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Results of Baha® implantation using a small horizontal incision
AM ER IC AN JOUR NA L OF OTOLARY NG OLOG Y –H EA D A N D N E CK ME D I CI N E AN D SUR G E RY 3 4 ( 2 0 13 ) 64 1–6 4 5
Available online at www.sciencedirect.com
ScienceDirect www.elsevier.com/locate/amjoto
Results of Baha® implantation using a small horizontal incision☆ Jason A. Brant, MD⁎, David Gudis, MD, Michael J. Ruckenstein, MD Department of Otorhinolaryngology-Head and Neck Surgery, Hospitals of the University of Pennsylvania, Philadelphia, PA, USA
ARTI CLE I NFO
A BS TRACT
Article history:
Purpose: Techniques for Baha® implantation continue to evolve. The Weber technique,
Received 2 July 2013
utilizing a 1.5 cm horizontal incision for Baha® implantation is evaluated. Methods: Retrospective review of patients undergoing Baha® implantation by a single surgeon over three years. Results: 33 Baha®s implanted in 30 patients. Fourteen used an Inverted J (IJ) incision with an anteriorly-based skin-flap, 13 with the Weber technique (W). Five were not included as other techniques were used. Demographics and weeks to activation (14.58 vs 13.4, p = 0.12) were similar. There were no differences in the number of patients with minor complications (5 vs 2, p = 0.22) or number of minor complications (20 vs 4, p = 0.09). One patient in the IJ Group required operative revision for overgrowth. There were no infections in the IJ Group, and one requiring oral antibiotics in the W Group. Follow-up was longer in the IJ Group (41 vs 13 weeks, p = 0.016), no complications occurred after 14 weeks post-op. Mean operative times were similar (43 vs 39 min, p = 0.59). There were no cases of skin flap necrosis in either group. Conclusion: A small incision for Baha® implantation proved as effective, without increased complications as a skin-flap based technique. © 2013 Elsevier Inc. All rights reserved.
1.
Introduction
The Bone anchored hearing aid (Baha®) implant offers a highly beneficial option for the rehabilitation of patients with conductive or unilateral sensorineural hearing loss. Since its inception, the surgical technique has been modified to minimize disruption of the soft tissue, surgical times, and post-operative complications. Original implantation techniques involved the utilization of full or partial thickness skin grafts and considerable soft tissue dissection [1]. The postoperative course of a significant number of these patients
was marred by graft loss or skin reaction [1]. More recently, vertical or curved-vertical incisions measuring 4–5 cm have become popular [2,3]. We present the results of a truly minimally invasive technique originally proposed by Peter Weber [4]. This technique, performed under local anesthesia, involves making a small (1.5 cm) horizontal incision, minimal undermining or resection of surrounding soft tissue, and a simple two-suture closure. We present data comparing the Weber technique with a more traditional technique in terms of surgical time, major and minor complications, and failure rate.
☆
Presented as a poster at: The 12th Annual Conference on Cochlear Implants. Baltimore, MD. May, 2012. ⁎ Corresponding author. Philadelphia, PA 19104. Tel.: + 1 215 847 4444; fax: +1 215 662 4515. E-mail address: [email protected] (J.A. Brant).
0196-0709/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.amjoto.2013.07.005
642
AM ER IC AN JOUR NA L OF OTOLARY NG OLOG Y –H EA D A N D N E CK ME D I CI NE AN D SUR G E RY 3 4 ( 2 0 13 ) 64 1–6 4 5
Fig. 1 – Cartoon depictions of various Baha® implantation techniques. (A) Original technique utilizing full thickness skin graft from the post-auricular crease. (B) Anteriorly based full thickness skin graft. (C) Split-thickness skin graft.
2.
Materials and methods
A retrospective chart review was performed of all Baha® implantations by a single surgeon (MR) over a three-year period. This time period included patients in whom the implant was performed using an inverted J incision, and those performed with the new Weber technique (described below). Demographics, infection rate, time to activation, operative time, and subsequent procedures were included in the analysis. Demographics, operative time, time to activation, and follow up time were compared using a t-test, the Fisher’s exact test was used for complications.
Operative techniques Both techniques were performed under local anesthesia with or without sedation in an outpatient surgical center. The site of the implant was marked 5 to 6 cm posteriosuperior to the EAC and an area of the surrounding scalp was shaved and prepped in standard sterile fashion. Local anesthetic was administered to areas of proposed incision and dissection. For the ‘inverted-J’ technique a curvilinear incision was carried to the level of the periosteum to create an anteriorly based skin flap with approximately 2 cm of tissue between the incision and the implant site (Similar to Fig. 1B). The skin flap was thinned and the subcutaneous tissues removed. The periosteum was then removed 4 mm surrounding the implant site and the titanium implant was
Fig. 2 – Cartoon depictions of Baha® implantation techniques with limited soft tissue dissection. (A) Vertical incision. (B) Weber technique.
drilled into place in the traditional fashion. A punch was used to create a defect in the skin flap where the abutment was passed through. The skin was then closed in standard fashion with absorbable sutures and petroleum gauze was packed around the abutment and held in place by a plastic cap that was sutured into place. All patients received a 6 mm abutment. For the Weber technique a 1.5 cm horizontal incision was made through the skin and subcutaneous tissue to the periosteum centered on the implant site (Fig. 2B). The surrounding soft tissue and muscle were removed approximately 1 cm circumferentially (Fig. 3A). The extent of soft tissue removal depended on the thickness of the scalp; patients with thicker skin required more extensive removal. The periosteum was then removed 4 mm surrounding the implant site and the titanium implant was drilled into place in the traditional fashion. The abutment was installed and the skin closed around it with absorbable sutures (Fig. 3B). Petroleum gauze and plastic cap were applied as described above (Fig. 3C). Originally a 6 mm abutment was used, however this has been replaced with a 9 mm abutment to help prevent skin overgrowth.
3.
Results
Thirty-three implants were performed in 30 patients over 31 months. There were two re-implantations for implant extrusion. Fourteen patients underwent fourteen implantations with the Inverted-J (IJ) technique, and thirteen patients underwent 14 implantations with the Weber technique (W). One patient in the latter group had the initial implantation aborted for failure of the implant to seat properly. The implantation was repeated using the same technique. This patient is treated as a single implantation for all statistical analysis, and the aborted procedure was not included. A second patient in this group had the implantation aborted secondary to thin bone resulting from a chronic rheumatoid condition. Three other patients had vertical incisions, and two underwent split thickness skin grafting. One of the implant extrusions was in these patients and was not included in the analysis. The other extrusion was in a patient who originally had an IJ incision, but was revised with a W incision. All results are shown in Table 1.
AM ER IC AN JOUR NA L OF OTOLARY NG OLOG Y –H EA D A N D N E CK ME D I CI N E AN D SUR G E RY 3 4 ( 2 0 13 ) 64 1–6 4 5
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Fig. 3 – Photographs of Weber technique. (A) Exposure of temporal bone through limited incision. (B) Abutment in place and skin sutured around it. (C) Plastic cap sutured in place at end of operation.
There was no significant difference in the age of the patients (51.3 vs 50.5, p = 0.63) or time in weeks to activation (14.58 vs 13.4, p = 0.12) for the IJ and W groups, respectively. One patient in the IJ group with a 6 mm abutment had activation delayed by 4 weeks due to skin hypertrophy. Activation was achieved after changing to a 9 mm abutment. The male to female ratio was 6:8 for the IJ group and 5:8 for the W group. In the IJ group, 5 patients required a total of 7 skin excisions and 13 steroid injections for skin overgrowth, while in the W group, 2 patients required a total of 3 skin excisions and 1 steroid injection. These complications were grouped as ‘minor complications’. There was no statistical difference in the number of patients experiencing minor complications, p = 0.26 or in the number of complications in each group, p = 0.10. One patient in the IJ group and no patients in the W group required operative revision for overgrowth, defined as a major complication, p = 0.54. Seven patients in the IJ group, and one patient in the W group required at least one round of topical steroids (p = 0.028). All patients requiring topical steroids in the IJ group had 6 mm abutments, and the one patient in the W group had a 9 mm abutment. The worst Holgers score in either group was 1, which was observed by two patients in each group (14.3% and 16.7%, p = 0.64), with one additional patient in the W group requiring oral antibiotics for an infectious cellulitis (p = 0.46). Although the followup was significantly longer in the IJ group (41 +/− 19 weeks vs 13 +/− 4 weeks, p = 0.016), no incidences of skin overgrowth requiring treatment occurred after 14 weeks post-op in these
patients. There were no cases of necrosis of the skin flaps in either group. All but one patient in the IJ group had a 6 mm abutment placed at the time of surgery; the other had a 9 mm abutment. This implant failed to osseointegrate and was re-implanted using the W technique. Two patients had their 6 mm changed to a 9 mm abutment at 4 and 18 months postop due to skin overgrowth. Eleven of the twelve implantations in the Weber group used 9 mm abutments. There were no cases of failed implantation in the W group, and the one patient with a 6 mm abutment did not experience any complications, minor or major. Operative time was available for all 14 procedures in the IJ group and 10 of the 12 procedures in the W group. The mean operative times were 43 +/− 12 min (range 29 to 66), and 39 +/− 21 min (range 15 to 88) for the IJ and W group respectively. This difference was not significantly different between the two groups with a p value of 0.59. Excluding a single outlier in the W group where the operative time was 88 min the mean becomes 34 +/− 12 min for the W group with a p value of 0.09 for the difference in operative times between groups.
4.
Discussion
Bone anchored hearing aids utilize osseointegration of a titanium implant in the temporal bone to provide vibratory
Table 1 – Results of Inverted J versus Weber techniques. Incision
N Age M:F Time to Activation (weeks) Topical Steroids Pts with minor complication a Total minor complications Pts with major complication b OR time (min) Extrusion Local Infection a b
Inverted J
Weber
Curvilinear–anterior skin flap
1.5 cm horizontal
14 51.3 6:8 14.58 7 5 20 1 43 +/− 12 1 0
12 50.5 5:7 13.4 1 2 4 0 39 +/− 21 0 1
Minor complications defined as skin excision or steroid injection performed in the office. Major complications defined as any complication requiring return to the operating room, excluding implant extrusion.
P value
0.49 0.63 0.12 0.028 0.26 0.10 0.54 0.59 0.52 0.46
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AM ER IC AN JOUR NA L OF OTOLARY NG OLOG Y –H EA D A N D N E CK ME D I CI NE AN D SUR G E RY 3 4 ( 2 0 13 ) 64 1–6 4 5
stimulation to the cochlea for patients with hearing loss. A percutaneous abutment secured to the implant acts to hold the sound processor in place, and to transfer mechanical energy from the sound processor through the implant to the temporal bone. The utilization of a titanium implant in the cortex of the temporal bone has remained relatively unchanged, however the method for addressing the surrounding soft tissue has evolved significantly. No consensus on best technique has been reached. Implantation of a bone anchored hearing aid was first performed in 1977 by Tjellstrom et al. as a two-staged procedure where the skin and soft tissue over the implant site were removed, the periosteum elevated and the implant drilled into the temporal bone. The soft tissue defect was repaired using a full thickness skin graft from the postauricular crease. Several months later, when the implant had undergone osseointegration, an area of the skin graft was removed over the implant site and the abutment was installed (Fig. 1A). This method was complicated by partial necrosis rates of 15% and total necrosis rates of 0.9% [1,5]. The two-stage procedure was later combined to a single stage where the abutment was installed in the implant at the time of the original surgery. The technique was later modified to utilize an anteriorly based skin flap in place of the free skin graft (Fig. 1B). The skin flap was thinned to reduce tissue bulk and remove hair follicles. Partial and total necrosis rates were decreased to 9.8% and 0.6%, respectively, however results were variable and the procedure remained time consuming [1,5–7]. A dermatome that could be attached to the drill already used for implantation was introduced in 2001. This facilitated the use of split-thickness skin grafts (STSG) to be taken from the surgical site before the underlying soft tissue was removed in a manner similar to previous methods (Fig. 1C) [1]. The implant was then drilled into place and the abutment installed. The area was covered with the skin graft with a defect created using a skin punch for the abutment to pass through. A novel approach was introduced in the 1990’s utilizing a curvilinear incision closed around the protruding abutment which was further refined in 2007 by Bovo et al. This technique involved a 4 to 5 cm vertical incision made 5.5 cm posteriosuperior to the external auditory canal (Fig. 2A). An area of periosteum and subcutaneous tissue was removed in a circle approximately 4 cm in diameter surrounding the implant site. The skin was then closed around the abutment and covered with petroleum gauze and a protective cap [2,8,9]. Skin overgrowth and irritation remain common complications for all techniques [3], and for procedures utilizing STSG partial or total necrosis of the graft is common [10]. The technique described in this study extends the trend towards limited incision and soft tissue dissection. Theoretical benefits of the skin graft technique include removal of all sebaceous glands and hair follicles decreasing the probability of infection and inflammation, and tighter adherence of the skin to the periosteum. It has been proposed that skin overgrowth is a reaction to inflammation caused by movement relative to the abutment, and an STSG directly overlying the periosteum would reduce this move-
ment [1]. However, techniques utilizing an STSG have partial or total graft loss of up to ten percent while continuing to experience high rates of skin overgrowth [10,11]. A direct comparison of skin inflammation between a STSG technique and a skin flap technique failed to show statistical difference between the two groups, although a trend towards improvement in the STSG group was noted [12]. Such techniques additionally have increased cosmetic impact and operative complexity. Techniques involving closure of the incision directly around the abutment were developed to avoid the problems of reduced blood flow in pedicled flaps leading to necrosis [2]. In this method the blood supply is maintained from both directions allowing the periosteum to be removed along with subcutaneous tissues, and reducing the probability of flap necrosis. The currently described technique extends this idea with a smaller incision oriented horizontally instead of vertically. Both techniques can be performed quickly without specialized equipment. In this study the follow-up period for the inverted-J technique was significantly longer than for the Weber technique allowing for the possibility of late complications not included in the current analysis. All complications in the inverted-J group occurred within 14 weeks of the primary procedure, and other groups have noted a similar trend of complications occurring early [10]. Others have noted more delayed overgrowth requiring surgical excision, however [3,13]. Over the course of this study the standard abutment size was changed from 6 mm to 9 mm at the time of implantation. This transition coincided with the change in operative techniques. Only one patient from each surgical group was fitted with the abutment size of the other. The longer abutment has been used with success in patients with thick tissues surrounding the implant, and in those where soft tissue overgrowth was a persistent problem [14]. In the present study there were significantly fewer patients requiring topical steroids in the W or 9 mm group than in the IJ or 6 mm group. Because the changes in abutment length and surgical technique coincided, it is not possible to determine which factor caused the change in steroid requirements. The single patient in the IJ group who received a 9 mm abutment initially failed to osseointegrate, however this was not seen in any of the patients in the W group. There were no noted complaints from patients about the longer abutments, but no formal evaluation of patient satisfaction was performed. Although skin irritation remained a common complication in the Weber group of patients, no patients required return to the operating room for revision. Although not reaching statistical significance there was also a decrease in operative time for the new procedure. This method has become the standard procedure for the senior author. Further study is needed to confirm the trends noted with this limited sample size, and to evaluate for long-term complications with the routine use of the 9 mm abutment. As described, the Weber technique uses the smallest skin incision and the least amount of soft tissue dissection of any published method for BAHA implantation. In this series the postoperative complications were comparable to those of an
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anteriorly based skin flap technique used previously, and with published complication rates of several different techniques. Although more patients will have to be evaluated with longer follow-up times to validate this method, the data presented confirm this as a viable technique for BAHA implantation.
REFERENCES
[1] Tjellström A, Granström G. How we do it: frequency of skin necrosis after BAHA surgery. Clin Otolaryngol 2006;31:216–20. [2] Bovo R. Simplified technique without skin flap for the boneanchored hearing aid (BAHA) implant. Acta Otorhinolaryngol Ital 2008;28:252–5. [3] Wilkinson EP, Luxford WM, Slattery WH, et al. Single vertical incision for Baha implant surgery: preliminary results. Otolaryngol Head Neck Surg 2009;140:573–8. [4] Weber P. Minimally invasive approach for Baha surgery, Presented at The Third International Symposium: Bone Conduction Hearing-Craniofacial Osseointegration, Sarasota, Florida, March 23–26, 2011. [5] Tjellström A, Granström G. One-stage procedure to establish osseointegration: a zero to five years follow-up report. J Laryngol Otol 1995;109:593–8.
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[6] Tjellström A. Osseointegrated systems and their application in the head and neck, vol. 3. Adv Otolaryngol Head Neck Surg 1989:39–70. [7] Kohan D, Morris LGT, Romo T. Single-stage BAHA implantation in adults and children: is it safe? Otolaryngol Head Neck Surg 2008;138:662–6. [8] de Wolf MJF, Hol MKS, Huygen PLM, et al. Nijmegen results with application of a bone-anchored hearing aid in children: simplified surgical technique. Ann Otol Rhinol Laryngol 2008;117:805–14. [9] de Wolf MJF, Hol MKS, Huygen PLM, et al. Clinical outcome of the simplified surgical technique for BAHA implantation. Otol Neurotol 2008;29:1100–8. [10] Shirazi MA, Marzo SJ, Leonetti JP. Perioperative complications with the bone-anchored hearing aid. Otolaryngol Head Neck Surg 2006;134:236–9. [11] Badran K, Arya AK, Bunstone D, et al. Long-term complications of bone-anchored hearing aids: a 14-year experience. J Laryngol Otol 2009;123:170–6. [12] Stalfors J, Tjellström A. Skin reactions after BAHA surgery: a comparison between the U-graft technique and the BAHA dermatome. Otol Neurotol 2008;29:1109–14. [13] House JW, Kutz JW. Bone-anchored hearing aids: incidence and management of postoperative complications. Otol Neurotol 2007;28:213–7. [14] Monksfield P, Ho EC, Reid A, et al. Experience with the longer (8.5 mm) abutment for Bone-Anchored Hearing Aid. Otol Neurotol 2009;30:274–6.
Available online at www.sciencedirect.com
ScienceDirect www.elsevier.com/locate/amjoto
Results of Baha® implantation using a small horizontal incision☆ Jason A. Brant, MD⁎, David Gudis, MD, Michael J. Ruckenstein, MD Department of Otorhinolaryngology-Head and Neck Surgery, Hospitals of the University of Pennsylvania, Philadelphia, PA, USA
ARTI CLE I NFO
A BS TRACT
Article history:
Purpose: Techniques for Baha® implantation continue to evolve. The Weber technique,
Received 2 July 2013
utilizing a 1.5 cm horizontal incision for Baha® implantation is evaluated. Methods: Retrospective review of patients undergoing Baha® implantation by a single surgeon over three years. Results: 33 Baha®s implanted in 30 patients. Fourteen used an Inverted J (IJ) incision with an anteriorly-based skin-flap, 13 with the Weber technique (W). Five were not included as other techniques were used. Demographics and weeks to activation (14.58 vs 13.4, p = 0.12) were similar. There were no differences in the number of patients with minor complications (5 vs 2, p = 0.22) or number of minor complications (20 vs 4, p = 0.09). One patient in the IJ Group required operative revision for overgrowth. There were no infections in the IJ Group, and one requiring oral antibiotics in the W Group. Follow-up was longer in the IJ Group (41 vs 13 weeks, p = 0.016), no complications occurred after 14 weeks post-op. Mean operative times were similar (43 vs 39 min, p = 0.59). There were no cases of skin flap necrosis in either group. Conclusion: A small incision for Baha® implantation proved as effective, without increased complications as a skin-flap based technique. © 2013 Elsevier Inc. All rights reserved.
1.
Introduction
The Bone anchored hearing aid (Baha®) implant offers a highly beneficial option for the rehabilitation of patients with conductive or unilateral sensorineural hearing loss. Since its inception, the surgical technique has been modified to minimize disruption of the soft tissue, surgical times, and post-operative complications. Original implantation techniques involved the utilization of full or partial thickness skin grafts and considerable soft tissue dissection [1]. The postoperative course of a significant number of these patients
was marred by graft loss or skin reaction [1]. More recently, vertical or curved-vertical incisions measuring 4–5 cm have become popular [2,3]. We present the results of a truly minimally invasive technique originally proposed by Peter Weber [4]. This technique, performed under local anesthesia, involves making a small (1.5 cm) horizontal incision, minimal undermining or resection of surrounding soft tissue, and a simple two-suture closure. We present data comparing the Weber technique with a more traditional technique in terms of surgical time, major and minor complications, and failure rate.
☆
Presented as a poster at: The 12th Annual Conference on Cochlear Implants. Baltimore, MD. May, 2012. ⁎ Corresponding author. Philadelphia, PA 19104. Tel.: + 1 215 847 4444; fax: +1 215 662 4515. E-mail address: [email protected] (J.A. Brant).
0196-0709/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.amjoto.2013.07.005
642
AM ER IC AN JOUR NA L OF OTOLARY NG OLOG Y –H EA D A N D N E CK ME D I CI NE AN D SUR G E RY 3 4 ( 2 0 13 ) 64 1–6 4 5
Fig. 1 – Cartoon depictions of various Baha® implantation techniques. (A) Original technique utilizing full thickness skin graft from the post-auricular crease. (B) Anteriorly based full thickness skin graft. (C) Split-thickness skin graft.
2.
Materials and methods
A retrospective chart review was performed of all Baha® implantations by a single surgeon (MR) over a three-year period. This time period included patients in whom the implant was performed using an inverted J incision, and those performed with the new Weber technique (described below). Demographics, infection rate, time to activation, operative time, and subsequent procedures were included in the analysis. Demographics, operative time, time to activation, and follow up time were compared using a t-test, the Fisher’s exact test was used for complications.
Operative techniques Both techniques were performed under local anesthesia with or without sedation in an outpatient surgical center. The site of the implant was marked 5 to 6 cm posteriosuperior to the EAC and an area of the surrounding scalp was shaved and prepped in standard sterile fashion. Local anesthetic was administered to areas of proposed incision and dissection. For the ‘inverted-J’ technique a curvilinear incision was carried to the level of the periosteum to create an anteriorly based skin flap with approximately 2 cm of tissue between the incision and the implant site (Similar to Fig. 1B). The skin flap was thinned and the subcutaneous tissues removed. The periosteum was then removed 4 mm surrounding the implant site and the titanium implant was
Fig. 2 – Cartoon depictions of Baha® implantation techniques with limited soft tissue dissection. (A) Vertical incision. (B) Weber technique.
drilled into place in the traditional fashion. A punch was used to create a defect in the skin flap where the abutment was passed through. The skin was then closed in standard fashion with absorbable sutures and petroleum gauze was packed around the abutment and held in place by a plastic cap that was sutured into place. All patients received a 6 mm abutment. For the Weber technique a 1.5 cm horizontal incision was made through the skin and subcutaneous tissue to the periosteum centered on the implant site (Fig. 2B). The surrounding soft tissue and muscle were removed approximately 1 cm circumferentially (Fig. 3A). The extent of soft tissue removal depended on the thickness of the scalp; patients with thicker skin required more extensive removal. The periosteum was then removed 4 mm surrounding the implant site and the titanium implant was drilled into place in the traditional fashion. The abutment was installed and the skin closed around it with absorbable sutures (Fig. 3B). Petroleum gauze and plastic cap were applied as described above (Fig. 3C). Originally a 6 mm abutment was used, however this has been replaced with a 9 mm abutment to help prevent skin overgrowth.
3.
Results
Thirty-three implants were performed in 30 patients over 31 months. There were two re-implantations for implant extrusion. Fourteen patients underwent fourteen implantations with the Inverted-J (IJ) technique, and thirteen patients underwent 14 implantations with the Weber technique (W). One patient in the latter group had the initial implantation aborted for failure of the implant to seat properly. The implantation was repeated using the same technique. This patient is treated as a single implantation for all statistical analysis, and the aborted procedure was not included. A second patient in this group had the implantation aborted secondary to thin bone resulting from a chronic rheumatoid condition. Three other patients had vertical incisions, and two underwent split thickness skin grafting. One of the implant extrusions was in these patients and was not included in the analysis. The other extrusion was in a patient who originally had an IJ incision, but was revised with a W incision. All results are shown in Table 1.
AM ER IC AN JOUR NA L OF OTOLARY NG OLOG Y –H EA D A N D N E CK ME D I CI N E AN D SUR G E RY 3 4 ( 2 0 13 ) 64 1–6 4 5
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Fig. 3 – Photographs of Weber technique. (A) Exposure of temporal bone through limited incision. (B) Abutment in place and skin sutured around it. (C) Plastic cap sutured in place at end of operation.
There was no significant difference in the age of the patients (51.3 vs 50.5, p = 0.63) or time in weeks to activation (14.58 vs 13.4, p = 0.12) for the IJ and W groups, respectively. One patient in the IJ group with a 6 mm abutment had activation delayed by 4 weeks due to skin hypertrophy. Activation was achieved after changing to a 9 mm abutment. The male to female ratio was 6:8 for the IJ group and 5:8 for the W group. In the IJ group, 5 patients required a total of 7 skin excisions and 13 steroid injections for skin overgrowth, while in the W group, 2 patients required a total of 3 skin excisions and 1 steroid injection. These complications were grouped as ‘minor complications’. There was no statistical difference in the number of patients experiencing minor complications, p = 0.26 or in the number of complications in each group, p = 0.10. One patient in the IJ group and no patients in the W group required operative revision for overgrowth, defined as a major complication, p = 0.54. Seven patients in the IJ group, and one patient in the W group required at least one round of topical steroids (p = 0.028). All patients requiring topical steroids in the IJ group had 6 mm abutments, and the one patient in the W group had a 9 mm abutment. The worst Holgers score in either group was 1, which was observed by two patients in each group (14.3% and 16.7%, p = 0.64), with one additional patient in the W group requiring oral antibiotics for an infectious cellulitis (p = 0.46). Although the followup was significantly longer in the IJ group (41 +/− 19 weeks vs 13 +/− 4 weeks, p = 0.016), no incidences of skin overgrowth requiring treatment occurred after 14 weeks post-op in these
patients. There were no cases of necrosis of the skin flaps in either group. All but one patient in the IJ group had a 6 mm abutment placed at the time of surgery; the other had a 9 mm abutment. This implant failed to osseointegrate and was re-implanted using the W technique. Two patients had their 6 mm changed to a 9 mm abutment at 4 and 18 months postop due to skin overgrowth. Eleven of the twelve implantations in the Weber group used 9 mm abutments. There were no cases of failed implantation in the W group, and the one patient with a 6 mm abutment did not experience any complications, minor or major. Operative time was available for all 14 procedures in the IJ group and 10 of the 12 procedures in the W group. The mean operative times were 43 +/− 12 min (range 29 to 66), and 39 +/− 21 min (range 15 to 88) for the IJ and W group respectively. This difference was not significantly different between the two groups with a p value of 0.59. Excluding a single outlier in the W group where the operative time was 88 min the mean becomes 34 +/− 12 min for the W group with a p value of 0.09 for the difference in operative times between groups.
4.
Discussion
Bone anchored hearing aids utilize osseointegration of a titanium implant in the temporal bone to provide vibratory
Table 1 – Results of Inverted J versus Weber techniques. Incision
N Age M:F Time to Activation (weeks) Topical Steroids Pts with minor complication a Total minor complications Pts with major complication b OR time (min) Extrusion Local Infection a b
Inverted J
Weber
Curvilinear–anterior skin flap
1.5 cm horizontal
14 51.3 6:8 14.58 7 5 20 1 43 +/− 12 1 0
12 50.5 5:7 13.4 1 2 4 0 39 +/− 21 0 1
Minor complications defined as skin excision or steroid injection performed in the office. Major complications defined as any complication requiring return to the operating room, excluding implant extrusion.
P value
0.49 0.63 0.12 0.028 0.26 0.10 0.54 0.59 0.52 0.46
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stimulation to the cochlea for patients with hearing loss. A percutaneous abutment secured to the implant acts to hold the sound processor in place, and to transfer mechanical energy from the sound processor through the implant to the temporal bone. The utilization of a titanium implant in the cortex of the temporal bone has remained relatively unchanged, however the method for addressing the surrounding soft tissue has evolved significantly. No consensus on best technique has been reached. Implantation of a bone anchored hearing aid was first performed in 1977 by Tjellstrom et al. as a two-staged procedure where the skin and soft tissue over the implant site were removed, the periosteum elevated and the implant drilled into the temporal bone. The soft tissue defect was repaired using a full thickness skin graft from the postauricular crease. Several months later, when the implant had undergone osseointegration, an area of the skin graft was removed over the implant site and the abutment was installed (Fig. 1A). This method was complicated by partial necrosis rates of 15% and total necrosis rates of 0.9% [1,5]. The two-stage procedure was later combined to a single stage where the abutment was installed in the implant at the time of the original surgery. The technique was later modified to utilize an anteriorly based skin flap in place of the free skin graft (Fig. 1B). The skin flap was thinned to reduce tissue bulk and remove hair follicles. Partial and total necrosis rates were decreased to 9.8% and 0.6%, respectively, however results were variable and the procedure remained time consuming [1,5–7]. A dermatome that could be attached to the drill already used for implantation was introduced in 2001. This facilitated the use of split-thickness skin grafts (STSG) to be taken from the surgical site before the underlying soft tissue was removed in a manner similar to previous methods (Fig. 1C) [1]. The implant was then drilled into place and the abutment installed. The area was covered with the skin graft with a defect created using a skin punch for the abutment to pass through. A novel approach was introduced in the 1990’s utilizing a curvilinear incision closed around the protruding abutment which was further refined in 2007 by Bovo et al. This technique involved a 4 to 5 cm vertical incision made 5.5 cm posteriosuperior to the external auditory canal (Fig. 2A). An area of periosteum and subcutaneous tissue was removed in a circle approximately 4 cm in diameter surrounding the implant site. The skin was then closed around the abutment and covered with petroleum gauze and a protective cap [2,8,9]. Skin overgrowth and irritation remain common complications for all techniques [3], and for procedures utilizing STSG partial or total necrosis of the graft is common [10]. The technique described in this study extends the trend towards limited incision and soft tissue dissection. Theoretical benefits of the skin graft technique include removal of all sebaceous glands and hair follicles decreasing the probability of infection and inflammation, and tighter adherence of the skin to the periosteum. It has been proposed that skin overgrowth is a reaction to inflammation caused by movement relative to the abutment, and an STSG directly overlying the periosteum would reduce this move-
ment [1]. However, techniques utilizing an STSG have partial or total graft loss of up to ten percent while continuing to experience high rates of skin overgrowth [10,11]. A direct comparison of skin inflammation between a STSG technique and a skin flap technique failed to show statistical difference between the two groups, although a trend towards improvement in the STSG group was noted [12]. Such techniques additionally have increased cosmetic impact and operative complexity. Techniques involving closure of the incision directly around the abutment were developed to avoid the problems of reduced blood flow in pedicled flaps leading to necrosis [2]. In this method the blood supply is maintained from both directions allowing the periosteum to be removed along with subcutaneous tissues, and reducing the probability of flap necrosis. The currently described technique extends this idea with a smaller incision oriented horizontally instead of vertically. Both techniques can be performed quickly without specialized equipment. In this study the follow-up period for the inverted-J technique was significantly longer than for the Weber technique allowing for the possibility of late complications not included in the current analysis. All complications in the inverted-J group occurred within 14 weeks of the primary procedure, and other groups have noted a similar trend of complications occurring early [10]. Others have noted more delayed overgrowth requiring surgical excision, however [3,13]. Over the course of this study the standard abutment size was changed from 6 mm to 9 mm at the time of implantation. This transition coincided with the change in operative techniques. Only one patient from each surgical group was fitted with the abutment size of the other. The longer abutment has been used with success in patients with thick tissues surrounding the implant, and in those where soft tissue overgrowth was a persistent problem [14]. In the present study there were significantly fewer patients requiring topical steroids in the W or 9 mm group than in the IJ or 6 mm group. Because the changes in abutment length and surgical technique coincided, it is not possible to determine which factor caused the change in steroid requirements. The single patient in the IJ group who received a 9 mm abutment initially failed to osseointegrate, however this was not seen in any of the patients in the W group. There were no noted complaints from patients about the longer abutments, but no formal evaluation of patient satisfaction was performed. Although skin irritation remained a common complication in the Weber group of patients, no patients required return to the operating room for revision. Although not reaching statistical significance there was also a decrease in operative time for the new procedure. This method has become the standard procedure for the senior author. Further study is needed to confirm the trends noted with this limited sample size, and to evaluate for long-term complications with the routine use of the 9 mm abutment. As described, the Weber technique uses the smallest skin incision and the least amount of soft tissue dissection of any published method for BAHA implantation. In this series the postoperative complications were comparable to those of an
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anteriorly based skin flap technique used previously, and with published complication rates of several different techniques. Although more patients will have to be evaluated with longer follow-up times to validate this method, the data presented confirm this as a viable technique for BAHA implantation.
REFERENCES
[1] Tjellström A, Granström G. How we do it: frequency of skin necrosis after BAHA surgery. Clin Otolaryngol 2006;31:216–20. [2] Bovo R. Simplified technique without skin flap for the boneanchored hearing aid (BAHA) implant. Acta Otorhinolaryngol Ital 2008;28:252–5. [3] Wilkinson EP, Luxford WM, Slattery WH, et al. Single vertical incision for Baha implant surgery: preliminary results. Otolaryngol Head Neck Surg 2009;140:573–8. [4] Weber P. Minimally invasive approach for Baha surgery, Presented at The Third International Symposium: Bone Conduction Hearing-Craniofacial Osseointegration, Sarasota, Florida, March 23–26, 2011. [5] Tjellström A, Granström G. One-stage procedure to establish osseointegration: a zero to five years follow-up report. J Laryngol Otol 1995;109:593–8.
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[6] Tjellström A. Osseointegrated systems and their application in the head and neck, vol. 3. Adv Otolaryngol Head Neck Surg 1989:39–70. [7] Kohan D, Morris LGT, Romo T. Single-stage BAHA implantation in adults and children: is it safe? Otolaryngol Head Neck Surg 2008;138:662–6. [8] de Wolf MJF, Hol MKS, Huygen PLM, et al. Nijmegen results with application of a bone-anchored hearing aid in children: simplified surgical technique. Ann Otol Rhinol Laryngol 2008;117:805–14. [9] de Wolf MJF, Hol MKS, Huygen PLM, et al. Clinical outcome of the simplified surgical technique for BAHA implantation. Otol Neurotol 2008;29:1100–8. [10] Shirazi MA, Marzo SJ, Leonetti JP. Perioperative complications with the bone-anchored hearing aid. Otolaryngol Head Neck Surg 2006;134:236–9. [11] Badran K, Arya AK, Bunstone D, et al. Long-term complications of bone-anchored hearing aids: a 14-year experience. J Laryngol Otol 2009;123:170–6. [12] Stalfors J, Tjellström A. Skin reactions after BAHA surgery: a comparison between the U-graft technique and the BAHA dermatome. Otol Neurotol 2008;29:1109–14. [13] House JW, Kutz JW. Bone-anchored hearing aids: incidence and management of postoperative complications. Otol Neurotol 2007;28:213–7. [14] Monksfield P, Ho EC, Reid A, et al. Experience with the longer (8.5 mm) abutment for Bone-Anchored Hearing Aid. Otol Neurotol 2009;30:274–6.