Is it time we better understood the tests we are using for return to sport decision making following ACL reconstruction? A critical review of the hop tests

Review written by Dr Travis Pollen info

Key Points

  1. To minimize re-injury risk and maximize performance outcomes following ACL reconstruction, clinicians often use hop tests as one component of their return to sport testing battery.
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After anterior cruciate ligament reconstruction (ACLR), athletes are at high risk of a second ACL injury (ipsilaterally or contralaterally) and reduced athletic performance. As such, the decision to clear an athlete to return to sport following ACLR is often a challenging one. To minimize injury risk and maximize performance, clinicians rely on time since surgery, physical examination, patient-reported subjective function, and a battery of functional tests (e.g. strength and hop tests) (1).

Hop testing traditionally consists of one or more of the following tests: single-leg hop for distance, triple hop for distance, crossover hop for distance, and six-meter timed hop (see Figure 1). Hop tests are particularly common because they’re easy to administer and score. The criterion for passing hop tests is based on the limb symmetry index, which is calculated by dividing the distance hopped on the involved limb by the distance hopped on the uninvolved limb and multiplying by 100. A limb symmetry index of 90% is typically considered the threshold for passing.

It has long been believed that athletes who pass functional tests are at reduced risk of re-injury. This belief has come into question, however, based on recent meta-analyses (2,3). Given the uncertainty surrounding hop testing, the objectives of this review were: (1) to critically examine hop tests’ utility for return to sport decision-making, and (2) to recommend best practices for using hop tests.

After ACL reconstruction, athletes are at high risk of a second ACL injury and reduced athletic performance.
Athletes often achieve 90% limb symmetry on hop tests while still having substantial deficits at the knee (through compensatory power generation from the ankle and hip).



The authors explored several topics in this critical review: hop tests’ measurement properties, the validity of the contralateral limb as a comparator, alternatives to hop tests, and the importance of assessing movement quality (in addition to hop distance).

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