Accuracy and Reliability of Computed Tomography and Magnetic Resonance Imaging Compared With True Anatomic Femoral Version

Exploring the Relationship Between Combined, Acetabular, and Femoral Version on Postoperative Outcomes 2 Years After Hip Arthroscopy for Femoroacetabular Impingement Syndrome

BACKGROUND

Many studies have examined the prevalence of acetabular version (AV) and femoral version (FV) abnormalities and their effect on patient-reported outcomes (PROs) after hip arthroscopy for femoroacetabular impingement syndrome (FAIS), but few have explored the prevalence and influence of combined version (CV) abnormalities.

PURPOSE

To (1) describe the distribution of AV, FV, and CV in the largest cohort to date and (2) determine the relationship between AV, FV, and CV and PROs after hip arthroscopy for FAIS.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients were identified who underwent primary hip arthroscopy for FAIS between 2012 and 2018 and received computed tomography containing the pelvis and transcondylar knee slices. AV and FV were assessed on computed tomography, with CV calculated as their sum. PROs were collected preoperatively and 2 years postoperatively. The distributions of AV, FV, CV, and combinations thereof were described based on published ranges. The relationships between version measurements and PROs were analyzed based on a given measurement's distance from a normative value, defined as the mean within the study population (eg, relative acetabular anteversion [AAr]). These relationships were first assessed using univariate natural (restricted) cubic regression splines to account for nonlinearity. The relationship between each relative version group (to the mean) and PROs was then assessed using multiple linear regression, with the other 2 version measurements held constant.

RESULTS

In total, 566 patients were included (66.4% female; mean age, 32.6 ± 11.9 years; mean body mass index, 25.2 ± 5.1). The mean follow-up was 28.0 months. The mean AV, FV, and CV were 17.1°± 5.2°, 12.1°± 9.2°, and 29.3°± 11°, respectively. Univariate natural cubic regression splines demonstrated that AAr had a significant negative association with 4 of 5 PROs preoperatively and 3 of 5 PROs 2 years postoperatively (P≤ .018). All other relative version groups did not have a significant relationship with any PRO at either time point (P > .05). The association between AAr and relatively worse PROs was maintained after controlling for relative FV and CV via multiple linear regression, particularly in patients with relative femoral retroversion.

CONCLUSION

FV and CV, as distinct measures, are not associated with outcomes after hip arthroscopy for FAIS. AAr is associated with worse preoperative status and less improvement at 2 years postoperatively, particularly in patients with relative femoral retroversion.

The Principles of Hip Joint Preservation

The three primary factors involved in preservation of the hip joint include femoroacetabular impingement (FAI), hip dysplasia/instability, and femoral torsion abnormalities. Each of these factors affects the health of the acetabular labrum and femoroacetabular cartilage. The appropriate surgical treatments for each of these factors include arthroscopic or open femoroplasty/acetabuloplasty for FAI, periacetabular osteotomy for hip dysplasia/instability, and derotational femoral osteotomy for femoral torsion abnormalities. When evaluating patients with prearthritic hip conditions, orthopaedic surgeons should be aware of the various factors involved in hip joint preservation and, if surgery is indicated, the surgeon should be sure to address all factors that need surgical treatment rather than focusing on the commonly diagnosed issue or visible injury, for example, a labral tear. If any of these factors is ignored, the hip joint may not thrive. The purpose of this review was to explain the importance of the most common factors involved in hip joint preservation and the appropriate surgical treatments for pathology in these factors.

Normative Measurements of L1 to S1 Neuroforaminal Dimensions Derived From Plain Film Radiography, Computed Tomography, and Magnetic Resonance Imaging

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

To report normative measurements of L1 to S1 lumbar neuroforamina on plain film radiography (PFR), computed tomography (CT), and magnetic resonance imaging (MRI), accounting for patients' sex and ethnicity.

BACKGROUND

The quantitative criteria fothe diagnosis of neuroforaminal stenosis remains unknown. Acquiring a thorough understanding of normative foraminal dimensions is a key step in formulating objective parameters for neuroforaminal stenosis.

PATIENTS AND METHODS

We measured 988 images from 494 patients between 18 and 35 years old without spinal pathology who received PFR, CT, or MRI within 1 year of each other. Neuroforaminal measurements were defined as the height, area, and sagittal and axial widths. Statistical analyses were performed to assess relationships among PFR, CT, and MRI-derived neuroforaminal measurements, as well as the influence of patients' sex and ethnicity.

RESULTS

330 PFR, 377 CT, and 281 MRI were measured. Of these, 213 PFR and CT, 117 PFR and MRI, and 164 MRI and CT intrapatient images were compared. Statistically significant differences were observed among PFR, CT, and MRI measurements across all levels L1 to S1. PFR measurements were larger compared with those derived from CT and MRI. Weak-to-moderate correlations were observed between PFR and CT, PFR and MRI, and CT and MRI, with the magnitude of correlation decreasing caudally from L1 to S1. Variations in neuroforaminal anatomy were observed based on sex and ethnicity.

CONCLUSION

This study reports 25,951 measurements of normal L1 to S1 neuroforaminal anatomy assessed by PFR, CT, and MRI. The values reported in this study may be used as normative reference measurements of the lumbar neuroforamina. PFR measurements of the neuroforamina are larger compared with those derived from CT and MRI across all levels from L1 to S1. There is a poor correlation between PFR, CT, and MRI when measuring the lumbar neuroforamina. Differences in neuroforaminal anatomy are evident based on patients' sex and ethnicity.

MRI-based torsion measurement of the lower limb is a reliable and valid alternative for CT measurement: a prospective study

PURPOSE

The aim of this study was to compare MRI-based torsion measurements of the lower limb to a well-established CT-based assessment in a prospective inter- and intraindividual approach.

METHODS

A total of 26 patients (age 28.8 years ± 11.0) were enrolled beginning in January 2021 until August 2022. Inclusion criteria were the clinical indication for torsion measurement of the lower limb. CT and MRI imaging were performed with a standard operating procedure, to ensure that all patients were examined in a standardized position. The examinations were planned on a coronal scout view based on prominent anatomical landmarks. Femoral and tibial torsion were measured individually. Torsion measurements were analysed twice: immediately after examination and after 3 weeks. Subsequently, intra-rater and parallel test reliability was calculated accordingly.

RESULTS

High significant results for CT and MRI measurements for both tibia (MRI: r = 0.961; p ≤ 0.001; CT: r = 0.963; p ≤ 0.001) and femur (MRI: r = 0.980; p ≤ 0.001; CT: r = 0.979; p ≤ 0.001) were obtained by calculated intra-rater reliability, showing that measurements were highly consistent for MRI and CT, respectively. Parallel test reliability for time point 1 as well as time point 2 was also highly significant and ranged from r = 0.947 to r = 0.972 (all with p ≤ 0.001, respectively) for both tibia and femur, showing a high concordance between the two measurements.

CONCLUSION

Measurement of tibial as well as femoral torsion was comparable for CT and MRI measurement. Therefore, this study supports MRI measurement as an equivalent alternative for CT measurement concerning torsional malalignment to reduce exposure to radiation.

LEVEL OF EVIDENCE

Level II.

Effect of Differing Orientation and Magnitude of Femoral Torsion on Outcomes and Achievement of the MCID and PASS at 5 Years After Hip Arthroscopy for Femoroacetabular Impingement Syndrome

BACKGROUND

Femoral torsion measurements and outcomes are variable throughout the literature and have focused on short-term follow-up. However, there is a paucity of literature investigating clinically meaningful outcomes at midterm follow-up after hip arthroscopy for femoroacetabular impingement syndrome (FAIS).

PURPOSE

To quantify femoral version using computed tomography imaging in patients with FAIS and to explore the relationship between version abnormalities and 5-year outcomes after hip arthroscopy.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients who underwent primary hip arthroscopy for FAIS between January 2012 and November 2017 were identified. Patients were included if they had 5-year follow-up with completion of ≥1 patient-reported outcome (PRO) scores and excluded if they had Tönnis grade >1, revision hip surgery, a concomitant hip procedure, a developmental disorder, or a lateral center-edge angle <20°. Torsion groups were defined as severe retrotorsion (<0°), moderate retrotorsion (0.1°-5°), normal torsion (5.1°-20°), moderate antetorsion (20.1°-25°), and severe antetorsion (>25.1°) based on computed tomography measurements. Patient characteristics were analyzed among the torsion cohorts, as were preoperative and 5-year PROs: Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sports Subscale, modified Harris Hip Score, international Hip Outcome Tool, visual analog scale for pain, and visual analog scale for satisfaction. Achievement rates of cohort-specific thresholds for the minimal clinically important difference and Patient Acceptable Symptom State were calculated and compared among cohorts.

RESULTS

A total of 362 patients (244 female, 118 male; mean ± SD age, 33.1 ± 11.5 years; body mass index, 26.9 ± 17.8) met inclusion/exclusion criteria and were analyzed at a final mean follow-up of 64.3 ± 9.4 months (range, 53.5-115.5 months). Mean femoral torsion was 12.8°± 9.2°. The number of patients within each group was 20 for severe retrotorsion (torsion, -6.3°± 4.9°), 45 for moderate retrotorsion (2.7°± 1.3°), 219 for normal torsion (12.2°± 4.1°), 39 for moderate antetorsion (21.9°± 1.3°), and 39 for severe antetorsion (29.0°± 4.2°). No significant differences in age, body mass index, sex, smoking status, workers' compensation, psychiatric history, back pain, or physical activity were found among the torsional groups. All groups demonstrated significant improvements at 5 years postoperatively (P < .01 for all). All torsion subgroups demonstrated similar pre- to postoperative changes in PROs (P≥ .515) and PRO values at 5-year follow-up (P≥ .098). There were no significant differences in the achievement of the minimal clinically important difference (P≥ .422) or Patient Acceptable Symptom State (P≥ .161) for any of the PROs among the torsion groups.

CONCLUSION

The orientation and severity of femoral torsion at the time of hip arthroscopy for FAIS in this study's cohort did not affect the propensity for clinically meaningful outcome improvement at midterm follow-up.

Interobserver reliability of biplanar radiography is unaffected by clinical factors relevant to individuals at risk of pathological lower limb torsion

BACKGROUND

Assessments of lower limb torsion are ubiquitous in clinical gait analysis practice as pathologic lower limb rotational deformity may contribute to gait abnormalities, anterior knee pain, as well as other debilitating conditions. Understandably, the overall utility of any torsional assessment is dependent on the measurement method's intrinsic accuracy, precision, and robustness to clinical interference factors. Recently, biplanar radiography (BPR) measurements of torsion have been shown to be both accurate and precise, but the robustness of BPR to potential interference factors is unknown.

RESEARCH QUESTION

How robust are BPR lower limb torsional assessments to six potential interference factors: amount of torsion, skeletal maturity, radiograph quality, prior osteotomy, presence of implants, and observer training background and experience?

METHODS

In this retrospective cohort study, four observers of diverse backgrounds and experience generated digital 3D reconstructions of 44 lower limbs using BPR images obtained during standard of care visits (age range 7-35 years). From each reconstruction, four lower limb torsional parameters were computed: femoral torsion, femorotibial rotation, tibial torsion, and transmalleolar axis equivalent. The mean absolute deviation (MAD) of each torsional parameter - calculated across the four observers - was used as the measure of reliability and tested against all interference factors.

RESULTS

Results demonstrated that the average MAD was 2.1 degrees for femoral torsion, 3.0 degrees for transmalleolar axis equivalent, 3.8 degrees for femorotibial rotation, and 4.7 degrees for tibial torsion. None of the six potential interference factors were found to systematically influence BPR reliability across all four torsional parameters. Of the factors found to statistically influence one or more torsional parameter, none affected MAD values to a clinically meaningful extent.

SIGNIFICANCE

In addition to being accurate and precise, BPR appears to be robust to several clinical factors relevant to children and young adults with or at risk for pathological lower limb torsion.

Evaluating the Need for Preoperative MRI Before Primary Hip Arthroscopy in Patients 40 Years and Younger With Femoroacetabular Impingement Syndrome: A Multicenter Comparative Analysis

Background

Routine hip magnetic resonance imaging (MRI) before arthroscopy for patients with femoroacetabular impingement syndrome (FAIS) offers questionable clinical benefit, delays surgery, and wastes resources.

Purpose

To assess the clinical utility of preoperative hip MRI for patients aged ≤40 years who were undergoing primary hip arthroscopy and who had a history, physical examination findings, and radiographs concordant with FAIS.

Study Design

Cohort study; Level of evidence, 3.

Methods

Included were 1391 patients (mean age, 25.8 years; 63% female; mean body mass index, 25.6) who underwent hip arthroscopy between August 2015 and December 2021 by 1 of 4 fellowship-trained hip surgeons from 4 referral centers. Inclusion criteria were FAIS, primary surgery, and age ≤40 years. Exclusion criteria were MRI contraindication, reattempt of nonoperative management, and concomitant periacetabular osteotomy. Patients were stratified into those who were evaluated with preoperative MRI versus those without MRI. Those without MRI received an MRI before surgery without deviation from the established surgical plan. All preoperative MRI scans were compared with the office evaluation and intraoperative findings to assess agreement. Time from office to arthroscopy and/or MRI was recorded. MRI costs were calculated.

Results

Of the study patients, 322 were not evaluated with MRI and 1069 were. MRI did not alter surgical or interoperative plans. Both groups had MRI findings demonstrating anterosuperior labral tears treated intraoperatively (99.8% repair, 0.2% debridement, and 0% reconstruction). Compared with patients who were evaluated with MRI and waited 63.0 ± 34.6 days, patients who were not evaluated with MRI underwent surgery 6.5 ± 18.7 days after preoperative MRI. MRI delayed surgery by 24.0 ± 5.3 days and cost a mean $2262 per patient.

Conclusion

Preoperative MRI did not alter indications for primary hip arthroscopy in patients aged ≤40 years with a history, physical examination findings, and radiographs concordant with FAIS. Rather, MRI delayed surgery and wasted resources. Routine hip MRI acquisition for the younger population with primary FAIS with a typical presentation should be challenged.

Correlation of femoral version measurements between computed tomography and magnetic resonance imaging studies in patients presenting with a femoroacetabular impingement-related complaint

Computed tomography (CT) is considered the gold standard for femoral version measurement. However, recent data have shown magnetic resonance imaging (MRI) as another modality to measure femoral version. This study aimed to correlate MRI and CT femoral version measurements in patients presenting with a femoroacetabular impingement (FAI)-related complaint. Patients (18-35 years old) who presented to the hip preservation clinic and radiology department with a suspected FAI diagnosis from 26 December 2018 to 4 March 2020 were included. All patients had a CT and MRI of the hip, with images including both hips and knees, as per our institution's protocol for possible hip preservation surgery. Patients were excluded if they were missing views of the knees, or if they had a history or imaging appearance of any condition affecting femoral version at the femoral head (e.g. slipped capital femoral epiphysis). Femoral version was measured by three reviewers. Fifty-eight patients were included, and 36 (62%) were female. Femoral version averaged 6.1° ± 11.8° on CT and 6.5° ± 10.8° on MRI. A strong positive correlation was reported between the two imaging modalities (r: 0.81; P < 0.001). Inter-rater reliability among the three reviewers was excellent and statistically significant for measurements on both MRI [intraclass correlation coefficient (ICC): 0.95; 95% CI: 0.85, 0.99; P < 0.001] and CT (ICC: 0.97; 95% CI: 0.92, 0.99; P < 0.001). Our finding suggests that MRI is a sufficient method for measuring femoral version to determine disease etiology and treatment progression. To avoid exposing patients to ionizing radiation, physicians should not obtain CT scans to evaluate femoral version.

Rotational Osteotomy for Femoral Version/Tibial Torsion

PURPOSE OF REVIEW

The purpose of this review is to discuss the current state of knowledge regarding axial plane deformities in patellofemoral instability, indications and techniques for treatment of those deformities, and outcomes following treatment.

RECENT FINDINGS

There is opportunity for more information in the literature on all aspects of axial plane deformities in patellofemoral instability. This includes how to assess axial plane deformities on imaging, what is normal and what is an appropriate goal for correction, what techniques are best used depending on the deformity or concomitant pathology, and larger and more discriminating studies on outcomes. Rotational deformity of both the tibia and femur is an important risk factor to consider as a cause of patellar instability. Recent research has shown that surgical correction of these deformities on either the femoral or tibial side can have a positive effect on outcome in terms of patellar instability and knee pain. Further research, however, is warranted to determine what are normal values for femoral version and tibial torsion, and at what values surgical intervention is warranted.

3D Gait Analysis and Patient-reported Outcomes of Femoral Osteotomies for Torsional Deformity

BACKGROUND

Idiopathic torsional deformities causing pain and/or functional difficulty is an indication for a femoral derotational osteotomy (FDRO). Past studies have focused entirely on children with internal femoral torsional deformity (IFTD). This study aims to compare gait and outcomes between children with IFTD and those with external femoral torsional deformity (EFTD) after a FDRO.

METHODS

A retrospective review of all patients who underwent an FDRO between 1997 and 2020 at our institution. Data on typically developing (TD) children with no torsional deformity was used as a control group. We analyzed preoperative and postoperative standardized physical examination, 3-dimensional gait analysis, and Pediatric Outcomes Data Collection Instrument questionnaires.

RESULTS

There were 54 patients in total (IFTD=37, EFTD=17) and 20 patients in the control group. The EFTD cohort was older (IFTD=11.7, EFTD=14.7, P <0.05) and had a higher body mass index both preoperatively (IFTD=21.1 kg/m 2 , EFTD=32.1 kg/m 2 , P <0.05) and postoperatively (IFTD=20.2 kg/m 2 , EFTD=34.1 kg/m 2 , P <0.05). Preoperatively, 3-dimensional gait analysis elicited mean hip rotation in stance was more internal for IFTD cohort (10.8 degrees) and external for the EFTD cohort (-17.8 degrees) in comparison to the TD (2.4 degrees, P <0.001). Postoperatively, dynamic mean hip rotation during stance was -1.4 degrees for IFTD, whereas for EFTD, it was -5.4 degrees, which was different to the TD ( P <0.05). The IFTD group's Pediatric Outcomes Data Collection Instrument improved for transfer/basic mobility, sports/physical function, global functioning, and satisfaction with symptoms ( P <0.05). The EFTD group that only reported an improvement with the satisfaction with symptoms after surgery ( P <0.05).

CONCLUSIONS

Adolescents with surgically corrected IFTD show more improvement in gait and in patient-reported outcomes than those with surgically corrected EFTD. Children with EFTD persist in external rotation and have less satisfactory patient-reported outcomes after a FDRO in comparison those with IFTD.

LEVEL OF EVIDENCE

Level III-retrospective comparative study.

MRI quantification of femoral neck version using the posterior lesser trochanteric line: a comparison of three measurements

OBJECTIVE

To validate MRI for the quantification of the femoral neck version (FNV) using posterior lesser trochanteric Line (PLTL) and to compare reliability of the PLTL to the epicondylar and retrocondylar measurements.

MATERIALS AND METHODS

A retrospective review of 3 T MRI scans performed for femoroacetabular impingement (FAI). Two musculoskeletal radiologists performed the measurements. MRI measurements of the PLTL were compared to CT using Bland Altman, Lin's concordance, and Lin's correlation coefficients. Interobserver reliability was determined using Bland Altman, Lin's concordance, and Lin's correlation coefficients. Intraobserver reliability was determined using Lin's concordance and Lin's correlation coefficients.

RESULTS

Forty-five patients (90 lower extremities) met the inclusion criteria. Ages ranged from 20 to 41 years, with a mean of 31.5 years. There were 22 females and 23 males. Lin's concordance correlation coefficient for MRI and CT measurements of PLTL was substantial: 0.96 (95% CI: 0.94-0.98). PLTL Lin's correlation coefficient was 0.825 (95% CI 0.732-0.918) and indicated good interobserver reliability. Epicondylar and retrocondylar methods Lin's correlation coefficients demonstrated moderate interobserver reliability at 0.601 (0.415-0.786) and 0.632 (0.456-0.807), respectively. There was moderate 95% confidence interval overlap between the PLTL and the other measurements. Bland-Altman plots for each measurement were similar and demonstrated no bias. There was excellent intraobserver reliability (> 0.900) with significant 95% confidence interval overlap.

CONCLUSION

MRI measurements of the PLTL are comparable to CT. The PLTL has good reliability between readers for the quantification of FNV using MRI, which could help avoid unnecessary radiation exposure using CT and reduce MRI scan time.

A new factor predicting excessive femoral anteversion in patients with recurrent patellar dislocation

PURPOSE

Determining a new imaging method on full-leg standing lower limb radiographs to predict excessive femoral anteversion in patients with patellar dislocation.

METHODS

This study included 119 patients with patellar dislocation from January 2014 to January 2021. The femoral anteversion and tibial torsion were measured by CT scanning. The medial condylar angle was measured by the full-leg standing lower limb radiographs. Pearson correlation coefficient was used to evaluate the correlation between rotation parameters and medial condylar angle.

RESULTS

Included patients were divided into DFO group and control group according to whether they received derotational femoral osteotomy (DFO) operation or not. DFO group had significantly higher femoral anteversion (29.8° ± 7.2° vs 23.1° ± 6.5°, P < 0.05), higher tibial torsion (28.6° ± 6.9° vs 24.7° ± 7.9°, P < 0.05), lower medial condylar angle (154.8° ± 4.7° vs 157.5° ± 6.7°, P < 0.05) than control group. Correlation analysis showed that the values of femoral anteversion were significantly correlated with medial condylar angle (r = -0.719, P < 0.001).

CONCLUSION

This study showed that medial condylar angle had a negative correlation with excessive femoral anteversion on the full-leg standing lower limb radiographs. The medial condylar angle can be a good predictor of femoral anteversion and can be used to guide the performance of DFO to treat patellar dislocation in clinical practice.

Assessment of Femoral Torsion on Magnetic Resonance Imaging is More Reliable Using Axial-Oblique Sequences Compared With Standard Axial Slices in Patients With Femoroacetabular Impingement Syndrome

PURPOSE

To determine the agreeability of femoral torsion measurements on axial and oblique axial magnetic resonance imaging (MRI) sequences in patients with femoroacetabular impingement syndrome (FAIS).

METHODS

Patients who underwent primary hip arthroscopy for FAIS between January 2012 to January 2019 were identified. Inclusion criteria were all patients with an MRI scan containing the pelvis and knee imaging. MRI-based measurements of femoral torsion were performed on axial and oblique-axial slices by 2 raters, and inter-rater and intrarater reliability was assessed. Bland Altman plots were constructed to evaluate the agreeability between femoral torsion measurements performed using axial and oblique-axial slices. Bivariate correlation analyses were performed to assess the relationship between measurement methods on each respective scan. A linear regression was performed between measurements performed using axial and oblique-axial sequences.

RESULTS

A total of 164 patients were included. The mean true-axial and oblique axial femoral torsion were 12.2° ± 9.9° and 11.1° ± 9.2°, respectively. The intrarater reliability for axial and oblique-axial measurements were 0.993 and 0.997, respectively. The inter-rater reliability for axial and oblique-axial measurements were 0.925 and 0.965, respectively. The number of differences within the limits of agreement for axial and oblique-axial femoral torsion measurements was 58.54%. On Pearson correlation analysis, strong positive correlations were found between oblique-axial measurements at multiple time points (r = 0.994, P < .001), as well as axial measurements at multiple time points (r = 0.986, P < .001). A strong positive correlation was found between axial and oblique-axial measurements (r = 0.894, P < .001). A significant regression equation indicated that for each additional increase in axial femoral torsion, the oblique-axial femoral torsion increased 0.837 (95% confidence interval 0.772-0.901).

CONCLUSIONS

Femoral torsion values measured on oblique-axial sequences are smaller than on true-axial sequences. Femoral torsion measurements on axial and oblique-axial MRI sequences exhibit poor agreement. Oblique-axial sequences demonstrated greater measurement consistency at multiple timepoints. When evaluating torsional measurements, it is important to delineate which axial sequence was used, especially in patients with suspected severe femoral antetorsion. Standardization of MRI femoral version protocols within one's practice can ensure more consistent decision-making, especially in patients with suspected femoral antetorsion.

LEVEL OF EVIDENCE

Retrospective cohort, level III.

Utility of a novel integrated deep convolutional neural network for the segmentation of hip joint from computed tomography images in the preoperative planning of total hip arthroplasty

Purpose

Preoperative three-dimensional planning is important for total hip arthroplasty. To simulate the placement of joint implants on computed tomography (CT), pelvis and femur must be segmented. Accurate and rapid segmentation of the hip joint is challenging. This study aimed to develop a novel deep learning network, named Changmugu Net (CMG Net), which could achieve accurate segmentation of the femur and pelvis.

Methods

The overall deep neural network architecture of CMG Net employed three interrelated modules. CMG Net included the 2D U-net to separate the bony and soft tissues. The modular hierarchy method was used for the main femur segmentation to achieve better performance. A layer classifier was adopted to localise femur layers among a series of CT scan images. The first module was a modified 2D U-net, which separated bony and soft tissues; it provided intermediate supervision for the main femur segmentation. The second module was the main femur segmentation, which was used to distinguish the femur from the acetabulum. The third module was the layer classifier, which served as a post-processor for the second module.

Results

There was a much greater overlap in accuracy results with the “gold standard” segmentation than with competing networks. The dice overlap coefficient was 93.55% ± 5.57%; the mean surface distance was 1.34 ± 0.24 mm, and the Hausdorff distance was 4.19 ± 1.04 mm in the normal and diseased hips, which indicated greater accuracy than the other four competing networks. Moreover, the mean segmentation time of CMG Net was 25.87 ± 2.73 s, which was shorter than the times of the other four networks.

Conclusions

The prominent segmentation accuracy and run-time of CMG Net suggest that it is a reliable method for clinicians to observe anatomical structures of the hip joints, even in severely diseased cases.

Femoral neck shaft angle is not correlated with femoral version: A retrospective study of computed tomography scans

BACKGROUND

An understanding of femoral anteversion and neck-shaft angle (NSA) is essential to deliver optimal orthopaedic surgical care. Despite the importance, there is little research examining the relationship between femoral anteversion and the NSA in an adult population. This study sought to determine if there is a correlation between femoral neck shaft angle and version in skeletally mature adults using computed tomography (CT) scanograms.

METHODS

Between January 2010 and June 2017, all skeletally mature patients who had received a CT scanogram of the lower extremity were reviewed. Exclusion criteria included: (1) radiographic evidence of osteoarthritis, (2) history of hip, femur, or knee surgery or trauma, (3) and anatomic abnormalities of the proximal femur including prior slipped capital femoral epiphysis or Legg-Calvé-Perthes disease. Both femoral version and NSA were measured by a musculoskeletal fellowship trained radiologist using CT scanograms. Correlation between femoral version and NSA was determined using coefficient of determination (R²) and Pearson correlation coefficient (r) for the group as a whole and for each sex.

RESULTS

There was no statistical correlation between femoral version and NSA for either the entire cohort or for each sex. For the entire cohort, R² = 0.0016 and r was 0.04 (p=0.45), for females, R² = 0.0005 and r was 0.0224 (p=0.72), and for males, R² = 0.0342 and r was 0.185 (p=0.07).

CONCLUSION

There was no correlation between femoral version and NSA. This finding is beneficial for surgeons to understand the proximal femoral anatomy. Patients with an increased femoral NSA should not be assumed to have increased femoral anteversion.

LEVEL OF EVIDENCE

Level III, Retrospective Cohort Study.

Rotational Deformity-When and How to Address Femoral Anteversion and Tibial Torsion

Rotational deformity is a less common cause of patellar instability than trochlear dysplasia and patella alta. In some cases, rotational deformity is the primary bony factor producing the instability and should be corrected surgically. More research is needed on what are normal values for femoral version and tibial torsion, as well as when the axial plane alignment needs to be corrected. Many tools can be used to evaluate the axial plane and surgeons should be familiar with each of them. Understanding the advantages and disadvantages of each site for osteotomy will help the surgeon choose the most appropriate osteotomy.

Influence of Femoral Version on the Outcomes of Hip Arthroscopic Surgery for Femoroacetabular Impingement or Labral Tears: A Systematic Review and Meta-analysis

BACKGROUND

It remains controversial whether abnormal femoral version (FV) affects the outcomes of hip arthroscopic surgery for femoroacetabular impingement (FAI) or labral tears.

PURPOSE

To review the outcomes of hip arthroscopic surgery for FAI or labral tears in patients with normal versus abnormal FV.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

Embase, PubMed, and the Cochrane Library were searched in July 2020 for studies reporting the outcomes after primary hip arthroscopic surgery for FAI or labral tears in patients with femoral retroversion (<5°), femoral anteversion (>20°), or normal FV (5°-20°). The primary outcome was the modified Harris Hip Score (mHHS), and secondary outcomes were the visual analog scale (VAS) for pain, Hip Outcome Score-Sport-Specific Subscale (HOS-SSS), Non-Arthritic Hip Score (NAHS), failure rate, and patient satisfaction. The difference in preoperative and postoperative scores (Δ) was also calculated when applicable.

RESULTS

Included in this review were 5 studies with 822 patients who underwent hip arthroscopic surgery for FAI or labral tears; there were 166 patients with retroversion, 512 patients with normal version, and 144 patients with anteversion. Patients with retroversion and normal version had similar postoperative mHHS scores (mean difference [MD], 2.42 [95% confidence interval (CI), -3.42 to 8.26]; P = .42) and ΔmHHS scores (MD, -0.70 [96% CI, -8.56 to 7.15]; P = .86). Likewise, the patients with anteversion and normal version had similar postoperative mHHS scores (MD, -3.09 [95% CI, -7.66 to 1.48]; P = .18) and ΔmHHS scores (MD, -1.92 [95% CI, -6.18 to 2.34]; P = .38). Regarding secondary outcomes, patients with retroversion and anteversion had similar ΔNAHS scores, ΔHOS-SSS scores, ΔVAS scores, patient satisfaction, and failure rates to those with normal version, although a significant difference was found between the patients with retroversion and normal version regarding postoperative NAHS scores (MD, 5.96 [95% CI, 1.66-10.26]; P = .007) and postoperative HOS-SSS scores (MD, 7.32 [95% CI, 0.19-14.44]; P = .04).

CONCLUSION

The results of this review indicated that abnormal FV did not significantly influence outcomes after hip arthroscopic surgery for FAI or labral tears.

Hip Dysplasia

Acetabular dysplasia represents a structural pathomorphology associated with hip pain, instability, and osteoarthritis. The wide spectrum of dysplasia anatomically refers to a 3-dimensional volumetric- and surface area-based insufficiency in coverage and is classified based on the magnitude and location of undercoverage. Borderline dysplasia has been variably defined and leads to management challenges. In symptomatic dysplasia, treatment addresses coverage with periacetabular osteotomy. Concomitant simultaneous or staged hip arthroscopy has significant advantages to address intra-articular pathology. In nonarthritic individuals, there is evidence PAO alters the natural history of dysplasia and decreases the risk of hip arthritis and total hip arthroplasty.

Femoral anteversion: significance and measurement

Femoral neck anteversion (FNA) is the angle between the femoral neck and femoral shaft, indicating the degree of torsion of the femur. Differences in FNA affect the biomechanics of the hip, through alterations in factors such as moment arm lengths and joint loading. Altered gait associated with differences in FNA may also contribute to the development of a wide range of skeletal disorders including osteoarthritis. FNA varies by up to 30° within apparently healthy adults. FNA increases substantially during gestation and thereafter decreases steadily until maturity. There is some evidence of a further decrease at a much lower rate during adulthood into old age, but the mechanisms behind it have never been studied. Development of FNA appears to be strongly influenced by mechanical forces experienced during everyday movements. This is evidenced by large differences in FNA in groups where movement is impaired, such as children born breech or individuals with neuromuscular conditions such as cerebral palsy. Several methods can be used to assess FNA, which may yield different values by up to 20° in the same participant. While MRI and CT are used clinically, limitations such as their cost, scanning time and exposure to ionising radiation limit their applicability in longitudinal and population studies, particularly in children. More broadly, applicable measures such as ultrasound and functional tests exist, but they are limited by poor reliability and validity. These issues highlight the need for a valid and reliable universally accepted method. Treatment for clinically problematic FNA is usually de-rotational osteotomy; passive, non-operative methods do not have any effect. Despite observational evidence for the effects of physical activity on FNA development, the efficacy of targeted physical activity remains unexplored. The aim of this review is to describe the biomechanical and clinical consequences of FNA, factors influencing FNA and the strengths and weaknesses of different methods used to assess FNA.

Increased femoral anteversion related to infratrochanteric femoral torsion is associated with ACL rupture

PURPOSE

To determine the association between femoral torsion and anterior cruciate ligament (ACL) rupture and determine the level of torsion using magnetic resonance imaging (MRI).

METHODS

The medical records of patients who were diagnosed with ACL injury were reviewed retrospectively. This descriptive epidemiological study included 2344 patients. MRI scans were examined and patients with femur and knee MRI scans obtained at the same time were identified (ACL-deficient group). Twenty-eight of them had femur and knee MRI scans because of an incidental benign lesion in the distal femur. Patients who were diagnosed with enchondroma were followed up by MRI evaluation of the femur and were randomly selected as controls. Supratrochanteric torsion (STT), infratrochanteric torsion (ITT), and femoral anteversion (FA) were measured by orthopedic surgeons with at least 5 years of experience.

RESULTS

Age, sex, and side properties were similar in both groups. The mean FA values were 19.4 ± 3.0 degrees and 11.9 ± 2.0 degrees in the ACL-deficient and control groups, respectively (p < 0.001). STT was similar in the ACL-deficient and control groups [mean: 38.2 ± 4.3 and 37.7 ± 3.3, respectively, (n.s.)]. ITT was increased in the ACL-deficient group compared with the control group (mean - 18.8 ± 4.3 and - 25.8 ± 3.8, respectively; p < 0.001).

CONCLUSIONS

According to our results, increased FA was associated with ACL rupture. Further, the torsional abnormality was developed from the ITT. We concluded that each ACL-deficient patient should be assessed by a clinician for torsional abnormality using physical examination.

LEVEL OF EVIDENCE

III.

The Bipolar Hip: How Acetabular and Femoral Pathomorphology Affects Hip Motion in Femoral Acetabular Impingement Syndrome

PURPOSE

To investigate the individual and combined contributions of acetabular and femoral morphology to hip range of motion (ROM) in patients with femoroacetabular impingement syndrome (FAIS) by use of computed tomography measurements and hip ROM evaluated on physical examination.

METHODS

A retrospective chart and radiographic analysis of patients presenting with hip pain suggestive of FAIS was performed. The femoral neck-shaft angle, femoral version, magnitude and clock-face location of the alpha angle, midcoronal center-edge angle (CEA), midsagittal CEA, acetabular version, and McKibbin index were measured on computed tomography scans. Univariate and multivariate linear regression analyses determined which measurements correlated with hip ROM, including hip flexion as well as hip internal and external rotation with the hip in 90° of flexion.

RESULTS

Two hundred hips that met the inclusion and exclusion criteria during the eligibility period were included in the analysis. The mean age was 31.9 ±10.0 years, there were 145 female patients (72%), and the mean body mass index was 25.2 ± 5.0. Multivariate linear regression analysis showed that the midsagittal CEA was the only measurement correlating with flexion (q = .031) whereas the femoral neck-shaft angle and McKibbin index were the only significant variables that correlated with external rotation (q = .031 and q < .001, respectively). Finally, the McKibbin index and maximum alpha angle were the only variables that correlated with internal rotation (q < .001 and q = .034, respectively).

CONCLUSIONS

Multivariate analysis showed that combined acetabular and femoral version significantly correlated with internal and external rotation whereas femoral version in isolation did not. Increased cam morphology remained a significant contributor to reduced internal rotation but did not affect hip flexion. These data suggest that hip ROM is affected by both femoral pathomorphology and acetabular pathomorphology and that careful evaluation of both should be conducted prior to corrective osteoplasty or osteotomy.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Increased femoral anteversion-related biomechanical abnormalities: lower extremity function, falling frequencies, and fatigue

BACKGROUND

Increased femoral anteversion (IFA) is defined as forwardly rotated femoral head relative to the transcondylar knee axis which may have a potential to reduce the functional quality of adolescents. Therefore, the aim of our study was to investigate the effects of IFA on lower-extremity function, falling frequency, and fatigue onset in neurologically intact children.

RESEARCH QUESTION

Does increased femoral anteversion influence lower extremity function, falling frequency and fatigue on set in healthy children?

METHODS

Sixty-five participants with increased femoral anteversion (IFA) and thirty-two healthy peers as control were included into the study. For the function, the lower extremity function form (LEFF) which is adapted from Lower Extremity Function Test used. Falling frequency and fatigue onset time were assessed by a Likert-type scale. In addition, the activities which cause frequently fall for the participants were questioned.

RESULTS

Lower extremity function was found deteriorated (p= 0.02) and falling frequency was higher (p = 0.00) in IFA than in controls. Fatigue onset time was not different between groups, although lower extremity function was strongly correlated with fatigue onset (rho = -0.537, p < 0.001). IFA children fall four times more during running (60%), three times more during fast walking (21.42%) than their healthy peers (14.28%, 7.14% respectively).

SIGNIFICANCE

IFA leads functional problems, especially in the form of high falling frequencies. According to the LEFF score, the most difficult functional parameters for these children were walking long distances, becoming tired, walking more than a mile, and standing on one spot. Also, shorter fatigue onset time may worsen the lower-extremity function secondarily. Because of the higher frequency of falling and functional problems, children with IFA may be more defenseless to injuries, especially in high-motor-skill activities such as running and soccer.