The classical approach to middle ear surgery is microscopic technique.1,2 Operating microscopes have been used dated from mid-20thcentury.3,4 At the beginning, microscopes were utilized in limited number of middle ear surgery like tympanoplasty and ossiculoplasty.1–3 Over time, with the reciprocal evolvement of microscopes and surgical techniques, the use of microscopes in every type of otologic surgery becomes indispensable. On the other side utilization of endoscopes as the main approach for middle ear surgery is relatively novice.5–7 At the beginning, the endoscopes had been used only for diagnostic purposes or assistance in microscopic middle ear surgery.8,9 But nowadays even the whole surgical process could be carried out solely by endoscopic approach. Endoscopes have been used in various types of ear surgeries also including the ossiculoplasty. With the ever-increasingly use of endoscopes in almost every type of otologic surgery, as a matter of cause some questions emerged concerning the feasibility and reliability of endoscopes.

Many classifications have been proposed for tympanoplasty and ossiculoplasty. Wullstein published the 1st classification of tympanoplasty including details of middle ear surgery and ossiculoplasty in 1956.10 Next, the original classification was modified on several occasions by Lierle,11 Farrior,12 Belluci,13 Pratt,14 Nadol and McKenna,15 respectively. On the other hand, McGee and Hough16 have defined a novel classification focusing mainly on ossiculoplasty which was then generally accepted. The classification of McGee and Hough also was preferred in this study.

There is an ongoing dispute concerning the need and feasibility of endoscopic approach in ear surgery. But two obstacles seem to leap out in comparing the microscopic and endoscopic approach. At first, there are numerous types of different surgical techniques of ossiculoplasty complicating the comparison of two approaches. The latter one is the existence of different ossiculoplasty classifications which also hampers the comparison of both approaches throughout different studies.

There are limited number of studies comparing the both approaches particularly in terms of ossiculoplasty.17–19 In this study, we aimed to reveal the effect of the surgical approach (microscopic and endoscopic) on the functional results of ossiculoplasty while considering two subtypes.

In the current study, we did not find any statistically significant difference in terms of ACG, pre- and postoperative ABG between two approaches. The pre- and postoperative ABGs were found to be similar between the two groups for both ossiculoplasty types. This homogeneity of ABGs throughout groups increases the reliability of our results. It should also be noted here that the main indicator of functional success is ACG, which was found to be similar in both approaches, regardless of the ossiculoplasty type (Fig. 5, Fig. 6). Comparison of tympanic membrane perforation with regard to size and localization did not reveal any significant statistical difference (Table 3). This finding can be accepted as a factor against possible group selection bias. Considering these findings, it can be asserted that endoscopic type-II and type-III ossiculoplasty is just as effective as the microscopic approach. In other words, type of ossiculoplasty has no effect on the functional outcome of either approach.

There are numerous clinical studies evaluating microscopic and endoscopic approach in terms of outcomes. Considering the design of these studies, basically two different research designs stand out. Namely, in most of the studies5,6,9,22–27 outcomes of only one approach (microscopic or endoscopic) were evaluated solely, while in remaining fewer studies both approaches are compared in a controlled clinical research design.28–30 On the other hand, number of studies which particularly evaluate the functional outcome of “endoscopic ossiculoplasty” is very limited.17–19 As far as we know, the only randomized control trial focusing on endoscopic ossiculoplasty was done by Das et al.18 They compared functional outcome of TORP and PORP in terms of approach (microscopic and endoscopic). Conspicuously, they revealed a significant better ACG in endoscopic group when compared with the microscopic group particularly in the PORP series. But the long term ACG in both approaches for both (TORP and PORP) prosthesis did not differ significantly. The results of the current study are concordant with the study of Das et al. But our study differs in some respects. We constituted the subgroups according to the type of ossiculoplasty as type-II and type-III rather than the type of prosthesis. Thereby, unlike the study of Das et al., other reconstruction methods like incus interposition and bone cement utilization have also been included in the subgroups. Besides, in the study of Das et al., cases with additional pathologies had not been excluded.18 In contrast with the current study, they had included cases with cholesteatoma and retraction pockets which might affect functional outcome in favor of one approach. It is apparent that every additional manipulation or drilling for retraction pocket and/or cholesteatoma would have impact on the eventual status of the ossicular chain. Another study done by Calowey et al.19 was designed comparable to our study in terms of subgroups. Namely, they also included incus interposition and bone cement utilization. Besides, their study was also retrospective just like the current one. But there was a main difference that their study was on pediatric cases below the age of 18. Nevertheless, they also failed to reveal any significant difference between both approaches and both ossiculoplasty techniques in terms of ACG. Besides, Yawn et al.17 also found no significant difference in ACG between both approaches. But they included cases with mastoidectomy, cholesteatoma and recurrent surgery which are defined as exclusion criteria in the current study. They had preferred microscopic approach when middle ear pathology (cholesteatoma, etc.) extend beyond the horizontal semicircular canal. It is apparent that these factors would lead selection bias in favor of endoscopic approach.

To the best of our knowledge, the only meta-analysis on studies comparing endoscopic and microscopic ossiculoplasty was done by Tsetsos et al.31 After a comprehensive search and analyses of three hundred twenty eighth studies they ended up only with 3 eligible studies which are also reviewed above.17–19 Tsetsos et al. concluded that endoscopic approach is at least as feasible as microscopic approach. Our study differs from the previous ones in such a way that we paid regard to the peroperative status of the ossicular chain rather than the type of graft or prosthesis for subgroup classification. In other words, we constituted the subgroups according to the type of ossiculoplasty as type-II and type-III rather than the type of prosthesis.

In both endoscopic and microscopic ossiculoplasty, the reconstruction methods are the same; namely the type of graft and prosthesis, incisions, flap elevations, placement of the reconstruction material etc. does not differ. Thus, one might not expect a significant difference in overall outcome. On the other hand, ossiculoplasty necessitates very delicate manipulation of ossicles. For this reason, some other factors which differ between two approaches might affect particularly the functional outcome. Hence, if there is any difference in functional outcome, it can be linked up to other factors such as depth of field, number of hands in use and heat exposure which are evaluated previously in numerous studies.32 There are some advantages of endoscopic approach particularly in ossiculoplasty. It provides better and closer visualization of the ossicles, oval window and surrounding microanatomical landmarks.33 On the other side, the microscopic approach comes to the fore with the absence of thermal injury and the ability to use both hands.34 It seems that all these factors counter acts and ultimately countervails the functional outcome for both approaches.

Our study has certain limitations. First, it was not possible to totally avoid selection bias due to the retrospective design. To partially forestall this bias, we compare both groups in terms of other clinical factors like preoperative ABG and status of the tympanic membrane. We also excluded cases with additional pathologies (presence of cholesteatoma and retraction pocket) apart from ossicular chain pathologies which might hamper the functional outcome in favor of one approach. In addition, cases with postoperative graft failure were excluded for the detection of exact functional success achieved solely by ossiculoplasty. The second limitation was the lack of early (< 6 months) and late term (>1 year) audiometric results. Audiometric data at one year could be obtained completely which reflects the mid-term functional status sufficiently.

There are limited number of studies regarding impact of approach on functional outcome of different ossiculoplasty types which all have their distinctive limitations.17–19 Similarly, we investigated the impact of approach on functional outcome in terms of ossiculoplasty type. But our study dissociates from the previously mentioned three studies in that we payed regard to the peroperative status of the ossicular chain rather than the type of graft or prosthesis.

In the last instance, it would be appropriate to take into account anatomic characteristics, habitude of the surgeon and duration of the surgery rather than the functional outcome when deciding the type of approach.

The current study revealed that endoscopic approach both in type-II and type-III ossiculoplasty is at least reliable as microscopic approach regarding ACG and postoperative ABG.

Data will be made available on request.

This retrospective research was approved by the Health Sciences Ethics Committee of Manisa Celal Bayar University (21/05/2021/20478486-800) and records Hafza Sultan Hospital was utilized.

The authors declare no conflicts of interest.