Introduction
Materials and methods
Participants
Procedure
Definition of return to physical activity
Muscle function
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Two reliable and valid isotonic tests for muscular strength, to reflect quadriceps and hamstring muscular power in knee extension and knee flexion [28]. The strength tests were performed in a knee extension and knee flexion weight training machine (Precor, Competition Line, Borås, Sweden). The average power was recorded through a linear encoder and calculated by Muscle Lab, a computerised muscle function measuring system (Ergotest Technology, Oslo, Norway). Tests were performed between 0º and 110° of knee flexion.
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Three reliable and valid single-leg tests for hop performance [14]: the vertical jump, the hop for distance and the side hop.
Patient-reported outcome measures (PROMs)
Statistical analyses
Results
Return to pre-injury Tegner
Demographics | Women | Men | ||||
---|---|---|---|---|---|---|
Returned (n = 23) | Not returned (n = 54) |
p value | Returned (n = 29) | Not returned (n = 51) |
p value | |
Months after surgery | 9.9 ± 2.6 | 10.0 ± 3.5 | n.s. | 9.9 ± 3.3 | 10.6 ± 3.4 | n.s. |
Age | ||||||
Mean ± SD | 20.8 ± 3.0 | 21.4 ± 3.8 | n.s. | 23.7 ± 4.5 | 23.3 ± 4.2 | n.s. |
Height | ||||||
Mean ± SD | 172 ± 5.8 | 168 ± 5.3 | 0.004* | 181 ± 7.6 | 181 ± 5.2 | n.s. |
Weight | ||||||
Mean ± SD | 67 ± 8.1 | 62 ± 13.1 | n.s. | 77 ± 10.5 | 80 ± 9.2 | n.s. |
Pre-injury Tegner | ||||||
Median [range] | 8 [6–10] | 8 [6–10] | n.s. | 9 [6–10] | 9 [6–10] | n.s. |
Mean ± SD | 7.9 ± 2.3 | 8.2 ± 1.4 | 8.1 ± 1.9 | 8.8 ± 1.0 | ||
Pre-injury PAS | ||||||
Median [range] | 4 [3–4] | 4 [2–4] | n.s. | 4 [2–4] | 4 [2–4] | n.s. |
Mean ± SD | 3.7 ± 0.5 | 3.6 ± 0.5 | 3.7 ± 0.5 | 3.8 ± 0.9 | ||
Knee extension (n) | 21 | 53 | 29 | 50 | ||
Knee flexion (n) | 21 | 53 | 29 | 49 | ||
Vertical jump (n) | 7 | 12 | 8 | 17 | ||
Hop for distance (n) | 14 | 25 | 18 | 23 | ||
Side hop (n) | 14 | 24 | 19 | 22 | ||
KOOS (n) | 23 | 54 | 27 | 51 |
PROM Mean ± SD Median [range] | Women | Men | ||||
---|---|---|---|---|---|---|
Returned (n = 23) | Not returned (n = 54) |
p value | Returned (n = 29) | Not returned (n = 51) |
p value | |
Tegner present | 7.4 ± 2.3 | 4.4 ± 1.5 | <0.001* | 7.6 ± 1.9 | 5.1 ± 1.5 | <0.001* |
8 [2–10] | 4 [2–7] | 8 [4–10] | 4 [1–7] | |||
Tegner goal | 8.1 ± 2.3 | 7.4 ± 2.4 | n.s. | 8.2 ± 2.5 | 8.8 ± 1.1 | n.s. |
8 [2–10] | 8 [5–10] | 9 [4–10] | 8 [5–10] | |||
PAS present | 3.2 ± 1.1 | 2.7 ± 0.6 | <0.001* | 3.6 ± 1.3 | 2.6 ± 0.8 | <0.001* |
3 [2–4] | 3 [1–4] | 3 [2–4] | 3 [1–4] | |||
PAS goal | 3.5 ± 1.1 | 3.3 ± 1.3 | n.s. | 3.8 ± 1.4 | 3.8 ± 0.4 | n.s. |
4 [2–4] | 4 [2–4] | 4 [3, 4] | 4 [2–4] | |||
K-SES present | 6.9 ± 1.4 | 6.1 ± 1.4 | 0.005* | 7.3 ± 0.8 | 6.5 ± 1.0 | <0.001* |
9 [2–10] | 8 [3–10] | 9 [7–10] | 7 [1–10] | |||
K-SES future | 7.8 ± 1.9 | 6.8 ± 2.7 | n.s. | 8.0 ± 1.4 | 7.0 ± 1.9 | 0.026* |
9 [1–10] | 8 [2–10] | 8 [4–10] | 7 [2–10] | |||
KOOS pain | 80 ± 15 | 73 ± 16 | <0.001* | 77 ± 19 | 69 ± 14 | <0.001* |
82 [43–100] | 71 [36–100] | 82 [32–100] | 68 [43–100] | |||
KOOS symptoms | 91 ± 13 | 86 ± 11 | <0.001* | 89 ± 11 | 84 ± 12 | <0.001* |
92 [33–100] | 89 [61–100] | 94 [53–100] | 86 [36–100] | |||
KOOS ADL | 97 ± 10 | 94 ± 7 | <0.001* | 96 ± 9 | 94 ± 8 | <0.001* |
100 [47–100] | 97 [74–100] | 99 [56–100] | 97 [68–100] | |||
KOOS sport | 80 ± 20 | 68 ± 22 | <0.001* | 83 ± 17 | 66 ± 21 | <0.001* |
85 [10–100] | 70 [15–100] | 87 [50–100] | 70 [10–100] | |||
KOOS QoL | 68 ± 17 | 55 ± 18 | <0.001* | 72 ± 16 | 53 ± 20 | <0.001* |
63 [13–94] | 50 [19–100] | 67 [50–100] | 56 [13–100] |
Test of muscle function Mean ± SD | Women | Men | ||||
---|---|---|---|---|---|---|
Returned | Not returned |
p value | Returned | Not returned |
p value | |
Knee extension IL (W/kg) | 3.2 ± 1.0 | 2.6 ± 0.7 | 0.010* | 4.1 ± 0.6 | 3.9 ± 1.0 | n.s. |
Knee extension NL (W/kg) | 3.5 ± 0.9 | 2.9 ± 0.9 | 0.014* | 4.4 ± 0.6 | 4.4 ± 0.9 | n.s. |
Knee flexion IL (W/kg) | 1.9 ± 0.5 | 1.6 ± 0.4 | n.s. | 2.5 ± 0.5 | 2.4 ± 0.6 | n.s. |
Knee flexion NL (W/kg) | 2.1 ± 0.5 | 1.8 ± 0.5 | n.s. | 2.9 ± 0.5 | 2.8 ± 0.4 | n.s. |
Vertical jump IL (cm/kg) | 0.23 ± 0.04 | 0.21 ± 0.06 | n.s. | 0.26 ± 0.07 | 0.27 ± 0.07 | n.s. |
Vertical jump NL (cm/kg) | 0.26 ± 0.04 | 0.27 ± 0.03 | n.s. | 0.29 ± 0.05 | 0.27 ± 0.06 | n.s. |
Hop for distance IL (cm/kg) | 2.1 ± 0.4 | 1.9 ± 0.3 | n.s. | 2.0 ± 0.3 | 2.0 ± 0.3 | n.s. |
Hop for distance NL (cm/kg) | 2.1 ± 0.3 | 2.0 ± 0.3 | n.s. | 2.1 ± 0.4 | 2.1 ± 0.4 | n.s. |
Side hop IL (n/kg) | 0.7 ± 0.2 | 0.5 ± 0.2 | 0.012* | 0.8 ± 0.1 | 0.7 ± 0.2 | n.s. |
Side hop NL (n/kg) | 0.8 ± 0.2 | 0.6 ± 0.2 | 0.004* | 0.8 ± 0.1 | 0.7 ± 0.1 | n.s. |
Return to Tegner 6 or higher
Demographics | Women | Men | ||||
---|---|---|---|---|---|---|
Returned (n = 36) | Not returned (n = 41) |
p value | Returned (n = 49) | Not returned (n = 31) |
p value | |
Months after surgery | ||||||
Mean ± SD | 10.2 ± 3.1 | 9.8 ± 3.4 | n.s. | 10.1 ± 3.1 | 10.8 ± 3.7 | n.s. |
Age | ||||||
Mean ± SD | 21.6 ± 3.9 | 21.0 ± 3.2 | n.s. | 23.2 ± 4.0 | 23.8 ± 4.8 | n.s. |
Height | ||||||
Mean ± SD | 170.9 ± 5.9 | 167.0 ± 5.1 | 0.007* | 180.3 ± 5.8 | 183.1 ± 6.3 | n.s. |
Weight | ||||||
Mean ± SD | 67.6 ± 8.4 | 61.0 ± 14.0 | 0.014* | 77.6 ± 8.8 | 81.5 ± 10.9 | n.s. |
Pre-injury Tegner | ||||||
Median [range] | 8 [6–10] | 8 [6–10] | n.s. | 9 [6–10] | 8 [6–10] | n.s. |
Mean ± SD | 8.5 ± 1.1 | 8.0 ± 1.5 | 8.9 ± 1.0 | 8.1 ± 1.8 | ||
Pre-injury PAS | ||||||
Median [range] | 4 [3–4] | 4 [2–4] | n.s. | 4 [2–4] | 4 [2–4] | n.s. |
Mean ± SD | 3.7 ± 0.5 | 3.7 ± 0.5 | 3.8 ± 0.4 | 3.7 ± 0.8 | ||
Knee extension (n) | 34 | 39 | 49 | 30 | ||
Knee flexion (n) | 34 | 39 | 49 | 29 | ||
Vertical jump (n) | 11 | 8 | 17 | 8 | ||
Hop for distance (n) | 20 | 19 | 29 | 12 | ||
Side hop (n) | 20 | 18 | 29 | 12 | ||
KOOS (n) | 35 | 41 | 47 | 31 |
PROM Mean ± SD Median [range] | Women | Men | ||||
---|---|---|---|---|---|---|
Returned (n = 36) | Not returned (n = 41) |
p value | Returned (n = 49) | Not returned (n = 31) |
p value | |
Tegner present | 7.3 ± 1.3 | 3.8 ± 1.0 | <0.001* | 7.4 ± 1.3 | 3.9 ± 0.9 | <0.001* |
7 [6–10] | 3 [2–5] | 7 [6–10] | 4 [1–5] | |||
Tegner goal | 8.3 ± 1.9 | 7.2 ± 2.3 | 0.001* | 8.9 ± 1.7 | 8.0 ± 1.7 | 0.006* |
8 [6–10] | 7 [4–10] | 9 [7–10] | 7 [3–10] | |||
PAS present | 3.2 ± 0.6 | 2.6 ± 0.6 | <0.001* | 3.1 ± 0.9 | 2.7 ± 1.4 | 0.002* |
3 [2–4] | 2 [1–4] | 3 [2–4] | 2 [1–4] | |||
PAS goal | 3.6 ± 0.9 | 3.3 ± 1.2 | n.s. | 3.8 ± 0.8 | 3.8 ± 1.1 | n.s. |
4 [3, 4] | 3 [3, 4] | 4 [3, 4] | 3 [2–4] | |||
K-SES present | 7.0 ± 1.3 | 5.8 ± 1.3 | <0.001* | 6.9 ± 1.0 | 6.5 ± 1.0 | n.s. |
9 [2–10] | 6 [3–10] | 8 [6–10] | 7 [1–10] | |||
K-SES future | 7.8 ± 2.3 | 6.5 ± 2.6 | 0.008* | 7.8 ± 1.7 | 6.9 ± 2.0 | 0.048* |
8 [3–10] | 6 [1–10] | 8 [4–10] | 6 [2–10] | |||
KOOS pain | 75 ± 18 | 74 ± 14 | 0.030* | 76 ± 17 | 70 ± 14 | <0.001* |
79 [36–100] | 71 [39–100] | 79 [32–100] | 68 [43–93] | |||
KOOS symptoms | 91 ± 12 | 84 ± 11 | <0.001* | 88 ± 10 | 83 ± 13 | <0.001* |
94 [33–100] | 89 [61–100] | 89 [53–100] | 86 [36–100] | |||
KOOS ADL | 97 ± 9 | 93 ± 7 | <0.001* | 96 ± 8 | 92 ± 9 | <0.001* |
100 [47–100] | 94 [74–100] | 99 [56–100] | 97 [68–100] | |||
KOOS sport | 81 ± 18 | 62 ± 22 | <0.001* | 81 ± 15 | 62 ± 22 | <0.001* |
85 [10–100] | 60 [15–100] | 85 [50–100] | 70 [10–100] | |||
KOOS QoL | 65 ± 19 | 52 ± 17 | 0.021* | 68 ± 16 | 49 ± 19 | <0.001* |
63 [13–100] | 50 [19–81] | 67 [38–100] | 50 [13–88] |
Test of muscle function Mean ± SD | Women | Men | ||||
---|---|---|---|---|---|---|
Returned | Not returned |
p value | Returned | Not returned |
p value | |
Knee extension IL (W/kg) | 3.0 ± 0.9 | 2.6 ± 0.7 | 0.032* | 4.1 ± 0.8 | 3.8 ± 1.0 | n.s. |
Knee extension NL (W/kg) | 3.3 ± 0.8 | 2.8 ± 0.6 | 0.024* | 4.4 ± 0.7 | 4.3 ± 1.0 | n.s. |
Knee flexion IL (W/kg) | 1.8 ± 0.5 | 1.6 ± 0.4 | n.s. | 2.5 ± 0.4 | 2.2 ± 0.7 | 0.039* |
Knee flexion NL (W/kg) | 2.1 ± 0.4 | 1.7 ± 0.5 | 0.017* | 2.9 ± 0.4 | 2.8 ± 0.5 | n.s. |
Vertical jump IL (cm/kg) | 0.22 ± 0.04 | 0.21 ± 0.07 | n.s. | 0.26 ± 0.06 | 0.28 ± 0.08 | n.s. |
Vertical jump NL (cm/kg) | 0.26 ± 0.04 | 0.28 ± 0.01 | n.s. | 0.27 ± 0.06 | 0.29 ± 0.06 | n.s. |
Hop for distance IL (cm/kg) | 2.0 ± 0.4 | 1.9 ± 0.3 | n.s. | 2.0 ± 0.3 | 2.1 ± 0.3 | n.s. |
Hop for distance NL (cm/kg) | 2.1 ± 0.3 | 2.0 ± 0.3 | n.s. | 2.1 ± 0.3 | 2.1 ± 0.4 | n.s. |
Side hop IL (n/kg) | 0.7 ± 0.2 | 0.6 ± 0.2 | n.s. | 0.8 ± 0.2 | 0.7 ± 0.2 | n.s. |
Side hop NL (n/kg) | 0.7 ± 0.2 | 0.6 ± 0.2 | n.s. | 0.8 ± 0.1 | 0.8 ± 0.1 | n.s. |