Anatomical risk evaluation of iatrogenic injury to the infrapatellar branch of the saphenous nerve during medial meniscus arthroscopic surgery.

PURPOSE: To determine the relationship of the medial meniscus with the infrapatellar branches of the saphenous nerve, the primary goal is to define and characterize different risk areas for these nerves during medial meniscus surgery. METHODS: After dissecting 20 embalmed cadaver knees, we defined 7 readily identifiable anatomical landmarks. For each knee, we recorded 2 morphological criteria and 16 measurements. RESULTS: The most common anatomical course is a main trunk that is 8 mm anterior to the tuberculum adductorium and 60 mm posterior to the midpoint of the medial patellar margin. It has two main infrapatellar branches. The nerve division is 23 mm above the joint line. The path is oblique with an angle of 55.5°. The anterior meniscal landmark is 24 mm from the upper branch and 42.5 mm from the lower branch. The posterior meniscal landmark is 55 mm from the upper branch and 38 mm from the lower branch. CONCLUSIONS: We defined a common anatomical course for the saphenous nerve and its infrapatellar branches. Then, three different areas were defined at risk for iatrogenic nerve injuries during medial meniscus.

Morphological analysis of the glenoid version in the axial plane according to age.

PURPOSE: Total shoulder arthroplasty planning requires a preoperative assessment of the glenoid version. This study aimed to determine the morphologic profile of the glenoid cavity and our null hypothesis was that age may affect the spiraling aspect. METHOD: 114 CT arthrographies of patients from 15 to 78 years old were included. Four groups were defined according to age: 15-29, 30-44, 45-59 years old, and over 60. The version of the glenoid was measured in the axial plane according to the most common method: a line is drawn between the osseous anterior and posterior margins of the glenoid and the version corresponds to the angle between this line and the transverse axis of the glenoid. The transverse axis of the scapula is determined by a line drawn from the center of the glenoid fossa to the medial border of the scapula. The axial plane (perpendicular to the supero-inferior axis of the glenoid cavity) was defined by multiplanar reconstruction. The measurements were performed at three regions of interest: the level of the coracoid process (region A), the level of the notch on the anterior border of the glenoid (region B), and the region of the greater antero-posterior diameter (region C). RESULTS: 96 % of the glenoid cavities included were retroverted. The mean version in region A was 11.9° (0-24.3, S-D 5.2), in region B 6.85° (-5.2 to 12.1, S-D 4.13) and in region C 4.04° (-7.7 to 11.1, S-D 4.04). The difference between the mean version of region A and region B was 5.02° and the difference between the mean version of the region B and the mean version of the region C was 2.81°. When considering the rate of change of the mean version between two adjacent regions, no difference was observed between the four groups of age. DISCUSSION: The analysis showed the importance of the axial reconstruction plan chosen to allow interpretable and reproducible measures. A decreasing version of the glenoid superior-to-inferior was observed, presenting a spiraling twist as described in previous studies. The profile of variation does not change in the four groups of patients included. The reconstruction of an articular surface as close to the anatomy as possible would also participate in establishing the muscular balance and the constraints on implants. Up to now, implants do not take into account this cranio-caudal twisting.

A new partial temporal bone of a juvenile hominin from the site of Kromdraai B (South Africa).

The site of Kromdraai B (KB) (Gauteng, South Africa) has yielded a minimum number of nine hominins including the type specimen of Paranthropus robustus (TM 1517), the only partial skeleton of this species known to date. Four of these individuals are juveniles, one is a subadult and four are young adults. They all occur with a macrofaunal assemblage spread across the succession of at least two time periods that occurred in South Africa approximately two million years ago. Here we report on an additional, newly discovered petrous temporal bone of a juvenile hominin, KB 6067. Following the description of KB 6067, we assess its affinities with Australopithecus africanus, P. robustus and early Homo. We discuss its developmental age and consider its association with other juvenile hominin specimens found at Kromdraai B. KB 6067 probably did not reach five years of age and in bony labyrinth morphology it is close to P. robustus, but also to StW 53, a specimen with uncertain affinities. However, its cochlear and oval window size are closer to some hominin specimens from Sterkfontein Member 4 and if KB 6067 is indeed P. robustus this may represent a condition that is evolutionarily less derived than that shown by TM 1517 and other conspecifics sampled so far. The ongoing fieldwork at KB, as well as the petrography and geochemistry of its deposits, will help to determine when the various KB breccias accumulated, and how time may be an important factor underlying the variation seen among KB 6067 and the rest of the fossil hominin sample from this site.

Investigation of the human bridging veins structure using optical microscopy.

In this paper, we investigated the brain-sinus junction and especially the bridging veins linking these two organs. Two types of optical microscopy were used: conventional optical microscopy and digital microscopy. We used thin histological sections prepared from a human brain, and stained with Masson's trichrome, hemalun and orcein. Finally we observed the path of the bridging vein inside the brain-skull interface. At smaller scales, wavy collagen fiber bundles were found and characterized inside the vein walls. Taking into account the orientations of the different sections with reference to frontal planes, we found that the bridging vein has a very complex geometry, which increases the difficulty to determine fiber orientations in its walls. Nevertheless, we found that collagen fiber bundles are mainly circumferentially oriented in the superior sagittal sinus walls. In this paper, we were able to characterize precisely the path of the bridging vein from the brain to the sinus, with different magnifications.

Anatomic attachment of the ACL. Comparison between radiological and CT analysis.

PURPOSE: The following hypothesis was tested: the location of the tibial and femoral anterior cruciate ligament (ACL) attachments will differ according to the measurement technique (plain radiographs or CT-scan) in relation to the anatomic frame of reference. METHODS: 10 gross specimens were studied. The location of metallic reference pins implanted around the tibial and femoral ACL attachments was recorded with reference to the bone contours with a caliper on the anatomic preparation, with standard plain AP and lateral radiographs and with a CT-scan. Results were compared with appropriate statistical tests at a 0.05 level of significance. RESULTS: The mean ratio between the antero-posterior tibia measurement and the center of the ACL tibial attachment varied from 50 to 52%. The mean ratio between the medio-lateral tibia measurement and the center of the ACL tibial attachment varied from 49 to 51%. The mean ratio between the antero-posterior femur measurement and the center of the ACL femoral attachment varied from 74 to 80%. The results were significantly different between the three techniques (respectively P = 0.003, P = 0.02 and P = 0.045). DISCUSSION: The paired differences were small (3% at the tibia, 6% at the femur). There was a strong correlation and a good agreement between the three techniques. It is likely that the small differences on the tibia have few, if any, clinical relevance. CONCLUSION: Both radiographic and CT-scan measurement techniques used during the present study have the potential to be used as quality control after ACL replacement. LEVEL OF EVIDENCE: Diagnostic study-investigating a diagnostic test. Development of diagnostic criteria in a consecutive series of patients and a universally applied "gold" standard, Level II.

Digastric olecranon osteotomy: feasibility study of a new approach to the elbow.

PURPOSE: None of the multiple posterior approaches to the elbow simultaneously satisfies the following three properties: good articular surface exposure, attention to the extensor apparatus continuity and olecranon vascularization. This study aims to describe a new approach to the elbow: digastric olecranon osteotomy. METHODS: Nine anatomical subjects were prepared. One-third underwent intra-articular digastric osteotomy, one-third extra-articular osteotomy and one-third a vascularization study using arteriography. RESULTS: Digastric olecranon osteotomy, notably intra-articular, offered excellent articular exposure. After restoration, digastric stability was excellent. Olecranon vascularization was preserved using the two variations of digastric olecranon osteotomy. CONCLUSION: Digastric olecranon osteotomy preserves the principal vascular supply of the olecranon and the continuity of the extensor apparatus. Articular surface exposure is excellent, and the natural coaptation of the digastric enables immediate mobilization without any theoretical risk of deconstruction.

Biomechanics of open Bankart and coracoid abutment procedures in a human cadaveric shoulder model.

The specific aims of this experiment were (1) to develop a clinically relevant model of anteroinferior shoulder dislocation in the apprehension position to compare the biomechanics of the intact anterior capsuloligamentous structures, and (2) to evaluate the initial strength of an open Bankart and of a coracoid abutment procedure. Fifteen shoulders from deceased donors were used. For the intact shoulders, mean peak load was 486 N, and stiffness was 26,7 N/mm. For the Bankart repair, the mean peak load was 264 N, and mean stiffness was 14.1 N/mm. Transosseous repairs failed by suture pullout through soft tissues. For the coracoid abutment repair, the mean peak load was 607 N and stiffness was 25.57 N/mm. This study reveals that the biomechanical performance of the Bankart and coracoid abutment repairs fails to reproduce the properties of the natural intact state.

Development and biomechanical testing of a new osteosynthesis plate (TCP) designed to stabilize mandibular condyle fractures.

INTRODUCTION: In this paper, the different steps of development and experimental validation of a new type of three-dimensional (3-D) trapezoidal osteosynthesis plate (Modus TCP 2.0, Medartis, Basel, Switzerland) is described. These plates have been designed to stabilize sub-condylar and condylar neck fractures of the mandible. MATERIAL AND METHODS: In order to apply the principles of functionally stable osteosynthesis to the mandibular condyle, i.e. to put the plate as close as possible to the tensile strain lines occurring during function, two new 4- and 9-hole 3-D trapezoidal plates were designed. Tests were conducted on fresh human mandibles before and after osteosynthesis of a standardised unilateral sub-condylar 'fracture', and a static biting exercise between the ipsilateral first molars was reproduced on a test bench. The resulting condylar fragment displacement in the sagittal plane was measured and the alterations of the condylar tensile strain lines induced by the osteosynthesis were investigated by using photoelastic strain tests. RESULTS: None of the plates broke. No macroscopic condylar displacement was noted when assessing the quality of the primary stabilization. Strain analysis showed the ability of these 3-D plates to transmit physiological strains across the fracture line and the absence of potentially damaging strains around the plate. DISCUSSION: These results were accredited to the 3-D and trapezoidal features of the plates. CONCLUSION: The Modus TCP plates experimentally fulfil the principles of functionally stable osteosynthesis in the condylar region and are able to resist physiological strains.

Photoelastic analysis of bone deformation in the region of the mandibular condyle during mastication.

INTRODUCTION: The purpose of this experimental study was to demonstrate the stress patterns arising in the region of the mandibular condyle during mastication. MATERIAL AND METHOD: Stress analysis was performed using reflection photoelasticity to demonstrate deformation occurring on the surface of the mandible. The rami of three fresh dentate human mandibles were coated with a shell of photoelastic resin. Using a novel loading device, these mandibles were then subjected to external forces (muscular traction, resultant mandibular forces and intra-articular reaction force) reproducing a unilateral biting task between the first right molars. Deformations were measured from the working side. RESULTS: The trace of isostatic lines from the isoclinic fringes revealed major differences in stress distributions between the three mandibles. These differences were attributed to differences in shape between the three mandibles. Conversely, we consistently found compressive stress patterns along the posterior border of the ramus and tensile stress patterns along the anterior border of the ramus and in the zone situated below the siqmoid notch. CONCLUSION: These findings suggest that during this particular task, the mandible is subjected to sagittal forces which tend to straighten the mandibular angle. This implies that new concepts are needed for the positioning of osteosynthesis plates in the condylar region, close to the tensile strain lines, as has been recommended also for other parts of the mandible when applying semi-rigid internal fixation.

Comparison of the accuracy of 3-dimensional cone-beam computed tomography and micro-computed tomography reconstructions by using different voxel sizes.

INTRODUCTION: Cone-beam computed tomography (CBCT) data are, in principle, metrically exact. However, clinicians need to consider the precision of measurements of dental morphology as well as other hard tissue structures. CBCT spatial resolution, and thus image reconstruction quality, is restricted by the acquisition voxel size. The aim of this study was to assess geometric discrepancies among 3-dimensional CBCT reconstructions relative to the micro-CT reference. METHODS: A total of 37 permanent teeth from 9 mandibles were scanned with CBCT 9500 and 9000 3D and micro-CT. After semiautomatic segmentation, reconstructions were obtained from CBCT acquisitions (voxel sizes 76, 200, and 300 µm) and from micro-CT (voxel size 41 µm). All reconstructions were positioned in the same plane by image registration. The topography of the geometric discrepancies was displayed by using a color map allowing the maximum differences to be located. RESULTS: The maximum differences were mainly found at the cervical margins and on the cusp tips or incisal edges. Geometric reconstruction discrepancies were significant at 300-µm resolution (P = .01, Wilcoxon test). CONCLUSIONS: To study hard tissue morphology, CBCT acquisitions require voxel sizes smaller than 300 µm. This experimental study will have to be complemented by studies in vivo that consider the conditions of clinical practice.

Are there age induced morphologic variations of the superior glenoid labrum? About 100 shoulder arthroscopies.

Different anterosuperior aspects of the glenoid labrum have already been described and are thought to be normal anatomical variations. The goals of this study were first to characterize these anterosuperior labral morphologies and then to analyze their variations in function of the patients' age. One hundred shoulder arthroscopies were recorded to study the macroscopic characteristics of the anterosuperior labrum of the glenohumeral joint and its relationships with the proximal insertion of the tendon of the long head of the biceps. Then, patients were divided into two groups in function of their age (below and over 30 years old). Morphological modifications of the labrum were found in function of the age of the patient with an increase of the nonpathologic "mobile labrum" type after 30 years (P=0.0423). Therefore a mobile and loosely attached superior labrum should not always be considered as abnormal, especially in case of patient older than 30 years.