Effect of hip angle on anterior hip joint force during gait
Introduction
Hip or groin pain is a common complaint for which people are referred for physical therapy, with the hip region being involved in approximately 2% to 11% of running injuries [1]. The Physical Stress Theory, as presented by Mueller and Maluf [2], proposes that excessive stress, that is stress that exceeds a tissue's tolerance, results in tissue injury and pain. In the case of anterior hip pain, we propose that the excessive stress can be due to repetitive forces into the connective tissues of the anterior hip joint (e.g. acetabular labrum). Running may be one example of an activity where low magnitude forces are repeatedly applied, and may contribute to the development of a labral tear [3], [4] and anterior hip pain [5]. The exact mechanism by which running may lead to a tear in the acetabular labrum has not been specified; however, the pattern of repeated hip hyperextension has been implicated [4], [5]. Sahrmann proposes that long distance running is often associated with increased anterior glide of the femoral head relative to the acetabulum as a result of hip hyperextension [5]. The increased femoral anterior glide could lead to increased force on the anterior hip joint structures and tearing of the anterior acetabular labrum. This mechanism could explain the labral tears which Guanche and Sikka [4] found in eight high-level runners with hip pain. None of the runners reported any associated trauma with the development of the hip pain yet all eight had a tear of the anterosuperior region of the acetabular labrum. Guanche and Sikka [4] theorized that the hip hyperextension inherent in the stance phase of running leads to “subtle instability and increasing stress at the cartilage–labral junction” (p. 584).
Clinically, we have noted that patients with anterior hip pain often walk with greater maximum hip extension than people without hip pain. The patients typically report pain at the end of the stance phase of gait when the hip is in hyperextension. Furthermore, we have noted that patients with anterior hip pain report an immediate reduction in their hip pain when instructed to walk with less hip extension. We theorize that this reduction in hip pain is due to a decrease in the anterior hip joint force subsequent to the decreased hip extension.
Prior musculoskeletal simulations of hip exercises have demonstrated a relationship between hip joint forces and hip angle [6], [7]. In these studies, hip joint force was estimated when performing hip flexion in supine and hip extension in prone. Anterior hip joint force was found to increase with increasing hip extension angle independent of the muscles activated. The models used in these studies, however, were quasi-static evaluations of simulated single plane movements. Only the torque due to gravity was included. It is unclear if a similar relationship between force and hip angle exists during more complex activities such as gait.
The purpose of this paper, therefore, was to investigate forces on the anterior hip joint tissues during gait which may contribute to hip pain on a daily basis. We used a musculoskeletal model to estimate hip joint forces during normal gait to investigate the effect of end range hip extension on the anterior hip joint force. We hypothesized that the anterior hip joint force would be higher in walking trials with greater hip extension range of motion than in trials with less hip extension.
Section snippets
Methods
We used a 6 degree of freedom (DOF), three-dimensional musculoskeletal model of a leg to estimate joint forces in the hip, knee, and ankle. This model was a simplification of a bilateral model developed by Carhart [8] and has been used in other studies [6], [7]. The model consists of a pelvis, thigh, shank and foot of the right leg. The six DOF represent the primary motions at the hip, knee and ankle as follows: (i) 3 DOF at the hip to model abduction–adduction, internal–external rotation and
Results
The musculoskeletal model indicated that the hip force in the transverse plane due to muscle alone is primarily in the anterior direction during the stance phase of gait (Fig. 2). During the initial 8% of the gait cycle, the hip joint force is posterior. From approximately 9% to 67% of the gait cycle, the force is in the anterior direction. The anterior force peaks around 50% of the gait cycle, just prior to ipsilateral toe off. The maximum hip extension angle occurs at about 51% of the gait
Discussion
The results of the musculoskeletal model indicate that the anteriorly directed hip joint forces are higher when walking in greater hip extension than when walking in less hip extension. The model predicted a 24% increase in the normalized anterior hip joint force due to muscle with only a 2° increase in the maximum hip extension angle. The maximum anterior hip joint force occurs just before the hip reaches its maximum hip extension angle, further implicating an interaction between anterior hip
Conflict of interest
The authors affirm that they have no financial affiliation or involvement with any commercial organization that has direct financial interest in any matter included in this manuscript.
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2023, Journal of Orthopaedic TranslationEffect of simulated changes in pelvic tilt on hip joint forces
2022, Journal of BiomechanicsCitation Excerpt :Thus, changing pelvic tilt is a possible intervention to address pathological conditions and reduce hip pain. Pain may result from excessive anteriorly-directed joint forces onto the acetabulum (Lewis et al., 2010); increasing anterior tilt may reduce those forces. One can also increase posterior tilt to reduce medially-directed forces, although the therapeutic indications are unexplored.