Introduction. The direct anterior approach (DAA) for total hip arthroplasty continues to gain popularity. Consequently, more procedures are being performed with the patient supine. The approach often utilizes a special leg positioner to assist with femoral exposure. Although the supine position may seem to allow for a more reproducible pelvic position at the time of cup implantation, there is limited evidence as to the effects on pelvic tilt with such leg positioners. Furthermore, the DAA has led to increased popularity of specific softwares, ie. Radlink or JointPoint, that facilitate the intra-op analysis of component position from fluoroscopy images. The aim of this study was to assess the difference in cup orientation measurements between intra-op fluoroscopy and post-op CT. Methods. A consecutive series of 48 DAA THAs were performed by a single surgeon in June/July 2018. All patients received OPS. TM. pre-operative planning (Corin, UK), and the cases were performed with the patient supine on the operating table with the PURIST leg positioning system (IOT, Texas, USA). To account for variation in pelvic tilt on the table, a fluoroscopy image of the hemi-pelvis was taken prior to cup impaction, and the c-arm rotated to match the shape of the obturator foramen on the supine AP Xray. The final cup was then imaged using fluoroscopy, and the radiographic cup orientation measured manually using Radlink GPS software (Radlink, California, USA). Post-operatively, each patient received a low dose CT scan to measure the radiographic cup orientation in reference to the supine coronal plane. Results. Mean cup orientation from intra-op fluoro was 38° inclination (32° to 43°) and 24° anteversion (20° to 28°). Mean cup orientation from post-op CT was 40° inclination (29° to 47°) and 30° anteversion (22° to 38°). Cups were, on average, 6° more anteverted and 2° more inclined on post-op CT than intra-op. These differences were statistically significant, p<0.001. All 48 cups were more anteverted on CT than intra-op. There was no statistical difference between pre- and post-op supine pelvic tilt (4.1° and 5.1° respectively, p = 0.41). Discussion. We found significant differences in cup orientation measurements performed from intra-op fluoro to those from post-op CT. This is an important finding given the attempts to adjust for pelvic tilt during the procedure. We theorise two sources of error contributing to the measurement differences. Firstly, the under-compensation for the anterior pelvic tilt on the table. Although the c-arm was rotated to match the obturator foramen from the pre-op imaging, we believe the manual matching technique utilised in the Radlink software carries large potential errors. This would have consistently led to an under-appreciation of the adjustment angle required. Secondly, the manual nature of defining the cup ellipse on the fluoro image has previously been shown to underestimate the degree of cup anteversion. These combined errors would have consistently led to the under-measurement of cup anteversion seen intra-operatively. In conclusion, we highlight the risk of over-anteversion of the acetabular cup when using 2D measurements, given the manual inputs required to determine a result

INTRODUCTION:. Stationary fluoroscopy has been a viable resource for determining in vivo knee kinematics, but limitations have restricted the use of this technology. Patients can only perform certain normal daily living activities while using stationary fluoroscopy and must conduct the activities at speeds that are slower than normal to avoid ghosting of the images. More recently, a Mobile Tracking Fluoroscopic (MTF) unit has been developed that can track patients in real-time as he/she performs various activities at normal speeds (Figure 1). Therefore, the objective of this study was to compare in vivo kinematics for patient's evaluated using stationary and mobile fluoroscopy to determine potential advantages and disadvantages for use of these technologies. METHODS:. The MTF is a unique mobile robot that can acquire real-time x-ray records of hip, knee, or ankle joint motion while a subject walks/manoeuvres naturally within a laboratory floor area. By virtue of its mechanizations, test protocols can involve many types of manoeuvres such as chair rises, stair climbing/descending, ramp crossing, walking, etc. Because the subjects are performing such actions naturally, the resulting fluoroscope images reflect the full functionality of their musculoskeletal anatomy. Patients in the study were initially fluoroscoped using a stationary unit and then using the MTF unit. RESULTS:. Initially, patients were requested to perform gait, stair-rise, stair descent, chair-rise and a deep knee bend under stationary fluoroscopy. Unfortunately, patients were not able to perform most of these activities, under normal conditions, using a stationary fluoroscopy unit. Therefore, only a deep knee bend, step-up and chair-rise were viable activities, but again, performed at slower than normal speeds. While using the MTF unit, all five activities were easily performed and patients received 50% less radiation due to the fact that five activities using the MTF required significantly less time than three activities using a stationary fluoroscopy unit (Figure 2). Also, walking up and down a ramp was also included in the protocol for the MTF analyses, leading to the inclusion of two new activities, not previously evaluated using stationary fluoroscopy. Interestingly, the kinematics for the patients using a stationary fluoroscopy unit produced less overall motion than compared to the MTF analysis, probably due to the slower speed required to perform the activities. While using the MTF unit, kinematic findings such as anteroposterior sliding and reverse axial rotation were more pronounced during each activity. DISCUSSION:. This study has revealed that there are distinct advantages for using a MTF unit, compared to a stationary unit. Patient exposure to radiation was significantly reduced and they were able to perform each activity quicker, while only one trial was required for each activity. Patients were able to perform multiple activities at normal speeds and these analyses seemed to produce more overall femorotibial motion than those assessed using a stationary fluoroscopy unit. Also, ghosting of the images, seen when using a stationary fluoroscopy unit were not evident when using the MTF. Future analyses with the MTF will involve more challenging activities, such as stop and start and sequential motion patterns

Utilization of C-arm fluoroscopy during direct anterior total hip arthroplasty (THA) is disruptive and potentially increases the risks of patient infection and cumulative surgeon radiation exposure. This pilot study evaluated changes in surgeon C-arm utilization during an initial 10 cases of direct anterior THA in which an imageless computer-assisted navigation device was introduced. This retrospective study includes data from 20 direct anterior THA cases performed by two orthopaedic surgeons (BC; SRE) in which an imageless computer-assisted navigation device was utilized (Intellijoint HIP®; Intellijoint Surgical, Waterloo, ON, Canada). Total C-arm image count was recorded in each case, and cases were grouped in sets of 5 for each surgeon. The mean C-arm image count was calculated for each surgeon, and combined C-arm image counts were calculated for the study cohort. Student's t-tests were used to assess differences. The use of intraoperative C-arm fluoroscopy decreased from a mean of 9.4 images (standard deviation [SD]: 8.6; Range: 3 – 23) to a mean of 2 images (SD: 2.9; Range: 0 – 7) for surgeon BC (P=0.10) and decreased from a mean of 10.75 images (SD: 1.2; range 9 – 12) to a mean of 6.7 images (SD: 8.3; range: 0 – 16) for surgeon SRE (P=0.36). Combined, an overall decrease in intraoperative C-arm image count from a mean of 11.3 images (SD: 6.9; range: 6 – 23) to a mean of 3.7 images (SD: 3.9; range: 0 – 8.5) was observed in the study cohort (P=0.06). The adoption of imageless computer-assisted navigation in direct anterior THA may reduce the magnitude of intraoperative C-arm fluoroscopy utilization; however further analysis is required

During a periacetabular osteotomy (PAO), intra-operative assessment of correction of acetabular parameters is typically performed using fluoroscopy of the hip, a technique that has not been shown to produce predictable measurements. Furthermore, paralysing agents are used in order to facilitate dissection and fragment mobilization. The effect of paralysing agents on spino-pelvic posture is yet to be investigated. This study aims to: 1. Compare the reliability of intra-operative x-rays versus hip fluoroscopy in the assessment of acetabular fragment correction and 2. Evaluate the effect of changes in spino-pelvic alignment on the assessment of acetabular correction. An IRB approved, retrospective review of all patients who underwent a PAO at our institution between 2006–2018 was performed. Patient demographic data was collected and all available imaging studies were retrieved. Patients were excluded if there was no available to review intra-operative AP pelvis x-ray or intra-operative fluoroscopic PA image of the hip. Using a validated hip analysis software (Hip2Norm), the lateral center edge angle (LCEA) and acetabular index (AI) of plain radiographs were measured. The sacro-femoral-pubic angle (SFP), along with the LCEA and AI of the fluoroscopic image were measured using ImageJ. A oneway ANOVA was used to detect differences between measured parameters in the intra-operative x-ray, the post-operative x-ray and the fluoroscopic image. A total of 93 patients were identified. 26 patients were excluded due to missing data. The mean LCEA in the post-operative, intra-operative, and fluoroscopic groups were as follows: 33.67° (range 5.3° to 52.4°), 30.71°(range 9° to 55.6°), and 29.23°(range 12.4° to 51.4°) respectively. The mean AI in the post-operative, intra-operative, and fluoroscopic groups were as follows: −0.65° (range −18.10° to 27.30°), 0.35°(range −16.10° to 17.20°), and 5.54°(range −11.66° to 27.83°) respectively. When comparing intra-operative to post-operative plain radiographs, there was no statistically significant difference in AI (ΔAI −1±1.29° p=0.71) or LCEA (ΔLCEA 2.95±1.38° p=0.09). When comparing fluoroscopy to post-operative plain radiographs, there was a statistically significant difference in AI (ΔAI −6.21±1.29° p < 0 .0001) as well as LCEA (ΔLCEA 4.44±1.38° p < 0 .0001). Statistical analysis revealed no influence of demographics (age, BMI, gender), on acetabular correction parameters. The mean SPF angles measured from intra-operative and post-operative x-rays were 69.32±5.11° and 70.45±5.52°. There was a statistically significant difference between these 2 measurements with a ΔSFP of 1.03° (p < 0 .0001). The results of our study show that the use of intra-operative x-ray for the assessment of LCEA and AI is more reliable than fluoroscopic images. Further, we found a difference in SFP angle, which offers an indirect assessment of pelvic tilt, between the intra-operative and the post-operative plain x-rays. This suggests that there are changes in pelvic tilt during the surgery, which can be attributed to either patient positioning or changes in spino-pelvic posture secondary to the paralysing agents used by the anesthetists. The use of intra-operative x-rays as well as the effect of paralysing agents on spino-pelvic alignment should be considered by surgeons performing PAO's

Aims. The use of fluoroscopy in orthopaedic surgery creates risk of radiation exposure to surgeons. Appropriate personal protective equipment (PPE) can help mitigate this. The primary aim of this study was to assess if current radiation protection in orthopaedic trauma is safe. The secondary aims were to describe normative data of radiation exposure during common orthopaedic procedures, evaluate ways to improve any deficits in protection, and validate the use of electronic personal dosimeters (EPDs) in assessing radiation dose in orthopaedic surgery. Methods. Radiation exposure to surgeons during common orthopaedic trauma operations was prospectively assessed using EPDs and thermoluminescent dosimeters (TLDs). Normative data for each operation type were calculated and compared to recommended guidelines. Results. Current PPE appears to mitigate more than 90% of ionizing radiation in orthopaedic fluoroscopic procedures. There is a higher exposure to the inner thigh during seated procedures. EPDs provided results for individual procedures. Conclusion. PPE currently used by surgeons in orthopaedic trauma theatre adequately reduces radiation exposure to below recommended levels. Normative data per trauma case show specific anatomical areas of higher exposure, which may benefit from enhanced radiation protection. EPDs can be used to assess real-time radiation exposure in orthopaedic surgery. There may be a role in future medical wearables for orthopaedic surgeons. Cite this article: Bone Jt Open 2022;3(11):907–912

2D/3D image registration techniques have supplanted RSA for kinematic analysis as they are faster, non-invasive and enable pre and post op studies. Improved algorithms have solved the problem of accuracy of out-of-plane translation [1,2]. The aim of this study is to apply these new algorithms to the post op case. In this study, Computer-Aided Design (CAD) models of the femoral and tibial components were registered to fluoroscopic images. The prosthesis (RBK knee, Global Orthopaedic Technology), was implanted into a sawbones knee. A perspex cage held the knee static while simultaneous fluoroscopy and dual X-rays were taken from 0 and 90 degrees flexion. Translations orthogonal to the fluoroscope were simulated by sliding the cage at 5 mm intervals. The CAD models were then registered with the fluoroscopy frames. Registration information was used to perform kinematic analysis. This study has demonstrated greater accuracy for the post operative than pre-operative registration applications. The standard deviation of error for flexion/extension was 0.23° with respect to RSA. The average standard deviation of error for out-of-plane rotations (i.e. abduction/adduction and internal/external rotation) was 0.46°. Translations such as anterior-posterior drawer, compression/distraction and medio-lateral shift had errors of 0.16 mm, 0.17 mm and 0.59 mm, respectively. Both the registration and kinematic analysis accuracies for prosthesis components were superior to those for registration of natural (e.g. cadaver) bones [1]. While rotation accuracies improved about 0.1°, improvement in translation was substantial. In particular, medio-lateral translation accuracy has improved from 1 mm (in our previous study) to 0.59 mm, which is promising. It is worth noting that the best reported accuracy for out-of-plane or medio-lateral translation has been 1.03 mm [2]. Hence, this technique is competitive with other 3D/2D registration methods reported in the literature. Our experiments show that our 3D CAD to 2D fluoroscopy registration method is sufficiently accurate to produce confident and reliable analysis of prospective kinematics studies

Aim. The purpose of this study was to establish the diagnostic utility and spectrum of fluoroscopy guided percutaneous transpedicular biopsies of the thoraco-lumbar spine performed at our institution and to review some aspects regarding the diagnosis of spinal tuberculosis (TB). Methods. A retrospective study was performed on a consecutive series of 48 patients who underwent fluoroscopy guided percutaneous transpedicular biopsies of the spine performed at our institution. Biopsy specimens were sent for microscopy, culture and sensitivity (MC&S) as well as for TB microscopy, culture and polymerase chain reaction (PCR) and for histology. Results. There were 26 females and 22 males. The ages ranged from 23 to 79 years with a mean of 47 years. Fifteen biopsies were performed in the thoracic spine and 33 in the lumbar spine. A diagnosis was established in 83% of patients. The most common diagnosis, made in 58% of cases, was TB. The second most common diagnosis was metastatic disease, diagnosed in 15%. In 3 patients a diagnosis was made of concomitant TB and metastatic adenocarcinoma. No complications were encountered. Regarding the diagnosis of spinal TB we found that microscopy for alcohol and acid fast bacilli has a very low yield, with TB cultures, PCR and histology delivering a higher yield. TB PCR was also found to be positive in some cases where the TB cultures were negative which had implications for our institution's protocol regarding performance of TB PCR testing. Conclusion. Fluoroscopy guided percutaneous transpedicular biopsies of the thoraco-lumbar spine is a safe and effective tool in the diagnostic work-up of a patient with a spinal lesion of uncertain cause. We recommend that in all cases specimens should be send for histology and bacteriological studies and if spinal TB is suspected samples should be sent for histology, MC&S and PCR. NO DISCLOSURES

Purpose. Measurements of patellar kinematics are essential to investigate the link between anterior knee pain following knee arthroplasty and patellar maltracking. A major challenge in studying the patellofemoral (PF) joint postoperatively is that the patellar component is only partially visible in the sagittal and close-to-sagittal radiographs. The narrow angular distance between these radiographs makes the application of conventional bi-planar fluoroscopy impossible. In this study a methodology has been introduced and validated for accurate estimation of the 3D kinematics of the PF joint post-arthroplasty using a novel multi-planar fluoroscopy approach. Method. An optoelectronic camera (Optotrak Certus) was used to track the motion of an ISO-C fluoroscopy C-arm (Siemens Siremobil) using two sets of markers attached to the X-ray source and detector housings. The C-arm was used in the Digital Radiography (DR) mode, which resembles an ordinary X-ray fluoroscopy image. A previously-developed technique (Cho et al., 2005; Daly et al., 2008) was adapted to find the geometric parameters of the imaging system. Thirty-eight DRs of the calibration phantom were obtained for the 190 of rotation of the C-arm at 5 rotational increments while data from motion markers were recorded continuously at a frequency of 100 Hz. A total knee replacement prosthesis was implanted on an artificial bone model of the knee, and the implant components and bones were rigidly fixed in place using a urethane rigid foam. For the purpose of validation, positions of the implant components were determined using a coordinate measuring machine (CMM). Sagittal and obliquely sagittal radiographs of the model were taken where the patellar component was most visible. For each DR the geometric parameters of the system were interpolated based on the location of the motion markers. The exact location of the projection was then determined in 3D space. JointTrack Bi-plane software (Dr. Scott Banks, University of Florida, Gainesville) was used to conduct 2D-3D registration between the radiographs and the reverse-engineered models of the implant components. Results of the registration were directly compared to the ground-truth obtained from the CMM to calculate the accuracies. Results. The accuracies for the PF were found to be 0.48 mm and 1.32 for position and orientation of the components. For the tibiofemoral joint these values were found to be 0.89 mm and 1.43, respectively. Conclusion. The multi-planar method can be used to assess the sequential kinematics of the patellofemoral and tibiofemoral joints including the mediolateral translation and tilt of the patellar component, which are obscured in standard 2D sagittal measurements and are not possible using the traditional bi-planar setup. A limitation is that it can only be used for static imaging of the joint. It has the advantage of a relatively low radiation dose. This methodology can be used to investigate the relationship between maltracking of the patella and anterior knee pain as well as other postoperative complications

Purpose. Femoral shaft fractures are routinely treated using antegrade intramedullary nailing under fluoroscopic guidance. Malreduction is common and can be due to multiple factors. Correct entry point identification can help minimize malreduction and the risk of iatrogenic fracture. This study aims to compare landmark identification used to guide nail entry, the piriformis fossa (PF) and the trochanteric tip (T), via computer navigation and conventional fluoroscopy. Method. The location of the PF and T were digitized under direct visualization with a three-dimensional scribe on ten, fresh-frozen cadaveric right femora (two male, eight female) by three fellowship trained orthopaedic surgeons. To estimate inter- and intraobserver reliability of the direct measurements, an intraclass correlation coefficient was calculated with a minimum of two weeks between measurements. Under navigation, each specimen was draped and antero-posterior (AP) and lateral radiographs of the proximal femur were taken with a c-arm and image intensifier. The c-arm was positioned in a neutral position (0 for AP, 90 for lateral) and rotated in 5 increments, yielding a range of acceptable images. Images, in increments of 5, within the AP range (with a neutral lateral) were loaded into a navigation system (Stryker, MI). A single surgeon digitized the T and PF directly based on conventional fluoroscopy, and again directed by navigation, yielding two measurements per entry point per specimen. This was repeated for the lateral range. Hierarchical linear modelling and a Wilcox rank test were used to determine differences in accuracy and precision, respectively, in the identification of PF and T using computer navigation vs. conventional fluoroscopy. Results. The average range of suitable images for both the AP and lateral images was 29 (range of 25 to 30). The location of the PF and T was found to be reliable for a single observer (0.98 and 0.99) and between observers (0.96 and 0.93). Similar accuracy was found in identifying PF under navigation and fluoroscopy (0.05 to 1.4 cm and 0.1 to 1.5 cm respectively, p = 0.26), whereas improved accuracy was found for T using fluoroscopy (0.07 to 2.5 cm) as compared to navigation (0.2 to 2.2 cm, p < 0.001). For both the PF and T, the navigation-based points had greater precision than those selected by fluoroscopy alone (p = 0.001 and p = 0.024). Conclusion. The ideal entry point, under direct visualization, was highly repeatable, indicating that the surgeons could identify their targeted point of entry for both the PF and T. However, there is an arc of approximately 30, through which acceptable AP and lateral images can be obtained. Throughout this range, the location of the PF and T can vary up to 1.5 and 2 cm, respectively. Navigation was less accurate than fluoroscopy in the T selection, yet had greater precision for both points. Thus, while navigation may decrease accuracy in selection of the T, it is more repeatable overall and equally accurate in selecting the PF

Purpose:. To materialize 3D kinematic analysis of total knee arthroplasty (TKA), 2D/3D registration techniques, which use X-ray fluoroscopic images and the knee implants CAD, have been applied to clinical cases. However, most conventional methods have needed time-consuming and labor-intensive manual operations in some process. In previous study, we addressed a manual operations problem when setting initial pose of implants model for 2D/3D registration, and reported a semi-automated initial pose estimation method based on an interpolation technique. However, this method still required appropriate initial pose estimation of the model with manual operations for some X-ray images (key frames). Additionally, in the situation like fast knee motion and use of low frame rate, good registration results were not obtained because of the large displacement between each frame silhouette. To overcome these problems, this study proposes an improved semi-automated 3D kinematic estimation method. Methods:. Our 2D/3D registration technique is based on a robust feature-based algorithm. In improved initial pose estimation method, for the only first frame, the initial pose is manually adjusted as close as possible. That is, we automatically estimate appropriate initial pose of the model for X-ray images except for the first frame. To automatically estimate the initial pose of the model, we utilize a transformation with feature points extracted from the previous and next frames. A transform matrix which has three DOF (translations parallel to the image, and a rotation perpendicular to the image) is calculated by registration of corresponding feature points between the previous and next frame extracted with SURF algorithm. While, the corresponding point sets extracted by SURF sometimes include some error sets. Therefore, in this study, LmedS method was employed to detect the error corresponding sets and calculate a transform matrix accurately. In Fig. 1(a) and (b), the orange square shows the region defined with the boundary box of the model, and some lines show the combined corresponding point sets. The blue lines are correct corresponding point sets, and the pink lines are error corresponding point sets detected with LmedS method. Finally, 3D pose of the model estimated in previous frame is transformed with accurately calculated transform matrix, and the transformed pose is used as an initial 3D pose of the model in next frame. Experimental results:. To validate the feasibility of the improved semi-automated 3D kinematic estimation method, experiments using X-ray fluoroscopic images of 4 TKA patients during knee motions were performed. In order to assess the performance of the improved method, automation rate was calculated, and the rate was defined as the X-ray frame number of satisfying clinical required accuracy (error within 1 mm, 1 degree) relative to all X-ray frame number. As results of the experiments, 3D pose of the model for all X-ray images except for the first frame is automatically stably-estimated, the automation rate of the femoral and tibial component were 83.7% and 73.5%, respectively. Conclusions:. The present method doesn't need labor-intensive manual operations for 3D kinematic estimation of TKA, and is thought to be very helpful for practical clinical applications

We have used CT-based total hip navigation system from 2003, to set the acetabular socket in optimal position. At first, we had used CT-based land-mark matching system. It needs matching procedure during surgery, touching paired points in surgical exposure. From 2006, we started to use new navigation system, called CT-based fluoroscopy-matching system, which was developed by BrainLAB Company (Vector-vision 2.7.1., 3.5.1.). For this new system, pre-surgical image matching procedure is need. Fluoroscopic images with 2 different directions must be taken in operation room. Then fluoroscopic images and CT reconstructive images were matched in computer with special program. Matching procedure was done before surgical incision. We compared the advantage of these two systems about technical problem, radiation exposure, time need for procedure, and accuracy. And then we discussed how to use these two different systems for THA patients. Accuracy was compared for 241 THA patients using these navigation systems. 152 cases were with CT-based land-mark matching system and 89 patients with CT-based fluoroscopy matching system. Final verification angle of acetabular socket setting in navigation during surgery was recorded for each case. The operative angle, which is referred from Murray, is used to show the socket setting angle (inclination and anteversion) in these navigation systems. Post-operative CT scan was taken to evaluate the actual socket setting angle. The values between verification angle during surgery and post-operative CT measured angle were calculated and compared statistically. Results were followed. New CT-based fluoroscopy matching method (F method): Average setting angle (operative angle) of socket in these 89 cases were 42.9 +/− 5.1 degree in inclination angle, and 28.5 +/− 7.9 degree in anteversion angle. The absolute difference in 89 cases between final verification angle and post-operative CT measurement angle was 2.9 degree (on average) +/− 2.5 degree in inclination angle, and 2.8 degree (on average) +/− 2.6 degree in anteversion angle. Conventional CT-based land-mark matching method (L method): The absolute difference in 152 cases between final verification angle and post-operative CT measurement angle was 4.2 degree (on average) +/− 3.2 degree in inclination angle, and 4.4 degree (on average), +/− 3.7 degree in anteversion angle. Absolute differences of setting angle in fluoroscopy matching groups showed statistically low compared with land-mark matching groups (P<0.01). Technical problems: L method is difficult to learn actual procedure. F method is easy to learn procedure. Image matching was done automatically by computer program. Radiation exposure during surgery: L method needs no additional radiation. F method needs radiation to get 2 fluoroscopic images. Total amount time need for navigation: L method needs extra 10 minutes during surgery in case of skilled-doctor. F method needs extra 20 minutes before starting surgery in case of all kind doctors. The accuracy of acetabular socket setting: Absolute errors in socket setting with theses two systems were within 5 degree together on average. These results showed the usefulness of both systems. Compared the accuracy between these 2 systems, F methods showed high accuracy. The accuracy of F methods is always high. It has no influence with deformity around hip joint, because fluoroscopic image matching was done with lower part of pubic bone, especially around symphysis pubis. For ordinary THA cases with skilled-doctor, CT-based land-mark matching system is useful, because this system is very convenient and needs only extra 10 minutes during surgery. For severe deformed cases with all kind doctors, CT-based fluoroscopy matching system is useful, because this system showed high accuracy even for severe deformed cases. Before surgical incision, fluoroscopic matching procedure has finished. This system needs no extra time after surgery starts

The mobile-bearing variant of a single-radius design is assumed to provide more freedom of motion compared to the fixed-bearing variant because the insert does not restrict the natural movements of the femoral component. This would reduce the contact stresses and wear which in turn may have a positive effect on the fixation of the prosthesis to the bone and thereby decreases the risk for loosening. The aim of this prospective randomized study was to evaluate early migration of the tibial component and kinematics of a mobile-bearing and fixed-bearing total knee prosthesis of the same single-radius design. According to a prospective randomized protocol 20 Triathlon single-radius posterior- stabilized knee prostheses were implanted (9 mobile-bearing and 11 fixed-bearing). Fluoroscopy and roentgen stereophotogrammetric analysis were performed 6 and 12 months post-operatively. The 1 year post-operative roentgen stereophotogrammetric analysis results showed considerable early migrations in 3 mobile-bearing patients and 1 fixed-bearing patient. The range of knee flexion was the same for the mobile-bearing and fixed- bearing group. The mobile insert was following the femoral component during motion. This study showed no apparent distinction in early migration and kinematics between mobile-bearing and fixed-bearing single-radius total knee prostheses. Des- pite the mobile insert was following the femoral component during motion, and therefore performed as intended, no kinematic advantages of the mobile-bearing total knee prosthesis were seen. It is concluded that a mobile insert in single-radius total knee prostheses is redundant and will not lead to additional benefits

Introduction

Historically, knee implants have been designed using average patient anatomy and despite excellent implant survivorship, patient satisfaction is not consistently achieved. One possibility for this dissatisfaction relates to the individual patient anatomic variability. To reduce this inter-patient variability, recent advances in imaging and manufacturing have allowed for the implementation of patient specific posterior cruciate retaining (PCR) total knee arthroplasty (TKA). These implants are individually made based on a patient's femoral and tibial anatomy determined from a pre-operative CT scan. Although in-vitro studies have demonstrated promising results, there are few studies evaluating these implants in vivo. The objective of this study was to determine the in vivo kinematics for subjects having a customized, individually made(CIM) knee implant or one of several traditional, off-the-shelf (OTS) TKA designs.

When a suspicious spine lesion is identified, an accurate diagnosis based on tissue biopsy is needed to direct towards the correct treatment protocol. Several studies concluded that the percutaneous fluoroscopy guided biopsy of vertebral lesions is a safe, effective and accurate diagnostic tool and is preferred over open techniques when possible. The aim of this study was to review percutaneous fluoroscopy guided transpedicular spinal biopsies at a tertiary hospital over a 6-year period. The research design was a retrospective review of patients who underwent percutaneous transpedicular spinal biopsies under fluoroscopy guidance at a tertiary hospital over a six year period (1st January 2016 to the 31st December 2021). The spine theatre registry and hospital records system were used as the source for data collection. Statistical analysis was conducted to determine the effectiveness of transpedicular spinal biopsies, compare spinal pathology amongst age and gender and to identify any complications. The study analysed 180 biopsies, 120 yielding a positive result (66.67%). Of these 8.9% were pyogenic infection, 18.4% neoplasm, 36.7% Tuberculosis and 2.7% other. There were 75 males and 105 females with an age range between 9 and 86 years and mean age of 43.44. Comparing age and gender found no statistical significance (p = 0.778). Comparing biopsy result and gender showed no statistical significant relationship (p = 0.970). Comparison of biopsy result with age showed no statistical significant association (p = 0,545). Four complications were identified (2.22%). The study showed that fluoroscopy guided percutaneous transpedicular biopsy is an effective and safe modality in obtaining spinal specimens in all age groups for a wide spectrum of spinal pathological lesions

Abstract. INTRODUCTION. With increasing use of fluoroscopy in Orthopaedic theatres in recent years, the occupational radiation exposure to the surgeons and the theatre staff has increased significantly. Thyroid is one of the most radio-sensitive tissues in the body, but there is a clear lack of awareness among theatre staff of risks of radiation to thyroid. METHODS. We prospectively reviewed the use of thyroid shield by the theatre staff in the orthopaedic theatre for two weeks period. We also recorded the number of fluoroscopic images taken and total radiation dosage for each case. RESULTS. Our results showed that of 249 staff in the theatres of which, only 35 people (14.2%) wore thyroid shields during fluoroscopy, whereas 100% were complaint with body protection shield. We noticed that only 30% of the surgeons, 40% of the scrub nurses and 5% anaesthetist use this, while 95% of the radiographers uses thyroid protection in theatre. Average total radiation during upper-limb procedures was 1.25 cGy, during lower-limb procedures it was 43.48 cGy. Total radiations were very high particularly during lower-limb nailing procedures (80.98 cGy). CONCLUSION. Extensive use of fluoroscopy has a stochastic effect (accumulative effect) on thyroid gland particularly, if the dose in higher than 65 cGy. Despite its availability, only 14% people use the thyroid protection shield. We must emphasise the use of thyroid protection shield to the Orthopaedic surgeons, particularly during lower-limb procedures

Abstract. Background. Anterior cruciate ligament (ACL) injuries with coinciding posterolateral tibial plateau (PLTP) depression fractures are rare. According to the most up to date literature, addressing the PLTP is crucial in preventing failure of the ACL. However, the surgical management of these injuries pose a great challenge to orthopaedic surgeons, given the anatomical location of the depressed PTP fragment. We report a case of a 17-year-old patient presenting to our department with this injury and describe a novel fixation method, that has not been described in the literature. Surgical Technique. A standard 2-portal arthroscopy is used to visualise the fractures. The PLTP is addressed first. With the combined use of arthroscopy and fluoroscopy, a guide pin is triangulated from the anteromedial aspect of the tibia, towards the depressed plateau fragment. Once the guide pin is approximately 1cm from the centre of the fragment, it is over-drilled with a cannulated drill, and simultaneously bluntly punched up to its original anatomical location. Bone graft is then used to fill the void, supported by two subchondral screws. Both fluoroscopy and arthroscopy are used to confirm adequacy of fixation. Finally, the tibial spine avulsion fracture is repaired arthroscopically using the standard suture bridging technique. Conclusion. We describe a novel, one-stage, minimally invasive approach that addresses both the ACL injury and PLTP fracture. We highlight the advantages of utilising this approach and functional outcomes

Background. Dynamic Hip Screw (DHS) is the most frequently used implant in management of intertrochanteric femoral fractures. There is a known statistical relationship between a tip-apex distance (TAD) >25mm and higher rate of implant failure. Our aim was to analyse all DHS procedures performed in our trust from seventeen months and compare their TAD values to the acceptable standard of ≤25mm. Methods. All patients undergoing DHS between April 2020-August 2021 were identified from our theatre system. Additionally, those presenting to hospital with implant failures were included. Patient demographics, date of surgery, fracture classification (AO) and date/mode of failure were recorded. Intraoperative fluoroscopy images were reviewed to calculate TAD, screw location and neck shaft angles by two independent observers. Results. 215 patients were identified, five of which were excluded due to inadequate fluoroscopy. Failure was seen in 3.3% of the cohort (n=7), of which 71.4% had an unacceptable TAD. In total, 21 patients (10%) had TAD >25mm, of whom 12 had superiorly and 15 had posteriorly placed screws. There were no failures in patients with a TAD of <20mm whereas a TAD >30mm had 50% failure rate. Conclusion. This audit reinforces the importance of aiming for a low TAD (preferably <20mm) intraoperatively. It is also desirable to avoid superiorly and significantly posteriorly placed screws. Implications. Complex hip revision surgery in the elderly bears substantial financial implications to the NHS and, more importantly, causes prolonged morbidity to the patient. Adhering to established standards will ensure reduced implant failure and best patient care

Tibial plateau fracture reduction involves restoration of alignment and articular congruity. Restorations of sagittal alignment (tibial slope) of medial and lateral condyles of the tibial plateau are independent of each other in the fracture setting. Limited independent assessment of medial and lateral tibial plateau sagittal alignment has been performed to date. Our objective was to characterize medial and lateral tibial slopes using fluoroscopy and to correlate X-ray and CT findings. Phase One: Eight cadaveric knees were mounted in extension. C-arm fluoroscopy was used to acquire an AP image and the C-arm was adjusted in the sagittal plane from 15° of cephalad tilt to 15 ° of caudad tilt with images captured at 0.5° increments. The “perfect AP” angle, defined as the angle that most accurately profiled the articular surface, was determined for medial and lateral condyles of each tibia by five surgeons. Given that it was agreed across surgeons that more than one angle provided an adequate profile of each compartment, a range of AP angles corresponding to adequate images was recorded. Phase Two: Perfect AP angles from Phase One were projected onto sagittal CT images in Horos software in the mid-medial compartment and mid-lateral compartment to determine the precise tangent subchondral anatomic structures seen on CT to serve as dominant bony landmarks in a protocol generated for calculating medial and lateral tibial slopes on CT. Phase Three: 46 additional cadaveric knees were imaged with CT. Tibial slopes were determined in all 54 specimens. Phase One: Based on the perfect AP angle on X-ray, the mean medial slope was 4.2°+/-2.6° posterior and mean lateral slope was 5.0°+/-3.8° posterior in eight knees. A range of AP angles was noted to adequately profile each compartment in all specimens and was noted to be wider in the lateral (3.9°+/-3.8°) than medial compartment (1.8°+/-0.7° p=0.002). Phase Two: In plateaus with a concave shape, the perfect AP angle on X-ray corresponded with a line between the superiormost edges of the anterior and posterior lips of the plateau on CT. In plateaus with a flat or convex shape, the perfect AP angle aligned with a tangent to the subchondral surface extending from center to posterior plateau on CT. Phase Three: Based on the CT protocol created in Phase Two, mean medial slope (5.2°+/-2.3° posterior) was significantly less than lateral slope (7.5°+/-3.0° posterior) in 54 knees (p<0.001). In individual specimens, the difference between medial and lateral slopes was variable, ranging from 6.8° more laterally to 3.1° more medially. In a paired comparison of right and left knees from the same cadaver, no differences were noted between sides (medial p=0.43; lateral p=0.62). On average there is slightly more tibial slope in the lateral plateau than medial plateau (2° greater). However, individual patients may have substantially more lateral slope (up to 6.8°) or even more medial slope (up to 3.1°). Since tibial slope was similar between contralateral limbs, evaluating slope on the uninjured side provides a template for sagittal plane reduction of tibial plateau fractures

Introduction. Current methodologies for designing and validating existing THA systems can be expensive and time-consuming. A validated mathematical model provides an alternative solution with immediate predictions of contact mechanics and an understanding of potential adverse effects. The objective of this study is to demonstrate the value of a validated forward solution mathematical model of the hip that can offer kinematic results similar to fluoroscopy and forces similar to telemetric implants. Methods. This model is a forward solution dynamic model of the hip that incorporates the muscles at the hip, the hip capsule, and the ability to modify implant position, orientation, and surgical technique. Muscle forces are simulated to drive the motion, and a unique contact detection algorithm allows for virtual implantation of components in any orientation. Patient-specific data was input into the model for a telemetric subject and for a fluoroscopic subject. Results. For both stance and swing phase, the model predicted similar patterns and magnitudes compared to telemetry (forces) and fluoroscopy (kinematics). During stance phase, the model predicts 2.5 xBW of maximum hip force while telemetry predicts 2.3 xBW, yielding 8.7% error (Figure 1a). During swing phase, the model predicts 1.1 xBW maximum hip force, similar to telemetry (Figure 1b). During stance phase, the model predicts 1.3mm of hip separation (sliding) compared to 1.6mm for fluoroscopy, yielding 18.8% error (Figure 1c). During swing phase, the model predicts 1.9mm of separation compared to 1.7mm for fluoroscopy, yielding 11.8% error (Figure 1d). The model was also used to assess component placement, version, and optimal positioning compared to live surgery, producing very promising results. Conclusion. The model has proven accurate in predicting kinematics and forces. Therefore, forward solution mathematical modeling can be used to efficiently evaluate new component designs, positioning and technique differences, patient-specific scenarios, and any specific contribution towards THA outcomes that cannot be controlled in vivo. For any figures or tables, please contact the authors directly

Introduction. Forward solution joint models (FSMs) can be powerful tools, leading to fast and cost-efficient simulation revealing in vivo mechanics that can be used to predict implant longevity. Unlike most joint analysis methods, mathematical modeling allows for nearly instantaneous evaluations, yielding more rapid surgical technique and implant design iterations as well as earlier insight into the follow-up outcomes used to better assess potential success. The current knee FSM has been developed to analyze both the kinematics and kinetics of commercial TKA designs as well as novel implant designs. Objective. The objective of this study was to use the knee FSM to predict the condylar translations and axial rotation of both fixed- and mobile-bearing TKA designs during a deep knee bend activity and to compare these kinematics to known fluoroscopy evaluations. Methods. The knee joint is modeled mathematically using Kane's dynamics, incorporating muscle controllers to predict the muscle forces, contact detection algorithms to compute the knee joint forces, and nonlinear ligaments at the knee joint. The tibiofemoral kinematics data for 20 subjects implanted with fixed-bearing (FB) PS TKA and 20 subjects implanted with mobile-bearing (MB) PS TKA were collected using fluoroscopy data during a deep knee bend (DKB) activity from full extension to 120° of flexion. All subjects were implanted by the same surgeon. The same CAD models for these implanted were incorporated in the FSM to predict the tibiofemoral kinematics. The average component placement from fluoroscopy data were used as an initial condition for the placement of the component in the mathematical model. Results. Overall, fluoroscopy results showed patients experienced 6.8 mm and 6.4 mm posterior rollback of the lateral femoral condyle for FB and MB PS TKA groups, respectively. The FSM predicted 5.9 mm and 6.3 mm of lateral posterior rollback for FB and MB PS TKA models, respectively (Figure 1). On average, media condyle translated posteriorly −2.9 mm and −2.5 mm, for FB and MB subjects, respectively. The mathematical model prediction for FB and MB models was −1.4 mm and −2.4 mm, respectively (Figure 2). The overall axial rotation was 5.1° and 4.5°, for FB and MB subjects from fluoroscopy, respectively. The axial rotation prediction using the FSM was 6.0° and 4.2°, for FB and MB models, respectively (Figure 3). Conclusion. Overall, it is clear that the FSM can accurately predict both the patterns and magnitudes of fixed- and mobile-bearing TKA condylar translations and axial rotations, showing consistent rollback of the lateral condyle, less translation of the medial condyle, and consistent axial rotation throughout flexion, all of which were also observed in the fluoroscopy data. The correlation between the theoretically predicted and experimentally confirmed kinematic patterns demonstrates the viability of forward solution modeling as a valuable and accurate method to evaluate total joint replacement mechanics. For any figures or tables, please contact the authors directly