Chapter 1 16 split thickness skin grafts both with and without a dermatome use [24,25] to reduce soft tissue depth overlying the implanting area. Over time the approach now focuses on tissue preservation avoiding the possible complications caused by skin flap necrosis [26,27] and thus reducing skin complications [28]. Linear incision techniques have been shown to have a faster healing time and to inflict less pain than dermatome techniques [29,30]. Currently the use of tissue preservation techniques is reported to have the best soft tissue outcomes [31]. Oticon introduced minimally invasive Ponto Surgery (MIPS) which has been shown to have comparable soft tissue outcomes to linear incision techniques [32,33,34] and reduced tissue reaction in some centres to 4.5%, [35] however others have reported fixture failure rate of up to 35% [36]. Figure 2. Components of a percutaneous bone conduction hearing device: comprise of implantable titanium screw, skin penetrating abutment and sound processor. Direct contact with the temporal bone creates two immediate benefits: firstly, better audiological results in both sound field thresholds and speech recognition. Secondly the power of the processor can be increased without complications of migration or significant skin irritation. Limitations of BAHI include peri-abutment soft tissue reactions and fixture loss through either trauma or failed osseointegration, both of which are demonstrated to be higher in paediatric populations [37,38]. Soft tissue reaction is classically monitored and described by the application of the Holgers score (0-4) [39] which shows a wide variation in incidence depending on the surgical technique utilised, the abutment used for mounting the processor and finally subjective reporting by clinicians.
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