Surgical referencing unit, surgical instrument and surgical navigation system

Surgical instrument, comprising:

• a surgical referencing unit for a surgical navigation system, with which navigation system at least one of a spatial position and orientation of the reference unit is determinable,
• said referencing unit comprising a base body and at least one marker element arranged on the base body, a spatial position of said at least one marker element being determinable by the navigation system, the at least one marker element being movably mounted on the base body,
• the referencing unit comprising a first interface device which is configured to be brought into engagement with a second interface device provided on the surgical instrument in a connected position,
• wherein the engagement of the first interface device and the second interface device mechanically moves the at least one marker element into a predefined marker element position with respect to the base body.

Surgical navigation system, comprising:

• at least one referencing unit, and
• at least one detecting device for detecting at least one of a spatial position and orientation of the referencing unit,
• said referencing unit comprising a base body and at least one marker element arranged on the base body, a spatial position of said at least one marker element being determinable by the navigation system, the at least one marker element being movably mounted on the base body,
• the referencing unit comprising a first interface device which is configured for engagement with a second interface device provided on a surgical instrument or an implant in a connected position,
• wherein the engagement of the first interface device and the second interface device mechanically moves the at least one marker element into a predefined marker element position with respect to the base body.