Ir J Med Sci DOI 10.1007/s11845-014-1151-y
ORIGINAL ARTICLE
Soft tissue reactions in patients with bone anchored hearing aids J. Rebol
Received: 4 February 2014 / Accepted: 21 May 2014 Ó Royal Academy of Medicine in Ireland 2014
Abstract Aims To establish the incidence and correlation between the degree of soft tissue reaction and the body mass index (BMI) according to age and gender after a bone anchored hearing aid (BAHA) implant. Methods We did a 1–9-year follow-up for the all the patients who underwent surgery in our department with BAHA implant system. Soft tissue reactions were classified in accordance with the Holgers classification on regular patient visits. BMI was calculated for each patient, and changes were recorded at least once a year. Results 47 patients were evaluated. 58 % were operated on for chronic otitis with mixed or conductive hearing loss; 20 % had unilateral or bilateral atresia and 16 % had single sided deafness (SSD); other indications were otosclerosis and syndromic patients. The grade of Holgers classification significantly correlated at a 0.001 level with BMI (Spearmans rho 0.452). Holgers grade also differed significantly between the sexes–skin reactions in females were less frequent. An ANOVA test did not reveal any statistical difference between patients with dissimilar indications for BAHA. Conclusion If performed carefully, BAHA surgery produces a favorable outcome. The Holgers grade may change as time passes. If skin reactions appear, they can be treated through local or systemic therapy, and they may turn into a normal grade. Adipose patients should be treated with special care because they are more prone to soft tissue reactions.
J. Rebol (&) Maribor University Hospital, Ljubljanska 5, 2000 Maribor, Slovenia e-mail: [email protected]
Keywords Bone anchored hearing aid Skin reaction Holgers classification Body mass index
Introduction The bone anchored hearing aid (BAHA) system consists of bone anchored titanium implant, abutment and processor, which is attached to the abutment (Fig. 1). It is a percutaneous device and was first applied to patients with significant bilateral conductive or mixed hearing loss in which middle ear surgery can not bring any improvement and can not wear conventional hearing aids. Because of its success, indications have been extended. Audiological indications now include conductive and mixed hearing loss and single side deafness. Medical indications include radically operated patients with chronic otitis, atresia of external ear canal, patients who loose their hearing in vestibular schwannomma surgery and otosclerosis [1]. The first BAHA operation was accomplished in 1977; in 1989, the standard two-stage procedure was exchanged for a single procedure that already concerned itself with how skin should react in the immediate postoperative period and in the long run. During the early years of BAHA surgery, either no or minimum soft tissue thinning was done. Patient follow-up made it clear that skin mobility in relation to the implant involved the risk of adverse tissue reactions. During the 1980s, a hairless skin graft was taken from the retroauricular fold. With this technique, the frequency of partial necrosis was 15.7 % and there was total necrosis in 0.9 %. About that time the application of a free skin graft around the abutment was abandoned. An anteriorly based pedicled flap was added, and it was thinned with a blade. The frequency of partial necrosis was found to be 9.8 % and total necrosis 0.6 %. A specially designed dermatome
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Ir J Med Sci
Fig. 1 BAHA device in place located retroauricularly in patient with microtia and atresia of the external ear canal
was introduced in 2001. The flap width in this technique is 25 mm and its thickness is fixed at 0.6 mm. In addition, all hair follicles have to be removed from the underlying tissue. Only the innermost periost layer is left in a space of 5–7 mm around the coupling. The incidence of minor skin necrosis in Tjellstro¨m’s series was 3.0 % [2] with the dermatome technique. Depending on the BAHA implant center and duration of follow-up, implant loss rates have varied 3.5–17.4 % in adults and 5.3–30 % in children. In a study by de Wolf et al., [3] the total rate of implant loss was 6.5 % in almost 250 patients; 3.6 % was due to osseointegration failure. The authors suggest that one of the advantages of the linear incision technique is the prevention of skin flap necrosis. Soft tissue reactions after BAHA surgery are infrequent, but they do occur. Wazen reported 8.1 % of patients requiring local care for cellulitis, granular dermatitis, pain, neuralgia, and immediate postoperative complications such as bleeding or dehiscence [4]. The probability of losing an implant because of adverse skin reactions is quite low; however, skin reactions, if left untreated, may eventually lead to implant loss or withdrawal. Our clinical impression is that soft tissue complications with BAHA are most common in patients with thick subcutaneous tissue at the implant site. Elevated body mass index (BMI) could be used as a predictor of soft tissue complications. In these patients the use of 8.5 mm abutment could prevent subsequent problems.
Materials and methods All patients were operated in our department. The followup period was between 1 and 9 years. We noted the
123
Fig. 2 BAHA abutment in the same patient as in Fig. 1. Note flat skin with no skin inflammation around the abutment–Holgers grade 0
Fig. 3 Inflammation and skin overgrowth around the abutment– Holgers grade 4
indications for surgery, age, side of the BAHA application; on regular controls, soft tissue reactions around the abutment were noted and categorized according to Holgers classification. The Holgers grading system of postoperative skin irritation is now widely used for describing the state of the skin around the abutment [5, 6]. Grade 0 means no irritation (Fig. 2); grade 1, slight redness; grade 2, red and moist tissue; grade 3, granulation tissue, and grade 4, infection leading to removal of the abutment (Fig. 3). Grades 1–2 can be treated with local therapy, grades 3–4 may require oral antibiotic therapy or even excision of the skin if overgrowth develops. The author performed the dermatome technique on all patients with the appropriate subcutaneous thinning in order to prevent immediate or delayed skin reactions.
Ir J Med Sci
Fig. 4 Percentage of patients with grade 2? of Holgers classification during 9 years observation period
Fig. 5 Holgers grade in 6 patients with 9 years experience
Operations on adult patients were performed using local anesthesia, children and syndromic patients with general anesthesia. During the last 3 years, the BI300 implant [7] has been used in surgery; before that, an implant of a previous generation had been used. Before surgery, pure tone averages for bone and air conduction in the operated ear were calculated at 0.5, 1, 2, and 3 kHz. Body mass index [8] was calculated from the data recorded at the time of surgery. BMI is defined as the individual’s body weight divided by the square of his or her height. The formula universally used in medicine produces a unit of measure of kg/m2. Body mass index groups are defined as underweight if the BMI is less than 18.5 kg/m2, normal 18.5–24.9 kg/m2, overweight 25.0–29.9 kg/m2, or obese greater than 30 kg/m2.
Table 1 Correlation coefficients for BMI (body mass index) BMI Age
0.503
Holgers grade
0.452
In bold-correlation is significant at the 0.001 level (Spearman’s rho coefficient)
Table 2 Differences in age, mean Holgers grade, body mass index (BMI) and air bone gap (ABG) between sexes—men (m), women (w)
Gender
Mean
Std. deviation
M
45.40
18.71
W
43.28
16.81
Age
Holgers grade M
1.27
1.33
W
0.36
0.63
M
27.06
7.11
W
24.32
5.35
BMI
Results Our follow-up covered 15 men and 32 women who had undergone surgery from 2 to 10 years ago. Their average age was 43 years; five patients were younger than 16 years; the youngest was 7 years old and the oldest 72. The indications for the operations were in 55.3 % radically operated chronic otitis, bilateral atresia in 14.9 %, unilateral atresia in 6.3 %, idiopathic single sided deafness in 4.3 %, single sided deafness after vestibular schwannoma removal in 4.2 %, otosclerosis in 4.3 and 2.1 % with Down syndrome and conductive hearing loss. In Fig. 4, the percentage of patients with a Holgers grade of more than or equal to 2 is shown. In our 9-year observation period, the percentage of these patients varied between 6 and 22 %. Seventeen patients had at least 4 years of BAHA experience. Seven of them showed variations of Holgers grade during that time or their Holgers grade was above 0. In the remaining 10 patients, the skin around the BAHA abutment showed no abnormalities. Six of our patients had 9 years of BAHA experience. Holgers grade reached grade 3 in two of them and then
Difference in Holgers grade is statistically significant at 0.001 level In bold-correlation is significant at the 0.001 level (Spearman’s rho coefficient)
ABG (dB) M
40.92
12.76
W
40.20
9.63
returned to grade 0. In one patient, the Holgers grade varied between 0 and 1, and in two patients it remained at 0 the whole time. In the entire patient population, only three reached grade 4, and in one of these patients, we had an implant loss 7 months after surgery caused by osseointegration failure (Fig. 5). The mean values for BMI for men and women were 27.06 and 24.32 kg/m2. In men this index recorded overweight and in women, normal weight. BMI did not correlate with the age of the patients. Holgers grade significantly correlates with BMI at the 0.001 level (Table 1). Both sexes had almost the same age and air bone gap. There was a marked difference between the sexes in Holgers grade, which was higher in males (Table 2). We also looked at Holgers grades in different BAHA indications. Maximal values differed significantly, but the
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Ir J Med Sci
Fig. 6 Holgers grade dynamics. 45.9 % had constantly grade 0, constant grade had 8.1 %, falling grade was observed in 16.2 %, increasing in 10.8 %, increasing then falling in 16.2 % and oscillating in 2.7 %
mean values were much the same. ANOVA test did not show significant differences between the indications. Holgers grade dynamics is shown in the Fig. 6. In 29 % the skin conditions around the implant were unstable (increasing, oscillating or increasing and then falling). The other patients had either constant Holgers grade 0, constant other Holgers grade or falling Holgers grade.
Discussion The percutaneous implant represents a foreign body, and the inflammation around it results from the breakdown of defense mechanisms, or the immune system is overwhelmed by an antigenic load [9]. Skin inflammation and infection around the abutment are the most common complications in BAHA surgery. The goals of soft tissue handling are to decrease the mobility of the soft tissue relative to the bone, hairless skin and a gentle slope of the soft tissue toward the implant. Local irritation and skin regrowth around the abutment are the most common skin problems in BAHA patients [10]. Since the onset of BAHA surgery, the surgical techniques of creating a skin flap with a dermatome, and the linear incision with subcutaneous tissue reduction have been in use. Mudry found statistically significant differences in unscheduled consultations in the skin flap group from skin irritations and crusting. He discovered that the linear incision technique lowered the risks of skin problems [11]. De Wolf [12] found no differences in longterm complication rates between the techniques. Local factors for better wound healing include an oxygen supply, which could be hampered by low
123
vascularization. Preventive applications, optimizing wound perfusion and providing supplemental O2 in the perioperative period reduce the incidence of postoperative infections. Adequate wound tissue oxygenation is required but may not be sufficient to influence healing outcomes favorably [13]. Nutritional status also plays an important role in wound healing, and ignoring it may compromise healing [14]. Comorbidities like diabetes or dermatological and other systemic diseases certainly contribute to complication rates in patients with BAHA [9]. In our patient with the implant loss, blood sugar levels were within normal range, but his BMI was above 25 kg/m2. The other two patients who reached grade 4 in Holgers classification were overweight (BMI above 30 kg/m2), and one of them had elevated levels of blood sugar and plasmacytoma. The second is younger and does not have diabetes so far. There were no diabetic patients in the other patient population. Our results indicate that patients with a higher BMI have significantly more skin problems than patients with a lower BMI. Similar observations were reported by Berenholz [15], who found increased rates of soft tissue complications in patients with BMI greater than 30. Some studies [16] showed higher incidence of skin reactions, but we could not prove any correlation between the age and Holgers grades. Our group of younger patients was relatively small. In our series, three patients with Holgers grade 4 had to be fitted with longer (8.5 mm) abutments because of a thickening of skin. If skin overgrowth is occurring, the change to a longer abutment can be done as an ambulatory procedure or during the first surgical procedure to avoid frustration for both patient and surgeon in dealing with significant soft tissue reactions postoperatively. When handling adipose patients, it is advisable to use a longer abutment already during the first surgical procedure. Significantly more skin irritations appear in men than in women. This can probably be explained by women’s better hygiene but perhaps also by the patient’s occupation, which can contribute to additional inflammations. Androgens may increase the tendency toward hypertrophic scarring as well and, contrarily, estrogens may exert an anti-inflammatory effect. In addition, a study by Monksfield [17] showed that the patients who required a longer abutment were predominantly male. It was necessary for us to change abutments in one woman and two men. We observed no deviations in patients with different indications for BAHA. In chronic otitis, the infection could have spread from the ear to the retroauricular region, and we could perhaps detect more soft tissue reactions in patients with chronic otitis media. The mean Holgers grades did not differ between patients with atresia and SSD, where no potential ear infection existed, and patients
Ir J Med Sci
with chronic otitis media. Perhaps a larger number of patients would produce different results. Still we must also consider other possibilities for skin inflammation around the abutment. The development of a biofilm on the abutment was recently described by Monksfield et al. [18]. It is also possible that peri-BAHA dermal reactions may arise in response to oxidation products. Exudate around the abutment could favor colonization of bacteria. It became evident during follow-up that the degree of soft tissue reactions in our patients was changing through the years. Some of them had almost no local reaction at all. They were more frequent in others and disappeared after local therapy. The percentage of patients with a Holgers grade of more than 2 was about 20 % in the first 2 years and then declined to less than 10 % in the third and fourth year. Probably, during this time patients had learned how to manage the soft tissues around the abutment and to recognize situations that provoked inflammation. Instructions on how to clean the abutment site seem to be very important during the first months after surgery. Some men and other patients with a higher BMI index are more prone to develop soft tissue reactions and should be supplied with longer abutments from the start. Future goals are certainly to improve soft tissue adherence to the abutment, reduce pocket formation and create a bacterial barrier, which is believed to be the key to maintaining good soft tissue health. Three years ago a new surgical technique without soft tissue reduction was published [19]. New abutment covered with hydroxyapatite was developed. It does not need soft tissue reduction and seems promising regarding the skin reactions [20]. Recently transcutaneous bone conduction devices are also available. They do not exceed percutaneous device regarding audiologic output, but offer a possibility in patients where soft tissue reactions can be expected [21]. It will be interesting to compare the degree of skin reactions in patients operated with and without soft tissue reduction in the future. Conflict of interest
The author discloses no conflicts of interest.
References 1. Tjellstro¨m A, Ha˚kansson B (1995) The bone-anchored hearing aid. Design principles, indications and long-term clinical results. Otolaryngol Clin North Am 28(1):53–72 2. Tjellstro¨m A, Granstro¨m G (2006) How we do it: frequency of skin necrosis after BAHA surgery. Clin Otolaryngol 31:216–232
3. De Wolf MJF, Hol MKS, Mylanus EAM, Cremers C (2009) Bone-anchored hearing aid surgery in older adults: implant loss and skin reactions. Ann Otol Rhinol Laryngol 118(7):525–531 4. Wazen JJ, Young DL, Farrugia MC et al (2008) Successes and complications of the BAHA system. Otol Neurotol 29:1115–1119 5. Holgers KM, Tjellstro¨m A, Bjursten LM, Erlandson BE (1988) Soft tissue reactions around percutaneous implants: a clinical study of soft tissue conditions around skin penetrating titanium implants for bone anchored hearing aids. Am J Otol 9:56–59 6. Holgers KM (2000) Characteristics of the inflammatory process around skin-penetrating titanium implants for aural rehabilitation. Audiology 39:253–259 7. Dun CA, de Wolf MJ, Hol MK, Wigren S, Eeg-Olofsson M, Green K et al (2011) Stability, survival, and tolerability of a novel Baha implant system: six-month data from a multicenter clinical investigation. Otol Neurotol 32(6):1001–1007 8. Bray GA (1987) Overweight is risking fate. Definition, classification, prevalence and risks. Ann N Y Sci 499:14–28 9. Wazen JJ, Wycherly B, Daugherty J (2011) Complication of bone–anchored hearing devices. In: Kompis M, Caversaccio M (eds) Implantable hearing aids. Adv Otorhinolaryngol Karger Basel vol 71, pp 63–72 10. Ricci G, Della Volpe A, Faralli M, Longari F, Gulla M, Mansi N, Frenguelli A (2010) Results and complications of the BAHA system (bone anchored hearing aid). Eur Arch Otorhinolaryngol 267:1539–1545 11. Mudry A (2009) Bone anchored hearing aids (BAHA): skin healing process for skin flap technique versus linear incision technique in the first three months after the implantation. Rev Laryngol Otol Rhinol 130(5):281–284 12. de Wolf MJF, Hol MKS, Huygen PLM, Mylanus EAM, Cremers CWRJ (2008) Clinical outcome of the simplified surgical technique for BAHA implication. Otol Neurotol 29(8):1100–1108 13. Sen CK (2009) Wound healing essentials: let there be oxygen. Wound Repair Regen 17(1):1–18 14. Russel L (2001) The importance of patients’ nutritional status in wound healing. Br J Nurs 10(6 (Suppl)):44–49 15. Berenholz LP, Burkey JM, Lippy WH (2010) High body mass index as a risk factor for skin overgrowth with the bone— anchored hearing aid. Otol Neurotol 31:430–432 16. Reyes RA, Tjellstroem A, Granstroem G (2000) Evaluation of implant losses and skin reactions around extraoral bone-anchored implants: a 0- to 8-year follow-up. Otolaryngol Head Neck Surg 122(2):272–276 17. Monksfield P, Ho EC, Reid A, Proops D (2009) Experience with the longer (8.5 mm) abutment for bone-anchored hearing aid. Otol Neurotol 30:274–276 18. Monksfield P, Chapple ILC, Matthews JB, Grant MM, Addison O, Reid AP, Proops DW, Sammons RL (2011) Biofilm formation on bone anchored hearing aids. J Laryngol Otol 125:1125–1130 19. Hultcrantz M (2011) Outcome of the bone-anchored hearing aid procedure without skin thinning: a prospective clinical trial. Otol Neurotol 32(7):1134–1139 20. Larsson A, Wigren S, Andersson M, Flynn M, Nannmark U (2012) Histologic evaluation of soft tissue integration of experimental abutments for bone anchored hearing implants using surgery without soft tissue reduction. Otol Neurotol 33(8):1445–1451 21. Hol MK, Nelissen RC, Agterberg MJ, Cremers CW, Snik AF (2013) Comparison between a new implantable transcutaneous bone conductor and percutaneous bone-conduction hearing implant. Otol Neurotol 34(6):1071–1075
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ORIGINAL ARTICLE
Soft tissue reactions in patients with bone anchored hearing aids J. Rebol
Received: 4 February 2014 / Accepted: 21 May 2014 Ó Royal Academy of Medicine in Ireland 2014
Abstract Aims To establish the incidence and correlation between the degree of soft tissue reaction and the body mass index (BMI) according to age and gender after a bone anchored hearing aid (BAHA) implant. Methods We did a 1–9-year follow-up for the all the patients who underwent surgery in our department with BAHA implant system. Soft tissue reactions were classified in accordance with the Holgers classification on regular patient visits. BMI was calculated for each patient, and changes were recorded at least once a year. Results 47 patients were evaluated. 58 % were operated on for chronic otitis with mixed or conductive hearing loss; 20 % had unilateral or bilateral atresia and 16 % had single sided deafness (SSD); other indications were otosclerosis and syndromic patients. The grade of Holgers classification significantly correlated at a 0.001 level with BMI (Spearmans rho 0.452). Holgers grade also differed significantly between the sexes–skin reactions in females were less frequent. An ANOVA test did not reveal any statistical difference between patients with dissimilar indications for BAHA. Conclusion If performed carefully, BAHA surgery produces a favorable outcome. The Holgers grade may change as time passes. If skin reactions appear, they can be treated through local or systemic therapy, and they may turn into a normal grade. Adipose patients should be treated with special care because they are more prone to soft tissue reactions.
J. Rebol (&) Maribor University Hospital, Ljubljanska 5, 2000 Maribor, Slovenia e-mail: [email protected]
Keywords Bone anchored hearing aid Skin reaction Holgers classification Body mass index
Introduction The bone anchored hearing aid (BAHA) system consists of bone anchored titanium implant, abutment and processor, which is attached to the abutment (Fig. 1). It is a percutaneous device and was first applied to patients with significant bilateral conductive or mixed hearing loss in which middle ear surgery can not bring any improvement and can not wear conventional hearing aids. Because of its success, indications have been extended. Audiological indications now include conductive and mixed hearing loss and single side deafness. Medical indications include radically operated patients with chronic otitis, atresia of external ear canal, patients who loose their hearing in vestibular schwannomma surgery and otosclerosis [1]. The first BAHA operation was accomplished in 1977; in 1989, the standard two-stage procedure was exchanged for a single procedure that already concerned itself with how skin should react in the immediate postoperative period and in the long run. During the early years of BAHA surgery, either no or minimum soft tissue thinning was done. Patient follow-up made it clear that skin mobility in relation to the implant involved the risk of adverse tissue reactions. During the 1980s, a hairless skin graft was taken from the retroauricular fold. With this technique, the frequency of partial necrosis was 15.7 % and there was total necrosis in 0.9 %. About that time the application of a free skin graft around the abutment was abandoned. An anteriorly based pedicled flap was added, and it was thinned with a blade. The frequency of partial necrosis was found to be 9.8 % and total necrosis 0.6 %. A specially designed dermatome
123
Ir J Med Sci
Fig. 1 BAHA device in place located retroauricularly in patient with microtia and atresia of the external ear canal
was introduced in 2001. The flap width in this technique is 25 mm and its thickness is fixed at 0.6 mm. In addition, all hair follicles have to be removed from the underlying tissue. Only the innermost periost layer is left in a space of 5–7 mm around the coupling. The incidence of minor skin necrosis in Tjellstro¨m’s series was 3.0 % [2] with the dermatome technique. Depending on the BAHA implant center and duration of follow-up, implant loss rates have varied 3.5–17.4 % in adults and 5.3–30 % in children. In a study by de Wolf et al., [3] the total rate of implant loss was 6.5 % in almost 250 patients; 3.6 % was due to osseointegration failure. The authors suggest that one of the advantages of the linear incision technique is the prevention of skin flap necrosis. Soft tissue reactions after BAHA surgery are infrequent, but they do occur. Wazen reported 8.1 % of patients requiring local care for cellulitis, granular dermatitis, pain, neuralgia, and immediate postoperative complications such as bleeding or dehiscence [4]. The probability of losing an implant because of adverse skin reactions is quite low; however, skin reactions, if left untreated, may eventually lead to implant loss or withdrawal. Our clinical impression is that soft tissue complications with BAHA are most common in patients with thick subcutaneous tissue at the implant site. Elevated body mass index (BMI) could be used as a predictor of soft tissue complications. In these patients the use of 8.5 mm abutment could prevent subsequent problems.
Materials and methods All patients were operated in our department. The followup period was between 1 and 9 years. We noted the
123
Fig. 2 BAHA abutment in the same patient as in Fig. 1. Note flat skin with no skin inflammation around the abutment–Holgers grade 0
Fig. 3 Inflammation and skin overgrowth around the abutment– Holgers grade 4
indications for surgery, age, side of the BAHA application; on regular controls, soft tissue reactions around the abutment were noted and categorized according to Holgers classification. The Holgers grading system of postoperative skin irritation is now widely used for describing the state of the skin around the abutment [5, 6]. Grade 0 means no irritation (Fig. 2); grade 1, slight redness; grade 2, red and moist tissue; grade 3, granulation tissue, and grade 4, infection leading to removal of the abutment (Fig. 3). Grades 1–2 can be treated with local therapy, grades 3–4 may require oral antibiotic therapy or even excision of the skin if overgrowth develops. The author performed the dermatome technique on all patients with the appropriate subcutaneous thinning in order to prevent immediate or delayed skin reactions.
Ir J Med Sci
Fig. 4 Percentage of patients with grade 2? of Holgers classification during 9 years observation period
Fig. 5 Holgers grade in 6 patients with 9 years experience
Operations on adult patients were performed using local anesthesia, children and syndromic patients with general anesthesia. During the last 3 years, the BI300 implant [7] has been used in surgery; before that, an implant of a previous generation had been used. Before surgery, pure tone averages for bone and air conduction in the operated ear were calculated at 0.5, 1, 2, and 3 kHz. Body mass index [8] was calculated from the data recorded at the time of surgery. BMI is defined as the individual’s body weight divided by the square of his or her height. The formula universally used in medicine produces a unit of measure of kg/m2. Body mass index groups are defined as underweight if the BMI is less than 18.5 kg/m2, normal 18.5–24.9 kg/m2, overweight 25.0–29.9 kg/m2, or obese greater than 30 kg/m2.
Table 1 Correlation coefficients for BMI (body mass index) BMI Age
0.503
Holgers grade
0.452
In bold-correlation is significant at the 0.001 level (Spearman’s rho coefficient)
Table 2 Differences in age, mean Holgers grade, body mass index (BMI) and air bone gap (ABG) between sexes—men (m), women (w)
Gender
Mean
Std. deviation
M
45.40
18.71
W
43.28
16.81
Age
Holgers grade M
1.27
1.33
W
0.36
0.63
M
27.06
7.11
W
24.32
5.35
BMI
Results Our follow-up covered 15 men and 32 women who had undergone surgery from 2 to 10 years ago. Their average age was 43 years; five patients were younger than 16 years; the youngest was 7 years old and the oldest 72. The indications for the operations were in 55.3 % radically operated chronic otitis, bilateral atresia in 14.9 %, unilateral atresia in 6.3 %, idiopathic single sided deafness in 4.3 %, single sided deafness after vestibular schwannoma removal in 4.2 %, otosclerosis in 4.3 and 2.1 % with Down syndrome and conductive hearing loss. In Fig. 4, the percentage of patients with a Holgers grade of more than or equal to 2 is shown. In our 9-year observation period, the percentage of these patients varied between 6 and 22 %. Seventeen patients had at least 4 years of BAHA experience. Seven of them showed variations of Holgers grade during that time or their Holgers grade was above 0. In the remaining 10 patients, the skin around the BAHA abutment showed no abnormalities. Six of our patients had 9 years of BAHA experience. Holgers grade reached grade 3 in two of them and then
Difference in Holgers grade is statistically significant at 0.001 level In bold-correlation is significant at the 0.001 level (Spearman’s rho coefficient)
ABG (dB) M
40.92
12.76
W
40.20
9.63
returned to grade 0. In one patient, the Holgers grade varied between 0 and 1, and in two patients it remained at 0 the whole time. In the entire patient population, only three reached grade 4, and in one of these patients, we had an implant loss 7 months after surgery caused by osseointegration failure (Fig. 5). The mean values for BMI for men and women were 27.06 and 24.32 kg/m2. In men this index recorded overweight and in women, normal weight. BMI did not correlate with the age of the patients. Holgers grade significantly correlates with BMI at the 0.001 level (Table 1). Both sexes had almost the same age and air bone gap. There was a marked difference between the sexes in Holgers grade, which was higher in males (Table 2). We also looked at Holgers grades in different BAHA indications. Maximal values differed significantly, but the
123
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Fig. 6 Holgers grade dynamics. 45.9 % had constantly grade 0, constant grade had 8.1 %, falling grade was observed in 16.2 %, increasing in 10.8 %, increasing then falling in 16.2 % and oscillating in 2.7 %
mean values were much the same. ANOVA test did not show significant differences between the indications. Holgers grade dynamics is shown in the Fig. 6. In 29 % the skin conditions around the implant were unstable (increasing, oscillating or increasing and then falling). The other patients had either constant Holgers grade 0, constant other Holgers grade or falling Holgers grade.
Discussion The percutaneous implant represents a foreign body, and the inflammation around it results from the breakdown of defense mechanisms, or the immune system is overwhelmed by an antigenic load [9]. Skin inflammation and infection around the abutment are the most common complications in BAHA surgery. The goals of soft tissue handling are to decrease the mobility of the soft tissue relative to the bone, hairless skin and a gentle slope of the soft tissue toward the implant. Local irritation and skin regrowth around the abutment are the most common skin problems in BAHA patients [10]. Since the onset of BAHA surgery, the surgical techniques of creating a skin flap with a dermatome, and the linear incision with subcutaneous tissue reduction have been in use. Mudry found statistically significant differences in unscheduled consultations in the skin flap group from skin irritations and crusting. He discovered that the linear incision technique lowered the risks of skin problems [11]. De Wolf [12] found no differences in longterm complication rates between the techniques. Local factors for better wound healing include an oxygen supply, which could be hampered by low
123
vascularization. Preventive applications, optimizing wound perfusion and providing supplemental O2 in the perioperative period reduce the incidence of postoperative infections. Adequate wound tissue oxygenation is required but may not be sufficient to influence healing outcomes favorably [13]. Nutritional status also plays an important role in wound healing, and ignoring it may compromise healing [14]. Comorbidities like diabetes or dermatological and other systemic diseases certainly contribute to complication rates in patients with BAHA [9]. In our patient with the implant loss, blood sugar levels were within normal range, but his BMI was above 25 kg/m2. The other two patients who reached grade 4 in Holgers classification were overweight (BMI above 30 kg/m2), and one of them had elevated levels of blood sugar and plasmacytoma. The second is younger and does not have diabetes so far. There were no diabetic patients in the other patient population. Our results indicate that patients with a higher BMI have significantly more skin problems than patients with a lower BMI. Similar observations were reported by Berenholz [15], who found increased rates of soft tissue complications in patients with BMI greater than 30. Some studies [16] showed higher incidence of skin reactions, but we could not prove any correlation between the age and Holgers grades. Our group of younger patients was relatively small. In our series, three patients with Holgers grade 4 had to be fitted with longer (8.5 mm) abutments because of a thickening of skin. If skin overgrowth is occurring, the change to a longer abutment can be done as an ambulatory procedure or during the first surgical procedure to avoid frustration for both patient and surgeon in dealing with significant soft tissue reactions postoperatively. When handling adipose patients, it is advisable to use a longer abutment already during the first surgical procedure. Significantly more skin irritations appear in men than in women. This can probably be explained by women’s better hygiene but perhaps also by the patient’s occupation, which can contribute to additional inflammations. Androgens may increase the tendency toward hypertrophic scarring as well and, contrarily, estrogens may exert an anti-inflammatory effect. In addition, a study by Monksfield [17] showed that the patients who required a longer abutment were predominantly male. It was necessary for us to change abutments in one woman and two men. We observed no deviations in patients with different indications for BAHA. In chronic otitis, the infection could have spread from the ear to the retroauricular region, and we could perhaps detect more soft tissue reactions in patients with chronic otitis media. The mean Holgers grades did not differ between patients with atresia and SSD, where no potential ear infection existed, and patients
Ir J Med Sci
with chronic otitis media. Perhaps a larger number of patients would produce different results. Still we must also consider other possibilities for skin inflammation around the abutment. The development of a biofilm on the abutment was recently described by Monksfield et al. [18]. It is also possible that peri-BAHA dermal reactions may arise in response to oxidation products. Exudate around the abutment could favor colonization of bacteria. It became evident during follow-up that the degree of soft tissue reactions in our patients was changing through the years. Some of them had almost no local reaction at all. They were more frequent in others and disappeared after local therapy. The percentage of patients with a Holgers grade of more than 2 was about 20 % in the first 2 years and then declined to less than 10 % in the third and fourth year. Probably, during this time patients had learned how to manage the soft tissues around the abutment and to recognize situations that provoked inflammation. Instructions on how to clean the abutment site seem to be very important during the first months after surgery. Some men and other patients with a higher BMI index are more prone to develop soft tissue reactions and should be supplied with longer abutments from the start. Future goals are certainly to improve soft tissue adherence to the abutment, reduce pocket formation and create a bacterial barrier, which is believed to be the key to maintaining good soft tissue health. Three years ago a new surgical technique without soft tissue reduction was published [19]. New abutment covered with hydroxyapatite was developed. It does not need soft tissue reduction and seems promising regarding the skin reactions [20]. Recently transcutaneous bone conduction devices are also available. They do not exceed percutaneous device regarding audiologic output, but offer a possibility in patients where soft tissue reactions can be expected [21]. It will be interesting to compare the degree of skin reactions in patients operated with and without soft tissue reduction in the future. Conflict of interest
The author discloses no conflicts of interest.
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