Summary

Half of younger athletes return to competitive sport within 12 months of ACL reconstruction regardless of whether they pass return to sport criteria. This may explain high re-injury rates in this group.

Abstract

Introduction

Return to sport (RTS) after anterior cruciate ligament (ACL) reconstruction is a topic of current interest. The high re-injury rates reported in younger athletes may in part be due to an early return to sport. The purpose of his study was to determine the proportion of younger patients who return to competitive sport at less than 1 year and to examine whether RTS is associated with meeting various RTS outcome criteria.

Methods

A cohort of 1440 athletes (992 males and 448 females) participated. All had a primary ACL reconstruction, a normal contralateral knee, no additional surgery within the first year after the reconstruction and participated in Level I (jumping, hard pivoting, cutting) sports on a weekly basis prior to injury. The proportion of athletes who had resumed competitive sport by 12 months following surgery was recorded along with measurements of knee function (single limb hop symmetry), stability (KT-1000) and self-report outcomes (IKDC subjective). Limb symmetry index scores of greater than or equal to 90, side-to-side difference in anterior knee laxity of 2mm or less and IKDC scores of >95 were considered indicators of readiness to return to sport.

Results

Return to competitive sport rates were significantly higher for athletes aged 25 years and under (48% return rate) compared to older athletes (26-35years: 32% return rate p<0.0001; 46 + years: 19% return rate p<0.001). Males in the 25 and under and 26-35 year age brackets had significantly higher return rates than females (52% vs. 32% and 37% vs. 18% respectively), whereas no sex differences in RTS were seen after 36 years of age. Athletes over 25 years of age had almost twice the odds of RTS if they had a >90 limb symmetry index (p=0.002) and less than 2mm side-to-side difference in anterior knee laxity (p=0.006), whereas there were no differences for athletes 25 years and under. Athletes who had IKDC scores of 95 and above had three times the odds of RTS (p<0.0001) regardless of age.

Conclusion

Almost half of younger athletes return to level I competitive sports within 12 months after ACL reconstruction surgery. Older athletes are more likely to RTS if they pass outcome criteria. That younger athletes are more likely to return to competitive sport within the first year regardless of whether they pass RTS outcome criteria may help to explain the high re-injury rates that are currently being reported in this group.