Redistribution Of Inter-joint Sharing Of The Total Support Moment During Uphill Walking In ACL Deficiency

PURPOSE: The current study aimed to identify the changes in the inter-joint sharing of the total support moment (Ms) for body support during uphill walking in patients with anterior cruciate ligament deficiency (ACLD). METHODS: Thirteen adult patients with ACLD and 13 BMI- and age-matched healthy controls participated in the current study with informed written consent as approved by the IRB. Each subject walked at a preferred speed on a 10-meter walkway of slopes of 3°, 6° and 9°. The 3D motions of the body segments were measured by tracking 39 markers on the body segments using an 8-camera motion analysis system. The ground reaction forces (GRF) were measured simultaneously using three forceplates. The lower-limb joint moments were calculated using inverse dynamics analysis. The Ms was calculated as the sum of the net moments at the hip, knee and ankle in the sagittal plane. The contributions of the individual joints to the peak MS were calculated by dividing the individual joint moment values by the peak value. The Kruskal-Wallis test was performed to compare between groups and the Wilcoxon sign rank test was performed to compare between the sides of the ACLD group (α = 0.05). RESULTS: Compared to the Control, the ACLD group maintained unaltered knee contributions to the total support moment by significantly decreasing contributions of both hips but increasing those of the unaffected ankle, particularly during walking up a slope of 9° (Table 1). CONCLUSION: The current results suggest that during walking up a slope higher than 9° patients with ACLD may maintain unaltered knee contributions to the total support moment for whole-body support by a compensatory mechanism of increasing the ankle plantarflexor moment contributions with decreased contributions of hip extensor moment of both sides. Such a strategy may help reduce the risk of knee instability in ACLD as increased knee extensor moments may increase the anterior pull of the patellar tendon and thus the risk of joint instability. - Individual joint contributions to the peak total support moment (%) during uphill walking. Variables Group Slope angle (°) Main effects 3 6 9 Hip extensor (+)/ flexor (-) ACLD Affected side 66.0 (9.7) 66.8 (9.9) 63.7 (6.5) Pac3 = 0.446, Pac6 = 0.663, P ac9 = 0.019*, Puc3 = 0.231, Puc6 = 0.415, P uc9 = 0.039*, Pau3 = 0.152, Pau6 = 0.221, Pau9 = 0.463 Unaffected side 62.3 (6.5) 63.8 (6.7) 62.7 (6.5) Control 66.8 (8.3) 67.2 (8.0) 69.9 (8.4) Knee extensor (+)/ flexor (-) ACLD Affected side 35.4 (6.8) 35.3 (5.5) 32.9 (7.0) Pac3 = 0.703, Pac6 = 0.415, Pac9 = 0.913, Puc3 = 0.231, Puc6 = 0.355, Puc9 = 0.514, Pau3 = 0.422, Pau6 = 0.807, Pau9 = 0.552 Unaffected side 36.4 (5.0) 35.7 (4.8) 33.7 (4.4) Control 33.8 (6.7) 32.8 (6.9) 32.6 (6.5) Ankle plantarflexor (+)/ dorsiflexor (-) ACLD Affected side -1.4 (12.5) -2.1 (1.2) 3.4 (6.7) Pac3 = 0.480, Pac6 = 0.786, Pac9 = 0.082, Puc3 = 0.514, Puc6 = 0.913, P uc9 = 0.039*, Pau3 = 0.650, Pau6 = 0.972, Pau9 = 0.753 Unaffected side 1.3 (3.7) 0.5 (5.0) 3.6 (4.3) Control -0.6 (5.2) 0.01 (5.0) -2.5 (8.5) This work was supported by grants from the Shuang Ho Hospital (109YSR-04).