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BACKGROUND AND HYPOTHESIS: Isolated malleus shaft fractures are rare cases. A commonly reported cause is a finger pulled out from a wet outer ear canal after a shower or bath. The objective was to investigate experimentally the mechanism and forces needed to establish an isolated malleus shaft fracture.

METHODS: Ten fresh-frozen human temporal bones were adapted to allow visual inspection of the structures involved while negative pressure trauma was applied. Thirty malleus bones were broken and the required forces were measured. Measurements from 60 adult test subjects were used to create mathematical and physical models to calculate and measure the forces necessary for generating trauma. To calculate the maximum muscle force developed by the tensor tympani muscle, the muscle area and fiber type composition were determined.

RESULTS: The temporal bone experiments showed that applied negative pressure in a wet ear canal could not fracture the malleus shaft with only passive counterforce from supporting structures, although the forces exceeded what was required for a malleus shaft fracture. When adding calculated counteracting forces from the tensor tympani muscles, which consisted of 87% type II fibers, we estimate that a sufficient force is generated to cause a malleus fracture.

CONCLUSION: The combination of a negative pressure created by a finger pulling outward in a wet ear canal and a simultaneous counteracting reflexive force by the tensor tympani muscle were found to be sufficient to cause an isolated malleus fracture with an intact tympanic membrane.

Objective: We compared the sound transmission using different types of total ossicular replacement prostheses (TORP); we then studied the performance of a new TORP that we designed inspired by the columella, the single ossicle found in birds.

Methods: Stapedial vibrations were measured on nine freshly frozen human temporal bones with laser Doppler vibrometry. We then compared the performances of eight common TORP positions or designs as well as the new silver prototype of bird-type prosthesis, designed also according to our digital holography patterns of the human tympanic membrane (TM).

Results: The TORPs placed in lateral contact with both the TM and the malleus handle outperformed, at most frequencies, those placed only in contact with the TM.

The new bird-type prosthesis performed equally well or better than all other prostheses.

Conclusion: If the malleus handle can be retained when placing a TORP, the best sound transmission can be achieved by placing the TORP in contact with both the distal part of the malleus handle and the TM. The good performance of our bird-type prosthesis suggests that there is still room for future improvement of prosthesis design to further optimize hearing outcomes after surgery.

Background: Patients with malleus fractures are described as rare in the literature. The cause of these fractures are most commonly trauma and digital manipulation of the ear canal, while in some cases the causes are unknown. At our clinic we record one new case every year, which leads to an incidence of approximately 40-50 new cases every year in Sweden. Different treatments have been proposed for this condition. However, since the condition is rare, no consensus has been reached regarding the best treatment. Additionally, it remains unclear whether malleus fractures can heal.

Aim: To get a deeper understanding of how malleus fractures occur, how they should be treated surgically, and if the malleus shows any sign of bone healing.

Materials and methods: Paper I. We carried out both a retrospective study of the medical records of nine Swedish patients with isolated malleus fractures, and a literature review of this condition. Symptoms, clinical findings and patients’ history were collected.Paper II. Ossiculoplasty on human temporal bones was performed in the presence of a malleus fracture. We developed a surgical model from freshly frozen human temporal bones, and we performed Laser Doppler vibrometry (LDV) measurements on this model both before and after ossiculoplasty.Paper III. We performed ossiculoplasties with different types of partial ossicular replacement prostheses (PORP) on human temporal bones and we measured the results with LDV.Paper IV. We performed an in vivo animal study on Merino sheep, in which we produced isolated malleus fractures. We then compared the bone healing of these fractures with that of the nasal bone and the mandible. Bone healing was detected with micro-CT.

Results: Paper I. The most common cause of isolated malleus fractures was found to be a so-called “digital” trauma, which occurred when the patients had removed a finger from the wet ear canal after bath. The hearing loss was occasionally accompanied by tinnitus and transient pain. Pneumatic otoscopy and tympanometry showed a hypermobile tympanic membrane, while audiometry showed a conductive hearing loss that increased towards higher frequencies.Paper II. Our LDV measurements indicated that fixation of an isolated malleus with bone cement may give the best results after surgery.Paper III. The best LDV measurements were obtained when ossiculoplasty was done using a PORP in lateral contact with both the tympanic membrane and the malleus handle.Paper IV. In our animal study we found no signs of bone healing at micro-CT four weeks after producing the malleus fractures. In contrast, both the nasal bone and the mandible showed bone healing. This indicates that the bone healing properties of the ossicles probably differ from those of other bones in the body.

Conclusion: Digital trauma is the major cause of isolated malleus fractures. Pneumatic otoscopy and tympanometry showed a hypermobile tympanic membrane, while audiometry showed a conductive hearing loss increasing towards the higher frequencies. We developed a method to employ freshly frozen human temporal bones and we used LDV for detecting optimal results. This method allows to evaluate and develop otosurgery, aimed to restore hearing after an interrupted ossicular chain. The animal study indicates that malleus fractures will not heal spontaneously.

Case report: We report Gudair (R) vaccination (against ovine Johne's disease, Mycobacterium avium subsp. paratuberculosis) site reactions in sheep used as a surgical model in biomedical research and discuss the actual and potential impact these lesions may have on surgical procedures, particularly in otology. Nine female Merino-cross sheep (Ovis aries) were enrolled in a project designed to investigate the healing capabilities of the malleus bone in the middle ear. The sheep were 12-18 months of age. Eight sheep had lesions near the base of the right ear that were discovered when surgery was performed. The size of the lesions varied and all lesions had a thick capsule containing various amount of caseous material. Two lesions had a draining tract where purulent material was apparent at the lowest point. The prescapular lymph nodes were not palpable in any of the sheep. Aerobic growth of various organisms was reported from four sheep lesions when the purulent material was transferred to a broth media. Histopathological examination revealed intralesional Mycobacteria and focal caseous necrosis or granulomatous dermatitis and cellulitis in seven of the eight lesions. Mild necrotising to granulomatous dermatitis and cellulitis was described in the lesion where organisms were not found. Conclusions: The lesions were confirmed at the end of the study to be associated with the vaccination and did not cause any known adverse effects on the research. However, it is important to acknowledge the risk of contamination these lesions could have on a sterile surgical site.

Objective: To compare stapes vibrations in different partial ossicular replacement prosthesis (PORP) applications.

Methods: Stapedial vibrations were measured on fresh frozen human temporal bones with laser Doppler vibrometry. Eight different types of common ossiculoplasty methods were compared regarding recovery of stapes vibrations in relation with the normal ossicular chain. The PORPs were divided into three groups: 1) PORPs with the lateral contact only with the tympanic membrane, 2) PORPs with lateral contact only to the malleus handle, and 3) PORPs with lateral contact with both the malleus handle and the tympanic membrane.

Results: The PORPs with lateral contact only to the malleus handle performed better than the PORPs with lateral contact to the tympanic membrane only at 2 kHZ, but the best recovery was found in the group with contact both to the malleus handle and the tympanic membrane.

Conclusion: The best sound transmission might be achieved by placing a PORP in contact with both the tympanic membrane and the handle of the malleus.

Hypothesis: In the literature several surgical methods have been reported that aim to improve hearing in patients with isolated malleus fractures; however, it is still not clear which method gives the best results.

Background: In this study, laser Doppler vibrometry (LDV) was used to compare the outcome of different surgical methods on malleus fractures in fresh frozen human temporal bones.

Methods: Fractured malleus shafts of defrosted human temporal bones were repaired with bone cement, with a malleus prosthesis from cortical bone, or with a partial ossicular replacement prosthesis (PORP) from cortical bone, and LDV measurements were obtained for analysis.

Results: The best result was achieved with the bone cement only, applied directly at the site of the fracture. The malleus prosthesis and the PORP gave similar results.

Conclusion: All three surgical methods gave good results, but when the distal end of the fractured malleus can be attached close to the proximal end, the technique using only cement tends to be the best option. If the parts are too far apart, a malleus prosthesis or a PORP would be good options.

AIM: To examine if a Gelfoam® plug in combination with surgical removal of the perforation edges could be an alternative to the widely accepted fat plug treatment for smaller ear drum perforations.

MATERIALS AND METHODS: A prospective study of 17 consecutive patients with persistent small ear drum perforations considered for myringoplasty. The perforations were central perforations 2 to 4 mm in diameter. Patient ages ranged from 6 to 83 years, and the operation was performed under general anesthesia with mask ventilation in children and under topical local anesthesia in adults. A Gelfoam® plug was inserted into the perforation after surgical removal of the perforation edges. The follow-up time was more than 3 months.

RESULTS: The closure rate of the ear drum was 83% (15/18). Pure tone average (PTA) was 19 dB preoperatively and 16 dB postoperatively.

CONCLUSIONS: We show for the first time in humans that a Gelfoam® plug in combination with surgical removal of the perforation edges seems to result in about the same closure rate as the fat plug technique in persistent small ear drum perforations. Moreover, the method using Gelfoam® is simpler and faster than the fat plug technique. We suggest that randomized studies comparing the Gelfoam® plug technique with the fat plug technique should be performed.

We report the investigation of the cause of isolated malleus fractures based on four recent patients at our clinic and five patients reported to us by Swedish otosurgeons. In recent years we have treated four patients with isolated malleus fractures. Colleagues in the Swedish Society of Otosurgeons were encouraged to send us reports on patients with diagnosed isolated malleus fractures, resulting in five more cases. A literature review focusing on the cause and management of this injury was also conducted. Eight of nine patients in the Swedish material had the same history. The patients had inserted a finger into the external auditory canal (most often after a bath) and then pulled it out. Immediately afterwards they experienced a short pain and a hearing loss. An audiogram revealed a conductive hearing loss. After exploration of the middle ear, the most common operation performed was ossiculoplasty. In the present material the most common cause of isolated malleus fractures was a sudden negative pressure in the external auditory canal created by a quick outward movement of a finger in the external ear canal. Since this fracture appears to be infrequent, it can easily be missed at otomicroscopic examination. Tympanometry and pneumatic otomicroscopy are helpful diagnostic tools.