Cone beam CT doses in radiotherapy patient positioning in Finland-prostate treatments.

Imaging parameters, frequencies and resulting patient organ doses in treatments of prostate cancer were assessed in Finnish radiotherapy centres. Based on a questionnaire to the clinics, Monte Carlo method was used to estimate organ doses in International Commission on Radiological Protection standard phantom for prostate, bladder, rectum and femoral head. The results show that doses from cone beam computed tomography imaging have reduced compared to earlier studies and are between 3.6 and 34.5 mGy per image for the above-mentioned organs and for normal sized patients. There still is room for further optimization of the patient exposure, as many centres use the default imaging parameters, and the length of the imaged region may not be optimal for the purpose.

Role of femoral head material on readmission and mortality rates following elective primary total hip arthroplasty in Medicare patients.

INTRODUCTION: The role of different femoral head materials for total hip arthroplasty (THA) has been widely studied in the context of wear properties and corrosion. Cobalt chrome (CoCr) femoral heads are commonly used as a standard of comparison to other materials such as ceramic and oxidized zirconium (OxZi). This study aims to evaluate the impact of femoral head material on clinical outcomes in elective primary THA patients. METHODS: Retrospective analysis of THA patients within the Medicare claims database between October 2017 and September 2020 using diagnosis-related group codes was conducted. Information collected included sex, age, Charlson Comorbidity Index, and femoral head type. Patients with CoCr femoral heads were compared against patients with either OxZi or ceramic femoral heads using 1:1 propensity score matching. Z-testing and Chi-square analysis were used to determine between-group significance. RESULTS: In total, 112,960 elective THA patients were included, with 56,480 in OxZi or ceramic and 56,480 in CoCr. Readmission rates were lower in patients that received OxZi or ceramic femoral heads at 30-day (p < 0.0001), 60-day (p < 0.0001), and 90-day postoperatively (p < 0.0001) compared to CoCr. Mortality rates were also lower in patients that received OxZi or ceramic femoral heads at 30-day (p = 0.004), 60-day (p = 0.018), and 90-day postoperatively (p = 0.009) compared to CoCr. CONCLUSION: CoCr femoral heads had higher rates of readmissions and mortality compared to OxZi or ceramic. Further analysis of bearing surface combinations and sub-group analyses to determine significance between-group differences is needed. LEVEL III EVIDENCE: Retrospective analysis.

Radiographic and Dynamic Assessment for Resection of Cam Lesions in Patients With Femoroacetabular Impingement.

Cam-type femoroacetabular impingement is characterized by a pathologic asphericity of the femoral head-neck junction, and arthroscopic femoral osteoplasty is indicated to correct the bony abnormality and restore normal hip mechanics when symptomatic. Residual femoroacetabular impingement deformity after arthroscopy is a leading cause of failure, and it is therefore critical to perform a thorough fluoroscopic and dynamic assessment when addressing cam deformities arthroscopically. The fluoroscopic assessment uses 6 anteroposterior views, including 3 in hip extension (30° internal rotation, neutral rotation, and 30° external rotation) and 3 in 50° flexion (neutral rotation, 40° external rotation, 60° of external rotation), performed before, during, and after the femoral resection. The dynamic assessment includes evaluation of impingement-free range of motion and "end feel" (a subjective description of the tactile feedback during assessment of hip motion), and should be performed before and after the femoral resection in 3 specific positions (extension/abduction, flexion/abduction, and flexion/internal rotation). Although the anterior aspect of the head-neck junction is readily accessed through standard arthroscopic portals with the hip in 30 to 50° of flexion, the posterolateral, posteromedial, and posterior extent of the femoral head-neck junction are challenging to address. The natural external rotation of the proximal femur during flexion and internal rotation during extension can be used to gain posterior lateral and medial access. Antero/posteromedial femoral access can be obtained with >50° of hip flexion with the burr in the anteromedial portal. Posterolateral femoral access is achieved with hip extension with the burr in the anterolateral portal, and further posterolateral access can be achieved with the addition of traction, allowing resection of posterolateral deformities extending beyond the lateral retinacular vessels while remaining proximal to the vessels. This comprehensive intraoperative fluoroscopic and dynamic assessment and surgical technique can lead to a predictable correction of most cam-type deformities.

Intraoperative fluoroscopic safety assessment of femoral head implants with 3-dimensional risk parameters to minimize cut-out.

OBJECTIVE: This study aimed to introduce a method to extract the 3-dimensional spatial position of the femoral head implant from 2-dimensional fluoroscopic projections, allowing surgeons to assess fixation much more accurately and prevent cut-out complications in proximal femoral nailing. METHODS: To define a safety region for the tip in the femoral head, a novel 3-dimensional distance-based risk parameter called TSD3D was introduced. An intersection algorithm was developed that solely takes the fluoroscopic anteroposterior and lateral distances to reveal the 3-dimensional location of the screw or Kirschner wire tip, enabling the utilization of the 3-dimensional parameter. Orthogonal per- spectives of 6 femur proximal bone substitutes with randomly inserted Kirschner wires were imaged under fluoroscopy. The developed algorithm was used to calculate the implant tip location in 3-dimensional from 2-dimensional images for each case. Algorithm accuracy was validated with the computed tomography-obtained 3-dimensional models of the same femur substitutes. RESULTS: The newly introduced risk parameter successfully visualizes 3-dimensional safety regions. Utilizing the 2-dimensional fluoro- scopic distances as inputs to the algorithm, the 3-dimensional position of the implanted Kirschner wire tip is calculated with a maximum of 9.8% error for a single Cartesian-coordinate measurement comparison. CONCLUSION: By incorporating the newly introduced 3-dimensional risk parameter, surgeons can more precisely evaluate the position of the implant and avoid cut-out complications, instead of relying solely on misleading 2-dimensional fluoroscopic projections of the femoral head.

Mechanical parameter assessment of fresh human cancellous bone of the femoral head in atraumatic femoral head necrosis and primary coxarthrosis.

BACKGROUND: Atraumatic femoral head necrosis is a rare pathological change of the femoral head. It is characterized by local necrosis of the cancellous bone as a result of reduced blood supply to the bone. Even today it remains unclear how to assess the hardness of the necrosis, whether it is soft tissue that is easily removed, or hard tissue that is difficult to resect. METHODS: Femoral heads with primary coxarthrosis were selected as a comparison group. For this purpose, 49 femoral heads obtained during total hip arthroplasty surgery with either condition (23 femoral head necrosis, 26 coxarthrosis) were transferred to the testing laboratory in fresh condition. Cylindrical specimens were obtained using a tenon cutter along the main trabecular load direction in the subchondral region of the femoral head. Additionally, thin bone slices were extracted proximal and distal to the specimens for density measurements. Brass plates were glued to the circular surfaces of the specimens. After curing of the adhesive, the specimens were mounted in the testing machine and destructive uniaxial compression tests were conducted. FINDINGS: The recorded mean compressive strengths and elastic moduli were almost identical for both groups, but the necrosis group showed significantly higher data scattering and range regarding the elastic modulus. The mean density of the coxarthrosis specimens was significantly higher than that of the necrotic specimens. INTERPRETATION: The mechanical properties of cancellous bone vary considerably in the presence of femoral head necrosis. The existence of hard necrosis implies a potential challenge regarding the clinical resection of these tissues.

Editorial Commentary: Cam Femoroacetabular Impingement Requires Dynamic Assessment of Beta-Angle (Femoroacetabular Excursion Angle) and Consideration of Femoral and Acetabular Version: Cam Impingement in Patients With Acetabular or Femoral Retroversion May Warrant Greater Osteoplasty.

Radiographs, magnetic resonance imaging, and computed tomography scans have been commonly used to evaluate femoroacetabular impingement (FAI) and are well accepted forms of surgical planning. Assessing and addressing both the femoral and acetabular sides result in a combination of "one-sided" treatments that, in sum, net a successful treatment of FAI. However, combining one-sided approaches may not consider the dynamic interaction of the femoral head with the acetabulum. Elevated alpha angles alone can be indicative of a cam-type lesion without necessitating the presence of functional FAI. The presence of a cam-type lesion on lateral radiographs, as suggested by a positive alpha angle, does not necessitate a decrease in clearance between the femoral head and acetabular rim as measured by the beta angle. Assessment of the beta angle, or femoroacetabular excursion angle, has the potential to address dynamic nature of FAI more accurately by directly measuring the degree of clearance between the femoral head and acetabulum. In addition, a comprehensive assessment of physical examination findings, particularly range of motion, as well as a summation of acetabular and femoral version (as measured by the McKibbin Index), are required. Cam-type of FAI poses a larger challenge in the patient with acetabular or femoral retroversion, which may warrant greater and more localized osteoplasty, distally, during hip arthroscopy.

[Visual and quantitative assessment of the effectiveness of non-vascularized bone grafting in osteonecrosis of the femoral head via CT-based radiomics and clinical data].

Objective: To investigate the value of CT-based radiomics and clinical data in predicting the efficacy of non-vascularized bone grafting (NVBG) in hip preservation, and to construct a visual, quantifiable, and effective method for decision-making of hip preservation. Methods: Between June 2009 and June 2019, 153 patients (182 hips) with osteonecrosis of the femoral head (ONFH) who underwent NVBG for hip preservation were included, and the training and testing sets were divided in a 7∶3 ratio to define hip preservation success or failure according to the 3-year postoperative follow-up. The radiomic features of the region of interest in the CT images were extracted, and the radiomics-scores were calculated by the linear weighting and coefficients of the radiomic features after dimensionality reduction. The clinical predictors were screened using univariate and multivariate Cox regression analysis. The radiomics model, clinical model, and clinical-radiomics (C-R) model were constructed respectively. Their predictive performance for the efficacy of hip preservation was compared in the training and testing sets, with evaluation indexes including area under the curve, C-Index, sensitivity, specificity, and calibration curve, etc. The best model was visualised using nomogram, and its clinical utility was assessed by decision curves. Results: At the 3-year postoperative follow-up, the cumulative survival rate of hip preservation was 70.33%. Continued exposure to risk factors postoperative and Japanese Investigation Committee (JIC) staging were clinical predictors of the efficacy of hip preservation, and 13 radiomic features derived from least absolute shrinkage and selection operator downscaling were used to calculate Rad-scores. The C-R model outperformed both the clinical and radiomics models in predicting the efficacy of hip preservation 1, 2, 3 years postoperative in both the training and testing sets ( P<0.05), with good agreement between the predicted and observed values. A nomogram constructed based on the C-R model showed that patients with lower Rad-scores, no further postoperative exposure to risk factors, and B or C1 types of JIC staging had a higher probability of femoral survival at 1, 2, 3 years postoperatively. The decision curve analysis showed that the C-R model had a higher total net benefit than both the clinical and radiomics models with a single predictor, and it could bring more net benefit to patients within a larger probability threshold. Conclusion: The prediction model and nomogram constructed by CT-based radiomics combined with clinical data is a visual, quantifiable, and effective method for decision-making of hip preservation, which can predict the efficacy of NVBG before surgery and has a high value of clinical application.

Morphometric assessment of the hip joint in children aged 2-13 years.

Our study aimed to evaluate the hip joints of healthy children aged 2-13 years morphometrically through radiographic images. Demographic characteristics of 300 healthy children in our study include an average age of 6.4 years old based on the 2-to-13-year-old bracket and sex classified to 133 girls and 167 boys. A total of 600 normal hips from these children were digitally measured based on Acetabular Index, ACM angle, MZ distance, Sharp angle, CE angle, Femoral Head Coverage Ratio, Cranial, and medial joint space (MJS). *p < 0.05; **p < 0.01 indicated a statistically significant difference. It was found that Acetabular Index, ACM angle, MZ distance, Sharp angle, Cranial, and MJSs decreased with age; Acetabular Depth value and CE angle increased with age; the CE angle differed between the sides (right-left) in the young teens period and in boys; and the cranial joint space (CJS) differed between the sides in girls. In addition, girls had higher values than boys in terms of Acetabular Index, ACM angle, Sharp angle, MZ distance, and Femoral Head Coverage Ratio; CE angle and MJS were higher in girls; and Acetabular Depth Value and CJS did not differ significantly between sexes. Obtaining the normal values will guide in the diagnosis and treatment of many clinical conditions including DDH and Legg-Calve-Perthes disease. It can also be used to compare the hips between healthy children and those diagnosed with Cerebral Palsy.

[Assessment of the local blood supply when femoral neck fracture occurs:advances in the anatomy research and its clinical application].

The stability of internal fixation of femoral neck fractures can be obtained through surgical techniques, the configuration of screws and bone grafting, etc. However, the blood supply injury caused by fractures could not be completely reversed by the current medical management. Hence, the comprehensive evaluation of the residual blood supply of the femoral neck, to perioperatively avoid further iatrogenic injury, has become a hotspot. The anatomy of the extraosseous blood supply of the femoral neck has been widely reported, while its clinical application mostly involved the assessment of the medial circumflex femoral artery and retinacular arteries. However, further studies are needed to explore the prognosis of patients with these artery injuries, with different degrees, caused by femoral neck fractures. Direct observations of nutrient foramina in vivo are not possible with current clinical technologies, but it is possible to make reasonable preoperative planning to avoid subsequent femoral head necrosis based on the distribution features of nutrient foramina. The anatomy and clinical application studies of the intraosseous blood supply focused on the junction area of the femoral head and neck to probe the mechanism of femoral head necrosis. Thus, the intraosseous blood supply of other regions in the femoral neck remains to be further investigated. In addition, a blood supply evaluation system based on a three-level structure, extraosseous blood vessels, nutrient foramina, and intraosseous vascular network, could be explored to assist in the treatment of femoral neck fractures.

MRI assessment of femoral head docking following closed reduction of developmental dysplasia of the hip.

AIMS: Eccentric reductions may become concentric through femoral head 'docking' (FHD) following closed reduction (CR) for developmental dysplasia of the hip (DDH). However, changes regarding position and morphology through FHD are not well understood. We aimed to assess these changes using serial MRI. METHODS: We reviewed 103 patients with DDH successfully treated by CR and spica casting in a single institution between January 2016 and December 2020. MRI was routinely performed immediately after CR and at the end of each cast. Using MRI, we described the labrum-acetabular cartilage complex (LACC) morphology, and measured the femoral head to triradiate cartilage distance (FTD) on the midcoronal section. A total of 13 hips with initial complete reduction (i.e. FTD < 1 mm) and ten hips with incomplete MRI follow-up were excluded. A total of 86 patients (92 hips) with a FTD > 1 mm were included in the analysis. RESULTS: At the end of the first cast period, 73 hips (79.3%) had a FTD < 1 mm. Multiple regression analysis showed that FTD (p = 0.011) and immobilization duration (p = 0.028) were associated with complete reduction. At the end of the second cast period, all 92 hips achieved complete reduction. The LACC on initial MRI was inverted in 69 hips (75.0%), partly inverted in 16 hips (17.4%), and everted in seven hips (7.6%). The LACC became everted-congruent in 45 hips (48.9%) and 92 hips (100%) at the end of the first and second cast period, respectively. However, a residual inverted labrum was present in 50/85 hips (58.8%) with an initial inverted or partly inverted LACC. CONCLUSION: An eccentric reduction can become concentric after complete reduction and LACC remodelling following CR for DDH. Varying immobilization durations were required for achieving complete reduction. A residual inverted labrum was present in more than half of all hips after LACC remodelling.Cite this article: Bone Joint J 2023;105-B(2):140-147.

The influence of bone marrow edema for the assessment of the boundaries of necrotic lesions in patients with osteonecrosis of the femoral head.

This study aimed to investigate the influence of bone marrow edema (BME) for the assessment of the boundaries of necrotic lesions using unenhanced and contrast-enhanced (CE) magnetic resonance (MR) images in patients with osteonecrosis of the femoral head (ONFH). We retrospectively reviewed 72 consecutive hips in 55 patients of ONFH that were Association Research Circulation Osseous (ARCO) stage III or higher and underwent both unenhanced and contrast-enhanced MR imaging between January 2005 and February 2016. The degree of extension of BMEs, and the boundaries of the necrotic lesions were compared using unenhanced and CE MR images on both mid coronal and mid oblique-axial slices. Forty-two percent of the coronal T1 images, 40% of the coronal fat-saturated T2 images, and 48% of the oblique-axial T1 images showed differences in the boundaries of necrotic lesion, by comparison with those of CET1-weighted MR images. The boundaries of necrotic lesions were clearly detected in all hips on CE coronal slices and 97% of all hips on CE oblique-axial slices. The BME grade in the difference group was significantly higher than in the non-difference group on the coronal plane (P = 0.0058). There were significant differences between the BME grade and duration from the onset of hip pain to MR imaging examination. Multivariate analyses revealed that the duration from the onset to MR imaging examination in both coronal (P = 0.0008) and oblique-axial slices (P = 0.0143) were independently associated with differences in the boundary of necrotic lesion between T1 and CET1-weighted MR images. Our findings suggest that unenhanced MR image may be insufficient for a precise assessment of the boundaries of the necrotic lesions for ONFH cases in the early phase of subchondral collapse due to the diffuse BME.

Prediction of collapse in femoral head osteonecrosis: role of volumetric assessment.

PURPOSE: The purpose of this study was to evaluate and compare the accuracy of three different techniques of measuring the extent of osteonecrosis involvement of the femoral head on MRI to determine the best predictor of collapse and to identify the size of the lesion volume which best predicts collapse. METHODS: We prospectively enrolled 48 hips of osteonecrosis femoral head (ONFH) with stage 1 or 2 osteonecrosis and the enrolled patients were followed up for 1 year. Angular measurements (modified Kerboul Angle and modified index of necrotic extent) were compared with the 3D volumetric measurement of necrotic lesion based on MRI in predicting the collapse of the head. ROC analysis was done to evaluate the diagnostic performance of the 3 indices in predicting collapse. Survival analysis of all the hips in the collapsed and non-collapsed group were interpreted using Kaplan Meir survival analysis. RESULTS: In lesion sizes larger than 25% of femoral head volume - 90.6% (29/32) of hips collapsed within 1 year as compared to 31.3% (5/16) hips collapsed in lesion volume <25% of femoral head (Log-rank test p = 0.001). There was good inter-observer (ICC, 0.94; 95% CI, 0.89-0.97) and intra-observer reliability (ICC, 0.93; 95% CI, 0.88-0.96). CONCLUSIONS: The Volumetric method assessed the severity of lesion size with the future collapse better and more predictably than angular measurements. Necrotic lesion volume of 25% is a potential cut off beyond which future collapse of early ONFH can be predicted and aid in the further management. This study can help in solving the mystery behind prediction of collapse in ONFH.

Editorial Commentary: Not Yet Convinced That the Femoroacetabular Impingement Resection (Fair) Arc Measurement Provides a "Fair" Assessment of Cam Resection Principles.

Hip arthroscopy has proven to be an effective surgical approach for the treatment of femoroacetabular impingement (FAI) syndrome. Studies have shown that patients typically have improved functional outcomes and high rates of return to activity following cam lesion resection and reshaping of the femoral head-neck junction. However, despite these favorable outcomes, there is still a steep and well-recognized learning curve in FAI hip arthroscopy. Although it is common dogma to consider an ideal reshaping of the femoral head-neck junction as being perfectly spherical, the ability to achieve this intraoperatively can be quite challenging. A new tool is the "femoroacetabular impingement resection (FAIR) arc," measured on a 45° Dunn lateral radiograph where a best-fit circle incorporates the region immediately inferior to the anteroinferior iliac spine, the subspine region, and lateral femoral neck base. The maximal radial distance height is then measured from the circumference of this circle to the apex of the cam lesion. This radiographic aid may assist with intraoperative estimate of appropriate cam lesion resection depth. While I tend to utilize preoperative radiographs and intra-operative neck sclerosis to determine cam resection depth, I continue to seek out other ways to effectively perform a femoral osteoplasty. While my initial attempt to utilize the FAIR index in my practice did not seem effective, I will continue to test this measurement in my patients.

Comparison of magnetic resonance imaging and computed tomography for bone assessment of neurogenic heterotopic ossification of the hip: a preliminary study.

BACKGROUND: Neurogenic heterotopic ossification (NHO) is a frequent complication, often involving the hip. The functional impact may require surgical management and pre-surgical imaging assessment is necessary, usually by computed tomography (CT). We aimed to compare the performances of magnetic resonance imaging (MRI) and CT for bone assessment on pre-surgical imaging of the heterotopic ossifications and their features in NHO of the hip. METHODS: This single-center prospective preliminary study included all patients who underwent surgery for NHO with joint limitation from July 2019 to March 2020. All patients had a CT after biphasic iodinated solution injection and an MRI including T1-weighted, STIR and ZTE sequences. Standardized reports were completed for both exams for each patient, evaluating location, implantation and fragmentation of NHO, relation to the joint capsule and bone mineralization, then were compared. RESULTS: Seven patients from 32 to 70 years old (mean = 50.2 ± 17.2 years) were evaluated. NHO were bilateral in 2 patients, for a total of nine hips: six right hips and three left hips. Observed concordance rates between MRI and CT were, respectively, 94.4% for location, 100% for circumferential extension, 87.3% for implantation 88.9% for fragmentation, 77.8% for relation to the joint capsule and 66.7% for bone mineralization. It was 100% for femoral neck fracture and osteonecrosis of the femoral head. CONCLUSION: This preliminary study suggests that pre-surgical MRI imaging should be considered as effective as CT for bone assessment of NHO and their features. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03832556. Registered February 6, 2019, https://clinicaltrials.gov/ct2/show/NCT03832556 .

Assessment of coxarthritis risk with dimensionless biomechanical parameters.

PURPOSE: Unfavourable distribution of contact stress over the load bearing area is considered a risk factor for early coxarthritis and it is of interest to outline respective biomechanical parameters for its prediction. The purpose of the work was to develop a transparent mathematical model which can be used to assess contact stress in the hip from imaged structures of pelvis and proximal femora, in large population studies and in clinical practice. METHODS: We upgraded a previously validated three-dimensional mathematical model of the human hip in the one-legged stance HIPSTRESS by introducing parameters independent from the size of the structures in the images. We validated a new parameter - dimensionless peak stress normalized by the body weight and by the radius of the femoral head (pmaxr²/WB) on the population of 172 hips that were in the childhood subjected to the Perthes disease and exhibited increased proportion of dysplastic hips. RESULTS: The dimensionless parameter pmaxr²/WB exhibited smaller number of indecisive cases of hip dysplasia predicted by the model than the previously used parameter pmax/WB (6% vs. 81%, respectively). A threshold for an increased risk of early coxarthritis development by the HIPSTRESS parameter H = pmaxr²/WB was found to be 2. CONCLUSIONS: We proposed a dimensionless peak stress on the load bearing area with the border value of 2 as a decisive parameter over which hips are at risk for early development of degenerative processes and presented a method for determination of biomechanical parameters with the use of nomogram.

[Clinical study on new risk assessment and prediction system for early osteonecrosis of the femoral head].

OBJECTIVE: To establish a risk assessment and prediction system for early osteonecrosis of the femoral head (ONFH) in order to predict the collapse risk. METHODS: The risk assessment system for early necrosis and collapse of femoral head was established based on the combination of Steinberg stage, ABC typing and the proportion of the proximal sclerotic rim. Firstly, Steinberg stage system was applied. ABC typing was applied to predict risk in stage I, type C was risk free, type B was low risk, type A and type BC were medium risk, type A-C and type AB were high risk. The classification of proximal sclerotic rim was first applied when the Steinberg stage was Ⅱ-Ⅲ, and type 2 was expected to be low risk. If the classification of proximal sclerotic rimwas type 1, then the ABC typing was applied, type C was risk-free, type B was low risk, type A and type BC were medium risk, type A-C and type AB were high risk. According to this prediction system, the collapse risk of femoral head in 188 cases(301 hips) were predicted by retrospective analysis. All the hips were enrolled at the out-patient department of orthopedic in Guang'anmen Hospital attached to China Academy of Chinese Medical Science. The consistency of the prediction results of three doctors and one doctor at different times were evaluated. RESULTS: Among them, 136 cases were male, 52 were female. 75 cases were single hip, 113 were double hip. The age of the patients wa 19 to 64(42.61±12.07) years. The natural course of disease was 0.33 to 5.00(3.62±1.93) years. 206 hips in 301 hips had collapsed, with a collapse rate of 68.44%. In the risk-free group, none hip had collapsed, with a collapse rate of 0%. In the low-risk group, 9 hip in 91 hips had collapsed, with a collapse rate of 9.89%. In the medium-risk group, 12 hip in 19 hips had collapsed, with a collapse rate of 63.16%. And in the high risk group, 185 hips in 190 hips had collapsed, with a collapse rate of 97.37%. They were significantly differences in their collapse rate (P=0.00) in the following order:high-risk group> medium-risk > low-risk group > risk-free group. The prediction value of the system was high (AUC=0.95, P=0.00). The results predicted by different doctors were consistent (ICC=0.94, P=0.00), and the results predicted by the same doctor at two different times were consistent (Kappa coefficient =0.90, P=0.00). CONCLUSION: The risk assessment and prediction system for early ONFH selects different methods to predict the risk of collapse according to the imaging characteristics of different stages, which is combines with the comprehensive assessment of multiple risk factors. The system is applicable to a wide range, simple operation and convenient for clinical application.

Medialization of the Hip's Center with Periacetabular Osteotomy: Validation of Assessment with Plain Radiographs.

BACKGROUND: Periacetabular osteotomy (PAO) increases acetabular coverage of the femoral head and medializes the hip's center, restoring normal joint biomechanics. Past studies have reported data regarding the degree of medialization achieved by PAO, but measurement of medialization has never been validated through a comparison of imaging modalities or measurement techniques. The ilioischial line appears to be altered by PAO and may be better visualized at the level of the inferior one-third of the femoral head, thus, an alternative method of measuring medialization that begins at the inferior one-third of the femoral head may be beneficial. QUESTIONS/PURPOSES: (1) What is the true amount and variability of medialization of the hip's center that is achieved with PAO? (2) Which radiographic factors (such as lateral center-edge angle [LCEA] and acetabular inclination [AI]) correlate with the degree of medialization achieved? (3) Does measurement of medialization on plain radiographs at the center of the femoral head (traditional method) or inferior one-third of the femoral head (alternative method) better correlate with true medialization? (4) Are intraoperative fluoroscopy images different than postoperative radiographs for measuring hip medialization? METHODS: We performed a retrospective study using a previously established cohort of patients who underwent low-dose CT after PAO. Inclusion criteria for this study included PAO as indicated for symptomatic acetabular dysplasia, preoperative CT scan, and follow-up between 9 months and 5 years. A total of 333 patients who underwent PAO from February 2009 to July 2018 met these criteria. Additionally, only patients who were between 16 and 50 years old at the time of surgery were included. Exclusion criteria included prior ipsilateral surgery, femoroacetabular impingement (FAI), pregnancy, neuromuscular disorder, Perthes-like deformity, inadequate preoperative CT, and inability to participate. Thirty-nine hips in 39 patients were included in the final study group; 87% (34 of 39) were in female patients and 13% (5 of 39 hips) were in male patients. The median (range) age at the time of surgery was 27 years (16 to 49). Low-dose CT images were obtained preoperatively and at the time of enrollment postoperatively; we also obtained preoperative and postoperative radiographs and intraoperative fluoroscopic images. The LCEA and AI were assessed on plain radiographs. Hip medialization was assessed on all imaging modalities by an independent, blinded assessor. On plain radiographs, the traditional and alternative methods of measuring hip medialization were used. Subgroups of good and fair radiographs, which were determined by the amount of pelvic rotation that was visible, were used for subgroup analyses. To answer our first question, medialization of all hips was assessed via measurements made on three-dimensional (3-D) CT hip reconstruction models. For our second question, Pearson correlation coefficients, one-way ANOVA, and the Student t-test were calculated to assess the correlation between radiographic parameters (such as LCEA and AI) and the amount of medialization achieved. For our third question, statistical analyses were performed that included a linear regression analysis to determine the correlation between the two radiographic methods of measuring medialization and the true medialization on CT using Pearson correlation coefficients, as well as 95% confidence intervals and standard error of the estimate. For our fourth question, Pearson correlation coefficients were calculated to determine whether using intraoperative fluoroscopy to make medialization measurements differs from measurements made on radiographs. RESULTS: The true amount of medialization of the hip center achieved by PAO in our study as assessed by reference-standard CT measurements was 4 ± 3 mm; 46% (18 of 39 hips) were medialized 0 to 5 mm, 36% (14 hips) were medialized 5 to 10 mm, and 5% (2 hips) were medialized greater than 10 mm. Thirteen percent (5 hips) were lateralized (medialized < 0 mm). There were small differences in medialization between LCEA subgroups (6 ± 3 mm for an LCEA of ≤ 15°, 4 ± 4 mm for an LCEA between 15° and 20°, and 2 ± 3 mm for an LCEA of 20° to 25° [p = 0.04]). Hips with AI ≥ 15° (6 ± 3 mm) achieved greater amounts of medialization than did hips with AI of < 15° (2 ± 3 mm; p < 0.001). Measurement of medialization on plain radiographs at the center of the femoral head (traditional method) had a weaker correlation than using the inferior one-third of the femoral head (alternative method) when compared with CT scan measurements, which were used as the reference standard. The traditional method was not correlated across all radiographs or only good radiographs (r = 0.16 [95% CI -0.17 to 0.45]; p = 0.34 and r = 0.26 [95% CI -0.06 to 0.53]; p = 0.30), whereas the alternative method had strong and very strong correlations when assessed across all radiographs and only good radiographs, respectively (r = 0.71 [95% CI 0.51 to 0.84]; p < 0.001 and r = 0.80 [95% CI 0.64 to 0.89]; p < 0.001). Measurements of hip medialization made on intraoperative fluoroscopic images were not found to be different than measurements made on postoperative radiographs (r = 0.85; p < 0.001 across all hips and r = 0.90; p < 0.001 across only good radiographs). CONCLUSION: Using measurements made on preoperative and postoperative CT, the current study demonstrates a mean true medialization achieved by PAO of 4 mm but with substantial variability. The traditional method of measuring medialization at the center of the femoral head may not be accurate; the alternate method of measuring medialization at the lower one-third of the femoral head is a superior way of assessing the hip center's location. We suggest transitioning to using this alternative method to obtain the best clinical and research data, with the realization that both methods using plain radiography appear to underestimate the true amount of medialization achieved with PAO. Lastly, this study provides evidence that the hip center's location and medialization can be accurately assessed intraoperatively using fluoroscopy. LEVEL OF EVIDENCE: Level III, diagnostic study.

Management of Morbidity and Mortality in a New Zealand White Rabbit Model of SteroidInduced Osteonecrosis of the Femoral Head.

Steroid-induced osteonecrosis of the femoral head (SONFH) is a condition documented in humans and animals exposed to chronic steroid administration. The rabbit has become a preferred animal model for investigating the pathogenesis and treatment of SONFH due to its shared femoral vascular anatomy with human patients, relative size of the femoral head, and general fecundity. However, morbidity and mortality are frequent during the steroid induction period, prior to surgical manipulation. These problems are poorly reported and inadequately described in the literature. In this study, we report the clinical, gross, and histopathologic findings of New Zealand white (NZW) rabbits undergoing the steroid induction phase of the SONFH model. Severe weight loss (>30%), lipemia, hypercholesterolemia, hyperglycemia, and elevations in ALT and AST were consistent findings across all rabbits, although these changes did not differentiate asymptomatic rabbits from those that became clinically symptomatic or died. Euthanized and spontaneously deceased rabbits exhibited hepatomegaly, hepatic lipidosis/glycogenosis, and hepatocellular necrosis, in addition to a lipid-rich and proteinaceous thoracic effusion. A subset of rabbits developed opportunistic pulmonary infections with Bordetella bronchiseptica and Escherichia coli and small intestine infections with Lawsonia intracellularis superimposed on hepatic and thoracic disease. Together, these findings allowed us to establish a clinical decision-making flowchart that reduced morbidities and mortalities in a subsequent cohort of SONFH rabbits. Recognition of these model-associated morbidities is critical for providing optimal clinical care during the disease induction phase of SONFH.

Assessment of the young adult hip joint using plain radiographs.

Radiographic examination remains the mainstay of the initial assessment of the young adult hip; however, common parameters are required to assist in the formation of accurate diagnoses and appropriate management plans. This paper aims to summarise the most important aspects of the assessment of plain radiographs performed on the young adult hip joint.