Interlock to Define a Fixed Spatial Relationship Between Medical Instruments

A system for fixing a spatial relationship between medical instruments can include an interlock component including a body defining an aperture to receive and retain a first needle, a head connected to the body and defining a slot extending parallel to the aperture, and a first magnet at least partially surrounded by the head and disposed between the aperture and the slot. The system can also include a handle to receive and retain a second needle, the handle defining a retaining feature for receiving a portion of the interlock component and including a second magnet positioned adjacent to the retaining feature. The second magnet attracts the first magnet to retain the portion of the interlock component in the retaining feature such that the interlock component is oriented in a desired spatial relationship relative to the handle.