Bone cement repair of malleus handle fractures: Intraoperative video and case report of two patients.

Isolated malleus fractures are a rare occurrence with few reported cases in the literature. Symptoms include sudden otalgia, hearing loss, tinnitus and aural fullness. Work-up and diagnosis are based on a combination of thorough anamnesis and careful otoscopic evaluation or high-resolution computer tomography. We present two cases of isolated malleus handle fractures who were diagnosed based on a combination of pneumatic otoscopy and tympanometry. Both fractures were surgically repaired using hydroxyapatite bone cement as showcased in the supplemental video material. Post-operative audiometry showed improvement in the pure-tone-average of both patients as well as normalisation of tympanometry. Isolated malleus fracture should be suspected in cases of sudden hearing loss and tinnitus following digital manipulation of the outer ear canal together with a conductive hearing loss with a mostly high-frequent air-bone-gap and hypercompliant tympanometry with hypermobility of the tympanic membrane on pneumatic insufflation. Surgical repair of the fracture using bone cement has good hearing outcomes and leads to improvement in auditory symptoms.

Exclusive endoscopic management of incus long process major defects: conventional incus interposition versus malleostapediopexy.

PURPOSE: The aim of the current study is to compare the surgical and audiometric results of conventional incus interposition (IP) versus malleostapediopexy (MS) in incus long process large defects. METHODS: A total of 71 patients (incus IP group n = 37, MS group n = 34) were enrolled in this study. All patients enrolled in the current study underwent ossiculoplasty via an exclusive endoscopic transcanal approach. Pre- and postoperative audiometric measurements and air-bone gap (ABG) values were compared, and if the postoperative ABG value was less than 20 dB, ossiculoplasty was considered successful. Graft success rates and complications were also compared. RESULTS: The average auditory gain was 14.7 ± 4.2 dB in the incus IP group and 18.3 ± 5.1 dB in the MS group. The auditory gain was significantly greater in the MS group relative to the incus IP group (p = 0.012). Ossiculoplasty success (postoperative ABG value < 20 dB) rate was 70.3% in the incus IP group patients and 88.2% in the MS group patients (p < 0.001). There was no significant difference in terms of graft success rate between groups (p > 0.05) and the overall graft uptake rate was 91.5% (65/71). CONCLUSION: Malleostapediopexy-bridging of malleus and stapes using bone cement-is an effective, reasonable, and more efficient technique in terms of auditory outcomes relative to the conventional incus interposition in endoscopic transcanal management of incus long process major defects.

Registration of preoperative temporal bone CT-scan to otoendoscopic video for augmented-reality based on convolutional neural networks.

PURPOSE: Patient-to-image registration is a preliminary step required in surgical navigation based on preoperative images. Human intervention and fiducial markers hamper this task as they are time-consuming and introduce potential errors. We aimed to develop a fully automatic 2D registration system for augmented reality in ear surgery. METHODS: CT-scans and corresponding oto-endoscopic videos were collected from 41 patients (58 ears) undergoing ear examination (vestibular schwannoma before surgery, profound hearing loss requiring cochlear implant, suspicion of perilymphatic fistula, contralateral ears in cases of unilateral chronic otitis media). Two to four images were selected from each case. For the training phase, data from patients (75% of the dataset) and 11 cadaveric specimens were used. Tympanic membranes and malleus handles were contoured on both video images and CT-scans by expert surgeons. The algorithm used a U-Net network for detecting the contours of the tympanic membrane and the malleus on both preoperative CT-scans and endoscopic video frames. Then, contours were processed and registered through an iterative closest point algorithm. Validation was performed on 4 cases and testing on 6 cases. Registration error was measured by overlaying both images and measuring the average and Hausdorff distances. RESULTS: The proposed registration method yielded a precision compatible with ear surgery with a 2D mean overlay error of 0.65 ± 0.60 mm for the incus and 0.48 ± 0.32 mm for the round window. The average Hausdorff distance for these 2 targets was 0.98 ± 0.60 mm and 0.78 ± 0.34 mm respectively. An outlier case with higher errors (2.3 mm and 1.5 mm average Hausdorff distance for incus and round window respectively) was observed in relation to a high discrepancy between the projection angle of the reconstructed CT-scan and the video image. The maximum duration for the overall process was 18 s. CONCLUSIONS: A fully automatic 2D registration method based on a convolutional neural network and applied to ear surgery was developed. The method did not rely on any external fiducial markers nor human intervention for landmark recognition. The method was fast and its precision was compatible with ear surgery.

[An unusual case: fracture of the handle of the malleus due to finger manipulation]. / Ein ungewöhnlicher Fall: Fraktur des Hammergriffs durch Fingermanipulation.

An isolated fracture of the handle of the malleus is a rare entity in otorhinolaryngology and manifests clinically as acute-onset unilateral hearing loss. Several factors may cause this injury, including acute barotraumatic pressure changes or traumatic events. Various therapeutic approaches such as tympanoplasty, autologous graft, or application of bone cement are discussed. We report the case of a 46-year-old female patient who developed acute hearing loss in her left ear after finger manipulation. Clinical evaluation revealed axial displacement of the handle of the malleus and audiometry indicated conductive hearing loss. After otoscopy, audiometry, and computed tomography, tympanoscopy was indicated due to suspicion of ossicular chain disruption. Intraoperatively, an isolated fracture of the handle of malleus was found, which was treated with glass ionomer cement. Following postoperative examination, there was progressive improvement in the acoustic transmission component, such that a normal hearing threshold was observed 4 months postoperatively. This case report underlines the importance of precise diagnosis and individualized treatment for rare middle ear injuries.

A novel technique in treatment of advanced tympanosclerosis: results of malleus replacement and loop prostheses combination; pure endoscopic transcanal approach.

PURPOSE: The objectives of the present clinical trial are to describe our surgical technique for advanced tympanosclerosis (TS) and to present the comparison of pre-and postoperative audiometric results. METHODS: 21 patients suffering from advanced TS (Only type III and IV patients according to Wielinga-Kerr classification) were enrolled in this prospective study. A pure transcanal endoscopic approach was preferred for all patients included in the study. Titanium malleus replacement prosthesis (MRP) and polytetrafluoroethylene (PTFE) loop prosthesis combination were used to bypass fixed ossicles to achieve sound transmission to the inner ear. Pre-and postoperative pure tone audiometry (PTA) measurements and air-bone gap (ABG) results compared, and surgical technique was considered successful if postoperative ABG was less than 20 dB. RESULTS: Six of the 21 patients had been operated on before and the tympanic membrane (TM) was intact. The remaining 15 of the 21 patients were the primary cases, and TM perforation repair and ossiculoplasty using combination of the MRP and PTFE loop prosthesis were performed at single-staged operation. The average preoperative ABG values significantly improved from 37.1 ± 6.2 to 14.5 ± 1.2 dB postoperatively (p < 0.001). The mean preoperative air conduction threshold (ACT) significantly decreased from 51.7 ± 11.4 to 28.5 ± 9.1 dB (p < 0.001). CONCLUSION: TS surgery is still a controversial issue particularly in stapes footplate fixation. However, our surgical and audiological results in this study are quite promising. The combination of titanium MRP and PTFE loop prosthesis for restoring sound transmission in advanced TS cases is reliable, effective and novel treatment option via endoscopic transcanal approach.

Morphological variations in malleus among the male and female.

OBJECTIVE: To determine gender-based morphological variations in malleus. METHODS: The cross-sectional descriptive study was conducted at the Ear-Nose-Throat and Radiology departments of a public-sector hospital in Karachi, from January 20 to July 23, 2021, and comprised subjects of either gender aged 10-51 years who had intact ear ossicles. They were divided into equal male and female groups. After history and a thorough examination of the ear, high-resolution computed tomography scan of petrous temporal bone was done. The images were studied for malleus, to measure the parameters of its head width, length and shape of manubrium, and total length of malleus for possible morphological variations along gender lines. Data was analysed using SPSS 23. RESULTS: Of the 50 subjects, 25(50%) were males with mean width of the head 3.04±0.34mm, mean length of manubrium 4.47±0.48mm, and mean total length of malleus 7.76±0.60mm. The corresponding values in 25(50%) females were 3.00±0.28mm, 4.31±0.45mm and 7.41±0.51mm. The total length of malleus between both genders was significantly different (p= 0.031). The shape of manubrium was straight in 10(40%) males and 8(32%) females, and curved in 15(60%) males and 17(68%) females. CONCLUSIONS: Width of head, length of manubrium and total length of malleus were different in gender terms, but the total length of malleus was significantly different.

Region-specific endodermal signals direct neural crest cells to form the three middle ear ossicles.

Defects in the middle ear ossicles - malleus, incus and stapes - can lead to conductive hearing loss. During development, neural crest cells (NCCs) migrate from the dorsal hindbrain to specific locations in pharyngeal arch (PA) 1 and 2, to form the malleus-incus and stapes, respectively. It is unclear how migratory NCCs reach their proper destination in the PA and initiate mesenchymal condensation to form specific ossicles. We show that secreted molecules sonic hedgehog (SHH) and bone morphogenetic protein 4 (BMP4) emanating from the pharyngeal endoderm are important in instructing region-specific NCC condensation to form malleus-incus and stapes, respectively, in mouse. Tissue-specific knockout of Shh in the pharyngeal endoderm or Smo (a transducer of SHH signaling) in NCCs causes the loss of malleus-incus condensation in PA1 but only affects the maintenance of stapes condensation in PA2. By contrast, knockout of Bmp4 in the pharyngeal endoderm or Smad4 (a transducer of TGFß/BMP signaling) in the NCCs disrupts NCC migration into the stapes region in PA2, affecting stapes formation. These results indicate that region-specific endodermal signals direct formation of specific middle ear ossicles.

Internal vascular channel architecture in human auditory ossicles.

The vascular supply of the human auditory ossicles has long been of anatomical and clinical interest. While the external blood supply has been well-described, there is only limited information available regarding the internal vascular architecture of the ossicles, and there has been little comparison of this between individuals. Based on high-resolution micro-CT scans, we made reconstructions of the internal vascular channels and cavities in 12 sets of ossicles from elderly donors. Despite considerable individual variation, a common basic pattern was identified. The presence of channels within the stapes footplate was confirmed. The long process of the incus and neck of the stapes showed signs of bony erosion in all specimens examined. More severe erosion was associated with interruption of some or all of the main internal vascular channels which normally pass down the incudal long process; internal excavation of the proximal process could interrupt vascular channels in ossicles which did not appear to be badly damaged from exterior inspection. An awareness of this possibility may be helpful for surgical procedures that compromise the mucosal blood supply. We also calculated ossicular densities, finding that the malleus tends to be denser than the incus. This is mainly due to a lower proportion of vascular channels and cavities within the malleus.

Micro-CT of the human ossicular chain: Statistical shape modeling and implications for otologic surgery.

The ossicular chain is a middle ear structure consisting of the small incus, malleus and stapes bones, which transmit tympanic membrane vibrations caused by sound to the inner ear. Despite being shown to be highly variable in shape, there are very few morphological studies of the ossicles. The objective of this study was to use a large sample of cadaveric ossicles to create a set of three-dimensional models and study their statistical variance. Thirty-three cadaveric temporal bone samples were scanned using micro-computed tomography (µCT) and segmented. Statistical shape models (SSMs) were then made for each ossicle to demonstrate the divergence of morphological features. Results revealed that ossicles were most likely to vary in overall size, but that more specific feature variability was found at the manubrium of the malleus, the long process and lenticular process of the incus, and the crura and footplate of the stapes. By analyzing samples as whole ossicular chains, it was revealed that when fixed at the malleus, changes along the chain resulted in a wide variety of final stapes positions. This is the first known study to create high-quality, three-dimensional SSMs of the human ossicles. This information can be used to guide otological surgical training and planning, inform ossicular prosthesis development, and assist with other ossicular studies and applications by improving automated segmentation algorithms. All models have been made publicly available.

Multi-operated cholesteatoma: when two surgeries are not enough.

PURPOSE: Most studies regarding residual and recurrent cholesteatoma focus on single relapse. This study examines patients who had to undergo at least three surgeries for complete eradication of their cholesteatoma, with the aim of bringing to light risk factors and assessing the functional impact of multiple surgeries on hearing. METHOD: We include 27 patients who underwent 3 consecutive surgeries for cholesteatoma between 2006 and 2016. This population represented 3.1% of all cholesteatoma operated on during that same period (868 patients). RESULTS: Cases of multi-residual and/or recurrent cholesteatoma (RRC) were significantly younger (13.1 years old), than single-RRC or cases with No-RRC (respectively, 28.0 and 38.5 years old) (p < 0.01). Furthermore, there was a significant difference in cholesteatoma location especially for combined attical and mesotympanic location between the three groups (no-RCC 26%; single-RRC 34% and multi-RRC 66%) (p < 0.01). There was also a significant difference in ossicular erosion of the malleus, incus and stapes between the three groups (p < 0.01). In our study, the type of surgery did not influence multi-RRC rates. We did not observe any significant impact on hearing between the first and third surgeries. Mean duration between the first and second surgeries was significantly shorter for multi-RRC (14.5 months SD 8.3) than for single-RRC (23.3 months SD 18.1) (p < 0.05). CONCLUSION: Special care should be given in case of combined attical and mesotympanic extension, ossicular erosion and young children. Delaying the realization of MRI, and/or of second-look surgery, could decrease the risk of multi-RRC.

Navigational guidelines and positional relationships of the human auditory ossicles from three-dimensional topography for ensuring safe and effective malleostapedotomy : Stereotactic topography of the auditory ossicles and its clinical implication.

PURPOSE: The aims of the present study were to identify detailed positional relationship between the auditory ossicles and to provide theoretic navigational guidelines for optimal prosthesis adaptation and effective malleostapedotomy. METHODS: Fifty sides of the temporal bone from donated cadavers were scanned by MicroCT and the malleus, incus, stapes and tympanic membrane were materialized three dimensionally using computer software. Dimensions between the auditory ossicles closely related to malleostapedotomy were measured twice. RESULTS: The grip site of malleus handle was mean 1.8 mm superior and mean 1.3 mm anterior, and linear distance between the grip site of malleus handle and the footplate of the stapes was mean 6.5 mm. The stapes was not parallel to the tympanic membrane and rotated mean 10.7° posteriorly relative to the tympanic membrane. CONCLUSION: Surgeons should start with at least 8.75 mm prosthesis to cover the upper limits of potential anatomy and then trim down to the individualization to the case. The ideal loop morphology has to be oval shape more than 1.4 mm in the long diameter and 1.0 mm in the short diameter. The wire of the prosthesis has to be bended at the two points: about 10° anteriorly at the most proximal point of the wire and about 50° superiorly at the stapes head point.

[Application of 10 µm otology CT on evaluation of isolated malleus fixation in patients with conductive hearing loss].

Objective: To evaluate the application of 10 µm otology CT on evaluation of isolated malleus fixation (IMF) in patients with conductive hearing loss. Methods: A total of 19 patients (25 sides) with idiopathic hearing loss, including 8 males and 11 females, aged between 4 to 50 years, who underwent 10 µm otology CT examination in Department of Radiology, Beijing Friendship Hospital, Capital Medical University from October 2020 to July 2021, were retrospectively collected. For those patients with idiopathic hearing loss, there were 5 cases (6 sides), including 2 males and 3 females, with an average age of 18-70 [65(20,68)] years, with bony connection between malleus and tympanum wall. Eighteen sex-and age-matched cases with normal hearing group, including 6 males and 12 females, with an average age of 20-68 (39±14) years, as the ratio of 1∶3, were included as the controls. The distances of the tegmen tympani between malleus head and horizontal semicircular canal, as well the distances between malleus head and horizontal semicircular canal were retrospectively measured and further compared between the two groups. Results: The incidence of IMF in patients with idiopathic conductive hearing loss without other etiologies was 24.0% (6/25). The specificity of 10 µm otology CT in diagnosing IMF was 100%. The distances of tegmen tympani between horizontal semicircular canal and malleus head in IMF patients were significantly smaller compared with the controls [-0.65(-1.21, -0.35) mm vs 1.34(0.04, 1.68) mm;0.92(0.51, 1.49) mm vs 2.82(1.76, 3.53) mm](both P<0.05, respectively). There was no significant difference in distances between malleus head and horizontal semicircular canal [-1.30 (-1.90, -0.46)mm vs -0.42 (-1.15, 0.05),P=0.057]. Conclusions: IMF is not uncommon in conductive hearing loss without other causes, which can be clearly shown by 10 µm otology CT. Its occurrence is related to the local downward shift of tegmen tympani above the malleus, without upwards displacement of the malleus.

[Analysis of spatial location of the malleus in patients with chronic otitis media based on 10 µm otology CT].

Objective: To assess the changes of the spatial location of the malleus in patients with chronic otitis media (COM) using 10 µm otology CT. Methods: Forty-five patients with COM (COM group, 45 ears) and 55 patients without external and middle ear disease (control group, 89 ears), who underwent 10 µm otology CT examination in Department of Radiology, Beijing Friendship Hospital, Capital Medical University from October 2020 to March 2021, were retrospectively collected during the same period. In the COM group, there are 20 males and 25 females, aged from 20 to 78 (40±14) years. In the control group, 29 were males and 26 were females, with age of 19 to 57 (32±11) years. The shortest distance between the malleus head and the upper wall, the distance between the outer edge of the malleus neck and the scutum, the distance between the outer edge of the malleus neck and the pars flaccida of the tympanic membrane, the shortest distance between the malleus head and the anterior wall, the shortest distance between the anterior process and the anterolateral wall, the shortest distance between the tip of the malleus handle and the promontory, and the shortest distance between the malleus head and the tympanic segment of the facial nerve were measured and compared between the two groups. Results: Compared with the control group, the head-upper wall distance (M (Q1, Q3)) (0.81 (0.48, 1.21) mm vs 0.57 (0.33, 0.90) mm) and the neck-scutum distance (1.79 (1.54, 2.13) mm vs 1.65 (1.48, 1.83) mm) were larger in the COM group (all P<0.05), and the neck-tympanic membrane distance (1.32 (1.15, 1.49) mm vs 1.45 (1.31, 1.59) mm) and the handle-promontory distance (1.56 (1.33, 2.09) mm vs 2.10 (1.74, 2.43) mm) were reduced in the COM group (all P<0.05, respectively). The neck-tympanic membrane distance on the left was larger than those on the right in the COM group (1.39 (1.19, 1.51) mm vs 1.21 (0.87, 1.31) mm, P<0.05). Conclusion: There are changes in the relative position of the malleus in patients with COM, which are helpful for further understanding the imaging manifestations in patients with COM.

[Numerical study on the effect of middle ear malformations on energy absorbance].

In order to study the effect of middle ear malformations on energy absorbance, we constructed a mechanical model that can simulate the energy absorbance of the human ear based on our previous human ear finite element model. The validation of this model was confirmed by two sets of experimental data. Based on this model, three common types of middle ear malformations, i. e. incudostapedial joint defect, incus fixation and malleus fixation, and stapes fixation, were simulated by changing the structure and material properties of the corresponding tissue. Then, the effect of these three common types of middle ear malformations on energy absorbance was investigated by comparing the corresponding energy absorbance. The results showed that the incudostapedial joint defect significantly increased the energy absorbance near 1 000 Hz. The incus fixation and malleus fixation dramatically reduced the energy absorbance in the low frequency, which made the energy absorbance less than 10% at frequencies lower than 1 000 Hz. At the same time, the peak of energy absorbance shifted to the higher frequency. These two kinds of middle ear malformations had obvious characteristics in the wideband acoustic immittance test. In contrast, the stapes fixation only reduced the energy absorbance in the low frequency and increased energy absorbance in the middle frequency slightly, which had no obvious characteristic in the wideband acoustic immittance test. These results provide a theoretical reference for the wideband acoustic immittance diagnosis of middle ear malformations in clinic.

[Isolated malleus handle fracture: cases report and literature review]. / Izolirovannyi perelom rukoyatki molotochka. Obzor literatury i klinicheskie sluchai.

The isolated malleus handle and neck fractures are rare pathology which demands detailed diagnosis and individual treatment plan in every case. Sometimes it could heal without surgery, but in most part of cases surgical treatment is indicated. The short literature review and 2 clinical cases of this pathology are presented in this article. We describe our own variants of surgery repair with autologous cartilage with good results.

Comparison of sheep and human middle-ear ossicles: anatomy and inertial properties.

The sheep middle ear has been used in training to prepare physicians to perform surgeries and to test new ways of surgical access. This study aimed to (1) collect anatomical data and inertial properties of the sheep middle-ear ossicles and (2) explore effects of these features on sound transmission, in comparison to those of the human. Characteristic dimensions and inertial properties of the middle-ear ossicles of White-Alpine sheep (n = 11) were measured from high-resolution micro-CT data, and were assessed in comparison with the corresponding values of the human middle ear. The sheep middle-ear ossicles differed from those of human in several ways: anteroinferior orientation of the malleus handle, relatively small size of the incus with a relatively short distance to the lenticular process, a large area of the articular surfaces at the incudostapedial joint, and a relatively small moment of inertia along the anterior-posterior axis. Analysis in this study suggests that structure and orientation of the middle-ear ossicles in the sheep are conducive to an increase in the hinge-like ossicular-lever-action around the anterior-posterior axis. Considering the substantial anatomical differences, outcomes of middle-ear surgeries would presumably be difficult to assess from experiments using the sheep middle ear.

The discomallear ligament: anatomical, microscopical, and radiologic analysis.

BACKGROUND: Several anatomic relationships between the ear and the temporo-mandibular joint have been proposed to account for the presence of tinnitus during temporo-mandibular disorders. Among the otomandibular structures, the discomallear ligament (DML) is interposed between the malleus and the retrodiscal capsular complex. The aim of present paper was to study through dissection the frequency and morphology of DML, to characterize its type of collagen, and to evaluate the DML on routine computed tomography (CT). METHODS AND RESULTS: The study has been conducted on five un-embalmed adult cadavers, and in all cases, the DML was present (100%). It was constituted mainly by fibers of collagen I, with abundant elastic fibers. On CT exams of 40 patients with no reported pathology of the ear, on axial images, a dense structure, going from the upper end of the petrotympanic fissure to the neck of the malleus, was present in all the cases. In 90%, it showed a triangular shape, in 5% a rectangular shape, and in 5% a curved course. The mean length of the antero-medial side was 2 ± 0.6 mm and that of the antero-lateral side was 1.63 ± 0.5, and the mean area was 1.29 ± 0.83 mm2. CONCLUSION: The DML could represent an anatomical structure that joining the temporo-mandibular joint and the malleus may play a role in the otologic symptoms during temporo-mandibular disorders.

Pars tensa and tympanicomalleal joint: proposal for a new anatomic classification.

PURPOSE: The tympanic membrane (TM) belongs to the ear. Despite its place in the ear anatomy, can we give it also a different anatomic classification? The main objective is to clarify the nature of TM, tympanic bone and malleus to propose a new anatomic classification. METHODS: This cadaveric study was performed in two human heads and six fresh temporal bones. A study of the temporomandibular joint, external acoustic meatus (EAM), TM and middle ear structures was conducted. A medical literature review englobing anatomy, embryology, histology and phylogeny of the ear was performed and the results were compared with the results of the dissection. RESULTS: The external ear is constituted by the auricle and the EAM. This last segment is made by a cartilaginous and an osseous portion. The osseous portion of the EAM is constituted mainly by tympanic bone. The external ear is separated from the middle ear by the TM. Inside the middle ear, there are three ossicles: malleus, incus and stapes, which allow the conduction of sound to the cochlea. Based on the anatomic dissection and medical literature review of the tympanic bone, malleus and TM, we propose that these structures are interconnected like a joint, and named it "Tympanicomalleal joint". CONCLUSIONS: It seems that the TM can be part of a joint that evolved to improve sound transmission and middle ear protection. Thinking TM has part of a joint may help in the development of more efficient reconstructive surgical techniques.

Ossicular chain defects in adults with chronic otitis media.

BACKGROUND AND OBJECTIVE: Chronic otitis media (COM) is a common condition characterized by the perforation of the tympanic membrane and inflammation of the mucosal lining the hollow space in the middle ear and airy spaces of the temporal bone for at least 2-6 week. This study was carried out to find out the status of the middle ear ossicles in patients with COM and to correlate their status with clinical parameters. METHODS: This retrospective clinical study was conducted on 107 COM patients (52 males and 55 females; age range: 18 to 75 years) submitted to surgery in the Otology Clinic at Imam Khomeini Hospital, Ahvaz Jundishapur University of Medical Sciences, Iran. Initially, a comprehensive case-history was obtained from patients and their hearing thresholds were recorded. Then, ossicles status and their junction condition were evaluated intraoperatively. RESULTS: The malleus was found intact in 70 (65.42%), absent in 10 (9.34), and eroded in 27 (25.24%) patients. Our results revealed that the incus was intact in 33 (30.84%), eroded in 55 (51.41%) and absent in 19 (17.75%) subjects. Stapes was found intact in 54 (50.46%) cases and eroded in 53 (49.54%) cases. The mean Pure Tone Average (PTA) and Air-Bone Gap (ABG) comparisons in "intact" and "discontinuous" ossicular chain groups was not significant (Independent sample t-test, p>0.05). CONCLUSION: Our results demonstrated that incus was the most susceptible middle ear ossicle to erosion in COM, whereas the malleus was the most resistant ossicle. Furthermore, ABG and PTA values cannot be considered as a potential preoperative predictor for ossicular chain status.

Osteogenic capillaries orchestrate growth plate-independent ossification of the malleus.

Endochondral ossification is a developmental process by which cartilage is replaced by bone. Terminally differentiated hypertrophic chondrocytes are calcified, vascularized, and removed by chondroclasts before bone matrix is laid down by osteoblasts. In mammals, the malleus is one of three auditory ossicles that transmit vibrations of the tympanic membrane to the inner ear. The malleus is formed from a cartilaginous precursor without growth plate involvement, but little is known about how bones of this type undergo endochondral ossification. Here, we demonstrate that in the processus brevis of the malleus, clusters of osteoblasts surrounding the capillary loop produce bone matrix, causing the volume of the capillary lumen to decrease rapidly in post-weaning mice. Synchrotron X-ray tomographic microscopy revealed a concentric, cylindrical arrangement of osteocyte lacunae along capillaries, indicative of pericapillary bone formation. Moreover, we report that overexpression of Fosl1, which encodes a component of the AP-1 transcription factor complex, in osteoblasts significantly blocked malleal capillary narrowing. These data suggest that osteoblast/endothelial cell interactions control growth plate-free endochondral ossification through 'osteogenic capillaries' in a Fosl1-regulated manner.