10.14639/0392-100X-N1048
Objectives. To evaluate mean surgical time, incidence of soft tissue reactions, implant survival and intraoperative complications in both minimally invasive ponto surgery (MIPS) and the linear incision with tissue preservation technique (LT).Methods. A retrospective review was carried out on 48 bone anchored hearing system (BAHS) patients between 2014 and 2019: 13 patients had undergone LT and formed one group, while 35 patients had undergone MIPS and formed the second group. Mean surgical time, intraoperative complications, implant loss and skin reaction were assessed at each post-operative examination. The Mann-Whitney U test was used for statistical analysis.Results. The difference in the mean surgical time of 15 mins for MIPS and 36 mins for LT was statistically significant. No intraoperative complications were reported and implant survival was 100% in both groups. The incidence of adverse skin reactions was 7.7% for the LT group and 0% for the MIPS group at first follow-up examination.Conclusions. Surgical mean time is shorter for MIPS, making this procedure more suitable for local anaesthesia and more cost effective. Moreover, both LT and MIPS demonstrate good surgical outcomes in terms of skin reactions according to Holgers score and equally excellent implant survival.
text/xml
1827-675X
1048
en
Domenico Cuda
http://creativecommons.org/licenses/by-nc-nd/4.0
ACTA Otorhinolaryngologica Italica
bone anchored hearing system
Comparison between linear incision and punch techniques for bone anchored hearing aid surgery
Text.Serial.Journal
https://www.actaitalica.it/
41
Otology
2021-11-05
2020-08-08
2021-11-02
2021-11-02
474-480
1
Domenico Cuda
2021/11/05
10.14639/0392-100X-N1048
474
Department of Otorhinolaryngology, “Guglielmo da Saliceto” Hospital, Piacenza, Italy
1827-675X
bone anchored hearing system
en
480
Comparison between linear incision and punch techniques for bone anchored hearing aid surgery
https://www.actaitalica.it/article/download/1048/684
41
ACTA OTORHINOLARYNGOLOGICA ITALICA 2021;41:474-480; doi: 10.14639/0392-100X-N1048




Otology


Comparison between linear incision and punch
techniques for bone anchored hearing aid surgery
Confronto tra incisione lineare e tecnica punch nella chirurgia degli impianti
a conduzione ossea
Sabrina De Stefano1, Paolo Mochi2, Alessandra Murri2, Domenico Cuda2
1
 Department of Otorhinolaryngology and Otoneurosurgery, University Hospital of Parma, Parma, Italy; 2 Department of
Otorhinolaryngology, “Guglielmo da Saliceto” Hospital, Piacenza, Italy


SUMMARY
Objectives. To evaluate mean surgical time, incidence of soft tissue reactions, implant sur-
vival and intraoperative complications in both minimally invasive ponto surgery (MIPS)
and the linear incision with tissue preservation technique (LT).
Methods. A retrospective review was carried out on 48 bone anchored hearing system
(BAHS) patients between 2014 and 2019: 13 patients had undergone LT and formed one
group, while 35 patients had undergone MIPS and formed the second group. Mean surgical
time, intraoperative complications, implant loss and skin reaction were assessed at each
post-operative examination. The Mann-Whitney U test was used for statistical analysis.
Results. The difference in the mean surgical time of 15 mins for MIPS and 36 mins for LT
was statistically significant. No intraoperative complications were reported and implant
survival was 100% in both groups. The incidence of adverse skin reactions was 7.7% for
the LT group and 0% for the MIPS group at first follow-up examination.                          Received: August 12, 2020
Conclusions. Surgical mean time is shorter for MIPS, making this procedure more suitable        Accepted: March 13, 2021
for local anaesthesia and more cost effective. Moreover, both LT and MIPS demonstrate
good surgical outcomes in terms of skin reactions according to Holgers score and equally        Correspondence
excellent implant survival.                                                                     Sabrina De Stefano
                                                                                                Department of Otorhinolaryngology, “Guglielmo
KEY WORDS: minimally invasive ponto surgery, linear incision technique with tissue              da Saliceto” Hospital, via Cantone del Cristo 40,
preservation, bone anchored hearing system                                                      29121 Piacenza, Italy
                                                                                                E-mail: sbrndestefano@gmail.com
RIASSUNTO
Obiettivo. Confrontare la tecnica dell’incisione lineare con conservazione del tessuto          Funding
sottocutaneo (LT) e la tecnica MIPS valutando le differenze nella durata della chirurgia,       None.
l’incidenza delle reazioni cutanee avverse, la perdita dell’impianto e le complicanze in-
traoperatorie.                                                                                  Conflict of interest
                                                                                                The Authors declare no conflict of interest.
Metodi. Presso il nostro centro di Audiologia tra il 2014 e 2019 sono stati sottoposti ad
intervento chirurgico per l’applicazione di BAHS 48 pazienti: 13 pazienti mediante LT e 35
pazienti mediante MIPS.                                                                           How to cite this article: De Stefano S, Mo-
Risultati. La durata media della chirurgia è stata di 15 minuti per la tecnica MIPS e 36          chi P, Murri A, et al. Comparison between lin-
minuti per la LT con una differenza statisticamente significativa. Non sono state riscontrate     ear incision and punch techniques for bone
complicanze intraoperatorie, la perdita dell’impianto è stata dello 0% in entrambi i gruppi.      anchored hearing aid surgery. Acta Otorhi-
L’incidenza di reazioni avverse cutanee è stata del 7,7% per il gruppo LT e dello 0% per il       nolaryngol Ital 2021;41:474-480. https://doi.
                                                                                                  org/10.14639/0392-100X-N1048
gruppo MIPS alla prima visita post-operatoria.
Conclusioni. La durata dell’intervento chirurgico è più breve per la MIPS rispetto alla
                                                                                                © Società Italiana di Otorinolaringoiatria
tecnica LT, rendendo questa procedura più adatta all’anestesia locale e più vantaggiosa in      e Chirurgia Cervico-Facciale
termini di costi sanitari. Inoltre, sia la LT che la MIPS mostrano buoni risultati chirurgici
per quanto riguarda la riduzione delle reazioni cutanee avverse, le complicanze intraope-
                                                                                                               OPEN ACCESS
ratorie e la perdita dell’impianto.
                                                                                                This is an open access article distributed in accordance with
PAROLE CHIAVE: chirurgia mininvasiva ponto, incisione lineare, protesi acustica                 the CC-BY-NC-ND (Creative Commons Attribution-Non-
ancorata all’osso                                                                               Commercial-NoDerivatives 4.0 International) license. The
                                                                                                article can be used by giving appropriate credit and mentio-
                                                                                                ning the license, but only for non-commercial purposes and
                                                                                                only in the original version. For further information: https://
                                                                                                creativecommons.org/licenses/by-nc-nd/4.0/deed.en




474
                                                                 Surgical outcomes of bone anchored hearing aid surgery: a retrospective analysis




Introduction                                                        had their first follow-up examination around 15 days after
                                                                    surgery and the second follow-up examination between 1
Bone anchored hearing systems (BAHS) were introduced                to 2 months after surgery, usually coinciding with sound
for the first time in 1977 and have significantly improved          processor loading and activation. Additional data from
the quality of life and the hearing ability of patients with
                                                                    follow-up visits were included. The mean follow-up time
conductive or mixed hearing loss since then 1. The BAHS
                                                                    was 42 months for the LT group and 14 months for the
consists of a fixture implanted in the temporal bone, an
                                                                    MIPS group. The duration of BAHS surgery and intraop-
abutment breaching the skin barrier and a sound processor
                                                                    erative complications were also evaluated. Furthermore,
coupled to the abutment. When the osseointegration of the
                                                                    implant loss and skin reactions grading by Holgers score
fixture is complete, the vibrations reach the otic capsule
                                                                    system 8 (Tab. I) were assessed at every post-operative ex-
through the temporal bone without any soft tissue dampen-
                                                                    amination. The data were then analysed using IBM SPSS
ing and evoke basilar membrane and hair cell stereociliary
                                                                    Statistics for Windows, Version 20.0. (Armonk, NY: IBM
deflections 2,3. For many years, different surgical techniques
                                                                    Corp.). The Mann-Whitney U test was used for statistical
including wide soft tissue reduction around the abutment
                                                                    analysis and a p-value < 0.05 was considered significant.
were considered to be the gold standard. A thin tissue was
                                                                    Lastly, the present study was reviewed and approved by the
believed to reduce the related implant mobility and thereby
                                                                    regional ethics committee (Approval number: 361.2018.
prevent skin overgrowth 4. However, these skin thinning
                                                                    DISP.AUSLPC).
procedures were related to significant complications such
as flap infections, necrosis with healing by second inten-
                                                                    Linear incision technique
tion and skin overgrowth around the abutment, thus neces-
                                                                    The site of implantation was placed about 55 mm posterior
sitating further tissue reduction procedures 4. Less invasive
                                                                    and superior to the external auditory canal and was marked
surgical techniques without subcutaneous tissue reduction
                                                                    with dye. The skin thickness was measured using a needle
have been developed in recent years. The “linear incision
                                                                    and forceps to choose the correct abutment length. Local
with tissue preservation” technique (LT) was first described
                                                                    anaesthetic infiltration was provided, and then a 30 mm
by Hultcrantz in 2011 4. The LT results in less scarring,
                                                                    long incision deep into the periosteum was made near the
good sensibility around the abutment and better cosmetics
                                                                    dye. The incision was widened using a retractor, and the
compared to previous surgical procedures using skin thin-
                                                                    periosteum was gently detached from the bone. The hole
ning 5. More recently, the minimally invasive ponto surgery
                                                                    for the fixture was drilled under saline irrigation in the tem-
(MIPS) technique has been introduced. MIPS is an even
                                                                    poral bone after which a punch was used to obtain a soft
less traumatic surgery in which only a punch is used to re-
                                                                    tissue hole at the dye marker in front of the linear incision
move tissue where the implant is then placed 6,7. The aim
                                                                    through which the fixture was placed without any other
of the present study was to compare surgical post-operative
                                                                    surrounding soft tissue removal. Following this, the fixture
outcomes of the LT technique with those of MIPS.
                                                                    with pre-mounted abutment was set in place and a healing
                                                                    cap was then placed over the abutment, and finally the skin
Materials and methods                                               was sutured.
A retrospective review of all patients referred to the AUSL
Piacenza centre who underwent BAHS surgery between                  MIPS technique
2014 and 2019 was carried out. In total, surgical and fol-          The site of implantation as well as the skin thickness meas-
low-up data on 48 patients was collected. Of these, LT              urement are the same as in the previous procedure. After
was performed in 13 patients between 2014 and 2017 and              the local anaesthetic injection, a punch was used to cut a
35 patients underwent surgery using the MIPS technique              cylinder of skin and subcutaneous tissue in a single step
between 2017 and 2019. The surgical time was recorded
starting from the local anaesthetic infiltration until the
                                                                    Table I. Holgers classification system for BAHS.
placement of healing cup for both procedures. All of the
                                                                     Grade    Description
operations were performed in a single stage by two expe-
rienced surgeons under local anaesthesia except for two              0          Normal skin around the abutment
patients who received general anaesthesia because canal              1          Redness around the abutment
wall up tympanoplasty was carried out during the same                2          Redness, moistness and moderate swelling
surgical procedure; only the surgical time for the BAHS              3          Redness, moistness and moderate swelling with tissue
implantation procedure was considered in these two cases.                       granulation around the abutment
The patients from the LT group and from the MIPS group               4          Signs of infection resulting in removal of the implant




                                                                                                                                           475
S. De Stefano et al.




                                                                                 (Fig. 1A and 1B). Next, the periosteum was gently dis-
                                                                                 sected and detached from the underlying bone using a peri-
                                                                                 osteal elevator. Following this, the bone was drilled using a
                                                                                 cannula under copious irrigation to protect the surrounding
                                                                                 tissue and then both the fixture and the abutment were set
                                                                                 in place (Fig. 2). Lastly, a healing cap was applied over the
                                                                                 abutment.
                                                                                 At the end of both procedures, gauze covered in steroid-
                                                                                 antibiotic ointment (0.1% gentamicin + 0.05% betameth-
                                                                                 asone) was applied around the abutment under the healing
                                                                                 cup.

                                                                                 Results
Figure 1A and 1B. The punch is used to cut a cylinder of skin and subcu-
taneous tissue in a single step.                                                 The ages of the cohort ranged from 19 to 81 years, the ma-
                                                                                 jority of patients (58.3%) being 51 to 75 years of age with
                                                                                 a predominance of women (68.7%) (Tab. II). The implants
                                                                                 used were Ponto Wide (N = 38) and Ponto BHX (N = 10)
                                                                                 with pre-mounted abutments (all produced by Oticon Med-
                                                                                 ical AB, Askim, Sweden). The skin thickness of patients
                                                                                 varied from 3 to 11 mm, making use of all available abut-
                                                                                 ment lengths (Tab. III). The mean surgical time was 15 min
                                                                                 for MIPS (SD 6, range 7-25 mins) and 36 mins for LT (SD
                                                                                 10, range 27-62 mins). This difference was statistically sig-
                                                                                 nificant (p < 0.001). No intraoperative complications were
                                                                                 reported in either group. The wounds were completely
                                                                                 healed (no skin reactions, Holgers = 0) at first follow-up
                                                                                 examination in all patients except for one in the LT group
                                                                                 (Holgers = 3), which was most likely caused by excessive
                                                                                 bandage compression. This patient was successfully treat-
                                                                                 ed with oral and topical antibiotics for one week. No skin
                                                                                 overgrowth, skin dehiscence or retroauricular pain were de-
                                                                                 tected in either group. Implant survival was 100% in both
                                                                                 groups. At first follow-up examination, the incidence of
                                                                                 adverse skin reactions was 7.7% for LT and 0% for MIPS
                                                                                 (Fig. 3A and 3B, Tab. III). In fact, 98% of the wounds were
                                                                                 scored with Holgers = 0. At second and at last follow-up
Figure 2. Under copious irrigation the bone drilling is performed using a can-   examinations, no adverse skin reactions were reported in
nula to protect the surrounding tissue.                                          either group. As an example, Figure 4 shows the outcome


Table II. Cohort features.
                                                               Linear incision                   MIPS                         All
 Age (N, %)
   18-50 years                                                    1 (7.6%)                     15 (42.8%)                  16 (33.3%)
   51-75 years                                                   11 (84,6%)                    17 (48.5%)                  28 (58.3%)
   > 75 years                                                     1 (7.6%)                      3 (8.5%)                    4 (8.3%)
 Gender (N, %)
   Men                                                           2 (15.3%)                     13 (37.1%)                  15 (31.2%)
   Women                                                         11 (84.6%)                    22 (62.8%)                  33 (68.7%)




476
                                                                          Surgical outcomes of bone anchored hearing aid surgery: a retrospective analysis




Table III. Surgical data.
                                                          Linear incision                         MIPS                                 All
 Implant (N, %)
   Wide Ponto                                               13 (100%)                          25 (71.4%)                         38 (79.1%)
   Ponto BHX                                                     -                             10 (28.5%)                         10 (20.8%)
 Abutment length (N, %)
   6 mm                                                     2 (15.3%)                           4 (11.4%)                         6 (12.5%)
   9 mm                                                     9 (69.2%)                          17 (48.5%)                         26 (54.1%)
   12 mm                                                    2 (15.3%)                          13 (37.1%)                         15 (31.2%)
   14 mm                                                        -                               1 (2.8%)                            1 (2%)
 Surgical duration (min)                                     36 min                              15 min
 Adverse skin reactions (%)                                   7.7%                                 0%




                                                                             Figure 4A and 4B. Comparison of healed wound appearance of MIPS
                                                                             and LT.


                                                                             years and all of the surgical techniques were based on skin
                                                                             thinning procedures to remove subcutaneous tissue in the
                                                                             area around the abutment and either attach a skin graft or a
                                                                             skin flap directly onto the periosteum 5.
                                                                             Surgical outcomes of different techniques have varied over
Figure 3A and 3B. Skin reactions scored by Holgers grading scale for LT      the years 9. The most common complications addressed have
group and for MIPS group at first follow-up visit.                           been skin infections, flap necrosis and skin overgrowth as
                                                                             well as numbness and poor cosmetic appearance 10. All of
of the wound and of the area around the abutment from a                      these complications can impact the satisfaction and accept-
distance.                                                                    ance of the device by patients. Most of the complications
                                                                             were associated with extensive soft tissue reduction around
                                                                             the abutment to reduce the mobility of the implants. The
Discussion
                                                                             removal of all of the sebaceous glands and hair follicles
Since the introduction of BAHS over 40 years ago, the                        was thought to reduce the rate of skin infection and inflam-
hearing ability and quality of life of patients with conduc-                 mation, but previous studies have demonstrated that tissue
tive or mixed hearing losses have benefitted from the use of                 thinning was only a theoretical benefit 4,9,11. The patients
implants 1. The surgical technique to place the implants in                  of our sample did not require any device explantation due
the temporal bone did not change dramatically for several                    to complications. Barbara et al. described seven subjects



                                                                                                                                                    477
S. De Stefano et al.




out of 52 with a percutaneous device that needed explanta-         technique. The tissue cotton swab sensitivity test showed
tion because of skin complications, delayed osseointegra-          that the tissue preservation group had better sensitivity of
tion failure with fixture loss, or decreased bone conduction       the wound area and the difference was statistically signifi-
threshold 12.                                                      cant. In line with this result, 52% of patients in the tissue
During recent years less invasive surgical techniques with-        reduction group experienced numbness compared to 4% of
out subcutaneous tissue reduction have been developed, for         patients in the tissue preservation group 18.
example the linear incision with tissue preservation tech-         If skin thinning is found to be unnecessary, then the in-
nique was first described by Hultcrantz in 2011 4. It was          cision can even be avoided. In fact, the punch procedure
shown that after tissue reduction surgery, 43% of patients         was developed according to these new considerations, and
developed infections at the site of the abutment (Holgers          released 7. The punch procedure is an even less traumatic
1-3), whereas only one patient (14%) who underwent LT              surgery for BAHS. This technique does not need any tissue
without skin thinning developed an infection, and this pa-         reduction or an incision. It only needs a skin biopsy punch
tient got a Holgers score of 2 4. Moreover, LT with tissue         which removes a tissue cylinder down to the periosteum in
preservation was related to a reduction in numbness around         a single step 19.
the abutment, better cosmetic outcomes and reduced surgi-          An initial criticism of punch surgeries was poor visualisa-
cal time, and later became the new gold standard for BAHS          tion during the temporal bone drilling which could harm
surgical treatments. Van Der Stee et al. detected wound de-        the surrounding soft tissue and make the drilling process
hiscence in 28 implants that had been placed using LT with         more difficult for the surgeon 19. However, if the drill is
tissue reduction and 33.7% soft tissue reactions in the same       pointed perpendicularly to the underlying bone and there is
group of patients. In contrast, 27.6% of soft tissue reactions     copious irrigation, incision is still unnecessary. The drilling
in the LT with tissue preservation group were registered           step should be as short as possible and under copious cold
without any wound dehiscence 13. Furthermore, Badran et            irrigation to avoid heat damage, and the bone dust should
al. reported that patient satisfaction with skin appearance        be completely removed before the pre-mounted abutment
after tissue removal was not significantly better compared         is set in place. Furthermore, the surgical kit provided by
to the cosmetic impact of common hearing aids 14,15. On            Oticon Medical (MIPS) has a cannula that protects the sur-
the other hand, in patients who have benefitted from audi-         rounding tissue from heating and from any other trauma
tory implantable devices the quality of life improved with         during the drilling 20. An important result was that the mean
respect to wearing conventional hearing aids, but the aes-         surgical time is shorter for MIPS (15 min, SD 6) compared
thetic factor was not the most important aspect to consid-         with the LT (36 mins, SD 10), and this difference was sta-
er among BAHS users. In fact, Monini et al. showed that            tistically significant (p < 0.001). Gordon and Coelho re-
when patients experience less invasive and shorter surgical        ported a mean surgical time for MIPS of 13.4 mins against
procedure, they report a greater improvement in quality of         49.2 mins for LT with tissue reduction 19. Dumon et al.
life 16.                                                           compared the surgical time between MIPS and BAHS im-
An interesting hypothesis about histopathologic tissue             plantation using an epidermal flap and soft tissue removal
reactions in the case of excessive skin removal has been           (dermatome group) and found that mean duration for MIPS
proposed. The presence of the abutment breaching the skin          was 15 mins and the surgical mean duration was 30 mins in
barrier causes an inflammatory reaction that eventually            the dermatome group 21. In addition, the reported mean sur-
leads to the accumulation of immunoreactive cells around           gical time for MIPS in a multicentre study was 16 mins 17.
it. If a bacterial infection occurs in this area, which has been   The impressive reduction of surgical time of MIPS com-
surgically reduced, the amount of inflamed cells greatly           pared with other surgical procedures makes this technique
increases resulting in redness, granulation and skin necro-        more suitable for local anaesthesia and more cost effec-
sis. On the other hand, if the skin is not thinned, the blood      tive 22,23. Furthermore, Sardiwalla et al. investigated patient
vessels can carry healing agents and the response to the           satisfaction using a Surgical Satisfaction Questionnaire
infection is more effective. Therefore, tissue removal can         (SSQ-8) modified for MIPS and found that patient experi-
destroy the blood supply and can increase scar formation           ences with MIPS were overwhelmingly positive. Indeed,
around the abutment, reducing the chance of skin regen-            all patients reported speedy recovery and a short surgical
eration 4,17. Furthermore, the nerve fibres are also removed       experience 24. Limbrick et al. recently described a modified
during the skin thinning procedure causing a numb sensa-           minimally invasive technique (MMIT) consisting of a lin-
tion at the wound area. In a prospective study, Kruyt et al.       ear incision performed laterally each side of the soft tissue
compared the sensitivity and subjective numbness around            hole after the punch has been used. In this case, a linear
the abutment in tissue preservation and tissue reduction           incision allows better visualisation of the surgical field dur-



478
                                                                    Surgical outcomes of bone anchored hearing aid surgery: a retrospective analysis




ing the drilling procedure. The authors evaluated the osse-            tively, the results were in line with previously published
ointegration failure rate in MIPS and MMIT. In fact, failure           studies comparing MIPS and LT with tissue preservation.
rates were 35% for MIPS and 14.6% for MMIT; all of these               Moreover, the large sample size increases the statistical
cases were early osseointegration failures. The higher fail-           power and significance of the results.
ure rate of MIPS was related to the cannula to protect the
soft tissue during the drilling procedure. In fact, the can-           Conclusions
nula can interfere with both the irrigation during the drill-
ing phase and with the evacuation of the bone dust leading             LT with soft tissue preservation and MIPS demonstrate
to increased temperature in the surrounding bone. Moreo-               similar, good surgical outcomes in terms of skin reaction
ver, the same authors eventually abandoned both MIPS and               according to Holgers score during long lasting follow-up as
MMIT due to the poor implant survival rate compared with               well as equally good implant survival of 100%. Moreover,
LT with tissue preservation, ruling out tissue trapping as a           the present study shows that surgical mean time for MIPS
cause of failure 25.                                                   is shorter than the surgical time for LT with tissue preserva-
In the present study, no significant difference was found              tion.
between LT and MIPS in terms of skin reaction graded
by Holgers score, even though the mean follow-up dura-                 Acknowledgements
tion was longer for the LT group than for the MIPS group.
                                                                       Accepted for poster presentation at the 32nd Politzer So-
One patient from the LT group had a Holgers score of 3
                                                                       ciety Meeting/2nd World Congress of Otology; 28 May-1
at the first follow-up examination due to excessive band-
                                                                       June 2019 Warsaw, Poland.
age compression. There was mild skin inflammation with
tissue granulation around the wound in absence of abut-
ment pathological mobility. This case corroborates the hy-             References
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