Cross-table Lateral Radiographs Research Articles

QUANTIFYING RADIATION EXPOSURE IN THE RADIOLOGICAL INVESTIGATION OF NON-ARTHRITIC HIP PAIN

Radiological investigations are essential in the work-up of patients presenting with non-arthritic hip pain, to allow close review of the complex anatomy around the hip and proximal femur. The aim of this study is to quantify the radiation exposure associated with common radiological investigations performed in assessing young adult patients presenting with non-arthritic hip pain.A retrospective review of our UK tertiary hip preservation centre institutional imaging database was performed. Data was obtained for antero-posterior, cross-table lateral and frog-lateral radiographs, along with data for the low dose CT hip protocol and the Mako CT Hip protocol. The radiation dose of each imaging technique was measured in terms of dose-area product (DAP) with units of mGycm2, and the effective doses (ED, mSv) calculated.The mean effective radiation dose for hip radiographs was in the range 0.03 to 0.83mSv (mean DLP 126.7–156.2 mGycm2). The mean effective dose associated with the low-dose CT hip protocol was 3.04mSv (416.8 mGycm2) and for the Stryker Mako CT Hip protocol was 8.4mSv (1061 mGycm2). The radiation dose associated with use of CT imaging was significantly greater than plain radiographs (p<0.005)Investigation of non-arthritic hip pain can lead to significant ionising radiation exposure for patients. In our institution, the routine protocol is to obtain an anteroposterior radiograph and then a specific hip sequence 3 Tesla MRI including anteversion views. This provides the necessary information in the majority of cases, with CT scanning reserved for more complex cases where we feel there is a specific indication. We would encourage the hip preservation community to carefully consider and review the use of ionising radiation investigations.

Could We Expect Postoperative Cup Anteversion after Total Hip Arthroplasty Using Postoperative Plain Anteroposterior and Lateral Radiograph? A Three-Dimensional Experimental Operation Study.

A postoperative radiograph in total hip arthroplasty (THA) is usually obtained to evaluate the inclination and anteversion of the acetabular components. However, there is no gold-standard method for calculating the exact inclination and anteversion of the acetabular components on post-THA radiographs. We aimed to measure the actual anteversion of the acetabular component on postoperative radiographs by obtaining correlation data between the virtual and actual acetabular component positioning using virtual three-dimensional (3D) surgery. A total of 64 hip scans of 32 patients who underwent lower-extremity computed tomography (CT) were retrospectively reviewed. We reconstructed 3D models of the 64 hips using customized computer software (Mimics). Furthermore, to identify the safe zone of acetabular component position in THA, we performed virtual 3D surgery simulations for five anteversion (-10°, 0°, 10°, 20°, and 30°) and five inclination (20°, 30°, 40°, 50°, and 60°) types. We analyzed the acetabular anatomy using 3D models to measure the radiographic, anatomical, and operative anteversion (RA, AA, OA) and inclination (RI, AI, OI) angles. Additionally, we used the Woo-Morrey (WM) method to calculate the anteversion angle in the reconstructed cross-table lateral (CL) radiographs and determined the correlation between these measurements. The safe zone of the acetabular component was visualized on post-THA CL radiographs using the WM method of anteversion measurement based on the different anteversions and inclinations of the acetabular component. The AA, RA, OA, OI, and WM differed significantly between males and females (p value < 0.05). As the anatomical inclination or anteversion increased, the WM anteversion measurements also increased. The radiographic anteversion measurement best matched the WM method of measurement, followed by anatomical and operative methods. The actual anteversion of the acetabular component after THA can be measured on CL radiographs with the WM method using a 3D virtual program, with good reproducibility.

MRI Does Not Improve Inter- or Intrarater Reliability for Hip Arthritis Grading Systems

Background: Magnetic resonance imaging (MRI) scans and radiographs are often utilized in assessing for preoperative osteoarthritis in patients undergoing hip preservation surgery. Purpose: To determine if MRI scans improve inter- or intrarater reliabilities over radiographs for findings of hip arthritis. Study Design: Cohort study (Diagnosis); Level of evidence, 3. Methods: Anteroposterior and cross-table lateral radiographs as well as a representative coronal and sagittal T2-weighted MRI scan were reviewed for 50 patients by 7 experienced subspecialty hip preservation surgeons, with a minimum experience of 10 years. Radiographs and MRI scans were assessed for joint space narrowing, subchondral cysts, osteophytes, subchondral sclerosis, Likert osteoarthritis grade (none, mild, moderate, or severe), and Tönnis grade. MRI scans were also evaluated for bony edema, heterogeneous articular cartilage, and chondral defects. Inter- and intrarater reliabilities were calculated utilizing the Fleiss method with a 95% CI. Results: The scans of 50 patients (28 female and 22 male) with a mean age of 42.8 years (SD, 14.2 years; range, 19-70 years) were reviewed. Radiographs revealed fair agreement for joint space narrowing (κ = 0.25 [95% CI, 0.21-0.30]), osteophytes (κ = 0.26 [95% CI, 0.14-0.40]), Likert osteoarthritis grading (κ = 0.33 [95% CI, 0.28-0.37]) and Tönnis grade (κ = 0.30 [95% CI, 0.26-0.34). Radiographs revealed moderate agreement for subchondral cysts (κ = 0.53 [95% CI, 0.35-0.69]). MRI scans demonstrated poor to fair agreement for joint space narrowing (κ = 0.15 [95% CI, 0.09-0.21]), subchondral sclerosis (κ = 0.27 [0.19-0.34]), heterogeneous articular cartilage (κ = 0.07 [95% CI, 0.00-0.14]), Likert osteoarthritis grade (κ = 0.19 [95% CI, 0.15-0.24]), and Tönnis grade (κ = 0.20 [95% CI, 0.15-0.24]). MRI scans demonstrated substantial agreement for subchondral cysts (κ = 0.73 [95% CI, 0.63-0.83]). Intrarater reliabilities were statistically improved compared with interrater reliabilities, but no differences were found between radiographs and MRI scans for joint space narrowing, subchondral cysts, osteophytes, osteoarthritis grade, or Tönnis grade. Conclusion: Radiographs and MRI scans had substantial limitations and inconsistency between raters in evaluating common markers of hip osteoarthritis. MRI scans demonstrated strong reliability in evaluating for subchondral cysts but did not improve the interobserver variability of grading hip arthritis.

A novel method for evaluating combined component anteversion in total hip arthroplasty on cross-table lateral hip radiographs

IntroductionAccurate measurement of combined component anteversion (CA) is important in evaluating the radiographic outcomes following total hip arthroplasty (THA). The aim of the present study was to evaluate the accuracy and reliability of a novel radiographic method in estimating CA in THA.Materials and methodsThe radiographs and computer tomography of patients who underwent a primary THA were retrospectively reviewed, to measure the radiographic CA (CAr), defined as the angle between a line connecting the center of the femoral head to the most anterior rim of the acetabular cup and a line connecting the center of the femoral head to the base of the femoral head to allow a comparison with the CA measured on the CT (CACT). Subsequently, a computational simulation was performed to evaluate the effect of cup anteversion, inclination, stem anteversion, and leg rotation on the CAr and develop a formula that would correct the CAr according to the acetabular cup inclination based on the best-fit equation.ResultsIn the retrospective analysis of 154 THA, the average CAr_cor, and CACT were 53 ± 11° and 54 ± 11° (p > 0.05), respectively. A strong correlation was found between CAr and CACT (r = 0.96, p < 0.001), with an average bias of − 0.5° between CAr_cor and CACT. In the computational simulation, the CAr was strongly affected by the cup anteversion, inclination, stem anteversion, and leg rotation. The formula to convert the CAr to CA_cor was: CA-cor = 1.3*Car − (17* In (Cup Inclination) − 31.ConclusionThe combined anteversion measurement of THA components on the lateral hip radiograph is accurate and reliable, implying that it could be routinely used postoperatively but also in patients with persistent complaints following a THA.Level of evidenceCross-sectional study, Level III.

Effect of surgical approach on functional outcome and component positioning in total hip arthroplasty

Context: Total hip arthroplasty (THA) is commonly performed through a posterior or a direct lateral (Hardinge) approach, and each one has merits and demerits. Aims: The purpose of this study was to examine the difference between the lateral and posterior approaches with respect to functional outcome, component positioning, intraoperative blood loss, and patient satisfaction. Settings and Design: This is a prospective comparative study of short- to mid-term outcome of cementless THA using two approaches. Subjects and Methods: Seventy hips satisfying our inclusion criteria were selected, of which 21 hips operated by lateral approach in supine position were included in lateral approach group (LAG), and 49 hips operated by posterior approach in lateral position were included in posterior approach group (PAG). Functional assessment was performed 1 day before surgery, 1 year after surgery, and at the latest follow-up using Harris Hip score (HHS). Component positioning of acetabular cup and femoral stem was assessed in plain radiographs at the latest follow-up. Generic satisfaction questionnaire was used to measure satisfaction after THA at the latest follow-up. Radiographic measurements (cup inclination, cup version, and femoral stem tip position) were performed postoperatively using low-centered pelvic anteroposterior and cross-table lateral hip radiographs. Results: At an average of 3 years and 6 months of follow-up, the mean HHSs were 88.05 and 90.32, respectively, in LAG and PAG; the difference was not significant (P = 0.178). The average inclination of the cup in LAG was 37.9° and in PAG was 45.02° with a significant difference (P = 0.00027), both of which are in the normal range. The cups were significantly (P ≤ 0.0001) more anteverted in the PAG (average angle of 27.69° vs. 16.14°). The mean blood loss was significantly more in PAG (510 ml vs. 436.67 ml; P = 0.04). Majority of femoral stems in lateral approach had their tips directed posterior. Nineteen out of 21 LAG patients and 45 out of 49 PAG were very satisfied/satisfied with their outcomes after THA. Statistical Analysis Used: Data were collected using prestructured data forms and analyzed with unpaired Student's t-test with 95% confidence interval. Conclusions: There was no significant difference in functional outcome and patient satisfaction at short- to mid-term follow-up between both approaches. The cup anteversion was significantly more in PAG. For better conclusions, other factors (i.e. immediate postoperative pain, and long-term survival), combined anteversion and spinopelvic parameters, have to be included in the study with a larger sample size.

Stripe Wear - Ceramic on Polyethylene Bearing Surface: A Case Report

Background: Stripe wear is a well-known phenomenon that might be caused by rim impingement, edge loading, metal particle entrapment, micro-separation, and transient subluxation. Stripe wear is felt to represent metal transfer and has been associated with squeaking in ceramic-on-ceramic bearings. In our paper, we report the presence of stripe wear on a retrieved modular ceramic femoral head from a patient with ceramic-on-polyethylene-bearing total hip arthroplasty. Method: We report a case of a 57-year-old male who originally had metal-on-metal (MOM) THA and underwent debridement and exchange of the bearing surface from MOM to ceramic-on-polyethylene (COP) articulation for pain and metallosis. He subsequently developed sepsis and underwent resection arthroplasty. Result: Intraoperatively, a cross-table lateral radiograph revealed the forward flexion of the acetabular component and femoral neck to posterior acetabular margin impingement. By analyzing the retrieved components macroscopically and microscopically, linear scars were found on the polyethylene liner, femoral neck, and femoral head in a pattern consistent with the X-ray finding. Conclusion: If metallosis is encountered after THA, the source of the metal wear should be identified. Component malposition is a possible cause, and the surgeon should consider revision or repositioning of the components if evidence of impingement is seen, as a simple bearing exchange may not solve the problem. This report indicates that stripe wear is not limited to ceramic on ceramic articulations.

Ultrasound-Guided Iliopsoas Bursal Injections for Management of Iliopsoas Bursitis After Total Hip Arthroplasty

BackgroundIliopsoas tendonitis can cause persistent pain after total hip arthroplasty (THA). Nonoperative management of iliopsoas tendonitis includes anti-inflammatory drugs and image-guided corticosteroid injections. This study evaluated the efficacy of ultrasound-guided corticosteroid injections (US-CSIs) for iliopsoas tendonitis following THA. MethodsWe retrospectively reviewed 42 patients who received an US-CSI for iliopsoas tendonitis after primary THA between 2009 and 2020 at a single institution. Outcomes including reoperation, groin pain at last follow-up, additional intrabursal injection, and Harris Hip Score (HHS) were evaluated at a minimum of 1 year. Cross-table lateral radiographs (36 patients) or computed tomography scans (6 patients) were reviewed to determine if anterior cup overhang was present, indicating a mechanical etiology of iliopsoas tendonitis. Descriptive statistics and univariate comparison of HHS preinjection and postinjection were performed, with alpha < 0.05. ResultsAmong the 22 patients who did not have cup overhang, four (18.2%) had persistent groin pain at mean follow-up of 40 months (range, 14-94) after US-CSI. Three patients had a second injection; none had groin pain at most recent follow-up. No patients required acetabular revision. Mean HHS improved from 74 points (range, 52-94 points) to 91 points (range, 76-100 points; P < .001) at last follow-up. Among the 20 patients who had anterior cup overhang, five underwent acetabular revision after only temporary pain relief from injection. Groin pain was resolved in all revised patients at mean follow-up of 43 months (range, 12-60) after revision. Of the remaining 15 patients, five had persistent groin pain at mean follow-up of 35 months (range, 12-83). Mean HHS improved from 69 points (range, 50-96 points) preinjection to 81 (range, 56-98 points; P = .007) at last follow-up. ConclusionResolution of groin pain was demonstrated in 78.6% of patients in the cohort; however, those who did not have acetabular overhang had higher rates of success. The overall revision rate was 11.9%. US-CSI appears to be safe and effective in the diagnosis and treatment of iliopsoas tendonitis following primary THA. Level of EvidenceLevel IV, Therapeutic Study.

Reliability and Validity of Standing Lateral Radiograph Method for Measuring Acetabular Component Version: A Modified Cross-table Lateral Radiograph Method.

ObjectivesTo investigate the effect of the X‐ray incidence angle on cup version measurements and the reliability and validity of standing lateral (SL) radiography for measuring cup versions.MethodsCup versions under different X‐ray incidence angles were investigated by the 3D simulation analysis. Ninety‐three patients, who underwent primary total hip arthroplasty (THA) with postoperative SL radiographs and CT scans between April 2020 and December 2021, were retrospectively analyzed. SL radiography was taken under naturally standing position, correcting for the measurement error of pelvic tilt in cross‐table lateral (CL) radiography. Cup versions were measured on SL radiographs and CT images by two qualified orthopedic physicians. The intra‐ and inter‐observer reliabilities were assessed by intra‐class correlation coefficient. The consistency between radiographic and CT measurements was evaluated using Pearson correlation coefficient.ResultsNo significant differences in cup version measurements were observed between groups of different X‐ray incidence angles (P = 0.663) in the 3D simulation analysis. All measurements had excellent intra‐ and inter‐observer reliabilities, with an intraclass correlation coefficient of >0.95. Mean cup version measurements from SL radiographs correlated well with those from CT scans (r = 0.853, P < 0.001). The mean difference between radiographic and CT measurements was −0.49° (range −12.62° to 10.37°, SD 3.95°), and the majority of differences were within the 95% limits of agreement.ConclusionThe cup versions measured with SL radiography were close to the CT measurements. SL radiograph method is reliable and valid for measuring acetabular component version after THA.

Radiological comparison of acetabular anteversion on cross-table lateral roentgenograms and computed tomograms functional outcomes in total hip arthroplasty

Introduction: Orientation and Alignment of prosthetic components are vitally important for the stability of total hip arthroplasty. Poor acetabular positioning is one of the many issues implicated with persistent pain due to impingement, dislocation, edge loading and liner fracture, which may be lead to patient dissatisfaction after total hip arthroplasty. Material and methods: Post-operative radiological analysis of the version of acetabulum through X-ray images and CT images was performed. Pre & post-operative scoring according to Modified Harris Hip Score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Oxford Hip Score (OHS) was documented. Results: A total of 55 patients were included in the study. The mean anteversion angle calculated on cross-table lateral radiograph by Woo and Morrey's method was 22.410 (Range 16-560), compared to CT Scans measured was 28.640 (Range 11.10-50.100). Conclusion: Majority 69.09 % of patients had excellent functional outcomes in a range of 11.1-360 of anteversion compared to Lewinnek’s safe zone. It suggests that there is flexibility in positioning the acetabular component than previously believed. If one has to err, it should be towards more anteversion. Infact to avoid dislocation, more anteversion is required to guard against unwarranted activities on part of the patient.

Radiological comparison of acetabular anteversion on roentgenograms and computed tomograms functional outcomes in total hip arthroplasty

Introduction: Orientation and Alignment of prosthetic components are vitally important for the stability of total hip arthroplasty. Poor acetabular positioning is one of the many issues implicated with persistent pain due to impingement, dislocation, edge loading and liner fracture, which may be lead to patient dissatisfaction after total hip arthroplasty. Material and methods: Post-operative radiological analysis of the version of acetabulum through X-ray images and CT images was performed. Pre & post-operative scoring according to Modified Harris Hip Score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Oxford Hip Score (OHS) was documented. Results: A total of 55 patients were included in the study. The mean anteversion angle calculated on anteroposterior (AP) radiographs by Lewinnek’s method was 23.480 (Range 11 – 390) and on cross-table lateral radiograph by Woo and Morrey's method was 22.410 (Range16 – 560), compared to CT Scans measured was 28.640 (Range 11.10 – 50.100). Conclusion: Majority 69.09% of patients had excellent functional outcomes in a range of 11.1 – 360 of anteversion compared to Lewinnek’s safe zone. It suggests that there is flexibility in positioning the acetabular component than previously believed. If one has to err, it should be towards more anteversion. Infact to avoid dislocation, more anteversion is required to guard against unwarranted activities on part of the patient.

The Role of Imaging in Femoroacetabular Impingement: History, Current Practices, and Future Applications.

Femoroacetabular impingement (FAI) is one of the most common causes of early hip articular cartilage wear and labral damage, and subsequently leads to the onset of hip osteoarthritis. Cam-type FAI impingement lesions can be best identified with a 90° Dunn lateral radiograph and a cross-table lateral radiograph with 15° of internal rotation; the alpha angle and the femoral head-neck offset are the most used predictive radiographic markers. FAI lesions with pincer impingement are associated with acetabular retroversion and are more difficult to identify on traditional radiographic imaging; however, the presence of a crossover sign, an ischial spine sign, and/or a posterior wall sign can be useful radiographic markers. Advanced imaging modalities such as magnetic resonance imaging (MRI) and/or magnetic resonance arthrography (MRA) can also be beneficial in the evaluation of FAI and labral pathology; MRA is more sensitive than MRI in detecting intra-articular pathology. Computer-assisted navigation for preoperative planning and intraoperative surgical assistance are promising technologies; however, additional studies are needed before they can be utilized safely and effectively.

Spinopelvic mobility affects accuracy of acetabular anteversion measurements on cross-table lateral radiographs.

Cross-table lateral (CTL) radiographs are commonly used to measure acetabular component anteversion after total hip arthroplasty (THA). The CTL measurements may differ by > 10° from CT scan measurements but the reasons for this discrepancy are poorly understood. Anteversion measurements from CTL radiographs and CT scans are compared to identify spinopelvic parameters predictive of inaccuracy. THA patients (n = 47; 27 males, 20 females; mean age 62.9 years (SD 6.95)) with preoperative spinopelvic mobility, radiological analysis, and postoperative CT scans were retrospectively reviewed. Acetabular component anteversion was measured on postoperative CTL radiographs and CT scans using 3D reconstructions of the pelvis. Two cohorts were identified based on a CTL-CT error of ≥ 10° (n = 11) or < 10° (n = 36). Spinopelvic mobility parameters were compared using independent-samples t-tests. Correlation between error and mobility parameters were assessed with Pearson's coefficient. Patients with CTL error > 10° (10° to 14°) had stiffer lumbar spines with less mean lumbar flexion (38.9°(SD 11.6°) vs 47.4° (SD 13.1°); p = 0.030), different sagittal balance measured by pelvic incidence-lumbar lordosis mismatch (5.9° (SD 18.8°) vs -1.7° (SD 9.8°); p = 0.042), more pelvic extension when seated (pelvic tilt -9.7° (SD 14.1°) vs -2.2° (SD 13.2°); p = 0.050), and greater change in pelvic tilt between supine and seated positions (12.6° (SD 12.1°) vs 4.7° (SD 12.5°); p = 0.036). The CTL measurement error showed a positive correlation with increased CTL anteversion (r = 0.5; p = 0.001), standing lordosis (r = 0.23; p = 0.050), seated lordosis (r = 0.4; p = 0.009), and pelvic tilt change between supine and step-up positions (r = 0.34; p = 0.010). Differences in spinopelvic mobility may explain the variability of acetabular anteversion measurements made on CTL radiographs. Patients with stiff spines and increased compensatory pelvic movement have less accurate measurements on CTL radiographs. Flexion of the contralateral hip is required to obtain clear CTL radiographs. In patients with lumbar stiffness, this movement may extend the pelvis and increase anteversion of the acetabulum on CTL views. Reliable analysis of acetabular component anteversion in this patient population may require advanced imaging with a CT scan. Cite this article: Bone Joint J2021;103-B(7 Supple B):59-65.

Hip arthroscopy has good clinical outcomes in the treatment of osteoid osteoma of the acetabulum

BackgroundOsteoid osteoma (OO) of the acetabulum is a relatively rare disease. However, the the clinical outcomes of hip arthroscopy for treatment of OO of the acetabulum are still uncertain.MethodsWe evaluated consecutive patients who were diagnosed with OO of the acetabulum and who underwent hip arthroscopy at our hospital between January 2013 and March 2020. All patients underwent a preoperative physical examination. Preoperative supine anteroposterior hip radiography, cross-table lateral radiographs, computed tomography (CT), and magnetic resonance imaging were performed in all patients. The alpha angle and lateral center-edge angle were measured before surgery. Supine anteroposterior hip radiography and CT were performed in all patients postoperatively. Preoperative patient-reported outcomes (PROs), including Visual Analog Scale (VAS), the International Hip Outcome Tool-12 (iHOT-12) and modified Harris Hip Score (mHHS), and PROs at final follow-up were evaluated.ResultsA total of 6 patients (mean age, 18.7 years; age range, 6–31 years; 5 males and 1 females) were included in this study. The average follow-up period after surgery was 28.3 months (range, 6–90 months). Before surgery, the mean mHHS was 45.2 ± 10.5 (range, 33–56), the mean iHOT-12 was 33.3 ± 14.5 (range, 13–49), and mean VAS was 8.2 ± 1.0 (range, 7–9). At one month after surgery, mean mHHS was 78.7 ± 1.9 (range, 77–81), iHOT-12 was 71.0 ± 4.5 (range, 68–80), and mean VAS was 0. At the final post-operative follow-up, mean mHHS was 89.2 ± 2.1 (range, 86–91), iHOT-12 was 93.5 ± 5.0 (range, 88–98), and mean VAS was 0. All results, except VAS between one month after surgery and at final follow-up, demonstrated statistically significant improvement (P < 0.05). One patient underwent revision surgery.ConclusionsHip arthroscopy has good clinical outcomes in the treatment of OO of the acetabulum. Further study on the mechanism of secondary femoroacetabular impingement (FAI) caused by OO of the acetabulum is needed. More cases of arthroscopic excision and longer follow-up are also needed to better prove the clinical outcomes of hip arthroscopy for OO of the acetabulum.

A Deep Learning Tool for Automated Radiographic Measurement of Acetabular Component Inclination and Version After Total Hip Arthroplasty

BackgroundInappropriate acetabular component angular position is believed to increase the risk of hip dislocation after total hip arthroplasty. However, manual measurement of these angles is time consuming and prone to interobserver variability. The purpose of this study was to develop a deep learning tool to automate the measurement of acetabular component angles on postoperative radiographs. MethodsTwo cohorts of 600 anteroposterior (AP) pelvis and 600 cross-table lateral hip postoperative radiographs were used to develop deep learning models to segment the acetabular component and the ischial tuberosities. Cohorts were manually annotated, augmented, and randomly split to train-validation-test data sets on an 8:1:1 basis. Two U-Net convolutional neural network models (one for AP and one for cross-table lateral radiographs) were trained for 50 epochs. Image processing was then deployed to measure the acetabular component angles on the predicted masks for anatomical landmarks. Performance of the tool was tested on 80 AP and 80 cross-table lateral radiographs. ResultsThe convolutional neural network models achieved a mean Dice similarity coefficient of 0.878 and 0.903 on AP and cross-table lateral test data sets, respectively. The mean difference between human-level and machine-level measurements was 1.35° (σ = 1.07°) and 1.39° (σ = 1.27°) for the inclination and anteversion angles, respectively. Differences of 5⁰ or more between human-level and machine-level measurements were observed in less than 2.5% of cases. ConclusionWe developed a highly accurate deep learning tool to automate the measurement of angular position of acetabular components for use in both clinical and research settings. Level of EvidenceIII.

Birmingham hip resurfacing: Short term results

Aim: Hip joint replacement provides a dramatic improvement in the quality of life of patients with hip arthrosis but this effect has not been fully achieved in young patients because of early failure with total hip arthroplasty with high activity level. A bone mass protective procedure such as hip resurfacing arthroplasty might be advantageous in young patients. Many options for hip resurfacing prosthesis are available. One of the most used is the Birmingham hip resurfacing prosthesis. The purpose of this investigation compared retrospectively the functional, clinical and radiological outcomes of patients who underwent Birmingham hip resurfacing arthroplasty by a single surgeon for various hip arthrosis.Materials and Methods: Twenty-six hips of 22 patients (12 male, 10 female) were evaluated by using Harris hip score preoperatively and postoperatively. Anteroposterior, lateral and cross-table lateral radiographs of the pelvis and hips were evaluated with respect to component position, migration, and radiolucency postoperatively and at every follow up. Acetabular inclination and anteversion angle, implant-femoral shaft angle, varus and valgus positon, pseudotumor formation around the hip were evaluated by radiologist. Blood samples of patients were taken at last follow ups and evaluated for cobalt and chromium levels by using an inductively-coupled plasma mass spectrometer. Results: Postoperative Harris hip scorewas found to be significantly higher than preoperative Harris hip score. Correlation between chromium ion and size of femoral component, cobalt ion and cup anteversion angle had inverse relationship. There was significant correlation between cobalt ion and gender; females had higher levels of cobalt ion than males.Conclusion: In order to avoid ion load in Birmingham hip resurfacing, caution in selection of patients, avoidance of the use of small components, and attention to the surgical technique to ensure proper placement of the component angles are crucial.

3D simulation of radiographic projections to test and reduce the effect of pelvic tilt on the accuracy of cross-table lateral radiography

BackgroundCross-table lateral (CL) radiography is a convenient and feasible method to assess cup version angle (VA) after total hip arthroplasty; However, pelvic tilt (PT) may contribute to its measurement inaccuracy. How PT affects CL radiographic measurements have not been well studied. We sought (1) to determine the effect of the PT on cup version measurement on CL radiography and (2) to develop a method for reducing measurement errors caused by the PT.MethodsWe used 3D technique to construct standard model and capture CL radiography simulation. A linear regression model was created to analyze the relationship between PT and VA. CL radiography and computed tomography (CT) were performed for the enrolled patients after surgery. The consistency between CL and CT measurements were verified by intra-class correlation coefficient (ICC).ResultsThere was a high correlation between the VA and PT. For each 1-degree increased in the PT, the VA decreased by 0.76° (R2 = 0.995, p < 0.001). Based on the data, we created a corrective formula to convert the radiographic measurements into values approximating the actual VA under a natural pelvic position. The VA measurements corrected by our equation was in high agreement with the CT-measured values with reference to the corresponding PT (ICC = 0.988, p < 0.001), which was in sharp contrast to that without PT control (ICC = 0.454, p = 0.203).ConclusionsThe PT may contribute to cup version measurement inaccuracies on CL radiography. Our mathematical algorithm can serve as a reliable method to improve the accuracy of CL radiography.

Modular Dual-Mobility Liner Malseating: A Radiographic Analysis.

BackgroundWith dislocation as a leading cause for revision after total hip arthroplasty (THA), modular dual-mobility (MDM) constructs are more commonly used at present in an attempt to decrease postoperative instability. With modularity, there is potential for additional complications, including malseating of the liner. The goal of this study was to perform a radiographic analysis on the incidence of MDM liner malseating.MethodsWe retrospectively identified 305 patients (305 THAs) who underwent primary THA with an MDM liner from a single manufacturer inserted by a single surgeon. One hundred fifty-six (51%) patients were male. The mean age was 68 years, and the mean body mass index was 31 kg/m2. Only patients with both anteroposterior and cross-table lateral radiographs at a minimum of 6 weeks postoperatively were included. Dislocations and reoperations were determined at 1 year after the procedure. All MDM liners were routinely tested intraoperatively with a "4-quadrant test" to assess for proper seating.ResultsFour (4/305, 1.3%) MDM liners were noted to be radiographically malseated at early follow-up with three (3/147, 2.0%) occurring in a thinner two dimentional (2D) ongrowth shell and only one (1/158, 0.6%) observed in a thicker three dimentional (3D) additively manufactured shell. They were inferiorly prominent by a median of 1.2 mm, best seen on the cross-table lateral radiograph. In patients with at least 1-year follow-up, no MDM liners dissociated and no patients sustained a dislocation. Five (1.6%) patients required reoperation unrelated to the acetabular or MDM construct.ConclusionsSurgeons should be aware that malseating of dual-mobility liners may occur. However, with utilization of a consistent surgical technique to test for seating of the liner, the radiographic incidence of MDM liner malseating was low at 1%. Although there were no short-term clinical implications of liner malseating, long-term follow-up is needed.

Evaluation of version of acetabular component following total hip replacement on conventional radiograph and computed tomography

Background/Purpose: Total hip replacement (THR) is considered as one of the most successful orthopedic procedures. However, improperly placed components can lead to instability and accelerated wear. Acetabular cup inclination can be very well accessed by anteroposterior pelvis X-rays; for acetabular version assessment, computed tomography (CT) scan is the gold standard. CT scan is not readily available at many centers and the surgeon has to rely on X-ray methods for evaluation of acetabular version to audit results and to predict behavior of the surgical intervention. This prospective study was undertaken to compare Woo and Morrey’s and ischiolateral methods of assessment of acetabular version on cross-table lateral radiographs with CT assessment and to assess the validity of radiographic methods with respect to CT scan method. Material and methods: A prospective follow-up study was conducted for 18 months’ duration (October 2016 to March 2018) on 30 adult patients who underwent THR surgery. Cross-table lateral radiograph was obtained at 3 and 6 weeks in the postoperative period. Two observers made each observation at two different points of time. CT scan was performed at 3 weeks. Version as measured by radiographs and CT scan was recorded. Results: The major overlap in the distribution of the values of the Woo and Morrey method suggests that there is no significant difference between the observations. Distribution of the values of the ischiolateral view and the CT scan value distributions have a very small overlap and hence suggest a strong significant difference between the two. Conclusion: In this study, Woo and Morrey’s method and ischiolateral method of assessment of acetabular version were compared with CT assessment. We found that in Woo and Morrey’s method, values were comparable to CT scan values, when put on regression line. However, in situation of change in patient positioning, namely hip stiffness in contralateral hip, measurement of component changed in series of radiography due to differences in pelvis tilt. So, in these circumstances, we can use ischiolateral method which can give consistent measurement. But it will not be in concordance with CT scan values and Woo and Morrey values, as represented in regression line. The high intra-class correlation coefficients for both intra- and inter-observer reliability indicated that the angle measured with these methods is consistent and reproducible for multiple observers. CT, however, be considered as gold standard for measurement owing to control over pelvic rotation and/or tilt/patient positioning.

Differentiating Nutrient Artery Canals of the Femur versus Fracture Lines in Patients with Total Hip Arthroplasty on Plain Radiographs.

Background:Nutrient artery canals of the femur are often visible on plain radiographs as radiolucent lines which may mimic fracture lines. The purpose of this study was to distinguish nutrient artery canals from fracture lines on plain radiographs.Materials and Methods:Ninety-three patients (102 hips) with an average age of 65.6 years were included in the study. We retrospectively analyzed nutrient artery canals of the femur on pre and postoperative anteroposterior (AP) and cross-table lateral (CTL) hip radiographs in patients with cementless total hip arthroplasty. The shape, number, location, direction of obliquity, length of nutrient artery canal, and the distance between the tip of the greater trochanter and the proximal end of the nutrient artery canal were measured.Results:Nutrient artery canals were determined in 54 hips (53.0%) on preoperative radiographs. The numbers of nutrient artery canals were entirely found to be one for each hip. The nutrient artery canals of the femur were the most frequently seen in the cortex on CTL radiographs with 32 hips (31.4%), whereas nutrient artery canals were not seen at all in the cortex on AP radiographs. All nutrient artery canals in the cortex on CTL radiographs coursed upward obliquely. Comparing to fracture lines, nutrient artery canals show less radiolucency, smaller diameter, and blunted ends in both the cortex and medullary cavity, show sclerotic walls in the cortex and have the less straight course in the medullary cavity.Conclusions:Based on the results of this study, there are clearly distinguishable differences between nutrient artery canals of the femur and fracture lines on plain radiographs.

Relative Contribution of Acetabular and Femoral Reconstruction to Prosthetic Joint Instability Risk after Primary Total Hip Arthroplasty

AbstractProsthetic joint instability is a challenging concern for a minority of total hip arthroplasty (THA) patients. Placement of the acetabular component within the traditional safe zone does not eliminate dislocation, and the relative contribution of femoral length and offset to instability risk has not been well defined. The authors compared 53 dislocated primary THAs treated against an age- and gender-matched cohort of 134 stable primary THAs. Anteroposterior and cross-table lateral radiographs were used to determine whether reconstructions met targets for acetabular inclination (30–50 degrees), acetabular anteversion (5–30 degrees), femoral length (0–9.9 mm) and femoral offset (0–9.9 mm). Statistical analysis was performed to assess univariate and multivariate relationships with an instability event; statistical significance was set using a two-sided p-value &lt; 0.05. Forty-seven (88.7%) of the dislocating hips had nonoptimal acetabular or femoral reconstructions. While a similar proportion of patients in the study and control groups had acetabular reconstruction within the safe zone (51.5 vs. 47.2%, p = 0.63) patients with unstable hips were more likely to have acetabular component inclination outside of the target zone (30.2 vs. 7.5%, p &lt; 0.01), acetabular anteversion &lt; 15 degrees (30.2 vs. 3.7%, p &lt; 0.0001), reduced femoral length (35.9 vs. 3.7%, p &lt; 0.0001), and reduced femoral offset (41.5 vs. 7.46%, p &lt; 0.0001). Stepwise multivariate logistic regression was performed and identified femoral head size less than 32 mm (OR 2.9, 95% CI 1.4–6.2) and higher inclination angle (OR 1.1, 95% CI 1.04–1.2) as significant independent risk factors for hip instability. The authors' study findings suggest that insufficient acetabular anteversion, femoral length, and femoral offset reconstruction contribute significantly to instability risk following THA. Using a larger femoral head is protective, but should be balanced against long-term volumetric wear risk.