Return to Sport Testing after ACL Reconstruction: Beyond Time

Visual Element: An interactive "RTS Battery" dashboard. Users can hover over different tests (Hop Test, Isokinetics, Drop Jump) to see the "Passing Criteria" and a video clip of the test being performed.

For decades, the clearance for Return to Sport (RTS) after ACL reconstruction was based on the calendar: "It's been 6 months, the graft is healed, go play." The result? A re-tear rate of up to 20-30% in young athletes.

We now know that Time is a necessary, but not sufficient, criterion. The graft may be biological (ligamentized), but the Neuromuscular Control may be absent. The brain has rewired to protect the knee, leading to compensatory patterns that put the athlete at risk.

Modern RTS is a battery of objective biological, functional, and psychological tests.

Part 1: The Biology (Time Criteria)

Despite functional readiness, biology cannot be cheated.

• Ligamentization: The graft goes through necrosis, revascularization, and remodeling. This process takes at least 9 months (and arguably up to 2 years).
• The Rule: No RTS (Level 1 pivoting sports) before 9 months. Every month delayed until 9 months reduces re-injury risk by 51%.

Part 2: The Function (Physical Testing)

We aim for a Limb Symmetry Index (LSI) of > 90% (The injured leg is 90% as good as the uninjured leg).

1. Strength Testing

Manual Muscle Testing (pushing against the hand) is useless. You need objective numbers.

• Isokinetic Dynamometry (Biodex): The Gold Standard.
  • Quad Strength: Peak torque/body weight > 3.0 Nm/kg.
  • Hamstring/Quad Ratio: > 60% (essential for dynamic ACL protection).
• Hand-Held Dynamometry: A cheaper alternative if fixed properly.

2. Hop Tests (Power & Control)

A battery of 4 tests. Measure distance and quality.

1. Single Hop for Distance.
2. Triple Hop for Distance.
3. Crossover Hop for Distance.
4. 6-Meter Timed Hop.

Passing Criteria: LSI > 90% on all 4 tests.

3. Movement Quality (Video Analysis)

Distance isn't everything. If they hop 2 meters but land in massive Dynamic Valgus (knee caving in), they fail.

• Drop Vertical Jump: Jump off a box, land, and immediately jump up.
  • Look for: Knee Valgus, Trunk Lean (ipsilateral), Heavy Landing.
  • LESS Score: Landing Error Scoring System.

Part 3: The Psychology (The Head Game)

This is the hidden killer. An athlete can have strong quads but be terrified of pivoting.

• Kinesiophobia: Fear of movement / re-injury.
• Consequence: They "stiffen" the knee, protect the limb, and overload the contralateral side.
• Assessment: ACL-RSI (Return to Sport after Injury) Scale.
  • A 12-item questionnaire.
  • Score: > 60-65 suggests psychological readiness. < 50 suggests high fear and risk of non-return.

Part 4: The RTS Decision Continuum

RTS is not a binary "Yes/No" on one day. It is a phased continuum.

1. Return to Participation: Training, drills, no contact.
2. Return to Sport: Match play, full contact.
3. Return to Performance: Playing at pre-injury level.

Conclusion

Clearance is a shared decision between Surgeon, Physio, and Athlete. The Checklist:

1. Time > 9 months.
2. Full ROM and no effusion.
3. Quad/Hamstring LSI > 90%.
4. Hop Test LSI > 90% with good mechanics.
5. ACL-RSI > 60.

If they don't pass, they don't play. Be the bad guy now to save their knee later.

ACL-RSI Calculator

Use our interactive tool to calculate your patient's psychological readiness score.