Quadriceps muscle strength of adolescents recovers faster than those of adults after anterior cruciate ligament reconstruction using hamstring graft

Abstract

Objectives

Knee muscle strength recovery after anterior cruciate ligament reconstruction is usually evaluated using isokinetic limb symmetry index to help take the decision to allow return to the previous sport. However, the role of age on knee strength recovery is not well known. So, we aimed to compare the isokinetic knee muscle strength recovery according to age at 4 and 7 months after anterior cruciate ligament reconstruction using hamstring graft.

Methods

From a historical cohort (2018-2023) of patients who completed isokinetic monitoring at 4 and 7 months after anterior cruciate ligament reconstruction using hamstring graft, two groups were compared according to age: ≤19 and ​> ​20 years old. The quadriceps and hamstring limb symmetry indexes were studied as the main parameters. A multivariate analysis was realized to assess the weight of potential inter-subject explanatory parameters on knee strength evolution.

Results

Two hundred fifty-three adolescents were compared with 247 adults. The adolescent quadriceps symmetry index at 60°/s was significantly higher than that of adults (79% vs 72% and 88% vs 82% at 4 and 7 months of follow-up, respectively). The hamstring symmetry index was not statistically significantly different. No inter-subject explanatory parameters were found after the multivariate analysis.

Conclusion

Knee strength recovers faster in adolescents than in adults after anterior cruciate ligament reconstruction using hamstring graft. This result should be carefully considered because adolescents could be exposed to return to sport too early, while the risk of graft rupture is still high, if strength cutoff is only considered.

Level evidence

III.