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PubMed2000

Equivalence of single and incremental subfailure stretches of rabbit anterior cruciate ligament.

Experimental models are often used in the laboratory to produce incomplete soft-tissue injuries simulating those observed clinically. Single and incremental stretch protocols have been utilized. The latter has many advantages over the former. This study was designed to determine if incremental and single ligamentous stretches are biomechanically equivalent. Eleven paired fresh rabbit bone-anterior cruciate ligament-bone preparations were used. One of each pair (single-stretch protocol) was stretched to 88% of the average failure deformation and then stretched to failure. The other ligament (incremental-stretch protocol) was stretched to 55, 66, 77, and 88% of the average failure deformation and then stretched to failure. All stretches were performed at 1.2 m/sec. Stress-relaxation tests were performed before and after the 88% stretch for both stretch protocols. Relaxation curves were parameterized as forces at six time points and were also fitted to a three-element model. Load-deformation curves recorded during stretch to failure were characterized by eight parameters. Each incremental stretch step produced a significant increase in deformation, indicating alteration in the mechanical properties of the ligament. Both groups of ligaments, when intact, exhibited no differences in relaxation curves (p > 0.2). The 88% stretches, produced by each of the two stretch protocols, significantly altered the viscoelastic behavior of the ligaments (p < 0.002). However, after the 88% stretch, there were no differences in either viscoelastic (p > 0.1) or load-deformation (p > 0.1) parameters of the two stretch protocols. In conclusion, the 88% subfailure stretch significantly altered the mechanical properties of ligament, and the incremental and single stretches were biomechanically equivalent.

Animals↗
PubMed1993

Bone-ligament interaction in patellar tendon reconstruction of the ACL.

The bone-ligament junction is one of the most complex biological tissues. Its key function is distribution of mechanical loads applied to the ligament in such a way as to diminish the concentration of stresses or shearing at the interface. This paper reports an experimental assessment of the extent to which a nearly normal junction is formed following reconstruction of the anterior cruciate ligament (ACL) with patellar tendon in 20 New Zealand white rabbits sacrificed after 2-38 weeks. A histological comparison was also made with cadaver ACLs. After 5 weeks the new ligament was still separate from the tunnel wall, inflammation was no longer present, and there was no junction tissue. A thin fibrocartilage layer was observed between the bone and the ligament after 12 weeks and was thicker 6 weeks later. After 28 weeks, there was a substantial layer of fibrocartilage. The new junction was virtually "physiological" by the 38th week, with all four layers present. Many fibrocartilaginous cells were also visible between the collagen fibres. The bone-ligament insertion was almost normal. These findings indicate that tendon reconstruction results in the formation of a structure very similar to a physiological junction, and thus ensures better load distribution over a greater ligament insertion area.

Animals↗
PubMed1988

Ligaments of the lumbar spine: a review.

A thorough knowledge of the anatomy of the intervertebral ligaments is necessary to provide the basis for good clinical management of back injuries. This paper reviews the literature concerning the lumbar ligaments, including the zygoapophyseal joints. While general principles regarding the anatomy of the ligaments is relatively clear, areas of omission or discrepancy exist. There is very little substantiated information on: the dimensional characteristics of the ligaments; the fibre lengths of the facet capsule; the attachments of the anterior longitudinal ligament; the orientation of the interspinous ligament, and the extent of the supraspinous ligament.

Humans↗
PubMed1992

[Fascicular and sub-fascicular architecture of the cruciate ligament].

The details of the collagen fascicle morphology and the vascularization of the anterior and the posterior cruciate ligament were examined by the combined use of histology, transmission- and scanning electron microscopy, morphometry and immunohistochemistry. The diameters of the collagenous fibrils in the anterior cruciate ligament ranged between 20 and 155 nm (x = 74 nm, s = 18.8 nm) and in the posterior cruciate ligament between 20 and 175 nm (x = 82 nm, s = 25.4 nm). Type III and VI collagen were found distributed throughout the matrix but concentrated in the attachment regions of the ligaments. The content of type IV collagen in the anterior cruciate ligament was low. The amount of arterioles revealed a typical pattern (anterior cruciate ligament: less than 30 years = 2.94/mm2, greater than 90 years = 2.02/mm2, proximal = 3.15/mm2, distal = 2.18/mm2; posterior cruciate ligament: less than 30 years = 4.69/mm2, greater than 90 years = 3.87/mm2, proximal = 4.08/mm2, distal = 3.98/mm2).

Adult↗
PubMed1997

[MRI diagnosis of lesions of the anterior cruciate ligament--comparison of 1.0 Tesla and 0.2 Tesla. Initial results].

The purpose of our study was to compare the diagnostic performance of a 0.2-T MRI unit and a 1.0-T MRI unit in the evaluation of the anterior cruciate ligament in patients with clinically suspected lesions of this ligament. Twenty four patients with clinically suspected lesions of the anterior cruciate ligament underwent MRI of the knee on both 0.2-T and 1.0-T MRI units. Three independent observers evaluated the examinations for primary and secondary signs of a tear of the anterior cruciate ligament. Frequency of these signs was determined for both modalities, and observer agreement was assessed using the kappa statistic. Sixteen of 24 patients had signs of tears of the anterior cruciate ligament on the 1.0-T unit; the 0.2-T unit detected primary signs in 15/16 (93%) patients and secondary signs in 7/12 (43%) patients. In 8 patients the 1.0 T unit showed neither primary nor secondary signs for tears of the anterior cruciate ligament; in these patients the 0.2-T unit detected primary signs in 1/8 cases (12%), and secondary signs in 3/8 cases (37%). Observer agreement was very good for the 1.0-T unit and fair for the 0.2-T unit. There is no substantial difference between 1.0-T units and 0.2-T MRI units in the visualisation of primary signs of tears of the anterior cruciate ligament. In the visualisation of secondary signs, 1.0-T units are superior to 0.2-T units, and there is a surprisingly high rate of false-positive results with the 0.2-T unit. As to the reproducibility of the results, the 1.0-T unit is far superior to the 0.2-T unit.

Adult↗
PubMed1998

Complex alterations in gene expression occur in the knee ligaments of the skeletally mature multiparous rabbit during pregnancy.

Pregnancy is known to influence the function of ligaments of the knee in both humans and rabbits. During pregnancy, ligament laxity increases. The mechanism by which these changes in ligament function occur is unknown. The present study was undertaken to assess changes in the pattern of gene expression for a number of molecules which could be involved in the alterations in tissue function. Using RNA isolated from pregnant and age-matched nonpregnant rabbits, levels of mRNA for matrix molecules, proteinases and inhibitors, cytokines and growth factors and inducible nitric oxide synthase were assessed by semi-quantitative RT-PCR. The results indicate that the pregnancy-induced changes in the pattern of gene expression is very complex and differences in the changes observed for the medial collateral ligament and the anterior cruciate ligament may also indicate that ligament-specific effects of pregnancy occur. mRNA levels of some molecules were significantly elevated or suppressed, while others were unchanged, indicating that the changes observed were specific rather than general. While the extent of the molecules assessed was designed to be representative rather than exhaustive, the results indicate that there is likely no simple cause and effect relationship between the observed mechanical alterations during pregnancy and alterations in gene expression in the affected ligaments.

Animals↗
PubMed2002

Loading response following anterior cruciate ligament reconstruction during the parallel squat exercise.

OBJECTIVE: To determine if individuals 1.5-15 months post-anterior cruciate ligament reconstruction demonstrated an equal loading response on their involved and uninvolved lower extremity during a parallel squat exercise versus a control group. DESIGN: Four-group repeated measures design with one between-subject factor (time post-anterior cruciate ligament reconstruction) and two within-subject factors (knee angle and added weight). BACKGROUND: It has been a clinical observation that post-anterior cruciate ligament reconstruction, individuals do not place equal amounts of weight upon each lower extremity during double-leg exercises. METHODS: Twenty-four subjects were in each of the experimental groups, 1.5-4 months, 6-7 months, and 12-15 months post-anterior cruciate ligament reconstruction, while 24 subjects without history of lower extremity pathology/injury served as the control group. Pedar in-shoe sensors were placed inside the subjects' shoes to record loading response patterns during the exercises. All performed 3 sets of 9 randomized squats to each of the three knee flexion angles (30 degrees, 60 degrees, and 90 degrees ) with the three different weights (20.45 kg bar only, 35%, and 50% body mass) using a Smith squat rack. A three-way repeated measures ANOVA (P < 0.050) was used to compare the differences between groups in loading response statically between the uninvolved and involved lower extremity for each of the different weights at each knee flexion angle during the squat exercise. RESULTS: The three-way repeated measures ANOVA revealed that there was a significant group effect (P < 0.001). Thus, the amount of time post-anterior cruciate ligament reconstruction affected the difference in the subjects' loading response for the uninvolved and involved lower extremities. There was also a three-way interaction, indicating that the difference in loading response was dependent on the group, amount of knee flexion, and amount of added weight (P = 0.010). CONCLUSION: These data suggest that subjects significantly load their uninvolved lower extremity until 12-15 months post-anterior cruciate ligament reconstruction. RELEVANCE: Based on the results of this study, caution may be warranted when adding resistance during the parallel squat for an individual's first year post-anterior cruciate ligament reconstruction, particularly with less knee flexion to avoid compensation and injury.

Adult↗
PubMed1997

Anatomy of the intermetacarpal ligaments of the carpometacarpal joints of the fingers.

In this study, the structure of the retaining ligaments between the proximal metacarpal bones of the fingers was defined. Anatomic dissections were performed on 10 fresh cadavers. Four separate ligaments were found: a dorsal metacarpal ligament, a palmar metacarpal ligament, and 2 interosseous ligaments oriented in a V-shaped configuration. The V-shaped interosseous ligaments were found to be the strongest; along with the palmar and dorsal intermetacarpal ligaments, they form a very strong connection between the bases of the adjacent metacarpals.

Carpal Bones↗
PubMed1997

Cruciate ligament graft intra-articular distances.

Although the length of the anterior and posterior cruciate ligaments have been well characterized in the literature, we are not aware of any studies of the actual length of grafts used in reconstruction of these ligaments. We dissected and measured these distances for 18 cadaver knees of varying size and sex. The precise location of ideal guide pin placement was located based on current recommendations, and the intra-articular graft length was measured with a micrometer by two separate observers. We found that the average intra-articular graft length for the anterior cruciate ligament is 23.56 mm (SD, 0.98 mm), the posterior cruciate ligament is 30.72 mm (SD, 2.61 mm) and the patella tendon graft intertendinous distance is 43.33 mm (SD, 4.21 mm) We conclude that the intra-articular distance for cruciate ligament grafts is less than published values for the ligaments themselves, and that the patella tendon graft is of adequate length to be used for reconstruction of these ligaments.

Anterior Cruciate Ligament↗
PubMed2002

Anterior cruciate ligament injuries in young females playing soccer at senior levels.

The aim of this investigation was to study the consequences of anterior cruciate ligament injuries in female soccer players. Special interest was focused on young female soccer players (< 16 years) sustaining anterior cruciate ligament injuries when playing at a senior level, which means playing together with players 19 years or older. In Sweden, all players belonging to an organized soccer club are insured by the same insurance company, the Folksam Insurance Company. Data of all soccer-related knee injuries in females reported to the Folksam Insurance Company between 1994 and 1998 were collected. A questionnaire was sent to 978 females who were registered to have sustained a knee injury before the age of 20 years. The response rate was 79%. Three hundred and ninety-eight female soccer players who had sustained an anterior cruciate ligament injury before the age of 19 years were analysed. Most of their anterior cruciate ligament injuries had been diagnosed using arthroscopy or magnetic resonance imaging (84%). Thirty-eight percent of the players had been injured before the age of 16 years. Of these, 39% were injured when playing in senior teams. When playing in senior teams 59% of the players below the age of 16 years and 44% of the players 16 years or older sustained their ACL injuries during contact situations. At the time of this investigation (2-7 years after the anterior cruciate ligament injury), altogether 78% (n = 311) reported that they had stopped playing soccer. The most common reason (80%) was symptoms from their anterior cruciate ligament-injured knee. It appears that many young female soccer players injure their anterior cruciate ligament when playing at a senior level. Therefore, we suggest that female soccer players under the age of 16 years should be allowed to participate only in practice sessions but not games at a senior level.

Adolescent↗
PubMed2004

The effect of alpha-2 macroglobulin on the healing of ruptured anterior cruciate ligament in rabbits.

To investigate the effect of modification of biological environmental conditions, one of the factors influencing the healing of anterior cruciate ligament rupture, we performed experimental anterior cruciate ligament ruptures on New Zealand rabbits. After experimental rupture, intra-articular alpha-2 macroglobulin was injected into the knees of the rabbits in the experiment group to prevent structural changes resulting from the enzymatic reactions in the ruptured anterior cruciate ligament. At the end of 10th day of the experiment, we observed that the anterior cruciate ligaments in the experiment group had retained their prerupture brightness and volume when compared with the control group in which intraarticular alpha-2 macroglobulin had not been injected. We also noted that the anterior cruciate ligaments in the experiment group had not retracted or swollen, the incision sites were regular and clean, and they did not show any signs of degeneration. In the histological examination, the anterior cruciate ligaments in the control groups showed disruption of the collagen network and a significant diminution in number of fibroblasts and fibrocytes (p <.001). At the end of this study, we concluded that the necessary conditions for the healing and repair of ruptured anterior cruciate ligament could exist if the enzymatic and biological environments were under control.

Animals↗
PubMed1999

Direct-, fibroblast- and myoblast-mediated gene transfer to the anterior cruciate ligament.

The anterior cruciate ligament (ACL) has poor capabilities of healing. Maturation or "ligamentization" of the ACL following autograft or allograft reconstruction has been found slow and remains under investigation. In vitro and in vivo studies have shown that platelet-derived growth factor (PDGF), transforming growth factor-beta (TGF-beta), and epidermal growth factor (EGF) have the potential to improve ligament healing. Gene therapy approaches may represent a new alternative in delivering these specific growth factors to the ACL. The aim of this study was to investigate the feasibility of three different gene therapy approaches (direct-, fibroblast-, and myoblast-mediated gene transfer) to the ACL. Rabbit myoblasts and ACL-fibroblasts were transduced with 5 x 10(7) recombinant adenoviral particles carrying the LacZ reporter gene (MOI = 50). Myoblasts and fibroblasts (1 x 10(6)) were each injected into the right ACL of 10 adult rabbits; direct injection of 5 x 10(7) adenoviral particles was performed in 10 other rabbits. The left side was used as sham. The beta-galactosidase production was revealed using the LacZ histochemical technique. The transduced fibroblasts and myoblasts were found in the ligament tissue and in the synovial tissue surrounding the ACL at 4, 7, 14, and 21 days postinjection. The myoblasts fused and formed myotubes in the ligament. The direct approach also allowed the transfer of the marker gene in the ligament at 4, 7, 21, and 42 days postinjection. X-gal staining revealed no expression of beta-galactosidase in the sham ligament. The presence of cells expressing the marker gene in the ACL opens up the possibility of delivering proteins (i.e., PDGF, TGF-beta, and EGF) capable of improving ACL healing and graft maturation. Furthermore, engineered myoblasts may mediate and accelerate the intraligament neovascularization. This new technology based on gene therapy and tissue engineering may allow a persistent expression of selected growth factors to enhance ACL healing following injury.

Adenoviridae↗
PubMed2001

Magnetic resonance imaging of reconstructed anterior cruciate ligament.

After anterior cruciate ligament reconstruction with autologous patellar tendon, 23 patients who had clinically stable knees were studied prospectively with sequential magnetic resonance imaging 1, 2, 3, 6, and 12 months after surgery. The images of the anterior cruciate ligament were obtained with a 1.5 tesla magnetic resonance scanner in the oblique sagittal, coronal, and oblique axial planes. The cross-sectional area and signal intensity on the reconstructed anterior cruciate ligament were measured in an oblique axial image. The usefulness of the oblique axial image in evaluating the integrity of the reconstructed anterior cruciate ligament was seen. The result showed that the diameter of the graft increased by 70% of its initial size and the signal intensity of the reconstructed graft also showed a tendency to increase. In three patients, there was discontinuity in the graft direction on the oblique sagittal image, but on the oblique axial image there was no evidence of reconstructed anterior cruciate ligament rupture in the sequential images. This shows the value of the oblique axial image in evaluating the integrity of the reconstructed anterior cruciate ligament. Also, sufficient notchplasty in anterior cruciate ligament reconstruction may be needed to prevent graft impingement.

Adolescent↗
PubMed2003

Monopolar thermal treatment of symptomatic anterior cruciate ligament instability.

Patients with anterior cruciate ligament instability resulting from incomplete tears or elongation in continuity without ligament detachment historically have been treated conservatively or by graft replacement. The literature is sparse regarding alternative treatments. The current study presents experience using monopolar thermal repair on 28 consecutive knees with partial anterior cruciate ligament tears all symptomatically unstable. All lesions were less than 6 months old (average, 77 days; range, 7-180 days) and with a difference of 6 mm or more (average, 9 mm; range, 6-13 mm) when comparing both knees using KT-1000 evaluation. Incomplete tears of the anterior cruciate ligament were seen at arthroscopic evaluation. The rehabilitation protocol included use of a brace for at least 6 weeks and progressive weightbearing. A 2-year minimum followup (range, 24-35 months) was done in all patients following the International Knee Documentation Committee guidelines. The overall outcome was normal or nearly normal in 96% of the patients. One failure occurred at 8 weeks. Twenty-six knees had a KT-1000 difference between 0 and 2 mm (average, 1.9 mm). Because thermal application causes death to some of the cells directly treated, it should be taken into account in selection and application. Immediately after thermal use, the anterior cruciate ligament, although thicker and tighter, is at first weaker than normal. Rehabilitation and compliance are critical during early ligament healing. This procedure seems to be a reasonable alternative to anterior cruciate ligament grafting in selected patients.

Adult↗
PubMed2004

Development of a finite element model of the upper cervical spine and a parameter study of ligament characteristics.

STUDY DESIGN: Numeric techniques were used to study the upper cervical spine. OBJECTIVES: To develop and validate an anatomic detailed finite element model of the ligamentous upper cervical spine and to analyze the effect of material properties of the ligaments on spinal kinematics. SUMMARY OF BACKGROUND DATA: Cervical spinal injuries may be prevented with an increased knowledge of spinal behavior and injury mechanisms. The finite element method is tempting to use because stresses and strains in the different tissues can be studied during the course of loading. The authors know of no published results so far of validated finite element models that implement the complex geometry of the upper cervical spine. METHODS: The finite element model was developed with anatomic detail from computed tomographic images of the occiput to the C3. The ligaments were modeled with nonlinear spring elements. The model was validated for axial rotation, flexion, extension, lateral bending, and tension for 1.5 Nm, 10 Nm, and 1500 N. A material property sensitivity study was conducted for the ligaments. RESULTS: The model correlated with experimental data for all load cases. Moments of 1.5 Nm produced joint rotations of 3 degrees to 23 degrees depending on loading direction. The parameter study confirmed that the mechanical properties of the upper cervical ligaments play an important role in spinal kinematics. The capsular ligaments had the largest impact on spinal kinematics (40% change). CONCLUSIONS: The anatomic detailed finite element model of the upper cervical spine realistically simulates the complex kinematics of the craniocervical region. An injury that changes the material characteristics of any spinal ligament will influence the structural behavior of the upper cervical spine.

Adult↗
PubMed2000

Comparison of the biomechanical properties of rottweiler and racing greyhound cranial cruciate ligaments.

An in vitro study of rottweiler and racing greyhound cranial cruciate ligaments revealed that the rottweiler ligaments had a significantly greater cross-sectional area at their distal attachments. Mechanical testing showed that the ultimate load related to body mass was significantly higher in the extended racing greyhound stifle during cranial tibial loading to failure, as were linear stiffness, tensile strength and tangent modulus. During ligament axis loading to failure, the only significant difference in structural and mechanical properties recorded between the two breeds was a greater ultimate strain for the greyhound ligament with the stifle joint flexed. Energy absorbed by the ligament complex at failure during cranial tibial loading was twice that for ligament axis loading for both breeds. The clinical significance is that the rottweiler cranial cruciate ligament is more vulnerable to damage as it requires half the load per unit body mass that the greyhound requires to cause a rupture.

Animals↗
PubMed2006

Follow-up of posttraumatic ligamentous and meniscal knee lesions detected at MR imaging: systematic review.

PURPOSE: To perform a systematic review of the literature regarding the natural course of ligamentous and meniscal knee lesions detected at magnetic resonance (MR) imaging. MATERIALS AND METHODS: The MEDLINE database was searched from January 1966 to February 2003. Studies were included if all of the following criteria were met: patients had collateral ligament, cruciate ligament, or meniscal lesions; MR imaging was performed in all patients; study included a group and/or subgroup of patients who underwent conservative treatment during follow-up; patients returned to the clinic for follow-up and clinical data or MR imaging outcomes were noted; and article was written in English, Dutch, German, French, Spanish, Italian, Swedish, Danish, or Norwegian. The quality of each study was assessed by using a standardized criteria set, and kappa statistics were used to grade the level of agreement between the two reviewers. Studies with quality scores of 8 or more were designated as high quality. Results were compared with regard to study design and quality scores. RESULTS: The literature search identified 649 articles, and 11 studies (five on posterior cruciate ligament [PCL] injuries, five on anterior cruciate ligament [ACL] injuries, and one on meniscal injuries) met the inclusion criteria. No studies on the follow-up of collateral ligament injuries were identified. Four studies were of high quality, and the kappa value for quality items was 0.80. Between 77% and 93% of the partial or complete PCL ruptures regained continuity. In cases of partial or total ACL rupture, repair of continuity was also possible. A possible association between MR imaging continuity and clinical stability was identified. CONCLUSION: The ACL and PCL can regain continuity after partial or complete rupture. On the basis of this review, no conclusions can be drawn about the natural course of meniscal or collateral ligament injury seen at MR imaging.

Anterior Cruciate Ligament Injuries↗
PubMedDate not supplied

The anterior intermeniscal ligament of the knee. An anatomic study.

The purpose of this study was to identify the presence of the anterior intermeniscal ligament of the knee and to study its attachment patterns and relationships to other anatomic structures within the knee. Fifty unpaired cadaveric knees were dissected. An identifiably distinct anterior intermeniscal ligament was found in 47 specimens (94%). The average length was 33 mm and the average midsubstance width was 3.3 mm. The average perpendicular distance from the anterior intermeniscal ligament to the anterior margin of the tibial insertion of the anterior cruciate ligament was 7.8 mm (range, 2.0 to 13.5). The anterior intermeniscal ligament was the primary attachment for the anterior horn of the medial meniscus in 12 knees (24%); 7 knees (14%) had no tibial insertion and 5 knees (10%) had only a fine fascial tibial connection. Successful arthroscopic evaluation, surgical repair, and meniscal allograft reconstruction can be enhanced by a precise knowledge of the anterior intermeniscal ligament anatomy, especially when identifying the various insertion patterns of the anterior horn of the medial meniscus. A correct understanding of these patterns is helpful for avoiding patient injury during surgical procedures (particularly arthroscopic ACL reconstructions) performed in close proximity to the anterior intermeniscal ligament of the knee.

Adult↗