Summary

12 months after ACLR, most children demonstrate significant deconditioning on their uninjured leg relative to a normative population

Abstract

Introduction

Return to sport (RTS) functional testing post-ACLR relies on the comparison against the healthy limb (with >90% performance considered satisfactory). Limited normative paediatric population data exists. In addition, the effect of leg dominance in this population is unknown. We hypothesised that the normal limb (uninjured limb) in paediatric patients 12 months post-ACLR would differ from the normal population values, in functional RTS testing. In addition, we hypothesized that limb dominance would account for significantly better functional scores which may account for misleading RTS results post surgery.

Methods

87 healthy children (mean age 14 years 8 months) were recruited from local schools and community sports clubs. This normative group underwent routine RTS functional testing to gain control values. 87 post-ACLR children (matched for age, height, weight and Tegner activity level) underwent RTS functional testing in our research institute. Study participants in both groups carried out the following functional tests: knee range of motion, hamstring strength, quadriceps strength, hop for distance, hop for height and cross-over hop. Differences between the normal (uninjured) limb of the post-ACLR group and the normal healthy group were highlighted. The effect of leg dominance on RTS testing performance was also assessed within the normal group.

Results

The normal limb of the post-ACLR group performed significantly worse than the normal (control) population in all functional testing results hamstring strength (control, 85.33±42.84 Nm; non-injured ACLR, 52.3±45.23 Nm; p=0.0001), quadriceps strength (control, 183.6±75.6 Nm; non-injured ACLR, 143.16±115.98 Nm; p=0.02), hop for distance (control, 86.52±28.19 cm; non-injured ACLR, 61.84±25.6 cm; p=0.0001) and hop for height (control, 24.8±7.15 cm; non-injured ACLR, 21.76±7.48cm; p=0.0001). Leg dominance in the normal population significantly positively effects quads strength (4% higher in dominant limb; dominant, 315.1±99.4Nm; non-dominant, 302.9±92.2Nm; p=0.006), triple hop (3% higher in dominant limb; dominant, 434.2±88.1cm; non-dominant, 423.2±87.0cm; p=0.006) and hop height (7% higher in dominant limb; dominant, 23.8±8.8cm; non-dominant, 22.2±7.9cm; p=0.01), but has no significant effect on other tests.

Conclusion

RTS functional testing at 12 months post-ACLR demonstrates deconditioning in the normal limb relative to a healthy age-matched paediatric population. This may imply contralateral injury risk and consideration should be given to longer rehabilitation periods. The effect of limb dominance in the paediatric population does not significantly affect outcome of RTS testing. Hence, limb dominance is unlikely to cause false positives or false negatives in the RTS testing.