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PubMedDate not supplied

Endoscopically assisted annular ligament release in horses.

An endoscopically assisted technique for internally dividing the palmar or plantar annular ligament was developed in six cadaver limb specimens and two anesthetized horses. Under arthroscopic view, a slotted cannula was inserted into the digital sheath through a stab wound proximal to the annular ligament and advanced through the fetlock canal superficial to the flexor tendons with the slot oriented toward the fibers of the annular ligament. Division of the annular ligament by 90-degree tipped open and guarded blades was observed and verified by direct arthroscopic view. At necropsy, complete division of the annular ligament without iatrogenic damage to the neurovascular structures was confirmed by dissection. Annular ligament division was performed in seven horses with complex tenosynovitis conditions. Tenoscopic examination and removal of tendon and digital sheath adhesions, masses, and bands was followed by endoscopically assisted annular ligament transection. At follow-up, five horses were sound athletes without recurrent digital sheath problems, one horse had residual lameness, and one horse was still convalescing.

Animals↗
PubMed2004

The involvement of platelet-derived growth factor receptors and insulin-like growth factor-I receptors signaling during mineralized nodule formation by human periodontal ligament cells.

BACKGROUND AND OBJECTIVE: Periodontal ligament cells are regarded to have the capacity to differentiate into cementoblasts or osteoblasts, and are capable of forming a mineralized nodule in vitro. However, the precise mechanisms are unclear. Here we evaluated the possible involvement of growth factor receptors, such as the platelet-derived growth factor receptor (PDGFR), insulin-like growth factor-I receptor (IGF-IR), and epidermal growth factor receptor (EGFR) on periodontal ligament cells and their ligands during periodontal ligament cells differentiation in vitro. METHODS: Human periodontal ligament cells were differentiated via culturing in the presence of dexamethasone, ascorbic acid, and beta-glycerophosphate for mineralized nodule formation, characterized by von Kossa staining. Expressions of receptors and their ligands were analyzed by flow cytometry/reverse transcription-polymerase chain reaction. RESULTS: During the differentiation, PDGFR-alpha was held at a lower level compared with the control. PDGFR-beta, however, was maintained at a slightly higher level that was reversed to the control level when mineralized nodules formed. In contrast, IGF-IR and EGFR were not substantially different from the control. The mineralized nodule formation was strongly inhibited by a PDGFR kinase blocker (AG1295 and AG1296), partially inhibited by an IGF-IR kinase blocker (I-Ome-AG538 and AG1024), and not inhibited by an EGFR kinase blocker (AG99). PDGF-A, PDGF-C, PDGF-D, IGF-I, and IGF-II, but not PDGF-B, were expressed on the control as well as dexamethasone/ascorbic acid-treated periodontal ligament cells during mineralized nodule formation; however, the pattern of their expressions was quite different. CONCLUSION: These findings suggest that a pathway of PDGFs/PDGFR and IGFs/IGF-IR on periodontal ligament cells are involved during mineralized nodule formation, and that PDGFs and IGFs expressed by periodontal ligament cells may contribute to the formation.

Adolescent↗
PubMed1999

Re-innervation in the canine periodontal ligament of replanted teeth using an antibody to protein gene product 9.5: an immunohistochemical study.

The re-innervation process in the periodontal ligament of replanted canine teeth was examined by immunohistochemistry for protein gene product 9.5 (PGP 9.5), a general marker for neurons, and by electron microscopy. Within 1 week of replantation, the periodontal fibers had regenerated, filling the narrow spaces between the alveolar bone and the root surface around the cervical and apical regions. Near the root apex, however, no PGP 9.5-immunopositive nerve fibers were found in the regenerated periodontal ligament except for those in the alveolar half of the ligament. At 2 weeks after replantation, many nerve fibers positive for PGP 9.5 had ascended the periodontal ligament from the thick nerve bundles located near the root apex. Fine nerve endings showing complicated ramification were also present in the apical region. By 3 or 4 weeks after replantation, the vascular network was regenerated and principal periodontal fibers were re-established throughout the entire length of the periodontal ligament. The extensively ramified PGP 9.5-immunopositive structures had increased in thickness and density and showed characteristic tree-like profiles by 3 weeks. Electron microscopy confirmed that most of these structures were Ruffini-like endings, and demonstrated that such nerve terminals were almost regenerated by 4 weeks post-replantation. These results indicated that, in the periodontal ligament of replanted canine teeth, the regeneration of the nerve fibers including mechanosensory receptors first showed signs of regeneration by 2 weeks following tooth replantation and proceeded rapidly thereafter. Regeneration of the periodontal ligament including fiber architecture as well as vascular and neural elements was almost complete by 4 weeks after replantation.

Animals↗
PubMed2001

Anatomical variation of the sphenomandibular ligament.

The sphenomandibular ligament, which is derived from the sheath of Meckel's cartilage, is a fibrous structure that passes between the spine of the sphenoid bone and the lingula of the mandible. Although anatomical texts provide basic descriptions of this structure, there are few published reports of the extent of its variability or its possible clinical implications. The aim of this study was to provide a detailed description of the nature and extent of anatomical variability in the sphenomandibular ligament of seven human cadavers. Dissections of sagittally sectioned heads were performed using a medial approach that involved displacement of the tongue and mucosal tissues in the oral cavity and oropharynx, then reflection of the medial pterygoid muscle. The ligaments ranged in shape from thin bands that descended for a short distance from the spine of the sphenoid to broad bi-concave ligaments with prominent insertions. The mylohyoid nerve was seen to pass behind the ligament in all specimens, emerging from the postero-inferior border of the mandibular attachment before running into the mylohyoid groove on the medial surface of the ramus. Lying in the pterygomandibular space, the ligament was surrounded by fascia, both structures presenting potential barriers to the diffusion of local anaesthetic solution if injected medially. The appearance of the lingula also varied, and did not seem to reflect the size of attachment of the ligament, suggesting an alternative explanation of lingula morphology, perhaps related to a continuation of the mylohyoid ridge and anterior border of the mylohyoid groove.

Humans↗
PubMed1996

Functional development of the sheep diaphragmatic ligament.

1. The diaphragmatic ligament, which lines the thoracic surface of the diaphragm, plays a major role in setting the passive compliance of the diaphragm in the adult. Since many elastic tissues are more compliant at younger ages, our aim was to determine whether this diaphragmatic ligament plays an important role during development of the diaphragm. 2. We examined the passive biaxial length-tension properties of the isolated mid-costal diaphragm from fetal, newborn and adult sheep; initially with the diaphragm intact and then with the diaphragmatic ligament removed to reveal its functional significance. 3. We found that unlike other elastic tissues the diaphragmatic ligament is stiffer in early development than in the adult. The diaphragmatic ligament supports about 75% of the passive tension in the diaphragm in the 121 day fetus (term at 147 days) declining to about 50% from 3 weeks of age. The fetal diaphragm muscle fibres are exposed to 1-7 kPa of stress over the last 26 days of gestation. 4. We suggest that the diaphragmatic ligament provides a structural framework on which the muscle fibres of the diaphragm grow in fetal life, and that the ligament's elasticity is regulated to maintain a low and constant stress on the diaphragm muscle fibres during development.

Age Factors↗
PubMed2000

Ligament mechanics during three degree-of-freedom motion at the acromioclavicular joint.

The development of effective treatment and reconstruction procedures for injuries to the soft tissues around the acromioclavicular (AC) joint relies on a comprehensive understanding of overall joint function. The objective of this study was to determine the magnitude and direction of the in situ forces in the AC capsular and coracoclavicular ligaments as well as the resulting joint kinematics during application of three external loading conditions while allowing three degree-of-freedom joint motion. A robotic/universal force-moment sensor testing system was utilized to determine the in situ forces in the soft tissue structures and the resulting joint kinematics. The clavicle translated 5.1+/-2.0, 5.6+/-2.2, and 4.2+/-1.9 mm during application of a 70 N load in the anterior, posterior, and superior directions, respectively, representing almost a 50% increase over previous studies using similar load magnitudes. In response to an anterior load, the magnitude of in situ force in the superior AC ligament (35+/-18 N) was found to be greater (p<0.05) than the force in the trapezoid and conoid ligaments. In contrast, the magnitude of in situ force in the conoid (49+/-22 N) was significantly greater (p<0.05) than all other ligaments in response to a superior load. Additionally, the directions of the force vector representing the conoid and trapezoid were different, being located in opposing quadrants of the posterior axis of the scapula with this loading condition. Our data suggest that the kinematic constraints placed on the AC joint during loading affect the resulting joint motion and that the magnitude and direction of force in each ligament are affected by the coupled motions that occur. Based on the differences in magnitude and direction of the in situ force in the coracoclavicular ligaments with each loading condition, surgical procedures should reconstruct these ligaments in a more anatomical manner or treat them separately to prevent joint degeneration.

Acromioclavicular Joint↗
PubMed1995

The use of a universal force-moment sensor to determine in-situ forces in ligaments: a new methodology.

Determination of ligament forces is an integral part of understanding their contribution during motion and external loading of an intact joint. While almost all previous investigations have reported only the magnitude of tension, this alone cannot adequately describe the function of a particular ligament. An alternative approach to determine the in-situ forces in ligaments has been developed which utilizes a universal force-moment sensor in conjunction with a force transformation scheme. In addition to providing the magnitude of ligament force, the direction and point of application of this in-situ force can also be determined. Further, the approach does not require mechanical contact with the ligament. Application of this new methodology is demonstrated for the human anterior cruciate ligament in the present study (n = 7) although it may be similarly applied to other ligaments at the knee or in other synovial joints of the human body.

Aged↗
PubMed1995

A new device and method for controlling the load in rabbit medial collateral ligament reconstructions.

In order to study the effect of intra-operative tensioning on the laxity and strength of healing ligament grafts in an animal model, a method of quantifying graft tension was needed. In this study a sensitive ligament tensioning device was developed to measure accurately the prefixation loads in the rabbit medial collateral ligament (MCL) graft. To verify that reproducible changes in ligament tension could be created with the tensioning device, a group of animals had their MCL grafts replaced at one of three different graft loads (tight, anatomic, or loose). The tensioning device consists of two posts which move relative to one another by means of an axial screw. The movable post, which is inserted into the tibial bone island of the MCL graft has a series of strain gauges which can measure the tension applied to the graft. The stationary post attaches to the tibial shaft, permitting the ligament graft to be tensioned relative to this fixed point. After graft tensioning and fixation, the animals were euthanized immediately postoperatively and their ligament load-deformation behavior was measured using an Instron materials testing machine. Specific measures of low load behavior was taken to quantify ligament laxity. Our results demonstrate that the tensioning device was capable of reproducibly altering prefixation graft load intra-operatively as well as MCL laxity immediately postoperatively. A baseline of laxity values was thus developed to follow changes in this laxity measure for future studies of MCL graft healing in this model.

Animals↗
PubMed1998

Increasing quadriceps loads affect the lengths of the ligaments and the kinematics of the knee.

The relationships between the lengths of the ligaments and kinematics of the knee and quadriceps load, for low to physiologic levels of quadriceps loads, have not previously been studied. We investigated the effects of increasing levels of quadriceps force, necessary to balance increasing levels of externally applied flexion moments, on the kinematics of the tibiofemoral joint and on the separation distances between insertions of selected fibers of the major ligaments of the knee in twelve cadavera. Static measurements were made using a six-degree-of-freedom digitizer for flexion angles ranging from 0 to 120 deg in 15 deg increments. Quadriceps generated extension of the knee was performed by applying loads to the quadriceps tendon to equilibrate each of four magnitudes of external flexion moments equivalent to 8.33, 16.67, 25.00, and 33.33 percent of values previously reported for maximum isometric extension moments. The magnitude of quadriceps force increased linearly (p < 0.0001) as external flexion moment increased throughout the entire range of flexion. Anterior translation, internal rotation, and abduction of the tibia increased linearly (p < 0.0001, p < 0.001, p < 0.001) as external flexion moment and, hence, quadriceps load increased. For the fibers studied, the anterior cruciate ligament (p < 0.0076), posterior cruciate ligament (p < 0.0001), and medial collateral ligament (p < 0.0383) lengthened linearly while the lateral collateral ligament (p < 0.0124) shortened linearly as quadriceps load increased. Based on these results for low to physiologic levels of quadriceps loads, it is reasonable to assume that the ligament lengths or knee kinematics expected with higher quadriceps loads can be extrapolated.

Adult↗
PubMed1991

Distinguishing biomechanical properties of intrinsic and extrinsic human wrist ligaments.

Two intrinsic (scapholunate and lunotriquetral) and two extrinsic (radiolunate and radiocapitate) wrist ligaments were studied at high and low elongation rates (1 and 100 mm/min). Statistically significant differences among all four ligaments were noted for the viscoelastic and elastic components of stress versus strain for the fully recoverable strain and early permanent deformation stress for all ligaments. Intrinsic ligaments became permanently deformed at statistically significantly higher strain levels than the extrinsic ligaments and accept larger permanent deformation at strain levels below evident fiber failure. Ultimate strength data demonstrated significant rate dependency for stress and strain for all ligaments. Intrinsic ligaments failed statistically greater stress and strain levels than the extrinsic group. Some clinical implications of these findings are discussed.

Adult↗
PubMed1995

Histological changes associated with an artificial anterior cruciate ligament.

AIMS: To investigate the histopathological features of the synovial lining of the knee following implantation of an artificial cruciate ligament. METHODS: Eighty two patients underwent anterior cruciate ligament reconstruction for chronic, symptomatic instability of the knee. The cruciate ligament was reconstructed with a scaffold type prosthetic ligament. All patients underwent arthroscopy at the time of cruciate reconstruction and also as a "second look" procedure at a mean 26.5 months later, at which time synovial biopsy specimens were obtained in all cases. RESULTS: The most frequent histological finding was granulomatous synovitis in 48% (39/82) of patients. Particulate polyester debris produced a greater response than carbon fibres. In 24% (20/82), nonspecific inflammation was present and in 28% (23/82) the synovium was considered normal. When the prosthetic ligament was fully covered by soft tissue in-growth, a granulomatous reaction was present in 42% (24/57), irrespective of whether the ligament was partially or totally uncovered. Stabilisation of the joint did not prevent subsequent deterioration in the articular cartilage; other factors such as increasing patient age, interval between injury and reconstruction and altered knee kinematics after reconstruction are probably important. Granulomatous synovitis was not associated with progressive chondral changes. CONCLUSIONS: Although present in 48% of cases, granulomatous synovitis was not shown to have adverse effects on either chondral surface or the prosthetic material of the ligament. Rupture of the implant is caused by mechanical factors and granulomatous synovitis is not responsible for implant failure.

Adolescent↗
PubMed1995

MR imaging of the major carpal stabilizing ligaments: normal anatomy and clinical examples.

The integrity of the ligamentous network of the wrist is critical, as disruption of this network may result in carpal instability and pain. The extrinsic (radiocarpal) and intrinsic (intercarpal) ligaments that maintain carpal stability can be evaluated with magnetic resonance (MR) imaging. The major extrinsic ligaments are the radioscaphocapitate, radiolunotriquetral, short radiolunate, and dorsal radiocarpal ligaments. The scapholunate and lunotriquetral ligaments are the most important intrinsic ligaments and the primary wrist stabilizers. The most common causes of carpal instability are unstable fracture of the scaphoid, scapholunate dissociation, and lunotriquetral dissociation. Carpal instability can be diagnosed from the sagittal MR image that includes the capitate, lunate, and radius and from the sagittal MR image that includes the scaphoid and radius. Knowledge of the MR imaging appearances of the major carpal stabilizing ligaments and common patterns of carpal instability allows more precise diagnosis in cases of wrist pain.

Carpal Bones↗
PubMedDate not supplied

Extrinsic and intrinsic ligaments of the wrist: normal and pathologic anatomy at MR arthrography with three-compartment enhancement.

The ligaments of the wrist have been demonstrated with magnetic resonance (MR) imaging by many authors. Distinction has been made between the extrinsic, or radiocarpal and ulnocarpal, ligaments and the intrinsic, or intercarpal, ligaments. The stability of the wrist depends on numerous ligaments: The volar ligaments are important stabilizers of the wrist, whereas the dorsal ligaments are less crucial for wrist stability. An MR imaging protocol that demonstrates these structures with high resolution has been developed. Cadaveric wrists are imaged with a spoiled gradient-recalled-echo volume-acquisition technique with fat suppression after three-compartment enhancement with a contrast agent containing gadolinium. The specimens are then sectioned, and the anatomic and pathologic findings are correlated with the findings on the MR images. The extrinsic and intrinsic ligaments of the wrist are clearly demonstrated with this technique. This protocol was designed for anatomic study and promotes understanding of the anatomy and biomechanics of the wrist; it is not intended for clinical use.

Angiography↗
PubMed2007

Medial collateral ligament complex of the ankle: MR appearance in asymptomatic subjects.

PURPOSE: To prospectively characterize the spin-echo magnetic resonance (MR) imaging appearance of the medial collateral ligament (MCL) complex of the ankle in asymptomatic volunteers. MATERIALS AND METHODS: The study was approved by institutional review board. Informed consent was obtained. MR images in 56 asymptomatic subjects (29 women, 27 men; mean age, 40.7 years; range, 23-60 years) were analyzed by two musculoskeletal radiologists. Visibility and signal intensity characteristics were analyzed for deep (anterior and posterior tibiotalar ligaments [TTLs]) and superficial (tibionavicular ligament [TNL], tibiospring ligament [TSL], and tibiocalcaneal ligament [TCL]) components of the MCL complex. Thickness of ligaments was compared between sexes (Mann-Whitney U test). Associations between age and variables of signal intensity characteristics and morphology were evaluated with Kruskal-Wallis test. RESULTS: Anterior and posterior TTLs, TNL, TSL, and TCL were visible in 31 (55%), 56 (100%), 31 (55%), 56 (100%), and 49 (88%) subjects, respectively. On T1-weighted images, anterior and posterior TTLs, TNL, TSL, and TCL were more commonly of intermediate signal intensity than hypointense (77%, 100%, 93%, 50%, and 73% of subjects, respectively); on T2-weighted images, they were commonly hypointense (55%, 52%, 42%, 75%, and 78% of subjects, respectively). On T2-weighted images, posterior TTL had a striated appearance that was significantly associated with age (P = .004) in 89% of subjects: In subjects younger than 45 years, this striated appearance was present. On T1-weighted images, striation was present in 48% of subjects. Striation was uncommon in remaining ligaments. Mean thickness and range were 1.5 mm and 1-4 mm (anterior TTL), 8.2 mm and 6-11 mm (posterior TTL), 1.6 mm and 1-2 mm (TNL), 2.0 mm and 1-4 mm (TSL), and 1.2 mm and 1-3 mm (TCL). TNL (P = .001) and TSL (P = .003) were significantly thicker in men than in women. CONCLUSION: In asymptomatic volunteers, posterior TTL and TSL were always visible, but anterior TTL and TNL are only seen in approximately half of subjects. Posterior TTL has a typically striated appearance.

Adult↗
PubMedDate not supplied

Median arcuate ligament syndrome: evaluation with CT angiography.

The median arcuate ligament is a fibrous arch that unites the diaphragmatic crura on either side of the aortic hiatus. The ligament usually passes superior to the origin of the celiac axis. However, in some people, the ligament inserts low and thus crosses the proximal portion of the celiac axis, causing compression and sometimes resulting in abdominal pain. The diagnosis of clinically significant celiac axis compression, referred to as median arcuate ligament syndrome, is traditionally made with conventional angiography; however, the condition can now be diagnosed with three-dimensional computed tomographic (CT) angiography. In patients with median arcuate ligament syndrome, CT angiograms demonstrate a characteristic focal narrowing in the proximal celiac axis. The focal narrowing has a characteristic hooked appearance, which can help distinguish this condition from other causes of celiac artery narrowing, such as atherosclerotic disease. Once the disorder has been diagnosed, surgery can be performed to relieve the compression. In some patients, the ligamentous constriction of the celiac axis causes vascular damage, which may require vascular reconstruction. CT angiography can play a role in the diagnosis of median arcuate ligament syndrome by demonstrating the characteristic focal narrowing of the celiac artery in patients presenting with the appropriate clinical symptoms.

Angiography↗
PubMed1985

Comparative development of thoracic intervertebral discs and intra-articular ligaments in the human, monkey, mouse, and cat.

Developmental features of thoracic intervertrebral discs and their association in the adult with other vertebral structures were investigated in four species. The human anulus fibrosus, nucleus pulposus, and intra-articular ligaments were compared to those of the fetal rhesus monkey, mouse, and kitten. Photomicrographs of transverse sections of intervertebral discs document the presence of intra-articular ligaments in fetuses of these four species. Both transverse and sagittal sections of kittens were used to identify the intercapital ligament as it differentiated from the dorsal part of the intra-articular ligament. Relatively frequent dorsal herniation of the thoracic nucleus pulposus in humans may be due to the vestigial nature of the human intra-articular ligament. Quadrupeds have well-developed intra-articular ligaments, which explains anatomically the paucity of dorsal protrusions of the nucleus pulposus into the vertebral canal in the thoracic region of the cat and mouse when compared to the human. The intra-articular ligament was closely associated with the developing prenatal mammalian intervertebral disc in the four species studied, and this relationship and its surgical importance are described.

Anatomy, Comparative↗
PubMed1992

Functional construction of the sacroiliac ligamentous apparatus.

The sacroiliac ligamentous apparatus was examined as a part of a biomechanical pelvis-lower extremities system. The ligamentous apparatus of two pelves was freed, and the findings concerning the ligaments and their direction were drawn by a modular constructed, three-dimensional calculator model of the pelvic region. The ligamentous apparatus of the sacroiliac joint belongs to a functional system. Its task is to minimize every movement in this amphiarthrosis. The ligamentous apparatus shows an adaptation to strong or long-time-acting stresses. The junction between the os sacrum, pelvis and the ligamentous apparatus of the sacroiliac joint can be described as self-tightening. Local stresses are also reduced by the ligaments. A loosening in this system, which has to fix the os sacrum to the pelvic girdle, leads to a static insufficiency. The consequence is pain due to an irritation of the lumbosacral trunk. The exact description of the structure allows a representation according to the laws of similarity mechanics. With such a representation one can build up a computer-aided biomechanical model of the pelvis-lower extremities region. Examples for such a model are biomechanical finite-element models. By observing the laws of similarity mechanics (an exact description of geometric, physical and functional conditions) an efficient biomechanical model can be constructed that also takes into consideration the complex functional circumstances, in contrast to previous models. In order to construct such a model, one has to feed the findings of the examination into a data bank, which has to be demanded.

Biomechanical Phenomena↗
PubMedDate not supplied

The biomechanical interdependence between the anterior cruciate ligament replacement graft and the medial meniscus.

To establish a quantitative biomechanical relationship between the anterior cruciate ligament graft and the medial meniscus, 10 human cadaveric knees were examined using the robotic/universal force-moment sensor testing system. In response to a combined 134-N anterior and 200-N axial compressive tibial load, the resulting kinematics of the knee and the in situ forces in the anterior cruciate ligament, the anterior cruciate ligament graft, and the medial meniscus were measured. Anterior tibial translation significantly increased after anterior cruciate ligament transection, between 6.8 +/- 2.3 mm at full extension and 12.6 +/- 3.3 mm at 30 degrees of flexion. Consequently, the resultant forces on the medial meniscus, ranging from 52 +/- 30 N to 63 +/- 51 N between full extension and 90 degrees of knee flexion in the intact knee, were doubled as a result of anterior cruciate ligament deficiency. However, after anterior cruciate ligament reconstruction, anterior tibial translations were restored to the levels of the intact knee, and thus the forces on the medial meniscus were restored as well. Likewise, the in situ forces in the anterior cruciate ligament replacement graft increased between 33% and 50% after medial meniscectomy.

Adult↗