Sports Medicine Research: In the Lab & In the Field: Increased Re-Injury Risk after ACL Reconstruction (Sports Med Res)
Thursday, August 18, 2011

Increased Re-Injury Risk after ACL Reconstruction

Ipsilateral Graft and Contralateral ACL Rupture at Five Years or More Following ACL Reconstruction: A Systematic Review

Wright RW, Magnussen RA, Dunn WR, Spindler KP. J Bone Joint Surg Am. 2011;93(12):1159-65.
http://www.ncbi.nlm.nih.gov/pubmed/21776554


Undergoing Anterior Cruciate Ligament Reconstruction (ACLR) and intense subsequent rehabilitation to return to sport is a challenging task. Can you imagine doing it twice? Two years following ACLR, the re-tear rate for the ipsilateral knee or injury to the contralateral knee is about 3% (Wright 2007). However, Paterno et al found a 23% injury rate to either knee in a 12-month follow up. Because these short term follow ups demonstrate such variability in re-injury rates, these individuals need to be followed long term. Therefore, the purpose of this systematic review was to review the literature to compare ipsilateral ACL re-tear rates with contralateral ACL rupture rates in prospective studies with a minimum of five year follow up. It was hypothesized that, in individuals with unilateral ACL injury, the contralateral knee would be at equal or higher risk for injury in a long term follow up. It was also proposed that both knees would have an increased risk of injury long term compared to short term follow ups. A literature review was completed with an inclusion criteria of a minimum duration of 5 year follow up, prospective study design and they must include contralateral and ipsilateral failure rates. Six studies were included in this review and data including subject demographics, graft choice, rehabilitation details, time of follow up and ACL graft and contralateral ACL failure rates were extracted for review. This cohort demonstrated a mean age of 23.4 years at the time of reconstruction and 67% of the subjects were male. Time to follow up was a minimum of five years, but ranged from five to fourteen years. Re-injury rate for the ipsilateral ACL graft was an average of 5.8% (1.8% to 10.4%) and the contralateral ACL injury rate was an average of 11.8% (8.2% to 16%).

The contralateral knee is at twice the risk for injury than the ipsilateral knee. Compared to the two year follow up of 3% injury rate for either knee, the risk for injuring the contralateral knee increases almost 4-fold. There are several hypothesizes for this large increase in injury risk, but no definitive evidence to support them. Clinicians speculate that the contralateral limb takes on a protective role to the reconstructed knee and many times the contralateral knee is neglected during the rehabilitation process. Individuals with non-contact ACL injuries may be at greater risk for adopting these functional adaptations or asymmetries due to poor neuromuscular control. This study did not separate subjects by contact or non-contact injury and asymmetries were not assessed. We speculate that these compensatory movement patterns will place undue stress on the contralateral limb, increasing the risk for injury. Paterno et al found several predictive factors, specifically biomechanical asymmetries, during dynamic tasks that predicted re-injury. Neuromuscular training to influence limb symmetry may be an important part of rehabilitation for these patients. Perturbation training, a specific neuromuscular training protocol, has been found to influence limb symmetry in the short term in ACL injured individuals. Currently, long term follow up of these individuals is being done to monitor their status. However, do you think the benefits seen initially from this neuromuscular training will be maintained at 5 years? How often do you see this occurring in your athletes? Do you perform bi-lateral rehabilitation after ACLR? Do you feel we should start?

Written By: Kathleen White PT, DPT
Reviewed By: Stephen Thomas

Related Articles: 

Hartigan E, et al., Journal of Orthopaedic Research 27, 2009
Fitzgerald GK, et al., Physical Therapy 80, 2000

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