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MINERVA ORTOPEDICA E TRAUMATOLOGICA
A Journal on Orthopedics and Traumatology
Minerva Ortopedica e Traumatologica 2009 June;60(3):193-204
Drop and hop jump GRFs and joint kinematics of braced non-injured subjects: preliminary study
Rishiraj N., Taunton J. E., Lloyd-Smith R., Niven B., Regan W., Woollard R.
1 University of Otago, Otago, New Zealand
2 ACTIN Health and Rehabilitation Inc. Vancouver, BA, Canada
3 School of Human Kinetics University of British Columbia Vancouver, BA, Canada
4 Allan McGavin Sports Medicine Centre (Primary Care) University of British Columbia Vancouver, BA, Canada
5 Allan McGavin Sports Medicine Centre (Primary Care) University of British Columbia Athletics Vancouver, BA, Canada
6 Centre for Application of Statistics and Mathematics Department of Mathematics and Statistics University of Otago, Otago, New Zealand
7 Allan McGavin Sports Medicine Centre (Orthopedics)University of British Columbia Vancouver, BA, Canada
8 Department of Family Practice University of British Columbia Vancouver, BA, Canada
Aim. The objective of this study was to determine if functional knee brace (FKB) use by non-injured athletes altered peak vertical ground reaction forces (PVGRF) during the drop- and hop-jump. Furthermore, the authors aimed to study if PVGRF was changed, what role, if any, the knee and ankle joint angles contributed to changes in the PVGRF at landing. Also, with continued FKB use, in 24 trials over three days, it was evaluated if familiarisation to FKB use led to lower PVGRF during the two jumping.
Methods. This study had a 2¥3 non-braced (NBr) and braced repeated factorial design. Five healthy athletes (aged 19-23 years) completed all testing. Subjects performed hop- and drop-jump tests and completed three practice and eight data collection trials per test, over six days (three days NBr and three days braced). PVGRF and kinematic (knee and ankle joint) data were recorded each testing day to determine if landing strategies changed while using a FKB and if accommodation to FKB use was possible.
Results. During both jump tasks lower group mean PVGRF were generated while using a FKB; the hop-jump data were statistically significant (F1,4=9.64, P=0.036). The lower PVGRF, during both tasks, were generated with the knee joint in greater extension and the ankle joint in greater dorsiflexion. Furthermore, an accommodation trend was noted as PVGRF percent performance difference decreased with continued FKB use.
Conclusion. The absorption of PVGRF by the dorsiflexed ankle joint and/or the FKB may keep traumatic forces from reaching the anterior cruciate ligament, especially during the hop-jump. This preliminary study may be used in the future to explain the perceived differences between PVGRF and joint kinematics of healthy braced athletes.