Introducing a pharmacist-led transmural care program to reduce drug-related problems in orthogeriatric patients: a prospective interventional study.

BACKGROUND: Orthogeriatric patients have an increased risk for complications due to underlying comorbidities, chronic drug therapy and frequent treatment changes during hospitalization. The clinical pharmacist (CP) plays a key role in transmural communication concerning polypharmacy to improve continuity of care by the general practitioner (GP) after discharge. In this study, a pharmacist-led transmural care program, tailored to orthogeriatric patients, was evaluated to reduce drug related problems (DRPs) after discharge. METHODS: An interventional study was performed (pre-period: 1/10/2021-31/12/2021; post-period: 1/01/2022-31/03/2022). Patients (≥ 65 years) from the orthopedic department were included. The pre-group received usual care, the post-group received the pharmacist-led transmural care program. The DRP reduction rate one month after discharge was calculated. Associated factors for the DRP reduction rate were determined in a multiple linear regression analysis. The GP acceptance rate was determined for the proposed interventions, as well as their clinical impact using the Clinical, Economic and Organizational (CLEO) tool. Readmissions one month after discharge were evaluated. RESULTS: Overall, 127 patients were included (control n = 61, intervention n = 66). The DRP reduction rate was statistically significantly higher in the intervention group compared to the control group (p < 0.001). The pharmacist's intervention was associated with an increased DRP reduction rate (+ 1.750, 95% confidence interval 1.222-2.278). In total, 141 interventions were suggested by the CP, of which 71% were accepted one month after discharge. In both periods, four patients were readmitted one month after discharge. 58% of the interventions had a clinical impact (≥ 2 C level using the CLEO-tool) according to the geriatrician and for the CP it was 45%, indicating that they had the potential to avoid patient harm. CONCLUSIONS: The pharmacist-led transmural care program significantly reduced DRPs in geriatric patients from the orthopedic department one month after discharge. The transmural communication with GPs resulted in a high acceptance rate of the proposed interventions.

Financial implications of the renewed reimbursement system of total hip arthroplasty in Belgium.

In Belgium, from June 1st 2018 on, a renewed reim- bursement for hip arthroplasty implants was launched and from January 1st 2019 on, a lump sum covering doctors' fees for "low variable patients", was introduced. We investigated the impact of both reimbursement systems on the funding of a University Hospital in Belgium. All patients from the UZ Brussel with a severity of illness score of one or two whom had an elective total hip replacement implanted between January 1st and May 31st 2018, were included retrospectively. We compared their invoicing data to those of patients operated in the same period but one year later. Moreover, we simulated the invoicing data of both groups as if they had been operated in the other period. Overall, we compared invoicing data of 41 patients before and 30 after the introduction of both renewed reimbursement systems. After the introduction of both new laws, we noted a loss of funding per patient and per intervention between 46.8€ and 753.5€ for a single room and, between 105.5€ and 1877.7€ for a double room. We noted the highest loss in the subcategory "physicians' fees". The renewed reimbursement system is not "budget neutral". In time, the new system can lead to an optimization of care, but it can also lead to a progressive decrease of funding if future fees and implant reimbursements would be aligned towards the national mean. More- over, we fear the new financing system could affect the quality of care and/or result in the selection of profitable patients.

Augmented Reality-Assisted Neurosurgical Drain Placement (ARANED): Technical Note.

BACKGROUND: Many surgical procedures, such as placement of intracranial drains, are currently being performed blindly, relying on anatomical landmarks. As a result, accuracy results still have room for improvement. Neuronavigation could address this issue, but its application in an urgent setting is often impractical. Augmented reality (AR) provided through a head-worn device has the potential to tackle this problem, but its implementation should meet physicians' needs. METHODS: The Surgical Augmented Reality Assistance (SARA) project aims to develop an AR solution that is suitable for preoperative planning, intraoperative visualisation and navigational support in an everyday clinical setting, using a Microsoft HoloLens. RESULTS: Proprietary hardware and software adaptations and dedicated navigation algorithms are applied to the Microsoft HoloLens to optimise it specifically for neurosurgical navigation. This includes a pipeline with an additional set of advanced, semi-automated algorithms responsible for image processing, hologram-to-patient registration and intraoperative tracking using infrared depth-sensing. A smooth and efficient workflow while maintaining high accuracy is prioritised. The AR solution provides a fully integrated and completely mobile navigation setup. Initial preclinical and clinical validation tests applying the solution to intracranial drain placement are described. CONCLUSION: AR has the potential to vastly increase accuracy of everyday procedures that are frequently performed without image guidance, but could still benefit from navigational support, such as intracranial drain placements. Technical development should go hand in hand with preclinical and clinical validation in order to demonstrate improvements in accuracy and clinical outcomes.

The effect of augmented reality on the accuracy and learning curve of external ventricular drain placement.

OBJECTIVE: The traditional freehand technique for external ventricular drain (EVD) placement is most frequently used, but remains the primary risk factor for inaccurate drain placement. As this procedure could benefit from image guidance, the authors set forth to demonstrate the impact of augmented-reality (AR) assistance on the accuracy and learning curve of EVD placement compared with the freehand technique. METHODS: Sixteen medical students performed a total of 128 EVD placements on a custom-made phantom head, both before and after receiving a standardized training session. They were guided by either the freehand technique or by AR, which provided an anatomical overlay and tailored guidance for EVD placement through inside-out infrared tracking. The outcome was quantified by the metric accuracy of EVD placement as well as by its clinical quality. RESULTS: The mean target error was significantly impacted by either AR (p = 0.003) or training (p = 0.02) in a direct comparison with the untrained freehand performance. Both untrained (11.9 ± 4.5 mm) and trained (12.2 ± 4.7 mm) AR performances were significantly better than the untrained freehand performance (19.9 ± 4.2 mm), which improved after training (13.5 ± 4.7 mm). The quality of EVD placement as assessed by the modified Kakarla scale (mKS) was significantly impacted by AR guidance (p = 0.005) but not by training (p = 0.07). Both untrained and trained AR performances (59.4% mKS grade 1 for both) were significantly better than the untrained freehand performance (25.0% mKS grade 1). Spatial aptitude testing revealed a correlation between perceptual ability and untrained AR-guided performance (r = 0.63). CONCLUSIONS: Compared with the freehand technique, AR guidance for EVD placement yielded a higher outcome accuracy and quality for procedure novices. With AR, untrained individuals performed as well as trained individuals, which indicates that AR guidance not only improved performance but also positively impacted the learning curve. Future efforts will focus on the translation and evaluation of AR for EVD placement in the clinical setting.

Introduction of the orthogeriatric co-management model increases the quality of care : a pilot study.

Traditionally, geriatric patients with musculoskeletal or osteoarticular problems will be admitted to an orthopedic ward and will be treated by sur- geons. However, these patients often suffer from comorbidities requiring geriatric management. In this study, the orthogeriatric co-management (OG- CM) model is compared to traditional orthopedic care model in a retrospective pilot study. In this study, two patients groups were compared during two similar time periods : (1) Group 1 consisted of 119 geriatric patients admitted to an orthopedic (trauma) ward who were treated, with conventional geriatric care on demand (before OG- CM ; October 1-December 31, 2013) and (2) Group 2 consisted of 132 geriatric patients who were admitted after the implementation of the OG-CM model (after OG-CM ; October 1-December 31, 2014). Outcomes measured were : quality of care outcome, mortality and costs. After the introduction of OG-CM, the number of diagnoses increased (P = 0.011) adjusting for sex, age, length of stay (LOS), urgency and getting surgery (yes/ no). However, this did not lead to a significant higher severity of illness (SOI). The number of readmissions within a year were significantly lower after OG-CM (0.31 per patient) compared to before OG-CM (0.89 per patient) (P < 0.001). No significant difference in in-house and reported mortality after 3 months was observed. Costs increased, but no significant differences were found. The OG-CM model demonstrated an increase in quality of care. This was indicated by an increased number of medical diagnoses resulting in having less readmissions, without affecting the mortality rates and the LOS. Future randomized multi-centered studies are required to enable causal relationships.

Custom-made triflanged acetabular components in the treatment of major acetabular defects. Short-term results and clinical experience.

We report on the Belgian experience with the aMace® custom-made triflange acetabular component in revision total hip arthroplasty between September 2009 and November 2014. We focused on (1) the complexity of the preoperative planning and reimbursement procedure; (2) the surgical problems and operative experience; and (3) the early outcome. We collected 20 patients' reviews and 22 surgeons' reviews, with a mean follow-up of 25 months. The preoperative planning and reimbursement procedures were rated as time-consuming and cumbersome. In 6/22 cases, the operation was difficult or very difficult. Technical problems occurred in 8/22 cases, including problematic fitting in four. However, all aMace® components could be implanted successfully. The mean postoperative Harris Hip Score (HHS) was 68/100; patients' satisfaction was high and most patients experienced no or mild pain. Complications occurred in 8/22 cases, half of them dislocations. The aMace® implant can provide a solution for complex acetabular revisions. As dislocations were common, the use of dual-mobility cups should be considered. Because of the high cost and the lack of bone stock restoration, we suggest using custom-made triflange acetabular implants only in cases with large cavitational and segmental defects, which would be difficult to reconstruct with alternative methods.

The TRAC-PS dual radius total knee arthroplasty : Disappointing medium and long terms results.

The TRAC prosthesis is a dual radius, mobile bearing, posterior stabilized prosthesis, to increase stability by optimizing contact area and control wear using a mobile polyethylene. Between February 1995 and January 2000, a single surgeon performed a continuous series of 85 TRAC-PS TKAs in 85 patients at the University Hospital Brussels. A retrospective review on patient charts was performed. Patients available were scored clinically using the Knee Society Score, WOMAC osteoarthritis index, SF 36 and a Visual Analogue Scale for pain. 43 patients had died at time of evaluation, three were unavailable for examination due to bad general health and five were lost to follow up. The remaining 35 patients were examined with a mean follow-up of 13 years. The mean age of the patients at follow up was 83 years. The mean WOMAC score was 78,4(SD 17,9). The mean Knee Society Score was 86.8(SD 8,4) clinical and 42,6(SD 28) functional. The mean range of flexion was 105°. The mean SF-36 score was 59,8(SD 15,4). The VAS for pain was 6(SD 9). With revision (8 cases) as endpoint, survival rate of the prosthesis was estimated to be 92% at 13 years. Twenty-three Serious Adverse Events (28%) in 17 patients, related to the prosthesis were registered in this patient group. Long term results of this prosthesis were satisfying but a large number of serious adverse events led to abandonment of the TRAC-prosthesis.

Development and validation of an automated and marker-free CT-based spatial analysis method (CTSA) for assessment of femoral hip implant migration: In vitro accuracy and precision comparable to that of radiostereometric analysis (RSA).

BACKGROUND AND PURPOSE: We developed a marker-free automated CT-based spatial analysis (CTSA) method to detect stem-bone migration in consecutive CT datasets and assessed the accuracy and precision in vitro. Our aim was to demonstrate that in vitro accuracy and precision of CTSA is comparable to that of radiostereometric analysis (RSA). MATERIAL AND METHODS: Stem and bone were segmented in 2 CT datasets and both were registered pairwise. The resulting rigid transformations were compared and transferred to an anatomically sound coordinate system, taking the stem as reference. This resulted in 3 translation parameters and 3 rotation parameters describing the relative amount of stem-bone displacement, and it allowed calculation of the point of maximal stem migration. Accuracy was evaluated in 39 comparisons by imposing known stem migration on a stem-bone model. Precision was estimated in 20 comparisons based on a zero-migration model, and in 5 patients without stem loosening. RESULTS: Limits of the 95% tolerance intervals (TIs) for accuracy did not exceed 0.28 mm for translations and 0.20° for rotations (largest standard deviation of the signed error (SD(SE)): 0.081 mm and 0.057°). In vitro, limits of the 95% TI for precision in a clinically relevant setting (8 comparisons) were below 0.09 mm and 0.14° (largest SD(SE): 0.012 mm and 0.020°). In patients, the precision was lower, but acceptable, and dependent on CT scan resolution. INTERPRETATION: CTSA allows detection of stem-bone migration with an accuracy and precision comparable to that of RSA. It could be valuable for evaluation of subtle stem loosening in clinical practice.

Advanced imaging of the scapholunate ligamentous complex.

The scapholunate joint is one of the most involved in wrist injuries. Its stability depends on primary and secondary stabilisers forming together the scapholunate complex. This ligamentous complex is often evaluated by wrist arthroscopy. To avoid surgery as diagnostic procedure, optimization of MR imaging parameters as use of three-dimensional (3D) sequences with very thin slices and high spatial resolution, is needed to detect lesions of the intrinsic and extrinsic ligaments of the scapholunate complex. The paper reviews the literature on imaging of radial-sided carpal ligaments with advanced computed tomographic arthrography (CTA) and magnetic resonance arthrography (MRA) to evaluate the scapholunate complex. Anatomy and pathology of the ligamentous complex are described and illustrated with CTA, MRA and corresponding arthroscopy. Sprains, mid-substance tears, avulsions and fibrous infiltrations of carpal ligaments could be identified on CTA and MRA images using 3D fat-saturated PD and 3D DESS (dual echo with steady-state precession) sequences with 0.5-mm-thick slices. Imaging signs of scapholunate complex pathology include: discontinuity, nonvisualization, changes in signal intensity, contrast extravasation (MRA), contour irregularity and waviness and periligamentous infiltration by edema, granulation tissue or fibrosis. Based on this preliminary experience, we believe that 3 T MRA using 3D sequences with 0.5-mm-thick slices and multiplanar reconstructions is capable to evaluate the scapholunate complex and could help to reduce the number of diagnostic arthroscopies.

Discussing sexual health with patients eligible for spine surgery: An online survey in spine surgeon and pain physicians.

Introduction: Spinal pain syndromes have a severe impact on the patient's sex life, contributing to a decrease in sexual function and sexual satisfaction. Despite the importance of sexual health on mental and physical wellbeing, sexual health is rarely discussed during consultations. Research question: The aim of this study is to explore to what extent influencing factors can alter the discussion about sexual health during consultations. More specifically, we will evaluate the influence of healthcare profession, sex of the patient and the surgical approach that is proposed. Material and methods: An online survey was sent to neurosurgeons, pain physicians and orthopedists in Belgium and The Netherlands in April 2019. Participants were asked about; counseling routine, knowledge, and opinion on sexual health. Answers were scored on a 5-point Likert scale. Independence between the response levels and type of surgery as well as profession were tested. Results: In total, 350 respondents were approached of whom 57 completed the survey. The majority of respondents (61.4%) indicated that they rarely or never discussed sexual disturbances. Profession and type of surgery had an influence on discussing erectile dysfunction, retrograde ejaculation, and alterations in orgasms. Thirty-five percent of healthcare providers considered it the patient's responsibility to bring up the subject of sexual health. Discussion and conclusion: Sexual health is rarely addressed by healthcare providers during spinal care. Profession as well as type of surgery seems to play a role on whether sexual health is discussed during consultations.

Determination of rotation center and diameter of femoral heads using off-the-shelf augmented reality hardware for navigation.

In total hip arthroplasty (THA), determining the center of rotation (COR) and diameter of the hip joint (acetabulum and femoral head) is essential to restore patient biomechanics. This study investigates on-the-fly determination of hip COR and size, using off-the-shelf augmented reality (AR) hardware. An AR head-mounted device (HMD) was configured with inside-out infrared tracking enabling the determination of surface coordinates using a handheld stylus. Two investigators examined 10 prosthetic femoral heads and cups, and 10 human femurs. The HMD calculated the diameter and COR through sphere fitting. Results were compared to data obtained from either verified prosthetic geometry or post-hoc CT analysis. Repeated single-observer measurements showed a mean diameter error of 0.63 mm ± 0.48 mm for the prosthetic heads and 0.54 mm ± 0.39 mm for the cups. Inter-observer comparison yielded mean diameter errors of 0.28 mm ± 0.71 mm and 1.82 mm ± 1.42 mm for the heads and cups, respectively. Cadaver testing found a mean COR error of 3.09 mm ± 1.18 mm and a diameter error of 1.10 mm ± 0.90 mm. Intra- and inter-observer reliability averaged below 2 mm. AR-based surface mapping using HMD proved accurate and reliable in determining the diameter of THA components with promise in identifying COR and diameter of osteoarthritic femoral heads.

Automated analysis of trapeziometacarpal joint kinematics using four-dimensional computed tomography.

The aim of this study was to develop an automated approach model to define in vivo kinematics of the trapeziometacarpal (TMC) joint using four-dimensional computed tomography. A total of 15 healthy volunteers were included and their TMC joint kinematics were studied during a retropulsion-opposition-retropulsion movement. We used cardan angles estimated from transformation matrices using a ZYX-decomposition and analysed the motion of the thumb metacarpal relative to the trapezium, the thumb metacarpal relative to the index metacarpal, and the trapezium relative to the index metacarpal. The study also included an analysis of the joint hysteresis effect and a joint proximity model that estimated the joint contact area during a retropulsion-opposition-retropulsion movement. The automated approach significantly decreased the time needed to analyse each case and makes this model applicable for further research on TMC kinematics.

Addition-subtraction osteotomy without ligamentoplasty for symptomatic trapezial dysplasia with metacarpal instability.

Trapeziometacarpal joint pain is often associated with a dynamic adduction deformity of the thumb metacarpal, combined with radial subluxation at the base of the thumb metacarpal, due to trapeziometacarpal dysplasia. Addition-subtraction osteotomy is a surgical option to correct the bony deformity when conservative treatment fails. Eight patients who underwent surgery with this technique were prospectively evaluated. All patients were female and mean age was 42 (range 27-59) years. Mean follow-up period was 23 (range 10-42) months postoperatively. Seven patients (87.5%) were very satisfied. Joint mobility and strength of the operated thumb was restored to a degree comparable to the contralateral thumb. Overall function according to the Quick-DASH score improved by 75.5% and pain according to the Visual Analogue Scale decreased by 65%. Radiological evaluation showed a decrease of the trapezial slope. Mean angle between the articular surface of the trapezium and the long axis of the second metacarpal measured 1420 preoperatively 1290 and postoperatively. In the present study results of addition-subtraction osteotomy without ligamentoplasty were promising, especially for function and pain. The technique may be a valuable treatment option for trapeziometacarpal dysplasia with metacarpal instability.

Neuro-oncological augmented reality planning for intracranial tumor resection.

Background: Before starting surgery for the resection of an intracranial tumor, its outlines are typically marked on the skin of the patient. This allows for the planning of the optimal skin incision, craniotomy, and angle of approach. Conventionally, the surgeon determines tumor borders using neuronavigation with a tracked pointer. However, interpretation errors can lead to important deviations, especially for deep-seated tumors, potentially resulting in a suboptimal approach with incomplete exposure. Augmented reality (AR) allows displaying of the tumor and critical structures directly on the patient, which can simplify and improve surgical preparation. Methods: We developed an AR-based workflow for intracranial tumor resection planning deployed on the Microsoft HoloLens II, which exploits the built-in infrared-camera for tracking the patient. We initially performed a phantom study to assess the accuracy of the registration and tracking. Following this, we evaluated the AR-based planning step in a prospective clinical study for patients undergoing resection of a brain tumor. This planning step was performed by 12 surgeons and trainees with varying degrees of experience. After patient registration, tumor outlines were marked on the patient's skin by different investigators, consecutively using a conventional neuronavigation system and an AR-based system. Their performance in both registration and delineation was measured in terms of accuracy and duration and compared. Results: During phantom testing, registration errors remained below 2.0 mm and 2.0° for both AR-based navigation and conventional neuronavigation, with no significant difference between both systems. In the prospective clinical trial, 20 patients underwent tumor resection planning. Registration accuracy was independent of user experience for both AR-based navigation and the commercial neuronavigation system. AR-guided tumor delineation was deemed superior in 65% of cases, equally good in 30% of cases, and inferior in 5% of cases when compared to the conventional navigation system. The overall planning time (AR = 119 ± 44 s, conventional = 187 ± 56 s) was significantly reduced through the adoption of the AR workflow (p < 0.001), with an average time reduction of 39%. Conclusion: By providing a more intuitive visualization of relevant data to the surgeon, AR navigation provides an accurate method for tumor resection planning that is quicker and more intuitive than conventional neuronavigation. Further research should focus on intraoperative implementations.

Exploring technology acceptance of head-mounted device-based augmented reality surgical navigation in orthopaedic surgery.

BACKGROUND: This study used the Unified Theory of Acceptance and Use of Technology (UTAUT) to investigate the acceptance of HMD-based AR surgical navigation. METHODS: An experiment was conducted in which participants drilled 12 predefined holes using freehand drilling, proprioceptive control, and AR assistance. Technology acceptance was assessed through a survey and non-participant observations. RESULTS: Participants' intention to use AR correlated (p < 0.05) with social influence (Spearman's rho (rs) = 0.599), perceived performance improvement (rs = 0.592) and attitude towards AR (rs = 0.542). CONCLUSIONS: While most participants acknowledged the potential of AR, they also highlighted persistent barriers to adoption, such as issues related to user-friendliness, time efficiency and device discomfort. To overcome these challenges, future AR surgical navigation systems should focus on enhancing surgical performance while minimising disruptions to workflows and operating times. Engaging orthopaedic surgeons in the development process can facilitate the creation of tailored solutions and accelerate adoption.

Dynamic CT scanning of the knee: Combining weight bearing with real-time motion acquisition.

BACKGROUND: Imaging the lower limb during weight-bearing conditions is essential to acquire advanced functional joint information. The horizontal bed position of CT systems however hinders this process. The purpose of this study was to validate and test a device to simulate realistic knee weight-bearing motion in a horizontal position during dynamic CT acquisition and process the acquired images. METHODS: "Orthostatic squats" was compared to "Horizontal squats" on a device with loads between 35% and 55% of the body weight (%BW) in 20 healthy volunteers. Intraclass Correlation Coefficient (ICC), and standard error of measurement (SEM), were computed as measures of the reliability of curve kinematic and surface EMG (sEMG) data. Afterwards, the device was tested during dynamic CT acquisitions on three healthy volunteers and three patients with patellofemoral pain syndrome. The respective images were processed to extract Tibial-Tuberosity Trochlear-Groove distance, Bisect Offset and Lateral Patellar Tilt metrics. RESULTS: For sEMG, the highest average ICCs (SEM) of 0.80 (6.9), was found for the load corresponding to 42%BW. Kinematic analysis showed ICCs were the highest for loads of 42%BW during the eccentric phase (0.79-0.87) and from maximum flexion back to 20° (0.76). The device proved to be safe and reliable during the acquisition of dynamic CT images and the three metrics were computed, showing preliminary differences between healthy and pathological participants. CONCLUSIONS: This device could simulate orthostatic squats in a horizontal position with good reliability. It also successfully provided dynamic CT scan images and kinematic parameters of healthy and pathological knees during weight-bearing movement.

Defining trapezial dysplasia - analysis of trapezial inclination in a normal population.

We assess the distribution of trapezial inclination in a young population in order to propose a threshold for trapezial dysplasia. One hundred peritrapezial views were reconstructed from wrist computed tomography scan datasets to measure trapezial inclination. Seventy peritrapezial views were constructed from 10 datasets to assess the influence of radiograph rotation. Mean trapezial inclination in our population was 8° (range 0.2-17.9). Fifteen degrees of radiographic pronation or supination did not alter trapezial inclination significantly. Intra-rater consistency and absolute agreement had an interclass correlation (ICC) of 0.95. Inter-rater consistency and absolute agreement had an ICC of 0.88. Trapezial inclination is a reliable measurement for trapezial dysplasia with an excellent intra-rater and good inter-rater reliability and does not change significantly with 15° of radiographic pronation or supination. These normal values can be used to propose a threshold for trapezial dysplasia in the management of trapeziometacarpal joint instability in the younger population.Level of evidence: IV.

The use of cardiac CT acquisition mode for dynamic musculoskeletal imaging.

OBJECTIVES: To quantitatively evaluate the impact of a cardiac acquisition CT mode on motion artifacts in comparison to a conventional cine mode for dynamic musculoskeletal (MSK) imaging. METHODS: A rotating PMMA phantom with air-filled holes drilled at varying distances from the disk center corresponding to linear hole speeds of 0.75 cm/s, 2.0 cm/s, and 3.6 cm/s was designed. Dynamic scans were obtained in cardiac and cine modes while the phantom was rotating at 48°/s in the CT scanner. An automated workflow to compute the Jaccard distance (JD) was established to quantify degree of motion artifacts in the reconstructed phantom images. JD values between the cardiac and cine scan modes were compared using a paired sample t-test. In addition, three healthy volunteers were scanned with both modes during a cyclic flexion-extension motion of the knee and analysed using the proposed metric. RESULTS: For all hole sizes and speeds, the cardiac scan mode had significantly lower (p-value <0.001) JD values. (0.39 [0.32-0.46]) i.e less motion artifacts in comparison to the cine mode (0.72 [0.68-0.76]). For both modes, a progressive increase in JD was also observed as the linear speed of the holes increased from 0.75 cm/s to 3.6 cm/s. The dynamic images of the three healthy volunteers showed less artifacts when scanned in cardiac mode compared to cine mode, and this was quantitatively confirmed by the JD values. CONCLUSIONS: A cardiac scan mode could be used to study dynamic musculoskeletal phenomena especially of fast-moving joints since it significantly minimized motion artifacts.

Hip implants can restore anatomical and medialized rotation centres in most cases : a 3D templating study comparing four implantation strategies.

AIMS: Hip arthroplasty does not always restore normal anatomy. This is due to inaccurate surgery or lack of stem sizes. We evaluated the aptitude of four total hip arthroplasty systems to restore an anatomical and medialized hip rotation centre. METHODS: Using 3D templating software in 49 CT scans of non-deformed femora, we virtually implanted: 1) small uncemented calcar-guided stems with two offset options (Optimys, Mathys), 2) uncemented straight stems with two offset options (Summit, DePuy Synthes), 3) cemented undersized stems (Exeter philosophy) with three offset options (CPT, ZimmerBiomet), and 4) cemented line-to-line stems (Kerboul philosophy) with proportional offsets (Centris, Mathys). We measured the distance between the templated and the anatomical and 5 mm medialized hip rotation centre. RESULTS: Both rotation centres could be restored within 5 mm in 94% and 92% of cases, respectively. The cemented undersized stem performed best, combining freedom of stem positioning and a large offset range. The uncemented straight stem performed well because of its large and well-chosen offset range, and despite the need for cortical bone contact limiting stem positioning. The cemented line-to-line stem performed less well due to a small range of sizes and offsets. The uncemented calcar-guided stem performed worst, despite 24 sizes and a large and well-chosen offset range. This was attributed to the calcar curvature restricting the stem insertion depth along the femoral axis. CONCLUSION: In the majority of non-deformed femora, leg length, offset, and anteversion can be restored accurately with non-modular stems during 3D templating. Failure to restore hip biomechanics is mostly due to surgical inaccuracy. Small calcar guided stems offer no advantage to restore hip biomechanics compared to more traditional designs. Cite this article: Bone Jt Open 2021;2(7):476-485.

Cemented short-stem total hip arthroplasty: Characteristics of line-to-line versus undersized cementing techniques using a validated CT-based finite element analysis.

Short stems are becoming increasingly popular in total hip arthroplasty as they preserve the bone stock and simplify the implantation process. Short stems are advised mainly for patients with good bone stock. The clinical use of short stems could be enlarged to patients with poor bone stock if a cemented alternative would be available. Therefore, this study aimed to quantify the mechanical performance of a cemented short stem and to compare the "undersized" cementing strategy (stem one size smaller than the rasp) with the "line-to-line" technique (stem and rasp with identical size). A prototype cemented short stem was implanted in eight pairs of human cadaveric femora using the two cementing strategies. Four pairs were experimentally tested in a single-legged stance condition; stiffness, strength, and bone surface displacements were measured. Subject-specific nonlinear finite element models of all the implanted femora were developed, validated against the experimental data, and used to evaluate the behavior of cemented short stems under physiological loading conditions resembling level walking. The two cementing techniques resulted in nonsignificant differences in stiffness and strength. Strength and stiffness as calculated from finite element were 8.7 ± 16% and 9.9 ± 15.0% higher than experimentally measured. Displacements as calculated from finite element analyses corresponded strongly (R 2 ≥ .97) with those measured by digital image correlation. Stresses during level walking were far below the fatigue limit for bone and bone cement. The present study suggests that cemented short stems are a promising solution in osteoporotic bone, and that the line-to-line and undersized cementing techniques provide similar outcomes.