Variation in femoral anteversion in patients requiring total hip replacement

Femoral Neck Anteversion: Which Distal Femur Landmark Matters?

Background

Femoral neck anteversion has traditionally been measured by the angle between the distal femur posterior condylar axis (PCA) and a line drawn through the center of the femoral head and neck. While less common, the transepicondylar axis (TEA) has also been used to reference femoral neck anteversion. The purpose of this study was to compare femoral neck version of the PCA vs the TEA using computerized tomography (CT).

Methods

A total of 1507 femoral CTs were included. Precise bony landmarks were established: lateral epicondyle, medial epicondyle, posteromedial condyle, posterolateral condyle, center of the femoral neck, and center of the femoral head. Femoral version was calculated between the head and neck axis and either the PCA or TEA. Differences between sex and ethnicity were evaluated.

Results

The mean femoral anteversion was 12.7° ± 9.1° based on the PCA and 11.5° ± 7.9° based on the TEA (mean difference 1.2° ± 1.9°, P < .001). Males were less anteverted than females (9.8° ± 7.6° vs 13.5° ± 7.8°, P < .001). African Americans had less anteversion than other groups (8.1° ± 9.2° vs 11.5° ± 7.8°, P = .04), while Asians were more anteverted than other groups (12.1° ± 9.0° vs 11.2° ± 7.3°, P = .04). These values were referenced on the TEA.

Conclusions

In this series of over 1500 femoral CT scans, the mean difference between anteversion measurements referencing the PCA and TEA was 1.2°. Native femoral version varied widely between gender and ethnic groups. Extreme femoral version, defined as <0° or >30°, was present in 11.8% of patients referencing the PCA.

The Relationship Between Pelvic Tilt and Clinical Outcomes After Hip Preservation Surgery in Femoroacetabular Impingement Syndrome and Hip Dysplasia

Pelvic tilt is thought to be a compensatory mechanism in hip pathology, specifically in patients with femoroacetabular impingement syndrome (FAIS) and hip dysplasia. This study investigated the relationship between preoperative pelvic tilt and postoperative outcomes in patients undergoing hip preservation surgery for FAIS or hip dysplasia. We reviewed a prospective hip preservation database for demographic, radiographic, and outcome data for 89 patients who underwent hip preservation surgery with a primary diagnosis of FAIS or dysplasia from 2016 to 2020. Pelvic tilt was assessed on the standing anteroposterior radiograph with the pubic symphysis to sacroiliac joint (PS-SI) distance measurement. The International Hip Outcome Tool 12 (iHOT-12), Hip Outcome Score, Harris Hip Score, UCLA activity score, and European Quality of Life-Visual Analog Scale were used to assess hip function and pain preoperatively and postoperatively. The mean pelvic tilt (PS-SI distance) was 86.4±18.3 mm for the FAIS group and 96.2±15.1 mm for the dysplasia group. The statistical analysis demonstrated a positive relationship between pelvic tilt and change in iHOT-12 score (rs=0.262, P=.019) for all 89 patients with hip pathology and, separately, a trend toward significance for the 42 patients with FAIS (rs=0.330, P=.056). No other significant relationships were observed. The improvement in iHOT-12 score was greater for patients with more anterior tilt and less for patients with posterior pelvic tilt, regardless of underlying hip etiology. These results provide intriguing insights into an initial investigation on pelvic tilt in patients undergoing hip preservation surgery. Further investigation is necessary to assess pelvic tilt preoperatively and postoperatively, spinal parameters, and longer-term outcomes. [Orthopedics. 2023;46(6):e341-e346.].

Influence of femoral anteversion angle and neck-shaft angle on muscle forces and joint loading during walking

Femoral deformities, e.g. increased or decreased femoral anteversion (AVA) and neck-shaft angle (NSA), can lead to pathological gait patterns, altered joint loads, and degenerative joint diseases. The mechanism how femoral geometry influences muscle forces and joint load during walking is still not fully understood. The objective of our study was to investigate the influence of femoral AVA and NSA on muscle forces and joint loads during walking. We conducted a comprehensive musculoskeletal modelling study based on three-dimensional motion capture data of a healthy person with a typical gait pattern. We created 25 musculoskeletal models with a variety of NSA (93°-153°) and AVA (-12°-48°). For each model we calculated moment arms, muscle forces, muscle moments, co-contraction indices and joint loads using OpenSim. Multiple regression analyses were used to predict muscle activations, muscle moments, co-contraction indices, and joint contact forces based on the femoral geometry. We found a significant increase in co-contraction of hip and knee joint spanning muscles in models with increasing AVA and NSA, which led to a substantial increase in hip and knee joint contact forces. Decreased AVA and NSA had a minor impact on muscle and joint contact forces. Large AVA lead to increases in both knee and hip contact forces. Large NSA (153°) combined with large AVA (48°) led to increases in hip joint contact forces by five times body weight. Low NSA (108° and 93°) combined with large AVA (48°) led to two-fold increases in the second peak of the knee contact forces. Increased joint contact forces in models with increased AVA and NSA were linked to changes in hip muscle moment arms and compensatory increases in hip and knee muscle forces. Knowing the influence of femoral geometry on muscle forces and joint loads can help clinicians to improve treatment strategies in patients with femoral deformities.

Digital measurement and clinical significance of proximal femur in the older people of Inner Mongolia population, China

OBJECTIVE

This study aimed to measure the parameters of the proximal femur in the older people of Inner Mongolia, China and understand the influence of age and gender so as to provide guidance for the design and improvement of prosthesis for total hip arthroplasty.

METHODS

A total of 236 patients who underwent CT angiography of lower limbs in the Department of Imaging, Affiliated Hospital of Inner Mongolia Medical University of China were collected. They were divided into 4 groups according to age: < 60 (group A), 60-69 (group B), 70-79 (group C), and > 80 years (group D). Four anatomical parameters, including femoral head diameter (FHD), femoral neck-shaft angle (FNSA), femoral offset (FO), femoral neck anteversion (FNA), were measured by Mimics 21.0. Comparisons were made between age groups of the same gender and between genders in the same age group to analyze the correlation of the 4 parameters of proximal femur with age and gender. In addition, the results of this study were compared with previous studies.

RESULTS

There were no significant differences in FHD and FO between age groups, indicating no correlation with age. FNSA and FNA were no significantly different between group C and group D in the same gender, whereas there were significant differences between other age groups and were negatively correlated with age. There were significant differences in FHD and FO between genders in the same age group, with the males being larger than the females. FNSA and FNA were no significant differences between genders in the same age group.

CONCLUSIONS

FNSA and FNA decrease with age. FHD and FO were larger in males than in females in all age groups. Age and gender should be considered in the design of prosthesis.

Acetabular, Femoral, and Combined Anteversion in a Province in South Korea: Computed Tomography-Based Study

Background

The purpose of this study was to investigate the femoral, acetabular, and combined anteversion of the hip joint in South Koreans using computed tomography (CT).

Methods

We measured anteversion using CT venograms taken from 2016 to 2020. Of the total 1,073 patients, 952 patients were included in the study except for those with pelvic fractures, previous femoral fractures, childhood hip joint disease, osteoarthritis, or hip dysplasia (lateral center-edge angle, < 20), foreigners, and hip and knee replacement patients. Measurements were taken twice by two orthopedic surgeons.

Results

The femoral anteversion in women was 10.64° ± 10.26° (≤ 49 years), 15.75° ± 9.40° (50-59 years), 10.81° ± 9.14° (60-69 years), 12.38° ± 8.55° (70-79 years), and 11.23° ± 8.44° (≥ 80 years). The femoral anteversion in men was 12.02° ± 11.38° (≤ 49 years), 10.62° ± 9.11° (50-59 years), 6.09° ± 9.95° (60-69 years), 6.57° ± 9.51° (70-79 years), and 5.53° ± 9.29° (≥ 80 years). The acetabular anteversion in women was 17.65° ± 6.58° (≤ 49 years), 19.24° ± 6.42° (50-59 years), 20.30° ± 6.25° (60-69 years), 22.38° ± 7.36° (70-79 years), and 23.34° ± 6.98° (≥ 80 years). The acetabular anteversion in men was 15.21° ± 8.14° (≤ 49 years), 17.68° ± 6.00° (50-59 years), 17.54° ± 5.93° (60-69 years), 18.68° ± 6.62° (70-79 years), and 18.19° ± 6.94° (≥ 80 years). The combined anteversion in women was 28.29° ± 14.30° (≤ 49 years), 34.99° ± 10.62° (50-59 years), 31.11° ± 11.52° (60-69 years), 34.76° ± 10.86° (70-79 years), and 34.57° ± 11.45° (≥ 80 years). The combined anteversion in men was 27.23° ± 15.11° (≤ 49 years), 28.30° ± 11.23° (50-59 years), 23.63° ± 11.77° (60-69 years), 25.25° ± 12.02° (70-79 years), and 23.72° ± 11.88° (≥ 80 years).

Conclusions

Femoral anteversion tended to decrease with age in men and acetabular anteversion tended to increase in both men and women. Combined anteversion showed a tendency to increase slightly in women.

Does Individualization of Cup Position Affect Prosthetic or Bone Impingement Following THA?

INTRODUCTION

Spinopelvic (SP) mobility patterns during postural changes affect three-dimensional acetabular component position, the incidence of prosthetic impingement, and total hip arthroplasty (THA) instability. Surgeons have commonly placed the acetabular component in a similar "safe zone" for most patients. Our purpose was to determine the incidence of bone and prosthetic impingement with various cup orientations and determine if a preoperative SP analysis with individualized cup orientation lessens impingement.

METHODS

A preoperative SP evaluation of 78 THA subjects was performed. Data was analyzed using a software program to determine the prevalence of prosthetic and bone impingement with a patient individualized cup orientation versus six commonly selected cup orientations. Impingement was correlated with known SP risk factors for dislocation.

RESULTS

Prosthetic impingement was least with the individualized choice of cup position (9%) vs. preselected cup positions (18 to 61%). The presence of bone impingement (33%) was similar in all groups and not affected by cup position. Factors associated with impingement in flexion were age, lumbar flexion, pelvic tilt (stand to flexed seated), and functional femoral stem anteversion. Risk factors in extension included standing pelvic tilt, standing SP tilt, lumbar flexion, pelvic rotation (supine to stand and stand to flexed seated), and functional femoral stem anteversion.

CONCLUSION

Prosthetic impingement is reduced with individualized cup positioning based on SP mobility patterns. Bone impingement occurred in one-third of patients and is a noteworthy consideration in preoperative THA planning. Known SP risk factors for THA instability correlated with the It dependspresence of prosthetic impingement in both flexion and extension.

The effect of patient positioning on measurements of bone mineral density of the proximal femur: a simulation study using computed tomographic images

The patient's position may affect the bone mineral density (BMD) measurements; however, the extent of this effect is undefined. This CT image-based simulation study quantified changes in BMD induced by hip flexion, adduction, and rotations to recommend appropriate patient positioning when acquiring dual-energy x-ray absorptiometry images.

PURPOSE

Several studies have analyzed the effect of hip rotation on the measurement of bone mineral density (BMD) of the proximal femur by dual-energy x-ray absorptiometry (DXA). However, as the effects of hip flexion and abduction on BMD measurements remain uncertain, a computational simulation study using CT images was performed in this study.

METHODS

Hip CT images of 120 patients (33 men and 87 women; mean age, 82.1 ± 9.4 years) were used for analysis. Digitally reconstructed radiographs of the proximal femur region were generated from CT images to calculate the BMD of the proximal femur region. BMD at the neutral position was quantified, and the percent changes in BMD when hip internal rotation was altered from -30° to 15°, when hip flexion was altered from 0° to 30°, and when hip abduction was altered from -15° to 30° were quantified. Analyses were automatically performed with a 1° increment in each direction using computer programming.

RESULTS

The alteration of hip angles in each direction affected BMD measurements, with the largest changes found for hip flexion (maximum change of 17.7% at 30° flexion) and the smallest changes found for hip rotation (maximum change of 2.2% at 15° internal rotation). The BMD measurements increased by 0.34% for each 1° of hip abduction, and the maximum change was 12.3% at 30° abduction.

CONCLUSION

This simulation study quantified the amount of BMD change induced by altering the hip position. Based on these results, we recommend that patients be positioned carefully when acquiring DXA images.

Morphometric analysis of the lateral column of the distal humerus with an interest on radio-capitellar arthroplasty design. A computed tomography anatomical study on 50 elbows

PURPOSE

To perform a morphometric analysis of the distal humerus lateral column medullary canal (LCMC).

METHODS

Fifty computed tomography(CTs) from 24 males and 26 females were examined. Two observers measured: (1) the capitellum sagittal (R_S) and axial (R_T) radii of curvature; (2) the sagittal(Sd) and coronal(Cd) diameters of the LCMC in 5 different disto-proximal sites spaced 4 mm apart; (3) the capitellum and LCMC axis offsets on the sagittal (capSO,axSO) and coronal (capCO,axCO) planes; (4) the sagittal (Si) and coronal (Ci) inclination of the LCMC axis.

RESULTS

The mean R_S and R_T were 1.07 cm (SD, 0.11) and 1.30 cm (SD, 0.11), respectively. The mean Sd and Cd values were 1.17 cm (SD, 0.17) and 1.58 cm (SD, 0.24), respectively, with a disto-proximal decrease on both planes. The capSO, capCO, axSO and axCO mean values were 0.76 (SD, 0.21), 1.60 (SD, 0.27), - 0.16 (SD, 0.30) and 0.79 cm (SD, 0.30), respectively. Si and Ci were 70° and 72°, respectively. A strong correlation (r = 0.78) was found between R_S and R_T and between adjacent levels of Sd and Cd. AxSO and axCO yielded a strong inverse correlation. Male patients showed higher values than female ones in all variables (p < 0.03). The intra-class correlation coefficient (ICC) was always > 0.9.

CONCLUSION

The dimensions of the LCMC decrease disto-proximally, with the coronal diameters being greater than the sagittal diameters, resembling a portion of an elliptic torus with an antero-medial concavity. The articular surface of the humeral capitellum is non-spherical, with two strongly correlated radii of curvature. The results of this study may be relevant to the stem design of radiocapitellar arthroplasty.

Age and Sex Influence the Use of Modular Femoral Components in Total Hip Arthroplasty Performed for Primary Osteoarthritis

The impact of age and sex on femoral component choices in modular total hip arthroplasty (THA) is still unknown. A regional arthroplasty registry was interrogated about a modular stem in THA performed for primary osteoarthritis, with the aims to assess the influence of age and sex on stems sizes and neck choices. A total of 6830 THAs were included: all THAs had a modular stem (with 15 necks and 27 combinations per side). Patients were stratified by age in decades and sex. Necks were grouped according to the type of correction. The percentage of larger stem sizes increased in males and in elder patients (p < 0.001). Standard necks were overrepresented in males aged 40-59 and underrepresented in males aged 70 or older (p < 0.001). Half of the necks provided other corrections than standard or offset, especially in males aged 40-49 and females aged 70 or older (p < 0.001). Offset necks were predominant in elder patients (p < 0.001). Version-correcting necks were prevalent in younger males and older females (p < 0.001). Varus necks were implanted in one-third of the cases. The four commonest necks showed age and sex specific patterns. In the registry, age and sex impacted stem size and neck choices in THA performed for primary osteoarthritis.

Achieving Target Cemented Femoral Stem Anteversion Using a 3-Dimensional Model

Background

Total hip arthroplasty aims to provide patients with a pain-free and stable hip joint through optimization of biomechanics such as femoral anteversion. There are studies evaluating the limits of cementless stem version, however, none assessing the range of version achieved by a cemented collarless stem. A computed tomography (CT)-based study was performed, utilizing a contemporary robotic planning platform to assess the amount of rotation afforded by a cemented collarless stem, whilst maintaining native biomechanics.

Methods

The study utilized 36 cadaveric hips. All had CT scans of the pelvis and hip joints. The CT scans were then loaded into a contemporary robotic planning platform. A stem that restored the patients native femoral offset was selected and positioned in the virtual femur. The stem was rotated while checking for cortical contact at the level of the neck cut. Cortical contact was regarded as the rotation limit, assessed in both anteversion and retroversion. Target range for stem anteversion was 10°-20°. Failure to achieve target version triggered a sequence of adjustments to simulate surgical decisions.

Results

Native femoral offset and target version range was obtained in 29 of 36 (80.5%) cases. Following an adjustment sequence, 4 further stems achieved target anteversion with a compromise in offset of 2.3 mm. Overall 33 of 36 (91.7%) stems achieved the target anteversion range of 10°-20°.

Conclusions

Target femoral stem anteversion can be achieved using a cemented, collarless stem in a CT-based 3-dimensional model in 80.5% of hips. With a small compromise in offset (mean 2.3 mm), this can be increased to 91.7%.

The Effect of Region of Interest on Measurement of Bone Mineral Density of the Proximal Femur: Simulation Analysis Using CT Images

While accurate measurement of bone mineral density (BMD) is essential in the diagnosis of osteoporosis and in evaluating the treatment of osteoporosis, it is unclear how region of interest (ROI) settings affect measurement of BMD at the total proximal femur region. In this study, we performed a simulation analysis to clarify the effect on BMD measurement of changing the ROI using hip computed tomography (CT) images of 75 females (mean age, 62.4 years). Digitally reconstructed radiographs of the proximal femur region were generated from CT images to calculate the change in BMD when the proximal boundary of the ROI was altered by 0-10 mm, and when the distal boundary of the ROI was altered by 0-30 mm. Further, changes in BMD were compared across BMD classification groups. A mean BMD increase of 0.62% was found for each 1-mm extension of the distal boundary. A mean BMD decrease of 0.18% was found for each 1-mm alteration of the proximal boundary. Comparing BMD classification groups, patients with osteoporosis and osteopenia demonstrated greater BMD changes than patients with normal BMD for the distal boundary (0.68%, 0.64%, and 0.54%, respectively) and patients with osteoporosis demonstrated greater BMD changes than patients with osteoporosis and normal BMD for the proximal boundary (0.37%, 0.13%, and 0.03%, respectively). In conclusion, our study found that a consistent ROI setting, especially on the distal boundary, is necessary for the accurate measurement of total proximal femur BMD. Based on the findings, we recommend confirming that the ROI setting shown on the BMD result form is consistent with changes in serial BMD.

Functional Femoral Anteversion: Axial Rotation of the Femur and its Implications for Stem Version Targets in Total Hip Arthroplasty

Background

Acetabular and femoral component positioning are important considerations in reducing adverse outcomes after total hip arthroplasty (THA). Previous assessments of femoral anteversion examined anatomic femoral anteversion (AFA) referenced to anatomic landmarks. However, this does not provide a functional understanding of the femur's relationship to the hip. We investigate a new measurement, functional femoral anteversion (FFA), and sought to measure its variability across a large sample of patients undergoing THA.

Methods

A total of 1008 consecutive patients underwent THA surgery between September 2019 and July 2021. All patients were measured for supine and standing functional femoral rotation (FFR), AFA, and FFA.

Results

The mean standing FFA was 13.2° ± 12.2° (-27.8° to 52.3°). The mean change in FFR from supine to standing was -2.2° ± 11.8° (-43.0° to 41.9°). Of all, 161 (16%) patients had standing FFA version greater than 25°. Four hundred sixty (46%) patients had standing FFR (internal or external) greater than 10°. One hundred twenty-three (12%) patients exhibited an increase in external rotation from supine to standing of greater than 10°. A moderate, negative linear relationship was observed between AFA and standing external femoral rotation (P <<.001, R = -0.46), indicating people may externally rotate their femur as AFA decreases with age.

Conclusions

Functional alignment of the femur in patients requiring THA is understudied. It is now understood that the femur, like the pelvis, can rotate substantially between functional positions. Enhancing our understanding of FFA and FFR may improve both acetabular and femoral component positioning.

Abnormal Spinopelvic Motion and Spine Deformity are Associated With Native Femoral Retroversion in the Setting of Total Hip Arthroplasty

Background

The effect of spinopelvic pathology on femoral version is unclear. This study investigated variability in native femoral anteversion in patients undergoing total hip arthroplasty (THA) and its relationship to the patient’s underlying spinopelvic pattern.

Methods

A retrospective chart review was performed to include in the study all patients undergoing robot-assisted THA over a 3-year period. Native femoral version was measured for each patient using a preoperative computed tomography scan and categorized as excessive, normal, or retroverted. Additionally, a subset analysis was performed for all patients with sit-to-stand dynamic pelvic radiographs available, and cases were classified by spinopelvic pattern.

Results

A total of 119 patients were included in the study with a mean age of 68.6 years; 61 (51%) were female. The median femoral anteversion for the entire study group was 6.0° (−32° to 40°, interquartile range 13.5°). Eleven patients (9.2%) had excessive femoral anteversion, 54 of the 119 (45.4%) had normal femoral version, and 54 of the 119 (45.4%) had native retroversion. Forty-two patients (35.3%) had sit-to-stand radiographs available and were subclassified by femoral version type and spinopelvic parameters. Welch’s analysis of variance demonstrated a significant difference in femoral version among spinopelvic patterns (F = 7.826, P = .003), with Games-Howell post hoc analysis showing increased retroversion in deformity-stiff patients compared to deformity-normal mobility patients (P = .003).

Conclusions

This study demonstrates that native femoral retroversion is present in a significant number of patients undergoing THA and is more common in patients with stiff spine deformities. Based on this observation, currently available spinopelvic classification systems should be modified to account for native femoral version.

Does surgery change pelvic tilt? : an investigation in patients with osteoarthritis of the hip, dysplasia, and femoroacetabular impingement

AIMS

Pelvic tilt is believed to affect the symptomology of osteoarthritis (OA) of the hip by alterations in joint movement, dysplasia of the hip by modification of acetabular cover, and femoroacetabular impingement by influencing the impingement-free range of motion. While the apparent role of pelvic tilt in hip pathology has been reported, the exact effects of many forms of treatment on pelvic tilt are unknown. The primary aim of this study was to investigate the effects of surgery on pelvic tilt in these three groups of patients.

METHODS

The demographic, radiological, and outcome data for all patients operated on by the senior author between October 2016 and January 2020 were identified from a prospective registry, and all those who underwent surgery with a primary diagnosis of OA, dysplasia, or femoroacetabular impingement were considered for inclusion. Pelvic tilt was assessed on anteroposterior (AP) standing radiographs using the pre- and postoperative pubic symphysis to sacroiliac joint (PS-SI) distance, and the outcomes were assessed with the Hip Outcome Score (HOS), International Hip Outcome Tool (iHOT-12), and Harris Hip Score (HHS).

RESULTS

The linear regression model revealed a significant negative predictive association between the standing pre- and postoperative PS-SI distances for all three groups of patients (all p < 0.001). There was a significant improvement in all three outcome measures between the pre- and postoperative values (p < 0.05).

CONCLUSION

There is a statistically significant decrease in pelvic tilt after surgery in patients with OA of the hip, dysplasia, and femoroacetabular impingement. These results confirm that surgery significantly alters the pelvic orientation. Pelvic tilt significantly decreased after total hip arthroplasty, periacetabular osteotomy, and arthroscopy/surgical hip dislocation. The impact of surgery on pelvic tilt should be considered within the therapeutic plan in order to optimize pelvic orientation in these patients.Cite this article: Bone Joint J 2022;104-B(9):1025-1031.

Factors influencing the outcomes of minimally invasive total hip arthroplasty: a systematic review

Introduction

The present systematic review investigated possible factors which may influence the surgical outcome of minimally invasive surgery for total hip arthroplasty (MIS THA).

Methods

In January 2022, the Embase, Google Scholar, PubMed, and Scopus databases were accessed. All the clinical trials investigating the clinical outcome of MIS THA were considered.

Results

Data from 9486 procedures were collected. Older age was moderately associated with greater Visual Analogue Scale (VAS) (P = 0.02) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) (P = 0.009) at last follow-up, and shorter surgical duration (P = 0.01). Greater body mass index (BMI) at baseline was moderately associated with greater cup anteversion (P = 0.0009), Oxford Hip Score (OHS) at last follow-up (P = 0.04), longer surgical duration (P = 0.04), increased leg length discrepancy (P = 0.02), and greater rate of infection (P = 0.04). Greater VAS at baseline was weakly associated with greater VAS at last follow-up (P < 0.0001), total estimated blood lost (P = 0.01), and lower value of Harris Hip Score (HHS) (P = 0.0005). Greater OHS at baseline was associated with greater post-operative VAS (P = 0.01). Greater WOMAC at baseline was associated with lower cup anteversion (P = 0.009) and greater VAS (P = 0.02). Greater HHS at baseline was associated with shorter hospitalisation (P = 0.001).

Conclusion

Older age and greater BMI may represent negative prognostic factors for MIS THA. The clinical outcome is strongly influenced by the preoperative status of patients.

Proximal Femoral Rotational Osteotomy for Symptomatic Femoral Retroversion : A Case Report

The Rotational osteotomy for femoral retroversion has been extremely rare despite the known association between femoral neck retroversion, hip pain, and osteoarthritis. Here, we describe a case of femoral neck retroversion for which proximal femoral rotation osteotomy. A 16-year-old boy with a past history of developmental dysplasia of the both hip treated conservatively presented with a complaint of pain in left hips. On physical examination, flexion of the left hip was limited to 90° with terminal pain. Internal rotation was also limited to 10°. Computed tomography (CT) showed -7.1° anteversion of the left femur. We performed rotational osteotomy to increase femoral anteversion because conservative treatment was not effective. The postoperative course was uneventful. At 12 postoperative months, his left hip pain was completely disappeared and femoral anteversion was 34° on CT scans. Retroversion of the femur is a distinct dynamic factor that should be considered in the evaluation of mechanical causes of hip pain. Restoring the normal rotational alignment of the hip resulted in cure of the impingement due to femoral retroversion. J. Med. Invest. 67 : 214-216, February, 2020.

Accuracy of CT for measuring femoral neck anteversion in children with developmental dislocation of the hip verified using 3D printing technology

Background

Accurate femoral neck anteversion angle (FNA) measurement is of great significance in the diagnosis and treatment of developmental dysplasia of the hip (DDH) in children. The FNA measurement still remains a controversy. We aimed to verify the accuracy of our CT method by 3D printing technology and to evaluate its clinical value.

Methods

Sixty-eight children with unilateral DDH were enrolled, and their FNA was measured using 2D-CT and 3D-CT, respectively, by three observers. This procedure was repeated 3 months later. The above measurement outcomes were then compared with the results in the 3D-printed femur (3D-PF) model. The FNA in the 3D-PF model was measured by three observers (two radiologists and one orthopedist; all were professors) collectively through electronic angle instrument.

Results

The primary measurement of FNA at the affected hips by 2D-CT was 44.0 ± 6.1, 49.5 ± 8.9, and 52.8 ± 7.9°, respectively. On the 3D-CT, it was 47.6 ± 5.4, 49.3 ± 6.8, and 48.6 ± 6.2°. Three months later, the FNA on 2D-CT was 49.3 ± 10.5, 42.8 ± 7.4, and 45.1 ± 9.3°, and it was 48.0 ± 6.5, 48.9 ± 7.2, and 49.0 ± 5.7° on 3D-CT, respectively. The FNA in the 3D-PF model at the affected and unaffected hips was 48.5 ± 6.6 and 36.9 ± 13.1°. There were significant differences between 2D-CT and 3D-PF measurements, but no significant difference was found between 3D-CT and 3D-PF measurements. The results by 2D-CT showed significant differences among groups and between the groups. However, the results by 3D-CT had no significant differences among groups or between the groups.

Conclusion

The results of our study showed that 3D-CT is a more precise, and reproducible method for FNA measurement in DDH. The FNA at the affected hips is 11.6° larger than the unaffected in DDH children aged 3–8 years.

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.