The effects of exercise therapy on knee joint biomechanics during walking in patients with knee osteoarthritis: secondary outcome analyses from a randomized controlled trial

Abstract

Purpose: Exercise is recommended as a cornerstone in the non-pharmacological management of knee OA in order to improve mobility, pain, and function. Besides aiming at pain reduction, neuromuscular exercise programs for knee OA have a specific aim of optimization of the knee joint movements related to walking, while the effects on knee joint biomechanics of these exercises remain to be clarified. The objective of this analysis was to assess the effects of a neuromuscular and individualized exercise program on knee joint biomechanics during walking in patients with knee OA. Methods: This was a randomized trial with blinded outcome assessors (NCT01545258). Participants were randomly assigned (1:1) to 12 weeks of facility-based functional and individualized neuromuscular exercise therapy (ET), 3 sessions per week supervised by trained physical therapists, or a no attention control group (CG). To assess knee joint biomechanics during walking, 3-dimensional gait analyses were used, from which self-selected walking speeds, sagittal knee joint angles and internal knee joint moments were extracted. The pain subscale of the KOOS was used to assess the effects on pain. According to the protocol the analyses were based on the ‘Per-Protocol’ population, defined as participants following the protocol with complete and valid gait analyses. Analyses of covariance adjusting for the level at baseline were used to determine differences between groups (95% confidence intervals) in the changes from baseline at follow-up. Results: 60 participants were randomized to ET (n= 31) or CG (n=29). In the ET group, 1 participant had an invalid baseline gait analysis and 6 participants were lost to follow-up; in the CG 1 participant had invalid gait analysis at baseline, 4 were lost, 1 violated the protocol (exercise outside study), and 1 had invalid gait analysis at follow-up. Thus per protocol population included 46 participants (24 ET/22 CG). Summaries of baseline charateristics and KOOS pain (with changes) are given in table 1. Baseline values and changes in knee joint biomechanics during walking are presented in table 2. Besides a statistically significant group difference in the change from baseline in 2nd peak knee flexor moment (late stance), there were no group differences in the changes in knee joint biomechanics during walking (table). Conclusions: A 12-week supervised individualized neuromuscular exercise program has no effect on knee joint biomechanics during walking, except for a slight difference in the change in the knee flexor moment during late stance, indicating an increased moment in the ET. These results indicate that beneficial effects of neuromuscular exercise therapy on pain are not mediated through altered knee joint biomechanics during walking.Table 1Control group (n=22)Exercise group (n=24)-BaselineBaselineMean(SD)Mean(SD)Age, yr61.4(7.2)64.9(9.1)--Female sex, no. (%)16(73%)22(92%)--Height, m1.71(0.09)1.69(0.08)--Weight, kg83.2(15.7)83.1(14.0)--Body Mass index, kg/m228.4(4.6)29.1(4.1)-Baseline Mean (SD)Mean Change(95% CI)Baseline Mean (SD)Mean Change(95% CI)Mean difference (95%CI)PKOOS pain, 0-10059.2 (12.8)−1.1 (−4.9:2.6)63.6 (17.6)6.3 (2.7:9.9)−7.4 (−12.7:−2.2)0.006 Open table in a new tab Table 2Knee biomechanics during walkingControl group (n=22)Exercise group (n=24)Group differenceBaselineChangeBaselineChangeKnee biomechanics variableMean (SD)Mean (95% CI)Mean (SD)Mean (95% CI)Mean (95% CI)PKnee angle at heel strike, deg12.2 (5.7)1.3 (−1.3:3.9)13.8 (5.9)−0.2 (−2.8:2.3)1.5 (2.1:5.2)0.411st Knee flexion angle (early stance), deg23.1 (6.2)1.7 (−0.8:4.2)25.8 (7.6)−1.2 (−3.6:1.3)2.9 (−0.7:6.4)0.11Midstance knee extension angle, deg6.2 (6.3)1.1 (−1.6:3.7)10.1 (7.0)−1.3 (−3.8:1.3)2.3 (−1.4:6.1)0.22Swing phase peak flexion angle, deg59.5 (8.9)−0.6 (−3.8:2.7)61.4 (9.4)−1.1 (−4.2:2.1)0.5 (−4.0:5.1)0.811st peak knee extensor moment(early stance), Nm/Kg0.80 (0.25)0.04 (−0.10:0.180.65 (0.22)−0.01 (−0.15:0.12)0.05 (−0.14:0.25)0.592nd peak knee flexor moment(late stance), Nm/Kg−0.14 (0.16)0.05 (−0.02:0.11)−0.03 (0.16)−0.5 (−0.11:0.01)0.10 (0.01:0.19)0.041st peak knee adductor moment(early stance), Nm/Kg0.67 (0.25)0.05 (−0.03:0.12)0.65 (0.22)0.06 (−0.01:0.13)−0.01 (−0.11:0.09)0.842nd peak knee adductor moment(late stance), Nm/Kg0.50 (0.23)0.07 (0.01:0.014)0.44 (0.18)0.09 (0.02:0.16)−0.02 (−0.12:0.08)0.72Knee abductor angular impulse, Nm*s/kg24.7 (11.4)2.91 (−0.60:6.41)23.2 (9.4)3.09 (−0.27:6.45)−0.18 (−5.04:4.58)0.941st peak knee resultant moment (early stance), Nm/Kg1.04 (0.26)0.05 (−0.05:0.15)1.11 (0.29)0.04 (−0.06:0.14)0.01 (−0.14:0.15)0.912nd peak knee resultant moment (late stance), Nm/Kg0.58 (0.17)0.04 (−0.02:0.10)0.56 (0.12)0.06 (0.01:0.11)−0.02 (−0.10:0.06)0.59Walking speed, m/s1.36 (0.14)−0.05 (−0.14:0.04)1.35 (0.27)−0.03 (−0.12:0.06)−0.02 (−0.15:0.11)0.79 Open table in a new tab