Table 1.
Biomechanical Factors Obtained From Principal Components Analysis
| Factor |
Factor Loadingsa |
Biomechanical Changes on Jump Landing as Factor Score Increasesb |
Functional Result |
| 1 | ↑ Peak hip flexion (0.180), flexion excursion (0.270), hip work absorption (0.431) | ↑ Hip flexion, energy absorption | ↑ Dissipation of landing forces at hip |
| 2 | ↑ Initial hip flexion (0.188), flexion moment (0.219), stiffness (0.347) | Ground contact in ↑ hip flexion; ↑ hip-flexion moment, stiffness | ↑ Loads on hip |
| 3 | ↑ Peak ankle flexion (0.332), peak knee flexion (0.235), knee-flexion excursion (0.288), knee work absorption (0.220) | ↑ Knee, ankle flexion at peak landing; ↑ knee energy absorption | ↑ Dissipation of landing forces at knee |
| 4 | ↑ Ground reaction force (0.256), anterior knee shear forces (0.343), knee-extensor moment (0.432), stiffness (0.386), work absorption (0.232) | ↑ Stiff knee on landing → ↑ knee-extensor loads, shear forces, ground reaction forces | ↑ Loads on knee |
| 5 | ↑ Initial ankle flexion (0.433); ↓ ankle-flexion excursion (−0.393) | Ground contact in ↑ ankle dorsiflexion; ↓ dorsiflexion motion on landing | ↓ Reliance on ankle motion to dissipate landing forces |
| 6 | ↑ Anterior knee shear forces (0.222), ankle-extensor moment (0.323), stiffness (0.289), work absorption (0.253) | ↑ Stiff ankle on landing → ↑ ankle plantar-flexor loads; ↑ anterior knee shear forces | ↑ Loads on ankle plantar-flexor loads, structures that restrain anterior tibial translation |
| 7 | ↑ Initial hip external rotation (0.264), initial knee (0.216) and peak knee valgus (0.213), initial knee internal rotation (−0.346); ↓ peak knee external rotation (−0.330) and knee internal-rotation excursion (0.282) | Ground contact in ↑ relative hip external rotation, knee valgus, internal rotation; remain in ↑ knee valgus, internal rotation | Knee posture associated with ↑ anterior cruciate ligament loading, injury risk during landing |
| 8 | ↑ Hip-adduction excursion (−0.183), knee-valgus excursion (0.208); ↓ peak hip internal rotation (0.260), internal-rotation excursion (0.264), peak knee varus (0.236), knee-varus excursion (0.324) | ↑ Frontal-plane hip adduction, knee-valgus motion; ↓ hip internal-rotation motion | More functional valgus posture during landing |
| 9 | ↑ Peak knee internal rotation (–.299), internal-rotation excursion (−0.229) | ↑ Knee internal-rotation motion during landing | |
| 10 | ↑ Knee external-rotation excursion (0.694) | ↑ Knee external-rotation motion during landing | |
| 11 | ↓ Hip-adduction moment (0.315), hip external-rotation moment (−0.225), knee-varus moment (0.411), knee internal-rotation moment (0.251) | ↓ Hip adduction and external rotation, knee-varus and internal-rotation moments during landing | ↓ Peak loading of structures associated with transverse, frontal control of hip, knee |
a
Anterior-posterior flexion angles, extensor moments, stiffness, and work-absorption values are positive.
b
If factor score decreases, the opposite biomechanical changes are observed.