Kinematic and dynamic gait compensations resulting from knee instability in a rat model of osteoarthritis

Table 1 Histological grades and measurements

Surgical group	Knee	OARSI Histopathology score (medial tibial plateau, [41])	Lesion size (% of cartilage area)	Affected surface (% of cartilage surface)	Lesion depth (% of cartilage thickness)
Naïve	Left	1.5 ± 1.3	3.8 ± 3.8%	8.5 ± 6.3%	27.9 ± 47.8%
MCL sham	Left	0 ± 0	0 ± 0	0 ± 0	0 ± 0
MMT	Left	1.7 ± 2.1	5.2 ± 6.9%	12.7 ± 18.9%	36.2 ± 44.0%
Naïve	Right	0.5 ± 0.6	1.0 ± 1.4%	2.0 ± 2.6%	4.4 ± 6.2%
MCL sham	Right	0.2 ± 0.4	0.1 ± 0.3%	1.3 ± 3.0%	0.3 ± 0.8%
MMT	Right	4.5 ± 0.8^ab	18.2 ± 6.5%^ab	38.3 ± 15.8%^a	85.5 ± 24.1%^a

Rats with the medial meniscus transection (MMT) surgery had lesions that graded between OARSI rank 4 (erosion) and OARSI rank 5 (denudation) [41]; these lesions ranked significantly higher than histological sections from the contralateral limb (P = 0.031), medial collateral ligament (MCL) sham animals (P = 0.005), and tended to rank higher than naïve controls (P = 0.068). The size of lesion in the operated (right) limb, measured as the approximate percentage of cartilage loss, was larger in rats with MMT surgery than in rats with MCL sham surgery (P = 0.001) or naïve controls (P = 0.003); the size of the lesion in the operated limb of MMT rats also tended to be larger than that found in the contralateral limb control (P = 0.060). The percentage of the cartilage surface affected by the injury was larger in the operated limb of rats with MMT surgery than in contralateral limb controls (P < 0.001) and the limbs of rats with MCL sham surgery (P < 0.001) or naïve control animals (P < 0.001). Likewise, the percentage of the cartilage depth affected by the injury was larger in the operated limb of rats with MMT surgery than in contralateral limb controls (P < 0.010) and the limbs of rats with MCL sham surgery (P < 0.001) or naïve control animals (P < 0.007). Data are presented as mean ± standard deviation. ^aValues that are significantly different at a level of P < 0.05; ^bvalues near significance at a level of 0.1 <P ≤ 0.05.

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