An artificial joint including a main body and a lower portion adapted topivotally engage the main body about a control axis while having a lockingmeansthat is integral with the lower portion. An upper portion adapted to pivotallyengagethe main body about a flexing axis and has an engagement means adapted toengageand disengage the locking means upon the pivoting rotation of the upperportionrelative the main body. A biasing means is adapted to engage both the mainbody andthe lower portion thereby biasing the locking means to engage the engagementmeans,and at least one stopping surface adapted to limit motion between the mainbody andthe lower portion. The locking means is activated when a load is imposed ontheartificial joint and passes through a line posterior to the control axis, andis deactivatedwhen the load passes through a line anterior to the control axis.
