Low rates of patients meeting return to sport criteria 9 months after anterior cruciate ligament reconstruction: a prospective longitudinal study

Key points

1. 01At 6 months only 3.2% of patients passed all return-to-sport criteria, rising to just 11.3% by 9 months.
2. 02Hop tests and strength improved over time, but self-reported knee function (IKDC) did not.
3. 03Quadriceps strength was a major sticking point, with 46.8% still failing the slow-speed strength test at 9 months.
4. 04The findings support waiting at least 9 months before returning to sport, since most patients are not test-ready earlier.

How it was conducted

Design

Prospective longitudinal study (Level of evidence III)

Participants

62 patients after ACL reconstruction following standardized rehabilitation

Testing timepoints

Battery performed at 6.5 plus or minus 0.7 months and 9.5 plus or minus 0.9 months

Test battery

LESS jump-landing, single/triple/side hop (LSI greater than 90%), isokinetic quadriceps/hamstrings at 60/180/300 degrees per second, IKDC, ACL-RSI

Pass criteria

LESS less than 5, IKDC within healthy 15th percentile, ACL-RSI greater than 56

What they found

• At 6 months, 2 of 62 patients (3.2%) passed all return-to-sport criteria.
• At 9 months, 7 of 62 patients (11.3%) passed all criteria.
• Hop and strength measures improved over time, but IKDC did not.
• At 9 months, 46.8% of patients failed the strength criterion at 60 degrees per second.

Limitations

• Single cohort of 62 patients with no control group, limiting generalizability.
• Level III evidence and observational design rather than a controlled trial.
• Follow-up ended at roughly 9 months, so longer-term test passage and actual return-to-sport outcomes are unknown.
• Pass rates depend on the specific cut-offs chosen, which may differ across clinics.

Why it matters

For patients

If you have had ACL reconstruction, expect that you may not be physically test-ready to return to sport even at 9 months, so be patient and keep working on strength.

For clinicians

Use a multifactorial test battery and target quadriceps strength and patient-reported function, since these are the most common reasons patients fail return-to-sport criteria.

For readers

Most patients do not meet objective return-to-sport benchmarks by 9 months after ACL reconstruction, supporting a cautious, criteria-based timeline.