Method, device and navigation aid for navigation during medical interventions

1. A device for navigation during a medical intervention on a non-osseous structure, comprising:

(a) a plurality of navigation aids for navigation during a medical intervention on a non-osseous structure, each navigation aid comprising one marker defining a respective local system of coordinates for determining a position of at least one substructure of the non-osseous structure based on position of the navigation aids in the non-osseous structure, wherein each navigation aid has at least five degrees of freedom to be sensed and wherein each respective local system of coordinates of each navigation aid is locally varying; and

(b) means for sensing the spatial position of each of the plurality of navigation aids in at least five degrees of freedom of each navigation aid.

2. The device as claimed in claim 1 , comprising a plurality of navigation aids and a plurality of sensors for sensing the position of the navigation aids.

3. The device as claimed in claim 1 , comprising means for localizing surgical instruments.

4. The device as claimed in claim 1 , comprising a sensing field, which covers the effective radius of necessary instruments and of the navigation aids.

5. The device as claimed in claim 1 , comprising means for the representation of pre- or intraoperative image data in relation to a necessary instrument.

6. The device as claimed in claim 1 , comprising a plurality of navigation aids and means for generating a field, with which a sensor of each navigation aid can interact.

7. The device as claimed in claim 6 , wherein the field-generating means generate at least one gradient field.

8. The device as claimed in claim 7 , wherein the field-generating means generate at least two gradient fields.

9. A method for navigation during a medical intervention on a non-osseous structure comprising the steps of:

(a) registering a non-osseous structure with preoperative data of the non-osseous structure;

(b) fixing a plurality of navigation aids on or in the non-osseous structure in selected positions, each navigation aid comprising one marker defining a respective local system of coordinates, wherein each navigation aid has at least five degrees of freedom to be sensed;

(c) defining the respective local system of coordinates via each navigation aid, wherein each respective local system of coordinates of each navigation aid is locally varying; and

(d) determining a substructure position of at least one substructure of the non-osseous structure based on the varying positions of the navigation aids and based on the respective varying local coordinate systems.

10. The method as claimed in claim 9 , wherein the non-osseous structure is registered before introduction of the navigation aids, so that the navigation aids can be attached or introduced in a navigated manner.

11. The method as claimed in claim 9 , wherein a preoperative plan for the operation is prepared on the basis of the preoperative data and this plan for the operation is checked and, if appropriate, updated on the basis of the intraoperative data.

12. The method as claimed in claim 9 , wherein each navigation aid further comprises a continuation in the form of a needle for introduction into the non-osseous structure.

13. The method as claimed in claim 10 , wherein the non-osseous structure is immobilized or fixed prior to the registration and wherein the registration of the non-osseous structure takes place in the immobilized state, so that the navigation aids can be introduced with respect to the registered structure in a navigated manner.

14. The method as claimed in claim 13 , wherein, after the attachment or introduction of the navigation aids, the immobilization or fixing of the non-osseous structure is discontinued.

15. The method as claimed in claim 9 , wherein the registration of the non-osseous structure and the registration of the navigation aids take place after the introduction of the navigation aids.

16. The method as claimed in claim 15 , wherein the spatial relationship of each navigation aid in relation to the non-osseous structure is determined only after introduction of the navigation aid.

17. The method as claimed in claim 9 , wherein, after the registration, a transformation is determined, which assigns preoperative image data to intraoperative image data, and vice versa.

18. The method as claimed in claim 17 , wherein an intraoperative transformation is determined between the intraoperative image data by means of a system of coordinates of the navigation aid, so that a direct relationship between pre- and intraoperative data is subsequently available.