Introduction
Materials and methods
Subject sample, study design and data collection
Test procedures
Side-cutting manoeuvre
3D biomechanical measurements
EMG: assessment of neuromuscular activity
Maximal isometric muscle strength
Injury registration
Statistical analysis
Per 0.1 units increase | Per 1 unit increase | Per 10 units increase | |
---|---|---|---|
Kinematics | |||
Knee flexion angle at IC (°) | X | ||
Hip flexion angle at IC (°) | X | ||
Knee adduction angle at IC (°) | X | ||
Knee internal rotation angle at IC (°) | X | ||
Kinetics | |||
Knee flexion moment (Nm/kg BW) | X | ||
Hip flexion moment (Nm/kg BW) | X | ||
Knee adduction moment (Nm/kg BW) | X | ||
Hip internal rotation moment (Nm/kg BW) | X | ||
Isometric muscle strength | |||
Knee flexion MVC (N/kg BW) | X | ||
Hip extension MVC (N/kg BW) | X | ||
Hip abduction MVC (N/kg BW) | X | ||
Hip external rotation MVC (N/kg BW) | X | ||
EMG pre-activity | |||
Vastus lateralis (% of max EMG) | X | ||
Vastus medialis (% of max EMG) | X | ||
Biceps femoris (% of max EMG) | X | ||
Semitendinosus (% of max EMG) | X |
Results
Study flow and participant characteristics
Overall (n = 90) | Uninjured (n = 81) | ACL injured (n = 9) | |
---|---|---|---|
Demographics | |||
Age, years | 16.9 (1.2) | 16.9 (1.2) | 16.7 (1.3) |
Height, cm | 172 (7) | 172 (7) | 176 (5) |
Weight, kg | 66 (8) | 66 (8) | 69 (8) |
Body mass index (kg/m2) | 22 (2) | 22 (2) | 22 (2) |
Sport (handball:football) | 54:36 | 48:33 | 6:3 |
Experience (years) | 10 (2) | 10 (2) | 9 (2) |
Kinematics | |||
Knee flexion angle at IC (°) | 25 (8) | 26 (8) | 21 (9) |
Hip flexion angle at IC (°) | 47 (10) | 48 (10) | 43 (6) |
Knee adduction angle at IC (°) | 1 (3) | 1 (3) | 1 (3) |
Knee internal rotation angle at IC (°) | − 3 (6) | − 3 (5) | 4 (10) |
Kinetics | |||
Knee flexion moment (Nm/kg BW) | 3.1 (0.5) | 3.1 (0.5) | 3.1 (0.5) |
Hip flexion moment (Nm/kg BW) | 3.8 (1.1) | 3.8 (1.1) | 3.9 (1.3) |
Knee adduction moment (Nm/kg BW) | − 0.7 (0.5) | − 0.7 (0.4) | − 1.0 (0.7) |
Hip internal rotation moment (Nm/kg BW) | 0.3 (0.2) | 0.3 (0.2) | 0.4 (0.2) |
Isometric muscle strength | |||
Knee flexion MVC (N/kg BW) | 4.0 (0.6) | 4.0 (0.6) | 4.0 (0.6) |
Hip extension MVC (N/kg BW) | 3.7 (0.5) | 3.7 (0.6) | 3.8 (0.4) |
Hip abduction MVC (N/kg BW) | 2.6 (0.4) | 2.6 (0.4) | 2.4 (0.3) |
Hip external rotation MVC (N/kg BW) | 2.2 (0.3) | 2.3 (0.3) | 2.0 (0.1) |
EMG pre-activity | |||
Vastus lateralis (% of max EMG) | 33 (21) | 34 (21) | 27 (16) |
Vastus medialis (% of max EMG) | 38 (24) | 39 (24) | 28 (17) |
Biceps femoris (% of max EMG) | 32 (17) | 33 (17) | 24 (16) |
Semitendinosus (% of max EMG) | 46 (22) | 48 (23) | 32 (11) |
Overall injury incidence
RR (95% CI) | ||||
---|---|---|---|---|
Unadjusted | P value | Adjusted for sport | P value | |
Knee flexion angle at IC (°)§ | 0.47 (0.16–1.35) | 0.159 | 0.43 (0.13–1.45) | n.s. |
Hip flexion angle at IC (°)§ | 0.61 (0.39–0.99) | 0.032 | 0.56 (0.34–0.92) | 0.021 |
Knee adduction angle at IC (°)# | 0.97 (0.76–1.23) | 0.804 | 0.97 (0.77–1.24) | n.s. |
Knee internal rotation angle at IC (°)# | 1.12 (1.07–1.18) | < 0.001 | 1.13 (1.08–1.19) | < 0.001 |
Knee flexion moment (Nm/kg BW)* | 1.01 (0.90–1.13) | 0.878 | 1.00 (0.89–1.14) | n.s. |
Hip flexion moment (Nm/kg BW)* | 1.01 (0.96–1.07) | 0.652 | 1.01 (0.96–1.07) | n.s. |
Knee adduction moment (Nm/kg BW)* | 0.90 (0.81–1.00) | 0.050 | 0.90 (0.80–1.00) | n.s. |
Hip internal rotation moment (Nm/kg BW)* | 1.14 (0.77–1.69) | 0.509 | 1.15 (0.77–1.73) | n.s. |
Knee flexion MVC (N/kg BW)* | 1.00 (0.89–1.12) | 0.928 | 1.00 (0.88–1.13) | n.s. |
Hip extension MVC (N/kg BW)* | 1.03 (0.94–1.12) | 0.558 | 1.04 (0.93–1.15) | n.s. |
Hip abduction MVC (N/kg BW)* | 0.89 (0.76–1.05) | 0.161 | 0.89 (0.75–1.06) | n.s. |
Hip external rotation MVC (N/kg BW)* | 0.77 (0.68–0.89) | < 0.0001 | 0.77 (0.66–0.89) | 0.001 |
Vastus lateralis (% of max EMG)§ | 0.84 (0.60–1.19) | 0.332 | 0.85 (0.63–1.16) | n.s. |
Vastus medialis (% of max EMG)§ | 0.79 (0.57–1.09) | 0.149 | 0.79 (0.56–1.11) | n.s. |
Biceps femoris (% of max EMG)§ | 0.68 (0.37–1.23) | 0.196 | 0.67 (0.36–1.23) | n.s. |
Semitendinosus (% of max EMG)§ | 0.65 (0.50–0.86) | 0.002 | 0.62 (0.43–0.89) | 0.010 |