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Optimal Trochanter Major Position During Functional Activities in Healthy Individuals
Torsional abnormalities of the proximal femur are highly prevalent in the presence of hip pain, with a reported prevalence of 17% in patients who are eligible for hip preservation surgery for femoroacetabular impingement (FAI) or developmental hip dysplasia (DHH). Abnormal femoral torsion (FT) is a well-established independent risk factor for the development of early hip osteoarthritis as increased FT could cause under-coverage of the femoral head, resulting in an overload of the anterosuperior joint and posterior, extra-articular, ischiofemoral impingement with levering out of the femoral head, whereas a decreased FT could lead to anterior femoroacetabular impingement (FAI). Untreated FT abnormalities could compromise the results of open and arthroscopic hip preservation surgeries for FAI. Although torsional abnormalities of the proximal femur can be addressed with a subtrochanteric rotational osteotomy, the optimal FT correction remains unknown.
Variations of the rotational morphology of the proximal femur might have a profound effect on hip biomechanics, as FT could influence the hip range of motion (especially internal and external rotation), the position of the greater trochanter (GT), periarticular muscle lever arms and gait pattern. FT angles and clinical evaluation of the patient (especially passive internal rotation of the hip) are the base of current recommendations for rotational osteotomies. However, in many cases, femoral and tibia torsion (TT) values measured on computer tomography (CT), the gold standard method for measuring FT and TT, are not consistent with the rotational profile during gait as observed during the clinical examination or gait analysis, suggesting a dynamic compensation.
Up-to-date, limited data are available regarding the dynamic compensation of the hip in healthy individuals during functional activities. The present study hypothesis is that the position of the GT during maximal hip abductor muscle activation, defined as peak joint reaction force (JRFs), would be similar in all patients, regardless of FT, resulting however in different internal rotation of the femur relative to the pelvis to achieve this biomechanical optimal position.
Fifteen individuals scheduled to undergo a subtrochanteric femoral osteotomy at our institution due to symptomatic torsional abnormality of the proximal femur (high or low FT) and fifteen match-controlled individuals (age, gender, BMI), without hip complaints and history of previous hip surgery or trauma will be recruited.
All the subjects will undergo an ultra-low-dose computed tomography (CT) of the lower extremity with 48 markers attached, for the following 3D gait analysis. Then 3D models of the entire lower extremities with the markers in place will be reconstructed for measuring several anatomical parameters including FT and TT. The center of the GT will also be identified in CT position and the 3D position compared to the skin markers will be noted. A gait lab analysis will be performed to determine kinematic data of the pelvic, hip, knee and foot during functional activities (level walking, stairs, standing from a sitting position, one-leg stand, squats and lunges ). These functional activities will be recorded using an optical motion capture system (Vicon Motion Systems Ltd., Oxford, UK) including 24 cameras (type MX T10 and type MX T20-S). GRFs will be measured using two portable Kistler force plates (9260AA) (Kistler Group, Winterthur, Switzerland). Cameras and force plates will be time-synchronized (Vicon Nexus) and the so obtained information allows computing of subject-specific JRFs in the lower extremities through musculoskeletal simulations.
Tasks:
- Define the anatomical coordinate system of the hip
- Measure the maximal internal rotation of each individual hip based on a 3D model
- Use the data from the gait analysis and the markers on CT to identify the transverse kinematics of the hip (i.e. internal and external rotation) and describe the position of the greater trochanter during the gait cycle
- Describe the trochanter position at the point of the gait cycle which demonstrates the greatest JRF
Requirements:
- Good MATLAB skills are an asset
- Ability to work independently
Up-to-date, limited data are available regarding the dynamic compensation of the hip in healthy individuals during functional activities. The present study hypothesis is that the position of the GT during maximal hip abductor muscle activation, defined as peak joint reaction force (JRFs), would be similar in all patients, regardless of FT, resulting however in different internal rotation of the femur relative to the pelvis to achieve this biomechanical optimal position. Fifteen individuals scheduled to undergo a subtrochanteric femoral osteotomy at our institution due to symptomatic torsional abnormality of the proximal femur (high or low FT) and fifteen match-controlled individuals (age, gender, BMI), without hip complaints and history of previous hip surgery or trauma will be recruited. All the subjects will undergo an ultra-low-dose computed tomography (CT) of the lower extremity with 48 markers attached, for the following 3D gait analysis. Then 3D models of the entire lower extremities with the markers in place will be reconstructed for measuring several anatomical parameters including FT and TT. The center of the GT will also be identified in CT position and the 3D position compared to the skin markers will be noted. A gait lab analysis will be performed to determine kinematic data of the pelvic, hip, knee and foot during functional activities (level walking, stairs, standing from a sitting position, one-leg stand, squats and lunges ). These functional activities will be recorded using an optical motion capture system (Vicon Motion Systems Ltd., Oxford, UK) including 24 cameras (type MX T10 and type MX T20-S). GRFs will be measured using two portable Kistler force plates (9260AA) (Kistler Group, Winterthur, Switzerland). Cameras and force plates will be time-synchronized (Vicon Nexus) and the so obtained information allows computing of subject-specific JRFs in the lower extremities through musculoskeletal simulations.
Tasks: - Define the anatomical coordinate system of the hip - Measure the maximal internal rotation of each individual hip based on a 3D model - Use the data from the gait analysis and the markers on CT to identify the transverse kinematics of the hip (i.e. internal and external rotation) and describe the position of the greater trochanter during the gait cycle - Describe the trochanter position at the point of the gait cycle which demonstrates the greatest JRF
Requirements: - Good MATLAB skills are an asset - Ability to work independently
To report the transverse plane kinematics of the hip and dynamic alterations of the GT position during functional activities in healthy individuals using a three-dimensional (3D) gait analysis.
To report the transverse plane kinematics of the hip and dynamic alterations of the GT position during functional activities in healthy individuals using a three-dimensional (3D) gait analysis.