Neurovascular invasion at the osteochondral junction and in osteophytes in osteoarthritis.
BACKGROUND
Normal adult articular cartilage is thought to be avascular and aneural.


OBJECTIVE
To describe neurovascular structures at the osteochondral junction and in osteophytes in tibiofemoral osteoarthritis (OA) displaying a range of severity of cartilage changes.


METHODS
Articular surfaces were obtained from 40 patients at total knee joint replacement surgery for tibiofemoral OA (TKR) and seven patients post mortem (PM). Antibodies directed against CD34 (vascular endothelium), protein gene product 9.5 (pan-neuronal marker), substance P and calcitonin gene-related peptide (sensory nerves) and C-flanking peptide of neuropeptide Y (sympathetic nerves) were used to localise blood vessels and nerves by immunohistochemistry. Severity of OA cartilage changes was graded histologically.


RESULTS
TKR and PM samples displayed a range of OA cartilage changes including tidemark breaching by vascular channels. Sympathetic and sensory nerves were both present within vascular channels in the articular cartilage, in both mild and severe OA. Perivascular and free nerve fibres, and nerve trunks were observed within the subchondral bone marrow and within the marrow cavities of osteophytes. Sensory and sympathetic nerves displayed similar distributions in each region studied.


CONCLUSIONS
Vascularisation and the associated innervation of articular cartilage may contribute to tibiofemoral pain in OA across a wide range of structural disease severity.
Suri
Sunita
S
Academic Rheumatology, University of Nottingham, City Hospital, Hucknall Road, Nottingham, Notts NG5 1PB, UK.
Gill
Sarah E
SE
Massena de Camin
Sally
S
Wilson
Deborah
D
McWilliams
Daniel F
DF
Walsh
David A
DA
D000368:Aged; D000369:Aged, 80 and over; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002358:Cartilage, Articular / Q000098:blood supply* / Q000294:innervation; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000098:blood supply* / Q000294:innervation; D008297:Male; D009389:Neovascularization, Pathologic / Q000209:etiology / Q000473:pathology*; D009412:Nerve Fibers / Q000473:pathology; D020370:Osteoarthritis, Knee / Q000150:complications / Q000473:pathology*; D017933:Peripheral Nervous System / Q000378:metabolism / Q000473:pathology; D012720:Severity of Illness Index; D013373:Substance P / Q000378:metabolism; D043222:Ubiquitin Thiolesterase / Q000378:metabolism
C482860:UCHL1 protein, human; D013373:Substance P; D043222:Ubiquitin Thiolesterase; D015740:Calcitonin Gene-Related Peptide