Elsevier

Clinical Biomechanics

Volume 22, Issue 6, July 2007, Pages 674-680
Clinical Biomechanics

Leg kinematics and kinetics in landing from a single-leg hop for distance. A comparison between dominant and non-dominant leg

https://doi.org/10.1016/j.clinbiomech.2007.02.007Get rights and content

Abstract

Background

Anterior cruciate ligament (ACL) deficiency can be a major problem for athletes and subsequent reconstruction of the ACL may be indicated if a conservative regimen has failed. After ACL reconstruction signs of abnormality in the use of the leg remain for a long time. It is expected that the landing after a single-leg hop for distance (horizontal hop) might give insight in the differences in kinematics and kinetics between uninjured legs and ACL-reconstructed legs. Before the ACL-reconstructed leg can be compared with the contralateral leg, knowledge of differences between legs of uninjured subjects is needed.

Methods

Kinematic and kinetic variables of both legs were measured with an optoelectronic system and a force plate and calculated by inverse dynamics. The dominant leg (the leg with biggest horizontal hop distance) and the contralateral leg of nine uninjured subjects were compared.

Findings

No significant differences were found in most of the kinematic and kinetic variables between dominant leg and contralateral leg of uninjured subjects. Only hop distance and hip extension angles differed significantly.

Interpretation

This study suggests that there are no important differences between dominant leg and contralateral leg in healthy subjects. As a consequence, the uninvolved leg of ACL-reconstructed patients can be used as a reference. The observed variables of this study can be used as a reference of normal values and normal differences between legs in healthy subjects.

Introduction

Athletes with a high activity level who sustain an anterior cruciate ligament (ACL) rupture may need a reconstruction of their ACL if a course of conservative rehabilitation has failed. ACL reconstruction is the treatment of choice to achieve a return back on pre-injury activity level (Deehan and Pinczewski, 2002, Fitzgerald et al., 2000, Shelton et al., 1997, Ciccotti et al., 1994, Andersson, 1993). Despite improvements in surgical techniques and subsequent rehabilitation, abnormal motor control persists during functional activities (Shelbourne and Nitz, 1990). Abnormalities of the knee in walking up to six months after ACL reconstruction have been reported (Gokeler et al., 2003). Even less is known about the biomechanical characteristics during more demanding activities.

In most kinetic and kinematic studies about ACL-reconstructed subjects the involved leg and the uninvolved leg are compared. A possible confounder is that differences in involved and uninvolved leg, present before the ACL problems, are not taken in account. In general both legs are not equal. The question in this study therefore is: can the uninvolved leg be used as reference regardless whether it was the dominant leg before the ACL-rupture or not? In the present study differences between dominant leg and contralateral leg in kinematics and kinetics will be studied of healthy subjects. The single-leg hop for distance is used as the movement for analysis. This movement is comparable with the high functional demands that are needed in sport. It is already used as a functional test for lower extremity and has turned out to be a reliable measure (Bolgla and Keskula, 1997, Ross et al., 2002). Wilk et al. (1994) used this measure specifically for ACL-reconstructed patients and found a moderate positive correlation between isokinetic peak torque and subjective knee scores with this hop test.

The expectation is that this horizontal hop will be useful in detecting changes in knee biomechanics. Sagittal kinematics and kinetics of the two legs of healthy subjects will be studied during landing. Landing is chosen because this stresses the knee most. Furthermore, data analysis of Juris et al. (1997) suggests that force absorption is more critical than force production to evaluate functional capacity of reconstructed ACL knees. With information of the sagittal kinematics and kinetics more insight in differences of dominant leg and contralateral leg in these determinants will be obtained. Kinematics variables that will be used are hop distance, hop height, peak flexion angles, peak extension angles and maximal excursion angles. Kinetics variables that will be studied are vertical and horizontal GRF (ground reaction force), extension moments and support moment.

The hypothesis is that there will only be small differences between the dominant leg and contralateral leg in the healthy subjects because there is no reason for different motor strategies during landing between limbs. A study of Ernst et al. (2000) supports this hypothesis because they did not find differences in kinetic variables with vertical jump and lateral step-up movements in healthy subjects. For the horizontal hop distance we expect to find a symmetry index above the 85% which Noyes et al. (1991) used as the limit for normal symmetry (Barber et al., 1990, Noyes et al., 1991). It is important for further research to know the magnitude of the differences between dominant leg and contralateral leg. When this is known, comparison between injured leg and contralateral leg in patients can be done with more confidence.

Section snippets

Subjects

Six healthy males and three females participated in the measurements. Mean age was 26.7 (5.9), with a mass of 79.24 (10.50) kg and a leg length of 100 (5.7) cm. (mean (SD)) The subjects had no injuries on the leg and back for at least three months, had no previous surgery on the leg, no history of neurological disease, no vestibular or visual disturbance. All the subjects were active in a sport in which leg movement is important, like soccer, baseball, korfball and Judo. The study was approved by

Horizontal hop distance

The mean horizontal hop index was 95.5 (2.1) Mean distance of the dominant leg was 143.0 (6.8) cm compared to the contralateral leg: 136.8 (5.7) cm. This is a significant difference (P < 0.01).

Hop height

For the dominant leg a mean hop height of 12.2 (3.5) cm, within subjects SD 2.6 cm, was reached in a horizontal hop and for the contralateral leg this was 12.7 (2.3) cm, within subjects SD was 2.2 cm. This difference between legs was not significant. The mean index for hop height was 1.08 (0.18).

Joint angles

There was a

Discussion

In the present study, we have defined the dominant leg as the leg with which the largest horizontal hop distance was reached. This has to be distinguished from the preferred leg. The preferred leg is the leg that is used to manipulate an object. A review of Peters (1988) showed already that in high jumps most athletes preferred the left leg while in the long jump it was equally divided. In this study 3 of 9 subjects had the biggest hop distance with their left leg.

The high hop index (mean

Conclusion

The question in this study was: can the uninvolved leg be used as reference regardless whether it was the dominant leg before the ACL-rupture or not? Only hop distance and hip extension angles differed significantly. This study suggests that there are no important differences between dominant leg and contralateral leg in healthy subjects. As a consequence, the uninvolved leg of ACL-reconstructed patients can be used as a reference. The observed variables of this study can be used as reference

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