Long-term cyclical in vivo loading increases cartilage proteoglycan content in a spatially specific manner: an infrared microspectroscopic imaging and polarized light microscopy study

Table 1 Proteoglycan content in cartilage of cyclically loaded rabbit metacarpophalangeal joints and their contra-lateral controls

Rabbit no.	Control PG^a (absorbance)	Loaded PG (absorbance)	Difference
1	2.1	7.0	4.9
2	2.1	2.6	0.5
3	6.5	10.3	3.8
4	5.2	6.5	1.3
5	4.6	6.0	1.4
6	6.3	6.9	0.6
Mean	4.4	6.5	2.1
SD	1.9	2.4	1.8
Significance^b			0.03

^aPG content was measured as the mean integrated PG peak (1,185 - 960 cm^-1) value from the Fourier Transform Infrared spectra; ^bstatistical significance was calculated using the two-tailed, paired Student t test (α = 0.05). PG, proteoglycan; SD, standard deviation.