COMPENSATORY STRATEGIES THAT REDUCE KNEE EXTENSOR DEMAND DURING A BILATERAL SQUAT CHANGE FROM 3 TO 5 MONTHS FOLLOWING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

BACKGROUND & OBJECTIVE

Research consistently shows that ACLR patients adopt loading patterns that shift the demands away from the ACL reconstructed knee during bilateral tasks. These strategies often persist, with 1 study showing that ACLR patients 13 months post-op had 17% smaller knee extensor moments on the reconstructed limb compared to the healthy limb during a body weight bilateral squat. With most people often returning back to sport at this time, this asymmetrical limb loading is far from ideal and has been linked to increased risk of ACL re-injury.

Bilateral squats are one of the common early introduced exercises following ACLR; however bilateral compound exercises such as the squat can allow compensations that shift the task demands to the healthy limb (inter-limb compensation) or to the hip joint on the reconstructed limb (intra-limb compensation). Therefore, the purpose of this study was to:

1. Assess loading patterns during a bilateral squat in individuals following ACLR at 3 and 5 months post-op
2. Determine how much inter and intra-compensations contribute to reduced knee extensor moments at these time points

METHODS

The authors performed a longitudinal study gathering data at 3-months and 5-months post-op. They recruited ACLR patients aged between 14-40yrs, and who were currently actively participating in ACLR rehab. Rehab was a standard rehab protocol that emphasised early restoration of ROM and progressing off crutches. Rehab consisted of balance and lower extremity strengthening.

The authors gathered kinematic data (peak hip & knee flexion) and kinetic data (peak hip/knee extensor moments, vertical ground reaction forces). After a standardised warm-up, subjects performed squats (arms across their chest - no extra weight added) with each foot on a force plate (placed shoulder width apart) to as low as possible without pain and returned to the standing position. They performed 2x5 consecutive squats at a self-selected pace with a 3min rest between sets.

RESULTS

11 ACLR patients were included in this study (mean age 22, 7F 4M) with various graft types (PT n=6, HS n=1, allograft n=4). 3 had previous ACLR (n=2 contralateral and 1=ipsilateral) at least 2yrs prior to re-injury and all had

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