Aims. Assessment of bone mineral density (BMD) with dual-energy X-ray absorptiometry (DXA) is a well-established clinical technique, but it is not available in the acute trauma setting. Thus, it cannot provide a preoperative estimation of BMD to help guide the technique of fracture fixation. Alternative methods that have been suggested for assessing BMD include: 1) cortical measures, such as cortical ratios and combined cortical scores; and 2) aluminium grading systems from preoperative digital radiographs. However, limited research has been performed in this area to validate the different methods. The aim of this study was to investigate the evaluation of BMD from digital radiographs by comparing various methods against DXA scanning. Methods. A total of 54 patients with distal radial fractures were included in the study. Each underwent posteroanterior (PA) and lateral radiographs of the injured wrist with an aluminium step wedge. Overall 27 patients underwent routine DXA scanning of the hip and lumbar spine, with 13 undergoing additional DXA scanning of the uninjured forearm. Analysis of radiographs was performed on ImageJ and Matlab with calculations of cortical measures, cortical indices, combined cortical scores, and aluminium equivalent grading. Results. Cortical measures showed varying correlations with the forearm DXA results (range: Pearson correlation coefficient (r) = 0.343 (p = 0.251) to r = 0.521 (p = 0.068)), with none showing statistically significant correlations. Aluminium equivalent grading showed statistically significant correlations with the forearm DXA of the corresponding region of interest (p < 0.017). Conclusion. Cortical measures, cortical indices, and combined cortical scores did not show a statistically significant correlation to forearm DXA measures. Aluminium-equivalent is an easily applicable method for estimation of BMD from digital radiographs in the preoperative setting. Cite this article: Bone Joint Res 2021;10(12):830–839

In 20 patients undergoing hybrid total hip arthroplasty, the reproducibility and accuracy of templating using digital radiographs were assessed. Digital images were manipulated using either a ten-pence coin as a marker to scale for magnification, or two digital-line methods using computer software. On-screen images were templated with standard acetate templates and compared with templating performed on hard-copy digital prints. The digital-line methods were the least reliable and accuracy of sizing compared with the inserted prostheses varied between −1.6% and +10.2%. The hard-copy radiographs showed better reproducibility than the ten-pence coin method, but were less accurate with 3.7% undersizing. The ten-pence coin method was the most accurate, with no significant differences for offset or acetabulum, and undersizing of only 0.9%. On-screen templating of digital radiographs with standard acetate templates is accurate and reproducible if a radiopaque marker such as a ten-pence coin is included when the original radiograph is taken

Magnification of anteroposterior radiographs of the pelvis is variable. To improve the accuracy of templating, reliable and radiographer-friendly methods of scaling are necessary. We assessed two methods of scaling digital radiographs of the pelvis: placing a coin of known diameter in the plane of interest between the patient’s thighs, and using a caliper to measure the bony width of the pelvis. A total of 39 patients who had recently undergone hemiarthroplasty of the hip or total hip replacement were enrolled in the study. The accuracy of the methods was assessed by comparing the actual diameter of the head of the prosthesis with the measured on-screen value. The coin method was within a mean of 1.12% (0% to 2.38%) of the actual measurement, the caliper group within 6.99% (0% to 16.67%). The coin method was significantly more accurate (p < 0.001). It was also reliable and radiographer friendly. We recommend it as the method of choice for scaling radiographs of the pelvis before hip surgery

Introduction: Preoperative planning is an important issue for total hip arthroplasty (THA). We normally use a traditional handwritten method with X-ray and two-dimensional (2-D) template. This method is simple and easy to plan the THA. However the 2-D planning is not accurately analyzed for especially DDH or severe deformity. New three-dimensional (3-D) preoperative planning software (ATHENA, Soft Cube) was developed for total knee replacement. The method of this software is based on roentogen stereophotogrammetoric analysis (RSA). The software can superimpose the 3-D CT and the prosthetic CAD model onto 2 X-rays. We hypothesized that this software would improve the accuracy of preoperative THA planning compared to the 2-D planning. Materials and Methods: Fifty patients (male/female = 2/48) underwent THA using cementless stem and cementless acetabular component. Preoperatively, two different planning Methods: were done for all hips. The conventional 2-D handwritten planning was done with a template of the total hip system based on a standard AP X-ray of the hip (Group 1). Each patient had 2 directions X-ray with a particular marker and CT around only hip. The software calculated the source position of X-ray in each view by the marker and the angle between 2 X-rays based on RSA. The software superimposed the 3-D CT hip model and the proper size prosthetic CAD model onto 2 X-rays (Group 2). Results: The acetabular component implanted was the same as that planned in 78% (Group 1) and 90% (Group2). The stem implanted was the same as that planned in 38% (Group 1) and 68% (Group2). The stem planning with the software improved significantly compared to the 2-D templating (P< 0.05, Chi-square for independence test). Discussion and Conclusions: CT based computer preoperative planning was introduced to improve the accuracy of THA planning and reported good results in recent years. However the CT based method depends on high quality CT and cannot use effectively X-ray. This 3-D preoperative planning software can synchronize both digital X-ray and CT and define proper 3-D space. The software corrects the CAD model’s angles such as ante-version and torsional abnormalities accurately and easily in the same space. We can confirm those data simultaneously and get a lot of accurate information before the surgery. This method improves the accuracy of THA

The Adora RSA (NRT, Denmark) is a new stereo X-ray system custom built for Radeostereometry. Images are acquired using CXDI50C digital detectors (Canon, Netherlands). Analysis software was written locally to detect both Tantalum markers and the spherical head of the hip implant, and for RSA reconstruction and kinematic analysis.

To assess geometric reproducibility, a planar grid phantom was constructed with 1400 2mm markers in a grid pattern over a 350 by 430 mm glass plate. Additionally 25 tantalum markers of each diameter 1.0, 0.8 and 0.5 mm were added within a 120mm square of the grid. The phantom was imaged repeatedly with translation and rotation over the detector. For small phantom movements of up to 10mm over the detector, very small measurement errors were observed of median 2 microns, maximum 6 microns. For larger movements, the errors increased to median 5 microns and maximum 50 microns. Errors also increased with decreasing exposure.

For RSA validation, an acetabular PE cup was cemented to a Sawbone pelvis. Tantalum markers were inserted into the pelvis (10), cement (4), and cup (10). A 28mm metal head was fixed to the cup. The phantom was imaged repeatedly without movement, then moved in translation (up to 100 mm) and rotation (all axes, up to 45 degrees), and with full X-ray repositioning. Precision errors were calculated on the assumption of no relative movement between components.

Results are given for repositioning movement categorised as none, small (less than 25mm or 15 degrees), medium (less than 50mm or 30 degrees), and large. For the head, the mean total point motion error was 4, 10, 14 and 24 micrometers. Mean error of segment fitting was less than 60 microns with no markers rejected from the composite segment of 24 markers. Cup migration total translation error was 10, 16, 24, and 35 micrometers with rotation errors less than 0.05 degrees.

Observed RSA errors were small, increasing with phantom movement. This is consistent with the geometric uniformity tests. X-ray exposure and tissue thickness were also identified as factors in precision. We conclude this system has excellent precision for Radiostereometry.

Aims

In this randomized study, we aimed to compare quality of regenerate in monolateral versus circular frame fixation in 30 patients with infected nonunion of tibia.

Introduction: Several factors render plain X-ray radiographs of the hip unsuitable for bone mineral density measurements, mainly variability in X-ray exposure levels and soft tissue surrounding the bone. We present modification of proximal femur digital radiographs to compensate for these interfering factors. Methods: The study population consisted of 99 women, in three groups: 1 – elderly, sustaining a fracture of the neck of the femur. 2 – elderly, without a fracture. 3 – young. Each patient’s hip was radiographed with a brass step-wedge for standard reference. Dual-Energy X-ray Absorptiometry (DEXA) of the same hip was performed. On each radiograph, Regions Of Interest (ROIs) of the proximal femur were determined in concordance with ROI of the DEXA, together with three soft tissue regions surrounding the bone. Mean gray level was measured for each ROI. Results: The difference in gray level of the ROI within the proximal femur was not statistically significant between the groups. Correction of bone gray level to exposure level by dividing the gray level of the ROI to that of the step wedge, resulted in statistically significant difference between group 1 and either group 2 or group 3. Similar results were obtained by correction of bone gray level to soft tissue gray level. Using this method, multiple R. 2. of 0.62 was found predicting the DEXA value from the gray level of each ROI. Conclusions: After correction to the exposure level and to the soft tissue surrounding the bone, a plain digital radiograph of the pelvis can provide valuable information concerning the bone mineral content of the proximal femur. These preliminary results warrant further research aimed at exploring the potential value of this fast, accessible and relatively inexpensive technique to diagnose osteoporosis and the prediction of future fractures

Aims. The aim of this study was to create artificial intelligence (AI) software with the purpose of providing a second opinion to physicians to support distal radius fracture (DRF) detection, and to compare the accuracy of fracture detection of physicians with and without software support. Methods. The dataset consisted of 26,121 anonymized anterior-posterior (AP) and lateral standard view radiographs of the wrist, with and without DRF. The convolutional neural network (CNN) model was trained to detect the presence of a DRF by comparing the radiographs containing a fracture to the inconspicuous ones. A total of 11 physicians (six surgeons in training and five hand surgeons) assessed 200 pairs of randomly selected digital radiographs of the wrist (AP and lateral) for the presence of a DRF. The same images were first evaluated without, and then with, the support of the CNN model, and the diagnostic accuracy of the two methods was compared. Results. At the time of the study, the CNN model showed an area under the receiver operating curve of 0.97. AI assistance improved the physician’s sensitivity (correct fracture detection) from 80% to 87%, and the specificity (correct fracture exclusion) from 91% to 95%. The overall error rate (combined false positive and false negative) was reduced from 14% without AI to 9% with AI. Conclusion. The use of a CNN model as a second opinion can improve the diagnostic accuracy of DRF detection in the study setting. Cite this article: Bone Joint Res 2024;13(10):588–595

Aims. The aims of this study were to identify means to quantify coronal plane displacement associated with distal radius fractures (DRFs), and to understand their relationship to radial inclination (RI). Methods. From posteroanterior digital radiographs of healed DRFs in 398 female patients aged 70 years or older, and 32 unfractured control wrists, the relationships of RI, quantifiably, to four linear measurements made perpendicular to reference distal radial shaft (DRS) and ulnar shaft (DUS) axes were analyzed: 1) DRS to radial aspect of ulnar head (DRS-U); 2) DUS to volar-ulnar corner of distal radius (DUS-R); 3) DRS to proximal capitate (DRS-PC); and 4) DRS to DUS (interaxis distance, IAD); and, qualitatively, to the distal ulnar fracture, and its intersection with the DUS axis. Results. In the study (fracture) and control groups, respectively, the mean values were: RI, 17.2° (SD 7.2°; -7° to 35°) and 25.6° (SD 2.6°; 21° to 30°); DRS-U, 13.5 mm (SD 1.7; 4.9 to 20.8) and 15.3 mm (SD 0.72; 13.8 to 16.3); DUS-R, 13.4 mm (SD 2.1; 4.8 to 18.5) and 12.0 mm (SD 0.99; 9.7 to 13.9); DRS-PC (positive value radial to DRS, negative value ulnar), 0.14 mm (SD 5.4; -10.9 to 22.7) and -6.1 mm (SD 1.6; -10.6 to -2.3); and IAD, 25.3 mm (SD 2.5; 17.6 to 31.1) and 27.1 mm (SD 1.5; 24.5 to 31.0). All means were significantly different between the study and control groups. RI correlated strongly with DRS-PC. Ulnar styloid fracture intersection with the DUS axis, reflective of ulnar translation of both radial and ulnar shafts, was associated with significantly lower RI. Conclusion. After DRF, the relationship of the proximal capitate to the DRS axis in the coronal plane correlates with the final radial inclination. Additionally, ulnar styloid intersection with the DUS axis is associated with even lower radial inclination. DRF reduction should seek to restore the normal coronal relationship of both radial and ulnar shafts to their distal counterparts. Cite this article: Bone Joint J 2023;105-B(6):688–695

Aim: to compare the reliability of pre-operative templating for total hip and knee arthroplasty using printed digital radiographs versus conventional radiographs. Materials and Methods: a prospective continuous study commenced January 2005. The PACS digital imaging system was introduced in May 2005 and the radiology department adopted a policy of printing orthopaedic radiographs to ‘true size’. All consultants and their registrars undertaking primary total hip and knee arthroplasty were asked to participate in the study and agreed. The operating surgeon completed a proforma for each Total Hip Replacement (THR) performed noting the templated cup and stem size and offset. Following the surgery the actual sizes and offset of the components implanted were also recorded on the proforma. A similar procedure was followed for the femoral and tibial components of Total Knee Replacements (TKR). Results: there were 254 completed proformae. 186 pro-formae for conventional radiographs and 68 proformae for printed digital radiographs. Templating was possible from all the conventional radiographs; however templating was only possible from 58 of 68 (85%) digital radiographs as the images were obviously not true size. The templated sizes of both hip and knee components from conventional radiographs were more predictive of the actual size implanted in all cases. Furthermore there were a greater number of predicted outlying sizes using printed digital radiographs. Conclusion: digital radiographs, even those said to be true size are unreliable for the purposes of pre-operative planning

Motorcycle accident-related traffic accidents contribute significantly to the burden of orthopaedic injuries seen in the South African Healthcare system. Subsequent to the Covid-19 pandemic, there has been an increase in the number of delivery drivers on the roads of South Africa. Many of these delivery drivers have no formal employment contracts. We aim to describe the demographics and injury patterns in motorcyclists involved in time dependent delivery work in South Africa; and to quantify the cost to the state of their orthopaedic surgeries. We performed a consecutive case series study at all of the hospitals draining the study region over the period of one year. Epidemiological, clinical and cost to hospital data was collected from medical records, digital radiographs, theatre invoices and a dedicated patient questionnaire. Provisional. So far 41 delivery drivers were captured by the study over a period of 11 months. All drivers were male and the vast majority foreign nationals. 11 patients were polytraumatised and 5 required admission to an intensive care unit. The most common injury patterns were closed femur fractures (17) followed by tibial shaft fractures (13). The average cost of surgery was R35 049 and average cost of ward stay R44 882 at an average of 10 days admission in a general ward. Overall, an estimated total of R 3.1 million rand was spent on these injuries. Informally employed “app users” performing delivery work on motorcycles in South Africa have added a significant burden to the cost of state healthcare since 2020. The vast majority of these patients are foreign nationals who do not hold South African licences or health insurance. They are sustaining high energy injuries typical of motorcycle-car accidents and many of them are left with lifelong loss of function

The aim of the study was to evaluate radiological and clinical outcomes of surgical treatment of developmental dysplasia of the hip (DDH) with Periacetabular Osteotomy (PAO) and to determine the values of radiological parameters allowing us to obtain an optimal clinical result. Radiological evaluation included a standardized AP digital radiograph of the hip joints. Centre edge angle (CEA), medialization, distalization, femoral head coverage (FHC) and ilioischial angle were measured. Clinical evaluation based on HHS, WOMAC, Merle d'Aubigne-Postel scales and Hip Lag Sign. Radiological and clinical evaluation was performed preoperatively and approximately 12 months after the surgery. Statistically significant (p<0.05) differences in radiological measurements and all clinical scales have been observed pre- and postoperatively for all of the parameters. The results of PAO presented decreased medialization by 3.4mm (range: 3 to 3.7), distalization by 3.5mm (range: 3.2 to 3.8) and the ilioischial angle by 2.7° (range: 2.2 to 3.7). There was also an improvement in the femoral head bone coverage: CEA increased by 16.3° (range: 12.1˚ to 20.5˚) and FHC by 15.2% (range: 10.8 to 19.8). Clinically we observed an increase in HHS by 22 points (range: 15.8 to 28.2) and M. Postel d'Aubigne by 3.5 points (range: 2.0 to 4.4) and a decrease in WOMAC by 24% (range: 22.6 to 25.8). HLS improvement of gluteal muscles’ efficiency has been observed in 67% of patients postoperatively. This study revealed that the qualification of patients with DDH for an elective PAO is more justified due to the predicted optimal clinical outcomes based on three parameters: CEA <25 degrees, FHC <75%, and ilioischial angle >85.9 degrees. Accordingly, to achieve better clinical results for all scales, it is necessary to increase the average CEA value by 11˚, the average FHC by 11%, and reduce the average ilioischial angle by 3˚

Objective. Several researchers have reported that imageless navigation is a reliable technique and results in more precise cup placement compared to conventional freehand techniques, however, few studies have been reported about the accuracy of the femoral stem placement. The primary aim of this study was to evaluate the precision of an imageless navigation system in measuring the limb length change. The secondary aim was to evaluate LLD following imageless navigation THA with modified registration technique in semilateral decubitus position. Methods. The authors reviewed 66 cases receiving cementless THA with imageless navigation from September 2013 to December 2014. The radiographic limb length change measured from pre-operative and post-operative digital x-ray was compared with the intraoperative calculation by the navigation system. Postoperative LLD in unilateral cases and second operation of staged bilateral cases were also recorded. Results. The mean radiographic limb length change measured on digital x-ray was 17.4 mm (5 to 29.3, SD 5.7). The mean limb length change calculated by navigation system was 16.8 mm (3 to 28, SD 5.9). The mean paired difference was 2.27 mm (−6 to 8, SD 0.9). This difference was significant (p=0.01). There was significant correlation between LL change measured on digital x-ray and which were calculated by navigation system (r=0.95, p<0.001). The navigation system had an accuracy of within 1 mm of the radiographic measurement in 7.6% of cases, within 2 mm in 39.4% of cases and within 5 mm in 93.9% of cases. The mean postoperative LLD was 2 mm (0 to 7, SD 1.9), 92% were within 5 mm. Conclusion. This study showed that the imageless navigation THA with modified registration technique in semilateral decubitus position offered a precise limb length measurement and the results were very encouraging for clinical use to minimize LLD in THA

Aim To determine the variability of magnification with digital radiographs and thereby improve the accuracy of templating. Materials and methods We have previously described a method of taping a ten pence coin in the region of the greater trochanter, on the basis that it is cheap, easily available and of constant diameter and radio-opacity. The magnification may then be deduced by dividing the coin’s maximal projected diameter by its actual diameter of 24.5 millimetres, as per the Royal Mint’s specifications. The perceived maximal diameter of the coin’s projected image was measured, to the nearest 0.5mm on each illuminated hard film using a standard 30 centimetre ruler with millimetres scale. Coin diameters were subsequently measured to the nearest hundredth millimetres on the digital radiographs. Results 20 AP digital pelvic radiographs (hard copies and digital images) were analysed. The ranges were as follows: 27.17 to 29.40 mms actual, equating to magnification range 10.9 to 20.00 per cent. Conclusions This study has demonstrated that magnification on digital radiographs is not as constant as previously assumed. Prior to this study a magnification factor of 10% was assumed to be standard on all pelvic X-rays and was the basis of templating. We now recommend using a set magnification of 15% in our department, or to be more accurate using radio-opaque markers for templating

This study determined the inter-reader and intra-reader reliability of lower limb frontal plane alignment measures obtained from digital radiographs using a computer software program. Measurements of lower limb frontal plane alignment were obtained from over 3000 full limb digital radiographs of both limbs of persons ‘at risk’ for developing knee osteoarthritis (OA), as part of the Multicenter Osteoarthritis Study (MOST). Three trained clinicians used a computer software program (Horizon Image Viewer, version 1.5, OAISYS Medical Inc.) to locate bone landmarks on the femur and tibia from which standard measures of alignment (e.g. the Hip-Knee-Ankle (HKA) angle) and bone lengths could be computed. To assess the reliability of these alignment measurements, one hundred randomly assigned digital radiographs, representing two hundred limbs, were selected from the complete data set for a repeated analysis carried out two or more weeks after completion of the first measurements. Random effects two-way analysis of variance (ANOVA) models were applied to estimate the interclass and intraclass correlation coefficients (ICC), which correspondingly evaluated inter-reader and intra-reader reliability for each of the angles and bone lengths. High reliability measures were obtained for the HKA angle (inter-reader reliability: ICC=0.995 (95% CI, 0.994–1); intra-reader reliability: ICC= 0.998 (95% CI, 0.998–1)). Reliability for additional angles between the femur and tibia ranged from 0.839 to 0.993 (inter-reader reliability) and 0.908 to 0.998 (intra-reader reliability). High reliability measures were also obtained for bone lengths (inter-reader reliability: ICC from 0.993 to 0.995; intra-reader reliability: ICC from 0.994 to 0.995). Each of the lower limb alignment and bone length measurements were highly reliable. The outcome supports the use of computer software programs and software tools for analysis of lower limb frontal plane alignment

To determine the range of in-vivo magnification error in lateral spinal digital radiographs, and determine the effect of BMI on this error. An analysis of two hundred and fifty patients with digital radiographs and CT/MRIs was performed. Digital imaging software was used to measure the antero-posterior vertebral body dimensions (VBD) at C2, C5, L1, and L4. Magnification values were determined in comparison to CT/MRI. CT measurements were also compared to MRI. BMI for each patient was obtained by chart review. The difference between the mean VBD as measured on CT and MRI was < 0.1mm (n=130, p< 0.2514, paired t-test). Mean magnification at the cervical spine was 21% (1.21 ± 0.01; range = 1.06–1.57 (n=177)) and 31% at the lumbar spine (1.31 ± 0.01; range = 1.09–1.63 (n=284)). Linear regression showed a significant positive correlation between BMI and magnification at both the cervical and lumbar spine (Cervical: n=96; p=0.0019; Lumbar: n=144; p< 0.0001). There was a significant difference in magnification between non-obese and obese patients at both the cervical and lumbar levels. Cervical: 1.19 ± 0.01 magnification for non-obese (n=136), versus 1.26 ± 0.01 for obese (n=39) (p< 0.0001). Lumbar: 1.28 ± 0.01 (n=207), versus 1.38 ± 0.01 (n=71) (p< 0.0001), respectively. Linear in-vivo measurements obtained on digital radiographs are subject to magnification errors at both cervical and lumbar spine. This error correlates to the patient’s BMI. Consequently, clinical-decision making, regardless of the anatomical area, that is based on linear measurements obtained from radiographs that do not account for this error are invalid. In the scenario that this measurement is crucial (e.g. dynamic radiographs), this error can be corrected by comparison to morphometric data from CT/MRI

Digital templating was used in 50 patients who underwent THA using Merge Ortho software, Cedara. Clinical examination was performed first, to measure leg lengths and account for pelvic obliquity and flexion deformity. Good quality digital radiographs were obtained with anteroposterior and lateral views extending beyond the tip of the femoral component and the cement restrictor. A coin was placed on the ASIS to help in determining radiological magnification. Digital radiographs were saved in DICOM format and imported to EndoMap software system. A 6-step technique was used for templating as follows:. Radiographic assessment; looking at the quality of bone, amount of bone stock, dysplasia, osteophytes, and other abnormalities. Correction of magnification; following the specific instructions of the software, by measuring the diameter of the coin on the digital radiograph. 3. Measuring leg length discrepancy; the software system automatically calculated the leg length discrepancy, even in the presence of pelvic obliquity (Figure1). 4. Templating acetabular component; the desired cup was selected from the implant library after identifying important landmarks. The size and position was modified to fit the acetabulum and to restore the center of rotation of the hip, considering minimal bone removal and sufficient bone coverage laterally. Templating femoral component; the size and position of the desired stem was adjusted to fit the femoral canal, different offsets were compared to find the best match for the patient's original offset. Correction of leg length discrepancy and measuring length of neck resection; the height of the femoral stem was adjusted to correct any leg length discrepancy by placing the center of the head above the center of the cup by the same length of discrepancy. Then the level of the neck resection was marked at the level of the stem collar and the femoral neck cut was measured by a digital ruler from the tip of the lesser trochanter to the mark of neck resection. In case of leg length discrepancy, the height of the femoral neck cut was adjusted accordingly to compensate for the leg length discrepancy. For example, if the affected leg is 20 mm short, place the centre of the head 20 mm above the centre of the cup. Intraoperatively, the surgeon performed the femoral neck osteotomy at the level determined by preoperative templating. Postoperatively, the leg length was measured and compared to the preoperative leg length. Preoperatively, the leg length discrepancy ranged from 5 to 30 mm. In all cases, the leg was short on the side of THR (ipsilateral). Leg length discrepancy was adjusted in all THR cases. Postoperatively, the accuracy of the correction was found to be within 5 millimeters i.e. less than 5mm of shortening or lengthening). Intraoperatively, the level of femoral neck cut ranged from 1 to 44 mm. Digital templating is useful in adjusting leg length discrepancy. In addition, there were other benefits such as predication of femoral and acetabular implant sizes, restoration of normal hip centre, and optimization of femoral offset

Introduction. Low dose technology of an EOS scanner allows mechanical axis radiographs to be produced using a continuously moving x-ray emitting a thin beam to form a single image which includes all three joints, without the need for stitching. The aim of this study was to identify necessary improvements to enable effective interpretation of the radiographs, and to assess whether the quality of the radiographs varied by production method compared to a previous audit of CR and DR radiographs. Materials and Methods. 8 domains were identified based on a previous audit using the acronym MECHANIC each defining the qualities required for a radiograph to meet the criteria. 100 mechanical axis radiographs produced using conventional and digital methods were analysed in the original study to assess how many radiographs met the described criteria. The same criteria were amended and used to assess 123 different mechanical axis radiographs in the follow up study following the introduction of the EOS scanner, in which 77 were produced using EOS and 46 were produced using conventional and digital methods. Results. The second study showed improvement in 2 of the 6 domains being assessed and the result remained the same in 1 domain, with a mean change of +2%. There was a large increase in the number of radiographs with impeccable stitching in the second study due to the use of the EOS scanner. When comparing the methods of production, there were a greater percentage of EOS radiographs meeting the criteria for each domain compared to conventional and digital radiographs. Those produced using the EOS scanner had a mean 0.83% more radiographs meeting the criteria per domain. Conclusions. The overall quality of mechanical axis radiographs being produced has increased, but varies largely between the 6 domains. The EOS produced radiographs overall were of a greater quality than those produced using conventional and digital methods, but still had areas which required significant improvement

Background. Using digital X-rays to plan a hip replacement can cause problems with sizing and templating the prosthesis. Using an AP view of both hips is desirable as this allows the use of the sometimes unaffected contralateral hip for templating. Method. We devised a method of using a 20mm ball bearing as a marker positioned at the same depth as the greater trochanter, but between the patient's legs. Placing the marker between the patient's legs avoids the problem of the marker disappearing off the side of the X-ray, as is seen when placing the marker at the side of the obese patient. The marker is then used to calibrate the size of the digital X-ray. We used a hundred consecutive post-operative X-rays, comparing the size of the head of the femoral prosthesis used at surgery with the size measured pre-operatively using the marker. Results. There was a mean difference of 0, 3 mm between the size predicted using the marker and the actual prosthetic head used. Conclusion. This is an accurate and repeatable method of calibrating a digital X-ray to measure the required size of a prosthesis. NO DISCLOSURES

Introduction. The application of digital radiography in orthopaedic settings has facilitated the improvement in the retention and utilization of these images in pre and post-operative assessments [1]. In addition to the cost-effectiveness of such technology the use of digital imaging combined with advanced computer image processing software such as TraumaCadTM software system (TraumaCad, BRAINLAB, Westchester, IL, USA) can provide more accurate details about patients in total hip replacement arthroplasty (THA), a process traditionally called preoperative templating [2] by which intraoperative complications are minimized and overall surgical time is reduced[3]. In a study of 486 patients we demonstrated that patients demographic had significant effect on the outcome of the measurement and utilizing them in a predictive model had helped with improving the results [4]. In this study, we aimed to improve and optimize the proposed algorithm by utilizing more patients’ information and improving the model by using a nonlinear relationship. Our main hypothesis in this study was that the model would significantly predict the actual implant size based on the preoperative assessments. Method. We analyzed the outcome of digital radiographs of 1018 patients who were treated with THA. Minimum. Maximum. Mean. Std. Deviation. Templated Acetabulum Size. 44.00. 64.00. 54.12. 4.05. Height (m). 147.32. 202.20. 172.02. 10.73. Weight (kg). 39.10. 139.10. 84.44. 19.67. BMI. 15.48. 43.06. 28.33. 5.18. Acetabular Size. 44.00. 64.00. 54.25. 3.75. Digital radiographs were acquired in the anteroposterior view of the pelvis centered over the pubic symphysis. The hip was internally rotated 10° to 15°. We evaluated multiple interactions and nonlinear models and developed the most significant model based on the available clinical data. Results. We derived the following equation based on the model presented by the multiple regression analysis. Act[estimated]=−9.0467–0.35*Act[temp]+34.79*Height−0.35*Weight+1.32*BMI+0.01* (Act[temp])∘2–3.56*Height∘2–0.01*BMI∘2. In which Act[estimated] is the estimated size of acetabulum cup, Act[temp] is the preoperative templated acetabulum size from digital radiography, Height was in m and Weight was in kg. Figure 1 and Figure 2 depicts the residual assessments of the model. Figure 3 depicts the range of effects by each factor. Discussion. Patients’ specific data would improve the preoperative accuracy by more than 5% within one size of the actual acetabular component size. This improvement in accuracy translates into significant cost saving in THA cases as the cost of implant inventory could be significantly minimized. In our practice based on these assessments we use customized patients trays to reduce intraoperative costs