A bone anchor includes a shank having a longitudinal axis and an anchor portion, and a receiver having a base and a pair of upright arms extending upwardly from the base for receiving an elongate rod. The upright arms include opposed interior surfaces with a guide and advancement structure configured to rotatably mate with a closure top to lock an elongate rod within the bone anchor, together with substantially-cylindrical outer side surfaces opposite the interior surfaces. Each upright arm further includes a non-threaded horizontal tool engagement groove formed into the outer side surface, and a vertical tool engagement passage extending into and downward through the upright arm from the top surface through to at least an upper groove surface of each horizontal tool engagement groove.

A system and method for sharing and absorbing energy between body parts. In one particular aspect, the system facilitates absorbing energy between members forming a joint such as between articulating bones.

A surgical technique for lumbar spondylolysis fracture fixation is provided. An instrumentation set for use in the method is also provided. The set includes an anchor configured to attach to a pedicle of a fractured vertebra, a flexible band configured to attach to the anchor, and a hook configured to hook under a lower lamina of a fractured vertebra and further configured to receive the flexible band. The set also includes an inserter for placing the anchor, and a tensioner device having a distal end configured to hold the hook against the lower lamina, and a proximal end configured to secure the flexible band.

In some embodiments, a spinal implant (10, 110, 210, 310, 400) is provided and includes a body portion defining a longitudinal axis. The body portion includes a distal end portion, a proximal end portion, opposed side surfaces that extend between the distal and proximal end portions, and top and bottom surfaces configured and adapted to engage vertebral bodies. The top and bottom surfaces have a surface roughness between 3-4 m. A cavity extends through the top and bottom surfaces defining a surface area that is at least 25% of a surface area of the top surface or the bottom surface. First orifices (24, 124, 224, 324, 426a) are defined through the top surface and second orifices (34, 134, 234, 334, 426b) are defined through the bottom surface. The second orifices are connected to the first orifices by a plurality of channels.