Variations in pelvic tilt during day-to-day activities after total hip arthroplasty measured with an ultrasound system.

INTRODUCTION: The pelvis plays a major role in the orientation of total hip arthroplasty (THA) implants and consequently, on the postoperative stability of the new hip joint. The relationship between the spine and pelvis affects the functional orientation of the acetabular cup, although this relationship differs between individuals and the positions encountered in everyday life. We believe this should be factored in when planning the THA procedure. This led us to conduct an in vivo ultrasound study to document the values of pelvic tilt in standing, sitting and lying positions in patients who have advanced hip osteoarthritis, before and after they undergo THA. HYPOTHESIS: The pelvic tilt when standing, sitting and lying supine does not change significantly after THA. MATERIALS AND METHODS: The pelvic tilt, defined as the angle between the anterior pelvic plane and a vertical line was measured using an ultrasound device in 30 patients before the THA procedure and again 6 months later in standing, sitting and lying positions. The measurements were done during an office visit with the patient on an examination table for the lying position, on a chair for the sitting position and with the heels and occiput against the wall for the standing position. RESULTS: The preoperative and 6-month postoperative pelvic tilt were -5.6̊±10.4̊ [-30.6̊; 11.7̊] and -5.8̊±7.9̊ [-20.6̊; 10.4̊] (p=0.4129) when standing, -44.5̊±6.10 [-53.8̊; -23.9̊] and -43.5̊±6.9̊ [-54.4̊; -17.3̊] (p=0.5760) when sitting, -88.3̊±5.1̊ [-99.3̊; -78.7̊] and -87.9̊±5.9̊ [-97.6̊; -72.4̊] (p=0.6106) when lying supine, respectively. There was no significant difference in the pelvic tilt before and 6 months after THA procedure. Variations of±5̊; ±5-10̊; ±10-15̊ and 15-20̊ were found in 72% (18); 20% (5); 4% (1) and 4% (1) of patients when lying supine, 56% (14); 36% (9); 8% (2); 0% (0) of patients when standing and 76% (19); 24% (6); 0% (0); 0% (0) when sitting. The mean variation for each patient between the preoperative and 6 months postoperative measurement was 4.8±3.4̊ [0.8̊; 10.4̊] (p=0.4129), 3.5±2.3̊ [0.2̊; 9.1̊] (p=0.5760), and 4.6̊±3.2̊ [1.2̊; 15.4̊] (p=0.6106) for the standing, sitting and lying positions respectively. CONCLUSION: The pelvic tilt does not significantly change 6 months after THA. Taking into account the various positions used in everyday life may help to optimize the implant position. We have described the use of an affordable, accurate and non-irradiating device that provides fast and easy measurements of pelvic tilt in various positions. LEVEL OF EVIDENCE: IV.

Orientation of the Scapula in the Standing Position.

OBJECTIVES: A new ultrasound-based device is proposed to non-invasively measure the orientation of the scapula in the standing position to consider this parameter for Total Shoulder Arthroplasty. The aim of this study was to assess the accuracy and reliability of this device. METHODS: Accuracy was assessed by comparing measurements made with the ultrasound device to those acquired with a three-dimensional (3D) optical localization system (Northern Digital, Canada) on a dedicated mechanical phantom. Three users performed 10 measurements on three healthy volunteers with different body mass (BMI) indices to analyze the reliability of the device by measuring the intra and interobserver variabilities. RESULTS: The mean accuracy of the device was 0.9°± 0.7 (0.01-3.03), 1.3°± 0.8 (0.03-4.55), 1.9°± 1.5 (0.05-5.76), respectively, in the axial, coronal, and sagittal planes. The interobserver and intraobserver variabilities were excellent whatever the BMI and the users experience. CONCLUSIONS: The device is accurate and reliable enough for the measurement of the scapula orientation in the standing position.

Total shoulder arthroplasty in France: An analysis of trends between 2009 and 2019 and projections to the year 2070.

BACKGROUND: Over the past decades, total shoulder arthroplasty (TSA) procedures have steadily increased in the United States and Europe. In France, the number of shoulder surgeries rose by 24.5% between 2012 and 2018, but no study has yet analyzed TSA trends based on patient characteristics. Therefore, the aim of our study was to use the French healthcare database to (1) analyze growth trends based on the patient's sex, age, and comorbidity profile and (2) estimate the most appropriate incidence rate (IR) projections to the year 2070. HYPOTHESIS: We hypothesize that in France, the upward trends are different for each sex and age group. MATERIALS AND METHODS: This study was conducted in France from 2009 to 2019 based on the French healthcare database (SNDS), which contains all nationwide procedures. Patients were analyzed by sex, age group (<65 years, 65-74 years, ≥75 years), and comorbidity profile (4 levels). IR trends per 100,000 population were inferred by patient age, sex, and comorbidity using data from the French hospital discharge database (PMSI) and population forecasts and censuses from the French National Institute of Statistics and Economic Studies (INSEE). Linear, Poisson, logistic, and Gompertz projection models were created to forecast IRs to the year 2070. RESULTS: Between 2009 and 2019, there was a sharper increase in IR in males (+155%; from 6.0 to 15.3) than in females (+118%; from 16.2 to 35.3) across all age groups. This increase was most significant in those younger than 65 years (+112%; from 2.3 to 4.9), in both males (+129%; from 2.1 to 4.8) and females (+99%; from 2.5 to 5.0). From 2012 to 2019, the proportion of patients with mild comorbidities increased by +92% (from 5,435 to 10,410 TSAs, i.e., from 56% to 61% of total procedures), unlike the other comorbidity profiles. All the projections modeled the data from 2009 to 2019 with minor deviations. However, the logistic projection was the most likely, with a 45% increase in the IR for the overall population by 2070 (from 17,175 to 25,338 TSAs), which will start to plateau in 2050. CONCLUSION: The IR has risen sharply in the overall population, as in all age, sex, and comorbidity categories, with the most significant growth seen in the<65 and 65-74 age groups and a shift toward patients with milder comorbidities. According to our projections, the IR will continue to be more significant in older patients, except for males, for whom the IR for those 65 to 74 years old will exceed that of those 75 and older around 2030. In the longer term, the IRs follow a logistic trend, reaching a plateau around 2050. Therefore, an increase in healthcare burden is to be expected to meet the growing demand for TSAs. LEVEL OF EVIDENCE: IV; Descriptive epidemiological study.

Design, Simulations and Tests of a Novel Force and Moments Sensor for Instrumented Knee Implants.

OBJECTIVES: Early identification of mechanical complications of total knee arthroplasties is of great importance to minimize the complexity and iatrogenicity of revision surgeries. There is therefore a critical need to use smart knee implants during intra or postoperative phases. Nevertheless, these devices are absent from commercialized orthopaedic implants, mainly due to their manufacturing complexity. We report the design, simulations and tests of a force and moments sensor integrated inside the tibial tray of a knee implant. METHODS: By means of a "tray-pillar-membrane" arrangement, strain gauges and metal additive technology, our device facilitates the manufacturing and assembly steps of the complete system. We used finite element simulations to optimize the sensor and we compared the simulation results to mechanical measurements performed on a real instrumented tibial tray. RESULTS: With a low power acquisition electronics, the measurements corroborate with simulations for low vertical input forces. Additionally, we performed ISO fatigue testings and high force measurements, with a good agreement compared to simulations but high non-linearities for positions far from the tray centre. In order to estimate the center of pressure coordinates and the normal force applied on the tray, we also implemented a small-size artificial neural network. CONCLUSION: This work shows that relevant mechanical components acting on a tibial tray of a knee implant can be measured in an easy to assemble, leak-proof and mechanically robust design while offering relevant data usable by clinicians during the surgical or rehabilitation procedures. SIGNIFICANCE: This work contributes to increase the technological readiness of smart orthopaedic implants.

Three-Dimensional Printed Knee Implants: Insights into Surgeons' Points of View.

Three-dimensional printing is a technology that has been developed and applied in several medical specialties, especially orthopedic surgery. Knee arthroplasty is the most commonly performed procedure. To fit the morphology of each knee, surgeons can choose between different standardized off-the-shelf implant sizes or opt for customized 3D-printed implants. However, routine adoption of the latter has been slow and faces several barriers. Existing studies focus on technical improvements or case studies and do not directly address the surgeon's perspective. Our study invited surgeons to express themselves freely and answer the question "What do you think about the manufacture of a prosthesis by 3D printing?". The questionnaire was completed by 90 surgeons. On average, they had more than 10 years of experience (52, 57.8% ± 10.2%), worked in public hospitals (54, 60% ± 10.1%), and performed between 0 and 100 prostheses per year (60, 66.7% ± 9.7%). They also reported not using planning software (47, 52.2% ± 9.7%), navigation systems, or robots (62, 68.9% ± 9.6%). Regarding the use of technological innovation, they agreed on the extra surgical time needed (67, 74.4% ± 9.0%). The answers obtained were classified according to two criteria: (i) opinions, and (ii) motivations. Among the respondents, 51 (70% ± 9.5%) had positive and 22 (30% ± 9.5%) had negative opinions about 3D printing. The motivations were distributed among seven categories (surgery, materials, costs, logistics, time, customization, and regulatory) and mainly related to "pre-surgery" and "post-surgery" concerns. Finally, the results showed that the use of navigation systems or robots may be associated with a more positive view of 3DP. The purpose of our study was to examine knee surgeons' perceptions of 3DP at a time of significant expansion of this technology. Our study showed that there was no opposition to its implementation, although some surgeons indicated that they were waiting for validated results. They also questioned the entire supply chain, including hospitals, insurance companies, and manufacturers. Although there was no opposition to its implementation, 3D printing is at a crucial point in its development and its full adoption will require advances in all areas of joint replacement.

Is a Total Hip Arthroplasty Stem in Varus a Risk Factor of Long-Term Mechanical Complication?

BACKGROUND: The impact of implanting cementless femoral stems in varus alignment on long-term mechanical complications remains poorly defined in the literature. The aim of our study was to compare survivorship and functional and radiographic outcomes of stems in varus alignment to those in neutral alignment with and average follow-up of 10 years. METHODS: This single-center, multisurgeon, retrospective case-control study compared a group of 105 total hip arthroplasty (THA) patients who had varus stem alignment (Varus Stem) to a matching group of 105 THA patients who had neutral stem alignment, operated on between January 2007 and December 2012. The primary outcome measure was implant survival. Secondary outcomes included functional (Harris Hip Score, Postel Merle d'Aubigné Score, thigh pain, dislocation and hip range of motion) and radiographic outcomes (radiolucency, osseointegration, heterotopic ossification, subsidence, and stress shielding). RESULTS: There was no significant difference in implant survival between the 2 groups with 95.7% (±2.46) in the Varus Stem group versus 97.7% (±1.64) in the Neutral Stem group (P = .41) after an average follow-up of 10 years. There was no significant difference in clinical and radiographic outcomes between groups. CONCLUSION: Cementless femoral stems in varus alignment were not the cause of mechanical complications with an average follow-up of 10 years. The comparison between groups in terms of implant survival, functional, and radiographic outcomes does not show any significant differences. Positioning a femoral stem in varus alignment may be an alternative for surgeons wishing to restore preoperative offset and to ensure satisfactory hip stability.

Functional safe zone for THA considering the patient-specific pelvic tilts: An ultrasound-based approach.

The usual Lewinnek orientation for cup positioning in total hip arthroplasty is not suitable for all patients as it does not consider the patient mobility. We propose an ultrasound-based approach to compute a Functional Safe Zone (FSZ) considering daily positions. Our goal was to validate it, and to evaluate how the input parameters impact the FSZ size and barycentre. The accuracy of the FSZ was first assessed by comparing the FSZ computed by the proposed approach and the true FSZ determined by 3D modelling. Then, the input parameters' impact on the FSZ was studied using a principal component analysis. The FSZ was estimated with errors below 0.5° for mean anteversion, mean inclination, and at edges. The pelvic tilts and the neck orientation were found correlated to the FSZ mean orientation, and the target ROM and the prosthesis dimensions to the FSZ size. Integrated into the clinical workflow, this non-ionising approach can be used to easily determine an optimal patient-specific cup orientation minimising the risks of dislocation.

Anterior pelvic plane estimation for total hip arthroplasty using a joint ultrasound and statistical shape model based approach.

Orienting properly the prosthetic cup in total hip arthroplasty is key to ensure the postoperative stability. Several navigation solutions have been developed to assist surgeons in orienting the cup regarding the anterior pelvic plane (APP), defined by both anterior superior iliac spines (ASIS) and the pubic symphysis. However acquiring the APP when the patient is ready for surgery, i.e., mainly in lateral decubitus, is difficult due to the contralateral ASIS being against the operating table. We propose a method to determine the APP from both (1) alternative anatomical landmarks which are easy to acquire with a navigated ultrasound probe and (2) a Statistical Shape Model (SSM) of the pelvis. After creating a pelvic SSM from 40 data, a SSM-based morphometric analysis has been carried out to identify the best anatomical landmarks allowing the easy determination of the APP. The proposed method has then been assessed with both in silico and in vivo experiments on respectively forty synthetic data, and five healthy volunteers. The in silico experiment shows the feasibility to determine the APP with an average error of 4.7∘ by only acquiring the iliac crest, the anterior superior iliac spine, the anterior inferior iliac spine, and the pubic symphysis. The average in vivo error using the ultrasound modality was 7.3∘ with an estimated impact on both the cup anteversion and inclination of 4.0∘ and 1.7∘ respectively. The proposed method shows promising results that could allow the determination of the APP in lateral decubitus with a clinically acceptable impact on the computation of the cup orientation.

Total knee arthroplasty in France: Male-driven rise in procedures in 2009-2019 and projections for 2050.

BACKGROUND: The number of Total Knee Arthroplasty (TKA) procedures has been rising steadily for several decades in Europe and the USA. The increase varies in pace across countries, with a gradual climb in northern and central Europe, a slowing in the USA, and an exponential surge in the UK. In France, a 32.2% rise in the number of TKA and unicompartmental knee arthroplasty procedures was documented between 2012 and 2018. However, no study has focussed specifically on changes in both TKA procedures and the features of TKA patients. The objective of this study was to use the French national healthcare database to evaluate (1) increases in TKA procedures according to sex and age, (2) whether TKA is being performed at increasingly younger ages, (3) whether the comorbidity profile at TKA is changing, and (4) whether the TKA incidence rate will stabilise in the future, with a projection for 2050. HYPOTHESIS: In France, the number of TKA procedures is rising in both males and females but the pace of the increases differs between sexes. MATERIAL AND METHOD: This study used data collected in France in 2009-2019, separately for different age groups and for males and females, in the French national healthcare database (Système national des données de santé, SNDS) that collects information on all surgical procedures performed nationwide. Based on information about the TKA procedures, we determined (1) the TKA incidence rates with their time trends and (2) indirectly, the comorbidity profiles of the patients at TKA. Linear, Poisson, and logistic models were built to predict incidence rates in 2030, 2040, and 2050. RESULTS: Between 2009 and 2019, the TKA incidence rate showed a steeper increase in males than in females (from 71.2 to 122.9 [+73%] vs. 124.2 to 181.0 [+46%], respectively). Although this increase was replicated in all age groups, it was sharper in patients younger than 65 years, in both males and females (from 20.9 to 37.9 [+82%] and 33.6 to 51.3 [+53%], respectively). During the study period, the number and proportion of patients increased in the group with mild comorbidities (from 40 093 to 67 430 TKAs, i.e., from 53.1% to 65.7% of all TKAs) but not in the other comorbidity groups. All projection models were validated. Nonetheless, the most likely scenario, provided by the logistic model, is a 33% rise by 2050 in both males and females (i.e., to 151 575 TKA procedures) with a plateau starting around 2030. CONCLUSION: Although the increase in TKA procedures is more marked in males than in females, the trends are similar in both sexes, with a sharper rise in the group younger than 65 years and a shift toward patients with milder comorbidities. In the longer term, incidence rate trends follow logistic dynamics, with a plateau starting around 2030. To meet the increasing demand, a corresponding development in relevant healthcare resources must be planned. LEVEL OF EVIDENCE: IV, descriptive epidemiological study.

Long-term outcomes of trapeziectomy with Gore-Tex® ligament reconstruction for trapezio-metacarpal osteoarthritis.

BACKGROUND: Trapezio-metacarpal osteoarthritis is a common condition for which the reference standard treatment after failure of non-operative measures is trapeziectomy. Several techniques have been devised to avoid proximal migration of the first metacarpal bone (M1) with impingement on the scaphoid bone. We have developed a Gore-Tex® ligament reconstruction technique that avoids potential complications of tendon harvesting. The objective of this study was to assess the long-term outcomes of this technique. HYPOTHESIS: Trapeziectomy with Gore-Tex® ligament reconstruction is a reliable option for providing lasting pain relief in patients with trapezio-metacarpal osteoarthritis. MATERIALS AND METHODS: We conducted an observational, single-centre, single-surgeon, retrospective cohort study in consecutive patients managed by primary trapeziectomy. We excluded patients with revision trapeziectomy or less than 10 years' follow-up. The primary outcome was event-free survival, defined as absence of revision surgery and of a numerical rating scale score for pain above 3/10. The secondary criteria were clinical tolerance of the Gore-Tex® implant and radiological changes. The patients were assessed at last follow-up either in person or during a teleconsultation. RESULTS: Of 78 included joints, 64 were assessed during patient visits and 24 by teleconsultation. At 10 years, the event-free survival rate was 91.3%, and 60.3% of patients were free of pain. Evidence of osteolysis was visible in 24% of patients. No patient experienced clinical intolerance of the Gore-Tex® implant. The mean Disabilities of Arm, Shoulder and Hand score was 25.5. Metacarpo-phalangeal hyperextension was significantly increased, to 30.6°, and the mean trapezial space ratio was significantly decreased, to 39.1% of the baseline value. CONCLUSION: Long-term event-free survival was high. Functional outcomes and pain were similar to previous reports. Trapeziectomy with Gore-Tex® ligament reconstruction obviates the need for tendon harvesting. Osteolysis developed in some patients but did not correlate with clinical intolerance. Long-term clinical and radiological monitoring is in order after Gore-Tex® implantation. LEVEL OF EVIDENCE: IV, Observational, single-centre, single-surgeon, retrospective cohort study.

Optimal definitions for computing HKA angle in caos: an in-vitro comparison study.

The goal of this study was to assess and compare the precision and accuracy of nine and seven methods usually used in Computer Assisted Orthopedic Surgery (CAOS) to estimate respectively the Knee Center (KC) and the Frontal Plane (FP) for the determination of the HKA angle (HKAA). An in-vitro experiment has been realized on thirteen cadaveric lower limbs. A CAOS software application was developed and allowed the computation of the HKAA according to these nine KC and seven FP methods. The precision and the accuracy of the HKAA measurements were measured. The HKAA precision was highest when the FP is determined using the helical method. The HKAA accuracy was highest using the helical approach to determine the FP and either the notch or the tibial spines to determine the KC. This study shows that the helical approach to determine the FP and either the notch or the middle of tibia spines are the combinations that provide both a good enough accuracy and precision to estimate the HKA.

Towards markerless computer assisted surgery: Application to total knee arthroplasty.

PURPOSE: A new approach is proposed to localise surgical instruments for Computer Assisted Orthopaedic Surgery (CAOS) that aims at overpassing the limitations of conventional CAOS solutions. This approach relies on both a depth sensor and a 6D pose estimation algorithm. METHODS: The Point-Pair Features (PPF) algorithm was used to estimate the pose of a Patient-Specific Instrument (PSI) for Total Knee Arthroplasty (TKA). Four depth sensors have been compared. Three scores have been computed to assess the performances: The Depth Fitting Error (DFE), the Pose Errors, and the Success Rate. RESULTS: The obtained results demonstrate higher performances for the Microsoft Kinect Azure in terms of DFE. The Occipital Structure core shows better behavior in terms of Pose Errors and Success Rate. CONCLUSION: This comparative study presents the first depth-sensor based solution allowing the intraoperative markerless localization of surgical instruments in orthopedics.

Antibiotic Therapy for 6 or 12 Weeks for Prosthetic Joint Infection.

BACKGROUND: The management of prosthetic joint infection usually consists of a combination of surgery and antimicrobial therapy. The appropriate duration of antimicrobial therapy for this indication remains unclear. METHODS: We performed an open-label, randomized, controlled, noninferiority trial to compare 6 weeks with 12 weeks of antibiotic therapy in patients with microbiologically confirmed prosthetic joint infection that had been managed with an appropriate surgical procedure. The primary outcome was persistent infection (defined as the persistence or recurrence of infection with the initial causative bacteria, with an antibiotic susceptibility pattern that was phenotypically indistinguishable from that at enrollment) within 2 years after the completion of antibiotic therapy. Noninferiority of 6 weeks of therapy to 12 weeks of therapy would be shown if the upper boundary of the 95% confidence interval for the absolute between-group difference (the value in the 6-week group minus the value in the 12-week group) in the percentage of patients with persistent infection within 2 years was not greater than 10 percentage points. RESULTS: A total of 410 patients from 28 French centers were randomly assigned to receive antibiotic therapy for 6 weeks (205 patients) or for 12 weeks (205 patients). Six patients who withdrew consent were not included in the analysis. In the main analysis, 20 patients who died during follow-up were excluded, and missing outcomes for 6 patients who were lost to follow-up were considered to be persistent infection. Persistent infection occurred in 35 of 193 patients (18.1%) in the 6-week group and in 18 of 191 patients (9.4%) in the 12-week group (risk difference, 8.7 percentage points; 95% confidence interval, 1.8 to 15.6); thus, noninferiority was not shown. Noninferiority was also not shown in the per-protocol and sensitivity analyses. We found no evidence of between-group differences in the percentage of patients with treatment failure due to a new infection, probable treatment failure, or serious adverse events. CONCLUSIONS: Among patients with microbiologically confirmed prosthetic joint infections that were managed with standard surgical procedures, antibiotic therapy for 6 weeks was not shown to be noninferior to antibiotic therapy for 12 weeks and resulted in a higher percentage of patients with unfavorable outcomes. (Funded by Programme Hospitalier de Recherche Clinique, French Ministry of Health; DATIPO ClinicalTrials.gov number, NCT01816009.).

Does total wrist denervation give reliable long-term results? Survival curve with an average follow-up of 8.2 years.

INTRODUCTION: Pain is the main reason why patients consult for degenerative and posttraumatic wrist conditions. While the many surgical techniques make choosing the appropriate procedure difficult, total wrist denervation, which has an "analgesic" aim, remains an accessible therapeutic solution to treat this symptomatology. Nevertheless, long-term results remain controversial, and few studies have focused on the survival of this procedure. HYPOTHESIS: Total wrist denervation provides lasting pain relief. PATIENTS AND METHODS: This was a single center, single operator (DLN), retrospective observational study. We analyzed 63 wrists. The mean age at the time of the procedure was 53.7 years. We verified the primary endpoint for survival, which included no further analgesic procedures and no significant residual pain (NRS≤3). Patient satisfaction and the quality of the wrist function were also assessed. RESULTS: The mean follow-up was 8.2 years. Some of the patients (12.7%) did not respond to treatment. We reported 1 neuroma of the superficial sensory branch of the radial nerve, 2 CRPS and 11 revision surgeries. We observed that the treatment became less effective over time. The median survival was 8.8 years. The survival rate of the procedure fell to 13.5% at the last follow-up. The mean residual pain was 3.4 on a numerical rating scale and the mean DASH score was 23.5. The mean satisfaction level, on a scale from 0 to 10, was 7.3 and most patients (79.6%) would undergo this procedure again. DISCUSSION: Survival of the total wrist denervation at the last follow-up was low in our study. Even though the treatment became less effective over time, the quality of the wrist function remained satisfactory and similar to the different studies previously published on the subject. There were very few complications and revisions. CONCLUSION: Total wrist denervation therefore remains an interesting surgical solution for patients with chronic wrist pain as it preserves mobility. LEVEL OF EVIDENCE: IV; Single center, single operator retrospective observational study.

Statistical Shape Modeling to Determine the Anterior Pelvic Plane for Total Hip Arthroplasty.

The anterior pelvic plane (APP) defined by both iliac spines and the pubic symphysis, is essential in total hip arthroplasty (THA) for the orientation of the prosthetic cup. However, the APP is nowadays still difficult to determine in computer assisted orthopedic surgery (CAOS). We propose to use a statistical shape model (SSM) of the pelvis to estimate the APP from ipsilateral anatomical landmarks, more easily accessible during surgery in computer assisted THA with the patient in lateral decubitus position. A SSM of the pelvis has been built from 40 male pelvises. Various ipsilateral anatomical landmarks have been extracted from these data and used to deform the SSM. Fitting the SSM to several combinations of these landmarks, we were able to reconstruct the pelvis with an accuracy between 2.8mm and 4.4mm, and estimate the APP inclination with an angular error between 1.3° and 2.8°, depending on the landmarks fitted. Results are promising and show that the APP could be acquired during the intervention from ipsilateral landmarks only.

Glenoid subchondral bone density in osteoarthritis: A comparative study of asymmetric and symmetric erosion patterns.

BACKGROUND: Recent studies have shown variations in glenoid bone density in asymmetric wear patterns but have yet to analyze non-arthritic or concentrically worn glenoids. QUESTIONS/PURPOSES: The purpose of this study is to characterize and compare subchondral glenoid bone densities in both non-arthritic and A1, A2, B1, B2 and B3 osteoarthritic glenoids, as well as to assess uniformity in symmetric and asymmetric erosion wear patterns. METHODS: In all, 150 computerized tomography (CT) scans containing equal numbers of non-arthritic (N), A1, A2, B1, B2 and B3 glenoids were segmented semi-automatically. Each reconstructed glenoid was divided first into anterior and posterior quadrants, and then further subdivided into four quadrants. Volumes of interest (VOI) were defined at depths of 0-2.5mm (Zone A), 2.5-5mm (Zone B) and 5-7.5mm (Zone C). Average bone densities were measured at each VOI depth and in each quadrant. RESULTS: Osteoarthritic glenoids had higher mean bone densities than N glenoids. Mean bone densities were uniform amongst all quadrants for N glenoids, but not for osteoarthritic glenoids. In A1 glenoids, the antero-superior quadrant was less dense in Zone C. A2 glenoids had increased bone density measured posteriorly in Zones B and C. In B1 and B2 glenoids, Zones B and C demonstrated increased bone densities of posterior quadrants compared to anterior quadrants. B3 glenoids presented similar results as A1 and A2 glenoids. Cystic changes were more pronounced in anterior quadrants of A2, B1, B2 and B3 glenoids. CONCLUSION: This study demonstrates that osteoarthritic glenoids have greater bone density than non-arthritic glenoids, independent of depth of interest. It also confirms that N glenoids have uniform erosion wear patterns and that B1 and B2 glenoids have irregular wear patterns. It is the first study to reveal that A1, A2 and B3 glenoids, though geometrically symmetrical, have irregular bony densities similar to B2 glenoids. These findings have clinical implications for reaming the glenoid and implant fixation. LEVEL OF EVIDENCE: Basic Science, Anatomy, Imaging.

Modeling Early Stages of Bone and Joint Infections Dynamics in Humans: A Multi-Agent, Multi-System Based Model.

Diagnosis and management of bone and joint infections (BJI) is a challenging task. The high intra and inter patient's variability in terms of clinical presentation makes it impossible to rely on a systematic description or classical statistical analysis for its diagnosis. Advances can be achieved through a better understanding of the system behavior that results from the interactions between the components at a micro-scale level, which is difficult to mastered using traditional methods. Multiple studies from the literature report factors and interactions that affect the dynamics of the BJI system. The objectives of this study were (i) to perform a systematic review to identify relevant interactions between agents (cells, pathogens) and parameters values that characterize agents and interactions, and (ii) to develop a two dimensional computational model of the BJI system based on the results of the systematic review. The model would simulate the behavior resulting from the interactions on the cellular and molecular levels to explore the BJI dynamics, using an agent-based modeling approach. The BJI system's response to different microbial inoculum levels was simulated. The model succeeded in mimicking the dynamics of bacteria, the innate immune cells, and the bone mass during the first stage of infection and for different inoculum levels in a consistent manner. The simulation displayed the destruction in bone tissue as a result of the alteration in bone remodeling process during the infection. The model was used to generate different patterns of system behaviors that could be analyzed in further steps. Simulations results suggested evidence for the existence of latent infections. Finally, we presented a way to analyze and synthesize massive simulated data in a concise and comprehensive manner based on the semi-supervised identification of ordinary differential equations (ODE) systems. It allows to use the known framework for temporal and structural ODE analyses and therefore summarize the whole simulated system dynamical behavior. This first model is intended to be validated by in vivo or in vitro data and expected to generate hypotheses to be challenged by real data. Step by step, it can be modified and complexified based on the test/validation iteration cycles.

Predicting epiphyseal screw length in anterior plating of distal radial fractures.

The purpose of this study was to determine whether optimal epiphyseal screw length could be predicted with reference to a given diaphyseal screw length when fixating a plate to the anterior surface of the distal radius. Computerized tomography scans of 40 wrists of 28 men and 12 women were semi-automatically segmented. A virtual anterior plate model was fixed to the distal radius. The mean maximal appropriate length of one diaphyseal screw and of the four distal epiphyseal screws were measured and linear regression analyses were performed. We found that the epiphyseal screw lengths were highly correlated to the diaphyseal screw length. Based on the data derived from measurements, we recommend epiphyseal screw lengths from ulnar to radial of 18, 18, 20 and 16 mm, respectively, if the diaphyseal screw is 14 mm or less. For diaphyseal screws longer than 14 mm we recommend epiphyseal screws of 20, 20, 22 and 18 mm. Using these recommended screw lengths as general guidelines may reduce the risk of intra-operative and postoperative extensor tendon injury.

Accuracy and Precision of an Ultrasound-Based Device to Measure the Pelvic Tilt in Several Positions.

OBJECTIVES: A new ultrasound-based device is proposed to measure the patient-specific pelvic tilt in different daily positions. The aim of this study was to assess the accuracy of this device as well as the intraobserver and interobserver precisions. METHODS: The accuracy was assessed by performing several tilt measurements with the device on a testing mechanical bench. The error was defined as the difference between the tilt measured with the device and the tilt provided by this test bench. Three physicians, a novice, an intermediate, and an expert user, were also asked to perform 10 measurements on 3 healthy volunteers with low, medium, and high body mass indices to analyze the intraobserver and interobserver precisions. These 10 measurements were performed in the standing, sitting, and supine positions. RESULTS: The mean accuracy of the device ± SD was 1.1° ± 0.7° (range, 0°-4.0°). The interobserver and intraobserver precisions were excellent whatever the body mass index and good to excellent according to the positions. There was no learning curve, and the time required to complete the measurements was approximately 5 minutes. CONCLUSIONS: This study presents an accurate and precise noninvasive device for measurement of the pelvic tilt in different positions.