Why You Need To Use The Limb Symmetry Index

assessment Feb 15, 2018

What Is The Limb Symmetry Index (LSI)?

The Limb Symmetry Index (LSI) is a ratio of performance between limbs that is frequently used to assess the function of the lower limb and track the progression of rehabilitation post-Anterior Cruciate Ligament reconstruction. 

The Limb Symmetry Index (LSI)  is an excellent guide to objectively determine discrepancies in your patient’s upper and/or lower limb strength, function, and mobility.

The LSI is calculated by taking the average of any test scores for the affected limb, divided by the unaffected limb, multiplied by 100 to obtain a percentage difference between limbs.

Clinically, it is an easy-to-use, quick measure that can provide valuable data for baseline and progression purposes. It has been shown to be of significant importance in deciding when an athlete is ready to return to sport after anterior cruciate ligament (ACL) injury, with percentage values for knee extension and flexion strength equal to or above 90% considered to be satisfactory (Abrams et al., 2014).

Why Use The Limb Symmetry Index (LSI)?

Recent studies have also shown that:

  • At 1 year post-ACL injury, those with normal knee function had LSI values greater than 90% for the single-leg, cross-over, and triple hop tests - the LSI hop testing battery (Wipfler et al., 2011)
  • An LSI score discrepancy of less than 15% is recommended in a drop vertical jump landing force for all athletes, regardless of sport, prior to return to play (Myer, Paterno, Ford, Quatman, & Hewett, 2006)
  • The LSI be used in conjunction with a range of other tests and criteria for appropriate decision-making regarding return to play, including reference to healthy, normative values if data is available for reducing the risk of injury and re-injury (Abrams et al., 2014)

What Tests Can Be Used To Calculate The Limb Symmetry Index (LSI)?

The Limb Symmetry Index (LSI) can be calculated as the ratio of the involved limb over the uninvolved limb using almost any objective test.

At Movement Assessment Technologies we choose to use tools like The MAT and Hop MAT to easily perform LSI tests.

Example of tests you might choose when calculating the Limb Symmetry Index include:

  • Star Excursion Balance Test (SEBT)
  • Knee extension isometric strength
  • Knee Flexion isometric strength
  • Single Leg Hop for distance
  • Single Leg Side Hop for distance
  • Crossover Hop for distance
  • Triple Hop for distance
  • 6 Metre Hop for time
  • Lateral Hop test
  • Single leg Vertical Hop test

The strength of using the Limb Symmetry Index is that by using a battery of tests it can help to identify true reduced limb function in your patients and clients and account for any outliers in testing.

At MAT we design a range of products to help you assess and calculate the Limb Symmetry Index score for your patients and clients.

Click here to visit our range of Movement Assessment Tools.

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