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Spatial distribution and orientation of dermatan sulfate in human medial collateral ligament.

ABSTRACT: The proteoglycan decorin and its associated glycosaminoglycan (GAG), dermatan sulfate (DS), regulate collagen fibril formation, control fibril diameter, and have been suggested to contribute to the mechanical stability and material properties of connective tissues. The spatial distribution and orientation of DS within the tissue are relevant to these mechanical roles, but measurements of length and orientation from 2D transmission electron microscopy (TEM) are prone to errors from projection. The objectives of this study were to construct a 3D geometric model of DS GAGs and collagen fibrils, and to use the model to interpret TEM measurements of the spatial orientation and length of DS GAGs in the medial collateral ligament of the human knee. DS was distinguished from other sulfated GAGs by treating tissue with chondroitinase B, an enzyme that selectively degrades DS. An image processing pipeline was developed to analyze the TEM micrographs. The 3D model of collagen and GAGs quantified the projection error in the 2D TEM measurements. Model predictions of 3D GAG orientation were highly sensitive to the assumed GAG length distribution, with the baseline input distribution of 69+/-23 nm providing the best predictions of the angle measurements from TEM micrographs. The corresponding orientation distribution for DS GAGs was maximal at orientations orthogonal to the collagen fibrils, tapering to near zero with axial alignment. Sulfated GAGs that remained after chondroitinase B treatment were preferentially aligned along the collagen fibril. DS therefore appears more likely to bridge the interfibrillar gap than non-DS GAGs. In addition to providing quantitative data for DS GAG length and orientation in the human MCL, this study demonstrates how a 3D geometric model can be used to provide a priori information for interpretation of geometric measurements from 2D micrographs.

SUBMITTER: Henninger HB

PROVIDER: S-EPMC2814165 | biostudies-literature | 2007 Apr

REPOSITORIES: biostudies-literature

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Spatial distribution and orientation of dermatan sulfate in human medial collateral ligament.

Henninger Heath B HB Maas Steve A SA Underwood Clayton J CJ Whitaker Ross T RT Weiss Jeffrey A JA

Journal of structural biology 20061021 1

The proteoglycan decorin and its associated glycosaminoglycan (GAG), dermatan sulfate (DS), regulate collagen fibril formation, control fibril diameter, and have been suggested to contribute to the mechanical stability and material properties of connective tissues. The spatial distribution and orientation of DS within the tissue are relevant to these mechanical roles, but measurements of length and orientation from 2D transmission electron microscopy (TEM) are prone to errors from projection. Th ...[more]

PMID: 17150374

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Project description:PurposeTo quantify intraoperative joint space widening afforded by the outside-in, percutaneous release of the medial collateral ligament (MCL) and to evaluate its impact on medial compartment width and functional outcomes at 6-week follow-up for patients undergoing a partial medial meniscectomy without postoperative bracing.MethodsPatients with posteromedial meniscus tears and no evidence of ipsilateral knee pathology, undergoing partial medial meniscectomy, were enrolled. Intraoperatively, medial compartment width was quantified with fluoroscopy before and after the percutaneous MCL release with an 18-gauge spinal needle proximal to the joint line. At 6-week follow-up, valgus stress radiographs re-evaluated medial compartment width. International Knee Documentation Committee (IKDC) and Patient-Reported Outcomes Measurement Information System (PROMIS) scores were completed preoperatively and at 6-week follow-up to evaluate functional outcomes. A paired sample t test performed at a 95% confidence interval (CI) was used to compare these variables.ResultsForty-two patients, mean (± standard deviation) age 55.3 ± 10.7 years, were available for analysis of intraoperative medial compartment widening. Medial compartment width increased from 5.95 ± 1.32 to 11.09 ± 1.74 mm intraoperatively after MCL release. At 6-week follow-up, radiographic assessment demonstrated a mean medial compartment width of 5.85 ± .99 mm, which represented an insignificant change compared with the preoperative value (CI -0.68 to .33, P = .474). PROMIS and IKDC scores significantly improved from baseline, with increases of 6.9 ± 12.4 (CI 2.0 to 11.8, P = .008) and 11.7 ± 17.8 (CI 4.7 to 18.8, P = .002), respectively.ConclusionsPercutaneous MCL release during knee arthroscopy improves visualization and facilitates instrumentation by providing an almost 2× wider working space within the medial tibiofemoral joint. In this study, the performance of percutaneous MCL release did not result in any complications. Radiographic and clinical resolution of iatrogenic laxity was demonstrated by 6-weeks postoperatively, without the use of postoperative bracing.Level of evidenceIV, therapeutic case series.

Dataset Information

Spatial distribution and orientation of dermatan sulfate in human medial collateral ligament.

Publications

Spatial distribution and orientation of dermatan sulfate in human medial collateral ligament.

Similar Datasets

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