One in Three Paediatric Athletes Suffer Secondary ACL Injuries

With paediatric ACL tears on the rise, we are also becoming more aware of the high risk of reinjury. An important meta-analysis found a secondary-injury rate of 15% among all people with ACL reconstructions (ACLR).2 We say “secondary injury” because that rate includes injuries on both the knee ipsilateral to the ACLR and the contralateral knee. After a unilateral ACLR, both knees are at increased risk of future ACL injury. 

 The most striking numbers are among younger patients. The subset of ACLR patients younger than 25 have a 21% secondary-injury rate. These young athletes with a previous ACLR demonstrate a risk of future ACL injury 30 to 40 times greater than that of young, uninjured athletes. When we add athletic participation and younger age, the numbers continue to tell a story of mounting risk. Among athletes under age 18, one in three ACLR patients experienced a secondary injury.3 Secondary injuries tend to occur early in the return-to-play period.
 
Improved secondary prevention methods seem warranted. Experts have hypothesised that paediatric patients should wait two years before returning to sport.4 Dekker et al. found a protective effect for each month after six months that return to sport was delayed.3 However, they were the first to have that finding. Older studies have found no effect of early return to sport (<6 months) on graft tears.5-7  
 
Physiotherapy also plays a role in secondary prevention of ACL injuries. All exercise therapy programs seek to restore strength and flexibility to the injured leg. Neuromuscular training has been hypothesised to improve outcomes, by improving dynamic control of lower limb movements in at risk positions.  
 
Two studies with amateur and semi-professional football players found that adding proprioceptive warm-up exercises such as these to the routine decreased ACL injuries 85% and 88%.9,10 

References

1. Zbrojkiewicz D, Vertullo C, Grayson JE. Increasing rates of anterior cruciate ligament reconstruction in young Australians, 2000–2015. Medical Journal of Australia. 2018 May; 208 (8): 354-8. 
2. Wiggins AJ, Grandhi RK, Schneider DK, Stanfield D, Webster KE, Myer GD. Risk of secondary injury in younger athletes after anterior cruciate ligament reconstruction: a systematic review and meta-analysis. The American Journal of Sports Medicine. 2016 Jul; 44 (7): 1861-76. 
3. Dekker TJ, Godin JA, Dale KM, Garrett WE, Taylor DC, Riboh JC. Return to sport after pediatric anterior cruciate ligament reconstruction and its effect on subsequent anterior cruciate ligament injury. JBJS. 2017 Jun 7; 99 (11): 897-904. 
4. Nagelli CV, Hewett TE. Should return to sport be delayed until 2 years after anterior cruciate ligament reconstruction? Biological and functional considerations. Sports Medicine. 2017 Feb 1;47(2):221-32. 
5. Shelbourne KD, Sullivan AN, Bohard K, Gray T, Urch SE. Return to basketball and soccer after anterior cruciate ligament reconstruction in competitive school-aged athletes. Sports Health. 2009 May;1(3):236-41. 
6. Howell LC, Taylor CM. Brace-free rehabilitation, with early return to activity, for knees reconstructed with a double-looped semitendinosus and gracilis graft. JBJS. 1996 Jun 1;78(6):81425. 
7. Glasgow SG, Gabriel JP, Sapega AA, Glasgow MT, Torg JS. The effect of early versus late return to vigorous activities on the outcome of anterior cruciate ligament reconstruction. The American Journal of Sports Medicine. 1993 Mar;21(2): 243-8. 
8. Relph N, Herrington L, Tyson S. The effects of ACL injury on knee proprioception: a metaanalysis. Physiotherapy. 2014 Sep 30; 100 (3): 187-95. 
9. Mandelbaum B, Silvers H, Wantanabe D, et al. Effectiveness of a Neuromuscular and Proprioceptive Training Program in Preventing Anterior Cruciate Ligament Injuries in Female Athletes. The American Journal of Sports Medicine. 2005; 33 (7): 1003-1010.
10. Caraffa A, Cerulli G, Projetti M, et al. Prevention of anterior curciate ligament injuries in soccer – a prospective controlled study of proprioceptive training. Knee Surg, Sports Traumatol, Arthroscopy. 1996; 4: 19-21.