Table 2.
Strength differences between patients with KOA and control individuals without knee complaints unadjusted and adjusted for age
| Strength Joint Dir | KOA-group | HC-group | SMD | KOA – HC group | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Rn | M (SD) [in Nm/kg unit] | M % d | P-values | |||||||
| Unadj (SD) | Adj M (SD) | Unadj M (SD) | Adj | Unadj | Adj (95% CI) | Adj | Unadj | Adj | ||
| 1 | Hip IR I | 0.74 (0.27) | 0.75 (0.25) | 0.96 (0.21) | 0.94 (0.25) | −0.9 | −0.7 (−1.3, − 0.2) | 22.5 | 0.0009 | 0.0092† |
| 2 | Ankle EV I | 0.19 (0.08) | 0.20 (0.08) | 0.27 (0.07) | 0.26 (0.08) | −1.0 | −0.7 (− 1.3, − 0.2) | 26.1 | 0.0006 | 0.0096† |
| 3 | Hip ER I | 0.25 (0.10) | 0.26 (0.12) | 0.36 (0.13) | 0.35 (0.12) | −0.9 | −0.7 (−1.2, − 0.2) | 29.5 | 0.0008 | 0.013* |
| 4 | Knee EXT I | 1.16 (0.48) | 1.15 (0.46) | 1.46 (0.38) | 1.48 (0.46) | −0.7 | − 0.7 (−1.2, − 0.2) | 25.1 | 0.0103 | 0.012* |
| 5 | Ankle PF I | 0.56 (0.24) | 0.58 (0.25) | 0.75 (0.23) | 0.73 (0.25) | −0.5 | − 0.6 (−1.2, − 0.1) | 22.9 | 0.0029 | 0.073 |
| 6 | Ankle DF I | 0.17 (0.07) | 0.17 (0.08) | 0.23 (0.09) | 0.22 (0.08) | −0.8 | −0.6 (−1.1, − 0.1) | 25.6 | 0.0043 | 0.025* |
| 7 | Ankle INV I | 0.24 (0.10) | 0.25 (0.10) | 0.31 (0.08) | 0.31 (0.10) | −0.8 | −0.6 (−1.1, − 0.1) | 21.4 | 0.0055 | 0.033* |
| 8 | Hip AD U | 0.75 (0.33) | 0.76 (0.31) | 0.93 (0.25) | 0.92 (0.31) | −0.6 | −0.5 (−1.0, 0.0) | 19.0 | 0.0227 | 0.057 |
| 9 | Ankle DF U | 0.17 (0.06) | 0.18 (0.08) | 0.23 (0.08) | 0.22 (0.08) | −0.7 | − 0.5 (−1.0, 0.0) | 20.0 | 0.0096 | 0.021* |
| 10 | Hip AD I | 0.71 (0.27) | 0.72 (0.27) | 0.86 (0.24) | 0.85 (0.27) | −0.6 | − 0.5 (−1.0, 0.0) | 16.6 | 0.0272 | 0.057 |
| 11 | Knee FLX I | 0.59 (0.35) | 0.61 (0.33) | 0.77 (0.28) | 0.76 (0.0.33) | −0.6 | −0.5 (−1.0, 0.1) | 21.9 | 0.0325 | 0.114 |
| 12 | Hip FLX I | 1.15 (0.29) | 1.15 (0.32) | 1.29 (0.31) | 1.29 (0.32) | −0.4 | − 0.4 (−1.0, 0.1) | 11.5 | 0.0749 | 0.256 |
| 13 | Knee EXT U | 1.45 (0.36) | 1.45 (0.44) | 1.64 (0.46) | 1.64 (0.44) | −0.5 | − 0.4 (− 0.9, 0.1) | 11.6 | 0.0877 | 0.120 |
| 14 | Hip EXT I | 1.20 (0.52) | 1.21 (0.52) | 1.44 (0.45) | 1.43 (0.51) | −0.5 | −0.4 (− 0.9, 0.1) | 16.7 | 0.0701 | 0.135 |
| 15 | Hip AB U | 0.85 (0.37) | 0.88 (0.36) | 1.05 (0.33) | 1.02 (0.36) | −0.6 | −0.4 (− 0.9, − 0.1) | 14.7 | 0.035 | 0.148 |
| 16 | Ankle PF U | 0.59 (0.27) | 0.61 (0.27) | 0.73 (0.26) | 0.71 (0.27) | −0.6 | −0.4 (− 0.9, 0.1) | 15.2 | 0.0379 | 0.185 |
| 17 | Hip FLX U | 1.19 (0.30) | 1.19 (0.35) | 1.30 (1.30) | 1.30 (0.35) | −0.3 | −0.3 (− 0.8, 0.2) | 8.8 | 0.2043 | 0.105 |
| 18 | Hip ER U | 0.29 (0.11) | 0.30 (0.12) | 0.34 (0.13) | 0.33 (0.12) | −0.5 | −0.3 (− 0.8, 0.2) | 9.5 | 0.0671 | 0.288 |
| 19 | Hip AB I | 0.90 (0.35) | 0.91 (0.34) | 1.01 (0.29) | 1.00 (0.34) | −0.4 | −0.3 (− 0.8, 0.2) | 9.4 | 0.19092 | 0.148 |
| 20 | Ankle EV U | 0.23 (0.08) | 0.24 (0.09) | 0.26 (0.08) | 0.26 (0.08) | −0.5 | −0.2 (− 0.8, 0.3) | 8.0 | 0.0911 | 0.375 |
| 21 | Hip EXT U | 1.31 (0.51) | 1.34 (0.54) | 1.50 (0.51) | 1.47 (0.54) | −0.4 | −0.2 (− 0.8, 0.3) | 9.3 | 0.1499 | 0.146 |
| 22 | Knee FLX U | 0.74 (0.38) | 0.77 (0.39) | 0.90 (0.37) | 0.87 (0.39) | −0.4 | −0.2 (− 0.7, 0.3) | 12.2 | 0.1042 | 0.390 |
| 23 | Ankle INV U | 0.25 (0.09) | 0.26 (0.08) | 0.28 (0.07) | 0.27 (0.08) | −0.3 | −0.2 (− 0.7, 0.3) | 3.8 | 0.2252 | 0.534 |
| 24 | Hip IR U | 0.80 (0.24) | 0.82 (0.24) | 0.87 (0.21) | 0.85 (0.24) | −0.3 | −0.1 (− 0.7, 0.4) | 3.6 | 0.2768 | 0.588 |
Notes. Statistically significant differences are in bold type. KOA Patients in the knee osteoarthritis group, HC Healthy control group, Rn Rank-position for the joint-and-torque-direction on muscle weakness (i.e., SMD) in the KOA-group compared to the HC-group, * = significant different, † = highly significant (two-tailed ANCOVA); Unadj Unadjusted, Adj Adjusted for the covariate age, I the (most) involved leg (in KOA-group) or non-dominant leg (in HC-group), U Uninvolved leg or dominant leg (if HC-group), dir. = direction, EV Eversion, ER External rotation, IR Internal rotation, INV Inversion, DF Dorsal flexion, EXT Extension, FLX Flexion, PF Plantar flexion, ER External rotation, M Mean, SD Standard deviation, CI Confidence interval (lower limit, upper limit), SMD Standardized mean difference or Cohen’s d, p P-value. All strength measures are peak strength regardless of range of motion, except for the knee joint (peak strength at 30° flexion) and hip AB or AD (peak strength in the anatomical position). Results are normalized for body mass (i.e., M and SD are given as Nm/kg)