Morfología y Fisiopatología del Fibrocartílago de la ATM. Revisión sistemática / Morphology and Pathophysiology of the TMJ Fibrocartilage. Systemic review

RESUMEN: El objetivo: del presente estudio fue efectuar una revisión actualizada de la morfología, fisiopatología y aspectos moleculares de la capa fibrocartilaginosa de las ATM en humanos. Método: se realizó búsqueda electrónica y manual con los términos MeSH "TMJ" y "fibrocartilage", sin límite de fecha o idioma. Los desenlaces definidos fueron: morfología del fibrocartílago, fisiopatología del fibrocartílago articular, modeladores moleculares del fibrocartílago y deterioro del fibrocartílago. Resultados: Se identificaron 1.071 títulos de artículos que después de las exclusiones, fueron seleccionados 16 a texto completo para la revisión. El fibrocartílago (FC) que cubre las superficies de las ATM es un tejido crítico en el establecimiento y la tasa de progresión de las alteraciones óseas degenerativas, clínicamente sus discontinuidades se asocian a patologías que provocan dolor, ruidos y limitación funcional. Conclusiones: A pesar de la diversidad metodológica, heterogeneidad de objetivos y diferentes características de los estudios incluidos en la revisión, el fibrocartílago de la ATM, como tejido avascular, determina fisiología de baja capacidad reparativa y mayor frecuencia de patología del FC en mujeres en edad fértil, asociado a receptores hormonales. La fisiopatología muestra reacciones inmunitarias que incrementan la acción de MMPs, interleucinas y FNTα, responsables de la degradación de la matriz extracelular, destrucción celular y morfológica del fibrocartílago, que conducen a sintomatología inflamatoria y degenerativa de pacientes que presentan artralgias y sinovitis en las ATM.

ABSTRACT: The aim: of the present study was to carry out an updated review of the morphology, physiopathology and molecular aspects of the TMJ fibrocartilage in humans. Method: electronic/manual search was performed with the MeSH terms "TMJ" and "fibrocartilage", with no date or language limit. The defined outcomes were: morphology of the fibrocartilage, physiopathology of the articular fibrocartilage, fibrocartilage molecular modelers and fibrocartilage deterioration. Results: 1071 articles were identified and after exclusions, 16 full-texts were selected for review. The fibrocartilage (FC) that covers the surfaces of the TMJ is a critical tissue in the establishment and progression rate of degenerative bone diseases; clinically, its discontinuities are associated with pain, noise and functional limitation. Conclusions: In spite of the methodological diversity, heterogeneity of objectives and different characteristics of the patients included in the review, TMJ fibrocartilage, as avascular tissue, determines a physiology of low reparative capacity, observed with greater frequency of FC damage in women of fertile age, associated with a greater amount of hormonal receptors. The physiopathology shows that the immune reactions increase some MMPs, interleukins and FNTα, which are linked to the degradation of the extracellular matrix, FC cellular and morphological destruction and define the inflammatory and degenerative symptomatology of patients who present TMJ arthralgia´s and synovitis.

Pectoralis major tendon and enthesis: anatomic, magnetic resonance imaging, ultrasonographic, and histologic investigation.

BACKGROUND: This study evaluates the pectoralis major (PM) tendon humeral insertion, using imaging and histologic assessment in cadaveric specimens. Current descriptions of the pectoralis major tendon depict a bilaminar enthesis, and clarification of the anatomy is important for diagnostic and surgical considerations. MATERIALS AND METHODS: Fourteen fresh-frozen whole upper extremity specimens were used in this study. Magnetic resonance (MRI) and ultrasonographic (US) imaging of the PM muscles, tendons, and entheses were performed, followed by anatomic dissection and inspection. Morphology of the lateral tendon and entheses were evaluated, focused on the presence of layers. In 11 specimens, the lateral 3 cm of the PM tendon was carefully dissected from the footprint, whereas in 3 specimens, the tendon and humeral insertion were preserved and removed en bloc. Histology was performed in axial slabs along the medial-lateral length of the tendon and also evaluated for the presence of layers. RESULTS: The superior-inferior and medial-lateral lengths of the PM footprint were 75 ± 9 mm and 7 ± 1 mm respectively. In all specimens, the clavicular and sternal head muscles and tendons were identified, with the clavicular head tendon generally being shorter. The medial-lateral length of the clavicular head tendon measured 19 ± 8 mm superiorly and 9 ± 3 mm inferiorly. The medial-lateral length of the sternal head tendon measured 38 ± 8 superiorly and 41 ± 18 mm inferiorly. All specimens demonstrated a unilaminar, not bilaminar, enthesis with abundant fibrocartilage on histology. Three specimens demonstrated interspersed entheseal fat and loose connective tissue at the enthesis on MRI and histology. CONCLUSION: The PM tendon humeral insertion consists of a unilaminar fibrocartilaginous enthesis. US, MRI, and histology failed to identify true tendon layers at the enthesis. Delaminating injuries reported in the literature may originate from a location other than the enthesis.

Functional Adaptation of the Fibrocartilage and Bony Trabeculae at the Attachment Sites of the Anterior Cruciate Ligament.

The direct insertion of an enthesis is composed of uncalcified fibrocartilage (FC) and calcified FC, believed to function as buffers for multidirectional forces applied to the ligament. This study was performed to investigate the relationship between the FC thickness and bony trabecular orientation of the anterior cruciate ligament (ACL) on both the femoral and tibial sides. Six cadavers were examined (age at death: 73-92 years). Both femoral and tibial insertions of the ACL were harvested and used to make 0.5 mm interval semi-serial sections. Microdigital images were taken and used to measure the maximum thickness of both the uncalcified FC and Calcified FC. Two-dimensional discrete Fourier analysis was also performed to determine the orientation angle and orientation intensity of bony trabeculae directly under the FC. The mean thicknesses of the uncalcified FC at the femoral and tibial insertions were 0.98 mm and 0.49 mm, respectively. The mean thicknesses of the calcified FC were 0.47 mm and 0.38 mm, respectively. There was a significant difference in the uncalcified FC thickness, but not in the calcified FC thickness. The bony trabeculae showed a prominent orientation parallel to the ACL fiber on both sides, but it was more intense on the tibial side than on the femoral side. The trabecular orientation was prominent in the proximal-posterior part of the femoral side and in the anteromedial part of the tibial side, suggesting that mechanical stress is greater in these parts. The dominant bony trabecular angle was 69.0° on the femoral side and 59.8° on the tibial side when the tidemark was set at 0°. These findings suggest that the femoral side receives multidirectional stresses, while relatively unidirectional stress is loaded on the tibial side. Furthermore, stress is considered to be greater in the proximal-posterior part of the femoral insertion and in the anteromedial part of the tibial insertion. At the time of ACL reconstruction, attention should be paid to assign a robust portion of the graft to the posterior part of the femoral insertion and anteromedial part of the tibial insertion. Clin. Anat., 33:988-996, 2020. © 2019 Wiley Periodicals, Inc.

An Anatomical Study of the Anterosuperior Capsular Attachment Site on the Acetabulum.

BACKGROUND: Despite the fact that many surgeons perform partial capsular detachment from the anterosuperior aspect of the acetabulum to correct acetabular deformities during hip arthroscopy, few studies have focused on whether these detachments influence hip joint stability. The aim of this study was to investigate the capsular attachment on the anterosuperior aspect of the acetabulum. We hypothesized that the attachment on the inferior aspect of the anterior inferior iliac spine (AIIS) is wide and fibrocartilaginous and might have a substantial role in hip joint stability. METHODS: Fifteen hips from 9 cadavers of Japanese donors were analyzed. Eleven hips were analyzed macroscopically, and the other 4 were analyzed histologically. In all specimens, the 3-dimensional morphology of the acetabulum and AIIS was examined using micro-computed tomography (micro-CT). RESULTS: Macroscopic analysis showed that the widths of the capsular attachments varied according to the location, and the attachment width on the inferior edge of the AIIS was significantly larger than that on the anterosuperior aspect of the acetabulum. Moreover, the capsular attachment on the inferior edge of the AIIS corresponded with the impression, which was identified by micro-CT. Histological analysis revealed that the hip joint capsule on the inferior edge of the AIIS attached to the acetabulum adjacent to the proximal margin of the labrum. In addition, the hip joint capsule attached to the inferior edge of the AIIS via the fibrocartilage. CONCLUSIONS: The capsular attachment on the inferior edge of the AIIS was characterized by an osseous impression, large attachment width, and distributed fibrocartilage. CLINICAL RELEVANCE: It appeared that the capsular attachment on the inferior edge of the AIIS was highly adaptive to mechanical stress, on the basis of its osseous impression, attachment width, and histological features. Anatomical knowledge of the capsular attachment on the inferior edge of the AIIS provides a better understanding of the pathological condition of hip joint instability.

Bone Surface Micro-Topography at Craniofacial Entheses: Insights on Osteogenic Adaptation at Muscle Insertions.

Macroscopic details of the bone-muscle interface are represented by a mosaic of calcified features inclusive of fossae, tuberosities, crests, and ridges. These features are in part of an adaptive osteogenic response to dissipate forces of localized mechanical loading. In an osteoarchaeological or paleontological context, these features are interpreted as "musculoskeletal stress markers" to infer habitual behaviors. Microscopic surveys of bone surface topography of the enthesis can reveal localized osteogenic topologies. These features illustrate the developmental mechanisms that produce these bony forms and contribute to an evidential basis to read these structures. Microscopic osteogenic topographies at sites of gnathic muscle attachments located in the craniofacial skeleton were explored in reference to extrapolated loading vectors in an ontogenetic series of craniofacial skeletons of the primate (Procolobus verus). Epoxy resin replicas of bone surfaces were made, and micro-topographical detail viewed with Scanning Electron Microscope. Osteoclastic bone remodeling was found at entheses associated with presumptive net tensile loading. Mineralized fibrocartilage was present at entheses, associated with presumptive net compressive loading. Collectively, these outcomes suggest that entheses develop through adaptive osteogenic activity in response to differential vectors of local mechanical loading. However, the presence of mineralized fibrocartilage also suggests that proliferative cartilage has a role in the development of bone eminences providing functional processes. This study concludes that the vector of muscle loading at entheses as well as proliferative fibrocartilage is influencing the form of bony eminences in the primate craniofacial skeleton defining functional and species defining morphologies. Anat Rec, 302:2140-2155, 2019. © 2019 American Association for Anatomy.

Tissue on the Transferred Coracoid Graft After Latarjet Procedure: Histological and Morphological Findings.

BACKGROUND: Anterior shoulder instability is a debilitating condition that can require stabilization via a Latarjet procedure. PURPOSE: The aim of this study was to characterize the histological composition of the articular-sided surface of the coracoid bone graft after Latarjet procedure. Specific features of cells isolated from the coracoid and graft tissues were assessed. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Tissue samples were harvested from 9 consecutive patients undergoing arthroscopic debridement and screw removal after arthroscopic or open Latarjet procedure. Tissues were processed histologically. In 2 patients, the samples were analyzed to assess specific cellular properties. RESULTS: Safranin O staining indicated that glenoid tissues contained variable amounts of glycosaminoglycan (GAG) and round chondrocytic cells mainly organized in clusters. Graft tissues contained less GAG and were more cellular but were not organized in clusters and had variable morphological features. An association appeared to exist between the cartilage quality of glenoid tissues and that of the graft tissues. Cells isolated from glenoid and graft tissues exhibited similar proliferation capacity. CONCLUSION: The results of our analysis show that cells located at the articular-sided surface of transferred coracoid grafts demonstrate fibrocartilaginous properties and may have the capacity for chondral proliferation. Further studies are needed to confirm this observation and future application.

Is Bone Elevation in Hand Muscle Attachments Associated with Biomechanical Stress? A Histological Approach to an Anthropological Question.

In anthropological sciences, muscle attachments are typically utilized for reconstructing the physical activities of past human populations. This approach relies on the concept that entheseal bone morphology is influenced by cumulative biomechanical stress. A fundamental criterion for assessing the stage of entheseal change involves the proportion of elevated bone area. However, it is not yet clear if bone elevation is associated with biomechanical forces exerted during physical activity, while the histology of the entheses of the human hand, the least-bodyweight-bearing anatomical area, is not fully investigated. Multiple previous studies on entheses have concluded that the concentration of calcified fibrocartilage reflects the level of applied forces. On this basis, if hand entheseal surface elevation was associated with the level of biomechanical stress, then a greater amount of calcified fibrocartilage would be expected in entheses' central and more projecting bone areas. More importantly, individual entheses with a greater proportion of elevated bone areas would present a higher total concentration of calcified fibrocartilage. To test these hypotheses, this pilot study conducted a histological quantitative analysis on two thumb entheses of four fully-documented body donors. Across individuals, all central entheseal regions presented greater calcified fibrocartilage, while the entheses showing additional bone elevation in their marginal areas comprised substantially higher total values. The observations of this small-scale pilot study support the concept that interindividual differences in entheseal bone morphology are related to varying levels of biomechanical loading. Furthermore, they encourage future research to compile larger sample sizes, for comparing individuals with distinct lifelong activities. Anat Rec, 302:1093-1103, 2019. © 2018 Wiley Periodicals, Inc.

Revisiting the Anterior Glenoid: An Analysis of the Calcified Cartilage Layer, Capsulolabral Complex, and Glenoid Bone Density.

PURPOSE: In this cadaveric study, we aim to define the basic anatomy of the anterior glenoid with attention to the relationships of calcified cartilage, capsulolabral complex, and osseous morphology of the anterior glenoid. METHODS: Seventeen cadaveric glenoid specimens (14 male, 3 female, mean age 53.9 ± 10) were imaged with micro-computed tomography (CT) and embedded in poly-methyl-methacrylate. Specimens were included for final analysis only if the entire glenoid articular cartilage, labrum, capsule, and biceps insertion were pristine and without evidence of injury, degeneration, or damage during the preparation process. Group 1 members (n = 9) were axially sectioned through 3 to 9 o'clock and 4 to 8 o'clock; group 2 members (n = 8) were radially sectioned through 3, 4, 5, and 9 o'clock. A scanning electron microscope (SEM) analysis quantified the percentage of bone within a 5 × 2.5 mm region at the glenoid rim. Micro-CT, SEM, and light microscopy evaluated the capsulolabral complex and calcified fibrocartilage. RESULTS: A 7 ± 2.1 mm region of calcified fibrocartilage at 4 o'clock was identified from the articular face to the medial glenoid neck supporting the overlying capsulolabral footprint and was >3× thicker at the articular attachment (316 ± 153 µm) versus the glenoid neck (92 ± 66 µm). At 3 to 9 o'clock and 4 to 8 o'clock 79.2% ± 5.4% and 75.2% ± 7.8% of the glenoid osseous width was covered with articular cartilage. The labrum accounted for 13.1% ± 3.4% of the glenoid width at 4 o'clock. SEM analysis demonstrated decreased glenoid bone density at 3, 4, and 5 o'clock (P ≤ .015) and no difference (P = .448) at 9 o'clock versus central subchondral bone. CONCLUSIONS: The capsulolabral footprint contributes significantly to the glenoid face, inserts directly adjacent to the articular cartilage, and extends medially along the glenoid neck. A layer of calcified fibrocartilage lies immediately beneath the capsulolabral footprint and is 3× thicker at the articular insertion compared with the glenoid neck. Lastly, there is a bone density gradient at the anterior-inferior rim versus the central subchondral bone. CLINICAL RELEVANCE: Arthroscopic Bankart repair has been reported to have a significant failure rate in many settings. It is felt that reproducing anatomy with the repair could help improve outcomes. Based on this study's findings, an arthroscopic Bankart technique that most closely reproduces native anatomy and potentially optimizes soft-tissue healing could be performed. This includes removal of 1 to 2 mm of articular cartilage from the glenoid face with anchor placement at this location to appropriately reposition the capsulolabral complex.

Time-Dependent Changes in the Structure of Calcified Fibrocartilage in the Rat Achilles Tendon-Bone Interface With Sciatic Denervation.

The enthesis transmits a physiological load from soft to hard tissue via fibrocartilage. The histological alterations induced by this physiological loading remain unclear. This study was performed to examine the histomorphological alterations in the collagen fiber bundle alignment and depth of collagen interdigitation between the calcified fibrocartilage and the bone. We examined the Achilles enthesis of rats with sciatic denervation to explore the mechanical effects of structural changes in the enthesis. The parallelism of the collagen fiber bundles was significantly reduced 8 weeks after denervation. However, the depth of collagen interdigitation significantly increased at 2 and 4 weeks after denervation and then significantly decreased 8 weeks after denervation. In conclusion, a lack of muscle loading induced structural alterations in the distal calcified fibrocartilage. These findings suggest that while structural changes in the enthesis are necessary for the development of physiological loading, structural deformities are required in the long term. Anat Rec, 300:2166-2174, 2017. © 2017 Wiley Periodicals, Inc.

Anatomy of the capsulolabral complex and rotator interval related to glenohumeral instability.

The glenohumeral joint with instability is a common diagnosis that often requires surgery. The aim of this review was to present an overview of the anatomy of the glenohumeral joint with emphasis on instability based on the current literature and to describe the detailed anatomy and anatomical variants of the glenohumeral joint associated with anterior and posterior shoulder instability. A review was performed using PubMed/MEDLINE using key words: Search terms were "glenohumeral", "shoulder instability", "cadaver", "rotator interval", "anatomy", and "anatomical study". During the last decade, the interest in both arthroscopic repair techniques and surgical anatomy of the glenohumeral ligament (superior, middle, and inferior), labrum, and rotator interval has increased. Understanding of the rotator interval and attachment of the inferior glenohumeral ligament on the glenoid or humeral head have evolved significantly. The knowledge of the detailed anatomy and anatomical variations is essential for the surgeon in order to understand the pathology, make a correct diagnosis of instability, and select proper treatment options. Proper understanding of anatomical variants can help us avoid misdiagnosis. Level of evidence V.

Quantitative comparison of the microscopic anatomy of the human ACL femoral and tibial entheses.

The femoral enthesis of the human anterior cruciate ligament (ACL) is known to be more susceptible to injury than the tibial enthesis. To determine whether anatomic differences might help explain this difference, we quantified the microscopic appearance of both entheses in 15 unembalmed knee specimens using light microscopy, toluidine blue stain and image analysis. The amount of calcified fibrocartilage and uncalcified fibrocartilage, and the ligament entheseal attachment angle were then compared between the femoral and tibial entheses via linear mixed-effects models. The results showed marked differences in anatomy between the two entheses. The femoral enthesis exhibited a 3.9-fold more acute ligament attachment angle than the tibial enthesis (p<0.001), a 43% greater calcified fibrocartilage tissue area (p<0.001), and a 226% greater uncalcified fibrocartilage depth (p<0.001), with the latter differences being particularly pronounced in the central region. We conclude that the ACL femoral enthesis has more fibrocartilage and a more acute ligament attachment angle than the tibial enthesis, which provides insight into why it is more vulnerable to failure.

Regional fibrocartilage variations in human anterior cruciate ligament tibial insertion: a histological three-dimensional reconstruction.

PURPOSE: We studied anterior cruciate ligament (ACL) tibial insertion architecture in humans and investigated regional differences that could suggest unequal force transmission from ligament to bone. MATERIALS AND METHODS: ACL tibial insertions were processed histologically. With Photoshop software, digital images taken from the histological slides were collaged, contour lines were drawn, and different gray values were filled based on the structure. The data were exported to Amira software for three-dimensional reconstruction. RESULTS: The uncalcified fibrocartilage (UF) layer was divided into three regions: lateral, medial and posterior according to the architecture. The UF zone was significantly thicker laterally than medially or posteriorly (p < 0.05). Similarly, the calcified fibrocartilage (CF) thickness was significantly greater in the lateral part of the enthesis compared to the medial and posterior parts (p < 0.05). CONCLUSIONS: The UF quantity (more UF laterally) corresponding to the CF quantity (more CF laterally) at the ACL tibial insertion provides further evidence suggesting that the load transferred from the ACL to the tibia was greater laterally than medially and posteriorly.

The effect of light-emitting diode and laser on mandibular growth in rats.

OBJECTIVE: To evaluate the effect of a light-emitting diode (LED) and/or low-level laser (LLL) with or without the use of anterior bite jumping appliances (also known as functional appliances [FAs]) on mandibular growth in rats. MATERIALS AND METHODS: Thirty-six 8-week-old male Sprague-Dawley rats weighing 200 g were obtained from Charles River Canada (St. Constant, QC, Canada) and were divided into six groups of six animals each. Groups were as follows: group 1: LLL; group 2: LLL + FA; group 3: LED; group 4: LED + FA; group 5: FA; and group 6: control (no treatment). Mandibular growth was evaluated by histomorphometric and micro computed tomographic (microCT) analyses. RESULTS: The LED and LED + FA groups showed an increase in all condylar tissue parameters compared with other groups. CONCLUSION: The LED-treated groups showed more mandibular growth stimulation compared with the laser groups.

Normal anatomic variants of the acetabular labrum.

Within the past two decades, magnetic resonance imaging (MRI) has evolved into an integral part of noninvasive diagnostic testing for evaluation of musculoskeletal disorders. With the advancements in imaging and coil technology, assessment of small and spatially complex structures, such as the acetabular labrum, became possible. Labral tears are being diagnosed with increasing frequency with MRI. However, the medical literature reveals erratic sensitivity and specificity values of MRI, including MR arthrography, in identifying labral tears. This finding could be partly attributable to false-positive results caused by normal anatomic variants of the acetabular labrum. Additional challenges are introduced by the lack of consensus on the existence and the distributions of the normal anatomic variants of the labrum in MRI and orthopedic literature. In this article, the spectrum and incidence of these variations are discussed with emphasis on MRI features of the variant anatomy and the labral tears.

Management of labral tears of the hip in young patients.

Our understanding of labral tears in young patients has evolved significantly in recent years. Successful outcome depends on addressing all bony impingement to improve the intra-articular environment, and prevent further damage to the labrum and articular cartilage. Improved clinical outcomes are associated with labral repair; in cases of a deficient labrum, arthroscopic reconstruction techniques have been developed, with promising clinical outcomes. This article reviews the anatomy of the acetabular labrum, and discusses the pathogenesis of labral tears as well as various treatment options, including arthroscopic labral repair and reconstruction.

Normal anatomy and imaging of the hip: emphasis on impingement assessment.

A comprehensive knowledge of normal hip anatomy and imaging techniques is essential in the evaluation and assessment of the patient with hip pain. This article reviews the osseous, soft tissue, and vascular components of the hip and the normal anatomical variants encountered in routine hip imaging. Basic and advanced hip imaging is discussed with particular emphasis on radiographic and computed tomography measurements and their utility in evaluating patients with developmental hip dysplasia and femoroacetabular impingement syndrome.

The significance of calcified fibrocartilage on the cortical endplate of the translational sheep spine model.

To gain an understanding of the vertebral cortical endplate and factors that may affect the ability to achieve skeletal attachment to intervertebral implants and fusion, this study aimed to characterize the hypermineralized tissue on the cortical endplate of the vertebral body on a commonly used animal model. Skeletally mature sheep were injected with tetracycline prior to euthanasia and the C2-C3, T5-T6, and L2-L3 spinal motion segments were excised and prepared. Vertebral tissues were imaged using backscatter electron (BSE) imaging, histology, and tetracycline labeling was used to assess bone remodeling within different tissue layers. It was determined that the hypermineralized tissue layer was calcified fibrocartilage (CFC). No tetracycline labels were identified in the CFC layer, in contrast to single and double labels that were present in the underlying bone, indicating the CFC present on the cortical endplate was not being actively remodeled. The average thickness of the CFC layer was 146.3 ± 70.53 µm in the cervical region, 98.2 ± 40.29 µm in the thoracic region, and 150.89 ± 69.25 µm in the lumbar region. This difference in thickness may be attributed to the regional biomechanical properties of the spine. Results from this investigation indicate the presence of a nonremodeling tissue on the cortical endplate of the vertebral body in sheep spines, which attaches the intervertebral disc to the vertebrae. This tissue, if not removed, would likely prevent successful bony attachment to an intervertebral device in spinal fusion studies and total disc replacement surgeries.

Simple versus horizontal suture anchor repair of Bankart lesions: which better restores labral anatomy?

PURPOSE: The goal of this study was to determine which suture repair technique better restores glenoid labrum height: horizontal sutures or simple sutures. METHODS: Sixteen cadaveric glenoids, 8 per repair technique, were used to measure native labral height at the 3:00 to 6:00 positions in half-hour increments. A Bankart lesion was then created from 3:00 to 6:30. Height measurements at each time point were again taken after creation of the Bankart lesion. Repair with a 3-mm knotted suture anchor was then performed at 3:30, 4:30, and 5:30 with either a simple or horizontal suture technique, and postrepair heights were measured across all time points. RESULTS: Significant decreases in height, as compared with native height, were observed at 3:30, 4:30, and 5:30 in the simple repair group. Decreases in height of 1.4 mm (P = .044), 2.1 mm (P = .030), and 1.1 (P = .034) were observed at 3:30, 4:30, and 5:30. There was no significant decrease in height at these respective time points in the horizontal repair group. CONCLUSIONS: The in vitro horizontal mattress suture technique better restores labral height and anatomy when compared with a simple suture technique in the repair of acute Bankart lesions. CLINICAL RELEVANCE: Compared with the simple suture technique, horizontal suture repair may provide increased stability to the glenohumeral construct.

Diagnosis and management of superior labral anterior posterior tears in throwing athletes.

Injury to the superior glenoid labrum is increasingly recognized as a significant source of shoulder pain and dysfunction in the throwing athlete. Several theories have been proposed to explain the pathogenesis of superior labral anterior posterior (SLAP) tears. The clinical examination of the superior labrum-biceps tendon complex remains challenging because of a high association of other shoulder injuries in overhead athletes. Many physical examination findings have high sensitivity and low specificity. Advances in soft tissue imaging such as magnetic resonance arthrography allow for improved detection of labrum and biceps tendon lesions, although correlation with history and physical examination is critical to identify symptomatic lesions. Proper treatment of throwers with SLAP tears requires a thorough understanding of the altered biomechanics and the indications for nonoperative management and arthroscopic treatment of these lesions.

Shear mechanics of the TMJ disc: relationship to common clinical observations.

The temporomandibular joint (TMJ) is a complex hinge and gliding joint that induces significant shear loads onto the fibrocartilage TMJ disc during jaw motion. The purpose of this study was to assess regional variation in the disc's shear loading characteristics under physiologically relevant loads and to associate those mechanical findings with common clinical observations of disc fatigue and damage. Porcine TMJ discs were compressed between an axially translating bottom platen and a 2.5-cm-diameter indenter within a hydrated testing chamber. Discs were cyclically sheared at 0.5, 1, or 5 Hz to 1, 3, or 5% shear strain. Within the anterior and intermediate regions of the disc when sheared in the anteroposterior direction, both shear and compressive moduli experienced a significant decrease from instantaneous to steady state, while the posterior region's compressive modulus decreased approximately 5%, and no significant loss of shear modulus was noted. All regions retained their shear modulus within 0.5% of instantaneous values when shear was applied in the mediolateral direction. The results of the disc's regional shear mechanics suggest an observable and predictable link with the common clinical observation that the posterior region of the disc is most often the zone in which fatigue occurs, which may lead to disc damage and perforation.