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At least 937 records · Page 52Linked to original sources
PubMed1993

The relationship between the rotation possibilities between femur and tibia and the lengths of the cruciate ligaments.

The system of the anterior (a) and posterior (p) cruciate ligaments and their distances between attachments to the femur (f) and tibia (t), respectively, as found in the knee joint of tetrapods is considered as a crossed four-bar linkage. Starting from a flat or curved tibial articulating surface the shape of the femoral articulating surfaces in principle can be derived (Huson, 1974; Menschik, 1974). The point of intersection (S) of the cruciate ligaments is the instantaneous centre of rotation and describes a curve during knee angulation; the centrode. Two centrodes are distinguished: S1 with the tibia stationary and S2 with the femur stationary. During leg bending the centrodes roll over each other, without sliding. Four series of knee-joint simulations were made. In series A, the femoral bar (distance between cruciate ligaments) was varied, in series B, the anterior cruciate ligament (so the length of a ligament). In series C and D, combinations of bar lengths were varied. The maximum leg rotation range was calculated from the lengths of the bars of the cruciate ligament system for each of the series A ... D. Also the leg rotation range for which the knee joint is mechanically stabilized by the cruciate ligaments was calculated. The stabilization criterium chosen was that a cruciate ligament may not become perpendicular (> 78.5 degrees) to the articulating surfaces. It was found that the cruciate ligaments alone cannot stabilize the knee joint adequately over the whole required range of leg movement. External structures are required to obtain full stabilization. As the femoral and tibial articulating surfaces never lie at the centrodes, considerable sliding occurs between them. It is suggested that a uniformly distributed sliding is essential for lubrication and so for a proper knee-joint functioning.

Animals↗
PubMed1984

Healing of experimental ligament rupture: findings by scanning electron microscopy.

The medial collateral ligaments of the knee joints of 16 rats were cut. Sixteen ligaments were allowed to heal spontaneously while the others were immediately sutured under the microscope. Four sham-operated immobilized rats served as controls. The ligamentous healing was registered after 4-5 weeks of immobilization under a scanning electron microscope (SEM). In the control ligaments, collagen bundles of variable thickness were observed as the main supporting elements. Numerous thin fibers were seen between the bundles. The surgically corrected ligaments showed a microstructural picture often difficult to distinguish from the controls. The unsutured ligaments, however, showed a much more variable picture. In some unsutured cases ligamentous regeneration was blocked by extensive scar formation. In many unsutured cases, however, signs of ligamentous regeneration were observed. It was noted that the SEM is a useful and sophisticated tool for studies on ligament healing.

Animals↗
PubMed1994

Anatomical and biomechanical characteristics of human meniscofemoral ligaments.

The meniscofemoral ligaments (MFL) of 26 human cadaver knees were studied to determine their structural importance. The incidence of at least one MFL in each of the specimens studied was 100%, and 46% of the specimens had both MFL ligaments (Humphry and Wrisberg). Another 23% had a single Humphry ligament, and the remaining 31% had a single Wrisberg ligament. A laser micrometer system was used to measure cross-sectional shape and area. The average cross-sectional areas of the Humphry and Wrisberg ligaments were 7.8 +/- 4.7 mm2 and 6.7 +/- 4.1 mm2, respectively. In specimens with both a Humphry and Wrisberg ligament, the larger ligament area was on average 100% greater than the smaller ligament area. The average ratios of the cross sectional areas of Wrisberg and Humphry to that for the PCL within the same knee were 12.0% +/- 7.7% and 11.9% +/- 5.7%, respectively. The structural properties of the MFL bone-ligament-meniscus complex and the mechanical properties of the MFL midsubstance were determined by uniaxial tensile testing. The average stiffness, ultimate load, and energy absorbed at failure were, respectively, 49.0 +/- 18.4 N/mm, 297.4 +/- 141.4 N and 1125.4 +/- 735.8 N/mm. The tangent modulus between 4% and 7% strain was 355.1 +/- 234.0 MPa. Our findings suggest that the MFL is a significant biomechanical structure in the knee because of its size, stiffness, and strength.

Adult↗
PubMed1999

[Lateral ankle ligament rupture. When is surgical management indicated and when conservative therapy preferred?].

In lateral ankle ligament tears, the anterior talofibular ligament ruptures most commonly, often in conjunction with the calcaneofibular ligament. The posterior talofibular ligament is rarely affected. Associated injuries at the adjacent ligamentous structures or at the articular cartilage of the ankle commonly occur. The diagnosis is established clinically with the anterolateral drawer sign and an increased lateral talar tilt. Stress radiographs in two planes demonstrate talar tilt and anterior displacement of the talus, in comparison to the unaffected side. Magnetic resonance imaging provides an early diagnosis of concomitant injuries. Simple, acute lateral ankle ligament tears are treated non-operatively. Surgery is indicated in dislocated bone avulsions and in chondral or osteochondral fractures. A recurrent tear in an athletic patient should also be treated operatively. Athletic endeavours, the number of torn ligaments and patient age are no useful indicators for surgical treatment. Conservative treatment consist of oedema therapy, immobilization of the fibular ligaments with as little compromise of ankle joint function as possible, and rehabilitation with muscle strengthening and proprioception training. During surgery, the ligament stumps are reapproximated in anatomic position, reinforced with local tissue if necessary, and the articular surface is examined for concomitant injuries.

Adolescent↗
PubMed1998

The immediate postoperative kinematic state after anterior cruciate ligament reconstruction with increasing peroperative tension.

The last steps in anterior cruciate ligament (ACL) reconstruction are tensioning and fixation of the ligament. However, how much tension should be applied to the ligament in general or in each individual and in which position the ligament should be fixed remain unanswered questions. The purpose of this study was to investigate the effect of increasing ligament tension on the immediate postoperative kinematic state of the ACL-reconstructed knee. Nine cadaver knees were mounted in a mechanical measuring device based on a redesign of the Genucom knee testing system, so that the femur was fixed to a force plate and the moving tibia to a goniometer arm for registration of movement. The ligament was attached on the tibial side to a Kistler load cell and a turn-buckle for adjustment of ligament tension. The ligament was tensioned at 30 degrees of flexion with 5, 33, 66, 99 and 132 N. The cadaver knees were tested with an intact ACL, after sacrifice of the ACL and after reconstruction of the ACL with an ABC ligament. Results showed that there was a significant decrease in knee motion when the tension was higher than 33 N. This resulted in an overconstrained knee with less anteroposterior translation, internal-external rotation and varus-valgus movement compared with the uninjured knee.

Anterior Cruciate Ligament↗
PubMed2006

Relationship of the uterosacral ligament to the sacral plexus and to the pudendal nerve.

We describe the anatomy of the uterosacral ligament with respect to the sacral plexus. In six adult female embalmed cadavers, we identified the uterosacral ligament and its lateral nerve relations. Using the ischial spine as the starting point and measuring along the axis of the uterosacral ligament, we noted that the S1 trunk of the sacral plexus passes under the ligament 3.9 cm [95% confidence interval (CI), 2.1-5.8 cm] superior to the ischial spine. The S2 trunk passes under the ligament at 2.6 cm (95% CI; 1.5, 3.6 cm), the S3 trunk passes under the ligament at 1.5 cm (95% CI; 0.7, 2.4 cm), and the S4 trunk passes under the ligament at 0.9 cm (95% CI; 0.3, 1.5 cm) superior to the ischial spine. The pudendal nerve forms lateral to the uterosacral ligament. Our data demonstrate that the S1-S4 trunks of the sacral plexus, not the pudendal nerve, are vulnerable to injury during uterosacral ligament suspension.

Female↗
PubMed1998

Involvement of insulin-like growth factor I in development of ossification of the posterior longitudinal ligament of the spine.

In order to investigate the pathogenesis of ossification of the posterior longitudinal ligament (OPLL) of the spine, we examined the distribution of insulin-like growth factor I (IGF-I) in the posterior longitudinal ligaments of OPLL patients, and analyzed the effects of IGF-I on the cultured spinal ligament cells. For that purpose we established eight varieties of OPLL and non-OPLL cell lines obtained from spinal ligaments of corresponding patients, respectively. In contrast to non-OPLL cases, all the OPLL cases were histologically shown to contain round-shaped cartilage-like cells in the transitional region from preossifying to ossifying ligaments, and these cells were strongly stained with an antibody for IGF-I. In the vicinity of preossifying cartilaginous tissues, ligament cells also had a rod-like appearance and were positive for IGF-I immunohistochemically. The effects of IGF-I on cultured spinal ligament cells were assayed by alkaline phosphatase (AP) activity, DNA synthesis, and the amounts of collagen produced. The number of OPLL cell lines that increased AP activity, responding to IGF-I irrespective of 1,25(OH)2D3, was significantly larger than that of non-OPLL cell lines, although IGF-I stimulated DNA and procollagen type I carboxyl-terminal peptide synthesis in most of both OPLL and non-OPLL cell lines. These data demonstrate the dominant expression of IGF-I in the posterior longitudinal ligaments of OPLL patients, and suggest that IGF-I preferentially induces osteogenic differentiation in OPLL cells rather than in non-OPLL cells. IGF-I, therefore, may be involved in the local ossification process of spinal ligaments observed in OPLL patients.

Adult↗
PubMed2002

MRI assessment of the alar ligaments in the late stage of whiplash injury--a study of structural abnormalities and observer agreement.

Our aim was to characterise and classify structural changes in the alar ligaments in the late stage of whiplash injuries by use of a new MRI protocol, and to evaluate the reliability and the validity of this classification. We studied 92 whiplash-injured and 30 uninjured individuals who underwent proton density-weighted MRI of the craniovertebral junction in three orthogonal planes. Changes in the alar ligaments (grades 0-3) based on the ratio between the high signal area and the total cross-sectional area were rated twice at a 4-month interval, independently by three radiologists. Inter- and intraobserver statistics were calculated by ordinary and weighted kappa. Cases classified differently were reviewed to identify potential causes for disagreement. The alar ligaments were satisfactorily demonstrated in all cases (244 ligaments in 122 individuals). The lesions, 2-9 years after the injury, varied from small high-signal spots to high signal throughout the cross-sectional area. Signal was highest near the condylar insertion in 82 of 94 ligaments, indicating a lesion near that insertion, and near the dental insertion in eight, indicating a medial lesion. No grade 2 or 3 lesion was found in the control group. At least two observers assigned the same grade to 214 ligaments (87.7%) on the second occasion. In 30 ligaments (12.3%) this agreement was not obtained. Pair-wise interobserver agreement (weighted kappa) was fair to moderate (0.31-0.54) in the first grading, improving to moderate (0.49-0.57) in the second. Intraobserver agreement (weighted kappa) was moderate to good (0.43-0.70). Whiplash trauma can cause permanent damage to the alar ligaments, which can be shown by high-resolution proton density-weighted MRI. Reliability of classification of alar ligament lesions needs to be improved.

Adolescent↗
PubMed1992

Mechanical properties of the human lumbar anterior longitudinal ligament.

A new technique incorporating a motion analysis system and a materials testing machine was used to investigate regional differences in the tensile mechanical properties of the lumbar spine anterior longitudinal ligament (ALL). Bone-ALL-bone specimens were prepared from young human cadaveric motion segments with no disc or bony pathology. Each specimen was distracted until failure at a constant crosshead displacement rate of 2.5 mm s-1 (approximately 1.0% strain per second). Strains were evaluated from digitized video recordings of markers attached to the ALL at 12 sites along its length and width, including the ligament substance and insertions. The 'overall' strain in the ligament was calculated from the outermost pairs of markers along the ligament length. The average tensile strength, the 'overall' tensile modulus and the 'overall' strain of the ALL at failure were 27.4 MPa (S.D. 5.9), 759 MPa (S.D. 336) and 4.95% (S.D. 1.51), respectively. Large and significant variations in the strains were present along the width and length of the ALL. Peak substance strains were over twofold greater than peak strains at the ligament insertion sites, whereas across the ligament width, peak strains in the outer portion of the ligament were over 40% greater than in the central region. Failure consistently occurred in the ligament mid-substance and ultimate strains at the ligament failure site averaged 12.1% (S.D. 2.3). These results indicate that the strains are highly nonuniform in the normal ALL.

Adult↗
PubMed1992

Stiffness of the ligaments of the human wrist joint.

In the present study the stiffness of the superficial ligaments of 14 human cadaver wrist joints have been determined. In these experiments the tested, fresh-frozen carpal joints are divided into a number of bone-ligament-bone complexes, which are loaded in a tensile testing machine at a rate of 66% of the ligaments' initial length per second to a maximal strain of 15%. From the force-elongation curves and ligament dimensions the tangent moduli for the ligament-bone strips are derived. The results show that, with regard to the tangent modulus, there is not a clear differentiation among ligament strips. Only the dorsal radiotriquetrum ligament (RTD) and the palmar radiocapitate ligament (RCP) appear to consist of a material of a relatively high tangent modulus, about 93 and 83 MPa, respectively. The other seven ligaments tested have similar tangent moduli, ranging from 25 to about 50 MPa.

Aged↗
PubMedDate not supplied

Experimental measurement of ligament force, facet force, and segment motion in the human lumbar spine.

Facet forces, longitudinal ligament loads, and vertebral body motion were experimentally measured in five fresh human lumbar spine segments, L1-L2. Strain gages on the bone surface were used to quantify facet loads. Buckle transducers were used to measure anterior and posterior longitudinal ligament loads. The three-dimensional motion of the motion segment was measured with an instrumented spatial linkage. The facets were found to carry no load in flexion, large loads during extension (205 N at a 10 Nm moment and a 190 N axial load), torsion (65 N at a 10 Nm moment and a 150 N axial load), and lateral bending (78 N at a 3 Nm moment and a 160 N axial load). The facet contact site on the inferior articular process of L1 was found to move inferiorly to a position of tip impingement near the lamina as extension moments increased. Impingement occurred in the range of 4-6 Nm extension. The posterior and anterior longitudinal ligaments were predominantly loaded in flexion and extension, respectively. No ligament loads occurred in lateral bending and torsion. A 1 cm strip of the anterior longitudinal ligament carried loads up to 130 N at the largest extension moment of 11.4 Nm. The posterior longitudinal ligament had a 60 N load at the largest flexion moment of 7.1 Nm. There was no pre-load in the ligament detectable with the buckle transducers (> 4 N). The facets and ligaments began carrying load immediately with applied load, without a lax region. The experimental technique developed and used provides a good tool for obtaining simultaneous facet joint loads, ligament loads, and vertebral body motion without altering the motion segment.

Adult↗
PubMed1993

An indirect method to assess wrist ligament forces with particular regard to the effect of preconditioning.

A method has been developed to calculate the forces that are developed in the ligaments of a joint specimen during motions. This indirect method is needed since direct measurements fail in the case of small ligaments. As an example the small ligaments of the carpal joint are considered. The rationale of the method is that the force generated in a ligament depends on the amount of strain to which it is subjected and on its material characteristics. In the method presented the lengths of the ligaments are determined in vitro at several joint positions by means of röntgenstereophotogrammetry. The zero-force length and the force-elongation relationship are determined on the same ligaments isolated in a materials testing machine. Over a considerable part of the strain range the measurement errors are relatively small compared to the forces determined, less than 10%. The method is applicable to joints in situations where other measuring methods cannot be used. The present analysis shows, however, that the force values determined are susceptible to preconditioning of the ligaments. In preconditioned ligaments the forces could be up to 50% lower than in the non-preconditioned situation. This suggests that ligament forces may vary considerably in vivo, depending on the extent of preconditioning provoked by a particular function.

Biomechanical Phenomena↗
PubMed1993

The isolated scapho-trapezio-trapezoid ligament injury. Diagnosis and surgical treatment in four cases.

Isolated injuries of the scapho-trapezial ligament complex are not well recognized. The ligament complex comprises the stout scapho-trapezial ligament, the floor of the flexor carpi radialis (FCR) tendon sheath and the scapho-capitate ligament. Between August 1991 and May 1992, we diagnosed and treated four cases of partial chronic post-traumatic lesions of this ligament complex. There was chronic pain at the base of the thenar eminence and instability of the thumb-index-middle finger pinch. Standard X-rays were normal. The diagnosis of ligament rupture was confirmed by mid-carpal arthrography showing filling of the sheath of FCR tendon. Surgical exploration showed complete rupture of the tendon sheath of FCR in two cases, associated in the other two cases with complete rupture of the scapho-trapezial ligament. Direct repair of the ligamentous elements was performed in all cases. The tendon of FCR was sutured to the tubercle of scaphoid to protect and to reinforce the ligament repair. The patients have been followed-up for between 6 and 12 months. All four patients recovered normal pinch strength to the middle finger. One patient suffered from chronic pain at work.

Humans↗
PubMed1990

The palmar radiocarpal ligaments: a study of adult and fetal human wrist joints.

The palmar radiocarpal ligaments were studied with use of fifty-four dissected adult cadaver wrists and serial sections on twenty-three wrists from fetuses ranging in size from 23 to 230 millimeters crown-rump length. Three palmar radiocarpal ligaments were clearly identified: the radioscaphocapitate, long radiolunate, and short radiolunate ligaments. The radioscaphocapitate ligament originates from the radial styloid process and inserts into the radial aspect of the waist of the scaphoid, hemicircumferentially around the distal pole of the scaphoid and interdigitates with fibers from the palmar aspect of the triangular fibrocartilage complex just palmar to the head of the capitate, with only a minor insertion distally into the body of the capitate. The long radiolunate ligament originates just ulnar to the radioscaphocapitate ligament, being separated from it throughout its course by the interligamentous sulcus. The long radiolunate supports, but is separate from, the palmar aspect of the scapholunate interosseous ligament, and inserts into the radial half of the palmar surface of the lunate. The short radiolunate ligament, previously not described, originates just palmar to the lunate facet of the distal radius articular surface and inserts as a flat sheet of fibers into the proximal margin of the palmar surface of the lunate. Each ligament is intracapsular, enveloped within a continuous superficial fibrous stratum and deep synovial stratum.

Adult↗
PubMed1994

Tensions in the palmar ligaments of the wrist. I. The normal wrist.

We developed a method for measurement of the in situ tensions in the ligaments of the palmar side of the wrist in cadaver specimens. The technique is based on deflecting the ligaments transversely (i.e., perpendicular to their longitudinal axis) using an instrumented probe. Based on measurement of the load required to deflect the ligament, magnitude of the transverse deflection, and axial length of the ligament, the axial tension in the ligament can be determined without otherwise disturbing it. The tensions in 8 palmar ligaments in 10 functional positions of the wrist in each of 5 fresh cadaver specimens were assessed. The position of the wrist was monitored, but the specimen was not loaded. We concluded that (1) the palmar ligaments are in tension, even with the wrist in neutral position and unloaded; (2) the following ligaments act as passive stabilizers: in neutral the triquetrocapitate and distal part of the radioscaphocapitate, in radial deviation the radiolunate, in ulnar deviation the ulnolunate, in pronation the proximal part of the radioscaphocapitate, in supination the ulnolunate, and in extension the ulnolunate, radiolunate, and radioscaphocapitate; (3) in any position some ligaments are in a state of greater tension than others. The radiolunate, ulnolunate, radioscaphocapitate had the greatest tension; and the lunotriquetral, trapeziocapitate, and scaphocapitate had the least.

Aged↗
PubMed2005

Effects of the posterior cruciate ligament reconstruction on the biomechanics of the knee joint: a finite element analysis.

BACKGROUND: Previous experimental studies have been conducted to evaluate the biomechanical effects of posterior cruciate ligament reconstruction; but no consensus has been reached on the preferred method of reconstruction. METHODS: The 3D finite element mesh of a knee joint was reconstructed from computed tomography and magnetic resonance images. The ligaments were considered as hyperelastic materials. The tibiofemoral and patellofemoral joints were modeled with large sliding contact elements. The 3D model was used to simulate knee flexion from 0 degrees to 90 degrees in four cases: a knee with a "native" posterior cruciate ligament, a resected posterior cruciate ligament, a reconstructed single graft posterior cruciate ligament, and a reconstructed double graft posterior cruciate ligament. FINDINGS: A resected posterior cruciate ligament induced high compressive forces in the medial tibiofemoral and patellofemoral compartments. The pressures generated in the tibiofemoral and patellofemoral compartments were nearly the same for the two reconstruction techniques (single graft and double graft). The single graft resulted in lower tensile stresses inside the graft than for the double graft. INTERPRETATION: Firstly, a resected posterior cruciate ligament should be replaced to avoid excessive compressive forces, which are a source of cartilage degeneration. Secondly, the two types of posterior cruciate ligament reconstruction techniques partially restored the biomechanics of the knee in flexion, e.g. contact pressures were restored for pure flexion of the knee. The reconstruction techniques therefore partially restore the biomechanics of the knee in flexion. A double graft reconstruction is subjected to the highest tensile stresses.

Compressive Strength↗
PubMed2006

Dynamic in vitro measurement of posterior cruciate ligament load and tibiofemoral stress after TKA in dependence on tibiofemoral slope.

BACKGROUND: To prevent excessive tension on the posterior cruciate ligament, some knee prosthesis-systems offer the option of creating a posterior tibiofemoral slope of the tibial component. The objective of this study was to investigate the effect of the amount of tibiofemoral slope on the posterior cruciate ligament load and tibiofemoral contact stress after total knee arthroplasty under isokinetic in vitro conditions. METHODS: Twelve fresh frozen knee specimens were tested in a knee simulator. After implantation of the Interax I.S.A. knee prosthesis-system with a mobile bearing inlay, a bow shaped load transducer was fixed in the medial fibres of the posterior cruciate ligament. A pressure sensitive film was fixed on the femoral inlay surface. The test cycle simulated an isokinetic extension cycle from 120 degrees of flexion to full extension. First, posterior cruciate ligament load and tibiofemoral peak contact stress were measured with the tibial component implanted with a neutral tibial slope and then with 10 degrees posterior slope. FINDINGS: After implantation of the tibial component without tibial slope, posterior cruciate ligament load reached a maximum load of 29.5 N (SD 17.1 N) at 97.8 degrees knee flexion. Tibiofemoral contact stress on the medial compartment reached a maximum of 11.9 MPa (SD 2.4 MPa) on the medial compartment and 15.0 MPa (SD 6.1 MPa) on the lateral compartment. With a tibial slope of 10 degrees , posterior cruciate ligament load reached a maximum of 14.5N (SD 4.9N, P = 0.04) at 100.5 degrees knee flexion and tibiofemoral stress increased to a maximum of 13.3 MPa (SD 4.7 MPa, P = 0.38) medial and 17.4 MPa (SD 8.2 MPa, P = 0.22) lateral in knee extension. INTERPRETATION: Maximum posterior cruciate ligament load was observed at high knee flexion angles, decreasing to full extension. The implantation of the tibial base plate with 10 degrees dorsal slope reduced posterior cruciate ligament load significantly in knee flexion above 50 degrees and slightly increased tibiofemoral contact stress in knee extension. Therefore a posterior tibial slope prevents an excessive load on the posterior cruciate ligament while having little effect on tibiofemoral stress at high knee flexion angles.

Aged↗
PubMed2006

Tensile cervical facet capsule ligament mechanics: failure and subfailure responses in the rat.

Clinical, epidemiological, and biomechanical studies suggest the involvement of the cervical facet joint in neck pain. Mechanical studies have suggested the facet capsular ligament to be at risk for subfailure tensile injury during whiplash kinematics of the neck. Ligament mechanical properties can be altered by subfailure injury and such loading can induce cellular damage. However, at present, there is no clear understanding of the physiologic context of subfailure facet capsular ligament injury and mechanical implications for whiplash-related pain. Therefore, this study aimed to define a relationship between mechanical properties at failure and a subfailure condition associated with pain for tension in the rat cervical facet capsular ligament. Tensile failure studies of the C6/C7 rat cervical facet capsular ligament were performed using a customized vertebral distraction device. Force and displacement at failure were measured and stiffness and energy to failure were calculated. Vertebral motions and ligament deformations were tracked and maximum principal strains and their directions were calculated. Mean tensile force at failure (2.96 +/- 0.69 N) was significantly greater (p < 0.005) than force at subfailure (1.17 +/- 0.48 N). Mean ligament stiffness to failure was 0.75 +/- 0.27 N/mm. Maximum principal strain at failure (41.3 +/- 20.0%) was significantly higher (p = 0.003) than the corresponding subfailure value (23.1 +/- 9.3%). This study determined that failure and a subfailure painful condition were significantly different in ligament mechanics and findings provide preliminary insight into the relationship between mechanics and pain physiology for this ligament. Together with existing studies, these findings offer additional considerations for defining mechanical thresholds for painful injuries.

Animals↗