PHYSICAL-PROPERTIES OF RABBIT ARTICULAR-CARTILAGE AFTER TRANSECTION OF THE ANTERIOR CRUCIATE LIGAMENT

The effect of unilateral transection of the anterior cruciate ligament on the confined compression and swelling properties of the distal fem oral articular cartilage of skeletally mature rabbits at 9 weeks after surgery was determined. Gross morphological grading of the transected and contralateral control distal femora stained with India ink confir med that cartilage degeneration had been induced by ligament transecti on. Osteochondral cores, 1.8 mm in diameter, were harvested from the m edial femoral condyles. The modulus, permeability, and electrokinetic (streaming potential) coefficient of the articular cartilage of the os teochondral cores were assessed by confined compression creep experime nts. The properties (mean +/- SD) of control cartilage were: confined compression modulus, 0.75 +/- 0.28 MPa; hydraulic permeability, 0.63 /- 0.28 x 10(-15) m(2)/Pasec; and electrokinetic coefficient, 0.16 +/ - 0.31 x 10(-9) V/Pa. In transected knees, the modulus was reduced by 18% (p = 0.04), while the permeability and electrokinetic coefficient were not detectably altered. The change in modulus was accompanied by a trend (p = 0.07) toward a decrease (-11%) in the glycosaminoglycan d ensity within the tissue, a significant increase (p < 0.001) in the wa ter content of the cartilage after equilibration in Ix phosphate buffe red saline from 70.3 +/- 4.1% in control knees to 75.2 +/- 4.0% in tra nsected knees, and little further swelling after tissue equilibration in hypotonic saline. The compressive modulus of the cartilage from bot h control and transected knees was positively correlated with the dens ity of tissue glycosaminoglycan. The alterations in the physical prope rties of the articular cartilage after transection of the anterior cru ciate ligament in the rabbit show trends similar to those observed in human and other animal models of osteoarthritis and provide further su pport for the use of this model in the study of cartilage degeneration .