Calcium pyrophosphate dehydrate crystal deposition in the ligamentum flavum of the cervical spine: histopathological and immunohistochemical findings.
OBJECTIVE
To investigate the histopathological and immunohistochemical properties of degenerative changes in the ligamentum flavum of the cervical spine with calcium crystal deposition.


METHODS
Sections of the calcified ligamentum flavum harvested from 26 patients who required cervical decompression were examined by scanning electron microscopy (SEM), energy dispersive X-ray microanalysis, immunohistochemical staining [for transforming growth factor (TGF)-Beta, vascular endothelial growth factor (VEGF), Sox9, and Msx2] and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labelling (TUNEL) method (for cell apoptosis).


RESULTS
Energy dispersive x-ray microanalysis and SEM confirmed the deposited calcium to be calcium pyrophosphate dihydrate (CPPD) crystals. The calcified ligamentum flavum showed disorganisation of the elastic fibre bundles together with increased collagen fibrils in the matrix. Abundant hypertrophic chondrocytes were noted around the calcified lesions, which were strongly immunoreactive to TGF-Beta and VEGF. Staining for Sox9 was positive in metaplastic chondrocytes but negative in hypertrophic chondrocytes. Both chondrocytes and mesenchymal cells were positive for Msx2. TUNEL-positive hypertrophic chondrocytes were significantly more noticeable in nodular than diffusely scattered type of CPPD deposition.


CONCLUSIONS
Calcium crystal deposition in the cervical ligamentum flavum seems to progress with reduction in elastic fibres, increase in collagen fibrils in the matrix, and migration of metaplastic hypertrophic chondrocytes, whose differentiation is controlled by cytokines and transcriptional factors, and potentially regulate crystal formation. The presence of abundant TUNEL-positive hypertrophic chondrocytes around CPPD deposition suggests that materials from apoptotic cells play some role in crystal deposition.
Mwaka
E S
ES
Department of Orthopaedics and Rehabilitation Medicine, Faculty of Medical Sciences, the University of Fukui, Fukui 910-1193, Japan.
Yayama
T
T
Uchida
K
K
Kobayashi
S
S
Kokubo
Y
Y
Nakajima
H
H
Sato
R
R
Orwotho
N T
NT
Baba
H
H
D000368:Aged; D000369:Aged, 80 and over; D002131:Calcium Pyrophosphate / Q000378:metabolism*; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D019902:Chondrocytes / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D003460:Crystallization; D019299:Decompression, Surgical; D004547:Elastic Tissue / Q000648:ultrastructure; D004577:Electron Probe Microanalysis; D005260:Female; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D017843:Ligamentum Flavum / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D055758:SOX9 Transcription Factor / Q000378:metabolism; D013117:Spinal Cord Compression / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D016212:Transforming Growth Factor beta / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D018398:Homeodomain Proteins; C084119:MSX2 protein; D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human; D016212:Transforming Growth Factor beta; D042461:Vascular Endothelial Growth Factor A; D002131:Calcium Pyrophosphate