Increased matrix concentrations of IGFBP-5 in cancellous bone in osteoarthritis.
BACKGROUND
In osteoarthritis cancellous bone adapts to meet altered mechanical loading. These changes may be mediated by insulin-like growth factors (IGF-I and IGF-II), but the matrix bound binding protein, IGFBP-5 has not been investigated.


OBJECTIVE
To measure IGF-I, IGF-II, and IGFBP-5 in femoral head bone from non-OA controls and patients with OA, and to relate these to apparent density (rhoA) and elastic modulus (Ec).


METHODS
rhoA, Ec, and IGF system components were measured in cancellous bone from superior and inferior regions of femoral heads from 31 patients with OA and 11 age selected controls.


RESULTS
Ec and rhoA were greater (p<0.05) in the superior region of all femoral heads. In primary OA, rhoA was increased in the inferior region (p<0.05). IGFBP-5 was increased, about twofold, at superior and inferior regions in primary OA (1.60 and 1.54 ng/mg bone, respectively, both p<0.05) and in Paget's disease (2.44 and 1.75 ng/mg bone, both p<0.05) compared with controls (0.73 and 0.95 ng/mg bone). In controls, inverse correlations between IGFBP-5 and both rhoA and Ec at superior (rs = -0.64 and -0.73, both p<0.05) and inferior regions (rs = -0.72, p<0.05 and -0.24 (NS)) were seen, but these were lost in OA.


CONCLUSIONS
IGFBP-5 may modulate cancellous bone formation by negative feedback. In end stage OA this is disrupted, but has little influence on material properties.
Chalres Salt Centre, Robert Jones and Agnes Hunt Orthopaedic Hospital NHS Trust, Oswestry, Shropshire, UK. chris.sharp@rjah.nhs.uk
C A
CA
Sharp
S J
SJ
Brown
M W J
MW
Davie
P
P
Magnusson
S
S
Mohan
D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density; D019245:Compressive Strength; D005260:Female; D005270:Femur Head / Q000737:chemistry; D006801:Humans; D018975:Insulin-Like Growth Factor Binding Protein 5 / Q000032:analysis*; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D007335:Insulin-Like Growth Factor II / Q000032:analysis; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000378:metabolism* / Q000503:physiopathology
D018975:Insulin-Like Growth Factor Binding Protein 5; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II