Three-dimensional finite element model of elbow was established to study the effect of medial collateral ligament (MCL) in maintaining the stability of elbow joint. In the present study a three-dimensional geometric model of elbow joint was established by reverse engineering method based on the computed tomography (CT) image of healthy human elbow. In the finite element pre-processing software, the ligament and articular cartilage were constructed according to the anatomical structure, and the materials and contacts properties were given to the model. In the neutral forearm rotation position and 0° flexion angle, by comparing the simulation data of the elbow joint with the experimental data, the validity of the model is verified. The stress value and stress distribution of medial collateral ligaments were calculated at the flexion angles of elbow position in 15°, 30°, 45°, 60°, 75°, 90°, 105°, 120°, 135°, respectively. The result shows that when the elbow joint loaded at different flexion angles, the anterior bundle has the largest stress, followed by the posterior bundle, transverse bundle has the least, and the stress value of transverse bundle is trending to 0. Therefore, the anterior bundle plays leading role in maintaining the stability of the elbow, the posterior bundle plays supplementary role, and the transverse bundle does little. Furthermore, the present study will provide theoretical basis for clinical recognizing and therapy of elbow instability caused by medial collateral ligament injury.
Biomechanical Phenomena ; Cadaver ; Collateral Ligaments ; physiology ; Elbow Joint ; physiology ; Finite Element Analysis ; Humans ; Range of Motion, Articular ; Tomography, X-Ray Computed

BACKGROUND: Tendon and ligament injuries accounted for 30% of all musculoskeletal consultations with 4 million new incidences worldwide each year and thus imposed a significant burden to the society and the economy. Damaged tendon and ligament can severely affect the normal body movement and might lead to many complications if not treated promptly and adequately. Current conventional treatment through surgical repair and tissue graft are ineffective with a high rate of recurrence.METHODS: In this review, we first discussed the anatomy, physiology and pathophysiology of tendon and ligament injuries and its current treatment. Secondly, we explored the current role of tendon and ligament tissue engineering, describing its recent advances. After that, we also described stem cell and cell secreted product approaches in tendon and ligament injuries. Lastly, we examined the role of the bioreactor and mechanical loading in in vitro maturation of engineered tendon and ligament.RESULTS: Tissue engineering offers various alternative ways of treatment from biological tissue constructs to stem cell therapy and cell secreted products. Bioreactor with mechanical stimulation is instrumental in preparing mature engineered tendon and ligament substitutes in vitro.CONCLUSIONS: Tissue engineering showed great promise in replacing the damaged tendon and ligament. However, more study is needed to develop ideal engineered tendon and ligament.
Bioreactors ; Exosomes ; In Vitro Techniques ; Incidence ; Ligaments ; Physiology ; Recurrence ; Referral and Consultation ; Stem Cells ; Tendons ; Tissue Engineering ; Transplants

OBJECTIVETo study the biomechanical change of the craniovertebral junction in conditions of atlas assimilation.

METHODSMimics software was used to process CT data of the craniovertebral junction in a health adult to obtain the three-dimensional reconstruction and the cloudy points of C1, C2 and part of the occipital bone. Then the cloudy points were imported into the Abaqus 6. 8 software to establish the occipito-atlantoaxial finite element model in normal structure. According to the established model in normal structure, the model in conditions of atlas assimilation was set by changing the model parameters. Both models of normal structure and atlas assimilation were loaded with 1. 5 N . m static moment to simulate four motions of flexion, extension, lateral bending and axial rotation respectively. The movement characteristics,joint stress force and ligament deformation was analyzed.

RESULTSUnder 1. 5 N . m moment, in model of atlas assimilation the C1-C2 range of movement decreased from 13. 55° to 11.88° in flexion,increased from 13. 22° to 15. 24° in extension and from 4. 05° to 4. 23° in lateral bending and remained unchanged in axial rotation when compared with the normal model. In flexion movement, the contact force of the atlanto-dental joint increased from 1. 59 MPa to 3. 28 MPa and the deflection of apical ligament, tectorial membrane and alar ligament increased 129. 1%, 157. 6% and 75. 1% respectively when compared with the normal model.

CONCLUSIONSThe normal C1-C2 motion mode is destructed in conditions of atlas assimilation, leading to the changes of the range of movement,joint stress force and the ligament deformation at C1 C2 junction. The atlantoaxial instability will likely occur in flexion motion.

Atlanto-Axial Joint ; physiology ; Biomechanical Phenomena ; Cervical Atlas ; physiology ; Cervical Vertebrae ; Finite Element Analysis ; Humans ; Imaging, Three-Dimensional ; Joint Instability ; Ligaments, Articular ; Occipital Bone ; Range of Motion, Articular ; Rotation

BACKGROUNDAlthough various systemic and local factors such as abnormal carbohydrate or calcium metabolism, aging, and hormonal disturbances have been suggested as causes of ossification of the posterior longitudinal ligament (OPLL), the etiology of OPLL is not fully understood. The purpose of this study was to investigate whether bone morphogenetic protein (BMP)-2 is a candidate gene to modify the susceptibility of OPLL and the mechanism of signal transduction in ossification.

METHODSA total of 420 OPLL patients and 506 age- and sex-matched controls were studied. The complete coding sequence of the human BMP-2 gene was analyzed using polymerase chain reaction (PCR) and direct sequencing. All single nucleotide polymorphisms (SNPs) were detected and genotyped. BMP-2 expression vectors containing positive polymorphisms were constructed and transfected into the C3H10T1/2 cells. The expression of BMP-2 and the Smad signal pathway in positive cell clones were detected by Western blotting. The alkaline phosphatase (ALP) activity was determined using quantitative detection kits.

RESULTSThe frequencies for the 109T > G and 570A > T polymorphisms were different between the case and control groups. The "TG" genotype in 109T > G polymorphism is associated with the occurrence of OPLL, the frequency of the "G" allele is significantly higher in patients with OPLL than in control subjects (P < 0.001). The "AT" genotype in 570A > T polymorphism is associated with the occurrence of OPLL, the frequency of the "T" allele is significantly higher in patients with OPLL than in control subjects (P = 0.005). Western blotting analysis revealed that the expression of P-Smad1/5/8 protein transfected by wild-type or mutant expression vectors were significantly higher than control groups (P < 0.05), but there was no statistical difference in each experimental group (P > 0.05). The expression of Smad4 protein transfected by wild-type or mutant expression vectors was significantly higher than control groups (P < 0.05). The expression of Smad4 protein transfected by pcDNA3.1-BMP2 (109G) and pcDNA3.1-BMP2 (109G, 570T) was significantly higher than the other experimental groups (P < 0.05). The increase in ALP activity has been detected in pcDNA3.1-BMP2 (109G) and pcDNA3.1-BMP2 (109G, 570T) transfected cells up to 4 weeks after stable transfection. Activity of ALP was (30.56 ± 0.46) nmol×min(-1)×mg(-1) protein and (29.62 ± 0.68) nmol×min(-1)×mg(-1) protein, respectively. This was statistically different compared with the other experimental groups (P < 0.05).

CONCLUSIONSBMP-2 is the predisposing gene of OPLL. The "TG" genotype in the 109T > G and the "AT" genotype in the 570A > T polymorphisms are associated with the occurrence of OPLL. The 109T > G polymorphism in exon-2 of the BMP-2 gene is positively associated with the level of Smad4 protein expression and the activity of ALP. The Smad mediated signaling pathway plays an important role during the pathological process of OPLL induced by SNPs of BMP-2 gene.

Adult ; Aged ; Bone Morphogenetic Protein 2 ; genetics ; Cells, Cultured ; Female ; Humans ; In Situ Hybridization ; Longitudinal Ligaments ; metabolism ; Male ; Middle Aged ; Polymorphism, Single Nucleotide ; genetics ; Signal Transduction ; genetics ; physiology ; Smad Proteins ; metabolism ; Spine ; metabolism

OBJECTIVETo discuss the midface aging mechanism through anatomic study of malar fat pad.

METHODS10 fresh adult cadaveric heads (20 sides) fixed by vascular perfusion of formalin were used for anatomic study with microsurgery technique under microscope. The midfacial ligament and connective tissue between skin and subcutaneous fat were observed carefully in different parts of midface. The location, shape and extent of malar fat pad was also recorded and photographed.

RESULTSThe malar fat pad has a triangle shape. The bottom is a curve along the orbicularis retaining ligament at the lower eyelid. The fat pad is extended internally to the nasolabial fold and labiomandibular fold, externally from the major zygomatic muscle end point at the malar surface to the angulus oris and submandibular edge. (2) The malar fat pad is composed of meshed fibrous tissue, with big fat particles in it. It becomes tight when being stretched in horizontal direction along nasolabial fold and loosen when being stretched in vertical direction. (3) There is tight connection between skin and fat pad, which is divided into four areas as I, II, III, IV. The areas I, II, III are strip-shaped parelled to the nasolabial fold. The area IV is a irregular quadrilateral. (4) There are six fixation ligaments between malar fat pad and deep tissue: orbicularis retaining ligament upper layer of lower eyelid, orbicularis retaining ligament substratum of lower eyelid, zygomaticus ligament, zygomatic cutaneous ligament, zygomatic cutaneous ligament substratum, platysma There are four closely connected areas cutaneous forward ligament, cheek maxilla ligament.

CONCLUSIONSbetween the facial skin and malar fat pad which makes malar fat pad and skin keep relatively consistent. The malar fat pad moving down mainly resulted from slack of ligaments support which is one of the reasons for aging face.

Adipose Tissue ; anatomy & histology ; physiology ; Cadaver ; Cheek ; Eyelids ; anatomy & histology ; physiology ; Face ; anatomy & histology ; physiology ; Facial Muscles ; anatomy & histology ; physiology ; Head ; Humans ; Ligaments ; anatomy & histology ; physiology ; Lip ; anatomy & histology ; physiology ; Skin ; anatomy & histology ; Skin Aging ; pathology ; physiology

OBJECTIVETo create a 3-dimensional finite element model of knee ligaments and to analyse the stress changes of lateral collateral ligament (LCL) with or without displaced movements at different knee flexion conditions.

METHODSA four-major-ligament contained knee specimen from an adult died of skull injury was prepared for CT scanning with the detectable ligament insertion footprints, locations and orientations precisely marked in advance. The CT scanning images were converted to a 3-dimensional model of the knee with the 3-dimensional reconstruction technique and transformed into finite element model by the software of ANSYS. The model was validated using experimental and numerical results obtained by other scientists. The natural stress changes of LCL at five different knee flexion angles (0 degree, 30 degree, 60 degree, 90 degree, 120 degree) and under various motions of anterior-posterior tibial translation, tibial varus rotation and internal-external tibial rotation were measured.

RESULTSThe maximum stress reached to 87%-113% versus natural stress in varus motion at early 30 degree of knee flexions. The stress values were smaller than the peak value of natural stress at 0 degree (knee full extension) when knee bending was over 60 degree of flexion in anterior-posterior tibial translation and internal-external rotation.

CONCLUSIONLCL is vulnerable to varus motion in almost all knee bending positions and susceptible to anterior-posterior tibial translation or internal-external rotation at early 30 degree of knee flexions.

Anterior Cruciate Ligament ; physiology ; Collateral Ligaments ; physiology ; Finite Element Analysis ; Humans ; Knee Joint ; physiology ; Stress, Mechanical

BACKGROUNDWe investigated the impact of eliminating the impingement between extensor mechanism and tibial insert on patellar tracking and patellar ligament tension in high knee flexion.

METHODSSix cadaveric specimens were tested on an Oxford-type testing rig. The Genesis II knee system was implanted into each specimen knee with the traditional tibial insert and high-flex insert successively. Compared to traditional insert, the high-flex insert was characterized with a chambered anterior post and a chambered anterior lip which eliminates patella-post and patellar ligament-anterior lip impingements. The patella was tracked with an NDI Optotrak Certus system. The patellar ligament tension was measured using a NKB S-type tension transducer.

RESULTSThere was a decrease of resultant patellar translation relative to the femur with statistically significant (P<0.05) at 90 degrees to 150 degrees of knee flexion and a decrease of patellar ligament tension with statistical significance (P<0.05) at 100 degrees, 120 degrees, 130 degrees, and 140 degrees of flexion using high-flex insert compared to traditional insert.

CONCLUSIONSEliminating the impingement between extensor mechanism and implant in high knee flexion altered patellar tracking and reduced patellar ligament tension, which would facilitate high knee flexion.

Biomechanical Phenomena ; Humans ; In Vitro Techniques ; Knee Joint ; physiology ; Ligaments, Articular ; physiology ; Patellar Ligament ; physiology ; Range of Motion, Articular ; physiology

OBJECTIVE: To develop a novel three dimensional finite element(FE) model of the human pelvis and investigate the biomechanics of the pelvic injury and explore the applications of FE approach in forensic medicine. METHODS: The FE model of pelvis including bilateral iliac bones, sacrum, bilateral femurs, joint cartilages and ligaments was developed with Mimics 13.1 based on the CT images. The CT value of material properties were assigned. A static pressure of 600 N was applied at the upper surface of the sacrum endplate downwards along the vertical axis of sacral bone to validate the model. To simulate the side impacts, the lateral forces of 1, 2, 3, 4 and 5 kN were applied to the trochanter surface of right femur, respectively. The von Mises stress contours, displacement contours and stress distribution curves were subsequently calculated. RESULTS: An integrated FE model of pelvis including the joint cartilages and ligaments was successfully established. The model geometry coincided well with the CT images. The stress distributions of pelvis in erect position mainly located near the sacroiliac joints and the greater sciatic notches. Stress concentration was found on the superior and inferior pubis ramus, hip and sacroiliac joints on both sides under side impacts. CONCLUSION The established FE model has accurate and reliable biomechanical features. The FE model can be used to simulate injury and provide intuitive and accurate evidence for medicolegal expertise.
Biomechanical Phenomena ; Cadaver ; Computer Simulation ; Finite Element Analysis ; Hip Joint/physiology* ; Humans ; Image Processing, Computer-Assisted ; Imaging, Three-Dimensional/methods* ; Ligaments/physiology* ; Male ; Models, Anatomic ; Models, Biological ; Pelvis/physiology* ; Pressure ; Software ; Stress, Mechanical ; Tomography, Spiral Computed/methods* ; Weight-Bearing/physiology*

The motions of humeral external rotation with and without the anterior band of inferior glenohumeral ligament complex (AB-IGHL) were simulated. As a result of comparison, the contact pressure and contact force are all higher when the AB-IGHL was included in the model. Therefore, it is theoretically proved that the AB-IGHL constrains the motion of humerus during humeral external rotation. The predicted values for von Mises and the maximum tense force in the AB-IGHL were 4.433 MPa and 37.32 N respectively, occurring on the humeral side of the ligament. This approach to evaluating the function of AB-IGHL would provide greater insight into the mechanical contribution of AB-IGHL to joint function, identify the mechanism of a hurt to AB-IGHL, and provide a quantitative means for developing low-risk rehabilitation protocols.
Finite Element Analysis ; Humans ; Ligaments, Articular ; physiology ; Range of Motion, Articular ; Rotation ; Shoulder Joint ; anatomy & histology ; physiology ; Tensile Strength

Some 3D finite element systemic models are currently established and used to simulate the foot biomechanical state. However, during most of these 3D foot finite element static analyses, ligaments and plantar fascia are generally defined by connecting the corresponding attachment points on the bones, and the spaces between the bones are fused together by solid elements with given cartilage stiffness to simulate the connection of bones. This "connection of bones" takes the place of the real interactions between neighbored bones and enhances the structure of foot, which possibly leads to the result that the effects of ligaments and other soft tissues are completely replaced by the effect of articular cartilages. Thereby, ligaments and other soft tissues maybe not play an inherent role in the finite element analysis. The objective of this study was to estimate whether there exists the effect of ligaments and plantar fascia on the biomechanical behaviors of the foot tissue stress distribution and foot structure deformation during the balanced standing stance and static finite element analysis.
Adult ; Biomechanical Phenomena ; Computer Simulation ; Fascia ; physiology ; Foot ; diagnostic imaging ; physiology ; Humans ; Ligaments ; physiology ; Male ; Models, Biological ; Radiography ; Stress, Mechanical