An apparatus comprises a pair of bone attachment devices and a crosslink device for a spinal fixation system or other implant arrangement. The bone attachment devices include a head with socket to receive a spinal rod or other elongate element and the crosslink device includes a pair of bridging members each having an end section for connecting with the bone attachment devices. An interconnection device situated between the bridging members receives the bridging members and allows translational and rotational freedom therebetween while being operable to secure the bridging members in position relative to one another. A pair of engaging members are structured to engage the head of the respective bone attachment device and bear against the respective adjacent end of crosslink device to lock the crosslink and the bone attachment device in a rigid construct are also included.