Case Study: 24-year-old Female Soccer Player | 7 Months After ACL Surgery
She passed her hop tests. Her quad strength looked good. Her surgeon cleared her. She “felt great.”
But the force plates told a different story.
What the Numbers Revealed
We measured how she jumped and landed on each leg separately:
| What We Measured | Surgical Leg | Healthy Leg | Symmetry |
| Jump Height | 18.2 cm | 22.4 cm | 81% |
| Push-Off Power | 142 N·s | 178 N·s | 80% |
| Braking Ability | 4,210 N/s | 6,380 N/s | 66% |
| Landing Force | 1,840 N | 2,120 N | 87% |
Her ability to slow down and absorb force was 34% weaker on her surgical side.
She was landing like she still expected it to hurt – even though it didn’t.
Why This Matters
Recent research studied 49 basketball players after ACL reconstruction and found that athletes with weaker quads showed significantly worse results on force plate testing -especially in:
→ Braking ability (how well you decelerate)
→ Push-off power (explosive jumping)
→ Reactive strength (quick, repeated movements)
Traditional hop tests missed these deficits. Force plates caught them.
Studies confirm that these hidden asymmetries persist even when athletes “pass” standard return-to-sport testing.
What We Changed
Instead of clearing her to play, we:
✓ Extended her jumping and landing program by 6 weeks
✓ Focused on exercises that trained her to absorb force better
✓ Re-tested monthly to track her progress
✓ Set her target: less than 10% difference between legs
By month 9, her braking ability was 94% symmetrical. Push-off power: 96%.
Now she was actually ready!
The Takeaway
Passing return-to-sport tests doesn’t always mean you’re ready to return.
Force plate technology reveals what the eye can’t see:
- Who’s unconsciously protecting their surgical leg
- Who’s making their healthy leg do extra work
- Who needs more time – even when they “feel fine”
Research suggests aiming for less than 10% difference between legs may reduce re-injury risk better than the older 15% target.
Traditional hop tests measure the result. Force plates measure how you got there.
If you want to make sure your knee is really ready for sport, book in with one of our expert physiotherapists to test your knee thoroughly with our Force Decks.
