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Objectives. Based on deep learning semantic segmentation model, we sought to assess pelvic tilt by area ratio of the lesser pelvic and the obturator foramen in anteroposterior (AP) radiographs. Background. Pelvic tilt is a critical factor in hip and spinal surgery, commonly evaluated by medical professionals through sagittal pelvic radiographs. The inherent pelvic asymmetry, as well as potential obstructions from clothing and musculature in roentgenography, may result in ghosting and blurring artifacts, thereby complicating precise measurement. Methods. PT directly affects the area ratio of the lesser pelvis to the obturator foramen in AP radiographs. An exponential regression analysis of simulated radiographs from ten male and ten female pelvises in specific tilt positions derived a formula correlating this area ratio with PT. Two blinded investigators evaluated this formula using 161 simulated AP pelvic radiographs. A deep learning semantic segmentation model was then fine-tuned to automatically calculate the area ratio, enabling intelligent PT evaluation. This model and the regression function were integrated for automated PT measurement and tested on a dataset of 231 clinical cases. Results. We observed no disparity between men and women in the aforementioned area ratio. The test results from two blinded investigators analyzing 161 simulated radiographs revealed a mean absolute error of 0.19° (SD ± 4.71°), with a correlation coefficient between them reaching 0.96. In addition, the mean absolute error obtained from testing 231 clinical AP radiographs using the fine-tuned semantic segmentation model mentioned earlier is 0.58° (SD ± 5.97°). Conclusions. We found that using deep learning neural networks enabled a more accurate and robust automatic measurement of PT through the area ratio of the lesser pelvis and obturator foramen. [ABSTRACT FROM AUTHOR]

Study Design. Retrospective cohort. Objective. Examine the relationship between compensatory pelvic retroversion, positive sagittal imbalance (measured by C2 tilt), and the C2 pelvic angle (C2PA) in patients before long spinal fusions; and to determine the association between changes in C2PA and pelvic tilt (PT) following long spinal fusions. Background. Adult spinal deformity surgical goals often include a PT target, yet patients frequently demonstrate persistent compensatory pelvic retroversion following surgery. Methods. Adults above 18 years old undergoing long spinal fusions (> 4 levels) with standing preoperative and postoperative radiographs were included. To examine drivers of preoperative sagittal balance, regression models were fit to estimate the association between preoperative C2PA and pelvic incidence with preoperative PT and C2 tilt. To predict postoperative change in PT, multivariable regression was used to estimate change in PT, adjusting for change in C2PA and preoperative C2 tilt. Results. Among the 80 patients identified, the median age was 61 (IQR: 45-72) and 46 (58%) were female. The median number of levels fused was 10 (IQR: 8-13) and 55 (69%) were instrumented to the sacrum/pelvis. Preoperative C2PA had a significant nonlinear association with preoperative PT (r2=0.81, P<0.001) and preoperative C2 tilt (r2= 0.41, P= 0.002). Postoperative change in PT was strongly associated with change in C2PA (β=0.81; P<0.001) and preoperative C2 tilt (β= 0.55; P< 0.001). Conclusions. Following long spinal fusions, change in PT (or lack thereof) can be reliably predicted based on change in C2PA and preoperative C2 tilt. In patients with normal preoperative C2 tilt, the change in C2PA is nearly equivalent to the change in PT, but in patients with more positive C2 tilt (sagittal imbalance), a greater change in C2PA will be required to achieve an equivalent change in PT. [ABSTRACT FROM AUTHOR]

AbstractPurposeMethodsResultsConclusionsSystematic review and meta-analysis to examine common static postural parameters between participants with and without low back pain (LBP).Systematic search on the PubMed, CINAHL, Embase and SCOPUS databases using keywords ‘posture’ and ‘low back pain’. Observational studies comparing static postural outcomes (e.g. lumbar lordosis) between participants with and without LBP were included. Two independent reviewers conducted screening, data extraction and quality assessment. Methodological quality was assessed using Joanna Briggs Institute’s critical appraisal tools.Studies included in review = 46 (5,097 LBP; 6,974 controls); meta-analysis = 36 (3,617 LBP; 4,323 controls). Quality of included studies was mixed. Pelvic tilt was statistically significantly higher in participants with LBP compared to controls (n = 23; 2,540 LBP; 3,090 controls; SMD:0.23, 95%CI:0.10,0.35, p < 0.01, I2=72%). Lumbar lordosis and sacral slope may be lower in participants with LBP; pelvic incidence may be higher in this group; both were not statistically significant and the between study heterogeneity was high. Thoracic kyphosis and leg length discrepancy showed no difference between groups.Lumbopelvic mechanisms may be altered in people with LBP, but no firm conclusions could be made. Pelvic tilt appeared to be increased in participants with LBP. Postural variable measurement needs standardisation. Better reporting of study characteristics is warranted.Implications for rehabilitationLumbo pelvic parameters especially pelvic tilt may be altered in people with low back pain, although no firm conclusion could be made due to the high heterogeneity between studies.Postural assessment within low back pain rehabilitation may therefore require an individualistic approach.Lumbo pelvic parameters especially pelvic tilt may be altered in people with low back pain, although no firm conclusion could be made due to the high heterogeneity between studies.Postural assessment within low back pain rehabilitation may therefore require an individualistic approach. [ABSTRACT FROM AUTHOR]

We evaluated whether the clinical outcomes, including postoperative knee range of motion (ROM), after unicompartmental knee arthroplasty (UKA) were associated with the sagittal spinopelvic parameters and coronal alignment of the full lower extremity. Forty-two patients (50 knees: six men, seven knees; 36 women, 43 knees) who underwent medial UKA between April 2015 and December 2022 were included. Preoperative radiographic examinations of the index for sagittal spinopelvic alignment included the sagittal vertical axis (SVA), lumbar lordosis, sacral slope (SS), pelvic tilt (PT), and pelvic incidence. The anteroposterior hip-knee-ankle angle (HKAA) was calculated. The relationship of clinical outcomes and the risk of knee flexion angle ≤125° and knee flexion contracture ≥10° 1-year post-UKA with radiographic parameters were evaluated. Preoperative HKA angle affected postoperative knee flexion angle ≤125° (p = 0.017, 95% confidence interval [CI]: 0.473–0.930) in logistic regression analysis. Patients with a knee flexion angle ≤125° had a higher preoperative HKAA (9.8 ± 3.0°), higher SVA (83.8 ± 37.0 mm), and lower SS (23.7 ± 9.0°) than those with a flexion angle >125° (preoperative HKAA: 6.6 ± 4.0°, SVA: 40.3 ± 46.5 mm, SS: 32.0 ± 6.3°) (p = 0.029, 0.012, and 0.004, respectively). PT related to postoperative knee flexion contracture ≥10° (p = 0.010, 95% CI: 0.770–0.965) in the logistic regression analysis. Patients with flexion contracture ≥10° had higher PT (35.0 ± 6.6°) and SVA (82.2 ± 40.5 mm) than those with flexion contracture <10° (PT, 19.3 ± 9.0°; SVA, 42.4 ± 46.5 mm) (p = 0.001 and 0.028, respectively). The postoperative clinical outcome was correlated with the postoperative knee flexion angle and SVA (p = 0.036 and 0.020, respectively). The preoperative HKAA affected postoperative knee flexion angle, and the knee flexion contracture and clinical outcomes post-UKA were associated with PT and SVA, respectively. To predict outcomes for knee ROM and clinical scores after UKA, radiographic examination, including the sagittal spinopelvic parameters and the coronal view of the full lower extremity, is essential. [ABSTRACT FROM AUTHOR]

Anterior approach surgeons who utilize intraoperative fluoroscopy often try to match a preoperative radiograph as a reference for intraoperative cup position. Every degree of inaccuracy in tilt leads to a roughly 0.7° change in anteversion. This study aimed to determine how closely pelvic tilt (PT) is approximated intraoperatively when compared to preoperative anteroposterior (AP) radiographs. This was a retrospective review of 193 primary THA's done by 2 surgeons at an academic tertiary referral center between September 2021–January 2023. There were 24 patients excluded for distorted anatomy, post-traumatic arthritis, insufficient x-rays, or a sacroiliac joint that could not be visualized on film. Data collected included age and BMI. PT was calculated using the formula, Tilt = -(ln((B/A) x (1/0.483)))/0.051. Value A is the distance from the base of the SI joint to the superior margin of the obturator foramen; value B is the height of the obturator foramen. Mean preoperative PT was 0.2° versus intraoperative PT was 3.4° (p < 0.001). Mean absolute difference was 6.5°. 48% of patients (n = 81) had an absolute difference less than 5°, 31% (n = 52) between 5° and 10°, 14% (n = 24) between 10° and 15°, and 7% (n = 12) greater than 15°. There was no correlation between BMI or age and PT discrepancy. Of the patients, 21% had a discrepancy of 10° or greater between their preoperative radiographs and intraoperative fluoroscopic images. Surgeons should be aware of potential errors in cup positioning and be particularly diligent in high-risk cases. [ABSTRACT FROM AUTHOR]

Background: Low-density screw constructs yield significant radiographic and clinical improvements with reduced risk of neurological complications. This study aimed to investigate the relationship between coronal Cobb angle and pelvic incidence (PI) in the correction of adolescent idiopathic scoliosis (AIS) using a low-density construct, as well as the association between PI and functional outcomes. PATIENTS AND METHODS: This prospective cohort study involved 60 posteriorly instrumented AIS patients, aged 10–16 years, with Cobb angles ranging from 45° to 90° of various Lenke types. Radiological assessments were conducted pre- and postsurgery at 1, 3, 6, 12, and 24 months. Functional evaluation utilized the Scoliosis Research Society score form (SRS-30). Results: A positive correlation was observed between screw density and operation time, blood loss, and degree of correction with SRS change (P = 0.004). No correlation was found between screw density and hospital stay, loss of correction, correction rate, SRS change, change in PI, or Cobb angle. Conclusions: Correction of AIS through a posterior approach using a low-density construct can lead to satisfactory curve correction, impacting spinopelvic parameters. However, PI alone does not directly influence patient functional outcomes assessed by SRS-30. Low-density implant constructs reduce operative time, blood loss, costs, and complication risks.

BACKGROUND: Pelvic tilt, which is often seen in hip diseases, is also a common functional problem after total hip arthroplasty. OBJECTIVE: To investigate the mechanism of occurrence and recovery of pelvic tilt after unilateral total hip arthroplasty in patients with femoral head necrosis. METHODS: The clinical data of 100 patients with femoral head necrosis who underwent unilateral total hip arthroplasty in the Department of Femoral Head Necrosis, Bone Injury Center of First Affiliated Hospital of Guangzhou University of Chinese Medicine were collected retrospectively from June 2021 to February 2023. The patients were divided into three groups, namely, groups A (< 2°, n=48), B (2°-3°, n=34), and C (> 3°, n=18), according to the severity of pelvic tilt on postoperative 3 day. Statistical data were collected and compared between the pre- and postoperative periods of patients of these three groups in terms of the angle of the coronal plane of the pelvis tilt, the length of the gluteus medius muscles of the bilateral sides, the heights of the rotational centers of the femoral heads, the difference in the lengths of the gluteus medius muscles of the bilateral sides and the heights of the rotational centers of the femoral heads, and the ratio of changes in the angle of the pelvic tilt. Pearson correlation coefficient was used to examine the correlation between pelvic tilt angle and other indexes. RESULTS AND CONCLUSION: (1) Pelvic tilt aggravation occurred in the short term after surgery. (2) The ratio of change in pelvic tilt angle from postoperative 3 days to postoperative 1 month time period differed between the groups, with group C > group B > group A. There was a difference between group C and the other groups in the time period from postoperative 1 to postoperative 3 months, with the ratio of change being the smallest in group C. There was no difference in the ratio of change between the groups in the time period from postoperative 3 days to postoperative 3 months. (3) The difference in bilateral gluteus medius muscles decreased gradually after surgery, and there was no difference in the comparison of bilateral gluteus medius muscles in the time period from postoperative 3 months. (4) The difference between bilateral centers of rotation increased after surgery, and the difference between bilateral heights at 3 months after surgery was smaller than that before surgery. (5) The pelvic tilt angle at 3 days after surgery, the duration of the disease and the pelvic tilt angle at 3 months after surgery were significantly correlated (all P=0.000), and the difference between bilateral gluteus medius muscles before surgery and the pelvic tilt angle at 3 days after surgery was significantly correlated (P=0.006) (6) The functional pelvic tilt occurred in the patients with femoral head necrosis after total hip arthroplasty. Correction of the pelvic tilt after surgery was based on the adaptive restoration of the functional pelvic tilt angle after surgery. Functional pelvic tilt arises as a compensatory adaptation of the organism based on the short-term postoperative reconstruction of bony structures and the survival of cumulative soft tissue damage. [ABSTRACT FROM AUTHOR]

Abstract Background Fundamental morphologic differences between male and female pelvises are historically recognised. Despite this, little consideration has been given as to whether or not conventional positioning supports used for primary total hip arthroplasties (THAs) performed in the lateral position do an equally effective job of maintaining the intended set up position when comparing genders. Given that recent research has highlighted that unintended pelvic roll occurs commonly during hip surgery, and that such movement may have a mechanically-deleterious consequence upon final construct performance and complication rates, this study was undertaken to explore the differences in pelvic roll between genders. Methods The output of a high-precision, commercially-available, imageless intra-operative navigation system was prospectively-collected for 85 consecutive patients undergoing unilateral, primary THAs. These data were separated by gender and were utilised to determine differences in pelvic movement around a central sagittal axis. Results Demographic data were similar between genders, with no between-group differences in mean BMI (p = 0.09) or indication for surgery (p = 0.66), however participating males (mean 68.04) were slightly younger than females (mean 73.31). The mean anterior pelvic roll for females was 9.50°, and for males 8.68°. There were no statistically significant independent correlations observed between gender (p = 0.21) and pelvic roll. Conclusion The findings of this novel study do not suggest gender differences in the magnitude of unintended, intra-operative, anterior roll, even when corrected for BMI and surgical indication. Average roll of ~ 9° was demonstrated across both groups. An awareness of such positional change during THA surgery may reduce potentially-avoidable post-operative complications.

Abstract Background Abnormal posture (e.g. loss of lordosis) has been associated with the occurrence of musculoskeletal pain. Stretching tight muscles while strengthening the antagonists represents the most common method to treat the assumed muscle imbalance. However, despite its high popularity, there is no quantitative synthesis of the available evidence examining the effectiveness of the stretch-and-strengthen approach. Methods A systematic review with meta-analysis was conducted, searching PubMed, Web of Science and Google Scholar. We included controlled clinical trials investigating the effects of stretching or strengthening on spinal and lumbopelvic posture (e.g., pelvic tilt, lumbar lordosis, thoracic kyphosis, head tilt) in healthy individuals. Effect sizes were pooled using robust variance estimation. To rate the certainty about the evidence, the GRADE approach was applied. Results A total of 23 studies with 969 participants were identified. Neither acute (d = 0.01, p = 0.97) nor chronic stretching (d=-0.19, p = 0.16) had an impact on posture. Chronic strengthening was associated with large improvements (d=-0.83, p = 0.01), but no study examined acute effects. Strengthening was superior (d = 0.81, p = 0.004) to stretching. Sub-analyses found strengthening to be effective in the thoracic and cervical spine (d=-1.04, p = 0.005) but not in the lumbar and lumbopelvic region (d=-0.23, p = 0.25). Stretching was ineffective in all locations (p > 0.05). Conclusion Moderate-certainty evidence does not support the use of stretching as a treatment of muscle imbalance. In contrast, therapists should focus on strengthening programs targeting weakened muscles.

Introduction: Studies describing the relationship between the hip and spine have reported that corrective spinal surgery for adult spinal deformity (ASD) affects the orientation of the acetabulum. However, the extent to which spinal correction in ASD affects acetabular anteversion in the standing position is unclear, especially after total hip arthroplasty, for which dislocation is a concern. The purpose of this study was to evaluate changes in anterior acetabular coverage in the upright position due to extensive correction surgery for ASD. Methods: Thirty-six consecutive patients who had undergone spinal corrective surgery from the thoracolumbar region to the pelvis were enrolled and evaluated. The ventral-central-acetabular (VCA) angle and anterior acetabular head index (AAHI) were measured with a false-profile view to evaluate the relationship between acetabular anteversion in the standing position and spinopelvic parameters before and after surgery. The spinopelvic parameters measured included thoracic kyphosis, pelvic incidence, pelvic tilt (PT), sacral slope, lumbar lordosis (LL), sagittal vertical axis, and global tilt. Results: The VCA angle and AAHI were significantly increased after spinal deformity correction (p

Introduction: Spinopelvic mobility drives functional acetabular position, influencing dislocation risk after total hip arthroplasty (THA). Patients have been described as "stuck sitting" or "stuck standing" based on pelvic tilt (PT). We hypothesised that some patients are "stuck in the middle," meaning their PT changes minimally from sitting to standing – increasing their risk of dislocation. Methods: We reviewed 195 patients with standing and sitting whole body radiographs prior to THA. Standing anterior pelvic plane tilt (APPT) and standing and sitting sacral slope (SS) were measured and used to calculate sitting APPT. Normal standing and sitting were defined as APPT >−10° and <−20°, respectively. Spinal stiffness was classified as <10° change in sacral slope between sitting and standing. Patients were categorised as: (A) able to fully sit and stand; (B) "stuck sitting" - able to fully sit; unable to fully stand; (C) "stuck standing" - able to fully stand; unable to fully sit; or (D) "stuck in the middle" - unable to sit or stand fully. Results: 84 patients could sit and stand normally (A), 22 patients were stuck sitting (B), 76 patients were stuck standing (C), and 13 patients were stuck in the middle (D). While 111 patients (56.9%) were considered stuck, only 58 patients (29.7%) met criteria for spinal stiffness. Discussion: We identified a subset of patients with stiff spines and abnormal PT in both sitting and standing, including 37.1% of patients who would be classified as "stuck sitting" based only on standing radiographs. Placing acetabular components in less than anatomic anteversion in these patients may increase posterior dislocation risk. [ABSTRACT FROM AUTHOR]

Background: Understanding spinal sagittal balance is crucial for assessing and treating spinal deformities in pediatric populations. Objective: The aim of the present observational study is to examine the parameters of sagittal alignment of the regional spine and spinopelvic region in asymptomatic pediatric populations and the characteristics of these parameters with age and sex. Methods: We enrolled 217 participants, consisting of 112 males (51.6%) and 105 females (48.4%), aged between 4 and 15 years, with an average age of 12.19 years. Pelvic incidence, pelvic tilt, sacral slope, lumbar lordosis, thoracic kyphosis, T1 slope, C7 slope, cervical sagittal vertical axis, and C2–7 Cobb angle were measured. Three spine surgeons conducted radiographic measurements utilizing the PACS software. The measurement reliability was assessed through ICCs. Results: Our results show significant age-related changes in pelvic tilt and cervical sagittal vertical axis, with notable gender differences in pelvic tilt, lumbar lordosis, and thoracic kyphosis. Girls have larger PT, boys have larger cSVA. PI, PT, and cSVA also differ among different age groups. Correlation analysis shows that a series of relationships that align with adult population patterns between pelvic incidence, pelvic tilt, sacral slope, lumbar lordosis, and thoracic kyphosis. Conclusion: Significant variations in PT and cSVA across diverse age cohorts highlights notable disparities in the distribution of PT and cSVA values within the pediatric population. Gender-based differences in PT, LL, and TK and correlation in spinopelvic parameter could enhances our understanding of compensatory mechanisms. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the actual change in clinical hip pain and hip migration after operation for non-ambulatory flaccid neuromuscular (NM) scoliosis and investigate whether there is an association between hip migration and coronal/sagittal pelvic tilt (CO-PT/SA-PT). Patients and methods: This retrospective, single-center, observational study evaluated a total of 134 patients with non-ambulatory flaccid neuromuscular scoliosis who underwent surgery performed by a single surgeon between 2003 and 2020, with at least 2 years of follow-up period. Operation procedures were conducted in two stages, beginning with L5–S1 anterior release followed by posterior fixation. Radiologic parameters were measured at preoperative, immediate postoperative, and last follow-up periods with clinical hip pain and clinical hip dislocation events. Results: The significant improvements occurred in various parameters after correction surgery for NM scoliosis, containing Cobb's angle of major curve and CO-PT. However, Reimer's hip migration percentage (RMP) was increased on both side of hip (High side, 0.23 ± 0.16 to 0.28 ± 0.21; Low side, 0.20 ± 0.14 to 0.23 ± 0.18). Hip pain and dislocation events were also increased (Visual analog scale score, 2.5 ± 2.3 to 3.6 ± 2.6, P value < 0.05; dislocation, 6–12). Logistic regression analysis of the interactions between ΔRMP(High) and the change of sagittal pelvic tilt (ΔSA-PT) after correction reveals a significant negative association. (95% CI 1.003–1.045, P value = 0.0226). Conclusions: In cases of non-ambulatory flaccid NM scoliosis, clinical hip pain, and subluxation continued to deteriorate even after correction of CO-PT. There was a relationship between the decrease in SA-PT, and an increase in hip migration percentage on high side, indicating the aggravation of hip subluxation. [ABSTRACT FROM AUTHOR]

To examine the effect of induced posterior pelvic tilt (changes in pelvic kinematics) on serratus anterior, lower trapezius, and upper trapezius electromyographic activity, and thoracic posture during arm elevation in individuals with rounded shoulder. Materials and methods Thirty healthy volunteers (26 male and 4 female participants) with rounded shoulder, their mean age 22.80±3.2, BMI 23.51± 3.9 were evaluated for both thoracic and pelvic posture using a 9-camera, 3-dimensional motion capture system (Vicon Nexus version 2, Oxford, UK), serratus anterior, lower trapezius, and upper trapezius electromyographic activity. The measurements were recorded in different six experimental conditions while inducing posterior pelvic tilt during arm elevation. For the six experimental conditions involving arm elevation, repeated measures analysis of variance within-subjects was used to examine the changes in electromyographic activities of lower trapezius, upper trapezius, and serratus anterior due to pelvic kinematics' changes whereas paired t-tests were used to examine the changes in the thoracic posture in response to pelvic kinematics' changes and to compare the pelvic tilt angle between the habitual relaxed position and the induced posterior tilt position. Results Upper trapezius, serratus anterior, and lower trapezius electromyographic activity significantly increased in response (changes in pelvic kinematics) induced posterior pelvic tilt (35:40%) of the maximal posterior pelvic tilt, although there were no apparent alterations in thoracic posture. (p>0.05). Conclusion Induced posterior pelvic tilt, (35:40%) of the maximum, resulted in an increase in the electromyographic activity of serratus anterior, lower trapezius, upper trapezius, which reflects that changes in pelvic kinematic could alter scapular muscles activity, so comprehensive examination of pelvic posture is required in both preventive and treatment programs of shoulder complex injuries. Meanwhile, no significant effect was reported on thoracic posture. [ABSTRACT FROM AUTHOR]

BACKGROUND: Osteoporotic vertebral compression fracture is a common fracture secondary to osteoporosis. At present, there is no effective prediction index and method for osteoporotic vertebral compression fracture. OBJECTIVE: To investigate the predictive effect of the comprehensive index of lumbar vertebral body bone strength on osteoporotic vertebral compression fracture. METHODS: 233 patients with osteoporosis were divided into a fracture group and a non-fracture group according to whether a vertebral fracture occurred. The demography, body mass index, vertebral bone mineral density and other details were collected. Lateral X-ray films of the lumbar spine were photographed. The vertebral body width, vertebral body length, sacral slope, pelvic tilt, pelvic incidence, lumbar compressive strength index and the lumbar impact strength index were measured, calculated, and analyzed by univariate and multivariate, and the receiver operating characteristic curve was analyzed. The survival analysis was conducted according to the cut-off value. RESULTS AND CONCLUSION: (1) All patients were followed up for 2-4 years, with an average of 3.1 years. During the follow-up period, 99 cases (38 cases of L1 vertebral body, 61 cases of L2 vertebral body) had fractures (fracture group), and 134 cases (52 cases of L1 vertebral body, 82 cases of L2 vertebral body) had no fractures (non-fracture group). Univariate analysis showed that there was no significant difference in age, sex, height, body mass, body mass index and fracture segment between the two groups (P > 0.05). (2) Lumbar compressive strength index and lumbar impact strength index in the fracture group were lower than those in the non-fracture group (P<0.05). Pelvic incidence and pelvic tilt in the fracture group were higher than those in the non-fracture group (P<0.05). (3) Multivariate analysis showed that lumbar compressive strength index, lumbar impact strength index and pelvic tilt were risk factors for osteoporotic vertebral compression fractures (P<0.05). (4) Receiver operating characteristic curve analysis showed that the cutoff values of vertebral bone mineral density, lumbar compressive strength index, lumbar impact strength index, pelvic tilt and pelvic incidence were 0.913 5 g/cm2, 1.932, 0.903, 21.5° and 55°, respectively; areas under the curve were 0.630, 0.800, 0.911, 0.633 and 0.568, respectively. (5) According to the survival analysis (with osteoporotic vertebral compression fracture as the end point), the average survival time of the patients with lumbar impact strength index ≥0.903 was significantly longer than that of the patients with lumbar impact strength index < 0.903 (P<0.05). (6) These findings conclude that the comprehensive index of lumbar vertebral body bone strength is more accurate than the bone mineral density of the vertebral body and spine-pelvis sagittal parameters in predicting osteoporotic vertebral compression fractures, which is helpful for early prevention and treatment of osteoporotic vertebral compression fractures. [ABSTRACT FROM AUTHOR]

Introduction Methods Results Conclusions The aim was to determine which immobilisation device improved inter‐fraction reproducibly of pelvic tilt and required the least pre‐treatment setup and planning interventions.Sixteen patients were retrospectively reviewed, eight immobilised using the BodyFIX system (BodyFIX®, Elekta, Stockholm, Sweden) and eight using the Butterfly Board (BB) (Bionix Radiation Therapy, Toledo, OH, USA). The daily pre‐treatment images were reviewed to assess setup variations between each patient and groups for pelvic tilt, pubic symphysis, sacral promontory and the fifth lumbar spine (L5).Compared with the planning CT, pelvic tilt for most patients was within ±2° using the BodyFIX and ± 4° for the BB. The Butterfly Board had a slightly higher variance both for patient‐to‐patient (standard deviation of the systematic error) and day‐to‐day error (standard deviation of the random error). Variance in position between individual patients and the two stabilisation devices were minimal in the anterior–posterior (AP) and superior–inferior (SI) direction for the pubic symphysis, sacral promontory and L5 spine. Re‐imaged fractions due to pelvic tilt reduced by about half when BodyFIX was used (39.1% BB, 19.4% BodyFIX). One patient treated with the BB required a re‐scan for pelvic tilt. Three patients required a re‐scan for body contour variations (two using BodyFIX and one with the BB).BodyFIX resulted in a more accurate inter‐fraction setup and efficient treatment and is used as the standard stabilisation for gynaecological patients at our centre. It reduced the pelvic tilt variance and reduced the need for re‐imaging pre‐treatment by half. [ABSTRACT FROM AUTHOR]

This study aimed to assess acute and residual changes in sprint-related hamstring injury (HSI) risk factors after a football (soccer) match, focusing on recovery within the commonly observed 72-h timeframe between elite football matches. We used a multifactorial approach within a football context, incorporating optical and ultrastructural microscopic analysis of BFlh (biceps femoris long head) muscle fibres, along with an examination of BFlh fibre composition. Changes in sprint performance-related factors and HSI modifiable risk factors were examined until 3 days after the match (MD +3) in 20 football players. BFlh biopsy specimens were obtained before and at MD +3 in 10 players. The findings indicated that at MD +3, sprint-related performance and HSI risk factors had not fully recovered, with notable increases in localized BFlh fibre disruptions. Interestingly, match load (both external and internal) did not correlate with changes in sprint performance or HSI risk factors nor with BFlh fibre disruption. Furthermore, our study revealed a balanced distribution of ATPase-based fibre types in BFlh, with type-II fibres associated with sprint performance. Overall, the results suggest that a 72-h recovery period may not be adequate for hamstring muscles in terms of both HSI risk factors and BFlh fibre structure following a football match. [ABSTRACT FROM AUTHOR]

Background: Abnormal posture (e.g. loss of lordosis) has been associated with the occurrence of musculoskeletal pain. Stretching tight muscles while strengthening the antagonists represents the most common method to treat the assumed muscle imbalance. However, despite its high popularity, there is no quantitative synthesis of the available evidence examining the effectiveness of the stretch-and-strengthen approach. Methods: A systematic review with meta-analysis was conducted, searching PubMed, Web of Science and Google Scholar. We included controlled clinical trials investigating the effects of stretching or strengthening on spinal and lumbopelvic posture (e.g., pelvic tilt, lumbar lordosis, thoracic kyphosis, head tilt) in healthy individuals. Effect sizes were pooled using robust variance estimation. To rate the certainty about the evidence, the GRADE approach was applied. Results: A total of 23 studies with 969 participants were identified. Neither acute (d = 0.01, p = 0.97) nor chronic stretching (d=-0.19, p = 0.16) had an impact on posture. Chronic strengthening was associated with large improvements (d=-0.83, p = 0.01), but no study examined acute effects. Strengthening was superior (d = 0.81, p = 0.004) to stretching. Sub-analyses found strengthening to be effective in the thoracic and cervical spine (d=-1.04, p = 0.005) but not in the lumbar and lumbopelvic region (d=-0.23, p = 0.25). Stretching was ineffective in all locations (p > 0.05). Conclusion: Moderate-certainty evidence does not support the use of stretching as a treatment of muscle imbalance. In contrast, therapists should focus on strengthening programs targeting weakened muscles. Key Points: • Stretching of tight muscles and strengthening of weak muscles is popular in treating muscular imbalance of the pelvis and spine. While combined interventions have previously been meta-analyzed and shown to be effective, the effectiveness of both used in isolation has not been investigated. • This meta-analysis found no effects of stretching on posture while strengthening can improve imbalances/posture. • Additional studies including higher stretching volumes and intensities are warranted. [ABSTRACT FROM AUTHOR]

Understanding the biomechanical relationship between the spine and the pelvis is important for the management of symptomatic lumbar disease. There are several different metrics that may be used to evaluate the spine in the sagittal plane. The aim of this study is to compare spinopelvic parameters and global sagittal angle (GSA) in a cohort of patients with upper lumbar disc herniations (ULDH) to identify a correlation between the pelvic incidence (PI) and GSA with ULDH. Eighty-six patients with ULDH and 86 asymptomatic control group underwent whole body biplanar stereographs- and magnetic resonance imaging. The spinopelvic parameters and GSA were measured. PI, sacral slope (SS), lumbar lordosis (LL), and thoracic kyphosis (TK) were all significantly lower than in the control group (p < 0.01) but there was no difference in the pelvic tilt (PT). The two groups were divided into subgroups. PI in the T12–L1 and L1–L2 level groups were significantly smaller than in the control group (p < 0.05). Also, there was a significant difference in TK and LL between the L3–L4 level and control group (p < 0.05), but there was no statistically significant difference in PT between all levels and the control group. This study demonstrated a unique correlation between several spinopelvic parameters and GSA and the occurrence of ULDH. Lower PI, SS, and LL in T12–L1 and L1–L2 levels indicates a flat lumbar spine which may increase mechanical stress at these levels, thereby leading to disc herniation. [ABSTRACT FROM AUTHOR]

Purpose: Transitional lumbosacral vertebrae (TLSV) are a congenital anomaly of the lumbosacral region that is characterized by the presence of a vertebra with morphological properties of both the lumbar and sacral vertebrae, with a prevalence of up to 36% in asymptomatic patients and 20% in adolescent idiopathic scoliosis patients. In patients with TLSV, because of these morphological changes and the different numbers of lumbar vertebrae, there are two optional reference sacral endplates that can be selected intently or inadvertently to measure the spinopelvic parameters: upper and lower endplates. The spinopelvic parameters measured using the upper and lower endplates are significantly different from each other as well as from the normative values. Therefore, the selection of a reference endplate changes the spinopelvic parameters, lumbar lordosis (LL), and surgical goals, which can result in surgical over- or under-correction. Because there is no consensus on the selection of sacral endplate among these patients, it is unclear as to which of these parameters should be used in diagnosis or surgical planning. The present study describes a standardization method for measuring the spinopelvic parameters and LL in patients with TLSV. Methods: Upper and lower endplate spinopelvic parameters (i.e., pelvic incidence [PI], sacral slope [SS], and pelvic tilt) and LL of 108 patients with TLSV were measured by computed tomography. In addition, these parameters were measured for randomly selected subjects without TLSV. The PI value in the TLSV group, which was closer to the mean PI value of the control group, was accepted as valid and then used to create an optimum PI (OPI) group. Finally, the spinopelvic parameters and LL of the OPI and control groups were compared. Results: Except for SS, all spinopelvic parameters and LL were comparable between the OPI and control groups. In the OPI group, 60% of the patients showed valid upper endplate parameters, and 40% showed valid lower endplate parameters. No difference was noted in the frequency of valid upper or lower endplates between the sacralization and lumbarization groups. Both the OPI and control groups showed nearly comparable correlations between their individual spinopelvic parameters and LL, except for PI and LL in the former. Conclusions: Because PI is unique for every individual, the endplate whose PI value is closer to the normative value should be selected as the reference sacral endplate in patients with TLSV. [ABSTRACT FROM AUTHOR]

Introduction: Many risk factors for proximal junctional kyphosis (PJK) have been reported in the literature, especially sagittal alignment modifications, but studies on pelvic tilt (PT) variations and its influence on PJK are missing. Aim of this study was to analyze the influence of pelvic tilt correction, after long fusion surgery for ASD patients, on PJK occurrence. Methods: A monocentric retrospective study was conducted on prospectively collected data, including 76 patients, operated with fusion extending from the thoraco-lumbar junction to the ilium. Radiologic parameters were measured on fullspine standing radiographs preoperatively, postoperatively (<6 months) and at latest follow-up (before revision surgery or >2 years). All parameters were analyzed comparing patients with PJK (group "PJK") and without PJK (group "no PJK"). A further analysis compared patients with low (PT/PI<25th percentile, LowPT group) and high (PT/PI>75th percentile, HighPT group) preoperative pelvic tilt. Results: « PJK » patients had a greater lumbar lordosis and thoracic kyphosis correction (p=0,03 et <0,001 respectively) compared to the "no PJK" patients. Pelvic tilt was significantly lower postoperatively in the "PJK" group (p=0,03). Patients from the HighPT PJK group were significantly more corrected than patients from the HighPT noPJK group (p=0,003). Conclusion: Through the analysis of 76 patients, we showed that pelvic tilt did not seem to play a role in the setting of PJK after ASD surgery. Decreasing PT after surgery could be an element to watch out for in patients with PJK risk factors. [ABSTRACT FROM AUTHOR]

Background: The goal of this study was to better understand the variation of femoral neck version according to spinopelvic and lower limb 3D alignment using biplanar X-rays in standing position. Methods: This multicentric study retrospectively included healthy subjects from previous studies who had free-standing position biplanar radiographs. Subjects were excluded if they presented spinal or any musculo-skeletal deformity, and reported pain in the spine, hip or knee. Age, sex, and the following 3D-reconstructed parameters were collected: spinal curvatures, pelvic parameters, sagittal vertical axis (SVA), T1 pelvic angle (TPA), spino-sacral angle (SSA), femoral torsion angle (FTA), sacro-femoral angle (SFA), knee flexion angle (KA), ankle angle (AA), pelvic shift (PS) and ankle distance. Femoral neck version angle (FVA) was calculated between horizontal plane projection of the bi-coxo-femoral axis and the line passing through the femoral neck barycenter and femoral head center. Analysis according to age subsets was performed. Results: A total of 400 subjects were included (219 females); mean age was 29 ± 18 years (range: 4–83). Subjects with high pelvic tilt values presented significantly higher FVA than average and low-PT individuals, respectively, 7.8 ± 7.1°, 2 ± 9° and 2.1 ± 9.5° (p < 0.001). These subjects also presented lower lumbar lordosis values and higher acetabulum anteversion in the horizontal plane than the two other groups. SVA correlation with FVA was weaker (r = 0.1, p = 0.03) than SSA and TPA (r = − 0.3 and r = 0.3, respectively, p < 0.001). A strong correlation was found with femoral torsion (r = 0.5, p < 0.001). SFA (r = − 0.3, p < 0.001), pelvic shift (r = 0.2, p < 0.001) and ankle distance (r = 0.3, p < 0.001) were also significantly correlated. Multivariate analysis confirmed significant association of age, pelvic tilt, lumbar lordosis, pelvic shift, ankle distance and femoral torsion with FVA. Conclusion: Patients with lower lumbar lordosis present pelvic retroversion which induces a higher femoral neck version. This finding may help positioning implants in total hip replacement procedures. Higher pelvic shift, age, male gender and increased femoral torsion were also correlated with higher FVA. Level of evidence: II (Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding). [ABSTRACT FROM AUTHOR]

IntroductionWhile pedaling, cyclists rest their pelvis on the saddle, generating pressures on it. The pressures generated on the saddle are influenced by several factors. This study aimed to evaluate whether the flexibility of hamstring and lower back muscles could be considered a predictor of pressures in the anterior region (PAR) on the saddle.MethodsFor this study, 15 young off-road Italian cyclists (11m, 4f) aged 13–16 (Italian Federation categories: ES1, ES2, AL1, AL2) were recruited. Each participant was administered the V sit-and-reach (VSR) to measure the hamstring and lower back muscles flexibility. Subsequently, after performing a bike fitting, the saddle pressures during pedaling at three different intensities (100, 140, 180 W), with participants on their own bike installed on specific bike roller, were recorded. The parameters considered for statistical analysis were front pressure (%) and back pressure (%).ResultsThe hamstring and lower back muscles flexibility, as result of the VSR test, was a predictor of saddle PAR at 100 W (R2 = 0.362, p = 0.018), at 140 W (R2 = 0.291, p = 0.038), and at 180 W (R2 = 0.349, p = 0.020) of pedaling intensity.ConclusionHigher values of the VSR could predict lower values of the pressures exerted in the front region of the saddle. The hamstring and lower back muscles flexibility may be considered a predictor of PAR on the saddle.

Background: Every degree of change in pelvic tilt (PT) leads to a 0.7° change in anteversion and a 0.3° change in inclination. This study aimed to determine the significance of contralateral hip arthritis on changes in PT using preoperative and postoperative anteroposterior radiographs. Methods: There were 193 primary total hip arthroplasties done by 2 surgeons at a single academic tertiary referral center reviewed between September 2021 and January 2023. PT was calculated as Tilt = −(ln[(B/A) × (1/0.483)]) / 0.051. Value A is the distance from the base of the SI joint to the superior margin of the obturator foramen; value B is the height of the obturator foramen. After exclusions, contralateral hips were identified as being normal (n = 75), arthritic (n = 39) (Tönnis grade 3/4), replaced (n = 34), or having undergone simultaneous bilateral total hip arthroplasty (n = 5) on postoperative films. Difference in PT was measured between preoperative and postoperative films taken 1-3 months after surgery. Analyses for statistical significance were calculated using t-tests and one-way analysis of variance. Results: Average change in PT in patients with normal contralateral hips was −5.2° with an absolute mean difference of 7.6°, −1.5° for arthritic contralateral hips with an absolute mean difference of 5.0°, −1.6° for replaced contralateral hips with a mean absolute difference of 4.3°, and 2.2° for bilateral hips with a mean absolute difference of 2.6° (P < .01). Conclusions: Differences in postoperative PT changes between healthy, arthritic, and replaced contralateral hip study groups were significant. Changes in preoperative to postoperative tilt may have implications for optimal cup placement.

Low back pain (LBP) is an economic and physically disabling burden on individuals and society. With 70% of cases classed as non-specific, there is a need for further research into the causes and consequences associated. The involvement of postural balance in musculoskeletal conditions is gaining increasing interest in research and health practice. However, there is a lack of literature surrounding LBP and posture in distal segments of the body. The current study investigated scapula positioning in those with non-specific LBP. Scapula angle of rotation, scapula protraction, and scapula elevation were assessed in nine participants with chronic non-specific LBP and compared with that of nine asymptomatic controls (aged 18–60 years). The degree of pelvic tilt was assessed across both groups as a secondary outcome measure. No difference was identified between the two sample groups for scapula angle of rotation (p = 0.707), protraction (p = 0.755), or elevation (p = 0.691). Anterior pelvic tilt was greater in those with LBP (p = 0.046), supporting previous literature. The findings for the scapula position are novel, given that research in this field is limited. It is concluded that there is no change in scapula positioning in those with non-specific LBP, but there is an increased anterior pelvic tilt. [ABSTRACT FROM AUTHOR]

Background: Accurate pre-surgical templating of the pelvic tilt (PT) angle is essential for hip and spine surgeries, yet the reliability of PT annotations is often compromised by human error, inherent subjectivity, and variations in radiographic quality. This study aims to identify challenges leading to inadequate annotations at a landmark dimension and evaluating their impact on PT. Methods: We retrospectively collected 115 consecutive sagittal radiographs for the measurement of PT based on two definitions: the anterior pelvic plane and a line connecting the femoral head's centre to the sacral plate's midpoint. Five annotators engaged in the measurement, followed by a secondary review to assess the adequacy of the annotations across all the annotators. Results: The outcomes indicated that over 60% images had at least one landmark considered inadequate by the majority of the reviewers, with poor image quality, outliers, and unrecognized anomalies being the primary causes. Such inadequacies led to discrepancies in the PT measurements, ranging from −2° to 2°. Conclusion: This study highlights that landmarks annotated from clear anatomical references were more reliable than those estimated. It also underscores the prevalence of suboptimal annotations in PT measurements, which extends beyond the scope of traditional statistical analysis and could result in significant deviations in individual cases, potentially impacting clinical outcomes. [ABSTRACT FROM AUTHOR]

The correction of postural weaknesses through the better positioning of the pelvis is an important approach in sports therapy and physiotherapy. The pelvic position in the sagittal plane is largely dependent on the muscular balance of the ventral and dorsal muscle groups. The aim of this exploratory study was to examine whether healthy persons use similar muscular activation patterns to correct their pelvic position or whether there are different motor strategies. The following muscles were recorded in 41 persons using surface electromyography (EMG): M. trapezius pars ascendens, M. erector spinae pars lumbalis, M. gluteus maximus, M. biceps femoris, M. rectus abdominis, and M. obliquus externus. The participants performed 10 voluntary pelvic movements (retroversion of the pelvis). The anterior pelvic tilt was measured videographically via marker points on the anterior and posterior superior iliac spine. The EMG data were further processed and normalized to the maximum voluntary contraction. A linear regression analysis was conducted to assess the relationship between changes in the pelvic tilt and muscle activities. Subsequently, a Ward clustering analysis was applied to detect potential muscle activation patterns. The differences between the clusters and the pelvic tilt were examined using ANOVA. Cluster analysis revealed the presence of four clusters with different muscle activation patterns in which the abdominal muscles and dorsal muscle groups were differently involved. However, the gluteus maximus muscle was involved in every activation pattern. It also had the strongest correlation with the changes in pelvic tilt. Different individual muscle patterns are used by different persons to correct pelvic posture, with the gluteus maximus muscle apparently playing the most important role. This can be important for therapy, as different muscle strategies should be trained depending on the individually preferred motor patterns. [ABSTRACT FROM AUTHOR]

Accurate and reliable estimation of the pelvic tilt is one of the essential pre-planning factors for total hip arthroplasty to prevent common post-operative complications such as implant impingement and dislocation. Inspired by the latest advances in deep learning-based systems, our focus in this paper has been to present an innovative and accurate method for estimating the functional pelvic tilt (PT) from a standing anterior–posterior (AP) radiography image. We introduce an encoder–decoder-style network based on a concurrent learning approach called VGG-UNET (VGG embedded in U-NET), where a deep fully convolutional network known as VGG is embedded at the encoder part of an image segmentation network, i.e., U-NET. In the bottleneck of the VGG-UNET, in addition to the decoder path, we use another path utilizing light-weight convolutional and fully connected layers to combine all extracted feature maps from the final convolution layer of VGG and thus regress PT. In the test phase, we exclude the decoder path and consider only a single target task i.e., PT estimation. The absolute errors obtained using VGG-UNET, VGG, and Mask R-CNN are 3.04 ± 2.49, 3.92 ± 2.92, and 4.97 ± 3.87, respectively. It is observed that the VGG-UNET leads to a more accurate prediction with a lower standard deviation (STD). Our experimental results demonstrate that the proposed multi-task network leads to a significantly improved performance compared to the best-reported results based on cascaded networks. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to explore the relationships between lumbar lordosis (LL) correction and improvement of postoperative global sagittal alignment and to establish corresponding linear regressions to predict the change in global tilt (GT) based on the corrected LL following adult spinal deformity (ASD) surgery. Methods: A total of 240 ASD patients who underwent lumbar correction were enrolled in this multicentre study. The following sagittal parameters were measured pre- and postoperatively: thoracic kyphosis (TK), LL, upper and lower LL (ULL and LLL), pelvic tilt (PT), sagittal vertical axis (SVA) and GT. The correlations among the changes in GT (△GT), SVA (△SVA), PT (△PT), TK (△TK), LL (△LL), ULL (△ULL) and LLL (△LLL) were assessed, and linear regressions were conducted to predict △GT, △SVA, △PT and △TK from △LL, △ULL and △LLL. Results: △LL was statistically correlated with △GT (r = 0.798, P < 0.001), △SVA (r = 0.678, P < 0.001), △PT (r = 0.662, P < 0.001) and △TK (r = − 0.545, P < 0.001), and the outcomes of the linear regressions are: △GT = 3.18 + 0.69 × △LL (R2 = 0.636), △SVA = 4.78 + 2.57 × △LL (R2 = 0.459), △PT = 2.57 + 0.34 × △LL (R2 = 0.439), △TK = 7.06–0.43 × △LL (R2 = 0.297). In addition, △LLL had more correlations with △GT, △SVA and △PT, while △ULL had more correlations with △TK. Conclusion: Surgical correction of LL could contribute to the restoration of global sagittal morphology following ASD surgery. These models were established to predict the changes in sagittal parameters, in particular △GT, determined by △LL, which has not been previously done and may help to customize a more precise correction plan for ASD patients. [ABSTRACT FROM AUTHOR]

Computational models of the hip often omit patient-specific functional orientation when placing imaging-derived bony geometry into anatomic landmark-based coordinate systems for application of joint loading schemes. The purpose of this study was to determine if this omission meaningfully alters computed contact mechanics. Discrete element analysis models were created from non-weightbearing (NWB) clinical CT scans of 10 hip dysplasia patients (11 hips) and oriented in the International Society of Biomechanics (ISB) coordinate system (NWB-ISB). Three additional models were generated for each hip by adding patient-specific stance information obtained via weightbearing CT (WBCT) to each ISB-oriented model: (1) patient-specific sagittal tilt added (WBCT-sagittal), (2) coronal and axial rotation from optical motion capture added to (1; WBCT-combo), and (3) WBCT-derived axial, sagittal, and coronal rotation added to (1; WBCT-original). Identical gait cycle loading was applied to all models for a given hip, and computed contact stress and contact area were compared between model initialization techniques. Addition of sagittal tilt did not significantly change whole-joint peak (p = 0.922) or mean (p = 0.871) contact stress or contact area (p = 0.638). Inclusion of motion-captured coronal and axial rotation (WBCT-combo) decreased peak contact stress (p = 0.014) and slightly increased average contact area (p = 0.071) from WBCT-sagittal models. Including all WBCT-derived rotations (WBCT-original) further reduced computed peak contact stress (p = 0.001) and significantly increased contact area (p = 0.001). Variably significant differences (p = 0.001–1.0) in patient-specific acetabular subregion mechanics indicate the importance of functional orientation incorporation for modeling applications in which local contact mechanics are of interest. [ABSTRACT FROM AUTHOR]

Background and purpose: Arthroplasty surgeons traditionally assess cup orientation after total hip arthroplasty (THA) on supine radiographs. Contemporary hip–spine analyses provide information on standing, functional cup orientation. This study aims to (i) characterize cup orientations when supine and standing; (ii) determine orientation differences between postures; and (iii) identify factors associated with magnitude of orientation differences. Methods: This is a 2-center, multi-surgeon, prospective, consecutive cohort study. 419 primary THAs were included (57% women; mean age: 64 years, standard deviation [SD] 11). All patients underwent supine and standing antero-posterior pelvic and lateral spinopelvic radiographs. Cup orientation and spinopelvic parameters were measured. Target cup orientation was defined as inclination/anteversion of 40°/20° ± 10°. A change in orientation (Δinclination/Δanteversion) between postures > 5° was defined as clinically significant. Variability was defined as 2 x SD. Results: Inclination increased from 40° (supine) to 42° (standing) corresponding to a Δinclination of 2° (95% confidence interval [CI] 2–3). Anteversion increased from 25° (supine) to 30° (standing) corresponding to a Δanteversion of 5° (CI 5–6). When supine, 69% (CI 65–74) of THAs were within target, but only 44% (CI 39–49) were within target when standing, resulting in a further 26% (CI 21–30) being out of target when standing. From supine to standing, a clinically significant change in anteversion (> 5°) was seen in 47% (CI 42–52) of cases. Δanteversion was higher in women than in men (6°, CI 5–7 vs 5°, CI 4–5) corresponding to a difference of 1° (CI 1–2), which was dependent on tilt change, standing cup anteversion, age, and standing pelvic tilt. Conclusion: Cup inclination and version increase upon standing but significant variability exists due to patient factors.

Background: Degenerative spondylolisthesis (DS) is associated with altered radiological spinopelvic parameters (SPP) which leads to poor patient-reported clinical outcomes. Transforaminal lumbar interbody fusion (TLIF) is performed for DS however, its ability to adequately restore SPP is not well reported. The study was performed to determine the effect of TLIF on the SPP and its correlation to patient-reported functional outcomes. Materials and Methods: Prospective, consecutive recruitment of patients was performed, with single and double-level DS treated with TLIF between March 2019 to March 2020 with a 2-year follow-up. Functional outcomes were measured using the visual analog score (VAS) score, Oswestry Disability Index (ODI) score, and SF-36 questionnaire. SPPs (pelvic tilt [PT], pelvic inclination, sacral slope [SS], lumbar lordosis [LL], and PI-LL mismatch) were recorded. The correlation between SPP and functional outcomes was analyzed using Spearman’s correlation coefficient. Results: A total of 40 patients were included in the final analysis. Significant improvement in VAS score, ODI score, and SF-36 score was observed (P < 0.05 for all) at 2 years follow-up. No significant difference was noted in the PI, LL, and SS following surgery (P > 0.05). A significant change in mean PT from 15.76° to 19.53° was noted (P = 0.023). The mean PI-LL mismatch improved from 14.7° to 11.2° which was statistically significant (P < 0.05). However, no significant correlation between ODI score with PT (r = 0.156) and post-op PI-LL mismatch (r = 0.105) could be demonstrated. Conclusion: TLIF led to satisfactory improvement in the patient-reported outcomes, PT, and PI-LL mismatch. However, the improvement of the SPP did not correlate with improvements in the ODI score.

Introduction: In this study, we aim to estimate the natural standing sagittal alignment in patients with adult spinal deformity (ASD), firstly by investigating the normative values of anatomical pelvic parameters based on the anterior pelvic plane (APP) in a healthy population, and to clarify the relationships between the anatomical and positional pelvic parameters in standing position. Methods: The images of biplanar slot-scanning full-body stereoradiography in 140 healthy Japanese volunteers (mean age, 39.5 years; 59.3% female) were examined. In addition to three-dimensional measurements including pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT), the APP angle (APPA; anterior tilting=positive) was measured as the angle between the APP and the vertical line using the two-dimensional lateral image. Anatomical SS and PT (aSS and aPT) were calculated as the angles of SS and PT in reference to APP. Results: The mean (range) values of APPA, aSS, and aPT were determined to be 0.7° (−16.8°/15.5°), 36.8° (18.3°/64.9°), and 13.2° (−0.6°/28.7°), respectively. Moreover, SS was found to be significantly correlated with PI and aSS, while PT was significantly correlated with PI, aSS, aPT, and body weight. Also, PT was significantly larger in females than in males. Multiple linear regression analysis deduced the following equations: SS=0.404×aSS+0.203×PI+12.463, PT=−0.391×aSS+0.774×PI+1.950×sex (male=0, female=1)−12.971, wherein aSS had the greatest effect for predicting SS among the included factors and PI had the greatest effect for predicting PT. In addition, no significant differences were noted between PT/PI and aPT/PI. Conclusions: As per the results of this study, significant correlations were noted among parameters and predicting models for positional parameters (SS and PT) using anatomical parameters (aSS and aPT) in a healthy population. This novel measurement concept based on the APP has been considered to be useful in estimating natural SS and PT in standing position using the anatomical pelvic parameters in patients with ASD.

Purpose Although the incidence of distal junctional problems (DJPs) following long construct‐based treatment for degenerative lumbar scoliosis (DLS) is lower, affected patients are more likely to require revision surgery when they occur. So the aim of this study is to identify risk factors associated with DJPs to avoid its occurrence by at least 1‐year follow‐up. Methods A total of 182 DLS patients undergoing long instrumented fusion surgery (≥4 levels) between February 2011 and March 2022 were retrospectively analyzed. Patients were placed into the DJP group if a DJP occurred at the final follow‐up; patients without mechanical complications were matched 1:2 according to age, sex and BMI as the control group. Patient characteristics, surgical variables, radiographic parameters, lumbar muscularity and fatty degeneration were analyzed statistically. The statistical differences in the results between the two groups (p values

Objective Pelvic compensation is common in femoroacetabular impingement (FAI) patients to reduce symptoms and increase range of motion. However, little attention was given to the postoperative clinical effect of pelvic compensation. Therefore, this study aims to compare the outcomes between pelvic compensation and normal pelvic position in femoroacetabular impingement (FAI) patients after hip arthroscopy. Methods The retrospective study was conducted from January 2019 to June 2022, recruited consecutive patients who were diagnosed with FAI and received subsequent arthroscopic treatment. All patients completed an X‐ray in the anterior–posterior standing position before and 4 weeks after surgery. Patients with pelvic compensation were compared with those who did not. Functional outcomes included hip disability and osteoarthritis outcome score (HOOS), modified Harris (mHHS) score, and lower‐extremity activity scale (LEAS). Secondary outcomes included the EuroQol Five Dimensions Questionnaire (EQ‐5D) and patient satisfaction. The intraclass correlation coefficient (ICC) was used to analyze interobserver and intraobserver reliability. Results Ninety patients with a mean age of 39.40 years were included in the study. No significant compensation changes were noted within groups after the elimination of impingement. The functional scores showed no significant difference between groups (p(HOOS) = 0.352, p(mHHS) = 0.183, p(LEAS) = 0.865). The EQ‐5D revealed statistically better performance in usual activities in the compensatory group (p = 0.044). There are no significant between‐group differences in patients' satisfaction evaluations. Conclusion As assessed by Patient‐Reported Outcome Measures (PROMs), patients with compensatory pelvic tilt demonstrated similar clinical outcomes without extra adverse events to patients with normal pelvic positioning in short‐term follow‐ups. Furthermore, compensatory pelvic tilt did not significantly enhance the range of motion or functional outcome at short‐term follow‐ups.

Purpose: Sprint kinematics have been linked to hamstring injury and performance. This study aimed to examine if a specific 6-week multimodal intervention, combining lumbopelvic control and unning technique exercises, induced changes in pelvis and lower-limb kinematics at maximal speed and improved sprint performance. Methods: Healthy amateur athletes were assigned to a control or intervention group (IG). A sprint test with 3-dimensional kinematic measurements was performed before (PRE) and after (POST) 6 weeks of training. The IG program included 3 weekly sessions integrating coaching, strength and conditioning, and physical therapy approaches (eg, manual therapy, mobility, lumbopelvic control, strength and sprint "front-side mechanics"-oriented drills). Results: Analyses of variance showed no between-group differences at PRE. At POST, intragroup analyses showed PRE–POST differences for the pelvic (sagittal and frontal planes) and thigh kinematics and improved sprint performance (split times) for the IG only. Specifically, IG showed (1) a lower anterior pelvic tilt during the late swing phase, (2) greater pelvic obliquity on the free-leg side during the early swing phase, (3) higher vertical position of the front-leg knee, (4) an increase in thigh angular velocity and thigh retraction velocity, (5) lower between-knees distance at initial contact, and (6) a shorter ground contact duration. The intergroup analysis revealed disparate effects (possibly to very likely) in the most relevant variables investigated. Conclusion: The 6-week multimodal training program induced clear pelvic and lower-limb kinematic changes during maximal speed sprinting. These alterations may collectively be associated with reduced risk of muscle strain and were concomitant with significant sprint performance improvement. [ABSTRACT FROM AUTHOR]

Background: Low back pain (LBP) is one of the most common conditions in industrialized modern societies. Low back pain is usually nonspecific or mechanical. People with LBP have previously been found to have poor endurance and delayed Gluteus Maximus muscle firing. Anterior pelvic tilt was also believed to cause pelvic girdle discomfort and generalized LBP. Purpose: To evaluate the effectiveness of Gluteus Maximus Activation in correcting anterior pelvic tilt, reducing pain and improving the Functional Outcome among Mechanical Low back pain subjects. Materials and Methods: About 250 participants were selected from Thiraviam Orthopaedic Hospital by using Kinovea software based on inclusion and exclusion criteria. They were divided into 2 groups, Experimental Group (n=125), Control Group (n=125). Both groups were given stretching exercises then Experimental group was given Gluteus Maximus activation exercise with IFT and Control group was given spinal stabilization exercise with IFT. Interventions were given 5 times a week for 6 weeks. Study period : October 2022 to July 2023. Results: Pre-test and post-test values were analyzed and the result suggests that GM Activation Group has significant improvement when compared with Spinal stabilization Group with P<0.0001. Conclusion: According to this study, Gluteus Maximus activation exercises are more effective in correcting anterior pelvic tilt and reducing pain and improving functional outcome among Mechanical Low back pain subjects. [ABSTRACT FROM AUTHOR]

Introduction and hypothesis: Urinary incontinence (UI) is a common public health problem and postural changes may be crucial in women presenting with UI. This study was aimed at evaluating the relationship between low back pain (LBP), pelvic tilt (PT), and lumbar lordosis (LL) in women with and without UI using the DIERS formetric 4D motion imaging system. To date no study has to our knowledge compared postural changes and LBP in women with UI using the DIERS 4D formetric system. Methods: This was a case–control study. We included 33 women with UI and 33 without incontinence. The severity of urogenital symptoms was assessed by the IIQ-7 (Incontinence Impact Score) and UDI-6 (Urogenital Distress Inventory), and disability owing to LBP was evaluated using the Oswestry Disability Index (ODI). Posture and movement assessment, LL angle, thoracic kyphosis, and PT assessment were performed with the DIERS Formetric 4D motion imaging system. Results: The LL angle and pelvic torsion degree were higher in the incontinence group than in the control group (53.9 ± 9.5° vs 48.18 ± 8.3°; p = 0.012, 3.9 ± 4.1 vs 2.03 ± 1.8 mm; p = 0.018 respectively). The LBP visual analog scale value was also significantly higher in the incontinence group (5.09 ± 2.3 vs 1.7 ± 1.8 respectively, p < 0.0001). The LL angle showed a positive correlation with pelvic obliquity, (r = 0.321, p < 0.01) and fleche lombaire (r = 0.472, p < 0.01) and a negative correlation with lumbar range of motion measurements. Pelvic obliquity correlated positively with pelvic torsion (r = 0.649, p < 0.01), LBP (r = 0.369, p < 0.01), and fleche lombaire (r = 0.269, p < 0.01). Conclusions: Women with UI were more likely to have lumbopelvic sagittal alignment changes and a higher visual analog scale for LBP. These findings show the need for assessment of lumbopelvic posture in women with UI. [ABSTRACT FROM AUTHOR]

PURPOSE OF THE STUDY Spine stabilization surgery is nowadays one of the most common spinal surgical procedures. Spinopelvic alignment is considered to be an important factor impacting the patients’ preoperative difficulties as well as the outcome of surgery. In our study, the outcomes of stabilization surgeries in patients with lumbar spine disorders were evaluated – especially in those with stenosis and spondylolisthesis, in whom the importance of sagittal parameters were assessed with respect to the patients’ clinical outcomes and difficulties. MATERIAL AND METHODS The study included 50 patients with lumbar spine disorders who had undergone a spine stabilization surgery for a degenerative disease – lumbar spinal stenosis, spondylolisthesis between 2015 and 2017. Spino-pelvic radiological parameters and clinical parameters were evaluated using the nonparametric Kruskal-Wallis, Mann-Whitney, and Wilcoxon tests. RESULTS In 38 of 50 patients, who at the end of the follow-up period did not have the PI-LL (pelvic incidence-lumbar lordosis) mismatch, i.e. PI-LL was ≤10°, a statistically significant difference in pelvic tilt (p=0.049) and sagittal vertical axis (p<0.001) was reported, which was not the case in the remaining patients of the study population. Claudication and OSWESTRY (ODI) showed no statistically significant difference. We have also compared the differences in the number of fused vertebrae and type of stabilization. A significant change was seen in the claudication parameter at 12 and 24 months after surgery (p=0.007, p=0.005), with better outcomes achieved by 360° lumbar fusion compared to posterior lumbar fusion. The improvement of VAS and ODI scores in both the groups over time (from 6.1 to 3.6 or from 6.3 to 3.5 in VAS and from 62 to 32, or from 62 to 30 in ODI) was also statistically significant (p<0.001 in both groups), while when comparing the groups against each other it was statistically insignificant. DISCUSSION The authors confirmed significant improvement in the studied clinical parameters in all groups of patients (VAS, ODI, claudication), which is consistent with the results of recently published papers. The authors also established the correlation between different radiological parameters in the studied groups. The results do not confirm the importance of the length or type of instrumentation for the clinical outcomes. This is consistent with the findings of other published manuscripts. The authors failed to confirm a significant change in clinical parameters in dependence on the matching relationship between the pelvic incidence and lumbar lordosis. CONCLUSIONS Proper spinopelvic balance in patients after spinal surgery is a very important indicator of postoperative development and condition, but our cohort showed no statistically significant difference in the clinical outcomes of patients whose postoperative sagittal parameters were unsatisfactory. [ABSTRACT FROM AUTHOR]

Purpose: Although the incidence of distal junctional problems (DJPs) following long construct‐based treatment for degenerative lumbar scoliosis (DLS) is lower, affected patients are more likely to require revision surgery when they occur. So the aim of this study is to identify risk factors associated with DJPs to avoid its occurrence by at least 1‐year follow‐up. Methods: A total of 182 DLS patients undergoing long instrumented fusion surgery (≥4 levels) between February 2011 and March 2022 were retrospectively analyzed. Patients were placed into the DJP group if a DJP occurred at the final follow‐up; patients without mechanical complications were matched 1:2 according to age, sex and BMI as the control group. Patient characteristics, surgical variables, radiographic parameters, lumbar muscularity and fatty degeneration were analyzed statistically. The statistical differences in the results between the two groups (p values <0.05) and other variables selected by experts were entered into a multivariate logistic regression model, and the forwards likelihood ratio method was used to analyze the independent risk factors for DJPs. Results: Twenty‐four (13.2%) patients suffered a DJP in the postoperative period and the reoperation rate was 8.8%. On univariate analysis, the lowest instrumented vertebra (LIV) CT value (p = 0.042); instrumented levels (p = 0.030); preoperative coronal vertical axis (CVA) (p = 0.046), thoracolumbar kyphosis (TLK) (p = 0.006), L4‐S1 lordosis (p = 0.013), sacral slop (SS) (p = 0.030), pelvic tilt (PT) classification (p = 0.004), and sagittal vertical axis (SVA) (p = 0.021); TLK correction (p = 0.049); post‐operative CVA (p = 0.029); Overall, There was no significant difference in the paraspinal muscle parameters between the two groups. On multivariate analysis, instrumented levels (OR = 1.595; p = 0.035), preoperative SVA (OR = 1.016; p = 0.022) and preoperative PT (OR = 0.873; p = 0.001) were identified as significant independent risk factors for DJP. Conclusion: Longer instrumented levels, a greater preoperative SVA and a smaller PT were found to be strongly associated with the presence of DJPs in patients treated for DLS. The degeneration of the paraspinal muscles may not be related to the occurrence of DJPs. For DLS patients, the occurrence of DJP can be reduced by selecting reasonable fusion segments and evaluating the patient's sagittal balance and spino‐pelvic parameters before operation. [ABSTRACT FROM AUTHOR]

Background: Femoroacetabular impingement is one possible cause for groin pain and can lead to long periods of absence for football players. In cam impingement, the end-grade position of the leg at kicking makes the hip particularly prone to faulty contact between the acetabulum and the femoral head. Studies suggest that the resting position of the pelvis in the sagittal plane may have an important role in the biomechanics of movement in the presence of cam impingement. Methods: A 19-year-old male competitive footballer complained of sudden groin pain during a period of low athletic load. Biomechanical tests (3D posture and isometric strength analyses) showed that unbalanced individual strength training had resulted in an increased forward tilt of the pelvis. At the same time, cam impingement was confirmed radiologically, which obviously contributed to the sudden onset of the symptoms. The kicking technique of the athlete showed increased hip and trunk flexion, which also indicated a muscular imbalance. Targeted strength and stretching exercises three times a week improved the pelvic position in terms of reduced anteversion. At the same time, the patient performed strength exercises to improve his kicking technique. Results: After 8 weeks, improvements in his pelvic position and global posture and increased muscle strength could be verified. At the same time, the athlete was free of complaints again. Conclusions: When groin pain occurs in football players with cam impingement, special attention should be paid to the resting position of the pelvis in the sagittal plane. Correcting increased pelvic anteversion can prevent unfavourable end-grade collisions of the acetabulum and femoral head during kicking with strong hip flexion and adduction. Possible changes in the pelvic position due to adverse individual strength training performed by young athletes should always be kept in mind. [ABSTRACT FROM AUTHOR]

Spino-pelvic orientation may affect dislocation risk following total hip arthroplasty (THA). It can be measured on lateral lumbo-pelvic radiographs. The sacro-femoro-pubic (SFP) angle, measured on an antero-posterior (AP) pelvis radiograph, is a reliable proxy for pelvic tilt, a measurement of spino-pelvic orientation measured on a lateral lumbo-pelvic radiograph. The purpose of this study was to investigate the relationship between SFP angle and dislocation following THA. An Institutional Review Board-approved retrospective case-control study was conducted at a single academic center. We matched 71 dislocators (cases) to 71 nondislocators (controls) following THA performed by 1 of 10 surgeons between September 2001 and December 2010. Two authors (readers) independently calculated SFP angle from single preoperative AP pelvis radiographs. Readers were blinded to cases and controls. Conditional logistic regressions were used to identify factors differentiating cases and controls. The data did not show a clinically relevant or statistically significant difference in SFP angles after adjusting for gender, American Society of Anesthesiologists classification, prosthetic head size, age at time of THA, measurement laterality, and surgeon. We did not find an association between preoperative SFP angle and dislocation following THA in our cohort. Based on our data, SFP angle as measured on a single AP pelvis radiograph should not be used to assess dislocation risk prior to THA. [ABSTRACT FROM AUTHOR]

As the pelvis is a dynamic structure, the quantification of pelvic tilt (PT) should be done in different hip positions prior to total hip arthroplasty (THA). We sought to investigate functional PT in young female patients undergoing THA and explore the correlation of PT with the extent of acetabular dysplasia. Additionally, we aimed to define the PS-SI (pubic symphysis-sacroiliac joint) index as a PT quantifier on AP pelvis X-ray. Pre-THA female patients under the age of 50 years (n = 678) were investigated. Functional PT in 3 positions (supine, standing, and sitting) were measured. Hip parameters including lateral center-edge angle (LCEA), Tönnis angle, head extrusion index (HEI), and femoro-epiphyseal acetabular roof (FEAR) index were correlated to PT values. The PS-SI/SI-SH (sacroiliac joint-sacral height) ratio was also correlated to PT. From the 678 patients, 80% were classified as having acetabular dysplasia. Among these patients, 50.6% were bilaterally dysplastic. The mean functional PT of the entire patient group was 7.4°, 4.1°, and −1.3° in the supine, standing and seated positions. The mean functional PT of the dysplastic group was 7.4°, 4.0°, and −1.2° in the supine, standing and seated positions. The PS-SI/SI-SH ratio was found to be correlated to PT. Most of the pre-THA patients had acetabular dysplasia and exhibited anterior PT in the supine and standing positions, most pronounced in the standing position. PT values were comparable between the dysplastic and non-dysplastic group without change with worsening dysplasia. PS-SI/SI-SH ratio can be used to easily characterize PT. [ABSTRACT FROM AUTHOR]

Objective: Pelvic compensation is common in femoroacetabular impingement (FAI) patients to reduce symptoms and increase range of motion. However, little attention was given to the postoperative clinical effect of pelvic compensation. Therefore, this study aims to compare the outcomes between pelvic compensation and normal pelvic position in femoroacetabular impingement (FAI) patients after hip arthroscopy. Methods: The retrospective study was conducted from January 2019 to June 2022, recruited consecutive patients who were diagnosed with FAI and received subsequent arthroscopic treatment. All patients completed an X‐ray in the anterior–posterior standing position before and 4 weeks after surgery. Patients with pelvic compensation were compared with those who did not. Functional outcomes included hip disability and osteoarthritis outcome score (HOOS), modified Harris (mHHS) score, and lower‐extremity activity scale (LEAS). Secondary outcomes included the EuroQol Five Dimensions Questionnaire (EQ‐5D) and patient satisfaction. The intraclass correlation coefficient (ICC) was used to analyze interobserver and intraobserver reliability. Results: Ninety patients with a mean age of 39.40 years were included in the study. No significant compensation changes were noted within groups after the elimination of impingement. The functional scores showed no significant difference between groups (p(HOOS) = 0.352, p(mHHS) = 0.183, p(LEAS) = 0.865). The EQ‐5D revealed statistically better performance in usual activities in the compensatory group (p = 0.044). There are no significant between‐group differences in patients' satisfaction evaluations. Conclusion: As assessed by Patient‐Reported Outcome Measures (PROMs), patients with compensatory pelvic tilt demonstrated similar clinical outcomes without extra adverse events to patients with normal pelvic positioning in short‐term follow‐ups. Furthermore, compensatory pelvic tilt did not significantly enhance the range of motion or functional outcome at short‐term follow‐ups. [ABSTRACT FROM AUTHOR]

Introduction: The relationship between anterior pelvic tilt and overall sagittal alignment has been well-described previously. However, the relationship between pelvic tilt, frontal, and axial leg alignment remains unclear. The aim of the study was to analyze the relationship between pelvic tilt and frontal and axial leg alignment in healthy subjects.Material and Methods: Thirty healthy subjects (60 legs) without prior surgery underwent standing biplanar long leg radiograph. Pelvic parameters (pelvic tilt, pelvic incidence, sacral slope), hip-knee-ankle angle (HKA), femoral antetorsion and tibial torsion were measured using SterEOS (EOS Imaging) software. EOS was acquired with the feet directing straight anteriorly, which corresponds to a neutral foot progression angle (FPA). The influence of HKA, femoral antetorsion, tibial torsion and gender on pelvic tilt was analyzed in a univariate correlation and multiple regression model.Results: Sixteen female subjects and 14 male subjects with a mean age of 27.1 years ± 10 (range 20-67) were included. HKA, femoral antetorsion, and tibial torsion correlated with anterior pelvic tilt in univariate analysis (all p < 0.05). Anterior pelvic tilt increased 1.1° (95% CI: 0.7 to 1.5) per 1° of knee valgus (p < 0.001) and 0.5° (95% CI: 0.3 to 0.7) per 1° of external tibial torsion (p < 0.001). Overall, linear regression model fit explained 39% of variance in pelvic tilt by the HKA, femoral antetorsion and tibial torsion (R2 = 0.385; p < 0.001).Conclusion: Valgus alignment and increasing tibial torsion demonstrated a weak correlation with an increase in anterior pelvic tilt in healthy subjects when placing their feet anteriorly. The relationship between frontal, axial leg alignment and pelvic tilt needs to be considered in patients with multiple joint disorders at the hip, knee and spine. Alteration of the frontal, or rotational profile after realignment surgery or by implant positioning might influence the pelvic tilt when the FPA is kept constant. [ABSTRACT FROM AUTHOR]

Background: Instability is a known complication following total hip arthroplasty (THA) and is influenced by spinopelvic alignment. Radiographic markers have been investigated to optimize the acetabular cup position. This study evaluated if the empty ischial fossa (EIF) sign and the position of the trans-teardrop line were predictive of postoperative instability. Methods: All patients who underwent THA from 2011 to 2018 at a single institution were retrospectively reviewed. Pelvic tilt was measured using a trans-teardrop line compared to the superior aspect of the pubic symphysis on standing anteroposterior pelvis radiographs. Postoperative dislocations were identified through chart review and radiographic review. The EIF sign was determined by the presence of uncovered bone below the posterior inferior edge of the acetabular component at the level of the native ischium and posterior wall on standing postoperative anteroposterior radiographs. Results: One thousand seven hundred fifty patients (952 anterior approach and 798 posterior approach) were included. The EIF sign was present in 458 patients (26.2%) and associated with an increased dislocation rate (3.9% vs 0.9%, P < .0001). Patients with spondylosis/instrumented fusion, and positive EIF sign had a dislocation risk of 5.1% vs 1.3% (P = .001). A postoperative outlet pelvis was not significant for increased dislocation risk (odds ratio 2.16, P = .058). Patients with combined spondylosis/fusion, posterior approach, outlet pelvis, and EIF sign had a dislocation rate of 14.5%. Conclusions: The EIF sign was an independent risk factor for postoperative instability and may represent failure to account for pelvic tilt. Avoidance of the EIF sign during cup positioning may help reduce dislocations following THA.