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Morphology of the mandibulo-stylohyoid ligament in human adults.

The mandibulo-stylohyoid ligament is a consistently occurring connective tissue band or sheet that courses between the angle of the mandible and the stylohyoid ligament. Previously, in a few instances it has been variously named and described as a thickening of deep cervical fascia. Recently, Shimada et al. (1986) described the connective tissue thickening and named it the mandibulo-stylohyoid ligament because of its arrangement and attachments. In the present study the ligament was dissected in 99 adult cadavers (both white and black, 98 right sides, 95 left sides). It was present in all of the specimens examined and has been classified into three types according to refinements in its morphology. Type 1: The ligament was a thick, separate band that coursed from the region of the angle of the mandible to the stylohyoid ligament. Type 2: The ligament had the same attachments as Type 1 but was more extensive, being continuous with the stylomandibular ligament. Type 3: The ligament had the same attachments as Type 1 but was thin and less well developed. The Type 1 arrangement occurred 41% of the time, Type 2, 37% of the time, and Type 3, 22% of the time. The consistency and arrangement of the ligament suggests an important role of additional structural support in the region of the angle of the mandible and hyoid bone.

Humans↗

Comparison of trigeminal receptor location and structure in the periodontal ligament of different types of teeth from the rat, cat, and monkey.

The periodontal ligament is richly innervated by mechanoreceptors whose cell bodies are located either in the trigeminal ganglion (TG) or the mesencephalic (MS) trigeminal nucleus. Both are sensitive to stretch of the ligament induced by tooth movement, but their thresholds, central connections, and functional significance differ. This study compared the location of TG and MS receptors in the periodontal ligament of cat teeth after labeling each by anterograde axonal transport. We also compared the location and ultrastructure of the feline TG receptors with labeled TG receptors in the periodontal ligament of monkey teeth and rat incisors in order to determine their location and ultrastructural properties. We found that the MS and TG receptors had a different distribution in the periodontal ligament of cat teeth; the MS terminals were concentrated below and next to the base of the roots, whereas the TG receptors were most numerous around the middle of the roots. The TG receptors of monkey teeth had a similar location to the feline TG receptors, but those of rat incisors were very different. Rat incisors are curved, continuously erupting teeth, and their TG receptors were located primarily on the lingual side in the alveolar (nonerupting) portion of the ligament. Ultrastructural comparisons found that most mechanoreceptors in the periodontal ligament of all the teeth had an unencapsulated branched Ruffini-like structure. The TG receptors in the rat incisor ligament were the largest; those of monkey had the most varied form. Some coiled or encapsulated receptors were found in the monkey and cat ligament, but not in the rat incisor ligament. The TG receptors appear to be located at sites that would be most easily stretched during tooth contact. The different sites and intensity of the stretch forces occurring during the use of different types of teeth may determine the variations in the size and location of the TG mechanoreceptors and of their associated support cells. The different distribution of MS receptors may contribute to their response thresholds and static properties, which differ from those of TG receptors.

Animals↗

Dexamethasone induces human spinal ligament derived cells toward osteogenic differentiation.

Ossification of spinal ligament is characterized by heterotopic bone formation in the spinal ligaments that are normally composed of fibrous tissues. The pathogenesis of ossification of spinal ligament has been suggested to be associated with osteogenic differentiation of the spinal ligament cells. In order to address this hypothesis, cells derived from human spinal ligament were investigated for their osteogenic potential by the treatment of dexamethasone in vitro. Yellow ligaments were obtained from patients with spinal disorders except ossification of spinal ligament during surgery, and the adhering tissues were removed completely. Most of the ligament cells treated with vehicle exhibited a fibroblast-like spindle shape, while the dexamethasone-treated cells acquired a polygonal morphology. Growth of the ligament cells was suppressed by dexamethasone at a high concentration. Some of the vehicle treated-cells were alkaline phosphatase-positive, and dexamethasone increased the alkaline phosphatase-positive cells and alkaline phosphatase activity in the cells. Northern blot analysis demonstrated that mRNAs expression of pro-alpha1(I) collagen and alkaline phosphatase were promoted by dexamethasone. Analysis by reverse transcription-polymerase chain reaction showed that expression of osteocalcin mRNA was detected in the dexamethasone-treated cells but not in the vehicle-treated cells, and dexamethasone-induced osteocalcin mRNA expression was promoted by 1,25-dihydroxyvitamin D(3). Finally, mineralization of extracellular matrix in the cells was induced by the presence of dexamethasone and 1,25-dihydroxyvitamin D(3). These results suggest for the first time that dexamethasone has a possible involvement in the osteoblastic differentiation of human spinal ligament cells.

Alkaline Phosphatase↗

Acute spinal ligament disruption: MR imaging with anatomic correlation.

Disruption of spinal ligaments can lead to instability that jeopardizes the spinal cord and nerve roots. Magnetic resonance (MR) imaging can directly image spinal ligaments; however, the sensitivity with which this modality demonstrates ligament injury has, to the authors' knowledge, not been reported. On a biomechanical testing machine, 28 cadaveric spines were subjected to controlled injury that resulted in ligament tears. The spines were then imaged with plain radiography, computed tomography, and MR imaging (1.5 T). The images were analyzed for evidence of ligament injury before dissection of the specimen. Forty-one of 52 (79%) ligament tears of various types were correctly identified at MR imaging. Disruptions of the anterior and posterior longitudinal ligaments were most conspicuous and were detected in all seven cases in which they were present (no false-positive or false-negative results); disruptions of the ligamentum flavum, capsular ligaments, and interspinous ligaments could also be identified but less reliably (three false-positive and 11 false-negative results). That MR imaging can reliably and directly allow assessment of spinal ligament disruption in this in vitro model suggests its potential utility for this assessment in patients.

Acute Disease↗

Viability of ligaments after freezing: an experimental study in a rabbit model.

Our purpose in this study was to assess ligament fibroblast viability after freezing by quantifying the subsequent ability of fibroblasts to synthesize collagen in vitro. Both medial collateral ligament (MCL) complexes from 40 adolescent rabbits were studied. Collagen production was determined by in vitro incubation of ligaments in 3H-proline (a collagen precursor) and subsequent analysis of 3H-hydroxyproline (a marker of newly synthesized collagen). Autoradiographs determined the distributions of ligament cell activity. All right MCL complexes served as fresh controls, providing a baseline of collagen production. Each left MCL was assigned to an experimental group and was either incubated fresh (10 animals); "killed" by drying, multiple freeze thawing, or cycloheximide (six animals); or slowly frozen at -70 degrees C without cryoprotection (24 animals). Collagen production of rapidly thawed ligaments was studied by proline incubation at 1 day, 9 days, or 6 weeks after freezing and was compared with that of contralateral fresh controls. Results demonstrate that some cells in the substance of these rabbit ligaments retained the ability to synthesize collagen in vitro after being frozen for up to 6 weeks. Mean collagen production of frozen ligaments was decreased, but tests of mean and median values as well as ratios were statistically similar to fresh contralateral ligaments in all animals. This postfreezing ligament cell survival and collagen production after -70 degrees C storage may have implications for ligament transplantation.

Animals↗

Human carpal ligament recruitment and three-dimensional carpal motion.

In five fresh human cadaver wrist joints six carpal ligaments and seven carpal bones were marked with small, radio-opaque pellets. Using a roentgenstereophotogrammetric measuring system, the ligamentous length changes and the kinematics of carpal bones were determined in different flexion and deviation positions of the hand. The data generated by this method differ significantly from lengthening data predicted by current concepts on carpal ligament functioning. The motions of carpal bones and the lengthening of the carpal ligaments were related to each other. It appeared that most carpal ligaments lengthen only during one half of a full movement cycle. Hence, ligaments seem to constrain either a dorsal- or a palmar-directed motion of the hand, or an ulnar- or a radial-directed motion of the hand. When the hand is in maximal radial deviation or maximal palmar flexion, none of the ligaments has a greater length than in the neutral situation. The tested parts of the lunatotriquetrum palmar ligament do not lengthen during any movement of the hand. Significant lengthening relative to the neutral situation was found for the radiocapitate palmar ligament (6.5% in maximal ulnar deviation and 11.7% in maximal dorsal flexion of the hand), and for the distal string of the radiolunate palmar ligament (6.4% in maximal ulnar deviation). It was confirmed that the carpals, apart from moving in the plane in which the hand motion takes place, also execute considerable out-of-plane motions during hand motions. The combination of these experimentally and simultaneously determined data on length change and on the movements of carpal bones are found to be necessary in order to give suitable explanations for the observed separate kinematical phenomena.

Carpal Bones↗

Strains and forces in selected carpal ligaments during in vitro flexion and deviation movements of the hand.

The forces induced in tiny wrist joint ligaments must be estimated in order to understand their role in the mechanism of the joint. We estimated forces in a number of selected ligaments in seven human wrist joint specimens, using a noninvasive method. The method is based on the rationale that the force generated in a ligament depends on its change of length with the joint under load. In vitro length changes of the ligaments were determined during flexion and deviation movements of the hand, using a roentgenstereophotogrammetric analysis technique. Subsequently, bone-ligament-bone (BLB) preparations were dissected from the specimens. From these BLB preparations the zero-force length and the force-elongation relationship were determined in a material testing machine. The forces generated in the ligaments during flexion and deviation were calculated by combining results on the in vitro ligament length changes, the zero-force length, and the force-elongation relationship. Large interspecimen variations of the force patterns were found. Due to this variability, it is not possible to obtain quantitative models for the kinetic behavior of the ligaments. However, qualitative trends could be distilled from the strain and force patterns. It is clear that for most ligaments, the zero-force lengths were not equal to the lengths they possessed in the neutral position of the hand. Furthermore, it could be shown which motions of the hand would most likely strain a particular ligament. It could be shown that the variations in the force patterns originate mainly from variations in the zero-force lengths, and from variations in the force-strain relationship between specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Using a freeze substitution fixation technique and histological crimp analysis for characterizing regions of strain in ligaments loaded in situ.

Type I collagen fibrils in tendons and ligaments assume a sinusoidal wave shape, or crimp, which straightens only with tensile load. The load response of crimp has been studied primarily in isolated subunits and not in complex, intact structures. The purpose of our study was to determine if freeze substitution fixation of an entire ligament could preserve changes in crimp morphology induced by functionally relevant loading conditions. We hypothesized that, in ligaments prepared by freeze-substitution fixation under load, crimp would progressively extinguish with increasing loads, and nonuniform strain following partial section could be detected from crimp morphology. Tensile loads ranging from 0 to 220 N were applied to patellar ligaments of 16 fresh rabbit stifle joints using simulated isometric quadriceps pull through the patella. The loaded joints were flash frozen with isopentane cooled in liquid nitrogen, then fixed using freeze substitution. Another six ligaments were loaded to 150 N following incision of the anterior third and evaluated under polarized light microscopy for crimp distribution. Ligaments with no or low loads could be identified by the presence of crimp on mid-sagittal sections. Strain distribution was inhomogeneous, in that the ligament displayed a consistent pattern of collagen fiber recruitment among three morphologically distinct bands seen on coronal sections. At very low loads (about 18 N), the fibers in a central band were uncrimped; anterior and deep bands uncrimped at higher loads. The crimp in the entire specimen was extinguished at about 67 N, which correlates closely with the previously reported toe-region of the stress-strain curve of the rabbit patellar ligament. When the anterior third was transected, fibers within that segment retained a crimp in ligaments prepared under loads that ordinarily would ablate all crimp. These findings suggest that freeze fixation could be used to map the functional microstructure of ligaments or tendons.

Animals↗

Collagen and proteoglycan in a sea urchin ligament with mutable mechanical properties.

The "problematic ligament" of sea urchins is a connective tissue which crosses the ball-and-socket joint between spine and body wall. The problem of this ligament is that it is composed of parallel collagen fibrils, yet normally undergoes rapid and dramatic alterations in mechanical properties and in length. Previous work has suggested that the collagen fibrils of the ligament are able to slide past one another during length changes but are inhibited from sliding when the ligament is in "catch". In this model of the ligament both the collagen fibrils and the interfibrillar matrix are mechanically important. We have found that the collagen fibrils of the spine ligament of the pencil urchin Eucidaris tribuloides are discontinuous and end by tapering within the body of the ligament. Intact fibrils that have been isolated from the ligament vary by more than an order of magnitude in length and in radius but have a constant length/radius (aspect) ratio of about 5,300. This is the first determination of the aspect ratio of collagen fibrils from any source. The constant aspect ratio of the fibrils is consistent with their functioning as the discontinuous fiber phase in a fiber-reinforced composite material, while the high value of the aspect ratio indicates that the nonfibrillar matrix, which must act to transfer stress between fibrils, can produce a stiff and strong ligament even if it is several orders of magnitude weaker and more compliant than the fibrils. Moreover, the tensile properties of the ligament may be determined by the properties of the matrix. A prominent component of the interfibrillar matrix is a proteoglycan which associates with specific bands at the surface of the collagen fibrils through noncovalent binding of its core protein. The glycosaminoglycan moiety of this proteoglycan is partly comprised of chondroitin sulfate/dermatan sulfate polymers. These results are consistent with the "sliding fibril" hypothesis and suggest that the proteoglycan may be an important component of the stress-transfer matrix.

Animals↗

Ligaments of the larynx and the adjacent pharynx and esophagus.

Two ligament systems of the larynx are demonstrated by dissection. The suspensory ligament of the esophagus is attached to the posterior aspect of the cricoid cartilage and is also a part of the fascial sheath which is common to the hyoid, thyroid, and cricoid. The ligaments at the inner margins of the vocal, ventricular, and aryepiglottic folds are distinctive in site and, inferentially, in function. The aryepiglottic ligaments join at the incisura between the arytenoid cartilages and are continued as the corniculopharyngeal ligament which splays into the flexible tissues in the anterior wall of the hypopharynx, posterior to the suspensory ligament of the esophagus. These ligament systems are involved in two different actions in swallow. The gross superior and anterior motions of the larynx are transmitted to the esophagus by the suspensory ligament, so that the esophagus is elevated in relation to the bolus and is also opened. These esophageal displacements resemble, in effect, the swallow displacements of the pharyngoesophageal segment and of the constrictor wall of the hypopharynx. The marginal ligaments of the laryngeal folds help to implement the constriction and closure of the larynx during swallow. By anatomical inference, the corniculopharyngeal ligament effects vertical traction within the flexible tissues of the anterior wall of the hypopharynx.

Adult↗

Comparative evaluation of different anchoring techniques for synthetic cruciate ligaments. A biomechanical and animal investigation.

Under certain well-defined indications alloplastic material may be used in cruciate ligament surgery. The stability and survival of such a synthetic ligament is to a great extent dependent on the anchorage with which it is fastened to the bone. Most fixation methods have proved to be too weak or have revealed other essential drawbacks, resulting in clinical and experimental failure. A new ligament fixation device (LFD) was developed and tested biomechanically and in animal experiments. In the biomechanic investigation the new LFD was compared to single staples, double staples in the belt-buckle technique, and ligament guidance through additional bone tunnels (Z-technique). The tests were carried out on human cadaver knees, plastic bones, and dog stifle joints. The evaluated parameters were linear and maximum load, stiffness, and elongation. In addition, hysteresis tests were performed to assay the long-term resistance of the fixation. The tests showed a significant superiority of the LFD in all measured variables compared to the other anchorages. The pull-out strength, at 1866 +/- 43 N (cadaver knee), was about four times that for the single staple, and about twice as high as that for the double staple and Z-technique. The animal experiments were performed on German shepherd cross-breed dogs. In six animals the anterior cruciate ligaments were excised bilaterally and replaced by a 6-mm Trevira ligament, on one side anchored with staples in the Z-technique, on the other with the LFD. Postoperatively the dogs were allowed to move freely; no additional protection was employed. After 6 months the animals were sacrificed and the knees examined macroscopically, radiologically, microscopically, and by biomechanical testing. After half a year of implantation, the pull-out strength of the alloplastic ligament was 662 +/- 62 N for the LFD and 531 +/- 67 N for the staples. Three ligaments in the staple group and one in the LFD group had ruptured completely, and two ligaments partially, one in each group. The average anterior drawer in the LFD group was 2.8 mm, in the staple group 4.0 mm. In all cases the alloplastic ligament was separated from the bone by a fibrous interface. None of the fixation devices showed signs of loosening. There was no foreign body reaction around the anchorages. Major cartilage degeneration was observed in two stifle joints of each group, mainly associated with instability.

Animals↗

[Microangiographic evaluation of vascular supply of the medial collateral ligament of the knee joint].

Because the vascularization of ligaments is an important factor in ligament healing we wanted to examine the vascularization status of the medial collateral ligament of the knee. The type of vascularization was examined by microangiographie of 21 postmortem preparations. We could observe a vascularization from the proximal end of the ligament by one or two major vessels in all cases. These vessels were mostly localized in the ventral third of the ligament. From the proximal to the distal part of the ligament we found a decreasing density of blood vessels. We could not observe vessel free ligament areas. Due to this vascularization status we would advise the differentiation of two ligament areas respecting the following therapy. Because of the good vascularization in the proximal part of the ligament we can accept good conditions concerning complete healing after a non-operative treatment and an operative therapy by suture or refixation. In the case of interligamentous and distal ruptures operative reconstruction by sutures often in difficult and a conservative therapy leads to a high rate of poor results. Therefore we advise fibrin bonding in these ligament areas if a surgical procedure is indicated because of the high risk of vessel strangulation after suture.

Angiography↗

Pitfalls of magnetic resonance imaging of alar ligament.

An observational study of variations in the appearance of the alar ligament on magnetic resonance imaging (MRI) and the normal range of lateral flexion and rotation of the atlas was performed to validate some of the premises underlying the use of MRI for the detection of injuries to the alar ligament. Fifteen healthy volunteers were included. Three sets of coronal proton-density images, and axial T2-weighted images of the craniovertebral junction, were obtained at 0.5 T with the neck in neutral position and laterally flexed (coronal proton density) or rotated (axial T2). Five of the subjects also underwent imaging at 1.5 T. The scans were independently examined twice by two radiologists. The presence of alar ligaments was recorded and a three-point scale used to grade the extent of hyperintensity exhibited by the structures: the ligament were graded as 2 and 3 if, respectively, less or more of its cross-section was hyperintense, whereas grade 1 represented a hypointense ligament. The effect of lateral flexion on image quality was assessed. Concordance analysis of the data were performed before and after dichotomising the data on grading. The atlanto-axial angle and rotation of the atlas were measured. The magnitude of movement to right was normalised to that to the left to give, respectively, the flexion index and the rotation index. The alar ligaments were most reliably seen on coronal proton-density scans, with a Maxwell's RE of 0.96 as compared with 0.46 for sagittal images. Flexion of the neck improved definition of the ligaments in only rare instances. Inter-observer disagreement was marked with respect to grading of the ligament on both coronal [composite proportion of agreement (p0)=0.44; 95% confidence intervals: 0.26, 0.64)] and sagittal scans [p0=0.40 (0.19, 0.63)]. Dichotomising the data did not appreciably improve reliability [Maxwell's RE: -0.11 (coronal scans), -0.20 (sagittal scans)]: for ligaments which demonstrated hypertensive areas (grades 2 and 3) there was complete lack of agreement for both coronal [p2=0 (0, 0.25)] and sagittal scans [p2=0 (0-0.30)]. A large response bias was found in the reports of both readers albeit in opposite directions. There was poor concordance between scans obtained at different field strengths [RE (coronal images)=0.25; RE (sagittal images)=0.14). Mean flexion index and mean rotation index were 1.00 (SD 0.03) and 1.01 (SD 0.06), respectively. The MR imaging may not be the investigation of choice for the investigation of subtle injuries to the alar ligament. Whether it can be substituted by kinematic assessment of the occipito-atlanto-axial complex with MRI warrants investigation.

Adult↗

Sonography of injury of the ulnar collateral ligament of the elbow-initial experience.

OBJECTIVE: The purpose of this study is to describe the sonographic appearance of injuries of the ulnar collateral ligament (UCL) of the elbow. DESIGN AND PATIENTS: Eight non-professional male baseball pitchers, ages 13-35 years, with medial elbow pain and clinical suspicion of ulnar collateral ligament injury, were referred for imaging. All eight underwent sonography of the affected and contralateral asymptomatic elbow, and six also underwent MR imaging. Neither valgus stress nor power Doppler was used during the sonographic examinations. Time from onset of symptoms to imaging was 1.5 weeks to 6 months. Three patients had surgical confirmation of their injuries, with time from imaging to surgery of 2 days to 9 months. RESULTS: In four patients, the UCL was ruptured, manifest sonographically in three cases as discontinuity of the normally hyperechoic ligament with anechoic fluid in the gap and in one case as non-visualization of the ligament with heterogeneous echogenicity in the expected location of the ligament. Two adolescent patients had avulsions of the UCL from the medial epicondyle, with sonographic demonstration of the avulsed echogenic bony fragment in both cases. One patient had a mild sprain, manifest as mild thickening and decreased echogenicity of the ligament sonographically compared with the contralateral normal elbow, with mild surrounding hypoechoic edema. The eighth patient had a small partial tear of the deep surface of the distal aspect of the ligament, visualized as a hypoechoic focus between the deep surface of the ligament and its ulnar attachment. CONCLUSION: Tears of the ulnar collateral ligament are manifested sonographically as non-visualization of the ligament or alteration of the normal morphology.

Adolescent↗

Arcuate ligament of the wrist: normal MR appearance and its relationship to palmar midcarpal instability: a cadaveric study.

OBJECTIVE: To describe the magnetic resonance (MR) imaging and gross anatomic appearance of the scaphocapitate (SC) ligament and triquetrohamocapitate (THC) ligament, which are the radial and ulnar limbs of the composite arcuate ligament, a critical volar midcarpal stabilizing ligament. DESIGN: T1 spin-echo and 3D gradient-echo MR imaging in the standard, coronal oblique, and axial oblique planes were performed both before and following midcarpal arthrography in seven cadaveric wrists. The seven specimens were then sectioned in selected planes to optimally visualize the SC and THC ligaments. These specimens were analyzed and correlated with their corresponding MR images. RESULTS: The SC and THC ligaments can be visualized in MR images as structures of low signal intensity that form an inverted "V" joining the proximal and distal carpal rows. The entire ligamentous complex is best visualized with coronal and axial oblique MR imaging but can also be seen in standard imaging planes. CONCLUSION: SC and THC ligaments together form the arcuate ligament of the wrist. Their function is crucial to the normal functioning of the wrist. Palmar midcarpal instability (PMCI) is a resulting condition when abnormalities of these ligaments occur. Dedicated MR imaging in the coronal and axial imaging planes can be performed in patients suspected of having PCMI.

Aged↗

MR imaging findings in spring ligament insufficiency.

OBJECTIVE: Spring ligament insufficiency is associated with chronic posterior tibial tendon dysfunction, and may constitute an indication for surgical repair or reconstruction. This study examines the accuracy of MRI for the diagnosis of insufficiency of the spring ligament. DESIGN AND PATIENTS: Two experienced musculoskeletal radiologists independently scored the MRI findings in 13 cases of surgically proven spring ligament insufficiency and in 18 control subjects, using a standardized scoring system. RESULTS: Insufficiency of the spring ligament was associated with increased signal heterogeneity on short TE spin echo images, and an increase in the thickness of the medial portion of the ligament. The sensitivity of MRI for the diagnosis of spring ligament insufficiency was 54-77%, while the specificity was 100%. MRI assessment of the plantar portion of the spring ligament was unreliable (kappa=0.33), but the assessment of global ligament integrity was substantially reproducible (kappa=0.76). CONCLUSION: The medial portion of the spring ligament can be reliably assessed on routine MRI. The findings of spring ligament insufficiency on MRI are only moderately sensitive but highly specific.

Case-Control Studies↗

An MRI study of the meniscofemoral and transverse ligaments of the knee.

Our aim was to assess the anatomic localization, dimensions and incidence of the transverse and meniscofemoral ligaments, which can show anatomic variations or be mistaken for some pathologic conditions. In 100 healthy subjects (52 female, 48 male) whose ages ranged from 12 to 84 years, sagittal and coronal magnetic resonance images of the knee were obtained. There was at least one anterior or posterior meniscofemoral ligament in 82 cases. The anterior meniscofemoral ligament was present in 8 of the female and 4 of the male subjects. The posterior meniscofemoral ligament was found in 20 female and 22 male subjects. Both the anterior and posterior meniscofemoral ligaments were present in 15 female and 13 male subjects. The transverse ligament of knee was encountered in 19 female and 12 male subjects. In the females, average lengths of the anterior and posterior meniscofemoral ligaments were 9.87 +/- 4.79 mm and 25.60 +/- 5.50 mm, respectively. The corresponding values in the males were 11.11 +/- 2.57 mm and 28.80 +/- 5.49 mm, respectively. In the females, average width of the anterior and posterior meniscofemoral ligaments were 2.45 +/- 1.02 mm and 2.30 +/- 1.15 mm, respectively. The corresponding values in the males were 2.52 +/- 0.87 mm and 2.30 +/- 1.15 mm, respectively. On MRI assessment, in order to differentiate intra-articular lesions such as osteochondral and meniscal fragments or pseudotear of the lateral meniscus from the normal ligamentous anatomy of knee, the orientation and characteristic localization of the meniscofemoral ligaments should be taken into account. The French version of this article is available in the form of electronic supplementary material and can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00276-002-0023-8.

Adolescent↗

Scapholunate ligament reconstruction using a periosteal flap of the iliac crest: a biomechanical study.

INTRODUCTION: Advances continue to improve direct reconstruction of the dorsal scapholunate (SL) ligament, which is the strongest part of the entire SL ligament and is known as the turning point between the scaphoid and lunate. This study was designed to compare the biomechanical properties of the dorsal SL ligament with those of a periosteal flap of the iliac crest, which is a new graft candidate for dorsal SL reconstruction. MATERIALS AND METHODS: A bone-ligament-bone complex was harvested for biomechanical testing from the iliac crest and the dorsal SL complex. Ten specimens could be prepared in each group. After potting the bone blocks in methylmethacrylate for stable fixation, the specimens were tested, using a servohydraulic testing system, at a rate of 10 mm/min. RESULTS: Failure displacement, failure force, failure stress, energy to failure, and stiffness were assessed for both groups. Eight specimens in each group were tested successfully. In the ligament group, six specimens failed at the ligament level, whereas two failed at the insertion of the scaphoid. In the periosteum group, all eight specimens failed at the ligament level. The failure force of the dorsal SL ligament averaged 171.8 N, failure stress was 10.3 N/mm2, and failure displacement amounted to 2.9 mm. Energy to failure was 269.1 N-mm, and stiffness averaged 77.2 N/mm. Failure force of the periosteal flap amounted to 144.3 N, failure stress was 9.9 N/mm2, failure displacement was 3.0 mm, and energy to failure was 217.9 N-mm. Stiffness of the periosteal flap measured 60.5 N/mm. Comparison of the dorsal SL ligament and the periosteal flap of the iliac crest revealed no significant biomechanical differences. CONCLUSION: Therefore, the biomechanical properties of the periosteal flap recommend its use for reconstruction of the dorsal SL ligament.

Biomechanical Phenomena↗