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Differences in Knee Joint Stabilization Between Children and Adults and Between the Sexes

Background: Differences in knee joint stabilization between children and adults and between the sexes are not fully understood. Purpose: To compare the knee laxity and the dynamic tibial translation between (1) children and adults, (2) girls and boys, and (3) women and men. Study Design: Controlled laboratory study. Methods: Sixty-seven children (aged 8-13 years) and 63 adults (aged 18-30 years) without previous knee injuries participated. Sagittal tibial translation was measured during the instrumented Lachman test at 90 N and 134 N (knee laxity) and during gait (dynamic translation). Tibial translation was recorded with an electrogoniometer. Results: Knee laxity was greater in children than in adults (Lachman test at 90 N: 9.1 ± 2.9 vs 7.3 ± 2.7, respectively; P < .001). In contrast, dynamic tibial translation during gait did not differ between children and adults. Girls and boys did not differ in knee laxity or maximum anterior tibial translation during gait, and men and women did not differ in knee laxity. Women had greater dynamic tibial translation during gait than men (7.8 ± 2.7 vs 5.7 ± 3.0, respectively; P = .004). Conclusion: Children had greater knee laxity than adults, whereas the dynamic tibial translation did not differ. In adults, knee laxity did not differ between the sexes, but dynamic tibial translation was greater in women. Clinical Relevance: Children and men had less dynamic tibial translation during gait in proportion to their maximum knee laxity. The observed less dynamic tibial translation in children and adult men might be related to their reduced risk of sustaining an anterior cruciate ligament injury.