An anterior cruciate ligament (ACL) injury is a common knee injury, especially among soccer and basketball athletes who they require to pivot, jump and change directions rapidly.

Whether reconstruction surgery or conservative treatment is taken, the most common complication after ACL injury is recurrent knee instability. Only about 65% of patients return to their pre-injury level of competitive sport within 2 years after ACL rupture, while only 38% remain at this level of the sport.

Return to Sport (RTS) performance tests objectively measure the athletes’ readiness to return to unrestricted sports training or play, where we will focus on their functional performance and sports-specific movements.

The 5 main elements in RTS testing include:

  1. Quiet knee
  2. Isokinetic muscle strength
  3. Functional testing
  4. Patient-reported outcome measure
  5. Time

1. Quiet Knee

Before getting into sport-specific movements, a quiet knee has to be achieved whereby certain clinical measures are taken, including:

  • Full knee range of motion
  • Full quadriceps activation
  • Little to no pain
  • No swelling

If you did not meet any of these common clinical criteria, then returning to competitive sport is not advisable as it will increase the risk of reinjuries.

2. Isokinetic Muscle Strength

The quadriceps strength deficit was the largest predictor of knee reinjury of all the RTS batteries used. With every 1% of improved quadriceps strength symmetry, there is a 3% reduction in reinjury rate.

An isokinetic testing machine like the Biodex system or hand-held dynamometer can be used to objectively measure your quadriceps muscle strength.

3. Functional Testing

To assess dynamic stability & power

(A) Hop Tests

Hop test is the main performance measure in RTS testing. It is performed on each leg individually, comparing the injured side to the normal side and aiming for 90-95% limb symmetry index (LSI), and achieving maximum values on the tests.

The most commonly used hop tests include:

Single leg hop

  • Assess distance, controlled knee flexion, triple extension, trunk lean, tibial translation

Triple hop

  • Assess distance, landing mechanics, power production, ground contact time

6m timed hop

  • Assess sprinting technique, power production, ground contact time

Crossover hop

  • Assess distance, landing strategies, frontal plane knee control, trunk control

(B) Y-Balance Test (YBT)

(C) Agility T-Drill

4. Patient-reported Outcome Measure

5. Time

Prepared by

Charlotte Yip Chiang Yee

Physiotherapist of Your Physio Ampang

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