Side-to-side variability in the femoral neck anteversion angle: A study of the Japanese population with osteonecrosis of the femoral head.

BACKGROUND: Side-to-side variability in the femoral neck anteversion angle (FA) reportedly varies from 0.0° to 17.3°. To investigate the side-to-side variability in the FA and the relationship between the FA and the morphology of the acetabulum in the Japanese population, we performed a three-dimensional computed tomography (CT)-based study involving patients with osteonecrosis of the femoral head (ONFH). METHODS: CT data were obtained from 170 nondysplastic hips of 85 patients with ONFH. The FA and acetabular coverage parameters, including the acetabular anteversion angle, acetabular inclination angle, and acetabular sector angle in the anterior, superior, and posterior directions, were measured using three-dimensional CT. The distribution of the side-to-side variability in the FA was evaluated separately for each of the five degrees. RESULTS: The mean side-to-side variability in the FA was 6.7° ± 5.3° (range, 0.2°-26.2°). The distribution of the side-to-side variability in the FA was 0.0°-5.0° in 41 patients (48.2%), 5.1°-10.0° in 25 patients (29.4%), 10.1°-15.0° in 13 patients (15.3%), 15.1°-20.0° in 4 patients (4.7%), and >20.1° in 2 patients (2.4%). There was a weak negative correlation between the FA and anterior acetabular sector angle (r = -0.282, P < 0.001) and a very weak positive correlation between the FA and acetabular anteversion angle (r = 0.181, P < 0.018). CONCLUSIONS: The mean side-to-side variability in the FA was 6.7° ± 5.3° (range, 0.2°-26.2°) in Japanese nondysplastic hips, and about 20% of the patients had a side-to-side variability of >10°.

Distribution and outliers of anteversion of short-length cementless stem.

INTRODUCTION: Inadequate stem version might lead to impingement and instability after cementless total hip arthroplasty (THA). We evaluated (1) the distribution of short-stem anteversion, (2) the proportion of stems with an anteversion less than 5° or larger than 25°, (3) combined cup and stem anteversion, and (4) dislocation rate. MATERIALS AND METHODS: We evaluated the native femoral anteversion and stem anteversion in 340 patients (340 THAs): 144 men and 196 women. Their mean age was 56.2 (22-87) years and mean body mass index was 25.1 (15.2-40.7) kg/m2. The femoral neck anteversion was measured on pre-operative CT scan and the stem anteversion was obtained during the operation. The safe zone of the stem anteversion was defined as 5 to 25°. RESULTS: The femoral neck anteversion ranged from -15 to 61° (mean, 15.0°; SD, ±10.6°). The stem anteversion ranged -7 to 50° (mean, 15.7°; SD, ±9.5°). It was optimal (5-25°) in 71.2% (242/340), insufficient (<5°) in 13.3% (45/340), and excessive (>25°) in 15.6% (53/340). The stem anteversion had a medium correlation with the femoral neck anteversion (correlation coefficient = 0.449). The combined anteversion was 42.0° (range, 35.2-52.3°; SD, ±2.8°). During two to four year follow-up, no hip dislocated. CONCLUSIONS: Short-length stem had a great variability in the anteversion and considerable portion (28.9%, 98/340) of stems had an anteversion outside the safe zone. Surgeons should be aware of this variability of stem anteversion to compensate for abnormal stem anteversion, which might lead to impingement and instability after THA.

Geometrical restoration during total hip arthroplasty is related to change in gait pattern - a study based on computed tomography and three-dimensional gait analysis.

BACKGROUND: The effect of change in hip anatomy on change in gait pattern is not well described in current literature. Therefore, our primary aim was to describe and quantify changes in hip geometry and gait pattern 1 year after total hip arthroplasty (THA) in individuals with hip osteoarthritis. Our secondary aim was to explore the effect of postoperative change in femoral neck anteversion (FNA) and femoral offset and acetabular offset (FO/AO) quota on postoperative change in hip rotation and hip adduction moment during gait, respectively, 1 year after THA". METHODS: Sixty-five individuals with primary hip osteoarthritis, scheduled for THA, were analyzed in this prospective intervention study. Participants were evaluated pre- and 1 year postoperatively with computed tomography-scans, three-dimensional gait analysis, and patient-reported outcome measures. Multiple linear regressions were performed to evaluate the association between change in joint anatomy and change in gait pattern after THA. RESULTS: One year postoperatively, global offset was symmetrical between sides as a result of decreased acetabular offset and increased femoral offset on the operated side. Quality of overall gait pattern improved, and participants walked faster and with less trunk lean over the affected side. FNA and hip rotations during walking changed equally in external and internal directions after THA and change in hip rotation during walking was associated with change in FNA in the same direction. An increase in external hip adduction moments was, on the other hand, not associated with change in FO/AO quota but with a more upright walking position and increased walking speed. CONCLUSIONS: The findings of this study suggest that geometrical restoration during THA impacts postoperative gait pattern and, in addition to known factors such as FO, height of hip rotation center, and leg length discrepancy, the FNA must also be taken into consideration. TRIAL REGISTRATION: Trial registration: Clinicaltrial.gov , NCT01512550 , Registered 19 January 2012 - Retrospectively registered.

Tibiofemoral rotation is related to differences in the lateral femoral condyle configuration in both normal subjects and women with hip dysplasia: a three-dimensional analysis.

BACKGROUND: We assessed the morphological differences in the knee joint related to knee rotation angle in patients with hip dysplasia. These results may explain the anatomy of the knee in patients with hip dysplasia and aid in planning knee surgery. METHODS: We enrolled 73 women (146 legs, 35.6 ± 9.0 years) with bilateral hip dysplasia and 45 healthy women (90 legs, 49.0 ± 18.9 years) without lumbago, knee symptoms, or osteoarthritic findings of the knee or spine on plain radiographs. We examined the parameters affecting knee rotation angle, such as the condylar twist angle and femoral condyle measurements with a three-dimensional bone model using the correlation coefficients of each parameter. RESULTS: The condylar twist angle and the length of the posterior part of the lateral femoral condyle were statistically positively correlated with knee rotation angle in both the normal (condylar twist angle: r = 0.286, p = 0.007, posterolateral: r = 0.429, p < 0.001) and developmental dysplasia of the hip groups (condylar twist angle: r = 0.230, p = 0.033, posterolateral: r = 0.272, p = 0.005). Knee rotation angle had no statistical correlation with femoral neck anteversion in the developmental dysplasia of the hip group (r = 0.094, p = 0.264), but had a statistical correlation with femoral neck anteversion in the normal group (r = 0.243, p = 0.039). CONCLUSIONS: Knee joint morphology is affected by hip dysplasia. We found that the length of the posterior part of the lateral femoral condyle was significantly positively correlated with knee rotation angle in both the normal and developmental dysplasia of the hip groups, and this finding indicates that a greater posterolateral dimension was associated with a greater knee rotation angle. These morphological knee joint differences in patients with hip dysplasia may help determine the alignment of prostheses in total knee arthroplasty.

The consistency between measurements of the femoral neck anteversion angle in DDH on three-dimensional CT and MRI.

BACKGROUND: Three-dimensional computed tomography (3D CT) has been regarded by some investigators as the gold standard for measurements of the femoral neck anteversion angle (FNA) in developmental dysplasia of the hip (DDH), although a simple and reliable imaging method using a non-ionizing technique is needed. PURPOSE: To determine the consistency between measurements of the FNA in DDH using 3D CT and magnetic resonance imaging (MRI) and to estimate the precision, reliability, and reproducibility of MRI for the measurement of the FNA and assess whether MRI could replace 3D CT. MATERIAL AND METHODS: 3D CT and MRI were used to measure the FNA in 22 patients, including 18 girls and four boys, with a mean age of 3 years (age range, 1-7 years). All of the measurements were performed independently by two radiologists at different times. This exercise was repeated 2 weeks later by one of the radiologists. RESULTS: High consistency was found between the MRI and 3D CT measurements (intraclass correlation coefficient [ICC] of 0.906, P < 0.05). The mean inter-observer and intra-observer agreements were high for MRI (ICC = 0.948 and 0.964, respectively, P < 0.05 for both) and for 3D CT (ICC = 0.942 and 0.966, respectively, P < 0.05 for both). CONCLUSION: Compared with 3D CT, MRI provided a precise, reliable and reproducible method of measuring the FNA in DDH. MRI is recommended as an appropriate technique for measurement of the FNA in DDH, and this approach could replace 3D CT because it delivers no ionizing radiation and offers a better display of soft tissue pathological changes.

Mechanical effect of changed femoral neck ante-version angles on the stability of an intertrochanteric fracture fixed with PFNA: A finite element analysis.

Objective: Change of femoral neck ante-version angle postoperatively due to inadequate reduction could result in unsatisfying treatment outcome of intertrochanteric fracture. However, the influence of increased or decreased femoral neck ante-version on the biomechanical stability of the bone-implant complex has rarely been studied. Methods: A finite element model of a complete normal human femur with normal femoral neck ante-version as 13° was established accurately by scanning a 64 year old female femur. The models of 31-A1.1 intertrochanteric fractures with different femoral neck ante-version angles of 3°, 5.5°, 8°, 10.5°, 13°, 15.5°, 18°, 20.5°, 23° were created. They were assembled with a proximal femoral nail anti-rotation (PFNA) device. The biomechanical differences with varying femoral neck ante-version angles were compared using finite element analysis method. Results: As the femoral neck ante-version angle gradually increased from 13° to 23°with a gradient of 2.5°, the peak von Mises stress was gradually increased from 137.82 MPa to 276.02 MPa. Similarly, the peak von Mises stress was gradually increased from 137.82 MPa to 360.12 MPa with the femoral neck ante-version angle decreased from 13° to 3°. When decreased ante-version angle of 7.5° and increased ante-version angle of 10° will exceed the yield strength of femoral (240.32 MPa), the risk of femoral fracture will increase significantly. The maximum displacement of the femur was significantly reduced for increased ante-version models than for decreased ante-version models, whether the changes of ante-version angles were 2.5°, 5°, 7.5° or 10°. The maximum stress of PFNA was found in the intersection of main nail and helical blade, and became greater gradually as the ante-version angle increased or decreased with a gradient of 2.5°. The maximum stress of PFNA was presented in the model 5.5° with the maximum stress of 724.42 MPa (near to the yield strength of titanium alloy of 700-1000 MPa), producing the breakage risk of PFNA. The maximum displacement of the PFNA was significantly reduced for increased ante-version models than for decreased ante-version models, whether the changes of ante-version angles were 2.5°, 5°, 7.5° or 10°. Conclusion: Based on the results of present study, it was demonstrated that the anatomical reduction of femoral neck ante-version was vital to secure the optimal stability. Abnormal femoral ante-version could increase the potential risk of failure for intertrochanteric fracture after PFNA. The stability of increased femoral ante-version (less than 10°) was superior to the stability of decreased ante-version (less than 5°) for the cases of difficulty to acquire anatomical reduction. The clinical implication of the finding was that increased femoral neck ante-version had an advantage of mechanical stability towards the decreased femoral neck ante-version for the cases of comminuted intertrochanteric fracture and failure of anatomical reduction.

The effect of functional calibration methods on gait kinematics in adolescents with idiopathic rotational deformity of the femur.

BACKGROUND: Due to anatomical deviations, assumptions of the conventional calibration method for gait analysis may be violated in individuals with rotational deformities of the femur. Functional calibration methods were compared with conventional methods in this group for 1) localization of the hip joint center and orientation of the knee axis, and 2) gait kinematics. METHODS: Twenty-four adolescents with idiopathic rotational deformity of the femur underwent gait analysis and a CT scan. During standing, distance between hip joint centers and knee axis orientation were compared between calibration methods, with CT serving as reference for hip joint center estimation. Gait kinematics were compared using statistical parametric mapping. FINDINGS: The conventional calibration method estimated the hip joint center closer to the CT reference (4±12 mm more lateral) than the functional calibration method (26 ± 20 mm more lateral). Orientation of the knee joint axis was 2.6° less internal in the functional calibration method. During gait, statistical parametric mapping revealed significantly more hip flexion, less external hip rotation during the swing phase, less knee varus-valgus motion, and larger knee flexion angles when applying the functional method. INTERPRETATION: Functional calibration methods were less accurate in determining the hip joint center location than the conventional calibration method and resulted in a knee joint axis that was less internally rotated. Importantly, there was less knee joint angle crosstalk during gait when using the functional method. Although differences between methods on gait kinematics were within clinically acceptable limits for the sagittal plane, relatively larger differences on transversal hip kinematics may hold clinical importance.

[Analysis of factors associated with the influence of femoral stem anteversion after total hip arthroplasty].

Objective: To explore the related factors of femoral stem anteversion (FSA) after total hip arthroplasty (THA), so as to provide reference for clinical design of FSA before operation and reduce the risk of hip dislocation after arthroplasty. Methods: Ninty-three patients (103 hips) who underwent THA between October 2021 and September 2022 and met the selection criteria were selected as the study subjects. Among them, there were 48 males and 45 females with an average age of 58.5 years (range, 25-88 years). Body mass index was 18.00-37.84 kg/m 2, with an average of 24.92 kg/m 2. There were 51 cases (57 hips) of osteonecrosis of femoral head, 35 cases (39 hips) of hip osteoarthritis, and 7 cases (7 hips) of congenital hip dysplasia. Based on CT images, the following indicators were measured: preoperative femoral neck anteversion (FNA), preoperative femoral rotation angle (FRA), preoperative acetabular anteversion (AA), and preoperative combined anteversion (CA; the sum of preoperative FNA and AA); postoperative FSA and the change in femoral anteversion angle (the difference between postoperative FSA and preoperative FNA). Based on preoperative X-ray films, the following indicators were measured: femoral cortical thickness index (CTI) and canal flare index (CFI), the proximal femoral medullary cavity was classified according to Noble classification (champagne cup type, normal type, chimney type), neck-shaft angle (NSA), and femoral offset (FO). Pearson correlation analysis, one-way ANOVA, and Point-biserial correlation analysis were used to investigate the correlation between postoperative FSA, postoperative change in femoral anteversion angle, and patient diagnosis, proximal femoral medullary cavity anatomy type, gender, age, as well as preoperative FNA, FRA, AA, CA, NSA, FO, CTI, and CFI. FSA was used as the dependent variable and the independent variables that may be related to it were included for multiple linear regression analysis. Results: Based on CT image measurement, preoperative FNA was (15.96±10.01)°, FRA (3.36±10.87)°, AA (12.94±8.83)°, CA (28.9±12.6)°, postoperative FSA (16.18±11.01)°, and postoperative change in femoral anteversion angle was (0.22±9.98)°. Based on preoperative X-ray films measurements, the CTI was 0.586±0.081; the CFI was 4.135±1.125, with 23 hips classified as champagne cup type, 68 hips as normal type, and 12 hips as chimney type in the proximal femoral medullary cavity anatomy; NSA was (132.87±7.83)°; FO was (40.53±10.11) mm. There was no significant difference between preoperative FNA and postoperative FSA ( t=-0.227, P=0.821). Pearson correlation analysis showed that postoperative FSA was positively correlated with preoperative FNA, preoperative CA, postoperative change in femoral anteversion angle, and age ( P<0.05), while negatively correlated with preoperative FRA ( P<0.05). The postoperative change in femoral anteversion angle were positively correlated with preoperative FRA and postoperative FSA ( P<0.05), and negatively correlated with preoperative CA and FNA ( P<0.05). One-way ANOVA analysis showed that the above two indicators were not correlated with diagnosis and the proximal femoral medullary cavity anatomy type ( P>0.05). Multiple linear regression analysis showed a linear correlation between FSA and FNA, CA, age, and FRA ( F=10.998, P<0.001), and the best fit model was FSA=0.48×FNA-2.551. Conclusion: The factors related to FSA after THA include patient's age, preoperative FNA, CA, FRA and postoperative femoral anteversion, of which preoperative FNA is the most closely related. When designing a surgical plan before surgery, attention should be paid to the patient's preoperative FNA, and if necessary, CT around the hip joint should be scanned to gain a detailed understanding of the proximal femoral anatomical structure.

Effects of hindlimb suspension on development of proximal and distal femur morphological abnormalities in growing rats.

Although morphological abnormalities of the femur are known predisposing factors for numerous musculoskeletal disorders, the etiology of these abnormalities is poorly understood. This study aimed to investigate whether femoral morphogenesis is affected by hindlimb suspension (HS) in growing rats. We used 41 four-week-old female rats in this study. In the HS groups, rats were suspended from their tails for 2, 4, and 8 weeks. Age-matched animals were used as controls. We examined morphological indices of the femur using three-dimensional reconstructed images from X-ray computed tomography. The femoral neck anteversion angle (AVA) was higher with growth in the experimental groups and did not differ in control groups. The AVAs in the HS groups were larger than controls at any time point. In the control groups, the trochlear angle (TA) was higher, rotating inward with growth, but did not differ in the HS groups. The TAs in the HS groups were smaller and rotated more outward compared with the control groups at any time point. The height ratios of the medial and lateral condyles (MC/LC), an asymmetry index, were larger in the HS groups compared to controls at any time point. There were strong relationships between proximal (AVA) and distal morphologies, such as the TA (Spearman's coefficient [rs ] = -0.80, p < 0.001) and MC/LC (rs = 0.79, p < 0.001). Our data suggest that sufficient physical activity in early life may protect against morphological femur abnormalities associated with hip and knee joint diseases.

The impact of symptomatic femoral neck anteversion and tibial torsion on gait, function and participation in children and adolescents.

BACKGROUND: Torsional deformities of the lower limbs in children and adolescents are a common cause of in-toeing gait and cause gait deviations. The purpose of this study was to examine the relationship of children and adolescents with suspected Idiopathic Torsional Deformities (ITD) and pain, gait function, activity and participation. METHODS: A retrospective review of all children and adolescents who attended our Centre over a 5-year period for evaluation of the effect of ITD. All children completed three-dimensional gait analysis (3DGA), standardized physical examination, medical imaging and the Pediatric Outcomes Data Collection Instrument (PODCI). Statistical analysis was completed using two sample t-tests, Pearson's Correlation and linear regression. RESULTS: Fifty children and adolescents, 40 females and 10 males with a mean age of 13.5 years were included. Children reported a high prevalence of pain(86%), had increased internal hip rotation(p = 0.002) and decreased external hip rotation(p < 0.001) on physical examination when compared to published normative data. Medical imaging showed a mean(SD) femoral neck anteversion (FNA) of 38°(13°) and external tibial torsion of 39°(12°). Mean(SD) PODCI score was 32(16), indicating these children are functioning below their typically developing peers. The 3DGA kinematics show deviations from typical data including hip rotation, foot progression, pelvic tilt, hip flexion and knee extension. Observed mild kinetic deviations were within typical limits. The relationship between FNA and gait parameters, FNA and PODCI and gait and PODCI were weak. SIGNIFICANCE: These children and adolescents have altered gait and experience pain leading to impaired function and diminished participation. Therefore, ITD is not purely a cosmetic issue.

Variation in femoral anteversion in patients requiring total hip replacement.

BACKGROUND: Optimal implant alignment is important for total hip replacement (THR) longevity. Femoral stem anteversion is influenced by the native femoral anteversion. Knowing a patient's femoral morphology is therefore important when planning optimal THR alignment. We investigated variation in femoral anteversion across a patient population requiring THR. METHODS: Preoperatively, native femoral neck anteversion was measured from 3-dimensional CT reconstructions in 1215 patients. RESULTS: The median femoral anteversion was 14.4° (-27.1-54.5°, IQR 7.4-20.9°). There were significant gender differences (males 12.7°, females 16.0°; p < 0.0001). Femoral anteversion in males decreased significantly with increasing age. 14% of patients had extreme anteversion (<0° or >30°). CONCLUSIONS: This is the largest series investigating native femoral anteversion in a THR population. Patient variation was large and was similar to published findings of a non-THR population. Gender and age-related differences were observed. Native femoral anteversion is patient-specific and should be considered when planning THR.

[Measurement of femoral neck anteversion of developmental dislocation of hip in children by 3D printing technique].

OBJECTIVE: To explore the method and accuracy of measuring the femoral neck anteversion in children with developmental dislocation of the hip by using 3D printing technology, so as to find out the method of measuring the femoral neck anteversion accurately and guide the formulation of the operation plan. METHODS: From June 2016 to September 2018, 17 patients with unilateral developmental dislocation of the hip were enrolled in the study, including 2 males and 15 females, aged 2 to 13 (5.47±0.81) years old, 11 on the left and 6 on the right. The methods of CT, 3D printing and intraoperative anteversion of femoral neck were used to measure the anteversion of femoral neck respectively. The intraoperative measurement was used as the standard reference value forstatistical analysis, and the accuracy of the first two methods was compared. RESULTS: The average value of CT was (36.00±1.66)°, the average value of model method was(43.91±1.62)°, and the average value of intraoperative method was(44.21±1.62)°. There were significant differences in CT measurement, model measurement and intraoperative measurement(P<0.05). There was no significant difference between model method and intraoperative method (P>0.05). CONCLUSION: Compared with the traditional CT method, the 3D printing model method is simpler, more accurate and more repeatable, and can simulate the operation before operation. It is an ideal method to measure the femoral neck anteversion.

Pre- and postoperative offset and femoral neck version measurements and validation using 3D computed tomography in total hip arthroplasty.

BACKGROUND: Restoration of a correct biomechanical situation after total hip arthroplasty is important. PURPOSE: To evaluate proximal femoral symmetry of acetabular and femoral offset and femoral neck anteversion pre- and postoperatively in hip arthroplasty by semi-automated 3D-CT and to validate the software measurements by inter- and intraobserver agreement calculations. MATERIAL AND METHODS: In low-dose CT on 71 patients before and after unilateral total hip arthroplasty, two observers used a digital 3D templating software to measure acetabular offset, true and functional femoral offset, and femoral neck anteversion. Observer agreements were calculated using intraclass correlation. Hip measurements were compared in each patient and between pre- and postoperative measurements. RESULTS: Preoperatively, acetabular offset (2.4 mm), true (2.2 mm), and functional global offset (2.7 mm) were significantly larger on the osteoarthritic side without side-to-side differences for true and functional femoral offset or femoral neck anteversion. Postoperatively, acetabular offset was significantly smaller on the operated side (2.1 mm) with a concomitantly increased true (2.5 mm) and functional femoral offset (1.5 mm), resulting in symmetric true and functional global offsets. There were no differences in postoperative femoral neck anteversion. Inter- and intraobserver agreements were near-perfect, ranging between 0.92 and 0.98 with narrow confidence intervals (0.77-0.98 to 0.94-0.99). CONCLUSION: Acetabular and concomitantly global offset are generally increased in hip osteoarthritis. Postoperative acetabular offset was reduced, and femoral offset increased to maintain global offset. 3D measurements were reproducible with near-perfect observer agreements. 3D data sets should be used for pre- and postoperative measurements in hip arthroplasty.

Comparative study of stem anteversion using a cementless tapered wedge stem in dysplastic hips between the posterolateral and anterolateral approaches.

BACKGROUND: In total hip arthroplasty (THA), the concept of combined anteversion is accepted as one of best indicators of prosthetic joint stability. Technical parameters may influence the stem and cup anteversion. We therefore investigated if stem anteversion could be influenced by surgical approaches in cementless THA using a tapered wedge stem with stem-first technique. HYPOTHESIS: We postulated that the type of approach, posterolateral (PLA) or anterolateral approach (ALA), would influence stem anteversion in dysplastic hip patients. We asked (1) whether stem anteversion was higher in the PLA group and (2) how postoperative stem anteversion was correlated to preoperative femoral anteversion in each group. PATIENTS AND METHODS: We retrospectively compared two groups of hips that underwent THA using a tapered wedge stem with the posterolateral (PLA group; 154 hips) or anterolateral (ALA group; 81 hips) approaches. Computed tomography was utilized to measure femoral neck and stem anteversion. To investigate related factors that affect stem anteversion, a stepwise regression analysis was performed. RESULTS: The stem anteversion in the PLA and ALA groups was 43.7°±9.8° and 34.0°±12.3°, respectively (p<0.01). The stepwise selection process resulted in a model involving femoral neck anteversion and surgical approach (p<0.01). The stem anteversion of the ALA group (r=0.75, p<0.01) was better correlated to femoral neck anteversion than that of the PLA group (r=0.52, p<0.01). DISCUSSION: The stem implantation through the ALA is thought to be more restricted than that through the PLA due to the difference of difficulty in femoral exposure. Tapered wedge stems, which are relatively thin and flat, have a high degree of freedom in the femoral canal. Consequently, in cementless THA using a tapered wedge stem, the surgical approaches affected stem anteversion differently. Stem anteversion was more anatomically restored to femoral neck anteversion through the ALA than through the PLA. LEVEL OF EVIDENCE: III, retrospective case-control study.

Analysis of factors associated with the influence of femoral stem anteversion after total hip arthroplasty / 中国修复重建外科杂志

OBJECTIVE@#To explore the related factors of femoral stem anteversion (FSA) after total hip arthroplasty (THA), so as to provide reference for clinical design of FSA before operation and reduce the risk of hip dislocation after arthroplasty.@*METHODS@#Ninty-three patients (103 hips) who underwent THA between October 2021 and September 2022 and met the selection criteria were selected as the study subjects. Among them, there were 48 males and 45 females with an average age of 58.5 years (range, 25-88 years). Body mass index was 18.00-37.84 kg/m 2, with an average of 24.92 kg/m 2. There were 51 cases (57 hips) of osteonecrosis of femoral head, 35 cases (39 hips) of hip osteoarthritis, and 7 cases (7 hips) of congenital hip dysplasia. Based on CT images, the following indicators were measured: preoperative femoral neck anteversion (FNA), preoperative femoral rotation angle (FRA), preoperative acetabular anteversion (AA), and preoperative combined anteversion (CA; the sum of preoperative FNA and AA); postoperative FSA and the change in femoral anteversion angle (the difference between postoperative FSA and preoperative FNA). Based on preoperative X-ray films, the following indicators were measured: femoral cortical thickness index (CTI) and canal flare index (CFI), the proximal femoral medullary cavity was classified according to Noble classification (champagne cup type, normal type, chimney type), neck-shaft angle (NSA), and femoral offset (FO). Pearson correlation analysis, one-way ANOVA, and Point-biserial correlation analysis were used to investigate the correlation between postoperative FSA, postoperative change in femoral anteversion angle, and patient diagnosis, proximal femoral medullary cavity anatomy type, gender, age, as well as preoperative FNA, FRA, AA, CA, NSA, FO, CTI, and CFI. FSA was used as the dependent variable and the independent variables that may be related to it were included for multiple linear regression analysis.@*RESULTS@#Based on CT image measurement, preoperative FNA was (15.96±10.01)°, FRA (3.36±10.87)°, AA (12.94±8.83)°, CA (28.9±12.6)°, postoperative FSA (16.18±11.01)°, and postoperative change in femoral anteversion angle was (0.22±9.98)°. Based on preoperative X-ray films measurements, the CTI was 0.586±0.081; the CFI was 4.135±1.125, with 23 hips classified as champagne cup type, 68 hips as normal type, and 12 hips as chimney type in the proximal femoral medullary cavity anatomy; NSA was (132.87±7.83)°; FO was (40.53±10.11) mm. There was no significant difference between preoperative FNA and postoperative FSA ( t=-0.227, P=0.821). Pearson correlation analysis showed that postoperative FSA was positively correlated with preoperative FNA, preoperative CA, postoperative change in femoral anteversion angle, and age ( P<0.05), while negatively correlated with preoperative FRA ( P<0.05). The postoperative change in femoral anteversion angle were positively correlated with preoperative FRA and postoperative FSA ( P<0.05), and negatively correlated with preoperative CA and FNA ( P<0.05). One-way ANOVA analysis showed that the above two indicators were not correlated with diagnosis and the proximal femoral medullary cavity anatomy type ( P>0.05). Multiple linear regression analysis showed a linear correlation between FSA and FNA, CA, age, and FRA ( F=10.998, P<0.001), and the best fit model was FSA=0.48×FNA-2.551.@*CONCLUSION@#The factors related to FSA after THA include patient's age, preoperative FNA, CA, FRA and postoperative femoral anteversion, of which preoperative FNA is the most closely related. When designing a surgical plan before surgery, attention should be paid to the patient's preoperative FNA, and if necessary, CT around the hip joint should be scanned to gain a detailed understanding of the proximal femoral anatomical structure.

Defining the medial-lateral axis of the femur: Medical imaging, conventional and functional calibration methods lead to differences in hip rotation kinematics for children with torsional deformities.

Hip rotation during gait is a major indicator for femoral derotation osteotomy. However, repeatability of hip rotation is poor because of discrepancies in determining the medial-lateral axis of the femur. Combining 3D gait analysis with medical imaging allows in vivo evaluation of current clinical methods. We used the condylar axis, identified from low dose biplanar radiographs (EOS imaging Inc), as our reference to evaluate conventional, functional calibration and freehand 3D ultrasound methods to define the medial-lateral axis in children with lower-limb torsional deformities. Twenty participants underwent 3D gait analysis accompanied by freehand 3D ultrasound and biplanar radiographs. The condylar axis identified from biplanar radiographs provided the reference method used to construct the femoral coordinate system. This was used to evaluate a conventional, two functional calibration methods (axis transformation technique and 2DoFKnee) and freehand 3D ultrasound. We measured reliability of 3D localisation of skin markers and anatomical landmarks from the biplanar radiographs. Localisation of skin markers (SD 0.4 mm) and anatomical landmarks (SD 1.3 mm) from the biplanar radiographs were reliable, leading to a precision of 1° for the condylar axis after registration in the motion capture system. The freehand 3D ultrasound produced similar results to the biplanar radiographs reference, with internal hip rotation during gait of 18° and 19° respectively. The conventional and functional calibration methods were predominantly external compared to the reference, with average hip rotation of 4-6° internal. Freehand 3D ultrasound and biplanar radiographs provide reliable means to define the medial-lateral axis of femur for gait analysis, and aid clinical interpretation in children with torsional deformities.

Hip- and patellofemoral-joint loading during gait are increased in children with idiopathic torsional deformities.

BACKGROUND: Torsional deformities of the femur and tibia are associated with gait impairments and joint pain. Several studies have investigated these gait deviations in children with cerebral palsy. However, relatively little is known about gait deviations in children with idiopathic torsion and debate ensues about the management of these patients. RESEARCH QUESTION: What are the effects of idiopathic increased femoral neck anteversion and external tibial torsion on lower-limb kinematics, kinetics and joint loading during gait in children and adolescents. METHODS: Patient-specific musculoskeletal models were created for 12 children/adolescents (mean age of 14 years) with torsional deformities using low-dose biplane radiographic imaging and 3D gait analysis. Comparisons of joint motion and net joint torques during gait were made to an age-matched control group with no torsional deformities. The effects of torsional deformities on muscle and joint contact forces were investigated using two personalised musculoskeletal models: one with normal torsion and another with patient-specific torsion. RESULTS: Femoral neck anteversion and external tibial torsion for the patients were (mean ±â€¯SD) 38°â€¯±â€¯9° and 40°â€¯±â€¯10°, respectively. Patients had increased internal hip rotation and external knee rotation as well as increased pelvic tilt during gait. Additionally, the efficacy of the plantarflexor-knee extension mechanism was diminished. Hip joint contact force was higher in the model with patient-specific torsion. The mediolateral component of the patellofemoral joint contact force was also increased despite the magnitude of the resultant patellofemoral contact force being unchanged. SIGNIFICANCE: It has been previously established that idiopathic lower-limb torsional deformities alter gait kinematics. However, this study also showed that loading of the hip and patellofemoral joints are increased. This is an important insight for the clinical management of these patients and highlights that idiopathic lower-limb torsional deformities are not a purely cosmetic issue.

The anteroposterior axis of the tibia is adjusted to approximately a right angle to the anterior pelvic plane in the standing position in patients with hip dysplasia similar to normal subjects: a cross-sectional study.

BACKGROUND: We previously described that the anteroposterior (AP) axis of the tibia is approximately perpendicular to the transverse axis of the anterior pelvic plane (APP) in the standing position in healthy subjects. The purpose of this study was to investigate the rotational alignment between the APP and clinical epicondylar axis and the AP axis of the tibia relative to pelvic coordination in the standing position in normal subjects and in women with developmental dysplasia of the hip (DDH) to aid decision making for surgeons in the alignment of implants in total hip or knee arthroplasty. METHODS: This study included 77 Japanese women. Twenty-nine in the DDH group underwent curved periacetabular osteotomy; 48 women without lumbago and knee pain were included in the normal group. Femoral neck anteversion (FNA), condylar twist angle, and knee rotation angle were measured in femoral coordination. The angle between the femoral neck axis and clinical epicondylar axis (CEA) was measured, the transverse axis of the APP was also measured, and the angle between the AP axis of the tibia and transverse axis of the APP was calculated. RESULTS: There was a moderate negative correlation between FNA and CEA relative to the APP. This finding indicated a trend towards greater FNA leading to more internal rotation. Knee rotation angle (KRA) relative to the APP was 1.65° ± 5.58° in the normal group and - 2.65° ± 7.57° in the DDH group. This finding indicated that the tibia AP axis was approximately perpendicular to the APP in the standing position both in the normal and DDH groups. CONCLUSION: We found that the tibia AP axis was at approximately a right angle to the transverse axis of the APP in the standing position in both the normal and DDH groups, while the KRA was different in the normal and DDH groups. These findings may prove helpful for positional alignment investigations needed for implantation in total hip or knee arthroplasty and gait analysis.

The anteroposterior axis of the tibia is approximately perpendicular to the anterior pelvic plane in the standing position in healthy Japanese subjects.

BACKGROUND: We previously reported that the clinical epicondylar axis (CEA) was approximately parallel to the transverse axis of the anterior pelvic plane (APP) in the standing position in normal subjects. The purpose of this study was to investigate the rotational alignment between APP in the standing position and the anteroposterior (AP) axis of the tibia relative to pelvic coordination in normal subjects. METHODS: This study included 68 healthy Japanese, 24 males and 44 females, without lumbago and knee pain. Femoral neck anteversion (FNA), condylar twist angle, and knee rotation angle were measured in femoral coordination. The angle between the femoral neck axis and CEA transverse axis of APP was also measured, and the angle between the AP axis of the tibia and the transverse axis of APP was calculated. The mean value of knee rotation angle was 0.23° and 2.06° in male and female subjects, respectively. RESULTS: There was a moderate positive correlation between FNA and the femoral axis angle relative to the transverse axis of APP. The knee rotation angle relative to APP was 0.33° and 1.56° in male and female subjects, respectively, and the tibia AP axis was approximately perpendicular to the transverse axis of APP in the standing position. Regarding validation, we obtained high interclass correlation coefficients for both intraobserver and interobserver reliability. CONCLUSION: We found that the knee rotation angle was almost 0° and that the tibia AP axis was approximately perpendicular to the CEA. The tibia AP axis was also approximately perpendicular to the transverse axis of the APP in standing position.

Measurement of femoral neck anteversion of developmental dislocation of hip in children by 3D printing technique / 中国骨伤

OBJECTIVE@#To explore the method and accuracy of measuring the femoral neck anteversion in children with developmental dislocation of the hip by using 3D printing technology, so as to find out the method of measuring the femoral neck anteversion accurately and guide the formulation of the operation plan.@*METHODS@#From June 2016 to September 2018, 17 patients with unilateral developmental dislocation of the hip were enrolled in the study, including 2 males and 15 females, aged 2 to 13 (5.47±0.81) years old, 11 on the left and 6 on the right. The methods of CT, 3D printing and intraoperative anteversion of femoral neck were used to measure the anteversion of femoral neck respectively. The intraoperative measurement was used as the standard reference value forstatistical analysis, and the accuracy of the first two methods was compared.@*RESULTS@#The average value of CT was (36.00±1.66)°, the average value of model method was(43.91±1.62)°, and the average value of intraoperative method was(44.21±1.62)°. There were significant differences in CT measurement, model measurement and intraoperative measurement(0.05).@*CONCLUSION@#Compared with the traditional CT method, the 3D printing model method is simpler, more accurate and more repeatable, and can simulate the operation before operation. It is an ideal method to measure the femoral neck anteversion.