can be technically demanding, failing to preserve/restore their function may increase the risk of osteoarthritic degeneration or hip replacement failure.Open Acces

Motion study of the hip joint in extreme postures

Many causes can be at the origin of hip osteoarthritis (e.g., cam/pincer impingements), but the exact pathogenesis for idiopathic osteoarthritis has not yet been clearly delineated. The aim of the present work is to analyze the consequences of repetitive extreme hip motion on the labrum cartilage. Our hypothesis is that extreme movements can induce excessive labral deformations and lead to early arthritis. To verify this hypothesis, an optical motion capture system is used to estimate the kinematics of patient-specific hip joint, while soft tissue artifacts are reduced with an effective correction method. Subsequently, a physical simulation system is used during motion to compute accurate labral deformations and to assess the global pressure of the labrum, as well as any local pressure excess that may be physiologically damageable. Results show that peak contact pressures occur at extreme hip flexion/abduction and that the pressure distribution corresponds with radiologically observed damage zones in the labrum