Patricia Thoreux

Declining Incidence of Catastrophic Cervical Spine Injuries in French Rugby 1996–2006

Purpose To investigate the incidence and the risk factors of catastrophic cervical spine injuries in French rugby. Study Design Descriptive epidemiology study. Methods The patients included had cervical spine injuries causing neurological disorder classified from the ASIA scale, grade A to D. A retrospective review of all cases that occurred between the 1996-1997 and the 2005-2006 seasons was made. Circumstances of the injuries and of the clinical outcome were collected by interview. Results There were 37 cases of catastrophic cervical spine injuries in French rugby for the last 10 years. The incidence of the cervical spine injuries decreased during this period. The rates of injury were 2.1 per 100 000 players per year during the 1996-1997 season and 1.4 during the 2005-2006 season (P <. 01). The scrum was a major cause of injury, accounting for 51.3% (19/37). The forwards represented 89.2% (33/37) of the injured players. The hookers were involved in 37.8% (14/37) of the cases. The measures of prevention with the modification of the rules of scrum and the creation of a medical certificate required for players to play in the front row must have been successful. Conclusion The incidence of disabling cervical spine injuries in French rugby has decreased for the last 10 years, which is linked to the decreasing incidence of injuries in the scrum. This epidemiological study shows the effectiveness of the preventive measures on cervical spine injuries in French rugby players. A national register of catastrophic cervical spine injuries extends our epidemiological observations.

Three-Dimensional Analysis of the Cervical Spine Kinematics: Effect of Age and Gender in Healthy Subjects

Study Design. A three-dimensional (3D) analysis of the cervical spine kinematics in vivo about a large asymptomatic database in order to evaluate the impact of age and gender on the necks performances. Objective. To investigate the effect of age and gender on kinematical parameters of the cervical spine, specifically quantitative parameters concerning coupled movements and proprioception, using the infra-red POLARIS measurement system. Summary of Background Data. Cervical spine kinematics has been investigated in vivo by numerous authors using various devices. However, few is known about the influence of gender and age on the 3D cervical biomechanics, specifically regarding coupled movements and proprioceptive abilities. Methods. A total of 140 asymptomatic volunteers (70 men and 70 women) aged 20 to 93 years old were enrolled. The noninvasive infrared system Polaris was used to quantify the 3D range of motion (ROM) of cervical spine and to evaluate proprioceptive abilities. For validating the protocol in terms of reproducibility, 12 volunteers were tested 3 times by 2 independent operators. Results. The standard error of measurement for the maximal ROM in the 3 space planes was 5%. Gender had no significant influence on the 3D cervical ROM, except for the “70–79 years old” group. Age had a significant influence on all main movements showing 0.55° to 0.79° magnitude decrease per decade. Age and gender had no significant influence on coupled movements. “Head-to-Target” proprioception was significantly affected by the age only in the horizontal plane. Conclusion. A data base for cervical ROM, pattern of motion, and proprioceptive capability was established in population of 140 healthy subjects of various age and gender. Significant age-related decrease in ROM and proprioceptive abilities were observed in this study. Coupled movements did not vary with gender or age; however, their role in the cervical performance increased with age since main movements were limited.

Three-dimensional reconstruction of the lower limb from biplanar calibrated radiographs

Three-dimensional (3D) reconstruction of lower limbs is essential for surgical planning and clinical outcome evaluation. 3D reconstruction from biplanar calibrated radiographs may be an alternative to irradiation issues of CT-scan. A previous study proposed a two-step reconstruction method based on parametric models and statistical inferences leading to a fast Initial Solution (IS) followed by manual adjustments. This study aims to improve the IS using a new 3D database, a novel parametric model of the tibia and a different regression approach. The IS was evaluated in terms of shape accuracy on 9 lower limbs and reproducibility of clinical measurements on 22 lower limbs. Reconstruction time was also evaluated. Comparison to the previous method showed an improvement of the IS in terms of shape accuracy (1.3 vs. 1.6 and 2 mm respectively for both femur and tibia) and reproducibility of clinical measurements (i.e. 3.1° vs. 8.3° for neck-shaft-angle; 4.2° and 5° vs. 5° and 6° for tibial and femoral torsion respectively). The proposed approach constitutes a considerable step towards an automatic 3D reconstruction of lower limb.

Tibio-femoral joint constraints for bone pose estimation during movement using multi-body optimization

When using skin markers and stereophotogrammetry for movement analysis, bone pose estimation may be performed using multi-body optimization with the intent of reducing the effect of soft tissue artefacts. When the joint of interest is the knee, improvement of this approach requires defining subject-specific relevant kinematic constraints. The aim of this work was to provide these constraints in the form of plausible values for the distances between origin and insertion of the main ligaments (ligament lengths), during loaded healthy knee flexion, taking into account the indeterminacies associated with landmark identification during anatomical calibration. Ligament attachment sites were identified through virtual palpation on digital bone templates. Attachments sites were estimated for six knee specimens by matching the femur and tibia templates to low-dose stereoradiography images. Movement data were obtained using stereophotogrammetry and pin markers. Relevant ligament lengths for the anterior and posterior cruciate, lateral collateral, and deep and superficial bundles of the medial collateral ligaments (ACL, PCL, LCL, MCLdeep, MCLsup) were calculated. The effect of landmark identification variability was evaluated performing a Monte Carlo simulation on the coordinates of the origin-insertion centroids. The ACL and LCL lengths were found to decrease, and the MCLdeep length to increase significantly during flexion, while variations in PCL and MCLsup length was concealed by the experimental indeterminacy. An analytical model is given that provides subject-specific plausible ligament length variations as functions of the knee flexion angle and that can be incorporated in a multi-body optimization procedure.

Spinal Surgery and Ophthalmic Complications: A French Survey With Review of 17 Cases

Objectives Ocular complications after spine surgery are incompletely understood and are not as rare as implied by recent publications. In 13 out of 15 published case reports, ocular complications are attributed mainly to compression. But in 66 cases reported in 4 series in the literature, compression seems to play a role in less than 10 cases. However, 3 out of the 4 series lack sufficient detail to support this mechanism clearly. Our objectives were to identify the mechanisms and specific risk factors associated with this devastating complication, to help in prevention. Methods A 2-page survey was sent to all French orthopedic centers specializing in spine surgery (28 centers) requesting information regarding any patients who had experienced visual deficits after spine surgery. Respondents were asked to identify presence of commonly cited preoperative risk factors, including ophthalmologic diagnosis and local signs (eyelid or conjunctival edema, periorbital numbness, or paresthesia) and intraoperative risks, such as positioning of the head, to clarify the possible mechanisms. Seventeen patients were thus included. Results Two main mechanisms were identified. First, ocular compression (9 cases) characterized by a unilateral definitive blindness with local signs due to a central retinal artery occlusion. Second, internal carotid thromboembolism (4 cases) associated with head rotation toward the ipsilateral side, causing an ischemic optic neuropathy with a unilateral partial and potentially regressive visual loss. Conclusions The authors propose 2 preventive measures: modification of horseshoe-shaped headrest and precautions with lateral rotation of the head in patients with carotid atheroma.

A method for the field assessment of rolling resistance properties of manual wheelchairs

This article presents an examination and validation of a method to measure the field deceleration of a manual wheelchair (MWC) and to calculate the rolling resistances properties of the front and rear wheels. This method was based on the measurements of the MWC deceleration for various load settings from a 3D accelerometer. A mechanical model of MWC deceleration was developed which allowed computing the rolling resistance factors of front and rear wheels on a tested surface. Four deceleration sets were conducted on two paths on the same ground to test the repeatability. Two other deceleration sets were conducted using different load settings to compute the rolling resistance parameters (RPs). The theoretical decelerations of three load settings were computed and compared with the measured decelerations. The results showed good repeatability (variations of measures represented 6–11% of the nominal values) and no statistical difference between the path results. The rolling RPs were computed and their confidence intervals were assessed. For the last three sets, no significant difference was found between the theoretical and measured decelerations. This method can determine the specific rolling resistance properties of the wheels of a MWC, and be employed to establish a catalogue of the rolling resistance properties of wheels on various surfaces.

Sequential 3D analysis of patellofemoral kinematics from biplanar x-rays: In vitro validation protocol

BACKGROUND Developing criteria for assessing patellofemoral kinematics is crucial to understand, evaluate, and monitor patellofemoral function. The objective of this study was to assess a sequential 3D analysis method based on biplanar radiographs, using an in vitro protocol. HYPOTHESIS Biplanar radiography combined with novel 3D reconstruction methods provides a reliable evaluation of patellofemoral function, without previous imaging. MATERIAL AND METHODS Eight cadaver specimens were studied during knee flexion cycles from 0° to 60° induced by an in vitro simulator. The protocol was validated by investigating sequential and continuous motion using an optoelectronic system, evaluating measurement accuracy and reproducibility using metallic beads embedded in the patella, and comparing the 3D patellar geometry to computed tomography (CT) images. RESULTS The differences in position between the sequential and continuous kinematic analyses were less than 1mm and 1°. The protocol proved reliable for tracking several components of knee movements, including patellar translations, flexion, and tilt. In this analysis, uncertainty was less than 2 mm for translations and less than 3° for rotations, except rotation in the coronal plane. For patellar tilt, uncertainty was 5°. Mean difference in geometry was 0.49 mm. DISCUSSION Sequential analysis results are consistent with continuous kinematics. This analysis method provides patellar position parameters without requiring previous CT or magnetic resonance imaging. A clinical study may deserve consideration to identify patellofemoral kinematic profiles and position criteria in vivo. LEVEL OF EVIDENCE IV, experimental study.

Diagnostic préopératoire des anses de seau méniscales : valeur des critères cliniques, arthro-TDM et IRM: À propos d’une série de 33 cas confirmés par arthroscopie

Resume L’objectif de cette etude etait d’analyser la pertinence des signes cliniques et l’apport des nouvelles modalites d’imagerie en coupe (arthro-TDM et IRM) pour le diagnostic preoperatoire d’un type de lesions meniscales longitudinales dites en anse de seau. Il s’agit d’une serie retrospective de 33 lesions meniscales en anse de seau confirmees arthroscopiquement, ayant beneficie d’un bilan preoperatoire comportant une arthrographie et/ou un arthro-TDM et/ou une IRM. Les examens ont ete relus par 2 radiologues seniors en consensus. Les principaux signes cliniques recherches etaient des antecedents de blocage typique et l’existence d’un flessum preoperatoire. Les signes radiologiques etudies correspondaient a la visualisation du fragment deplace, en coupe coronale (fragment dans l’echancrure) ou sagittale (megacorne anterieure, double LCP, signe du serpent). Les antecedents de blocage typique etaient retrouves 14 fois et un flessum 15 fois. Seuls 10 patients presentaient l’association evocatrice « blocage + flessum ». Le diagnostic positif de lesion meniscale en anse de seau etait porte en IRM (13/15), en arthro-TDM (6/7) et en arthrographie (10/24), soit une sensibilite equivalente pour les 2 techniques d’imagerie en coupe. Le signe du fragment dans l’echancrure en coupe coronale est un signe constant. Le signe du double LCP est un signe sensible pour les lesions du menisque medial et pour les lesions du menisque lateral en cas de rupture associee du LCA. 9 patients avaient eu plusieurs examens (n = 2 ou 3) et aucun faux negatif n’etait retrouve dans ce groupe. Dans 9 cas, le diagnostic d’anse de seau n’avait pas ete porte (Arthrographie : n = 7 ; IRM : n = 2). Dans ces cas, on peut incriminer l’etroitesse du fragment meniscal et parfois le delai entre le bilan et l’arthroscopie.PURPOSE OF THE STUDY It is important for both the patient and the surgeon to determine whether a meniscal lesion can be repaired before undertaking surgery. The purpose of this study was to examine the pertinence of clinical signs and determine the value of imaging findings for the preoperative diagnosis of bucket-handle meniscal tears. This preliminary study was conducted before undertaking an analysis of preoperative criteria of reparability in a homogeneous group of meniscal lesions. MATERIAL AND METHODS This retrospective series included 33 arthroscopically-proven bucket-handle meniscal tears in patients who underwent arthrography and/or arthroscan and/or MRI preoperatively. The images were reviewed by two senior radiologists who established a consensus diagnosis. Clinically, the type of blockage and the presence of permanent flexion before surgery were noted. The following items were noted on the imaging results: fragment displacement (fragment in the notch on the coronal slice) anterior megahorn, double PCL, and serpent sign on the sagittal slice. Longitudinal, transversal extension and position of the bucket-handle were noted. We searched for correlations with the intraoperative findings. RESULTS Fourteen patients had a history of knee blocking and 15 had permanent flexion before surgery. Only 10 patients had the typical association of blocking and flexion. Certain diagnosis of bucket-handle meniscal tear was provided by MRI (13/15), arthroscan (6/7), and arthrography (10/24) giving an equivalent sensitivity for the two slice imaging techniques. The sign of a fragment in the notch on the coronal slice was a constant finding. The double PCL sign was sensitive for medial meniscal tears and for lateral meniscal tears with associated ACL tears. The diagnosis was successfully established in all 9 patients who underwent several explorations (2 or 3). Buckle-handle meniscal tear was not identified in 9 patients (arthrography 7, MRI 2). DISCUSSION Our findings demonstrate that the preoperative diagnosis of bucket-handle meniscal tears cannot be properly established on clinical criteria of typical blocking and/or permanent flexion. They confirm that arthrography is not contributive to diagnosis and that the absence of a slice image is detrimental to diagnosis. The sensitivity of the two slice imaging methods was similar. The key sign was the presence of a fragment in the notch on the coronal slice; in the three cases where this sign was absent, the reason was found to be the small size of the displaced fragment (resolution limit) and time between imaging and arthroscopy. The characteristic features of the bucket-handle lesions observed in this series are exactly the same as reported in earlier reports but to our knowledge provide the first data on comparative performance of arthroscan and MRI. CONCLUSION The noninvasive nature of MRI and the possibility of assessing the meniscal wall and the quality of the meniscal tissue make MRI the exploration of choice for preoperative assessment of meniscal tears.

A new method for the evaluation of the end-to-end distance of the knee ligaments and popliteal complex during passive knee flexion

BACKGROUND Accurate knowledge about the length variation of the knee ligaments (ACL, PCL, MCL and LCL) and the popliteal complex during knee flexion/extension is essential for modelling and clinical applications. The aim of the present study is to provide this information by using an original technique able to faithfully reproduce the continuous passive knee flexion-extension kinematics and to reliably identify each ligament/tendon attachment site. METHODS Twelve lower limbs (femur, tibia, fibula, patella) were tested and set in motion (0-120°) using an ad hoc rig. Tibio-femoral kinematics was obtained using an optoelectronic system. A 3D digital model of each bone was obtained using low-dosage stereoradiography. Knee specimens were dissected and the insertion of each ligament and popliteal complex were marked with radio opaque paint. ACL, PCL and MCL were separated into two bundles. Bone epiphyses were CT-scanned to obtain a digital model of each ligament insertion. Bones and attachment site models were registered and the end-to-end distance variation of each ligament/tendon was computed over knee flexion. RESULTS A tibial internal rotation of 18°±4° with respect to the femur was observed. The different bundles of the ACL, MCL and LCL shortened, whereas all bundles of the PCL lengthened. The popliteal complex was found to shorten until 30° of knee flexion and then to lengthen. CONCLUSION The end-to-end distance variation of the knee ligaments and popliteal complex can be estimated during knee flexion using a robust and reliable method based on marking the ligaments/tendon insertions with radiopaque paint. LEVEL OF EVIDENCE Level IV.

Assessing the accuracy and precision of manual registration of both femur and tibia using EOS imaging system with multiple views

The EOS imaging system produces two simultaneous X-rays of a subject. Both views are used for the generation of a subject-specific 3D skeletal model. This model then allows to obtain quantitative parameters concerning the morphology and the positioning of bones. Furthermore, thanks to the low dose of the EOS imaging, it is possible to take several stereoradiographies of the same subjects in order to study different positions of the femoro-patellar joint (Dagneaux et al. 2014) or to analyze different positions of the subjects. Also, it can be a way to compare tibia and femur relative positions without and with an orthotic device such as a brace for example. For that, the 3D model, obtained from the reference standing position, is registered across the different pairs of X-rays for the other positions. The goals of this study are 1/ to evaluate the reproducibility of the registration of both in vitro and in vivo and 2/ to a o assess the accuracy of this manual method using in vitro data.