V.P. Karjalainen , I. Hellberg , A. Turkiewicz , B. Shakya , N. Khoshimova , E. Nevanranta , K. Elkhouly , S. Das Gupta , A. Sjögren , M.A.J. Finnilä , P. Önnerfjord , V. Hughes , J. Tjörnstrand , M. Englund , S. Saarakkala
{"title":"EX VIVO IMAGING OF DIFFERENT CALCIFICATION TYPES IN POSTERIOR HORN OF HUMAN MENISCUS USING MICRO-COMPUTED TOMOGRAPHY","authors":"V.P. Karjalainen , I. Hellberg , A. Turkiewicz , B. Shakya , N. Khoshimova , E. Nevanranta , K. Elkhouly , S. Das Gupta , A. Sjögren , M.A.J. Finnilä , P. Önnerfjord , V. Hughes , J. Tjörnstrand , M. Englund , S. Saarakkala","doi":"10.1016/j.ostima.2025.100296","DOIUrl":null,"url":null,"abstract":"<div><h3>INTRODUCTION</h3><div>Meniscal calcifications are known to be associated with OA. Specifically, two types of calcifications have been commonly identified in osteoarthritic knees: basic calcium phosphate (BCP) and calcium pyrophosphate (CPP). However, their pathological significance remains largely unclear. Characterizing differences between the calcification types and their deposition patterns inside the meniscus could help in their identification with <em>in vivo</em> imaging modalities and provide a better understanding of the role of meniscal calcifications in the OA disease process.</div></div><div><h3>OBJECTIVE</h3><div>1) Identify the two different types of calcifications in human meniscus <em>ex vivo</em> in 3D using µCT; 2) Describe the different deposition patterns observed in BCP and CPP calcifications.</div></div><div><h3>METHODS</h3><div>From the MENIX biobank in Lund, Sweden, we collected 82 posterior horns of medial and lateral menisci from 20 total knee replacement (TKR) patients and 21 deceased donors (50/50% female/male, average age 71 years) for the study. A 5-mm-thick subsection was dissected from the posterior horn, fixed in formalin, dehydrated, and treated with hexamethyldisilazane (HMDS) before air-drying at room temperature overnight. Subsequently, the HMDS-treaded section was imaged with a desktop µCT imaging (SkyScan 1272, Bruker, micro-CT) with the following settings: 60 kV, 166 µA, 2.0 µm voxel size, 3500 ms exposure time, random movement 25 voxels, and without an additional filter. Two different image reconstruction settings were used to maximize the image quality of meniscal soft tissue and calcifications. Pieces of meniscus adjacent to the µCT underwent histological processing and Alizarin Red staining. Calcification types from the histological sections were identified using Raman micro-spectroscopy.</div></div><div><h3>RESULTS</h3><div>We successfully imaged both meniscal calcification types together with soft tissue in 3D using high-resolution µCT (Figure 1). Based on Raman spectral analysis, out of the 82 menisci, 39 had at least one calcification: 28 had BCP calcifications, 8 had CPP calcifications, and 3 had both. In µCT, BCP calcifications were quantitatively denser, morphologically sharper, more punctuated, smaller in size as well as number, and more spherical than CPPs. Unlike CPPs, BCPs were mainly deposited in the periphery of meniscal tissue, inside complex 3D tears or fibrillations. In contrast, the CPP calcifications formed long rod-like structures, mainly inside the meniscal tissue.</div></div><div><h3>CONCLUSION</h3><div>Based on the 3D µCT images, BCP calcifications were not found inside the meniscal tissue but in the peripheral area. This could suggest that larger clusters of BCP calcifications found in the meniscus come from the synovial fluid and possibly originate from articular cartilage or bone. Meanwhile, the likely place for CPPs to accumulate and expand within the meniscal tissue is in the fluid channels that follow the circumferential collagen fiber bundles, where they fill the cavity of the channel to form rod-like morphology and have a continuous supply of calcium and other constituents. Additionally, vascular walls were observed to accumulate calcifications, supported by hollow rod-shaped structures that do not follow the circumferential fibers. Potentially, after tearing and degeneration of the meniscus, CPPs may start to accumulate on the surfaces and tears of the meniscus in an amorphous pattern. This qualitative 3D comparison of meniscal calcification patterns may help distinguish them with imaging modalities more easily in the future, as well as provide a better understanding of their role in OA.</div></div>","PeriodicalId":74378,"journal":{"name":"Osteoarthritis imaging","volume":"5 ","pages":"Article 100296"},"PeriodicalIF":0.0000,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Osteoarthritis imaging","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2772654125000364","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
INTRODUCTION
Meniscal calcifications are known to be associated with OA. Specifically, two types of calcifications have been commonly identified in osteoarthritic knees: basic calcium phosphate (BCP) and calcium pyrophosphate (CPP). However, their pathological significance remains largely unclear. Characterizing differences between the calcification types and their deposition patterns inside the meniscus could help in their identification with in vivo imaging modalities and provide a better understanding of the role of meniscal calcifications in the OA disease process.
OBJECTIVE
1) Identify the two different types of calcifications in human meniscus ex vivo in 3D using µCT; 2) Describe the different deposition patterns observed in BCP and CPP calcifications.
METHODS
From the MENIX biobank in Lund, Sweden, we collected 82 posterior horns of medial and lateral menisci from 20 total knee replacement (TKR) patients and 21 deceased donors (50/50% female/male, average age 71 years) for the study. A 5-mm-thick subsection was dissected from the posterior horn, fixed in formalin, dehydrated, and treated with hexamethyldisilazane (HMDS) before air-drying at room temperature overnight. Subsequently, the HMDS-treaded section was imaged with a desktop µCT imaging (SkyScan 1272, Bruker, micro-CT) with the following settings: 60 kV, 166 µA, 2.0 µm voxel size, 3500 ms exposure time, random movement 25 voxels, and without an additional filter. Two different image reconstruction settings were used to maximize the image quality of meniscal soft tissue and calcifications. Pieces of meniscus adjacent to the µCT underwent histological processing and Alizarin Red staining. Calcification types from the histological sections were identified using Raman micro-spectroscopy.
RESULTS
We successfully imaged both meniscal calcification types together with soft tissue in 3D using high-resolution µCT (Figure 1). Based on Raman spectral analysis, out of the 82 menisci, 39 had at least one calcification: 28 had BCP calcifications, 8 had CPP calcifications, and 3 had both. In µCT, BCP calcifications were quantitatively denser, morphologically sharper, more punctuated, smaller in size as well as number, and more spherical than CPPs. Unlike CPPs, BCPs were mainly deposited in the periphery of meniscal tissue, inside complex 3D tears or fibrillations. In contrast, the CPP calcifications formed long rod-like structures, mainly inside the meniscal tissue.
CONCLUSION
Based on the 3D µCT images, BCP calcifications were not found inside the meniscal tissue but in the peripheral area. This could suggest that larger clusters of BCP calcifications found in the meniscus come from the synovial fluid and possibly originate from articular cartilage or bone. Meanwhile, the likely place for CPPs to accumulate and expand within the meniscal tissue is in the fluid channels that follow the circumferential collagen fiber bundles, where they fill the cavity of the channel to form rod-like morphology and have a continuous supply of calcium and other constituents. Additionally, vascular walls were observed to accumulate calcifications, supported by hollow rod-shaped structures that do not follow the circumferential fibers. Potentially, after tearing and degeneration of the meniscus, CPPs may start to accumulate on the surfaces and tears of the meniscus in an amorphous pattern. This qualitative 3D comparison of meniscal calcification patterns may help distinguish them with imaging modalities more easily in the future, as well as provide a better understanding of their role in OA.