MED EL BONEBRIDGE. Active Bone Conduction Implant. Bruce Black MD

Transcription

1 MED EL BONEBRIDGE Active Bone Conduction Implant

2 Bonebridge components. The active bone conduction implant is below, the external Amade receiver/processor above.

3 Bonebridge hardware. The Amade external processor (above) is sited over the implant (below), which is fixed to the calvarium, stimulating the ipsilateral or contralateral ear.

4 Components of the implant. Sound is processed into current by the Amade, induction coils transmit the signal, and this is converted into vibration of the transducer.

5 Bonebridge implant component. The Amade processor is held in position, aligning the induction coils, by opposing magnets. The neck of the implant can be bent to adapt to the surgical situation.

6 Ipsilateral stimulation. The sensorineural reserves must be above the shaded level thresholds for optimal implant performance. Contralateral stimulation requires normal hearing in the better ear.

7 A bone conduction aid is used before surgery to test the patient s response to BC type hearing stimulation.

8 Torque wrench used to judge optimal screw tension (10-15).

9 Detail of the torque wrench gauge.

10 Phillips type screwdriver used with the torque wrench.

11 Screwdriver-torque wrench assemblage.

12 Sizer device used to check the width and depth of the bony well, and to provide exact siting and depth of the required drill-holes.

13 Bonebridge implant surgical tray. Includes the implant, dummy for pocket/siting, the drill-hole guide and fixation screws.

14 Bonebridge surgical site preparation. The adhesive drape is stapled closely along the hairline to prevent hair from fouling the site.

15 Keyhole insertion technique. An auricular incision is used to avoid proximity to the implant that may cause dehiscence or infection risks. The post-aural skin is widely undermined.

16 An initial skin flap is raised on a base approximately 3 cm diameter.

17 A pinna base periosteal flap is then raised, passing deep to the conchal cartilage. The flap is used to provide extra implant cover at the end of the procedure.

18 Sub-periosteal pocket is created postero-superior to the mastoid to receive the implant. As opposed to CI cases, the pocket is created larger, to permit some implant mobility in situ. This aids final positioning and fixation.

19 Once the pocket is created, a dummy implant is used to check the dimensions and direction.

20 Insertion of the dummy to check the pocket may be facilitated by moistening the site.

21 Once in the loose pocket, the dummy can be advanced using a tail grip.

22 Final site position. The dummy is withdrawn by traction on the tail.

23 Exposure of the supra-meatal triangle. The implant well is created with the anterior edge close to the EAC.

24 Implant well creation. If necessary, the dura and lateral sinus may be egg-shelled and compressed away from the well to permit insertion of the drill-hole fixation guide.

25 Initial insertion of the drill-hole guide. A tight fit in the well is unnecessary, as the screw fixation supplies the necessary implant stability.

26 The peri-incisional skin is manoeuvred over the drill guides.

27 Positioning the skin over the lower drill guide after the upper guide has been positioned. Clearing soft tissue and slightly flattening the bone at the screw sites gives optimal stability.

28 Once the guidance dummy is well positioned, the drill as supplied will create holes 4 mm deep. Irrigate profusely to avoid burnt bone.

29 Creating the second screw hole. A straight instrument is placed in the initial hole to prevent screw guide movement and incorrect hole siting that may impede screw insertion.

30 Screw hole in the upper mastoid.

31 Second screw hole in the lower mastoid.

32 Insertion of the implant. The neck may be substantially bent to adapt to the site of the screw holes, and to site the flanges flush on the bone. A larger pocket facilitates this positioning by allowing some implant mobility.

33 Final positioning should site both the implant screw sites directly over the drill holes, without intervening soft tissue and firmly flush on to the bone.

34 Fixation 4 mm screws. The grey screw has a slightly larger diameter, and is used if a gold screw seems loose.

35 Implant fixation. Both screws are applied partially, then more firmly.

36 Lower screw fixation. Undermining the post-aural skin permits wound mobility that facilitates exact implant siting over this hole.

37 A torque wrench is used to complete screw fixation to approx. 15 pressure.

38 Final implant position after screw fixation.

39 Wound closure. The pinna-based periosteal flap is lowered over the implant body to provide a vital tissue layer between device and wound to minimise infection/dehiscence risk.

40 Final wound appearance. The incision is slightly larger than that used for CI or VSB purposes, but remains remote from the implant and exerts no tension on the suture line.

41 Post-implant appearances. Amade processor in place, held to the hair by a micro-clip to prevent loss. The surgical wound is seen on the auricle.