Physiological knee laxity during pubertal growth.

BACKGROUND

The relationship of physiologic laxity to age has been reported in only cross-sectional studies. The current investigators suggest further investigations, to include Tanner staging in order to understand the extent to which increases in maturity influence alterations in laxity.

MATERIALS AND

METHODS

A two-phase (cross-sectional and longitudinal) study assessed knee joint laxity and flexibility in 172 normal adolescents, using a KT 2000 arthrometer, anthropometric measurements, and Carter and Wilkinson tests. Correlation of these evaluations was done with gender and Tanner stage. Data from clinical and KT 2000 measurements at the initial evaluation were analyzed as the cross-sectional, single assessment phase of the study. The longitudinal phase of the study reviewed modulation of laxity and flexibility, with growth by repeated examination of the above tests in individual subjects during their adolescent growth phase.

RESULTS

Increased flexibility was seen significantly more frequently in females than males in both study phases. Age, Tanner stage, and anthropometric values were not significantly associated with laxity in the cross-sectional study. In the longitudinal study, an inverse relationship was demonstrated between Tanner stage and KT 2000 laxity measures after adjusting for other variables. Sequential evaluation showed a progressive decrease of sagittal laxity at the onset of Tanner stage 2. Laxity was significantly greater in adolescents, with signs of joint physiologic hyperflexibility.

CONCLUSION

Evaluation of laxity and flexibility during the adolescent growth phase is important for better definition of muscle strengthening or flexibility programs, to avoid functional overloads and injury.