Abstract
[Purpose] We aimed to investigate the relationship between thoracic alignment asymmetry and side-to-side differences in femoral head deviation. [Participants and Methods] Twenty-six healthy adults participated in this study. We used three-dimensional motion analysis and ultrasonography to measure changes in femoral head deviation during isometric hip rotation and examine the relationship between thoracic alignment asymmetry and side-to-side differences. [Results] We observed that the femoral head deviated anteriorly during external rotation and posteriorly during internal rotation. At rest, the femoral head showed greater anterior deviation on the left side compared to the right. Task-induced femoral head deviation changes were greater on the right during external rotation and greater on the left during internal rotation. Moreover, we observed a positive correlation between the lower thoracic shape asymmetry and resting femoral head deviation. [Conclusion] Our findings suggest that lower thoracic asymmetry is associated with side-to-side differences in resting femoral head deviation and is potentially mediated through kinematic chain interactions.
Key words: Thoracic asymmetry, Femoral head deviation, Hip rotation
INTRODUCTION
Hip concentricity is crucial for preventing and managing hip diseases. A reduction in hip concentricity, coupled with the simultaneous onset of instability, increases the risk of hip disease1). A kinematic indicator of such instability is the anteroposterior displacement of the femoral head (femoral head deviation: FHD)2). An increase in FHD is associated with changes in joint range of motion3). However, in hip instability models created by separating the joint capsule and ligaments4), the hip joint axis of motion shifts anteriorly during hip flexion and internal rotation4), which causes functional impairments, including groin pain5). This instability is caused not only by ligaments but also by the collapse of static support mechanisms, including the labrum4, 6) and bone morphology7).
Furthermore, because the deep hip muscles connect to the joint capsule ligaments8, 9), a decrease in deep muscle function increases the FHD, contributing to the collapse of dynamic support mechanisms. Poor posture also contributes to various issues, such as bilateral coverage rate reduction due to increased lumbar lordosis, causing pelvic posterior tilt10) and unilateral coverage rate reduction11) due to increased spinal lateral flexion and rotation angles. Poor spinal alignment is always accompanied by worsened thoracic alignment.
Clinically, restoring normal thoracic kinetic chain function through thoracic alignment adjustments neutralizes spinal alignment, thereby facilitating greater stability in the lumbar-pelvic region. Recent studies focused on thoracic alignment asymmetry and its relationship with physical function. Honma and Sano reported that the greater the extent to which thoracic lateral deviation (TLD) causes the ribs and spine to deviate, the greater the asymmetry in the cross-sectional area of the quadratus lumborum and psoas major muscles12, 13) in the lumbar-pelvic region and around the hip joint, based on the correlation between TLD and this asymmetry. Given these findings, it is possible that even in healthy individuals, TLD or thoracic alignment asymmetry may cause lateral differences in FHD through spinal and pelvic alignment, affecting balance and hip conditions. As previously mentioned, the dynamic support mechanisms contributing to FHD are the deep hip muscles, many of which primarily act on hip rotation. Therefore, clarifying the relationship between FHD and thoracic alignment asymmetry associated with hip rotation is considered beneficial.
To apply these investigations clinically, data from participants with specific conditions are required. However, in patients with disease conditions, various factors, such as pain and deformity14), may influence the data. Therefore, this study focused on healthy individuals without pain, deformities, or relevant medical histories.
This study examined healthy participants performing seated isometric contractions (tasks) of hip internal rotation (IR) and external rotation (ER). We investigated whether these tasks induced changes in FHD and whether characteristic side-to-side differences were observed in resting or task-induced FHD. Furthermore, we aimed to determine whether these side-to-side differences correlate with TLD and thoracic alignment asymmetry, in order to clarify hip joint alignment from the viewpoint of thoracic alignment asymmetry.
PARTICIPANTS AND METHODS
The participants were 26 healthy adult males (age, 26.9 ± 3.4 years; height, 171 ± 0.0 cm; weight, 62.6 ± 8.5 kg; body mass index (BMI), 21.2 ± 2.7 kg/m2 [mean ± standard deviation]). The purpose of this study was fully explained to each participant at the time of measurement, and written consent was obtained before proceeding. This study was approved by the Tokyo Medical University Ethics Review Committee (Approval Number: T2020-0085). Individuals with pain or a history of pain in the thorax, spine, or hip joints, and those with a Beighton score of 5 or higher15) (an indicator of excessive joint mobility) were excluded, as these factors could potentially influence the measurement values.
We measured the resting TLD, asymmetric ratios of the upper and lower thoracic shapes (UTS and LTS), side-to-side differences in FHD, and changes during the task. A three-dimensional motion analysis system (Vicon NEXUS2, Vicon Motion Systems Ltd., Oxford, UK, 100 Hz) comprising eight infrared cameras, an ultrasound diagnostic device (HI VISION Preirus, Hitachi Medical Corporation), and a handheld dynamometer (HHD; micro FET2, Biometrics Europe BV, Almere, The Netherlands) were used.
The measurement position was set at 70° hip flexion, considering the influence of tension in the hip joint surrounding the ligaments16) and the fact that the function of the rotational muscles involved in the task changes up to 60° of hip flexion17). Furthermore, the starting (rest) position was seated, with the distal third of the thigh positioned at the front edge of the seat surface and the lower limbs in a drooped position (Fig. 1).
Fig. 1.
Resting position. a: frontal plan, b: sagittal plan.
Hip flexion was set at 70°. Furthermore, the distal one-third of the thigh was positioned at the anterior end of the seat, with the lower limbs hanging freely in a relaxed sitting posture (rest).
Measurement of the TLD and thoracic alignment asymmetry followed previous studies using 20 infrared markers with a diameter of 9.5 mm12, 13, 18) (Figs. 2 and 3). TLD was defined by calculating the thoracic center point relative to the pelvic center point in the frontal plane. The thoracic center point was defined as the midpoint of the line segment connecting the xiphoid process (XP) and the spinous process of the tenth thoracic vertebra. The pelvic center point was determined by first calculating the midpoints of the line segments connecting the bilateral anterior superior iliac spines and the bilateral posterior superior iliac spines. The midpoint of the line segment connecting these two midpoints was then defined as the pelvic center. TLD (mm) was calculated as=Thoracic Center (x-axis coordinate) − Pelvic Center (x-axis coordinate)12, 13, 18). Negative values indicated left thoracic deviation (LTD) relative to the pelvis (LTD group), while positive values indicated right thoracic deviation (RTD) relative to the pelvis (RTD group).
Fig. 2.
Marker placements for thoracic lateral deviation (TLD).
TLD (mm)=thoracic center (X-axis coordinates) − pelvic center (X-axis coordinates), where negative values were defined as left lateral deviation of the thorax relative to the pelvis (left thoracic deviation group: LTD) and positive values as right lateral deviation of the thorax relative to the pelvis (right thoracic deviation group: RTD). RPSIS: right posterior superior iliac spine; RASIS: right anterior superior iliac spine; LPSIS: left posterior superior iliac spine; LASIS: left anterior superior iliac spine.
Fig. 3.
Marker placements for thoracic shape.
a: Upper thoracic shape (UTS), b: Lower thoracic shape (LTS). Calculated as right anteroposterior diameter/left anteroposterior diameter=asymmetric ratio of the UTS and LTS.
For the UTS asymmetry ratio, the thoracic spinous process (B) at the same level as the mid-sternum at the second thoracocostal joint was used as a reference. Three points each on the left and right sides (A1–A6) were placed at the same level as B. For the LTS asymmetry ratio, the XP (C) was used as the reference, and three points each on the left and right sides (D1–D6) were placed at the same level as C. The UTS and LTS were calculated as the sum of the distances from the reference point to the three points on each side at the same level. This sum was defined as the anteroposterior diameter of the thoracic diameters on the right and left sides, and the asymmetric UTS and LTS ratios were calculated as the right anteroposterior diameter/left anteroposterior diameter18). The distance between the markers was set to 13% of the distance between both acromions, and the markers were placed at equal horizontal intervals using a line laser and tape measure. Measurements were taken with the participants looking straight ahead in a resting position. To avoid thoracic shape changes due to breathing, measurements were performed in the end-expiratory position for 5 s and repeated three times. Data from the central 3 s of each of the three trials were selected, and the average of these three trials was considered as the representative value. Data were analyzed using Body Builder analysis software (Vicon Motion Systems).
The task movement comprised isometric contraction of the IR and ER muscles using an HHD. The load was set at 2% of the body weight, which was determined in advance to avoid femoral adduction/abduction of more than 5°.
The FHD during rest and during the task was measured using an ultrasound diagnostic device. The imaging mode was B-mode using a linear probe (5–10 MHz). Following previous studies, the probe was positioned to visualize the acetabulum and junction between the femoral head and neck, adjusting the view such that the femoral head appeared as a superficial layer relative to the acetabulum (Fig. 4)19). Three measurements were taken on each side, and the average of the three was used as the representative value. The images were analyzed using ImageJ 1.52v (National Institutes of Health, Bethesda, MA, USA) to calculate the distance between the most superficial part of the femoral head and the acetabulum, normalized for each participant’s height. Negative values were assigned to anterior displacement of the femoral head relative to the acetabulum, and positive values to posterior displacement. The FHD change during the task was calculated for both ER and IR by combining left and right sides, as follows: FHD change=task − resting, and the FHD difference between the sides was calculated as FHD difference=right − left.
Fig. 4.
Ultrasound images of femoral had deviation.
The prove was positioned such that the acetabular, diaphyseal, and cervical junctions were visible, and adjusted so that the femoral head was superficial to the acetabulum. The distance between the most superficial part of the femoral head and the acetabulum was calculated.
Statistical analyses were performed using IBM SPSS Statistics for Windows version 26 (IBM, Armonk, NY, USA). For all participants, as well as those in the LTD group, the mean values and 95% confidence intervals (95% CIs) were calculated for resting TLD, thoracic alignment asymmetry, and bilateral task-related FHD changes during ER and IR. After assessing the normality of each dataset using the Shapiro–Wilk test, comparisons between the left and right sides were performed for resting FHD and FHD changes (paired t-test or Wilcoxon signed-rank test). Furthermore, a correlation analysis was performed to examine the relationship between asymmetry in TLD and thoracic alignment and the side-to-side difference in resting FHD and FHD change in all participants (using Spearman’s rank correlation coefficient or Pearson’s correlation coefficient). The level of statistical significance was set at p<0.05.
RESULTS
The mean values and 95% CI for TLD and thoracic alignment asymmetry are presented in Table 1. Among the 26 participants, 24 had LTD and two had RTD, with a large proportion having a thoracic shift to the left.
Table 1. Mean and 95% CI of thoracic alignment asymmetry.
| All participants (n=26) | LTD (n=24) | RTD (n=2) | |
| TLD (mm) | −7.7 ± 6.8 (−10.4 to −4.9) | −8.9 ± 5.4 (−11.2 to −6.7) | 7.6 ± 6.3 |
| Asymmetric ratio of UTS (Rt/Lt) | 0.98 ± 0.02 (0.97 to 0.99) | 0.98 ± 0.01 (0.97 to 0.99) | 0.97 ± 0.00 |
| Asymmetric ratio of LTS (Rt/Lt) | 1.02 ± 0.01 (1.02 to 1.03) | 1.02 ± 0.01 (1.02 to 1.03) | 1.00 ± 0.01 |
Values are mean ± SD (95% CI).
LTS: lower thoracic shape; TLD: thoracic lateral deviation; UTS: upper thoracic shape; LTD: left thoracic deviation; RTD: right thoracic deviation.
The mean values and 95% CI for the FHD changes during the task are presented in Table 2. ER caused an anterior shift, while IR caused a posterior shift.
Table 2. Mean and 95% CI of femoral head deviation (FHD) change.
| FHD (mm/height) | All participants (n=52) | LTD (n=48) | RTD (n=4) |
| ER change | 0.6 ± 0.4 (0.5 to 0.7) | 0.6 ± 0.4 (0.4 to 0.7) | 0.8 ± 0.3 |
| IR change | −0.6 ± 0.5 (−0.7 to −0.4) | −0.6 ± 0.5 (−0.7 to −0.4) | −0.4 ± 0.4 |
Values are mean ± SD (95% CI).
LTD: left thoracic deviation; RTD: right thoracic deviation; ER: external rotation; IR: internal rotation.
The resting FHD values and side-to-side differences in FHD changes are presented in Table 3. In all participants and those with LTD, resting FHD was significantly more anterior on the left side than on the right (p<0.01, p<0.01). Furthermore, during ER, FHD shifted significantly anteriorly on the right side (p<0.01, p<0.05), whereas during IR, it shifted significantly posteriorly on the left side (p<0.01, p<0.01).
Table 3. Mean and standard deviation (SD) of femoral head deviation (FHD).
| FHD (mm/height) | All participants (n=26) | LTD (n=24) | RTD (n=2) | |
| Rest | Rt | −3.0 ± 1.2** | −3.0 ± 1.2** | −3.1 ± 0.7 |
| Lt | −2.5 ± 0.9 | −2.5 ± 0.9 | −2.9 ± 1.2 | |
| ER change | Rt | 0.7 ± 0.4** | 0.7 ± 0.4* | 0.9 ± 0.3 |
| Lt | 0.5 ± 0.4 | 0.5 ± 0.4 | 0.6 ± 0.0 | |
| IR change | Rt | −0.4 ± 0.4** | −0.4 ± 0.4** | −0.1 ± 0.2 |
| Lt | −0.8 ± 0.5 | −0.8 ± 0.5 | −0.6 ± 0.3 | |
Values are mean ± SD.
*Significantly different (p<0.05) from left, **Significantly different (p<0.01) from left.
LTD: left thoracic deviation; RTD: right thoracic deviation; ER: external rotation; IR: internal rotation.
Table 4 presents the correlation coefficients between the TLD and thoracic alignment asymmetry and the side-to-side differences in FHD in all participants. A significant positive correlation was observed between the asymmetric ratio of the LTS and the side-to-side differences in resting FHD (p<0.01).
Table 4. Correlation coefficients between thoracic asymmetry and femoral head deviation (FHD) difference.
| Difference in FHD at rest (Rt-Lt) | Difference in FHD at ER (Rt-Lt) | Difference in FHD at IR (Rt-Lt) | |
| TLD (mm) | −0.25 | 0.10 | −0.25 |
| Asymmetric ratio of UTS (Rt/Lt) | −0.24 | 0.24 | −0.10 |
| Asymmetric ratio of LTS (Rt/Lt) | 0.62** | 0.11 | −0.21 |
n=26, **Significantly different (p<0.01).
LTS: lower thoracic shape; TLD: thoracic lateral deviation; UTS: upper thoracic shape; ER: external rotation; IR: internal rotation.
DISCUSSION
This study investigated the relationship between asymmetry in thoracic alignment and side-to-side differences in FHD in healthy individuals. Most participants in this study had a thorax that deviated to the left relative to the pelvis. Furthermore, the asymmetric ratio of the UTS was less than 1, indicating a greater diameter on the left side than on the right, whereas the asymmetric ratio of the LTS was greater than 1, indicating a greater diameter on the right side than on the left18). These results, as in previous studies, indicate that thoracic alignment is asymmetrical even in healthy individuals12, 13, 18). Studies examining thoracic alignment have reported correlations with asymmetry in the cross-sectional areas of the quadratus lumborum and psoas major muscles12, 13). Therefore, the thoracic alignment asymmetry may also cause lateral differences in the lumbar spine, pelvis, and hip joints. The results of this study showed side-to-side differences in FHD, which correlated with thoracic alignment asymmetry.
The FHD shifted anteriorly during ER and posteriorly during IR on both sides. As the task in this study involved isometric contraction, movement occurred in the acetabulum relative to the femur. Therefore, during ER, the activity of the external rotators (the quadratus femoris, obturator internus and externus, and lower fibers of the gluteus maximus) causes the acetabulum to move medially. This results in the acetabulum moving posteriorly, reducing the coverage ratio, and causing the femoral head to shift anteriorly relative to the acetabulum. In addition, during IR, the opposite occurs because of the activity of the internal rotators (gluteus minimus, gluteus medius, upper fibers of the gluteus maximus, etc.), resulting in a relative posterior shift of the femoral head. As the measurement position was seated and the pelvis was fixed, the observed changes were likely caused by mobility of the acetabulum, such as at the sacroiliac joint and pubic symphysis, due to the activity of the deep muscles. Previous studies have demonstrated that sagittal plane pelvic alignment influences hip joint range of motion20). Although this study focused on isometric contraction and horizontal plane dynamics, it is likely that changes in pelvic alignment also influenced the observed FHD.
At rest, FHD was significantly more anterior on the left side compared to the right. The side-to-side difference in FHD change showed a significant anterior deviation on the right during ER and a significant posterior deviation on the left during IR. Considering these side-to-side differences alongside the changes in FHD during the task, it is suggested that the anterior deviation on the left side activated the external rotator muscles associated medially with the acetabulum, while the posterior deviation on the right side activated the internal rotator muscles associated laterally with the acetabulum. This may have caused a head deviation similar to that seen in the shoulder joint21), resulting in a side-to-side difference in the resting FHD. Furthermore, the side-to-side differences observed in the FHD change are thought to be influenced by the side-to-side differences in resting FHD. On the right side, where the resting position deviated posteriorly, the amount of change increased during ER, as the range of motion shifted anteriorly. On the left side, where the situation was reversed, the amount of change increased during IR, as the range of motion shifted posteriorly. In other words, the amount of FHD change is expected to be influenced by the side-to-side difference in resting FHD. Studies using computed tomography to investigate the morphological symmetry of the hip joint have shown a significantly lower anterior coverage rate on the left side22). Therefore, results similar to those in this study may be observed for LTD in healthy individuals.
A positive correlation was observed between the LTS asymmetric ratio and the resting FHD side-to-side difference. Asymmetric acetabular alignment, such as right acetabular medial alignment or left acetabular lateral alignment, as suggested by FHD dynamics, may occur at the sacroiliac joint and pubic symphysis23, 24). Consequently, the correlation observed between the hip joint and LTS is thought to have been caused by slight multi-segmental kinetic chains, including the costovertebral joints, thoracolumbar spine, sacrum, and acetabulum. In other words, the LTS asymmetric ratio suggests that it can correct the side-to-side differences in FHD.
A limitation of this study is that morphological characteristics were not examined. Previous studies have reported associations between morphological features and FHD during joint movement3), and others have investigated side-to-side asymmetry in morphological characteristics, such as the femoral and acetabular anteversion angles22, 25). Although organic factors were excluded from this study, FHD could only be examined in relation to some factors, making a comprehensive analysis difficult. Furthermore, a correlation was observed only for the asymmetric ratio of LTS, and no correlation was found with other factors; the details remain unclear. Therefore, we believe that examining the segmental motion between the thoracic shape and the hip joint will clarify the detailed mechanisms underlying the present findings.
In conclusion, LTD was associated with left-sided anterior and right-sided posterior FHD. The side-to-side characteristics of the rotator muscles were suggested by changes in FHD during the task. Furthermore, a relationship was observed between these side-to-side differences and the asymmetric LTS ratio. These findings are novel and indicate that thoracic alignment asymmetry influences both static and dynamic hip alignment. However, approaches to improve thoracic alignment asymmetry have not been academically established, highlighting the need for future intervention studies. These findings suggest that improving thoracic alignment asymmetry can influence hip alignment, thereby contributing to injury prevention and intervention in hip diseases.
Conflict of interest
The authors declare that there is no conflict of interests regarding the publication of this article.
REFERENCES
- 1.Irie T, Takahashi D, Asano T, et al. : Is there an association between borderline-to-mild dysplasia and hip osteoarthritis? Analysis of CT osteoabsorptiometry. Clin Orthop Relat Res, 2018, 476: 1455–1465. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Scott CP, d’Hemecourt PA, Miller PE, et al. : Femoroacetabular translation in female athletes and dancers assessed by dynamic hip ultrasonography. BMJ Open Sport Exerc Med, 2021, 7: e001169. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Kiapour AM, Mitchell C, Hosseinzadeh S, et al. : Association between hip translation and hip rotation and anatomy: a pilot quasi-static MRI study. Orthop J Sports Med, 2024, 12: 23259671241275662. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Kalisvaart MM, Safran MR: Microinstability of the hip-it does exist: etiology, diagnosis and treatment. J Hip Preserv Surg, 2015, 2: 123–135. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Han S, Alexander JW, Thomas VS, et al. : Does capsular laxity lead to microinstability of the native hip? Am J Sports Med, 2018, 46: 1315–1323. [DOI] [PubMed] [Google Scholar]
- 6.Myers CA, Register BC, Lertwanich P, et al. : Role of the acetabular labrum and the iliofemoral ligament in hip stability: an in vitro biplane fluoroscopy study. Am J Sports Med, 2011, 39: 85S–91S. [DOI] [PubMed] [Google Scholar]
- 7.Fujiwara Y, Shoji T, Ota Y, et al. : Relationships among hip instability, iliofemoral ligament, and pain in patients with developmental dysplasia of the hip. J Orthop Sci, 2024, 29: 835–840. [DOI] [PubMed] [Google Scholar]
- 8.Tsutsumi M, Nimura A, Akita K: New insight into the iliofemoral ligament based on the anatomical study of the hip joint capsule. J Anat, 2020, 236: 946–953. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Tsutsumi M, Nimura A, Utsunomiya H, et al. : Anatomic study of hip pericapsular muscle arrangement on the joint capsule. JBJS Open Access, 2025, 10: 1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Uemura K, Atkins PR, Peters CL, et al. : The effect of pelvic tilt on three-dimensional coverage of the femoral head: a computational simulation study using patient-specific anatomy. Anat Rec (Hoboken), 2021, 304: 258–265. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Luo Q, Kim YC, Kim KT, et al. : Surgical correction for adult spinal deformity increases acetabular lateral coverage of femoral heads. BMC Musculoskelet Disord, 2021, 22: 988. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Homma Y, Hirayama T, Mohara A, et al. : Relations of bilateral symmetry in the cross-sectional area of the quadratus lumborum muscles to posture in the frontal plane and respiratory function in forced breathing. Rigakuryoho Kagaku, 2018, 33: 501–506 (in Japanese with English abstract). [Google Scholar]
- 13.Sano T, Komuro N, Homma Y, et al. : Relationship between lateral thoracic deviation and left-right ratio of psoas major cross-sectional area. Rigakuryoho Kagaku, 2022, 37: 297–301 (in Japanese with English abstract). [Google Scholar]
- 14.Tajiri M, Hieda H: A quantitative analysis of the muscle atrophy in osteoarthritis of the hip by computed tomography. Orthop Traumatol, 1984, 32: 823–827. [Google Scholar]
- 15.Yokoe T, Tajima T, Yamaguchi N, et al. : Association between the Beighton score and stress ultrasonographic findings of the anterior talofibular ligament in healthy young women: a cross-sectional study. J Clin Med, 2022, 11: 1759. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Yen CH, Leung HB, Tse PY: Effects of hip joint position and intra-capsular volume on hip joint intra-capsular pressure: a human cadaveric model. J Orthop Surg Res, 2009, 4: 8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Delp SL, Hess WE, Hungerford DS, et al. : Variation of rotation moment arms with hip flexion. J Biomech, 1999, 32: 493–501. [DOI] [PubMed] [Google Scholar]
- 18.Komuro N, Kakizaki F, Hirosawa A, et al. : Relationship between the thoracic asymmetry in standing position and the asymmetry of ankle moment in the frontal plane during gait. J Phys Ther Sci, 2023, 35: 18–23. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.d’Hemecourt PA, Sugimoto D, McKee-Proctor M, et al. : Can dynamic ultrasonography of the hip reliably assess anterior femoral head translation? Clin Orthop Relat Res, 2019, 477: 1086–1098. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Cibulka MT, Sinacore DR, Cromer GS, et al. : Unilateral hip rotation range of motion asymmetry in patients with sacroiliac joint regional pain. Spine, 1998, 23: 1009–1015. [DOI] [PubMed] [Google Scholar]
- 21.Werner CM, Nyffeler RW, Jacob HA, et al. : The effect of capsular tightening on humeral head translations. J Orthop Res, 2004, 22: 194–201. [DOI] [PubMed] [Google Scholar]
- 22.Mascarenhas VV, Rego P, Dantas P, et al. : Hip shape is symmetric, non-dependent on limb dominance and gender-specific: implications for femoroacetabular impingement. A 3D CT analysis in asymptomatic subjects. Eur Radiol, 2018, 28: 1609–1624. [DOI] [PubMed] [Google Scholar]
- 23.Pool-Goudzwaard A, Gnat R, Spoor K: Deformation of the innominate bone and mobility of the pubic symphysis during asymmetric moment application to the pelvis. Man Ther, 2012, 17: 66–70. [DOI] [PubMed] [Google Scholar]
- 24.Shi NN, Shen GQ, He SY, et al. : [X-ray characteristics of sacroiliac joint disorders and its clinical significance]. Zhongguo Gu Shang, 2013, 26: 102–106 (in Chinese). [PubMed] [Google Scholar]
- 25.Dimitriou D, Tsai TY, Yue B, et al. : Side-to-side variation in normal femoral morphology: 3D CT analysis of 122 femurs. Orthop Traumatol Surg Res, 2016, 102: 91–97. [DOI] [PubMed] [Google Scholar]