What is the evidence for and validity of return-to-sport testing after anterior cruciate ligament reconstruction surgery? A systematic review and meta-analysis

Key points

1. 01Only 23% of patients passed return-to-sport test batteries, whether tested before or after returning to sport
2. 02Passing a test battery did not significantly reduce the risk of any subsequent knee injury (RR 0.28, 95% CI 0.04-0.94, p = 0.09) or all ACL injuries (RR 0.80, p = 0.7)
3. 03Passing significantly reduced graft rupture risk by 60% (RR 0.40, 95% CI 0.22-0.73, p = 0.003)
4. 04Passing significantly increased contralateral ACL injury risk by 235% (RR 3.35, 95% CI 1.52-7.37)
5. 05One study found that patients who passed criteria at 6 months were significantly more likely to have returned to sport at both 12 and 24 months post-surgery

How it was conducted

Design

Systematic review and meta-analysis following PRISMA guidelines

Databases searched

PubMed, MEDLINE, Embase, CINAHL, and SPORTDiscus, searched from earliest dates through 7 May 2018

Included studies

18 studies met eligibility criteria; 17 were included in one or more meta-analyses

Participants

Total varied by analysis; 876 patients in the pre-return pass-rate meta-analysis; 565 patients across five studies with ACL re-injury data

Primary outcomes

Proportion passing RTS test batteries; association with subsequent return to sport; association with re-injury risk

Quality assessment

NIH Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies combined with Case-Series checklist; only three studies included a sample size or power calculation

What they found

• Proportional meta-analysis of 8 studies (876 patients) showed 23% (95% CI 8-43%) passed RTS test batteries before return to sport
• Proportional meta-analysis of 3 studies (234 patients) showed 23% (95% CI 18-29%) passed among patients who had already returned to strenuous sport
• All subsequent knee injuries: RR 0.28 (95% CI 0.04-0.94), p = 0.09 - not statistically significant
• All subsequent ACL injuries: RR 0.80, p = 0.7 - no significant reduction in risk
• Graft rupture: RR 0.40 (95% CI 0.22-0.73), p = 0.003 - significant 60% reduction in risk for those who passed
• Contralateral ACL injury: RR 3.35 (95% CI 1.52-7.37) - significant 235% increase in risk for those who passed
• One study (Nawasreh et al.) showed 81% of those who passed RTS criteria at 6 months had returned at 12 months versus 44% of those who failed; at 24 months, 84% vs 46%
• Pass rates across studies ranged from 0% to 79%, with most between 7% and 29%

Limitations

• Only one study investigated whether passing RTS criteria predicted subsequent return to sport, making firm conclusions difficult
• Small total sample sizes in the injury analyses (only 114 patients for any knee injury), creating wide confidence intervals and imprecise risk estimates
• No studies reported player exposure data, so it is unknown whether the group who passed had higher sport exposure contributing to contralateral injury risk
• Study heterogeneity was high, including varied age ranges (14-50 years), graft types, sports, and RTS test battery compositions, limiting comparability

Why it matters

For patients

Patients should know that passing standard return-to-sport tests does not guarantee protection from re-injury and that the opposite knee may actually be at higher risk after clearance.

For clinicians

Clinicians should interpret RTS test battery results cautiously, particularly for contralateral ACL risk, and should consider testing across multiple time points rather than a single clearance assessment.

For readers

This review highlights that current RTS criteria lack strong validity for overall re-injury prevention, and further research is needed to develop and validate better clearance standards.