Femoral Anteversion Research Articles

Combined Anteversion in Healthy Hips: Should there be a single implant alignment target in total hip arthroplasty?

The ideal anteversion at which the acetabular and femoral components for a total hip arthroplasty (THA) should be implanted is still a subject of debate. One alignment philosophy being explored is restoration of individual constitutional femoral and acetabular anteversion. This study aimed to measure combined anteversion in a healthy hip population and understand the expected phenotypes and ranges for constitutional hip alignment. Computed tomography (CT) scans of 338 healthy hips were analysed using an advanced modelling and analysis software that automatically maps landmarks consistently across all scans. Four distinct methods for measuring the acetabular and femoral versions were employed, each derived from different landmark placements. Acetabular and femoral versions were classified as either normal (10° - 20°), increased (> 20°), or decreased (<10°), resulting in nine potential hip phenotypes, and the prevalence of each in the healthy population was determined. Femoral and acetabular version angles varied depending on the number of points used to measure them. There was wide variability in acetabular and femoral anteversion angles, ranging from 6° to 26° acetabular anteversion, and from 5° retroversion to 32° femoral anteversion. Only 29% of hips were found to have constitutional combined anteversion between 20° and 40°, withacetabular version between 10° - 20° and femoral version between 10° - 20°. There is increasing interest in individualised implant alignment for THA, since studies have shown the Lewinnek "safe zone" does not guarantee hip stability. The results found in this study suggest that a single target for implant alignment may not be optimal for recreating a patient's constitutional hip alignment. Further research should consider how changes in combined anteversion during THA implant placement can impact patient outcomes.

Lumbopelvic hyperlordosis is linked to higher femoral head coverage, lower femoral anteversion and younger age at periacetabular osteotomy.

The dynamic alignment of the lumbar spine, pelvis and femur is increasingly studied in hip preservation surgery. However, the interaction between lumbopelvic alignment, acetabular and femoral morphology and its influence on patients' preoperative symptom burden remains poorly understood. The aim of this study was to evaluate whether lumbopelvic malalignment affects osseous hip morphology and exacerbates preoperative patient-reported joint functionality in patients undergoing periacetabular osteotomy (PAO). One hundred thirteen patients were prospectively enroled in this single-centre study. Sagittal lumbopelvic radiographs were used to divide the patients in accordance with their lumbopelvic alignment (pelvic incidence [PI]-lumbar lordosis [LL] mismatch) into a balanced (PI-LL: 10° and 10°/n = 60) and unbalanced alignment (PI-LL: <10° and >10°/n = 53) group. Intergroup analyses were performed for acetabular and femoral morphology as well as various patient-reported outcome measures (PROMs) scores (modified Harris-Hip, Hip Osteoarthritis Outcome, International Hip Outcome tool-12 and University of California Los Angeles activity scale). Patients with concomitant unbalanced lumbopelvic alignment due to hyperlordosis showed higher femoral head coverage and lower femoral anteversion (lateral centre-edge angle 20.2° vs. 15.8°, p = 0.012/anterior wall index 0.47 vs. 0.36, p = 0.001/acetabular inclination 10.2° vs. 13.6°, p = 0.008/Femoral anteversion 21.3° vs. 28.2°, p = 0.041). Furthermore, these patients were significantly younger at the time of PAO (28.7 vs. 32.4 years, p = 0.020), even when there were no intergroup differences in all analyzed PROMs. Concomitant lumbopelvic deformity affecting the hip joint morphology could aggravate clinical symptoms leading to earlier presentation in patients undergoing PAO. Thus, the lumbopelvic balance needs to be carefully evaluated in clinical decision-making in PAO patients and future research should focus on long-term outcomes of patients with concomitant unbalanced lumbopelvic alignment. Level III, prognostic study.

Patients with jumping sign exhibit rotational and bony structural abnormalities consistent with high-grade J-sign in recurrent patellar dislocation.

To propose a new sign of patellar maltracking in recurrent patellar dislocation (RPD) and compare the differences in lower limb rotational and bony structural abnormalities among the different signs. A retrospective study included 279 patients (mean age: 22 years; female: 81%) who underwent primary surgery for RPD over the past 4 years was performed. The patients were grouped based on the characteristics of patellar tracking: low-, moderate- and high-grade J-sign. Patients were further divided into 'jumping' and 'gliding' subgroups based on whether the patella exhibited a 'jumping' sign during flexion-extension motion. All patients received bilateral standard hip-knee-ankle CT scans. The rotational and bony structural parameters of affected knees were measured, and the differences in these variables among the groups were described and analyzed. Reliability analysis was performed to test the consistency of J-sign grading and measurements. There were 92, 100 and 87 patients in the low-, moderate- and high-grade J-sign, respectively. The overall incidence of the jumping sign is 37%. The incidence of the 'Jumping sign' in the high-grade J-sign was significantly higher than in the other two groups (82% vs. 32% vs. 0, p < 0.001). Compared to those with the gliding sign, patients with the jumping sign have higher proportions of increased femoral anteversion (40.8% vs. 24.4%, p = 0.004), excessive knee torsion (61.2% vs. 15.3%, p < 0.001), trochlear dysplasia (95.1% vs. 69.3%, p < 0.001), pronounced supratrochlear spur (73.1% vs. 32.3%, p < 0.001), increased tibial tuberosity-trochlear groove distance (68% vs. 43.3%, p < 0.001), flatter lateral trochlear inclination (81.3% vs. 27.5%, p < 0.001) and excessive sulcus angle (68.7% vs. 35.3%, p = 0.003). No significant morphological differences were found in various bony structural parameters between knees with jumping sign and high-grade J-sign (all p > 0.05). The inter-observer reliability kappa values were 0.65 for the quadrant classification and 0.83 for the new patellar sign. In RPD patients, the rotational and bony structural abnormalities in the jumping sign are highly consistent with the high-grade J sign. This finding may assist the surgeon and their patients in making informed decisions about further imaging tests and osteotomy procedures in the treatment of RPD. Level IV, cross-sectional study.

Surrogate-based positioning optimization of hip prostheses for minimal stress shielding

The stress shielding phenomenon causes undesirable changes in stress distribution in the bones in which implants are implanted. This phenomenon leads to a gradual decrease in bone density in the vicinity of the implant and ultimately loosening. To improve the endurance of the prosthesis and postpone the revision surgery the prosthesis should be designed and positioned in such a way that the post-implant stress distribution within the bones is as close to the natural distribution as possible.We formulate the problem of achieving a near-normal stress distribution as a constrained optimization problem in which the difference between pre- and post-implant stress distributions constitutes the loss function and five positional and dimensional parameters, including Femoral Anteversion, Neck Shaft Angle, Femoral Head Offset, Cup Version, and Cup Inclination comprise the set of design variables. Finite Elements (FE) analysis is used to obtain the stress distribution in bones before and after the implantation. To create a FE model, first a three-dimensional model of the patient's hip is created using CT images. The model is then subjected to the loads obtained from the patient's gait analysis, and the Stress Shielding Index (SSI) is calculated at critical points of the bones before and after the implantation. The difference between pre- and post-implant SSI values defines the cost function. To reduce the computational cost of numerous cost function evaluations a surrogate model (a 5 × 1 MLP neural network) is employed to predict the value of the cost function. Design Of Experiments (DOE) is used to sample the hyperspace of the design variables and generate training, test and validation data. The optimization problem is solved using Genetic Algorithms and the results are compared with with the results of the best set of initial samples.Results from the proposed approach show a significant reduction in the difference between pre- and post-implant stress distributions and a 12% reduction in the Stress Shielding Index.

Clinical Study on the Effects of Total Hip Arthroplasty Assisted by Virtual Planning Combined With Intraoperative Navigation Templates.

Although total hip arthroplasty (THA) effectively alleviates pain and restores joint function in the end-stage hip disease, challenges remain in achieving precise osteotomy and minimizing subjective dependency on prosthesis positioning. This study aims to evaluate the efficacy and safety of preoperative virtual planning and navigation templates compared to conventional techniques, providing new methods to enhance the precision and personalization of THA. During the period from 2022 to 2023, we conducted a retrospective case-control study on 74 patients who underwent THA surgery at our hospital, based on the inclusion and exclusion criteria. The study included 42 patients in the traditional method group, who underwent preoperative planning and surgical procedures according to traditional methods; and 32 patients in the digital assistance group, who used computer-assisted virtual preoperative planning and three-dimensional printed personalized navigation templates to assist in the surgery. The main parameters of the two groups were compared, including surgical time, blood loss, postoperative femoral anteversion, neck-shaft angle, anatomical-mechanical femoral axis angle (aMFA), leg length discrepancy (LLD), and the angle of hip prosthesis placement. The Harris hip score was recorded both preoperatively and at the final follow-up to assess the accuracy of the prosthesis placement and the prognosis of the patients. There were no significant differences in femoral anteversion, neck-shaft angle, aMFA, or LLD between the two groups. However, the digital group showed smaller deviations between the planned and actual acetabular prosthesis angles compared to the conventional group, with shorter operative times and reduced blood loss. Follow-up Harris hip scores were significantly higher in the digital group (p < 0.05). Digital technology enhances the accuracy and reproducibility of prosthesis placement in THA, reduces operative time and blood loss, and shows a promising potential for broader application.

Improving Femoral Torsion Evaluation in Infants Through Analysis of Variability and Reliability in 2D and 3D Imaging Measurements of the Femoral Neck Axis

Abstract The femoral neck axis serves as a critical parameter in evaluating hip joint health, particularly in the pediatric population. Commonly used metrics for evaluating femoral torsion, such as the femoral neck-shaft and femoral anteversion angles, rely heavily on precise definitions of the position and orientation of the femoral neck axis. Current measurement methods employing radiographs and performing two-dimensional (2D) measurements on computed tomography (CT) scans are susceptible to errors due to their reliance on reader experience and the inherent limitations in 2D measurements. We hypothesized that utilizing volumetric data would mitigate these errors and enable more accurate and reproducible measurements of the femoral neck axis using the femoral anteversion and femoral neck-shaft angles. To test this hypothesis, we analyzed a historical collection of post-mortem infant femoral and pelvic bones (28 hips) aged 0 to 6.5 months, with an average estimated age of 4.68 months ± 1.80 months. Our findings revealed an average neck-shaft angle of 128.00 ± 4.92± and femoral anteversion angle of 35.56 ± 11.68± across all femurs, consistent with literature values. These measurements obtained from volumetric image data were found to be repeatable and reliable compared to conventional methods. Our study suggests that the proposed methodology offers a standardized approach for obtaining repeatable and reproducible measurements, thus potentially enhancing diagnostic accuracy and clinical decision-making in assessing hip developmental conditions in pediatric patients.

Assessing Femoral Anteversion in Patients With Bilateral Recurrent Patellar Dislocations.

After first-time lateral patellar dislocation, 44% to 70% of patients sustain redislocations. Increased femoral anteversion (FA) is considered to result in increased lateralizing forces on the patella, which might predispose one to patellar instability. When recurrent patellar dislocations (RPDs) are bilateral, it is unclear if the FA is even more increased. Patients with bilateral RPD would have greater FA than patients with unilateral RPD. Case-control study; Level of evidence, 3. A total of 52 skeletally mature patients with RPD and a clinical suspicion of rotational malalignment underwent rotational computed tomography or magnetic resonance imaging. The uni- or bilaterality of the RPD was determined. A control group comprising 54 adult patients with trauma underwent computed tomography of both lower extremities as part of a multitrauma protocol. The FA values of both lower extremities were evaluated separately. In total, 20 of 52 (38.5%) patients in the study group had a history of unilateral RPD and 32 of 52 (61.5%) patients had a bilateral RPD diagnosis. The mean FA of the asymptomatic limb in unilaterally symptomatic patients was 18.0° (SD, 11.2°; range, 0.5°-40.0°; median, 16.5°). In the symptomatic limb, the mean FA was 19.2° (SD, 9.1°; range, 2.0°-33.0°; median, 19.0°) (mean difference, 1.2°; 95% CI -1.3° to 3.8°). In bilaterally symptomatic patients, the mean FA on the right side was 23.2°, and 22.5° on the left. The mean differences between the symptomatic limbs in the unilateral RPD group and the right or left limbs in the bilateral RPD group were 4.0° (P = .263) and 3.3° (P = .326), respectively. In the control group without RPD, the mean FA was 12.5° (SD, 8.5°; range, 0.8°-33.0°; median, 10.9°). The mean difference between right limbs of the patients with bilateral RPD and right limbs of controls was 10.8° (P = .001). Patients with bilateral RPD have bilaterally greater FA than patients without a history of RPD. Patients with unilateral RPD have greater FA on both sides compared with the control group without a history of lateral patellar dislocation. No statistically significant difference of FA can be seen between patients with bilateral or unilateral RPD.

Analysis of posterior hip joint impingement about developmental dysplasia of the hip after total hip arthroplasty.

Total hip arthroplasty is the preferred treatment for advanced hip osteoarthritis, yet complications like hip dislocation (0.2%-10%) persist due to factors such as implant design, positioning, surgical technique, and patient-specific conditions. Impingement between prosthetic components or the acetabulum and proximal femur is a primary cause of instability. A retrospective analysis of 120 patients (130 hips) undergoing total hip arthroplasty at XX Hospital (2011-2023) categorized patients by lateral center-edge angle: developmental dysplasia of the hip, borderline developmental dysplasia of the hip, and normal hip. ct imaging facilitated virtual 3D bone models for motion analysis, excluding cases with prior hip surgery or spinal fusion. Statistical analyses utilized the Mann-Whitney U test and one-way ANOVA. The developmental dysplasia of the hip group showed the highest posterior impingement frequency, significantly affecting range of motion in flexion, adduction, and external rotation compared to borderline developmental dysplasia of the hip and normal hip groups. Variations in femoral neck anteversion, lesser trochanter version, and ischiofemoral space were notable. Posterior impingement commonly occurred between the lesser trochanter and ischial tuberosity. Posterior bony impingement emerged as a predominant factor reducing range of motion and increasing dislocation risk, particularly in developmental dysplasia of the hip patients, challenging the conventional "safe zone" for implant positioning. Personalized surgical strategies tailored to individual bone morphology are crucial for enhancing total hip arthroplasty outcomes and minimizing complications, although limitations include the exclusion of soft tissue influences and focusing solely on range of motion until impingement occurs.

The Impact of Rotational Malalignment Following Intramedullary Nailing for Intertrochanteric Fractures on Patients' Functional Outcomes: A Prospective Study.

Background & Aims: Rotational malalignment after intramedullary nailing of intertrochanteric fractures is a relatively common complication that may have a crucial impact on both functional outcome and a fracture's healing properties, ultimately affecting the patient's postoperative morbidity and mortality. Methods: 74 patients treated with intramedullary nailing due to an intertrochanteric fracture underwent a postoperative computed tomography (CT) scan of the hips and knees. The femoral anteversion difference (D angle) between the operated and healthy hip was calculated using the technique described by Jeanmart et al. The patients were divided into two groups according to their D angle values: a D angle less than 15° was considered an acceptable rotational alignment (group A), while a D angle equal to or more than 15° was considered a rotational deformity (group B). Postoperatively, the functional level of each patient was evaluated at the 6-month and 1-year follow-up visits and compared to the pre-fracture status using the modified Harris hip score (mHHS). Also, fracture union, other postoperative complications, and patient mortality were noted. Results: The mean femoral anteversion difference was 12.3° with a standard deviation of 10.3°. Of the 74 patients, 51 (68.9%) were assigned to group A and 23 (31.1%) to group B. At the 6-month postoperative follow-up, 67 (90.5%) patients had survived and 7 (9.5%) were deceased, with our statistical analysis indicating a linear trend (p-value = 0.048) between the presence of rotational malalignment and 6-month mortality. At the 1-year postoperative follow-up, 63 (85.1%) patients survived and 11 (14.9%) were deceased, with the statistical analysis indicating a significant relationship (p-value = 0.031) between the presence of rotational malalignment and the 1-year mortality. Regarding the functional outcome six months after the operation, the difference between the pre-fracture and the postoperative mHHS was 8.7/100 with a standard deviation of 6.1 for the 49 patients in group A and 14.5/100 with a standard deviation of 12.4 for the 18 patients in group B, with the statistical analysis indicating a significant difference (t = -2.536, significance < 0.05) in the functional level between the two groups. As for the functional outcome one year after the operation, the difference between the pre-fracture and the postoperative mHHS was 4.9/100 with a standard deviation of 7.8 for the 47 patients in group A and 8.3/100 with a standard deviation of 13 for the 16 patients in group B, with the statistical analysis indicating no significant difference (t = -1.266, significance > 0.05) in the functional level between the two groups. The only postoperative complication noted was fracture non-union, presenting in two patients (3%), with the statistical analysis indicating no significant relationship (p-value = 0.698) between this complication and the presence of rotational malalignment. Conclusions: In this study, rotational malalignment after intertrochanteric fracture intramedullary nailing presents in 31.1% of cases. The correlation between this malalignment and functional outcomes shows a decline in patients' functional abilities during the first six postoperative months, a condition that improves over time, with most patients returning to their preoperative functional status one year after the operation. Furthermore, our results indicate a possible relationship between rotational malalignment and mortality within one year. Future research should focus on creating a more detailed, functional evaluation system for the elderly and applying it to a larger sample to confirm these findings.

Factors associated with mechanical complications following primary total hip arthroplasty through a modified direct anterior approach using custom stems.

To determine the rate and risk factors of mechanical complications (MCs) within two years following total hip arthroplasty (THA) through direct anterior approach (DAA) using custom stems, and to compare findings to other surgical approaches in the literature. The study included a consecutive series of 479 patients (529 hips) that had undergone primary THA through the DAA using uncemented custom stems between 02/2014 and 04/2017. There were 301 men and 228 women, with a mean age of 55.9 ± 11.6, and a mean body mass index (BMI) of 25.8 ± 4.3kg/m2. All patients were contacted by phone at a minimum follow-up of two years, and those who reported complications were prescribed radiographic imaging and asked to attend clinical assessment. MCs were defined as periprosthetic fracture, aseptic loosening, dislocations, prosthesis failure, prosthesis malposition, or subsidence. At two years follow-up, the rate of MCs was 3.2% (17 hips).The MCs comprised four femoral fractures, three aseptic stem loosening, three cup malpositions, three subsidences, two acetabular fractures, one stem malposition, and one dislocation. Ten hips (1.9%) required revision due to MCs. Compared to patients with no MCs, patients with MCs had significantly greater native femoral anteversion (16.7 ± 7.5º vs. 21.1 ± 9.7º, p = 0.042), more Charnley class C (13% vs. 41%, p = 0.008), fewer diameter 36mm heads (45% vs. 18%, p = 0.044), and performed less intense physical activity (49% vs. 12%, p = 0.006) and sports (66% vs. 35%, p = 0.048). Multivariable analyses suggested that MCs were associated with greater native femoral anteversion (Odds Ratio [OR] = 1.08, p = 0.020) and Charnley class C (OR = 3.47,p = 0.027), but were inversely associated with intense physical activity (OR = 0.19, p = 0.047). The rate of MCs within 2 years following THA through DAA using custom stems was 3.2% and the rate of revision due to MCs was 1.9%, which is within the range reported in the literature on other surgical approaches for THA. Furthermore, the presence of MCs was associated with greater native femoral anteversion and Charnley class C, but was inversely associated with intense physical activity.

Predicting two-year return-to-sport failure after medial patellofemoral ligament reconstruction in patellar dislocation patients with bone abnormalities.

To develop a comprehensive and validated personalized scoring system based on anatomical characteristics to predict the probability of failure to return to sport after medial patellofemoral ligament reconstruction in patients with patellar dislocation. 312 patients with medial patellofemoral ligament reconstruction in our hospital from 2013 to 2023 were included. Demographic and anatomical characteristics were collected retrospectively. A backward stepwise approach was used to identify independent predictors, and a nomogram was constructed to predict the probability of recurrence. The predictive performance was evaluated by receiver operating characteristic curves, calibration diagram and decision curve analysis. Multivariate analysis showed that increased tibial tubercle-trochlear groove (TT-TG) distance, trochlear dysplasia, increased femoral anteversion angle, and patellar alta were independent risk factors for failure of return to sport after medial patellofemoral ligament reconstruction. Validation of this column graph in the training cohort and validation cohort showed strong predictive power, with areas under the curve of 0.850 and 0.844, respectively. The nomogram has good calibration and good clinical practicability. The study developed a personalized predictive nomogram with 4 predictors (increased TT-TG distance, trochlear dysplasia, increased femoral anteversion angle, and patellar alta) that allowed surgeons to stratify the risk of failure to return to sport after medial patellofemoral ligament reconstruction and recommend skeletal surgery for patients with these factors. Level III.

Body Mass Index is Related to Femoral Anteversion, Hip Rotation During Gait, and Passive Hip Range of Motion in Children and Adolescents.

Overweight and obesity are major global health issues, often linked to orthopaedic problems, skeletal malalignments, and altered gait biomechanics. However, skeletal and biomechanical adaptions in the transverse plane remain underexplored. Therefore, this study aimed to investigate the relationship between body mass index (BMI) and variables describing lower extremity torsional profiles, hip rotation mobility, and transverse plane gait characteristics in children and adolescents. Acetabular and femoral anteversion, tibial torsion (measured through computed tomography), hip and knee rotation, and foot progression angles during the stance phase of gait (measured by 3D gait analysis), as well as passive hip rotation range of motion (evaluated as the midpoint of hip rotation in clinical examination), were retrospectively analyzed in 122 children and adolescents. Correlations between all variables and logit-transformed BMI percentiles were calculated. Moderate correlations were found between BMI percentile and hip rotation during the stance phase (r=-0.68, P<0.001), the passive midpoint of hip rotation (r=-0.51, P<0.001), and femoral anteversion (r=-0.50, P<0.001). Small correlations were observed for acetabular anteversion (r=-0.36, P<0.001), knee rotation during stance phase (r=0.34, P<0.001), and foot progression angle during stance phase (r=-0.31, P<0.001). Tibial torsion showed a nonsignificant negligible relationship with BMI percentile (r=-0.26, P=0.004). BMI percentile was positively correlated with external hip rotation during the stance phase of gait and passive external hip rotation, and negatively correlated with femoral anteversion. These findings suggest abnormal body weight is associated with static and dynamic biomechanical alterations. Therefore, weight management should be considered in orthopaedic assessments and treatment planning for children and adolescents.

Measurement Method of Femoral Anteversion During Surgery for Trochanteric Fractures.

The acceptable range of bilateral differences in the femoral rotation is ≤15°, as a difference in femoral rotation over 15° may cause functional disturbance. However,femoral trochanteric fractures do not have clear indicators of rotation during surgery. This study aimed to verify the accuracy of this novel method for measuring femoral anteversion during trochanteric fracture surgery. From August 2022 to August 2024, this study prospectively included patients with femoral trochanteric fractures treated using a cephalo-medullary nail with a lag-screw neck-shaft angle of 125°. During surgery, direct intraoperative anteversion (DIAV) was measured using the hip post axis in the lateral hip image based on a tabletop plane parallel to the floor. DIAV was then converted to corrected intraoperative anteversion (CIAV) using a quick chart derived from a graph of the axial projection. The accuracy was analyzed by comparing CIAV with computed tomography anteversion (CTAV) measurements obtained after surgery. One hundred patients (25 male, 75 female) with a mean age of 86.7 years (range: 67-104 years) were included in this study. According to the Orthopaedic Trauma Association classification, there were 66 patients classified as A1, 23 as A2, and 11 as A3. The mean DIAV and CIAV were 8.2°±8.2° and 9.6°±9.7°, respectively, while the mean CTAV was 10.3°±10.4°. The median difference between CIAV and CTAV was 3° (range: 0°-9°), with 84 patients exhibiting differences of ≤5°. No significant differences were found between CIAV and CTAV (p = 0.054), whereas DIAV was significantly lower than CTAV (p < 0.001). CIAV and CTAV were strongly correlated (r = 0.936, p < 0.001). The Bland-Altman plot between CIAV and CTAV revealed that 98 patients were within the limits of agreement, and the plot distribution showed no trend. The measurement method for assessing femoral anteversion using the hip post axis on the lateral hip image based on a tabletop plane parallel to the floor during surgery demonstrated sufficient accuracy for indicating anteversion in femoral trochanteric fractures.

The Influence of Pelvic Tilt and Femoral Torsion on Hip Biomechanics: Implications for Clinical Assessment and Treatment

Background: Hip biomechanics are crucial in understanding movement disorders and joint pathologies. Pelvic tilt and femoral torsion are key factors influencing hip function and stability. This review aims to elucidate their effects on acetabular orientation, hip range of motion (ROM), and associated compensatory mechanisms. Methods: A comprehensive search of databases, including PubMed, Scopus, and Pedro, was conducted. Studies were selected based on Population, Concept, and Context (PCC) criteria, focusing on those examining the relationship between pelvic tilt, femoral torsion, and hip biomechanics. Eight studies were included, utilizing methodologies such as CT imaging, musculoskeletal modeling, and gait analysis, covering populations ranging from asymptomatic adults to elderly women with pelvic retroversion. Results: The review identified significant effects of pelvic retroversion on acetabular anteversion and hip extension. Some studies found no correlation between pelvic index (PI) and acetabular orientation, while others reported a linear increase in acetabular anteversion with pelvic retroversion. Subjects with pelvic retroversion showed greater hip extension. Additionally, femoral anteversion was linked to increased internal rotation and altered hip joint contact forces during gait, with changes in hip ROM and force distribution. No relationship was found between femoral and acetabular anteversion in patients with hip osteoarthritis. Conclusions: Pelvic tilt and femoral torsion significantly affect hip biomechanics, influencing acetabular orientation, ROM, and compensatory mechanisms. Future studies should include symptomatic populations to explore these relationships further. These findings emphasize the critical need for individualized clinical assessments and further research on symptomatic populations to enhance our understanding of pelvic tilt and femoral torsion’s impact on hip biomechanics.

Patellofemoral Instability in the Pediatric and Adolescent Population: From Causes to Treatments.

Patella instability is one of the most common knee injuries in the adolescent patient. There are several pathoanatomic risk factors which should be assessed via several modalities, including X-rays, magnetic resonance imaging (MRI), or even CT scan. We intend to review these risk factors along with the nonsurgical and surgical techniques used to prevent recurrent dislocations. We completed an extensive review of the recent literature concerning pediatric and adolescent patellar dislocation and subsequent treatment modalities. We review in detail the risk factors such as patella alta, trochlear dysplasia, lateralization of the tibial tubercle or medialization of the trochlear groove (increased tibial tubercle to trochlear groove (TT-TG) distance), lower limb malalignment, excessive femoral anteversion and/or tibial torsion, and hyperlaxity. There are classification systems for dislocators, and a natural progression of instability that patients often proceed through. Only after a patient has continued to dislocate after bracing and physical therapy is surgical treatment considered. Surgical techniques vary, with the workhorse being the medial patellofemoral ligament (MPFL) reconstruction. However, there are a variety of other techniques which add onto this procedure to address other anatomic risk factors. These include the tibial tubercle osteotomy to address a large TT-TG distance or trochleoplasty to address the lack of a trochlear groove. Nonsurgical and surgical treatments for patella dislocators are tailored to the pathoanatomic risk factors in each patient.

Adjustment of stem anteversion using tapered cone stem in total hip arthroplasty.

The aim of this study was to evaluate the suitability of the tapered cone stem in total hip arthroplasty (THA) in patients with excessive femoral anteversion and after femoral osteotomy. We included patients who underwent THA using Wagner Cone due to proximal femur anatomical abnormalities between August 2014 and January 2019 at a single institution. We investigated implant survival time using the endpoint of dislocation and revision, and compared the prevalence of prosthetic impingements between the Wagner Cone, a tapered cone stem, and the Taperloc, a tapered wedge stem, through simulation. We also collected Oxford Hip Score (OHS), visual analogue scale (VAS) satisfaction, and VAS pain by postal survey in August 2023 and explored variables associated with those scores. Of the 58 patients (62 hips), two (two hips) presented with dislocation or reoperation, and Kaplan-Meier analysis indicated a five-year survival rate of 96.7% (95% CI 92.4 to 100). Mean stem anteversion was 35.2° (SD 18.2°) for the Taperloc stem and 29.8° (SD 7.9°) for the Wagner Cone stem; mean reduction from Taperloc to Wagner Cone was 5.4° (SD 18.8°). Overall, 55 hips (52 patients) were simulated, and the prevalence of prosthetic impingement was lower for the Wagner Cone (5.5%, 3/55) compared with the Taperloc (20.0%, 11/55) stem, with an odds ratio of 0.20 (p = 0.038). Among the 33 respondents to the postal survey (36 hips), the mean scores were VAS pain 10.9, VAS satisfaction 86.9, and OHS 44.7. A multivariable analysis revealed that reduction of stem anteversion from Taperloc to Wagner Cone was more favourable for VAS pain (p = 0.029) and VAS satisfaction (p = 0.002). The mid-term survival rate for THA using the Wagner Cone stem was high, which may be supported by a reduction in prosthetic impingement. The reduction in excessive stem anteversion by using a tapered cone stem was associated with reduced pain and increased patient satisfaction.

Influence of hip prosthesis position on postoperative gait in symptomatic hip osteoarthritis secondary to hip dysplasia patients after primary total hip arthroplasty: a short-term follow-up study

BackgroundThe aim of this study was to analyze the influence of the positioning of the components of total hip arthroplasty (THA) evaluated by the acetabular anteversion (AA) and femoral anteversion (FA) angle on postoperative gait in patients with symptomatic hip osteoarthritis secondary to hip dysplasia undergoing THA.MethodsBetween May 2023 and May 2024, patients with symptomatic hip osteoarthritis secondary to hip dysplasia (Crowe Type I and IV) who underwent THA were enrolled in the study. The AA angle and FA angle were measured by computer tomography (CT). Gait data were determined by using the Dynamic Right Gait & Posture analysis system. The relationship between FA, AA and gait data was analyzed by Pearson correlation test, subgroup Pearson correlation test, multiple linear regression.ResultsA total of 40 patients (45hips) were included in the study. Compared with preoperative, the patient’s postoperative foot progression angle, foot contact angle, plantarflexion velocity, swing foot speed, gait velocity, cadence, stride length were significantly improved. Preoperative FA is significantly different from postoperative FA (P < 0.05), while the difference between preoperative and postoperative AA is not significant. BMI, Crowe Type, AA were related to change of cadence. The less the postoperative AA of patients, and the more the cadence in the postoperative gait of patients.ConclusionOur study showed that THA could improve the gait function of patients with symptomatic hip osteoarthritis secondary to hip dysplasia. Adjusting AA lower could obtain a much more postoperative cadence.

Association Between Hip Translation and Hip Rotation and Anatomy: A Pilot Quasi-static MRI Study.

There is little known about translation of the hip and the relationship with hip rotation and morphology in asymptomatic patients. (1) Femoral head would exhibit significant translations in asymptomatic hips, (2) femoral head translations would correlate to femoral rotations, and (3) range of femoral head translations would correlate to hip morphology. Cross-sectional study; Level of evidence, 3. A total of 11 individuals (age, 23-47 years; 64% female) with asymptomatic hips underwent hip magnetic resonance imaging (MRI) in the following postures: neutral (supine), midflexion, maximum-flexion, internal rotation, internal rotation + midflexion, internal rotation + maximum-flexion, adduction, flexion-abduction-external rotation (FABER), extension, and lateral abduction. All rotations were passive. MRI-generated 3-dimensional hip models were used to quantify femoral rotations and translations. Femoral head diameter, acetabular diameter, lateral center-edge angle, alpha angle, femoral anteversion, acetabular version and inclination, and neck-shaft angle were measured from MRI. A t test was used if measured translations were statistically significant. Linear regression was used to assess the associations between translation and rotation. Pearson correlation was used to assess the relationships between hip anatomy and range of femoral head translations. In all tested positions, the femoral head translated anteriorly by 2 ± 1 mm (maximum 5 mm, P < .001), posteriorly by 1 ± 1 mm (maximum 6 mm, P < .001), superiorly by 2 ± 2 mm (maximum 7 mm, P < .001), inferiorly by 2 ± 2 mm (maximum 6 mm, P < .001), laterally by 1 ± 1 mm (maximum 4 mm, P < .001), and medially by 2 ± 1 mm (maximum 5 mm, P < .001), relative to the rested supine position. Femoral flexion was associated with posterior translation of the femoral head (P = .038). Femoral abduction was associated with medial translation of the femoral head (P = .042). Higher femoral anteversion and smaller alpha angle were associated with a higher total magnitude of femoral head translation in the anterior-posterior direction (P < .04). Smaller femoral anteversion, higher acetabular inclination, smaller lateral center-edge angle, and lower neck-shaft angle were associated with a higher total magnitude of femoral head translation in the superior-inferior direction (P ≤ .03). Our study demonstrated that, during passive physiologic movement, asymptomatic hips on average translated up to 2 mm (with up to 7 mm maximum translation in some positions), which is potentially related to hip rotations and morphology. Further investigations are warranted to understand the normal and pathologic hip translations and their impact on hip function (ie, instability and impingement).

Intraoperative estimation of natural femoral anteversion from proximal femoral osseous orientation during total hip arthroplasty

BackgroundThe purpose of this study was to elucidate the relationship between the orientation of the osseous structure of the proximal femur encountered during total hip arthroplasty (THA) and preoperative femoral anteversion (FA).MethodsThree-dimensional models were constructed using full-length lower extremity computed tomography images from a total of 80 participants. Femoral neck cutting was performed at heights of 5, 10, and 15 mm relative to the lesser trochanter. Following neck cutting, the angles formed by the anterior outer cortex and posterior outer cortex with the posterior condylar line (PCL) were defined as the anterior cortical angle (ACA) and posterior cortical angle (PCA), respectively. Univariate linear regression analysis was conducted using the remaining measurements with FA as the dependent variable.ResultsThe mean age of the participants was 60.98 ± 10.82 years (males, 60.50 ± 11.36 years; females, 61.45 ± 10.37 years) (p = 0.697). All cortical angles and FA were larger in women compared to those in men. When comparing measurements by age groups, no statistically significant differences were observed. Univariate linear regression analysis with FA as the dependent variable showed statistical significance for all cortical angles. The adjusted R2 values were 0.711 (ACA5), 0.677 (ACA10), 0.572 (ACA15), 0.493 (PCA5), 0.574 (PCA10), and 0.446 (PCA15).ConclusionNatural FA can be inferred from the anterior cortical angle (ACA) from femoral neck cutting plane observed during the THA procedure without preoperative images.Trial registrationRetrospectively registered.

Understanding the variability of the proximal femoral canal: A computational modeling study.

Statistical shape modeling (SSM) offers the potential to describe the morphological differences in similar shapes using a compact number of variables. Its application in orthopedics is rapidly growing. In this study, an SSM of the intramedullary canal of the proximal femur was built, with the aim to better understanding the complexity of its shape which may, in turn, enhance the preoperative planning of total hip arthroplasty (THA). This includes the prediction of the prosthetic femoral version (PFV) which is known to be highly variable amongst patients who have undergone THA. The model was built on three dimensional (3D) models of 64 femoral canals which were generated from pelvic computed tomography images including the proximal femur in the field of view. Principal component analysis (PCA) was performed on the mean shape derived from the model and each segmented canal. Five prominent modes of variations representing approximately 84% of the total 3D variations in the population of shapes were found to capture variability in size, proximal torsion, intramedullary femoral anteversion, varus/valgus orientation, and distal femoral shaft twist/torsion, respectively. It was established that the intramedullary femoral canal is highly variable in its size, shape, and orientation between different subjects. PCA-driven SSM is beneficial for identifying patterns and extracting valuable features of the femoral canal.