We longitudinally followed 237 participants, of whom 7 (3%) did not return at 18 months; 5 had died, and 2 could not be reached. Of the 230 remaining participants, 171 did not have advanced osteoarthritis in any compartment of either knee. Among these 171 participants (126 women, 45 men), mean age (±SD) was 64.0 ± 11.0 years and mean BMI (±SD) was 30.0 ± 5.5 kg/m2. At baseline, no participants had a Kellgren and Lawrence grade of 0 for right knee osteoarthritis severity, 11 had a grade of 1, 110 had a grade of 2, 50 had a grade of 3, and none had a grade of 4. Sixty-three participants had no joint space narrowing in the right knee at baseline, 60 had mild narrowing, 48 had moderate narrowing, and none had severe narrowing. Mean right-limb quadriceps strength (±SD) was 51.8 ± 28.5 ft-lb, and mean laxity (±SD) was 5.32 ± 2.03 degrees. Right knees were varus in 79 participants, valgus in 71 participants, and neutral in 21 participants. No participants had a knee effusion. These assessments were similar in the left knees. All analyses incorporated data from both knees, using generalized estimating equations. We excluded 14 knees that had previously been replaced, leaving 328 knees for analysis.