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1st Joint ESMAC-GCMAS Meeting - Análise de Marcha

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O-57<br />

DYNAMIC FUNCTION AFTER ANTERIOR CRUCIATE LIGAMENT<br />

RECONSTRUCTION IS RELATED TO GRAFT CHOICE<br />

Webster Kate Dr, Feller Julian Assoc. Prof., Joanne Wittwer Ms.<br />

Musculoskeletal Research Centre and Gait CCRE, La Trobe University, Melbourne Australia<br />

Summary/Conclusions<br />

In this study clear differences were observed in the knee kinematic and kinetic profiles between<br />

patients who had un<strong>de</strong>rgone hamstring or patellar tendon anterior cruciate ligament (ACL)<br />

reconstruction. Patients with patellar tendon grafts <strong>de</strong>monstrated reduced external knee flexion<br />

moments whereas patients with hamstring grafts <strong>de</strong>monstrated reduced external knee extension<br />

moments. These results suggest that there are graft-specific differences in knee biomechanics<br />

after ACL reconstruction that appear to relate to the donor site.<br />

Introduction<br />

ACL reconstruction is a common procedure. However, <strong>de</strong>bate continues as to whether the<br />

patellar tendon (PT) or the hamstring tendon (HS) graft is preferable. A number of studies have<br />

examined the effect of ACL reconstruction on joint kinematic and kinetic patterns during gait.<br />

These have shown that although there is a ten<strong>de</strong>ncy towards gait normalization after the<br />

reconstructive procedure, altered moments about the knee in the flexion-extension axis still<br />

persist [1-4]. It has been suggested that abnormal gait pattens might have implications for the<br />

long term <strong>de</strong>velopment of pathologic knee conditions [4, 5]. However, in the majority of these<br />

studies, only patients who had received a PT graft were examined. Therefore, the purpose of this<br />

study was to investigate biomechanical differences associated with the use of both HS and PT<br />

grafts during walking and also during higher impact activities that involved single limb landing.<br />

Statement of Clinical Significance<br />

As both hamstring and patellar tendon grafts are used for ACL reconstruction, it is clinically<br />

relevant to un<strong>de</strong>rstand the biomechanical differences in knee function associated with each graft.<br />

The reduced knee flexion angles and moments we observed in the patellar tendon patients may<br />

place this group at greater risk of <strong>de</strong>veloping <strong>de</strong>generative joint changes.<br />

Methods<br />

Two experiments were conducted. In experiment 1, the gait patterns of 17 PT patients, 17 HS<br />

patients and 17 controls matched for activity were compared. In experiment 2, single-limb<br />

landing patterns for vertical and horizontal hops were compared between 17 PT patients, 17 HS<br />

and 12 control subjects. ACL patients were tested 9 to 12 months following surgery. For both<br />

experiments a 3-dimensional motion analysis and force plate system was used to <strong>de</strong>termine<br />

sagittal plane kinematics and kinetics of the lower limb.<br />

Results<br />

In experiment 1 (walking) there were significant differences in the moments about the operated<br />

knee that related to graft type. The PT patients had a reduced external knee flexion moment at<br />

mid stance whilst the HS patients had a reduced external extension moment at terminal stance.<br />

Experiment 2 (landing) results for both the horizontal and vertical hops also showed a reduction<br />

in the external flexion moment about the operated knee for the PT group compared to the nonoperated<br />

si<strong>de</strong>, the control subjects and the operated si<strong>de</strong> of the HS patients, but no differences<br />

compared with the operated si<strong>de</strong> of the HS group. In the PT group the maximum knee flexion<br />

angle in the operated limb was also reduced compared to the non operated limb for both<br />

horizontal and vertical hops. During landing from a horizontal hop the external knee flexor<br />

moment was the predominant moment for the control group but not for patient groups. For the<br />

vertical hop the ankle dorsiflexion moment predominated in all subject groups. The patient<br />

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