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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.

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

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

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.

Evaluating musculoskeletal conditions of the lower limb and understanding the pathophysiology of complex bone kinematics is challenging. Static images do not take into account the dynamic component of relative bone motion and muscle activation. Fluoroscopy and dynamic MRI have important limitations. Dynamic CT (4D-CT) is an emerging alternative that combines high spatial and temporal resolution, with an increased availability in clinical practice. 4D-CT allows simultaneous visualization of bone morphology and joint kinematics. This unique combination makes it an ideal tool to evaluate functional disorders of the musculoskeletal system. In the lower limb, 4D-CT has been used to diagnose femoroacetabular impingement, patellofemoral, ankle and subtalar joint instability, or reduced range of motion. 4D-CT has also been used to demonstrate the effect of surgery, mainly on patellar instability. 4D-CT will need further research and validation before it can be widely used in clinical practice. We believe, however, it is here to stay, and will become a reference in the diagnosis of lower limb conditions and the evaluation of treatment options. Cite this article: Bone Joint J 2021;103-B(5):822–827.

Trapeziometacarpal instability is a well-known condition that could lead to trapeziometacarpal osteoarthritis. With the focus in the literature being on ligament insufficiency, bony deformity has received much less attention. Although trapezial tilt is currently used to measure trapezial dysplasia, we believe trapezial inclination is a more reliable measurement. The purpose of this study is to compare these two methods for evaluating trapezial dysplasia and to define the most reproducible measurement. Fifty patients were identified who had three consecutive radiographs of the trapeziometacarpal joint. Eaton views with little to no signs of osteoarthritis (Eaton stage I or II) were used. Both trapezial tilt and trapezial inclination were measured by two independent observers on three radiographs for every patient. Intra-observer variation, absolute agreement and consistency, and intra-observer variation and consistency were assessed for both measurements. Mean trapezial tilt was 135° and mean trapezial inclination was 10°. For both observers, intra-observer variation of trapezial inclination was significantly less than for trapezial tilt. Our study shows that mean trapezial inclination in a middle-aged adult population is approximately 10°. This measurement is more reproducible than the more frequently used trapezial tilt and may be a better parameter to define trapezial dysplasia and to guide its treatment.

BACKGROUND When preparing for the resection of an intracranial lesion, its borders and optimal approach are often determined using neuronavigation with a tracked pointer. This can sometimes prove challenging, especially for deep-seated lesions. Augmented reality (AR) can simplify and improve this step by directly displaying the lesion on the patient's skin. METHODS A proprietary inside-out infrared tracking solution was developed, allowing for heads-up displaying AR scenes on the Microsoft HoloLens II without the need for an external tracking camera or computer. We included twenty patients with an intracerebral lesion planned for resection. After semi-automatic hologram-to-patient registration, different participants marked the lesion outlines on the patient’s skin, consecutively aided by the Brainlab neuronavigation system and the HoloLens. Each registration on both systems provided a registration transform that was compared for accuracy and consistency. Participant performance was quantified in terms of duration and accuracy for both patient registration and lesion delineation, and compared to expert performance. RESULTS When using AR both registration and delineation were significantly faster than with conventional neuronavigation (p = 0.02 and p < 0.001, respectively, and p < 0.001 for the total duration), taking 79.23 ± 17.48 and 39.58 ± 39.10 seconds while neuronavigation required 96.61 ± 24.54 and 90.80 ± 44.09 seconds. AR had a registration offset of 3.3mm and 3.4°, and was more consistent compared to neuronavigation. AR facilitated more accurate and detailed lesion delineation, while neuronavigation often overestimated lesion size. CONCLUSION Augmented reality provides a faster and more accurate alternative for resection planning. Lesion delineation was more intuitive while retaining high accuracy. Future research should focus on further intraoperative implementations.

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. ispartof: JOURNAL OF ORTHOPAEDIC RESEARCH vol:39 issue:8 pages:1681-1690 ispartof: location:United States status: published

Summary: This study analyzed characteristics of hip fracture patients who did not undergo surgery within 24 hours after hospitalization, as recommended by the Belgian quality standards. Reasons for delay were analyzed. Delay in surgery for hip fracture was related to the medical condition of the patients. Introduction: To compare patients with optimal timing to patients with a delay in hip surgery, with respect to outcome (complications (postoperative) and mortality) and reasons for delay. Methods: A retrospective analysis of medical records compared patients operated on within 24h (Group A) to patients operated on more than 24h after admission (Group B). A follow-up period of 5 years after release or up to the time of data collection was used. Reasons for delay in relation with mortality were analyzed descriptively. Descriptive statistics were used for patient demographics and complications. Relationships causing a delayed surgery and mortality were analyzed using binary logistic regression. Additionally, a survival analysis was provided for overall mortality. Results: Respectively, 536 and 304 patients were included in Group A and B. The most prominent reason for delaying surgery was the patient not being medically fit (20.7%). Surgical delay was associated with more cardiovascular (p = 0.010), more pulmonary (p < 0.001), and less hematologic complications (p=0.037). Thirty-day mortality was higher with increasing age (p < 0.001), with hematologic (p < 0.001) or endocrine-metabolic complications (p = 0.001), and lower when no complications occurred (p = 0.004). Mortality at the end of data collection was higher for patients with delayed surgery (OR = 2.634, p < 0.001), an increased age (p = 0.006), male gender (p < 0.001), institutionalized patients (p = 0.009), pulmonary complication (p = 0.002), and having no endocrine-metabolic complications (p = 0.003). Survival analysis showed better survival for patients operated on within 24h (p < 0.001). Conclusions: Delayed surgery for patients with hip fractures was associated with bad additional medical conditions. Survival was higher for patients operated on within 24h of admission.

Dynamic computer tomography (CT) is an emerging modality to analyze in-vivo joint kinematics at the bone level, but it requires manual bone segmentation and, in some instances, landmark identification. The objective of this study is to present an automated workflow for the assessment of three-dimensional in vivo joint kinematics from dynamic musculoskeletal CT images. The proposed method relies on a multi-atlas, multi-label segmentation and landmark propagation framework to extract bony structures and detect anatomical landmarks on the CT dataset. The segmented structures serve as regions of interest for the subsequent motion estimation across the dynamic sequence. The landmarks are propagated across the dynamic sequence for the construction of bone embedded reference frames from which kinematic parameters are estimated. We applied our workflow on dynamic CT images obtained from 15 healthy subjects on two different joints: thumb base (n = 5) and knee (n = 10). The proposed method resulted in segmentation accuracies of 0.90 ± 0.01 for the thumb dataset and 0.94 ± 0.02 for the knee as measured by the Dice score coefficient. In terms of motion estimation, mean differences in cardan angles between the automated algorithm and manual segmentation, and landmark identification performed by an expert were below 1°. Intraclass correlation (ICC) between cardan angles from the algorithm and results from expert manual landmarks ranged from 0.72 to 0.99 for all joints across all axes. The proposed automated method resulted in reproducible and reliable measurements, enabling the assessment of joint kinematics using 4DCT in clinical routine.

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.

The objective of the current study was to explore the potential of dynamic computed tomography to detect kinematic changes, induced by sequential sectioning of the lateral collateral ligaments of the ankle, during full motion sequence of the talocrural joint. A custom-made device was used to induce cyclic controlled ankle inversion movement in one fresh frozen cadaver leg. A 256-slice CT scanner was used to investigate four different scenarios. Scenario 1 with all ligaments intact was first investigated followed by sequential section of the anterior talo-fibular ligament (Scenario 2), the calcaneo-fibular ligament (Scenario 3) and posterior talo-fibular ligament (Scenario 4). Off-line image processing based on semi-automatic segmentation and bone rigid registration was performed. Motion parameters such as translation, rotational angles and orientation and position of the axis of rotation were calculated. Differences between scenarios were calculated. Progressive increase of cranio-caudal displacement up to 3.9 mm and flexion up to 10° compared to Scenario 1 were reported. Progressive changes in orientation (up to 20.6°) and position (up to 4.1 mm) of the axis of rotation were also shown. Estimated effective dose of 0.005 mSv (1.9 mGy CTDIvol) was reported. This study demonstrated that kinematic changes due to the absence of ligament integrity can be detected with 4DCT with minimal radiation exposure. Identifying abnormal kinematic patterns could have future application in helping clinicians to choose patients’ optimal treatment. Therefore, further studies with bigger in vitro sample sizes and consequent investigations in vivo are recommended to confirm the current findings.

Evaluating musculoskeletal conditions of the lower limb and understanding the pathophysiology of complex bone kinematics is challenging. Static images do not take into account the dynamic component of relative bone motion and muscle activation. Fluoroscopy and dynamic MRI have important limitations. Dynamic CT (4D-CT) is an emerging alternative that combines high spatial and temporal resolution, with an increased availability in clinical practice. 4D-CT allows simultaneous visualization of bone morphology and joint kinematics. This unique combination makes it an ideal tool to evaluate functional disorders of the musculoskeletal system. In the lower limb, 4D-CT has been used to diagnose femoroacetabular impingement, patellofemoral, ankle and subtalar joint instability, or reduced range of motion. 4D-CT has also been used to demonstrate the effect of surgery, mainly on patellar instability. 4D-CT will need further research and validation before it can be widely used in clinical practice. We believe, however, it is here to stay, and will become a reference in the diagnosis of lower limb conditions and the evaluation of treatment options. Cite this article

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) (P0.001). 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.

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.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.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.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.

Background There is no consensus regarding superiority between gap balancing (GB) and measured resection (MR) techniques to implant total knee arthroplasties. In a multicenter setup, we compared both techniques using the same prosthesis. Methods We included 262 balanSys posterior-stabilized total knee arthroplasties from 4 centers: 3 using the MR (n = 162) and one using the GB technique (n = 100), without navigation. Results There was no significant difference in the Knee Society Score or visual analog scale pain at 2- and 7-year follow-up. The visual analog scale for satisfaction was significantly better in the MR group at 2 but not at 7 years. We found a significantly higher average valgus in the GB group, but the overall alignment was within 2° of neutral on the full-leg radiographs. There were no significant differences concerning radiolucency and survival. Conclusions We found no significant differences in the functional outcome, pain, alignment, or survival, but a tendency toward better function using MR and better survival with GB.

Flexor tendon injury after volar plating of distal radius fractures is due to friction against the plate. To assess this risk, the distance between the flexor pollicis longus (FPL) and the volar prominence of the plate was measured with ultrasonography under various conditions: a standard plate fixed proximal or distal to the watershed line and a low-profile volar rim plate, with and without transection of the pronator quadratus (PQ). Distance from the FPL to the volar prominence of the plate decreased significantly when the PQ was cut and when a standard plate was placed distal to the watershed line, with the tendon often bulging over the plate. No statistical difference was measured between a volar rim plate and a standard plate distal to the watershed line. Our results confirm the importance of positioning the volar plate proximal to the watershed line and of repairing the PQ.

Introduction: We investigated the in vivo gentamicin elution kinetics of Hi-Fatigue Gentamicin Bone Cement (AAP Biomaterials GmbH) in serum and drain fluid after hybrid hip arthroplasty and the relationship with cement mantle thickness. Methods: We compared in a randomised, non-blinded prospective study, the local and systemic gentamicin concentrations in 2 groups. The thin cement mantle group ( n = 16) received a stem implanted line-to-line with the broach, whereas the thick group ( n = 14) had an undersized stem. Gentamicin concentrations were measured in drain fluid and serum at set intervals for 3 days postoperatively. Results: In both groups, local gentamicin concentrations were similar. After a high initial burst above the minimal inhibitory concentration (thin: 57.2 mg/L (SD 34.4), thick: 54.9 mg/L (SD 19.9), p = 0.823) local gentamicin concentrations declined rapidly. In both groups, serum concentrations never exceeded toxic levels (maximum 1.08 mg/L). Conclusion: In hybrid total hip arthroplasty, Hi-Fatigue Gentamicin Bone Cement resulted in effective and safe gentamicin concentrations. Clinical trial protocol number: PMCI 12/02.

Short stem hip implants are becoming increasingly popular since they preserve bone stock and presumably reduce stress-shielding. However, concerns remain whether they are suitable for a wide range of patients with varying anatomy. The aim of this study was to investigate how femoral anatomy influences stress-shielding induced by a short calcar-guided stem across a set of 90 CT-based femur models. A computational tool was developed that automatically selected the optimal size and position of the stem. Finite element models of the intact and implanted femurs were constructed and subjected to walking loads. Stress-shielding was evaluated in relevant volumes of interest of the proximal femur. After a detailed anatomical analysis, linear regression was performed to find potential correlations between anatomy and stress-shielding. Stress-shielding was found to be highest in the proximal regions on the medial and posterior side. A highly significant negative relationship was observed between stress-shielding and bone density; a strong positive relationship was observed with stem size and the valgus orientation of the stem with respect to the femur. The results reveal how anatomy influences stress-shielding, and they highlight the importance of evaluating new implant designs across a large population taking into account the anatomical variability. The study demonstrates that such large population studies can be conducted in an efficient way using an automated workflow. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:1-8, 2019. ispartof: JOURNAL OF ORTHOPAEDIC RESEARCH vol:37 issue:3 pages:681-688 ispartof: location:United States status: published

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 (SDSE): 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 SDSE: 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.

Transcutaneous electric nerve stimulation (TENS) has proven to be effective for postsurgical pain relief. However, there is a lack of well-constructed clinical trials investigating the effect of TENS after total knee arthroplasty (TKA). In addition, previous investigations reported that low- and high-frequency TENSs produced analgesic tolerance after 4 or 5 days of treatment. The aim of this study is to explore the effect of burst TENS on pain during hospitalization after TKA and to investigate whether burst TENS produces analgesic tolerance after 4 or 5 days of treatment. This stratified, triple blind, randomized controlled trial was approved by the University Hospital Brussels. Sixty-eight subjects were screened for eligibility before surgery; 54 were found eligible and 53 were included in the analyses. Patients were allocated to either a burst TENS or sham burst TENS group. TENS was applied daily during continuous passive mobilization. Knee pain intensity, knee range of motion, and analgesic consumption were assessed daily. Patients received burst TENS (N = 25) or sham burst TENS (N = 28). No significant differences in knee pain intensity were found between the groups (p > 0.05). Within the TENS and the sham TENS groups, the difference in knee pain before and after treatment did not evolve over time (p > 0.05). This study found no effects of burst TENS compared with sham burst TENS on pain during hospitalization after TKA.

Background: Specific treatment of the volar marginal rim fragment of distal radius fractures avoids occurance of volar radiocarpal dislocation. Although several fixation systems are available to capture this fragment, adequately maintaining internal fixation is difficult. We present our experience of the first 10 cases using the 2.4 mm variable angle LCP volar rim distal radius plate (Depuy Synthes®, West Chester, US), a low-profile volar rim-contouring plate designed for distal plate positioning and stable buttressing of the volar marginal fragment. Methods: Follow-up patient satisfaction, range of motion, grips strength, functional scoring with the QuickDASH and residual pain with a numeric rating scale were assessed. Radiological evaluation consisted in evaluating fracture consolidation, ulnar variance, volar angulation and maintenance of the volar rim fixation. Results: The female to male ratio was 5:5 and the mean age was 52.2 (range, 17–80) years. The mean follow-up period was 11 (range, 5–19) months postoperatively. Patient satisfaction was high. The mean total flexion/extension range was 144° (range, 100–180°) compared to the contralateral uninjured side 160° (range, 95–180°). The mean total pronation/supination range was 153° (range, 140–180°) compared to the contralateral uninjured side 170° (range, 155–180°). Mean grip strength was 14 kg (range, 9–22), compared to the contralateral uninjured side 20 kg (range, 12–25 kg). Mean pre-injury level activity QuickDASH was 23 (range, 0–34.1), while post-recovery QuickDASH was 25 (range 0–43.2). Residual pain was 1.5 on the visual numerical pain rating scale. Radiological evaluation revealed in all cases fracture consolidation, satisfactory reconstruction of ulnar variance, volar angulation and volar rim. We encountered no flexor tendon complications, although plate removal was systematically performed after fracture consolidation. Conclusions: The 2.4 mm variable angle LCP volar rim distal radius plates is a valid treatment option for treating the volar marginal fragment in distal radius fractures.

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.

Introduction Natural population variation in femoral morphology results in a large range of offsets, anteversion angles and lengths. During total hip arthroplasty, accurate restoration of hip biomechanics is essential to achieve good functional results. One option is to restore the anatomic hip rotation center. Alternatively, medializing the rotation center and compensating by increasing the femoral offset, reduces acetabular contact forces and increases the abductor lever arm. We investigated the ability of two cemented stem systems to restore hip biomechanics in an anatomic and medialized way. We compared an undersized “Exeter-type” of stem with three offset options and 18 sizes (CPT, Zimmer), to a line-to-line “Kerboul-type” of stem with proportional offset and 12 sizes (Centris, Mathys). Methods Thirty CT scans of whole femora were segmented and the hip rotation center, proximal femoral axis and femoral length were determined with Mimics and 3-matic (Materialise). Using scripting functionality in the software, CAD design files of both stems were automatically sized and aligned along the proximal femoral axis to restore an anatomical and a 5 mm medialized hip rotation center. Stem size and position could be fine-tuned manually. The maximum distances between the prosthetic (PRC), the anatomic (ARC) and the medialized hip rotation center (MRC) were calculated (Fig. 1). Variations in femoral offset (ΔFO), anteroposterior (ΔAP) and proximodistal distance (ΔPD) were analyzed. Finally, the number of cases where the hip rotation center could be restored within 5 mm was reported. Results Both implants allowed restoring the ARC accurately (mean distance PRC-ARC: CPT 0.97±0.88 mm, Centris 1.66±1.59 mm; mean difference ΔFO: CPT 0.09±0.19 mm, Centris 0.11±0.29 mm; mean difference ΔAP: CPT 0.12±1.22°, Centris 0.27±1.78 mm, mean difference ΔPD: CPT 0.04±0.44 mm, Centris 0.49±1.35 mm). The CPT stem allowed restoring the PRC within 5 mm of the ARC in all cases (max. 4.31 mm), whereas the Centris stem achieved this in only 28/30 hips (max. 6.72 mm) (Fig. 2). Aiming for a MRC was less satisfactory with both stems (mean distance PRC-MRC: CPT 1.38±1.63 mm, Centris 3.61±2.73 mm; mean difference ΔFO: CPT 0.09±0.10 mm, Centris 0.06±0.35 mm; mean difference ΔAP: CPT 0.17±2.02 mm, Centris 2.58±2.68 mm, mean difference ΔDP; CPT 0.28±0.67 mm, Centris 1.98±1.66 mm). The CPT stem allowed restoring the PRC within 5 mm of the MRC in 29/30 cases (max. 8.09 mm), whereas the Centris stem achieved this in only 25/30 cases (max. 11.15 mm) (Fig. 3). Discussion Although both stem systems allowed restoring hip biomechanics accurately in most cases, the CPT system was superior to the Centris stem for achieving both ARC and MRC. This could be explained by more implant sizes (18 vs. 12) and undersized stems offering more freedom to correct version. Although medializing the hip rotation center offers biomechanical advantages, both stems had more difficulties achieving this. In some cases, differences between aimed and planned rotation centers were close to 1 cm which might negatively impact on clinical outcome. As such, to avoid suboptimal reconstructions with the available implants, templating is mandatory especially when aiming at a medialized reconstruction strategy.

PURPOSE: Exercise is effective for reducing knee osteoarthritis (OA) pain but effect sizes vary widely. Moreover, not all knee OA patients perceive beneficial effects. Tailoring specific exercises to subgroups of knee OA patients may increase effectivity. Bone marrow lesions (BMLs) have been suggested as a criterion to define such subgroups. This study aimed to investigate whether BMLs' presence/absence is related to treatment outcomes in a group of knee OA patients who exercised for 18 weeks. METHODS: Subjects with symptomatic knee OA started a strength or walking exercise program. BMLs' presence at baseline was assessed. Pain was assessed before and after the intervention with the intermittent and constant osteoarthritis pain (ICOAP) questionnaire. Also the global perceived effect (GPE) on the patient's complaints was rated. RESULTS: Thirty-five patients (strength (N = 17) and walking (N = 18)) were analyzed for BMLs. BMLs were present in 25 (71%) knees. Five (14%) patients dropped out and 19 (54%) improved (GPE ≥5). All dropouts had BMLs, but no difference was seen between dropouts and retainers (p > 0.05). Pain scores did not differ between intervention groups (p > 0.05) or between patients with BMLs and without BMLs (p > 0.05). CONCLUSIONS: Pain scores and GPE was not different between knee OA patients with and without baseline BMLs in this sample. Implications for Rehabilitation Both walking and strengthening exercises are effective means of improving pain in patients with knee osteoarthritis. In a relatively small sample, this study shows that the presence or absence of subchondral bone marrow lesions, as seen on magnetic resonance images, is not related to treatment outcomes.

Femoral fractures within resurfacing implants have been associated with bone necrosis, possibly resulting from heat generated by cement polymerization. The amount of heat generated depends on cement mantle volume and type of cement. Using finite element analysis, the effect of cement type and volume on thermal necrosis was analyzed. Based on CT-data of earlier implantations, two different models were created: a thick mantle model, representing a low-viscosity “cement filling” technique, and a thin mantle model, representing a high viscosity “cement packing” technique. Six cement types were analyzed. The polymerization heat generation and its effect on bone necrosis were predicted. In the thin cement mantle models, no thermal necrosis was predicted. Thick cement mantle models produced thermal necrosis at the cement–bone interface depending on cement type. In the worst case, 6% of the bone at the cement–bone interface became necrotic, covering almost the entire cross-sectional area. The current findings suggest a potential thermal drawback of thick cement mantles, although it is unclear whether thermal bone necrosis significantly affects implant fixation or increases the fracture risk. Furthermore, our study showed distinct differences between the heat generated and resulting thermal damage caused by the various cement types

Background and purpose Two contradictory cementing techniques (using an undersized stem versus a canal-filling stem) can both lead to excellent survival rates, a phenomenon known as the “French paradox”. Furthermore, previous studies have indicated that the type of bone supporting the cement mantle may affect implant survival. To further evaluate the mechanical consequences of variations in cementing technique, we studied the effect of implant size and type of bone supporting the cement mantle on the mechanical performance of cemented total hip arthroplasty, using finite element analysis. Methods In a generic 2-dimensional plane-strain finite element model of a transverse section of a cemented total hip arthroplasty with a Charnley-Kerboull stem, we varied implant size and type of bone supporting the cement mantle. The models were subjected to 2 × 106 cycles of an alternating loading pattern of torque and a transverse load. During this loading history, we simulated cement fatigue crack formation and tracked rotational stability of the implant. Results Canal-filling stems produced fewer cement cracks and less rotation than undersized stems. Cement mantles surrounded by trabecular bone produced more cement cracks and implant rotation than cement mantles surrounded by cortical bone. Interpretation Our investigation provides a possible explanation for the good clinical results obtained with canal-filling Charnley-Kerboull implants. Our findings also indicate that inferior mechanical properties are obtained with these implants if the cement is supported by trabecular bone, which may be minimized by an optimal cementing technique.

The "optimal" positioning of the cup in total hip arthroplasty can improve hip function and reduce wear, impingement and dislocation. The cup position is described as the spatial relation between the hip rotation centre and the pelvis and, as the cup orientation around the rotation centre. The first parameter affects hip balance and, if not managed properly, might result in poor function and leg length discrepancy. The second parameter is often "silent", unless impingement or dislocation occurs. However, inappropriate cup orientation can accelerate wear and cause early failure. As such, it is mandatory to get both right, taking into account multiple parameters: the stem position, the approach, the bearing surface, the cup coverage and the pelvic orientation during loading. In most cases a "standard" cup position is adequate. However, specific anatomic features might require an individualized approach. This paper aims at reviewing the parameters that impact on the optimal cup position. This should allow for more judicious choices in those particular cases.

This online questionnaire was initiated to investigate if a consensus on the treatment of distal radius fractures amongst orthopaedic surgeons in Belgium exist. Two cases were presented: an extra-articular fracture, with dorsal displacement (Frykman type I) and a displaced intra-articular fracture (Frykman type VII). Treatment of choice and rationale of choice were investigated. 158 responses were collected. In case of a Frykman type I, the majority of surgeons would have performed a closed reduction and intrafocal K-wiring (37.3%) or volar plating (34.8%). In case of a Frykman type VII, volar plating was the primary treatment of choice (66.5%), closed reduction and K-wiring was chosen in 24.7% and external fixation in 4.4%. We cannot conclude on a consensus in treatment choice amongst Belgian orthopaedic surgeons. Compared to previous research, an increase in the use of volar plating in intra- as well as in extra-articular distal radius fractures was noticed.

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.

BACKGROUND: Exercise effectiveness is related to adherence, compliance and drop-out. The aim of this study is to investigate if exercise-induced pain and health status are related to these outcomes during two exercise programmes in knee osteoarthritis patients. METHODS: Symptomatic knee osteoarthritis patients were randomly allocated to a walking or strengthening programme (N=19/group). At baseline, patients were categorized according to their health status. Exercise adherence and compliance were calculated and drop-out rate was registered. For exercise-induced pain, patients rated their pain on an 11-point numeric rating scale (NRS) before and after each training session. Before each session the maximal perceived pain of the last 24h (NRSmax24) was assessed. Patients rated their global self-perceived effect (GPE) on a 7-point ordinal scale after the intervention period. RESULTS: 53% of the participants felt they improved after the programme, 6 patients dropped out. The mean adherence and compliance rates were higher than .83 in both groups. Worse health and higher exercise-induced pain were seen in drop-outs. NRSmax24 during the first 3weeks did not significantly increase compared to baseline, but correlated negatively with adherence during the home sessions (-.56, p

We present a method for automatically estimating prosthesis migration from previous and follow-up CT image data. The method consists of the segmentation of the bone and prosthesis in both images, followed by a registration of both substructures. The migration is found by computing the difference between both transforms. In this work we assess the accuracy of the method for zero migration. The method was applied on data from a mechanical phantom and on patient data, both with zero migration. Our experiments show that an accuracy of less than 0.3 mm can be achieved in a clinical setting.