A national survey to assess the state of anatomy teaching in France across various disciplines and professions.

PURPOSE: To investigate the current practices in anatomy teaching at French universities in 2023. METHODS: On January 10, 2023, a questionnaire was sent to all members of the official list of the French Medical College of Professors of Anatomy. Each Anatomy centre was asked to complete this online form only once. The questionnaire covered several key themes, including broad questions, dissections practices, "virtual" dissections, teaching methods and teaching staff. RESULTS: The questionnaire was completed by 26/28 anatomy centres. Access to body donor dissection is reported to be mandatory in 15 of the 26 centers (58%), optional in 10 centers (38%), and "tolerated" in one center (4%). Fifteen of 26 centers (58%) reported having a virtual dissection table for teaching anatomy. Concerning the teaching of anatomy via live ultrasound, 10 out of 26 centers (38%) reported providing it. Regarding the teaching methods used for medical students, chalk and board lectures are the most common method, although the intensity of use varies. Most lectures are given with chalk and board in 42% (11/26) of the centers. In about 73% (19/26) of the centers, tablet lectures are used. Regarding anatomy teachers, it was reported that in 24/26 anatomy centres (92%), more than 50% of the courses for medical students are taught by professors holding the chair of anatomy (21/26 professors (81%), 3/26 associate professors (12%)). CONCLUSION: The present study endeavors to contribute to the existing body of knowledge on anatomy education by offering insights into the current practices in French universities.

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.

Assessment of using ultrasonography to teach abdominal and cervical anatomy in French medical curricula.

PURPOSE: The objective of this work was to assess, in a quantitative and qualitative way, the teaching of cervical and abdominal anatomy via ultrasound for medical students. METHODS: For several years, tutorials on the study of anatomy through use of ultrasound on the living organism have been given at the Medical School of Brest. These sessions have focused on cervical anatomy and abdominal anatomy. Students were invited to quantitatively assess these lessons by taking two tests containing questions on both cervical and abdominal anatomy and ultrasound technique: a pre-test administered at the beginning of the year and a post-test at the end of the year. In addition, a qualitative assessment was carried out at the end of the year. Ten statements were presented, and students were asked to indicate their agreement or disagreement to a four-point Likert scale. RESULTS: One hundred and twelve students answered all the questions on the pre-test with an average of 13.4 correct answers out of 20. Forty-eight students answered all the questions on the post-test with an average of 14.6/20. Twenty-six students who benefited from the courses gave positive feedback about the workshops on the qualitative assessment at the end of the year (median scores > = 3/4). CONCLUSION: The results of this work suggest that the use of ultrasound makes a positive contribution to the teaching of anatomy. The students interviewed think this type of tutorial should be an integral part of the anatomy curriculum at our university. In addition, this type of instruction can serve to introduce the use of ultrasound itself in a practical learning setting.

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.

Long-term survival of the Lefèvre retentive cup: 12-year follow-up analysis of 466 consecutive cases.

INTRODUCTION: The Lefèvre retentive cup is a salvage solution for total hip replacement at high risk of dislocation. Only a few studies have reported the medium or long-term survival; most often, only a small number of patients were included in these studies. This led us to conduct a retrospective analysis of a large population to determine: 1) the 10-year survival rate after primary or revision arthroplasty, 2) the complication rate. HYPOTHESIS: The dislocation rate is<5% for revision arthroplasty and<2% for primary arthroplasty. MATERIAL AND METHODS: This single-center retrospective study included 466 consecutive total hip replacements performed with the Lefèvre retentive cup with a 12-year theoretical minimum follow-up (1/1/1998 to 31/8/2006). There were 257 indications for primary arthroplasty and 209 for revision arthroplasty. The cohort had 316 women and the mean age at surgery was 72.9years (30.2-89.9). The mean follow-up was 10.2±5 years (0.1-19.3). A statistical analysis was done based on the Kaplan-Meier survival curves in two subsets of patients: primary and revision surgery. RESULTS: At the final review, 264 patients had died because of reasons unrelated to the procedures (mean 7.8±4.7years after the procedure), 48 were lost to follow-up (mean 3.0±3.3years after the procedure), and 39 patients (8%) had undergone acetabular revision of which 12 were for infection (2.5%), 25 were for loosening (5.4%) (5 femoral loosening only) and 2 were for dislocation (0.4%). In all, there were 10/466 dislocations (2.1%) of which 5/257 (1.9%) were in the primary group and 5/209 (2.4%) were in the revision group: 2 had a cup exchange and 8 were reduced by closed procedures. The probability of survival free of mechanical complications at 10years was estimated at 94.8%±1.6% (95% CI: 91.6%-98.0%) for the primary group and 87.8%±2.7% (95% CI: 82.4%-93.2%) for the revision groups (p=0.0017). There were 39 re-operations in the overall cohort: 1/257 (0.4%) for dislocation, 7/257 (2.7%) for aseptic loosening and 3/257 (1.2%) for infection in the primary group, while in the revision group, 1/209 (0.5%) was for dislocation, 18/209 (8.6%) for aseptic loosening and 9/209 (4.3%) for infection. CONCLUSION: The Lefèvre retentive cup has good long-term survival with a low mechanical complication rate, both in primary and revision surgery. To us, this implant appears to be a reliable salvage procedure for total hip replacement in patients at high risk for dislocation. LEVEL OF EVIDENCE: IV; retrospective study without control group.

Minimally invasive posterolateral hip approach with SPARTAQUUS (Spare the Piriformis And Respect The Active QUadratus femoris and gluteus mediUS) technique.

Interest in the different surgical approaches to total hip arthroplasty remains high, but without any real consensus on which approach is the most beneficial. Several recent technical innovations have made it possible to reduce the risk of dislocation, therefore improving the efficacy of the posterolateral approach. Since 2003, we have been using a modified minimally invasive posterolateral approach called SPARTAQUUS (Spare the Piriformis And Respect The Active QUadratus femoris and gluteus mediUS), which spares the piriformis tendon, the quadratus femoris muscle and the gluteus medius muscle, and involves direct capsular repair. The "active posterosuperior hammock" effect of the piriformis tendon is therefore coupled with the "passive posterosuperior hammock" effect of the capsular repair, thus limiting the risks of posterior dislocation of the prosthetic hip joint.

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.

The Lefèvre retentive cup compared with the dual mobility cup in total hip arthroplasty revision for dislocation.

BACKGROUND: Limiting the risk of dislocation is one of the main aims of both dual mobility and Lefèvre retentive cups. However, these devices have never been compared. The goal of our study was to compare these devices in total hip arthroplasty revisions for instability. The judgement criterion was non-recurrence of dislocation in a follow-up period of eight years. METHODS: This retrospective case-control study compared two continuous paired series of total hip arthroplasty revisions for instability. These series included 63 patients and 159 patients with implantation of a Lefèvre retentive cup and a dual mobility cup, respectively. RESULTS: The success rate at eight years (i.e., no recurrence) was 91 ± 0.05% and 95 ± 0.02% in the Lefèvre retentive cup and dual mobility groups, respectively. The difference was not statistically significant (p = 0.6). CONCLUSION: It seems that the Lefèvre retentive cup provides comparable outcomes with the dual mobility cup in the total hip arthroplasty revisions for instability, avoiding recurrence in long term.

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.

Advantages of expulsion-proof pins in the treatment of olecranon fractures with tension band wiring: Comparison with a control group.

INTRODUCTION: Tension band wiring is considered the standard treatment for transverse olecranon fractures. Its main complications are pin migration and discomfort caused by the hardware. We have designed and used "expulsion-proof" pins (EPP) that are shaped to prevent migration and reduce discomfort. This study compared the complication rate between our device and Kirschner pins (controls). HYPOTHESIS: We hypothesised that EPP would have lower migration rates and fewer complications than standard Kirschner pins. MATERIALS AND METHODS: This retrospective, single-center, multi-operator, observational, study examined data from January 1996 to December 2014. The primary outcome was the occurrence of pin migration. Secondary outcomes were the occurrence of one or more additional complications and the hardware removal rate. RESULTS: The study enrolled 101 patients: 53 (52.4%) with expulsion-proof pins and 48 (47.6%) controls. The mean follow-up was 240.6days in the EPP group and 268.9days in the control group. No cases of migration (0%) were found in the EPP group versus 21 (43.7%) cases in the controls (p<0.05). One or more complications occurred in 18 (33.9%) patients in the EPP group versus 46 (95.8%) controls (p<0.05). There was material discomfort in 13 (24.5%) cases and 1 (1.9%) case of secondary displacement in the EPP group, compared with 38 (79.2%) and 7 (14.6%) cases, respectively, in the controls (p<0.05). The rate of delayed consolidation was statistically identical in the two groups (p=0.103). The hardware was removed in 13 (24.5%) cases in the EPP group compared with 36 (75%) controls (p<0.05). CONCLUSION: EPPs are useful for management of olecranon fractures treated via TBW: the pins do not migrate and can reduce complications, discomfort, secondary displacement, and the hardware removal rate. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

What is the best hip center location method to compute HKA angle in computer-assisted orthopedic surgery? In silico and in vitro comparison of four methods.

BACKGROUND: In computer-assisted orthopedic surgery, the hip center (HC) can be determined by calculating the center of rotation of the femur in relation to the pelvis. Several methods are available: Gamage, Halvorsen, Pivot or Least-Moving Point (LMP). To our knowledge, no studies have compared these four methods. We therefore conducted in silico and in vitro experiments to assess whether their accuracy and precision in locating the HC and calculating the hip-knee-ankle (HKA) angle were equivalent. HYPOTHESIS: The four methods show similar accuracy and precision. PATIENTS AND METHODS: The in silico experiment assessed the independent influence of four parameters (camera noise, acetabular noise, movement amplitude, and number of circumductions) on accuracy. The accuracy and precision of the four methods and the impact on HKA ankle calculation were assessed in an in vitro study on six cadaver limbs. RESULTS: In the in silico experiment, all differences according to method were significant (p<0.0002). The Pivot method was the most accurate for acetabular and camera noise, number of circumductions, and movement amplitude. With the LMP, Pivot, Gamage and Halvorsen methods, error was respectively 23.07±8.40 (range 2.10-54.67) mm, 1.98±081 (0.15-4.89) mm, 28.18±3.42 (18.57-37.60) mm and 2.84±1.46 (0.11-9.44) mm depending on camera noise, 1.65±0.72 (0.13-4.80) mm, 0.52±0.22 (0.05-1.23) mm, 3.02±0.57 (0.60-4.78) mm and 0.61±0.27 (0.04-1.82) mm depending on movement amplitude, 0.50±0.20 (0.05-1.34) mm, 0.18±0.08 (0.01-0.44) mm, 0.36±0.14 (0.03-0.80) mm and 0.21±0.09 (0.01-0.55) mm depending on number of circumductions, and 11.30±5.77 (0.56-37.87) mm, 2.78±1.47 (0.10-8.77) mm, 88.08±8.85 (60.59-117.79) mm and 24.33±9.82 (1.40-66.17) mm depending on acetabular noise. In the in vitro experiment, differences were non-significant between the Pivot and LMP methods (p>0.98) and between the Gamage and Halvorsen methods (p>0.65). With the LMP, Pivot, Gamage and Halvorsen methods, precision was respectively 8.2±4.6 (3.3-23.6) mm, 7.3±3.6 (3.4-14.1) mm, 33.6±19.1 (4.7-111.4) mm and 35.0±25.0 (4.7-132.5) mm. Accuracy was 13.5±8.2 (3.2-40.7) mm. 12.3±6.4 (3.2-23.6) mm, 47.0±33.3 (6.2-176.6) mm and 40.3±27.8 (6.1-130.3) mm. The LMP and Pivot methods were thus more accurate and more precise than the Gamage and Halvorsen methods. HKA angle error was 1.1±0.9° (0.1-3.7) and 0.9±0.8° (0.0-2.5) with the LMP and Pivot methods, and 3.2±2.7° (0.0-12.7) and 3.8±3.5° (0.0-13.3) with the Gamage and Halvorsen methods. DISCUSSION: The study highlighted differences between the four methods of HC location in computer-assisted surgery; the Pivot method was the most accurate and precise, thus falsifying the study hypothesis. LEVEL OF EVIDENCE: III, prospective comparative in silico and in vitro study.

Stereoscopic visual area connectivity: a diffusion tensor imaging study.

PURPOSE: To study the white matter tracts connecting the different stereoscopic visual areas of the brain by diffusion tensor imaging. METHODS: In a previous study, we identified the cortical activations to a visual 3D stimulation in 12 subjects using functional MRI (fMRI). These areas of cortical activations [V5, V6, lateral occipital complex (LOC) and intra parietal sulcus areas (IPS)] in addition to the lateral geniculate nucleus (LGN) and the primary visual area V1 were chosen as regions of interest (ROIs). We studied by deterministic tractography the connections existing between these ROIs. RESULTS: Found connections were divided into three groups. The first group entails the geniculo-extrastriate connections. LGN was connected to V5, V6, IPS and LOC. These fibers course in the inferior longitudinal fascicule. The second group comprises the associative fibers. V1 was connected to V5 and LOC through the transverse occipital fascicule on one hand, and, to V6 and IPS through the stratum proprium cuni on the other hand. Connections between V5 and LOC, and V6 and IPS course within the vertical occipital fascicule. The third group contains commissural fibers. Forceps major entailed the connections between both V1, both V6, both IPS and IPS and contralateral V6. LGN was connected to contralateral LGN, V1, V6, IPS and LOC. CONCLUSIONS: We have elucidated numerous connections between the visual areas and the LGN. Generalization of these results to the remainder of the population must remain prudent due to the limited number of subjects in this study.

Midterm Survivorship of the Lefèvre Constrained Liner: A Consecutive Multisurgeon Series of 166 Cases.

BACKGROUND: Constrained liners are used as part of a salvage procedure to provide stability for patients at high risk for dislocation after a total hip arthroplasty. However, no recent studies exist highlighting their effectiveness and/or limitations. METHOD: This prospective review included 166 consecutive hip arthroplasties, either primary (27%) or revision (73%), with a unique design of a constrained liner: Lefèvre retentive cup. There were 113 females (69%), and the average age at index surgery was 75.9 years (range, 35-94). The mean follow-up was 6.2 years (range, 0.3-11). RESULTS: Twenty patients had a reoperation; 10 for infection (4 acute and 6 chronic joint infection) and 10 for cup failure (5 fixation failure, 3 aseptic loosening, and 2 dislocation). Ten-year survivals for cup revision were 89% (CI, 83-94) and 92% (CI, 89-97) for all revision and revision for noninfectious reasons, respectively. When solely evaluating for dislocation, the survival at 10 years was 99% (CI, 97-100). Considering primary and revision cases, 10-year survivals cup revision for aseptic reasons were 92.4% (CI, 84-100) and 92.5% (CI, 87-98), respectively. CONCLUSIONS: The Lefèvre retentive cup demonstrated excellent 10-year's survivorship. With the rate of aseptic loosening around 2% and a dislocation rate around 1%, the cup is as effective as other available devices and is therefore a cost-effective tool to reduce the risk of dislocation in at-risk patients undergoing hip arthroplasty.

Direct geniculo-extrastriate pathways: a review of the literature.

PURPOSE: The aim of this paper is to review the literature on direct geniculo-extrastriate pathways with special attention to 3D extrastriate visual areas. METHODS: A literature review was realized using PubMed and Google Scholar. "Lateral geniculate nucleus", "geniculo-extrastriate pathways" and "white matter fiber tracts" were among the keywords used. RESULTS: Existence of geniculo-extrastriate connections was first hypothesized by the clinical observations of Riddoch's syndrome in patients with striate cortex (primary visual area, V1) lesions. Robust histological proof of geniculo-extrastriate pathways exists in monkeys. In humans, these pathways were tested through functional magnetic resonance imaging (fMRI), electro- and magneto-physiological paradigms. Conversely, only indirect proof of the connection between lateral geniculate nucleus and V5 exists. To our knowledge there were not any anatomical studies of geniculo-extrastriate connections in humans. CONCLUSION: Few human studies take interest in geniculo-extrastriate pathways. Only indirect proof of geniculo-extrastriate pathways exists in humans.

Building and tracking root shapes.

An algorithm aiming at robust and simultaneous registrations of a sequence of 3-D shapes was recently presented by Jacq et al. [IEEE Trans. Biomed. Eng., vol. 55, no. 5, 2008]. This algorithm has to carry out an implicit representation of their common root shape (RS). A particular emphasis was put on the median consensus shape, which is a specific type of RS. Unlike this previous study, mainly focusing on the algorithm foundations while dealing with very specific applications examples, this paper attempts to show the versatility of the RS concept through a set of three problems involving a wider scope of application. The first problem copes with the design of prosthetic cortical plates for the hip joint. It shows how an explicit reconstruction of the RS, coming with its consensus map, could bring out an intermediary anatomical support from which pragmatic choices could be made, thereby performing a tradeoff between morphological, surgical, and production considerations. The second problem addresses in vivo real-time shoulder biomechanics through a miniature 3-D video camera. This new protocol implicitly operates through RS tracking of the content of virtual spotlights. It is shown that the current medical-oriented protocol, while operating within expert offices through low-cost equipments, could challenge high-end professional equipments despite some limitations of the 3-D video cameras currently available. The last problem deals with respiratory motions. This is an auxiliary measurement required by some medical imaging systems that can be handled as a basic application case of the former new protocol.

Greater trochanter displacements after Charnley's trochanterotomy, during passive hip movements: a real-time 3D cadaveric approach.

Non-unions of greater trochanter (GT) fractures or osteotomies are the source of frequent complications. Two muscles are involved in the genesis of such non-unions, the gluteus medius and the gluteus minimus. Literature says that, during hip flexion, their terminal insertions on the faces of the GT generate an anterior translation of the GT responsible for contact loosening and healing defect. The main goal of this paper was to assess this hypothesis into the 3D space and to quantify the 3D displacements (three translations and three rotations) of the GT after trochanterotomy during passive motions of the hip joint (flexion, abduction-adduction, internal and external rotation). Therefore, we used 13 fresh cadaveric hips, on which we registered the GT displacements thanks to a 3D infrared localizer. An ultra low weight dynamic reference based has been developed to track the motion of the GT without any interference. The results have shown rotatory displacements of the GT around the three axes. This produces a posterior and lateral opening of the osteotomy site associated with a posterior rotatory shear of the GT. Above 45 degrees of hip flexion these three rotations combine together to exert shear on the osteotomy site which is harmful to the osteosynthesis material and the consolidation potential and may explain implant loosening.

Toward a dynamic approach of THA planning based on ultrasound.

The risk of dislocation after THA reportedly is minimized if the acetabular implant is oriented at 45 degrees inclination and 15 degrees anteversion with respect to the anterior pelvic plane. This reference plane now is used in computer-assisted protocols. However, this static approach may lead to postoperative instability because the dynamic variations of the pelvis influence effective cup orientation and are not taken into account in this approach. We propose an ultrasound tool to register the preoperative dynamics of the pelvis for THA planning during computer-assisted surgery. To assess this pelvic behavior and its consequences on implant orientation, we tested a new 2.5-dimensional ultrasound-based approach. The pelvic flexion was registered in sitting, standing, and supine positions in 20 subjects. The mean values were -25.2 degrees +/- 5.8 degrees (standard deviation), 2.4 degrees +/- 5.1 degrees , and 6.8 degrees +/- 3.5 degrees , respectively. The mean functional anteversion varied by 26 degrees and the mean functional inclination by 12 degrees depending on the pelvic flexion. We therefore recommend including dynamic pelvic behavior to minimize dislocation risk. The notion of a safe zone should be revisited and extended to include changes with activity.

Diagnosis of anterior cruciate ligament rupture in an emergency department.

BACKGROUND: Although an early diagnosis is crucial to optimize outcomes after injury to the anterior cruciate ligament (ACL), little is known about the performance of emergency room physicians in diagnosing this injury. HYPOTHESIS: We hypothesized that emergency room physicians would miss a substantial proportion of ACL ruptures. STUDY: : Prospective comparative study. METHODS: From April 2004 through October 2004, all patients aged 15 to 55 years and presenting at the emergency department of a teaching hospital for acute knee injury without fracture or multiple injuries were included. The results of a standardized examination conducted by the emergency physicians were compared with the findings by a sports medicine specialist 5 +/- 2 days later. Magnetic resonance imaging was performed when the specialist found a positive Lachman's test and was used as the reference standard for diagnosing ACL rupture. Cohen's kappa test was used to evaluate agreement between emergency physicians and the specialist. RESULTS: Of the 79 included patients, 27 (34.2%) had a diagnosis of ACL rupture established by the specialist and confirmed by magnetic resonance imaging. Agreement was poor between emergency physicians and the sports medicine specialist regarding popping sound, instability, joint effusion, a positive Lachman's test, and a diagnosis of ACL rupture. Emergency physicians diagnosed only 7 of the 27 ACL ruptures. CONCLUSION: Emergency physicians missed a substantial proportion of acute ACL ruptures. Efforts are needed to improve their skills in diagnosing ACL rupture.

Detection of the center of the hip joint in computer-assisted surgery: an evaluation study of the Surgetics algorithm.

OBJECTIVE: The aim of this paper is to assess the accuracy of an algorithm implemented by PRAXIM in the SURGETICS navigation station for detection of the hip center. This study will assess the robustness and accuracy of the algorithm in various clinical situations such as those involving non-sphericity of the femoral head, motion of the pelvis during hip center detection, and restricted range of motion. MATERIALS AND METHODS: The localization of the hip center, based on kinematics, relies on the recording of n successive positions of the femoral rigid body in the localizer reference system during a passive circumduction motion of the hip joint. Therefore, the shape of the clouds of points acquired may vary from one acquisition to the next. To allow a comprehensive study of the consequences of these variations for hip center detection, we developed a simulator to generate numerous clouds of points. Results given subsequently for each test are the values of the difference between the femoral mechanical axis computed with C(c), the computed hip center, and the same axis computed with C(o), the reference hip center. RESULTS: Test 1: Sensitivity to noise. The errors ranged from 3.33 E - 12 (SD 3.29E - 12) for a noise of 0 mm to 8.18E - 1 (SD - 7.05E - 1) for a noise of 15 mm. Test 2: Sensitivity to the shape of the acquisition motion. All trajectories gave an error < 1 degrees . Test 3: Sensitivity to restricted range of motion. No value > 1 degrees was found during this test. Test 4: Sensitivity to the distance between two points of the cloud. No value > 0.5 degrees was found during this test. Test 5: Sensitivity to the number of points included in the cloud. No value > 1 degrees was found during this test. CONCLUSIONS: The Surgetics algorithm is robust to noise, can compensate for pelvic motion, and can be used even in the case of restricted range of motion.