ABSTRACT
[Objective]To measure the in vivo knee joint reaction force in a rabbit model of tibial diaphyseal lengthening.[Method]Sixteen immature (8 weeks old) New Zealand White rabbits were underwent 30% (left) tibial diaphyseal lengthening at a rate of two 0.4 mm incremental lengthenings per day.The knee joint reaction force was measured at the end of lengthening (8 rabbits,13 weeks old) and 5 weeks later (8 rabbits,18 weeks old).An instrumented bilateral distractor and an extensometer were fixed cross the knee joint.The joint distraction force and distraction displacement were measured immediately after each incremental distraction of the joint.[Result]The joint reaction force on the lengthened side was significantly higher than that of the control side at both time points (44.4?7.8 N v.27.2?4.0 N at 13 weeks of age,44.3?6.5 N v.31.3?3.0 N at 18 weeks of age).[Conclusion]The knee joint reactive force could be increased in 30% tibial disphyseal lengthening which potentially could lead to the risk of damage to artic ular cartilage.