Aims. The aim of this study was to determine the association between knee alignment and the vertical orientation of the femoral neck in relation to the floor. This could be clinically important because changes of femoral neck orientation might alter chondral joint contact zones and joint reaction forces, potentially inducing problems like pain in pre-existing chondral degeneration. Further, the femoral neck orientation influences the ischiofemoral space and a small ischiofemoral distance can lead to impingement. We hypothesized that a valgus knee alignment is associated with a more vertical orientation of the femoral neck in standing position, compared to a varus knee. We further hypothesized that realignment surgery around the knee alters the vertical orientation of the femoral neck. Methods. Long-leg standing radiographs of patients undergoing realignment surgery around the knee were used. The hip-knee-ankle angle (HKA) and the vertical orientation of the femoral neck in relation to the floor were measured, prior to surgery and after osteotomy-site-union. Linear regression was performed to determine the influence of knee alignment on the vertical orientation of the femoral neck. Results. The cohort included 147 patients who underwent knee realignment-surgery. The mean age was 51.5 years (SD 11). Overall, 106 patients underwent a valgisation-osteotomy, while 41 underwent varisation osteotomy. There was a significant association between the orientation of the knee and the coronal neck-orientation. In the varus group, the median orientation of the femoral neck was 46.5° (interquartile range (IQR) 49.7° to 50.0°), while in the valgus group, the orientation was 52.0° (IQR 46.5° to 56.7°; p < 0.001). Linear regression analysis revealed that HKA demonstrated a direct influence on the coronal neck-orientation (β = 0.5 (95% confidence interval (CI) 0.2 to 0.7); p = 0.002). Linear regression also showed that realignment surgery was associated with a significant influence on the change in the coronal femoral neck orientation (β = 5.6 (95% CI 1.5 to 9.8); p = 0.008). Conclusion. Varus or valgus knee alignment is associated with either a more horizontal or a more vertical femoral neck orientation in standing position, respectively. Subsequently, osteotomies around the knee alter the vertical orientation of the femoral neck. These aspects are of importance when planning osteotomies around the knee in order to appreciate the effects on the adjacent hip joint. The concept may be of even more relevance in dysplastic hips. Cite this article: Bone Jt Open 2021;2(12):1057–1061

Introduction. Most of studies on Total Hip Arthroplasty (THA) are focused on acetabular cup orientation. Even though the literature suggests that femoral anteversion and combined anteversion have a clinical impact on THA stability, there are not many reports on these parameters. Combined anteversion can be considered morphologically as the addition of anatomical acetabular and femoral anteversions (Anatomical Combined Anatomical Anteversion ACA). It is also possible to evaluate the Combined Functional Anteversion (CFA) generated by the relative functional position of femoral and acetabular implants while standing. This preliminary study is focused on the comparison of the anatomical and functional data in asymptomatic THA patients. Material and methods. 50 asymptomatic unilateral THA patients (21 short stems and 29 standard stems) have been enrolled. All patients underwent an EOS low dose evaluation in standing position. SterEOS software was used for the 3D measurements of cup and femur orientation. Cup anatomical anteversion (CAA) was computed as the cup anteversion in axial plane perpendicular to the Anterior Pelvic Plane. Femoral anatomical anteversion (FAA) was computed as the angle between the femoral neck axis and the posterior femoral condyles in a plane perpendicular to femoral mechanical axis. Functional anteversions for the cup (CFA) and femur (FFA) were measured in the horizontal axial patient plane in standing position. Both anatomical and functional cumulative anteversions were calculated as a sum. All 3D measures were evaluated and compared for the repeatability and reproducibility. Statistical analysis used Mann-Whitney U-test considering the non-normal distribution of data and the short number of patients (<30 for each group). Results. Functional cumulative anteversion was significantly higher than anatomical cumulative anteversion for all groups (p<0.05). No significant difference could be noted between the cases according to the use of short or standard stems. Conclusion. This study shows the difference of functional implant orientation as compared to the anatomical measurements. This preliminary study has limitations. First the limited sample of patients. Then this series only includes asymptomatic subjects. Nevertheless, this work focused on the feasibility of the measurements shows the potential interest of a functional analysis of cumulated anteversion. Standing position influences the relative position of THA implants according to the frontal and sagittal orientation of the pelvis. The relevance of these functional measurements in instability cases must be demonstrated, especially in patients with anterior subluxation in standing position which is potentially associated with pelvic adaptative extension. Further studies are needed for the feasibility of measurements on EOS images in sitting position and their analysis in case of instability. For any figures or tables, please contact authors directly

The sagittal orientation of the pelvis commonly called pelvic tilt has an effect on the orientation of the cup in total hip arthroplasty (THA). Pelvic tilt is different between individuals and changes during activities of daily living. In particular the pelvic tilt in standing position should be considered during the planning of THA to adapt the target angles of the cup patient-specifically to minimise wear and the risk of dislocation. Methods to measure pelvic tilt require an additional step in the planning process, may be time consuming and require additional devices or x-ray imaging. In this study the relationship between three functional parameters describing the sagittal pelvic orientation in standing position and seven morphological parameters of the pelvis was investigated. Correlations might be used to estimate the pelvic tilt in standing position by the morphology of the pelvis in order to avoid additional measuring techniques of pelvic tilt in the planning process of THA. For 18 subjects a semi-automatic process was established to match a 3D-reconstruction of the pelvis from CT scans to orthogonal EOS imaging in standing position and to calculate the morphological and functional parameters of the pelvis subsequently. The two strongest correlations of the linear correlation analysis were observed between morphological pelvic incidence and functional sacral slope (r = 0.78; p = 0.0001) and between morphological pubic symphysis-posterior superior iliac spines-ratio and functional tilt of anterior pelvic plane (r = −0.59; p = 0.0098). The results of this study suggest that patient-specific adjustments to the orientation of the cup in planning of THA without additional measurement of the sagittal pelvic orientation in standing position should be based on the correlation between morphological pelvic incidence and functional sacral slope

Background. Cup anteversion and inclination are important to avoid implant impingement and dislocation in total hip arthroplasty (THA). However, it is well known that functional cup anteversion and cup inclination also change as the pelvic sagittal inclination (PSI) changes, and many reports have been made to investigate the PSI in supine and standing positions. However, the maximum numbers of subjects studied are around 150 due to the requirement of considerable manual input in measuring the PSIs. Therefore, PSI in supine and standing positions were measured fully automatically with a computational method in a large cohort, and the factors which relate to the PSI change from supine to standing were analyzed in this study. Methods. A total of 422 patients who underwent THA from 2011 to 2015 were the subjects of this study. There were 83 patients with primary OA, 274 patients with DDH derived secondary OA (DDH-OA), 48 patients with osteonecrosis, and 17 patients with rapidly destructive coxopathy (RDC). The median age of the patient was 61 (range; 15–87). Preoperative PSI in supine and standing positions were measured and the number of cases in which PSI changed more than 10° posteriorly were calculated. PSI in supine was measured as the angle between the anterior pelvic plane (APP) and the horizontal line of the body on the sagittal plane of APP, and PSI in standing was measured as the angle between the APP and the line perpendicular to the horizontal surface on the sagittal plane of APP (Fig. 1). The value was set positive if the pelvis was tilted anteriorly and was set negative if the pelvis tilted posteriorly. Type of hip disease, sex, and age were analyzed with multiple logistic regression analysis if they were related to PSI change of more than 10°. For accuracy verification, PSI in supine and standing were measured manually with the previous manual method in 100 cases and were compared with the automated system used in this study. Results. The median PSI in the supine position was 5.1° (interquartile range [IQR]: 0.4 to 9.4°), and the median PSI in the standing position was −1.3° (IQR: −6.5 to 4.2°). There were 79 cases (19%) in which the PSI changed more than 10° posteriorly from supine to standing with a maximum change of 36.9° (Fig. 2). In the analysis of the factors, type of hip disease (p = 0.015) and age (p = 0.006, Odds Ratio [OR] = 1.035) were the significant factors. The OR of primary OA (p = 0.005, OR: 2.365) and RDC (p = 0.03, OR: 3.146) were significantly higher than DDH-OA. In accuracy verification, the automated PSI measurement showed ICC of 0.992 (95% CI: 0.988 to 0.955) for supine measurement and 0.978 (95% CI: 0.952 to 0.988) for standing measurement. Conclusions. PSI changed more than 10° posteriorly from supine to standing in 19% of the cases. Age and diagnosis of primary OA and RDC were related to having their pelvis recline more than 10° posteriorly. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Introduction. Optimal implant position is critical to hip stability after total hip arthroplasty (THA). Recent literature points out the importance of the evaluation of pelvic position to optimize cup implantation. The concept of Functional Combined Anteversion (FCA), the sum of acetabular/cup anteversion and femoral/stem neck anteversion in the horizontal plane, can be used to plan and control the setting of a THA in standing position. The main purpose of this preliminary study is to evaluate the difference between the combined anteversion before and after THA in weight-bearing standing position using EOS 3D reconstructions. A simultaneous analysis of the preoperative lumbo pelvic parameters has been performed to investigate their potential influence on the post-operative reciprocal femoro-acetabular adaptation. Material and Methods. 66 patients were enrolled (unilateral primary THAs). The same mini-invasive anterolateral approach was performed in a lateral decubitus for all cases. None of the patients had any postoperative complications. For each case, EOS full-body radiographs were performed in a standing position before and after unilateral THA. A software prototype was used to assess pelvic parameters (sacral slope, pelvic version, pelvic incidence), acetabular / cup anteversion, femoral /stem neck anteversion and combined anteversion in the patient horizontal functional plane (the frontal reference was defined as the vertical plane passing through centers of the acetabula or cups). Sub-analysis was made, grouping the sample by pelvic incidence (<55°, 55°–65°, >65°) and by pre-operative sacral slope in standing position (<35°, 35°–45°, >45°). Paired t-test was used to compare differences between preoperative and postoperative parameters within each subgroup. Statistical significance was set at p < 0.05. Results. In the full sample, mean FCA increased postoperatively by 9,3° (39,5° vs 30,2°; p<0.05). In groups with sacral slope < 35° and sacral slope > 45°, postoperative combined anteversion increased significantly by 11,7° and 12,9°, respectively. In the group with pelvic incidence > 65°, postoperative combined anteversion increased significantly by 14,4°. There was no significant change of combined anteversion in the remaining subgroups. Discussion. In this series the FCA increased after THA, particularly in patients with a low or high sacral slope on the pre-operative evaluation in standing position. This may be related to a greater difficulty for the surgeon in anticipating the postoperative standing orientation of the pelvis in these patients, as they were standardly oriented during surgery (lateral decubitus). Interestingly the combined anteversion was also increased in patients with a high pelvic incidence that is commonly associated with a high sacral slope. Conclusion. Post-operative increase of anatomical cumulative anteversion has been previously reported using anterior approach. The FCA concept based on EOS 3D reconstructions brings new informations about the reciprocal femoro-acetabular adaptation in standing position. Differences found in combined anteversion before and after the surgery show that a special interest should be given to patients with high pelvic incidence and low or high sacral slope, to optimize THA orientation in standing position

Aims: For planning of Total Hip Arthroplasties (THA) plain X-rays of the pelvis in anterior posterior orientation are used. New methods such as CT scans and intraoperative digitization with navigation devices introduce the third dimension into orthopaedic planning. In order to compare measurements derived from three-dimensional data-acquisition with standard pelvic measurements it is important to estimate the underlying variances of those standards. Methods: 120 patients were investigated and subdivided in 4 groups depending of their age or the condition of their hip joints. The patients were positioned in a supine position on a table and in a standing position. Three landmarks at the patientñs pelvis (left and right anterior superior iliac spine (ASIS) and the pubic tubercle (PT)) were percutaneously digitized with a digitizing arm (Micro-Scribe-3DX, Vizion, Glendale, CA). The pelvic positions in space were calculated in relation to the horizontal and the vertical plane. Results: Despite the anatomical deþnition (0¡), we found an inclination of 4-6¡. There is no signiþcant difference between supine and standing position and no signiþcant difference between the groups and no diffenrence between genders. All patients lyed ßat in supine position without special positioning effort Conclusions: The pelvis orientation ist very stable in standing as well in supine position no matter if the patient is old or young, has coxarthrosis ore none or a THA. Therefore it can be concluded that our knowledge derived from measurements of planar a.-p.x-rays is not inßuenced by a massive variance in pelvic positions

Introduction. Optimal implant position is the important factor in the hip stability after THA. Both the acetabular and femoral implants are placed in anteversion. While most hip dislocations occur either in standing position or when the hip is flexed, preoperative hip anatomy and postoperative implants position are commonly measured in supine position with CT scan. The isolated and combined anteversions of femoral and acetabular components have been reported in the literature. The conclusions are questionable as the reference planes are not consistent: femoral anteversion is measured according to the distal femoral condyles plane (DFCP) and acetabulum orientation in the anterior pelvic plane (APP)). The EOS imaging system allows combined measurements for standing position in the “anatomical” reference plane or anterior pelvic plane (APP) or in the patient “functional” plane (PFP) defined as the horizontal plane passing through both femoral heads. The femoral anteversion can also be measured conventionally according to the DFCP. The objective of the study was to determine the preoperative and postoperative acetabular, femoral and combined hip anteversions, sacral slope, pelvic incidence and pelvic tilt in patients who undergo primary THA. Material and Methods. The preoperative and postoperative 3D EOS images were assessed in 62 patients (66 hips). None of these patients had spine or lower extremity surgery other than THA surgery in between the 2 EOS assessments. None had dislocation within the follow up time period. Results. Pelvic values. The preoperative sacral slope was 42.4°(11° to 76°) as compared to the postoperative sacral slope (40.3°, −4° to 64°)(p=0.014). The preoperative pelvic tilt was 15.3° (−10° to 44°) as compared to the postoperative tilt (17.2°, −6° to 47°)(p=0.008). The preoperative pelvic incidence was 57.7°(34° to 93°) and globally unchanged as compared to the postoperative incidence (57.5°, 33° to 79°)(p=0.8). Acetabular values. Surgeons increased the anteversion according to the APP by an average of 12.6°(−13° to 53°)(p<0.001). Acetabular anteversion was increased by 14.3° in the PFP (−11° to 51°)(p<0.001). Femoral values. In the DFCP, preoperative neck anteversion was decreased postoperatively by an average of −3,2°(−48° to 33°)(p=0,0942). In the PFP, preoperative neck anteversion was decreased postoperatively by an average of −6,3°(−47° to 17°)(p<0,001). Combined values. According to the classical methods (acetabular orientation in the APP and femoral anteversion in the DFCP), mean preoperative combined anteversion was 36.1° (4° to 86°) and was increased postoperatively to 45.5°(−12° to 98°)(p=0.0003). According to the PFP, mean preoperative combined anteversion was 30,7°(5° to 68°) and was increased postoperatively to 38,8°(−10° to 72°)(p=0,0001). Conclusion. This study reports two methods for the measurement of acetabular and femoral anteversion, “anatomical” according to the APP and DFCP and “functional” according to the PFP. Surgeons tend to increase the anteversion of the acetabular implant and to decrease femoral anteversion during the surgery. The trend is the same for postoperative evolution of values using the “anatomical” or the “functional” methods but numerical discrepancies are explained by significant APP orientation changes. The assessment of the true combined anteversion provides new perspectives to optimize our understanding of THA stability and function

Introduction. The assessment of leg length is essential for planning the correction of deformities and for the compensation of length discrepancy, especially after hip or knee arthroplasty. CT scan measures the “anatomical” lengths but does not evaluate the “functional” length experienced by the patients in standing position. Functional length integrates frontal orientation, flexion or hyperextension. EOS system provides simultaneously AP and lateral measures in standing position and thus provides anatomical and functional evaluations of the lower limb lengths. The objective of this study was to measure 2D and 3D anatomical and functional lengths, to verify whether these measures are different and to evaluate the parameters significantly influencing these potential differences. Material and Methods. 70 patients without previous surgery of the lower limbs (140 lower extremities) were evaluated on EOS images obtained in bipodal standing position according to a previously described protocol. We used the following definitions:. anatomical femoral length between the center of the femoral head (A) and center of the trochlea (B). anatomical tibial length between the center tibial spine (intercondylar eminence) (C) and the center of the ankle joint (D). functional length is AD. global anatomical length is AB + CD. Other parameters measured are HKA, HKS, femoral and tibial mechanical angles (FMA, TMA), angles of flexion or hyperextension of the knee, femoral and tibial torsion, femoro-tibial torsion in the knee, and cumulative torsional index (CTI). All 2D et3D measures were evaluated and compared for their repeatability. Results. Regarding repeatability, an ICC> 0.95 was found for all measurements except for the tibial mechanical angle (0.91 for 2D, 3D 0.92 for 3D). We observed 54/140 lower limbs with Flessum/Recurvatum angles (FRA) >10°. 2D results (mean, SD) were. 41,8mm(2,9) for femoral anatomical length. 36,1mm(2,8) for tibial anatomical length. 78,0mm(5,4) for global anatomical length. 78,5 mm(5,5) for functional length. 7,4°(12,0) for Flessum/Recurvatum angle. −1,5°(6,4) for HKA. 4,9°(2,0) for HKS. 92,1°(3,4) for FMA. 87,1°(3,4) for TMA. 3D results (mean, SD) were. 42,4mm (2,8) for femoral anatomical length. 36,6mm (2,8) for tibial anatomical length. 79,0mm (5,4) for global anatomical length. 78,9mm (5,5) for functional length. 7,2°(12,0) for Flessum/Recurvatum angle. −1,0°(5,9) for HKA. 4,9°(1,5) for HKS. 92,7°(2,7) for FMA. 87,9°(3,9) for TMA. The 2D/3D measurements of functional lengths were statistically significant (p <0.0001. Student's test). For anatomical lengths. 2D/3D measurements were also statistically significant (p <0.0001. Student's test for femoral tibial and global anatomical lengths). Some parameters significantly influenced 2D/3D differences:. for the global anatomical length: FRA P<0,0001, TMA P=0,0173, HKA P=0,0259 and femoro-tibial torsion P=0,0026. for the functional length FRA P=0,0065. Discussion and conclusion. EOS imaging allows to accurately assess the anatomical and functional length experienced by the patient. These new data open new perspectives for planning length or axis corrections and for an optimized evaluation in some medico legal issues after joint replacement or posttraumatic sequelae. This study points out the importance of 3D measurements in outliers cases (varus or valgus cases, flessum or recurvatum of the knee)

Introduction. The position and orientation of the lower extremities are fundamental for planning and follow-up imaging after arthroplasty and lower extremity osteotomy. But no studies have reported the reproducibility of measurements over time in the same patient, and experience shows variability of the results depending on the protocols for patient positioning. This study explores the reproducibility of measurements in the lower extremity with the patients in “comfortable standing position” by the EOS® imaging system. Materials and Methods. Two whole-body acquisitions were performed in each of 40 patients who were evaluated for a spine pathology. The average interval between acquisitions was 15 months (4–35 months). Patients did not have severe spine pathology and did not undergo any surgery between acquisitions. The “comfortable standing position” is achieved without imposing on the patient any specific position of the lower limbs and pelvis. All the measurements were performed and compared in both 2- and 3-dimensional images. Distances between the centers of the femoral heads and between the centers of the knees and ankles were measured from the front. The profile is shown by the flexion angle between the axis of the femur (center of the femoral head and the top of the line Blumensaat) and the axis of the tibia. Results. The average radiation dose was 0.80 mGy (0.5–1.11). For the first acquisition, the mean distance between the femoral heads was 17.9 cm (15.8–20.2), the mean distance between the middle of the knee joints was 16.7 cm (11.2–23.1) and the mean distance between the medial malleoli was 13.1 cm (0 to 18). For the second acquisition, the mean distance between the femoral heads was 17.9 cm (14.9–21.5), the mean distance between the middle of the knee joints was 16.9 cm (11.4–23.1) and the mean distance between the medial malleoli was 13.6 cm (0–19.4). For all comparisons no significant difference was demonstrated in related samples by Wilcoxon rank test and paired Student t test. Discussion. Two- and 3-dimensional data are not affected by repeated acquisitions several to many months apart in “comfortable standing position.” This work shows the reproducibility of measurements of the lower extremity in the “comfortable standing position” by the EOS® imaging system. Additional research should be considered for combined measures in the face-profile position of each patient

Acetabular component positioning is commonly referenced with the pelvis in the supine position in direct anterior approach THA. Changes in pelvic tilt (PT) from the pre-operative supine to the post-operative standing positions have not been well investigated and may have relevance to optimal acetabular component targeting for reduced risk of impingement and instability. The aims of this study were therefore to determine the change in PT that occurs from pre-operative supine to post-operative standing, and whether any factors are associated with significant changes in tilt ≥13° in posterior direction. 13° in a posterior direction was chosen as that amount of posterior rotation creates an increase in functional anteversion of the acetabular component of 10°. 1097 THA patients with pre-operative supine CT and standing lateral radiographic imaging and 1 year post-operative standing lateral radiographs (interquartile range 12–13 months) were reviewed. Pre-operative supine PT was measured from CT as the angle between the anterior pelvic plane (APP) and the horizontal plane of the CT device. Standing PT was measured on standing lateral x-rays as the angle between the APP and the vertical line. Patients with ≥13° change from supine pre-op to standing post-op (corresponding to a 10° change in cup anteversion) were grouped and compared to those with a <13° change using unpaired student's t-tests. Mean pre-operative supine PT (3.8±6.0°) was significantly different from mean post-operative standing PT (−3.5±7.1°, p<0.001), ie mean change of −7.3±4.6°. 10.4% (114/1097) of patients had posterior PT changes ≥13° supine pre-op to standing post-op. A significant number of patients, ie 1 in 10, undergo a clinically significant change in PT and functional anteversion from supine pre-op to standing post-op. Surgeons should be aware of these changes when planning component placement in THA

Purpose and Background. Work-related musculoskeletal disorders (WRMSD) can affect 56–80% of physiotherapists. Patient handling is reported as a significant risk factor for developing WRMSD with the back most frequently injured. Physiotherapists perform therapeutic handling to manually assist and facilitate patients’ movement to aid rehabilitation, which can increase physiotherapists risk of experiencing high forces during patient handling. Methods and Results. A descriptive cross-sectional study was completed to explore and quantitatively measure the movement of ten physiotherapists during patient handling, over one working day, in a neurological setting. A wearable 3-dimensional motion analysis system, Xsens (Movella, Henderson, NV), was used to measure physiotherapist movement and postures in the ward setting during patient treatment sessions. The resulting joint angles were reported descriptively and compared against a frequently used ergonomic assessment tool, the Rapid Upper Limb Assessment (RULA). Physiotherapists adopted four main positions during patient handling tasks: 1) kneeling; 2) half-kneeling; 3) standing; and 4) sitting. Eight patient handling tasks were identified and described: 1) Lie-to-sit; 2) sit-to-lie; 3) sit-to-stand; facilitation of 4) upper limb; 5) lower limb; 6) trunk; and 7) standing treatments; and 8) walking facilitation. Kneeling and sitting positions demonstrated greater neck extension and greater lumbosacral flexion during treatments which scores highly with the RULA. Conclusion. This research identified that patient treatment tasks were more often performed in kneeling or sitting positions than standing. Current moving and handling guidance teaches moving and handling in a standing position; loading and stresses experienced by the physiotherapists may differ in sitting or kneeling positions. Conflicts of interest. None. Sources of funding. None. This work has been presented as a poster at the CSP conference Glasgow 2023

Introduction. Assessment of the humeral head translation with respect to the glenoid joint, termed humeral head migration (HHM), is crucial in total shoulder arthroplasty pre-operative planning. Its assessment informs current classification systems for shoulder osteoarthritis as well as the evaluation of surgical correction. In current clinical practice, HHM assessment relies on computed-tomography (CT) imaging. However, the associated supine position might undermine its functional relevance as it does not reflect the weight-bearing condition with active muscle engagement associated with the upright standing position of most daily activities. Therefore, we assessed to what extent HHM in a supine position is associated with HHM in a range of functional arm positions. Method. 26 shoulder osteoarthritis patients and 12 healthy volunteers were recruited. 3D shapes of the humerus and scapula were reconstructed from their respective CT scans using an image processing software. 3. , and their CT-scan-based HHMs were measured. Furthermore, all subjects underwent low-dose biplanar radiography . 4. in four quasi-static functional arm positions while standing: relaxed standing, followed by 45 degrees of shoulder extension, flexion, and abduction. Using a previously validated method implemented in the programming platforms. 5. , 3D shapes were registered to the pairs of biplanar images for each arm position and the corresponding functional HHM was measured. Bivariate correlations were assessed between the CT-based HHM and each functional arm position. Result. HHM in 45 degrees of flexion and extension both showed significant and strong correlations (r>0.66 and P<0.01) with HHM assessed in the supine position. However, such a high correlation was not found for relaxed standing and 45 abduction. Conclusion. Although HHM in a supine position correlates with HHM in 45-degree extension and flexion, it is poorly associated with the HHM in abduction and relaxed standing. These results may suggest the inclusion of more functionally-relevant patient positioning toward better-informed shoulder arthroplasty planning. Acknowledgement. Funding from PRosPERos-II Project

Biomedical imaging is essential in the diagnosis of musculoskeletal pathologies and postoperative evaluations. In this context, Cone-Beam technology-based Computed Tomography (CBCT) can make important contributions in orthopaedics. CBCT relies on divergent cone X-rays on the whole field of view and a rotating source-detector element to generate three-dimensional (3D) volumes. For the lower limb, they can allow acquisitions under real loading conditions, taking the name Weight-Bearing CBCT (WB-CBCT). Assessments at the foot, ankle, knee, and at the upper limb, can benefit from it in situations where loading is critical to understanding the interactions between anatomical structures. The present study reports 4 recent applications using WB-CBCT in an orthopaedic centre. Patient scans by WB-CBCT were collected for examinations of the lower limb in monopodal standing position. An initial volumetric reconstruction is obtained, and the DICOM file is segmented to obtain 3D bone models. A reference frame is then established on each bone model by virtual landmark palpation or principal component analysis. Based on the variance of the model point cloud, this analysis automatically calculates longitudinal, vertical and mid-lateral axes. Using the defined references, absolute or relative orientations of the bones can be calculated in 3D. In 19 diabetic patients, 3D reconstructed bone models of the foot under load were combined with plantar pressure measurement. Significant correlations were found between bone orientations, heights above the ground, and pressure values, revealing anatomic areas potentially prone to ulceration. In 4 patients enrolled for total ankle arthroplasty, preoperative 3D reconstructions were used for prosthetic design customization, allowing prosthesis-bone mismatch to be minimized. 20 knees with femoral ligament reconstruction were acquired with WB-CBCT and standard CT (in unloading). Bone reconstructions were used to assess congruency angle and patellar tilt and TT-TG. The values obtained show differences between loading and unloading, questioning what has been observed so far. Twenty flat feet were scanned before and after Grice surgery. WB-CBCT allowed characterization of the deformity and bone realignment after surgery, demonstrating the complexity and multi-planarity of the pathology. These applications show how a more complete and realistic 3D geometric characterization of the of lower limb bones is now possible in loading using WB-CBCT. This allows for more accurate diagnoses, surgical planning, and postoperative evaluations, even by automatisms. Other applications are in progress

Introduction. The posterior condylar axis of the distal femur is the common reference used to describe femoral anteversion. In the context of Total Hip Arthroplasty (THA), this reference can be used to define the native femoral anteversion, as well as the anteversion of the stem. However, these measurements are fixed to a femoral reference. The authors propose that the functional position of the proximal femur must be considered, as well as the functional relationship between stem and cup (combined anteversion) when considering the clinical implications of stem anteversion. This study investigates the post-operative differences between anatomically-referenced and functionally-referenced stem and combined anteversion in the supine and standing positions. Method. 18 patients undergoing pre-operative analysis with the Trinity OPS® planning (Optimized Ortho, Sydney Australia, a division of Corin, UK) were recruited for post-operative assessment. Anatomic and functional stem anteversion in both the supine and standing positions were determined. The anatomic anteversion was measured from CT and referenced to the posterior condyles. The supine functional anteversion was measured from CT and referenced to the coronal plane. The standing functional anteversion was measured to the coronal plane when standing by performing a 3D/2D registration of the implants to a weight-bearing AP X-ray. Further, functional acetabular anteversion was captured to determine combined functional anteversion in the supine and standing positions. Results. The average anatomical stem anteversion was 9.9° (6.7° to 13.0°). In all cases, the anatomical stem anteversion was different than the measured functional stem anteversion in both the supine and standing positions. The functional femoral anteversion decreased from supine to stand by an average of 7.1° (4.9°−9.2°), suggesting more internal rotation of the femurs when weight-bearing. In all patients, the pelvis rotated posteriorly in the sagittal plane from supine to standing, increasing the functional acetabular anteversion by a mean of 5.1°. Conclusions. Anatomic stem anteversion differs significantly from functional stem anteversion in both the supine and standing positions, as a consequence of the patient specific differences in internal/external rotation of the femur in the functional postures. In the same way that the Anterior Pelvic Plane is now widely recognized as an inappropriate reference for cup orientation due to variation in sagittal pelvic tilt, referencing the femoral stem anteversion to the native anatomy (distal femur) maybe also be misleading and not provide a suitable description of the functional anteversion of the stem. This has implications for determining optimal combined alignment in THA

The anterior pelvic plane (APP) angle is often used as a reference to decide pelvic alignment for hip surgeons. However, Rousseau criticised the validness of the APP angles because the APP angles in standing position measured on conventional standing X-ray films never showed correlation with the other pelvic alignment parameters, such as sacral slope (SS). We measured the APP angles, SS and pelvic tilt (PT) on the non-distorted anteroposterior (AP) and lateral digitally reconstructed radiography (DRR) images in supine position (with CT scans) and AP and lateral X-ray images in standing position (with EOS X-ray machine [EOS imaging, Paris, France]) by using of the same EOS software. Our data showed that the pre- and post-operative APP angles correlated with SS and PT in both supine and standing positions. Our non-distorted high quality images and the EOS software revealed these correlations. Therefore, we can still use the APP angles to decide pelvic alignment for patients who undergo total hip arthroplasty (THA). Recent papers demonstrated positional or chronological dramatic changes of the APP angles between pre- and post-operative states in patients who underwent THA. The EOS system will be a powerful tool to investigate these changes of the pelvic alignments

In total hip arthroplasty (THA), inappropriate cup alignment cause edge loading and prosthetic impingement, which lead to various mechanical problems including dislocation, excessive wear and breakage of bearing materials, and stem neck fracture. To find the optimal cup alignment, various computer simulation studies have been conducted. However there have been few studies focusing on pelvic coordinate system as a reference of cup positioning. Our hypothesis is that the functional pelvic coordinate system with pelvic sagittal inclination in the supine position is appropriate for a reference frame of cup alignment. To test the hypothesis, we have been investigating preoperative and postoperative kinematics of pelvis and hip of THA patients. In 25 % of the consecutive 163 patients, the difference in preoperative pelvic inclination angle between the supine and standing positions (positional change of pelvic inclination [PC]) was 10. o. or more. Patients’ age and age-related spinal disorders including compression fracture and lumbar spondylolisthesis were independent factors associated with large preoperative PC. This raises a concern that large PC might increase the risk of edge loading and posterior prosthetic impingement when cup was positioned referencing supine pelvic position, especially in elderly patients. We compared kinematics of the hip after THA in patients with a preoperative large PC (≥10°) with that in patients with a preoperative small PC (<10°), assuming that the supine position as a zero position of the pelvis. First, we compared intraoperative passive range of motion (ROM) after implantation of the 91 hips using navigation system. No significant differences in intraoperative hip ROM were observed between the both groups. Next, we compared postoperative ROM of the 50 hips during motion of daily livings using our 4-dimentional motion analysis system within two year after THA. No significant differences in postoperative hip flexion or extension angles were observed between the both groups. These results suggested that if cup was positioned referencing the supine pelvic position, the degree of preoperative PC does not matter early after primary THA. Regarding long-term change of pelvic inclination after THA, 49 % of 70 patients followed for 10 years showed the change more than 10. o. in the standing position, although only 9% showed the change more than 10. o. in the supine position. This means that aging after THA increase discrepancy of pelvic inclination between the preoperative supine position as the reference for preoperative planning and the postoperative standing positions in some patients. However we could not find any preoperative predictors of this long-term change of pelvic inclination in the standing position. Therefore, although it is unclear whether surgeons should change the reference pelvic plane for cup alignment taking the longitudinal change of pelvic inclination in the standing position, at least, strict cup alignment control at primary THA is considered to be important to minimize the risk of edge loading and prosthetic impingement due to longitudinal changes of pelvic inclination. In conclusion, our current recommendation of pelvic coordinate system as a reference of cup alignment is a functional pelvic coordinate system with pelvic sagittal inclination in supine position

Aims. Iliopsoas impingement occurs in 4% to 30% of patients after undergoing total hip arthroplasty (THA). Despite a relatively high incidence, there are few attempts at modelling impingement between the iliopsoas and acetabular component, and no attempts at modelling this in a representative cohort of subjects. The purpose of this study was to develop a novel computational model for quantifying the impingement between the iliopsoas and acetabular component and validate its utility in a case-controlled investigation. Methods. This was a retrospective cohort study of patients who underwent THA surgery that included 23 symptomatic patients diagnosed with iliopsoas tendonitis, and 23 patients not diagnosed with iliopsoas tendonitis. All patients received postoperative CT imaging, postoperative standing radiography, and had minimum six months’ follow-up. 3D models of each patient’s prosthetic and bony anatomy were generated, landmarked, and simulated in a novel iliopsoas impingement detection model in supine and standing pelvic positions. Logistic regression models were implemented to determine if the probability of pain could be significantly predicted. Receiver operating characteristic curves were generated to determine the model’s sensitivity, specificity, and area under the curve (AUC). Results. Highly significant differences between the symptomatic and asymptomatic cohorts were observed for iliopsoas impingement. Logistic regression models determined that the impingement values significantly predicted the probability of groin pain. The simulation had a sensitivity of 74%, specificity of 100%, and an AUC of 0.86. Conclusion. We developed a computational model that can quantify iliopsoas impingement and verified its accuracy in a case-controlled investigation. This tool has the potential to be used preoperatively, to guide decisions about optimal cup placement, and postoperatively, to assist in the diagnosis of iliopsoas tendonitis. Cite this article: Bone Jt Open 2023;4(1):3–12

The reduction for unstable femoral intertrochanteric fracture should be extramedullary, which means that the proximal fragment protrudes for the distal fragment. However, only few articles have compared extramedullary and intramedullary reductions in a biomechanical study. Thus, we created unstable femoral intertrochanteric fracture models using imitational bone (extramedullary and intramedullary groups, each with 12 cases) and evaluated their biomechanical stabilities. The fracture type was 31-A2 according to the AO-OTA Classification of Fractures and Dislocations and greatly lacked bone on the posterior side. We performed compression examination and evaluated stiffness. The implant used for fixation was TFNA (DePuy Synthes). We applied axial compression with 20 adduction in the standing position. Statistical analysis was performed using the Mann-Whitney U test. No significant difference in initial loading force was found between the two groups. However, the axial stiffness of the extramedullary bone showed a significant increase (p < 0.05) in high loading force (800–1000 N). This means that the stability of the extramedullary reduction was superior to that of the intramedullary reduction in terms of high loading force in the standing position. We suggest that antero-medial bony buttress is important for unstable femoral intertrochanteric fractures. These data indicate that extramedullary reduction and fixation for unstable femoral intertrochanteric fractures increase stability

Rehabilitation systems based on inertial measurement units (IMU) and bio-feedbacks are increasingly used in many different settings for patients with neurological disorders such as Parkinson disease or balance impairment, and more recently for functional recover after orthopedic surgical interventions or injuries especially concerning the lower limb. These systems claim to provide a more controlled and correct execution of the motion exercises to be performed within the rehabilitation programs, hopefully resulting in a better outcomes with respect to the traditional direct support of a physical therapists. In particular recruitment of specific muscles during the exercise is expression of its correct and finalized execution. The objective of this study was to compare muscular activation patterns of relevant lower limb muscles during different exercises performed with traditional rehabilitation and with a new validated system based on IMU and biofeedback (Riablo, Corehab, Trento, Italy). Twelve healthy subjects (mean age 28.1 ± 3.9, BMI 21.8± 2.1) were evaluated in a rehabilitation center. Muscular activation pattern of gluteus maximum, gluteus medium, rectus femoris and biceps femoris was recorded through surface EMG (Cometa; Milan) during six different motion tasks: hip abduction in standing position, lunge, hip flexion with extended knee in standing position, lateral lunge, hip abduction with extended knee in lateral decubitus, squat. Subjects performed 10 repetitions of each task for a total of 100 repetitions per motion task, with and without Riablo System as well as during standard rehabilitation. An additional IMU was positioned on the shank in order to detect beginning and end of each repetition. A single threshold algorithm was used to identify muscle activation timing. During hip abduction in standing position, gluteus maximum and rectus femoris showed a better and longer activation pattern while using Riablo compared to traditional rehabilitation. Gluteus medium showed a similar activation pattern whereas biceps femoris showed no activation from 30% to 80% using Riablo. During squat, rectus femoris and biceps femoris had a similar activation pattern with and without Riablo whereas gluteus maximum and gluteus medium showed a better activation pattern while using Riablo. The recent development of innovative rehabilitation systems meets the need of manageable, reliable and efficient instruments able to reduce rehabilitation costs but with the same good clinical outcomes. Muscular activation patterns of relevant lower limb muscles during selected motion tasks reveal their correct execution. The use of this new rehabilitation system based on IMU and biofeedback seems to allow a more selective and effective muscular recruitment, likely due to the more correct and controlled execution of the exercise, particularly for the identification and interdiction of possible compensation mechanisms

Materials and Methods. We treated 60 hips in 60 patients (8 males and 52 females) with cementless THA that were performed from January 2007 to December 2009 in our hospital. 48 osteoarthritis hips, 5 rheumatoid arthritis hips and 7 idiopathic osteonecrosis hips were included. All patients were performed THA with VectorVision Hip navigation system (BrainLAB, Feldkirchen, Germany). We used AMS HA cups and PerFix stems (KYOCERA Medical co., Osaka, Japan). The mean age of surgery was 61 years old (35–79 years old). The pelvic inclination angles (PIA) were measured with anteroposterior radiographic image in accordance with the Doiguchi's method. Results. The amount of change of the pelvic inclination angle between supine and standing position was 0.6 degrees prior to surgery, 0.7 degree at 1 year after surgery and 2.4 degrees at 5 years after surgery. 7 patients prior to surgery, 7 patient at 1 year after surgery and 18 patient at 5 year after surgery changed more than 5 degrees between supine and standing position. The pelvic inclination angles of 23 patients prior to surgery, 19 patients at 1 year after surgery and 35 patients at 5 years after surgery changed in the retroverted direction with posture change. It tended to increase after surgery. Discussions and Conclusions. When we place the acetabular component, it is important that the pelvic inclination angle in supine position according to preoperative planning and the change of pelvic inclination angle with posture change. The amount of change of PIA tended to increase at 5 year after surgery compared to 1 year after surgery. Moreover, we experienced some patients the amount of change of pelvic inclination angle between supine and standing position changed more than 10 degrees. If the pelvic inclination angle changes widely, it requires more attention because of a narrow safe margin for placing the acetabular component