Derotation apparatus for treating spinal irregularities

A polyaxial bone fastener for correcting a spinal deformity comprising:

• a bone screw including a head and a threaded shaft extending distally from the head for inserting into a vertebral body, the shaft defining a screw axis;
• an offset connection assembly having a ball shaped portion positioned over the head such that the screw axis lies in the ball shaped portion, the ball shaped portion adapted to move polyaxially relative to the bone screw head, the offset connection assembly further having an off-axis rod opening positioned in the ball shaped portion and adapted to receive a rod along a rod axis which is laterally offset from the screw axis;
• and
• a housing disposed over the bone screw and adapted to sandwich the offset connection assembly.

A polyaxial bone fastener for correcting a spinal deformity comprising:

• a bone screw including a head and a shaft extending distally from the head for inserting into a vertebral body, the shaft defining a screw axis;
• an offset connection assembly positioned over the head and adapted to move polyaxially relative to the bone screw, the offset connection assembly having an off-axis rod opening adapted to receive a rod along a rod axis which is laterally offset from the screw axis;
• and
• a housing disposed over the bone screw and adapted to sandwich the offset connection assembly to clamp the offset connection assembly;
• and
• wherein:
• the head includes a drive feature for interfacing with a drive instrument to drive the bone screw into the bone;
• the housing and the offset connection assembly have a through hole sized to receive the drive instrument to allow the drive instrument to interface with the drive feature of the head.