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PubMed2004

Cervical spine ligament injury during simulated frontal impact.

STUDY DESIGN: The supraspinous and interspinous ligaments, ligamentum flavum, and capsular and posterior longitudinal ligament strains were monitored during simulated frontal impact of whole cervical spine specimens with muscle force replication and compared with corresponding physiologic strain limits. OBJECTIVES: To quantify the strains in the cervical spine ligaments during simulated frontal impact and investigate injury mechanisms. SUMMARY OF BACKGROUND DATA: Clinical and biomechanical studies have documented injuries to cervical spine ligaments during frontal impact. There are no biomechanical studies investigating subfailure injury mechanisms to these ligaments during simulated frontal impacts of increasing severity. METHODS: The whole cervical spine with muscle force replication model and a bench-top sled were used to simulate frontal impacts at 4, 6, 8, and 10 g horizontal accelerations of the T1 vertebra. The peak ligament strains during frontal impacts were compared with physiologic strain limits determined during intact flexibility testing. RESULTS: Significant increases (P < 0.05) in the supraspinous and interspinous ligaments and the ligamentum flavum strains beyond physiologic limits were observed throughout the cervical spine, with the highest strains occurring at C3-C4. Significant increases were observed in the capsular ligament strains only during the 10 g impact, whereas the posterior longitudinal ligament strains did not exceed physiologic limits. CONCLUSIONS: The supraspinous and interspinous ligaments and the ligamentum flavum may be at risk for injury due to excessive strains during frontal impacts.

Aged↗
PubMed2000

Geometric and mechanical properties of human cervical spine ligaments.

This study characterized the geometry and mechanical properties of the cervical ligaments from C2-T1 levels. The lengths and cross-sectional areas of the anterior longitudinal ligament, posterior longitudinal ligament, joint capsules, ligamentum flavum, and interspinous ligament were determined from eight human cadavers using cryomicrotomy images. The geometry was defined based on spinal anatomy and its potential use in complex mathematical models. The biomechanical force-deflection, stiffness, energy, stress, and strain data were obtained from 25 cadavers using in situ axial tensile tests. Data were grouped into middle (C2-C5) and lower (C5-T1) cervical levels. Both the geometric length and area of cross section, and the biomechanical properties including the stiffness, stress, strain, energy, and Young's modulus, were presented for each of the five ligaments. In both groups, joint capsules and ligamentum flavum exhibited the highest cross-sectional area (p < 0.005), while the longitudinal ligaments had the highest length measurements. Although not reaching statistical significance, for all ligaments, cross-sectional areas were higher in the C5-T1 than in the C2-C5 group; and lengths were higher in the C2-C5 than in the C5-T1 group with the exception of the flavum (Table 1 in the main text). Force-deflection characteristics (plots) are provided for all ligaments in both groups. Failure strains were higher for the ligaments of the posterior (interspinous ligament, joint capsules, and ligamentum flavum) than the anterior complex (anterior and posterior longitudinal ligaments) in both groups. In contrast, the failure stress and Young's modulus were higher for the anterior and posterior longitudinal ligaments compared to the ligaments of the posterior complex in the two groups. However, similar tendencies in the structural responses (stiffness, energy) were not found in both groups. Researchers attempting to incorporate these data into stress-analysis models can choose the specific parameter(s) based on the complexity of the model used to study the biomechanical behavior of the human cervical spine.

Analysis of Variance↗
PubMed1991

Normal contact of elastic spheres with two elastic layers as a model of joint articulation.

An analytical model of two elastic spheres with two elastic layers in normal, frictionless contact is developed which simulates contact of articulating joints, and allows for the calculation of stresses and displacements in the layered region of contact. Using various layer/layer/substrate combinations, the effects of variations in layer and substrate properties are determined in relation to the occurrence of tensile and shear stresses as the source of crack initiation in joint cartilage and bone. Vertical cracking at the cartilage surface and horizontal splitting at the tidemark have been observed in joints with primary osteoarthritis. Deep vertical cracks in the calcified cartilage and underlying bone have been observed in blunt trauma experiments. The current model shows that cartilage stresses for a particular system are a function of the ratio of contact radius to total layer thickness (a/h). Surface tension, which is observed for a/h small, is alleviated as a/h is increased due to increased load, softening and/or thinning of the cartilage layer. Decreases in a/h due to cartilage stiffening lead to increased global compressive stresses and increased incidence of surface tension, consistent with impact-induced surface cracks. Cartilage stresses are not significantly affected by variations in stiffness of the underlying material. Tensile radial strains in the cartilage layer approach one-third of the normal compressive strains, and increase significantly with cartilage softening. For cases where the middle layer stiffness exceeds that of the underlying substrate, tensile stresses occur at the base of the middle layer, consistent with impact induced cracks in the zone of calcified cartilage and subchondral bone. The presence of the superficial tangential zone appears to have little effect on underlying cartilage stresses.

Cartilage, Articular↗
PubMed1993

Biomechanics of diarthrodial joints: a review of twenty years of progress.

A survey of some of the advances made over the past twenty years in understanding diarthrodial joint biomechanics is presented. Topics covered in this review include: biotribology (i.e., friction, lubrication and wear of diarthrodial joints); contact area determinations; stereophotogrammetric rendering of articular surfaces; deformational field analysis using canonical problems; and finite element formulations for both infinitesimal and finite deformations of biphasic materials and precise anatomic surfaces. Suggestions are made for future research directions as well.

Animals↗
PubMed1993

Review article: MRI of the knee.

The inherent vulnerability of the knee to injury and degenerative change means that there is a major requirement for an imaging technique capable of assessing such damage accurately, rapidly and non-invasively. Over a relatively short time magnetic resonance imaging (MRI) has emerged as the technique of choice in the assessment of internal derangement of the knee. The present review describes the wide application of MRI to the knee and considers the position of MRI in relation to other diagnostic methods.

Cartilage, Articular↗
PubMed1999

The intercruciate band of the human knee. An anatomical and histological study.

Thirty cruciate ligaments were retrieved from either cadavers or limbs which had been amputated. Each specimen was sectioned and stained to demonstrate the presence of collagen, nerves and vessels. All 30 specimens contained an interconnecting band of collagen fibres between the anterior and posterior cruciate ligaments. Vascular structures were present in all specimens and nerve fibres were identified in 26 (86%). We have called this structure the 'intercruciate band'. The anterior and posterior cruciate ligaments should no longer be thought of in isolation, but together as a 'cruciate complex'.

Anterior Cruciate Ligament↗
PubMed1994

Preoperative staging of osteosarcoma: efficacy of MR imaging in detecting joint involvement.

OBJECTIVE: Selecting the appropriate surgical procedure for treatment of patients with osteosarcoma requires accurate preoperative evaluation of tumor extent. Establishing the presence or absence of joint involvement is particularly important. Accordingly, we studied the efficacy of MR imaging for detecting joint involvement in 46 patients with osteosarcoma around joint spaces. SUBJECTS AND METHODS: Preoperative MR examinations were performed in 46 consecutive patients with osteosarcoma whose tumors were located around the knee (n = 33), the hip (n = 8), or the shoulder (n = 5). T2-weighted and unenhanced and contrast-enhanced T1-weighted spin-echo MR images were obtained for all patients. We assessed the presence or absence of tumor invasion of the intracapsular-intrasynovial joint space, either by disruption of the joint capsule or by intraarticular destruction of the cortical bone and articular cartilage or the intracapsular-extrasynovial cruciate ligaments of the knee. All patients subsequently had surgery. The MR findings were correlated with findings from macroscopic and microscopic pathologic examinations. RESULTS: All 10 patients who subsequently proved to have tumor involvement of the joint were correctly identified (sensitivity, 100%). The tumor involved the knee joint in seven patients, the hip joint in two, and the shoulder joint in one. However, the MR diagnosis was false-positive in another 11 patients who did not have joint involvement at surgery (specificity, 69%). In the knee, MR imaging was more accurate in identifying tumor extension to the cruciate ligaments than to the intrasynovial joint space. Post-contrast T1-weighted images were most useful in detecting joint involvement. CONCLUSION: MR imaging is highly sensitive for detecting joint invasion of osteosarcoma. However, false-positive diagnoses may lead to overstaging of tumor and result in unnecessarily radical surgical procedures.

Adolescent↗
PubMed2001

Microstructural morphology in the transition region between scar and intact residual segments of a healing rat medial collateral ligament.

This study used a rat model to investigate the microstructural organization of collagen through the transition from scar to intact residual segments of a healing medial collateral ligament (MCL). Twenty-two male retired breeder Sprague-Dawley rats were randomly separated into two groups. Eleven underwent surgical transections of both MCLs and were allowed unrestricted cage activity until euthanized two weeks post surgery. The remaining eleven rats were used as normal controls. All 44 MCLs were harvested including intact femoral and tibial insertions and prepared for scanning electron microscopy (SEM) imaging. At harvest the scar region in the healing ligaments was more translucent than the normal tissue. Ligaments were viewed from femoral to tibial insertions at magnifications of 100X through 20,000X. Tissue away from the scar region in the transected MCLs was indistinguishable from normal tissue in uninjured ligaments. Collagen fibers and fibrils in these tissues were more aligned along the longitudinal axis of the ligament than in the scar tissue. Continuity of collagen fibers and fibrils were consistently observed from the residual portions of the transected ligament through the scar region. Bifurcations/fusions, but no anastomoses, in fibers and fibrils were observed in both normal and scar tissues of ligaments. Qualitatively, bifurcations were encountered more frequently in scar tissue. In the transition region, larger diameter fibers from the residual tissue bifurcated into smaller diameter fibrils in the scar. This connection between larger diameter and smaller diameter fibers and fibrils indicates that bifurcations/fusions are likely to be the dominant way in which force is transmitted from a region with larger fibrils (residual ligament) into and through a region with smaller fibrils (scar).

Animals↗
PubMed1992

Wrist arthroscopy: an overview.

An introductory overview of wrist arthroscopy is presented. The relevant anatomy and pathology of the wrist are reviewed, with special emphasis on the triangular fibrocartilage complex. Operative technique and equipment are described, and operative indications are presented. The role of diagnostic arthroscopy is discussed and comparison is made to arthrography in terms of diagnostic efficacy. Some future directions for wrist arthroscopy are presented.

Arthrography↗
PubMed1990

Arthroscopic techniques to improve access to posterior meniscal lesions.

Unsatisfactory results following partial meniscectomy and problems related to a retained posterior horn of the medial meniscus are problems often attributed to inadequate arthroscopic partial meniscectomy. Although there are multiple techniques to gain better access to the various compartments in a truly tight knee, most of the problems in obtaining maximum visualization and instrumentation to the posterior aspects of the medial or lateral meniscus can usually be solved by adhering to a strict surgical technique that attempts to control the multiple variables encountered during arthroscopic surgery. These include the use of a tourniquet, leg holder, maximum distention of the knee provided by a large inflow cannula with large-bore tubing connected to 3-L bags, and an 18-gauge needle as a predecessor to the larger arthroscopic instruments. Of utmost importance is establishing the correct portal for the arthroscope, and it is time well spent at the beginning of the surgical procedure to verify the proper location of the arthroscope and not simply insert the arthroscope "a thumb-breadth above the joint line." Once these variables have been controlled, one can usually visualize and perform arthroscopic surgery on most meniscal lesions with minimal scuffing to the articular surfaces.

Arthroscopy↗
PubMed1987

[Spondylarthropathies or ossifying polyenthesitis. Scintigraphic and scanographic evidence].

Ossifying enthesites present an undeniable diagnostic value in every chronic inflammatory rheumatism at an early stage, not only in adults but also in children. Bony scintigraphy discovers them in most localizations at a preradiological stage, as soon as they cause pain. The scanner examination enables to follow the anatomical evolution of the ossifications. It is perfectly suitable for the study of sacro-iliac and interapophyseal joints. Ossifying enthesites, the evolution of which spreads over several years, often depend on mechanical, professional or athletic constraints. Ossifying enthesitis is a common characteristics of "classic" spondylo-arthropathies which are all ossifying polyenthesites: ankylosing spondylarthritis, psoriasic rheumatism, rheumatism of enteropathies, Fiessinger-Leroy-Reiter syndrome and juvenile spondylo-arthropathies.

Adult↗
PubMed1987

[Nuclear magnetic resonance tomography anatomy of the knee and ankle joints].

Soft tissue and osseous structures of joints can be differentiated by magnetic resonance tomography. Knee and ankle joints of three volunteers were systematically examined using a head coil at 1.5 Tesla and spin echo mode. Slice thickness was 5 mm. The anatomical details which could be visualized are described and directions for the most useful slices are indicated.

Adipose Tissue↗
PubMed1979

Z-plasty lateral retinacular release for the treatment of patellar compression syndrome.

Lateral retinacular release by Z-plasty technique in selected patients provides a relatively simple procedure for relief of symptoms in patellar compression syndrome and is a satisfactory initial surgical procedure in cases not responding to conservative therapy. Unfortunately, there is no specific symptom complex, physical finding, radiographic finding, or arthrotomy finding which delineates the patient with patellar compression syndrome who will benefit from an isolated lateral retinacular release. Some patients may require further extensor mechanism realignment procedures (e.g., medial capsular reefing, tibial tubercle transplantation, tibial tubercle elevation, etc.) to relieve the aggravating symptoms of parapatellar and retropatellar pain.

Adolescent↗