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PubMed2005

Tensile engagement of the peri-ankle ligaments in stance phase.

BACKGROUND: Development of reconstructive operative procedures to restore normal ankle kinematics after injury requires an understanding of the biomechanics of the ankle during gait. The contribution of the peri-ankle ligaments to ankle motion control is not yet well understood. Knowledge of the tensile engagement of the peri-ankle ligaments during stance phase is necessary to achieve physiologic motion patterns. METHODS: Eleven fresh-frozen cadaver ankles were subjected to a dynamic loading sequence simulating the stance phase of normal level gait. Simultaneously, ligament strain was continuously monitored in the anterior talofibular, calcaneofibular, and posterior talofibular ligaments, as well as in the anterior, middle, and posterior superficial deltoid ligaments. Eight of these specimens underwent further quasi-static range-of-motion testing, where ligament tension recruitment was assessed at 30 degrees plantarflexion and 30 degrees dorsiflexion. RESULTS: In the dynamic loading tests, none of the ligaments monitored showed a reproducible strain pattern indicating a role in ankle stabilization. However, in the extended range-of-motion tests, most ligaments were taut in plantarflexion or dorsiflexion. CONCLUSIONS: A consistent combination of individual ligament strain patterns that principally control ankle motion was not identified; none of the ligaments studied were reproducibly recruited to be a primary stabilizing structure. The peri-ankle ligaments are likely to be secondary restraining structures that serve to resist motion to avoid extreme positions. Stance phase ankle motion appears to be primarily controlled by articular congruity, not by peri-ankle ligament tension.

Aged↗
PubMed2006

Anatomy of ligamentous structures in the tarsal sinus and canal.

BACKGROUND: The descriptive morphology of the interosseous talocalcaneal ligament and other structures in the tarsal sinus and canal vary. An anatomical investigation of the ligamentous structures in the tarsal sinus and canal identified two distinct ligaments, the interosseous talocalcaneal ligament and the anterior capsular ligament, and three components of the medial root of the inferior extensor retinaculum. METHODS: Forty embalmed cadaver feet were examined. After disarticulation of the ankle joint, the posterior half of the talus was removed. The length, width, and thickness of the two ligaments and the three components of the extensor retinaculum in the tarsal canal and sinus were measured with calipers. Anatomical variations were recorded. RESULTS: The interosseous talocalcaneal ligament was band-like in 92.5% (38 of 40) of examined specimens, and the anterior capsular ligament was present in 95% (39 of 40) of specimens. The interosseous talocalcaneal ligament, the medial component of the inferior extensor retinaculum, and the talar component of the inferior extensor retinaculum had one or two distinct anatomical variations of morphology and attachments. The interosseous talocalcaneal ligament and the medial component of the extensor retinaculum formed a V shape in the tarsal sinus and canal. CONCLUSION AND CLINICAL RELEVANCE: We demonstrated the morphology and dimensions of the ligaments and components of the extensor retinaculum in the tarsal sinus and canal. Precise anatomy of the structures in the tarsal sinus and canal will strengthen our understanding of their function in the motion or stabilization of the subtalar joint. There may be a functional link between the medial component of the inferior extensor retinaculum and the interosseous talocalcaneal ligament.

Aged↗
PubMed2006

Magnetic resonance imaging of the craniocervical junction at 3-T: observation of the accessory atlantoaxial ligaments.

OBJECTIVE: Instability of the craniocervical junction can cause neurological sequelae or pain. Stability of this region depends on extensive ligamentous support structures, most of which are well studied by magnetic resonance imaging (MRI) scanning. Although the contribution of the accessory atlantoaxial ligament to rotational stability has been described, this ligament has not been identified by imaging. Therefore, we investigated the imaging characteristics of this ligament and its relationship to the ligamentous complex of the craniocervical junction using the high resolution offered by 3-T MRI scans. METHODS: Ten healthy volunteers underwent MRI scanning at 3-T to determine the normal anatomy of this ligament. RESULTS: The atlantoaxial (C1-C2) segment of the ligament was identified in all 10 subjects bilaterally and symmetrically. Its mean dimensions were 2.8 x 1.8 mm. In four out of 10 subjects, the occipitoatlantal (C0-C1) segment was observed. At this level, the mean dimensions of the ligament were 1.6 x 1.2 mm on the right and 1.8 x 1.4 mm on the left. Its size varied between the right and left sides. CONCLUSION: The accessory atlantoaxial ligament can be visualized using high-resolution MRI scans at 3-T. The ligament was most consistent and robust at C1-C2. The ligament may, therefore, contribute to rotational stability at this level. Future studies will determine the biomechanical importance of this ligament, especially in the setting of trauma.

Adult↗
PubMed1987

Sensory innervation of the periodontal ligament in the incisor and molar of the monkey, Macaca fuscata. An immunohistochemical study for neurofilament protein and glia-specific S-100 protein.

Nervous elements in the periodontal ligament of the monkey, Macaca fuscata were investigated by means of immunohistochemistry for neurofilament protein (NFP) and S-100 protein. Thick nerve bundles with NFP-immunoreactivity entered the periodontal ligament through slits at the bottom of the alveolar socket, whereas thinner bundles, also NFP-immunoreactive, penetrated the ligament from the lateral wall of the alveolar socket. The NFP-immunopositive nerve fibers were densely distributed around the root apex in both incisors and molars. In the upper incisors, another dense distribution of NFP-positive nerves was found in the apical half of the lingual periodontal ligament and in the coronal half of the labial periodontal ligament. The periodontal nerve fibers in the incisors ramified in a dendritic fashion, terminating as free nerve endings within the periodontal ligament. Immunostaining for S-100 protein demonstrated the Schwann sheaths of nerves which showed the same distribution pattern as that of the NFP-immunopositive fibers in the periodontal ligament of the incisors. In molars, immunostaining for NFP and S-100 showed that nerves were numerous in the apical region of the periodontal ligament. However, NFP-immunopositive nerves were fewer than the S-100-positive nervous elements in the apical region in molars. This discrepancy suggests the presence of NFP-immunonegative nerves. Immunostaining for S-100 is thus useful for demonstration of neural elements in the periodontal ligament of molars. The S-100-immunoreactive neural elements in the periodontal ligament were more numerous in incisors than in molars. In addition to the free nerve endings, a small population of coiled nerve endings was observed in the periodontal ligament of molars. Most of the nerve fibers and cell bodies in the trigeminal ganglion showed NFP-immunoreactivity, whereas all in the mesencephalic nucleus of the trigeminal nerve were negative in NFP-reaction. This finding suggests that the periodontal ligament of molars receives a dual innervation from the trigeminal ganglion and mesencephalic nucleus.

Animals↗
PubMed2001

Ligamentous stabilizers against posterolateral rotatory instability of the elbow.

BACKGROUND: The lateral ulnar collateral ligament, the entire lateral collateral ligament complex, and the overlying extensor muscles have all been suggested as key stabilizers against posterolateral rotatory instability of the elbow. The purpose of this investigation was to determine whether either an intact radial collateral ligament alone or an intact lateral ulnar collateral ligament alone is sufficient to prevent posterolateral rotatory instability when the annular ligament is intact. METHODS: Sequential sectioning of the radial collateral and lateral ulnar collateral ligaments was performed in twelve fresh-frozen cadaveric upper extremities. At each stage of the sectioning protocol, a pivot shift test was performed with the arm in a vertical position. Passive elbow flexion was performed with the forearm maintained in either pronation or supination and the arm in the varus and valgus gravity-loaded orientations. An electromagnetic tracking device was used to quantify the internal-external rotation and varus-valgus angulation of the ulna with respect to the humerus. RESULTS: Compared with the intact elbow, no differences in the magnitude of internal-external rotation or maximum varus-valgus laxity of the ulna were detected with only the radial collateral or lateral ulnar collateral ligament intact (p > 0.05). However, once the entire lateral collateral ligament was transected, significant increases in internal-external rotation (p = 0.0007) and maximum varus-valgus laxity (p < 0.0001) were measured. None of the pivot shift tests had a clinically positive result until the entire lateral collateral ligament was sectioned. CONCLUSIONS: This study suggests that, when the annular ligament is intact, either the radial collateral ligament or the lateral ulnar collateral ligament can be transected without inducing posterolateral rotatory instability of the elbow.

Aged↗
PubMed1999

MR imaging findings of lateral ulnar collateral ligament abnormalities in patients with lateral epicondylitis.

OBJECTIVE: The purpose of this paper was to use MR imaging to determine whether a relationship exists between lateral epicondylitis and abnormalities of the lateral ulnar collateral ligament. SUBJECTS AND METHODS: The study group comprised 35 consecutive patients who were referred for MR imaging to rule out lateral epicondylitis. On MR imaging, "lateral epicondylitis" was defined as increased signal intensity of the extensor tendons close to their insertion on the lateral epicondyle. The severity of the lateral epicondylitis was graded as mild, moderate, or severe. The origin of the lateral collateral ligamentous complex was characterized, and the lateral ulnar collateral ligament was graded as normal, thickened, partially torn, or torn. Eleven patients underwent elbow surgery after the initial MR examination. RESULTS: In 15 patients, MR imaging revealed characteristics of mild lateral epicondylitis. In 13 of these patients, the lateral ulnar collateral ligament was normal; one patient showed a thickened ligament; and one patient had a thinned ligament. In 11 patients, MR imaging showed features of moderate lateral epicondylitis. In eight of these patients, the lateral ulnar collateral ligament was thickened, and in the remaining three patients the ligament was normal. All nine patients with severe lateral epicondylitis showed abnormalities of the lateral ulnar collateral ligament on MR imaging. In one of these patients the lateral ulnar collateral ligament was thickened, in three patients we saw a partial tear, and in the remaining five patients we saw a complete tear of the ligament. CONCLUSION: In our study, MR imaging features of lateral epicondylitis were often associated with thickening and tears of the lateral ulnar collateral ligament.

Adult↗
PubMed1989

[Optimal treatment of complex ligament injuries and biomechanical aspects].

Certain guidelines may be established for surgical treatment of complex lesions of genicular ligaments. Preferential treatment should be given to the central stabilizers, anterior and posterior cruciate ligaments. Suturing with autologous augmentation is the rule for the anterior cruciate ligament, whereas the posterior cruciate ligament should be stabilised by both suturing and relief, using a transosseous PDS cord. The main peripheral ligaments, internal and external ligaments as well as arcuatum complex, have to be sutured, once instability has been confirmed. In cases of complex injuries, lateral structures are more important than median peripheral structures. Sutures should be tied for good stability. Non-absorbable material is used in cases in which stability of anchorage should enable no-plaster after-care. Sutured ligaments should be tension-adjusted close to stretching position (Lachman position, for main ligaments) and with neutral rotation. Sutures in shortened position may undergo rupture and thus jeopardize suturing at all. Only sutures for the posterior cruciate ligament should be strained close to rectangular position, since this actually represents maximum tension of the posterior cruciate ligament. Knee joint luxation is usually based on damage to all three ligaments, though two-ligament injuries are possible. Surgery is the optimum approach, since it is the only way to accomplish mechanically favourable adaptation of the central stabilizers.

Biomechanical Phenomena↗
PubMed1988

[Experimental study on ossification of spinal ligaments in the rabbit under influence of bone morphogenetic protein].

Bone morphogenetic protein (BMP) is known to induce cartilage from mesenchymal cells in organ culture. The purpose of the present study was to determine whether spinal ligaments differentiate into cartilage when cultured with BMP. Implantation of BMP into the yellow ligament was also done to make a model of the ossification of yellow ligament. The rabbit was employed as an experimental animal. In organ culture, BMP induced new cartilage from the posterior longitudinal ligament, the yellow ligament and the supraspinous ligament. This indicates that spinal ligaments have the potential to ossify, and bone or periosteum may not have a direct relationship with spinal ligament ossification. Ossification of the yellow ligament was produced by implantation of BMP. Blood vessels are thought to have some role in the ossification of spinal ligaments. The spinal cord was compressed posteriorly by the ossified yellow ligament. This ossification of the yellow ligament resembled that of human beings and may be regarded as a useful experimental model.

Animals↗
PubMed1988

[Variations in the calcaneo-fibular ligament (lig. calcaneofibulare). Application to the kinematics of the ankle].

The authors observe variations in the calcaneo-fibular ligament because this ligament controls two articulations, the talo-crural and the subtalar. This study is based on the dissection of the ankle of 20 specimens. The calcaneo-fibular ligament is reinforced by the ventral and lateral talo-calcaneus ligaments with variations. 3 types of disposition have been described. Type A: A lateral talo-calcaneal ligament reinforces the calcaneo-fibular ligament. These two ligaments are divergent on the proximal, medial, or distal part. Type B: There is an independent lateral talo-calcaneal ligament forward of the calcaneo-fibular ligament. Type C: A ventral talo-calcaneal ligament is observed, parallel to the interosseous ligament. The authors consider the consequences of variation in the lateral ligaments of the ankle for the functioning of the tibio-tarsal articulation, the subtalar articulation and the astragalo-scaphoid articulation in order to propose specific radiographic examination of the kinematics of the ankle.

Ankle Joint↗
PubMed1985

On the interpretation of our anterior cruciate ligament data.

Design of a synthetic replacement or selection of a biologic substitute requires detailed knowledge of the mechanical properties of the normal ligament. Femur-anterior cruciate ligament-tibia unit (ACL) data have been frequently used for this purpose, although not always properly. Mechanical properties of the human ACL-bone unit are reviewed. Ligament stiffness, elongation, and energy results are based on grip-to-grip motion and thus include ligament and limited bone deformations. Maximum bone-ligament-bone force in young donors (1730 +/- 66N) is higher than reported previously and represents only ligamentous failures. Methods for measuring tissue dimensions are provided and must be duplicated for obtaining accurate material property data. Bone-ligament-bone strain data are higher than those in reports where midsubstance collagen strains are measured and differ from data obtained on isolated ligaments. The authors have examined many factors that affect ligament-bone unit response. Increasing age weakens the tissue-bone preparation, and only when testing is performed at high rates will ligamentous failures predominate. Use of the authors' data in prosthetic ligament evaluation requires that the material be selected based on ligament bundle properties, the prosthesis be examined under similar testing conditions, and anticipated functional loads and margins of safety be determined.

Humans↗
PubMed1996

The spatiotemporal development of innervation in spinal ligaments of chickens.

The development of the innervation of both central and lateral (intertransverse) spinal ligaments was investigated in chickens between the time of hatching and 13 wk of age. A total of 36 White Leghorn chickens in 4 groups of 9 at ages 0, 2, 7, and 13 wk were used. The spinal ligaments were dissected, serially sectioned and labelled with a monoclonal antibody against neurofilament protein and observed using either conventional fluorescence or confocal microscopy. Only a few nerve elements were found in the ligaments at hatching and these consisted simply of single nerve fibres and small nerve bundles. The number of nerve elements increased rapidly up to 7 wk of age when large nerve bundles and Ruffini corpuscles were also found. The number of nerve elements decreased between 7 and 13 wk birds when the ligaments had begun to ossify and the amount of collagenous ligamentous tissue was significantly reduced. The fluctuation in numbers of neural elements was due to changes in numbers of single nerve fibres and small nerve bundles rather than large nerve bundles and Ruffini corpuscles which remained constant. In contrast to this significant increase in numbers of nerve elements, the innervation density of the ligaments decreased because of the overwhelming increase of the ligament volume due to growth. There were no differences between ligaments on the left and right sides of the body, but there was an unequal distribution of the neural elements within the ligaments; most were found in the cranial third of the intertransverse ligaments. These results show that significant changes in innervation of spinal ligaments occur during development and reflect the possibility that damage to the ligaments during this time could produce significant and permanent damage, especially in relation to the maintenance of an erect spine.

Animals↗
PubMed1997

Correlation between ossification of the stylohyoid ligament and osteophytes of the cervical spine.

OBJECTIVE: To investigate the correlation between ligamentous ossification or osteophytes of the cervical spine and ossification of the styloid process and stylohyoid ligament, and to determine any relation between diffuse idiopathic skeletal hyperostosis (DISH) of the thoracic spine and ossification of the styloid process and stylohyoid ligament. METHODS: Four patients having cervical spine DISH, an elongated styloid process and/or variable patterns of stylohyoid ligament ossification, and clinical findings compatible with Eagle's syndrome are described. Cervical computed tomography scans of 100 patients who also had lateral radiographs of the thoracic spine were reviewed. Point biserial and Spearman rank correlation analysis, McNemar test, chi-squared test, and Fisher's exact test were used to determine correlation between elongation of the styloid process and/or ossification of the stylohyoid ligament and (1) ligamentous ossification or osteophytes of the cervical spine (the characteristic spinal manifestation of DISH), and/or (2) DISH of the thoracic spine. RESULTS: (1) Elongation of the styloid process and variable patterns of ossification of the proximal, middle, and distal parts of the stylohyoid ligament, and (2) enlargement of this ligament were significantly correlated with transverse and anteroposterior dimensions of ligamentous ossification or osteophytes of the cervical spine at various levels. The prevalence of such abnormalities of this process and ligament was not significantly different between the patients with and without thoracic spine DISH. CONCLUSION: Variable types of styloid process-stylohyoid ligament complex abnormalities have significant correlation with ligamentous ossification and osteophytes of the cervical spine.

Aged↗
PubMed1995

Increased expression of the beta 1, alpha 5, and alpha v integrin adhesion receptor subunits occurs coincident with remodeling of stress-deprived rabbit anterior cruciate and medial collateral ligaments.

The biomechanical, biochemical, and morphological properties of the anterior cruciate and medial collateral ligaments are dramatically altered in response to deprivation of normal physical forces and joint motion. Integrin adhesion receptors are known to play important roles in the tissue remodeling that occurs in the course of normal wound repair. We propose that integrins play a similar role in the remodeling of the extracellular matrix in stress-deprived periarticular ligaments. This study tests the hypothesis that altered expression of integrins on ligament fibroblasts accompanies this remodeling. The left knees of 15 New Zealand White rabbits were surgically immobilized in acute flexion and the right knees served as controls (no operation). The anterior cruciate and medial collateral ligaments were harvested at 1, 3, 5, 9, or 12 weeks after immobilization. Sections from the ligaments were immunostained with monoclonal antibodies specific for the integrin subunits beta 1, alpha 5, alpha 6, and alpha v, as well as with a negative control antibody. Fibroblasts within both the stress-deprived anterior cruciate and medial collateral ligaments demonstrated markedly increased staining for the beta 1, alpha 5, and alpha v subunits, as compared with the controls. The increased staining was greatest at 9 weeks in the anterior cruciate ligament and at 12 weeks in the medial collateral ligament. Western blot study of ligament proteins extracted with sodium dodecyl sulfate demonstrated an increased amount of beta 1 subunit protein in both ligaments from knees that were stress deprived for 9 and 12 weeks, as compared with the control ligaments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1997

An inverse dynamics modeling approach to determine the restraining function of human knee ligament bundles.

During knee motion, the fiber bundles of ligaments are nonuniformly loaded in a recruitment pattern which is different for successive knee-joint positions. As a result, the restraining functions of these ligaments are variable. To analyze the relative restraint contributions of the fiber bundles in different knee-joint positions, a new method was developed. Its application was illustrated for the cruciate ligaments of one knee-joint specimen. The methods developed to estimate bundle forces comprise five steps. First, the three-dimensional motions of a knee specimen are measured for anterior-posterior forces, using Röntgen Stereophotogrammetric Analysis. Second, bone-ligament-bone tensile tests are performed to evaluate the mechanical properties of these structures in several relative orientations of the bones. Third, multiple fiber bundles are identified in each ligament, based on the main fiber orientations. Fourth, the nonlinear force-length relationship of each functional bundle, as defined by a stiffness and a recruitment parameter, is determined by combining the multidirectional tensile tests with a multiline-element ligament model. Finally, the information obtained is combined in a whole-joint computer model of the knee, to determine the internal forces in the initial kinematic experiment, using an inverse dynamics approach. The technique appeared to be extremely time consuming and technologically involved. However, it was demonstrated to be useful and effective. The preliminary results reveal that the fiber bundle restraints are extremely sensitive to the knee flexion angle and the restraining forces are highly variable within the ligaments. For both cruciate ligaments, a gradual transition was demonstrated in load transfer from the posterior bundles to the more anteriorly positioned ones during knee flexion. Furthermore, it appeared that relatively high forces were carried by only a few fiber bundles at each flexion angle. Based on these preliminary results, it is concluded that the determination of forces in multiple ligament bundles is important for the understanding of failure mechanisms of ligaments. In particular, alternate loading of different fiber bundles suggests that successful operative reconstruction of the cruciate ligaments may not be achieved simply by a one-bundle preparation.

Algorithms↗
PubMed2002

The cellular networks of normal ovine medial collateral and anterior cruciate ligaments are not accurately recapitulated in scar tissue.

The purpose of this study was to characterize the cellular organization of the ovine medial collateral ligament (MCL) and anterior cruciate ligament (ACL) and compare this organization with that found in ligaments undergoing healing. Indirect immunofluorescence microscopy, used in combination with antibodies to cytoskeletal proteins, was employed to visualize individual ligament cells. Normal ligaments contained fusiform cells arranged in rows, which were stacked at regular intervals across the body of the ligament forming a three-dimensional cellular lattice. Each cell exhibited prominent cytoplasmic processes that extended for long distances through the extracellular matrix to adjacent cells, and these processes contained gap junctions. Thus the cells in rows and between rows were interconnected. The cells of the MCL and ACL scars were also arranged in rows, but these rows were shorter, irregularly arranged and closely packed into bundles resulting in tissue with a higher cellular density. In addition, cells transiting the cell cycle were detected in the scar but not in normal ligament. While the rows of cells in the normal ligament extended along the long axis of the ligament, the bundles of rows of ligament scar cells had a random orientation with respect to one another and to the region outside the scar. Over time both the ACL and the MCL scars displayed discontinuities in their cellular rows. In contrast to the scars of the MCL, which contained discontinuities filled with cellular projections and gap junctions, ACL scars contained discontinuities that were devoid of cells and gap junctions. These discontinuities as well as the differences between normal and scar cytoarchitecture may represent features of an inadequate healing response and/or may provide the structural basis for the altered biomechanics of healing ligaments.

Animals↗
PubMedDate not supplied

Reproducibility of anatomic tibial landmarks for anterior cruciate ligament reconstructions.

We evaluated the reproducibility of landmarks used for accurate anatomic placement of the tibial tunnel in anterior cruciate ligament reconstruction. Landmarks evaluated were the medial tibial eminence, the posterior cruciate ligament, the "over-the-back" position, the true posterior border of the tibia, and the posterior border of the lateral meniscus. Forty-two pairs of cadaveric knees were dissected, and anatomic measurements were made regarding the anterior cruciate ligament insertion and these various landmarks. Statistical analysis was used to confirm reproducibility and significance. Measurements based on the medial tibial eminence and posterior border of the meniscus were particularly erratic. The most reproducible anatomic landmark was the posterior cruciate ligament. The anterior border of the posterior cruciate ligament was consistently 6.7 mm posterior to the posterior border of the anterior cruciate ligament and 10.9 mm posterior to the central sagittal insertion point of the anterior cruciate ligament. The over-the-back position was consistently in contact with the anterior border of the posterior cruciate ligament if the knee was flexed with a posterior-directed force applied. In this position, the over-the-back position was equally reproducible as compared with the posterior cruciate ligament. Measurements gauged from the true posterior border of the tibia gave a second rigid bony landmark but with a wider standard deviation than the posterior cruciate ligament-based landmarks. The relative anterior-posterior dimension of the tibia did not correlate with the relationship between the anterior cruciate ligament and other anatomic landmarks.

Anterior Cruciate Ligament↗
PubMed1995

Response of immature diabetic rat bone-ligament junctions to insulin and exercise.

The mechanical and morphological characteristics of femur-medial collateral ligament-tibia units and the histomorphometry of medial collateral ligament-tibial insertion were examined in female Sprague-Dawley rats with diabetes mellitus (type I, insulin-dependent diabetes). Diabetes was induced with the streptozotocin, a drug with toxic effects on insulin-producing islet cells in the pancreas. The groups studied included rats with untreated streptozotocin-induced diabetes mellitus (Diabetes), insulin-treated streptozotocin-induced diabetes (Diabetes-Insulin), exercise with streptozotocin-induced diabetes (Diabetes-Exercise), exercise with insulin-treated streptozotocin-induced diabetes (Diabetes-Insulin-Exercise), and age-matched sedentary-control rats (Control). Diabetes and Diabetes-Exercise groups had significantly lower body mass and higher blood glucose than Diabetes-Insulin, Diabetes-Insulin-Exercise, and Control groups, indicating that exercise alone did not prevent growth retardation or improve blood glucose control in the streptozotocin-induced diabetes. The strength of Diabetes femur-medial collateral ligament-tibia units was significantly less than Control, but exercise (with or without insulin treatment) maintained the bone-ligament-bone unit strength at a normal level. The load (per unit body mass) of Diabetes-Exercise femur-medial collateral ligament-tibia unit was significantly greater than Control, Diabetes, and Diabetes-Insulin groups. The tensile stiffness (per unit body mass) of the femur-medial collateral ligament-tibia unit for the Diabetes-Exercise group was also significantly greater than Control and Diabetes-Insulin groups. The fibroblast-like cell density in medial collateral ligament at its tibial-insertion site and medial collateral ligament insertion area was significantly less in Diabetes rats. RELEVANCE--:Diabetes mellitus can have deleterious effects on connective tissues, such as bone and ligament. Thus the bone-ligament junction becomes vulnerable. The results of this experiment suggest, however, that exercise, with or without insulin treatment, can have a positive effect on the bone-ligament interface in the rat with type I diabetes mellitus. Furthermore exercise (with insulin treatments) can mitigate growth retardation and many of the adverse effects of streptozotocin-induced diabetes on the structure and mechanical properties of immature bone-ligament junctions.

Journal Article↗
PubMed1998

The mechanical properties of human alar and transverse ligaments at slow and fast extension rates.

OBJECTIVE: To study biomechanics and failure characteristics of the alar and transverse ligaments of the upper cervical spine at two different extension rates. DESIGN. IN VITRO: biomechanical study using human and alar and transverse ligament specimens. BACKGROUND: Previous studies of these ligaments have been at relatively slow extension rates, even though the real life trauma occurs at significantly higher extension rates. METHODS: Fresh human cadaveric alar and transverse ligaments were subjected to slow (0.1 mm/s) and then fast (920 mm/s) extension rates. Force and elongation curves were recorded during the testing, and several biomechanical parameters were computed and compared. First the specimen was stretched at the slow extension rate up to 70 N for the alar ligament and 140 N for the transverse ligament. Then the specimens were stretched until failure at the fast extension rate. RESULTS: Average initial lengths of the alar and transverse ligaments were 11.2 and 18.0 mm, respectively. At 70 N, the average alar ligament strain decreased from 16.4 to 0.3%, the stiffness increased from 80 to 2316 N/mm and the energy absorbed decreased from 47.4 to 1.3 Nmm, as the extension rate increased from the slow to the fast. At failure, the average strain, force and energy absorbed at the fast extension rate were respectively 3.1%, 367 N and 123 Nmm. For the transverse ligament at 140 N, the strain decreased from 12.5 to 0.6%, the stiffness increased from 141 to 1472 N/mm, and the energy absorbed decreased from 96.1 to 7.6 Nmm as the extension rate went from slow to the fast. At failure, strain, force and energy absorbed for the transverse ligament at the fast extension rate were, respectively, 2.3% and 436 N and 101 Nmm respectively. CONCLUSION: Within the physiological limits, the strain and energy absorbed decreased to less than one tenth, while the stiffness increased to greater than ten times as the extension rate increased, for both the alar and transverse ligaments. When failed at the faster rate, the alar ligament, although weaker of the two, absorbed greater energy to failure because of its higher failure strain.

Journal Article↗