Generalised joint hypermobility leads to increased odds of sustaining a second ACL injury

Key points

1. 0114% of patients with GJH sustained a second ACL injury within 12 months of return to sport, versus 2.9% without GJH (p=0.012)
2. 02GJH was associated with 5.53-fold greater odds of any second ACL injury within 12 months (95% CI 1.67 to 18.29)
3. 03Lifetime hazard of a second ACL injury was 4.24 times higher in the GJH group (95% CI 2.05 to 8.80; p<0.001)
4. 04No differences in patient-reported outcome scores (KOOS, ACL-RSI, K-SES) were found between groups at return to sport
5. 05Patients with GJH returned to sport approximately 2 months earlier on average than those without GJH (9.2 vs 11.5 months; p=0.031)

How it was conducted

Design

Prospective observational registry study (Project ACL, Sweden, 2014-2019)

Participants

225 patients aged 16-50 years treated with primary ACL reconstruction and returning to competition-level sport (Tegner level 6 or above)

Groups

GJH group (Beighton score 5 or above): n=50 (22.2%); non-GJH group: n=175 (77.8%)

Primary outcome

Incidence of a second ipsilateral or contralateral ACL injury within 12 months of return to sport

Secondary outcomes

Lifetime second ACL injury risk via Cox regression; patient-reported outcomes preoperatively and at return to sport

Statistical approach

Univariable logistic regression for 12-month reinjury odds; Cox proportional hazards regression for lifetime survival without reinjury

What they found

• Second ACL injury within 12 months: 7/50 (14.0%) with GJH vs 5/175 (2.9%) without GJH (p=0.012)
• OR for any second ACL injury within 12 months: 5.53 (95% CI 1.67 to 18.29; p=0.005)
• OR for ipsilateral second ACL injury within 12 months: 4.21 (95% CI 1.01 to 17.56; p=0.049)
• OR for contralateral second ACL injury within 12 months: 12.85 (95% CI 1.30 to 126.84; p=0.029)
• Lifetime HR of second ACL injury after return to sport: 4.24 (95% CI 2.05 to 8.80; p=0.0001)
• Cumulative incidence of second ACL injury in patients with 12-month or longer follow-up: 15/39 (38.2%) with GJH vs 14/139 (10.1%) without GJH (p<0.001)
• Mean age at reconstruction: 22.3 years (GJH) vs 25.0 years (non-GJH; p=0.031)
• Time to return to sport: 9.2 months (GJH) vs 11.5 months (non-GJH; p=0.031)
• No significant between-group difference in ACL-RSI at return to sport: 63.3 (GJH) vs 65.4 (non-GJH; p=0.58)
• No significant between-group difference in KOOS4 at return to sport: 72.7 (GJH) vs 73.9 (non-GJH; p=0.60)

Limitations

• The GJH group was small (n=50), and no a priori sample size calculation was performed, increasing the risk of type 2 error for secondary analyses
• A large proportion of registry patients (n=1307) were excluded due to missing Beighton scores, which may limit generalisability and introduce selection bias
• Not all known ACL reinjury risk factors (e.g. concomitant intra-articular injuries, lateral extra-articular tenodesis, specific graft details) were captured or adjusted for
• The Beighton score was recorded post-injury, meaning joint laxity measurements may underestimate true hypermobility prevalence due to restricted motion from surgery

Why it matters

For patients

If you have generalised joint hypermobility and have had ACL surgery, your risk of tearing an ACL again after returning to sport is substantially elevated and worth discussing with your surgeon and physiotherapist before deciding when and how to return.

For clinicians

Routine Beighton score screening before ACL reconstruction return-to-sport clearance is warranted, as GJH independently multiplies reinjury risk and may call for delayed return, more robust graft selection, or lateral extra-articular tenodesis.

For readers

This registry study provides the first prospective evidence quantifying the magnitude of GJH as a risk factor for second ACL injury after reconstruction, strengthening the case for including hypermobility in aggregate reinjury risk calculators.