Sports Medicine Research: In the Lab & In the Field: Let’s Hop To It: ACL Patients Not as Good (Sports Med Res)
Wednesday, May 24, 2017

Let’s Hop To It: ACL Patients Not as Good

A Critical Analysis of Limb Symmetry Indices of Hop Tests in Athletes After Anterior Cruciate Ligament Reconstruction: A Case Control Study

Gokeler A, Welling W, Benjaminse A, Lemmink K, Seil R, & Zaffagnini S. Orthopaedics and Traumatology: Surgery and Research. 2017; Published online ahead of print
http://dx.doi.org/10.1016/j.otsr.2017.02.015            

Take Home Message: Athletes after an anterior cruciate ligament (ACL) reconstruction perform poorly bilaterally in hop testing when compared with healthy matched controls. 

We have recently had a few posts on Sports Med Res investigating return to play testing after anterior cruciate ligament (ACL) reconstructive surgery (see below).  Oftentimes, the surgical side is compared to the nonsurgical side in regard to strength, function, and range of motion.  Many clinicians are increasingly using a series of single-limb hop tests as functional assessments. However, the contralateral limb may be an inappropriate comparison if it is also weak or functioning at suboptimal levels.  The authors of this case-control study compared both limbs of athletes with a previous history of an isolated ACL reconstruction to control athletes on hop test performance.  Fifty-two athletes performed a single-leg hop, a triple hop, and a side hop at an average of 7 months post-surgery. These results were compared to healthy athletes.  The authors compared the involved to the uninvolved limb of the ACL reconstructed participants (limb symmetry index) and found that a little over 80% were ≥ 90% in comparison to their healthy limb, with an average limb symmetry index of 95% on the 3 hop tests.  On average, athletes after an ACL reconstruction hopped shorter distances with both limbs compared with healthy control data for single-leg-hop and triple-hop tests.  Males who had an ACL reconstruction also performed worse on the side hop compared with healthy controls. 

These authors found that despite most ACL reconstructed participants having an acceptable limb symmetry index (> 90%), they still had impaired performance compared with matched healthy participants.  Therefore, it remains questionable as to whether the uninvolved limb is an appropriate comparison at around 7 months post-surgery.  However, this should be interpreted with caution because the control normative data was collected by other authors at an earlier date, and this may cause variations and is a limitation of the comparison.  It would be interesting to see how the results would compare if the uninvolved limb was tested shortly after injury.  There was another recent post which used strength testing of the uninvolved limb shortly after the time of injury and found this to be a better comparison for achieving post-surgical gains.  The authors also introduced a side hop test, which is less commonly used.  They reported that ACL reconstructed males performed poorly compared with healthy controls.  However, it would be interesting to see if you could incorporate an assessment of the quality of the side hop (e.g., looking for valgus collapse), specifically in the female participants.  As clinicians, we should remember that there is a deconditioning that happens bilaterally after a surgical procedure.  This study offers more evidence to support that it might be inappropriate to compare the involved limb to the uninvolved limb at the time of post-operative testing (7 months post-surgery in this case).  Baseline testing, normative data, or uninvolved performance close to the time of injury may be best for comparison. 

Questions for Discussion:  When do you assess uninvolved strength or function in an ACL case?  Are there other hop tests that you utilize for making return to play decisions?
  
Written by: Nicole Cattano
Reviewed by: Jeffrey Driban

Related Posts:
Variability in Leg Muscle Power and Hop Performance After ACL Reconstruction



Gokeler, A., Welling, W., Benjaminse, A., Lemmink, K., Seil, R., & Zaffagnini, S. (2017). A Critical Analysis of Limb Symmetry Indices of Hop Tests in Athletes After Anterior Cruciate Ligament Reconstruction: A Case Control Study Orthopaedics & Traumatology: Surgery & Research DOI: 10.1016/j.otsr.2017.02.015

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