Discussion

Bone-anchored hearing aid implants were introduced in 1977 by Tjellström and colleagues (as cited in Holgers et al.Reference Holgers, Tjellström, Bjursten and Erlandsson¹). Since then, BAHAs have become a well-established tool for satisfactory management of several conditions associated with hearing loss. The BAHA system comprises a speech receptor and processor, which processes the received noise and transmits it as vibratory energy to the abutment. This abutment is attached to the titanium implant, which in turn is embedded in the mastoid bone.Reference Hobson, Roper, Andrew, Rothera, Hill and Green²

The surgical procedure for BAHA implantation is safe, and the majority of adverse reactions are local reactions and are related to the implant itself. Most of the complications associated with BAHA implants concern the subcutaneous tissue reduction and the consequent skin reaction.Reference Husseman, Szudek, Monksfield, Power, O'Leary and Briggs³ The most common complications reported in the literature are skin overgrowth and infection of the metallic implant site.Reference Hobson, Roper, Andrew, Rothera, Hill and Green² Unsuccessful skin grafting, cellulitis, granulation, eczematous dermatitis, hypertrophic scarring and keloid formation, and even loss of the implant, can also occur.Reference Shirazi, Marzo and Leonetti^4–Reference Gillett, Fairley, Chandrashaker, Bean and Gonzalez⁸ The incidence of skin reaction varies between 5 and 50 per cent in different studies, depending on the surgical technique used and the method of inflammation classification.Reference Granström and Tjellström^9–Reference Tamarit Conejeros, Dalmau Galofre, Murcia Puchades, Pons Rocher, Fernández Martínez and Estrems Navas¹²

The Holgers' classification is used to describe peri-abutment skin reactions.Reference Holgers, Tjellström, Bjursten and Erlandsson¹ The skin reactions are graded as follows: 0 = no tissue irritation, 1 = small erythema, 2 = erythema and humidity, 3 = granulation, and 4 = infection leading to removal of the abutment. The majority of cases referred for complications can be conservatively treated, although 1 to 2 per cent of patients need surgical intervention, and, in some cases, removal of the implant is required. Recent studies have shown that the application of a corticosteroid gel can be effective at reducing the occurrence of skin reaction.Reference Falcone, Kaylie, Labadie and Haynes¹³ This achieves better results in cases with Holgers' grade 1 and 2 skin reactions. In Holgers' grade 3 cases, resection of the granulation tissue is often indicated. In Holgers' grade 4 cases, in addition to resection of the granulation tissue, replacement of the abutment with a longer one is recommended.Reference Holgers, Tjellström, Bjursten and Erlandsson¹

In our patient, the episodes of skin reaction became very frequent and he was unable to use his BAHA for 2 to 3 days in a week. The response to the topical treatment was poor. Furthermore, the child had moved to a distant location with limited access to clinical care. We opted for surgical treatment using a Z-plasty technique for management of the skin complications.

The classic Z-plasty technique involves a central incision and two peripheral incisions made in a ‘Z’ shape, creating two skin flaps of identical size with a triangular shape. This technique allows the surgeon to change the direction of the scar, interrupt the linear component of the scar and lengthen its cicatricial contracture.Reference Frodel¹⁴ In the present case, the Z-plasty technique enabled removal of the granulation tissue at the edges of the incision from the surroundings of the implant, therefore ensuring that only disease-free skin would be in contact with the implant after the procedure.

Several BAHA implantation surgical techniques have been described. These range from a skin flap creation with a surgical dermatome (a technique currently proscribed given the high levels of adverse reactions),Reference Van Rompaey, Claes, Verstraeten, van Dinther, Zarowski and Offeciers¹⁵ to the technique of simple incision with subcutaneous tissue reductionReference de Wolf, Hol, Huygen, Mylanus and Cremers^10, Reference de Wolf, Hol, Huygen, Mylanus and Cremers¹⁶ and recently without subcutaneous tissue reduction.Reference Hultcrantz¹⁷ A recent clinical trial by Hultcrantz showed that a BAHA implantation technique using simple incision methods, without subcutaneous tissue trimming, was associated with reduced surgical time, faster wound healing and no complications in the studied population, when compared to the conventional dermatome technique and subcutaneous tissue reduction.Reference Hultcrantz¹⁷

New techniques aiming to reduce skin reactions focus on the use of longer abutments (8.5 mm)Reference Pelosi and Chandrasekhar¹⁸ and hydroxyapatite-coated abutments.Reference Larsson, Wigren, Andersson, Ekeroth, Flynn and Nannmark¹⁹ In our department, after a discussion at the Osseo workshop in Newcastle, UK, in June 2013, we abandoned the technique of subcutaneous tissue resection. Instead, we now perform linear incision with local removal lateral to the incision using a 0.6 mm punch. While the hydroxyapatite-coated abutments await the Brazilian National Health Surveillance Agency (‘ANVISA’) licence, we have been using the 8.5 mm abutments in adults and older children, and the 4.5 mm abutments in younger children. After adopting this technique, we observed the results described in the literature in our patients. These gains included reduced surgery time, the increased use of local anaesthetic and sedation (rather than general anaesthetic), the absence of pain or loss of sensation, and the absence of skin complications.Reference Larsson, Wigren, Andersson, Ekeroth, Flynn and Nannmark¹⁹