Allograft bone vs. bioactive glass in rehabilitation of canal wall-down surgery

Canal wall-down (CWD) mastoidectomy creates a radical cavity that modifies the anatomy and physiology of the middle ear, thus preventing it from being self-cleaning and causing epidermal stagnation in the posterior cavities. Canal wall-down tympanomastoidectomy with reconstruction (CWDTwR) can obliterate such radical cavities. The main objective of this study was to compare postoperative results after CWDTwR by using either bone allografts or 45S5 bioactive glass as a filling tissue with an 18-month follow-up. This was a single-center observational trial including all patients undergoing CWDTwR. Patients were divided into two groups according to the filling material used: allograft bone (AB group) or 45S5 bioactive glass (BG group). Clinical monitoring was performed regularly, with control imaging performed at 18 months (CT scan and DW MRI). The two groups were compared with the t test for quantitative variables and the chi square test for qualitative variables (no revision surgery, audiometric results, complications, mastoid obliteration volume). Thirty-two patients underwent CWDTwR between October 2015 and 2018. The mean age was 48 years, and 71.9% (23/32) were men. A total of 46.9% (15/32) of the patients had undergone at least 3 middle-ear surgeries prior to CWDTwR. The most frequent preoperative symptom was otorrhea (100.0%, 32/32), and only 12.5% (4/32) experienced dizziness. Fifteen and 17 patients underwent surgery with bone allografts and 45S5 bioactive glass, respectively. At 18 months post-operation, 53.3% of the patients (8/15) in the AB group presented with recurrent otorrhea versus 5.9% (1/17) of patients in the BG group (p = 0.005). Seventy-eight percent (7/9) of symptomatic patients had undergone revision surgery at 18 months postoperation: 40.0% (6/15) in the AB group and 5.9% (1/17) in the BG group (p = 0.033). One patient's surgery was cancelled due to the COVID-19 pandemic, and one patient refused surgery. The effects of CWDTwR with bone allografts are disappointing in early follow-up, with significant resorption leading to a 40.0% revision surgery rate. 45S5 BG is a simple solution, with preliminary results that are superior to those of AB. However, prospective controlled studies with longer follow-up times are needed to evaluate the value of BG versus other synthetic materials (such as hydroxyapatite) in surgical management of CWDTwR.Trial registration: retrospectively registered.

Use of bonalive in obliterative mastoidectomy: anatomical results and clinical outcome

PURPOSE

To investigate safety and efficacy of mastoid obliteration in canal-wall-down tympanoplasty performed for cholesteatoma using bioactive glass (BAG). The authors routinely adopt CWD tympanoplasty in case of massive cholesteatoma or revision surgery, performing obliteration with BAG to reduce the mastoid cavity and related disadvantages. We assessed anatomical results, infection control and cholesteatoma recurrence in obliterative mastoidectomy using BAG.

METHODS

The authors evaluated 66 patients treated with obliterative mastoidectomy using BAG during the period 2010-2021. 48.5% of the cases had first diagnosis of cholesteatoma, 48.5% had cholesteatoma recidivisms, and two patients underwent obliteration to improve clinical outcome. BAG granules were always moistened with venous blood to enhance their adhesion and reduce the risk of dispersion. Anatomical results were evaluated in otomicroscopy and infection control was assessed during follow-up visits. Periodical otomicroscopy was performed to check recurrent cholesteatoma. MRI-DWI was indicated only in case of clinical suspect of cholesteatoma.

RESULTS

Authors followed 66 patients during a mean of 23 months. No post-operative wound infections occured. The mean re-epithelialization time was 45 days. At the last visit, control of infection was achieved in 97% of patients and a clinical stable anatomical cavity in all patients. No clinical suspect for recurrent cholesteatoma was found.

CONCLUSIONS

The use of bioactive glass is safe and effective as obliteration material in cholesteatoma surgery. Authors pay a particular attention to obliterate only patients without suspect of epithelial residual, to correctly calibrate the ear canal and to completely cover the granules with graft.

Implantation of two generations of Bonebridge after mastoid obliteration with bioactive glass S53P4

PURPOSE

After radical surgery for chronic cholesteatoma (CWD mastoidectomy), patients have the option to have the posterior wall of their external auditory canal surgically reconstructed with S53P4 bioactive glass. The procedure eliminates some of the restrictions related to having a postoperative cavity and extends the options for a hearing prosthesis. If classic reconstruction is not possible and a hearing aid is not used, we suggest use of a Bonebridge implant.

METHODS

This study describes, over 18 months of follow-up, 16 patients after a two-stage surgical procedure: obliteration of the mastoid cavity with bioactive glass followed by Bonebridge implantation. There were 7 patients who received the first generation implant (BCI 601) and 9 who used the second (BCI 602). Before and after implantation, pure tone audiometry, sound field thresholds, and free-field audiometry were performed. Speech reception thresholds in noise were assessed using the Polish Sentence Matrix Test. Subjective assessment of benefits was done using the APHAB (Abbreviated Profile of Hearing Aid Benefit) questionnaire.

RESULTS

During the observation period, no serious complications were found. The study demonstrated the safety and validity of the procedures and confirmed the safety of using S53P4 bioactive glass in otosurgery (antibacterial effect, nonrecurrence of cholesteatoma, and no effect on the inner ear). The audiological benefits expected from using the Bonebridge implant processor were also confirmed.

CONCLUSION

It is concluded that, after reconstructing the posterior wall of the external auditory canal with bioactive glass, two-stage implantation of a Bonebridge implant in a typical site is a safe solution for patients who have difficult anatomical conditions following their CWD mastoidectomy.

Bioactive glass in canal wall reconstruction tympanoplasty

The purpose of this Technical Note is to describe the surgical technique to transform canal wall down tympanoplasty into canal wall up tympanoplasty, that is, to rehabilitate a recess cavity by filling the mastoid and epitympanic cavities with synthetic tissue (bioactive glass) and recreating a normal-caliber external auditory canal. Mastoid cavity obliteration leads to a clinically significant improvement in health-related quality of life without increasing risk of recurrent or residual cholesteatoma, conditional upon technically impeccable surgery.

The Viability and Growth of HaCaT Cells After Exposure to Bioactive Glass S53P4-Containing Cell Culture Media

HYPOTHESIS

Bioactive glass (BG) S53P4 reduces the viability of epidermal keratinocyte-derived immortalized cell line, HaCaT in sufficient concentrations in vitro.

BACKGROUND

Although used in mastoid obliteration surgery, there is no data available on whether BG S53P4 granules have an inhibitory or excitatory effect on keratinocytes, found in normal skin and ear cholesteatoma in vivo.

METHODS

HaCaT cell cultures were incubated with a direct BG S53P4 granule contact. Microscopic evaluation of the cultures was performed and interleukin-6 (IL-6) and -8 (IL-8) concentrations were measured from the medium samples. In addition, BG granules were incubated in two cell culture media for 6 days and the pure media were used in confluent HaCaT cultures preceding cell viability assay. Finally, a scratch assay test was performed to reveal the possible BG effect on HaCaT cultures.

RESULTS

Eight to ten cell thick layers of dead HaCaT cells were noticed after a 2-day BG granule contact. With a BG concentration of 2.5%, IL-6 and IL-8 concentrations were smaller compared with the control group without BG after 2 days' incubation. Overall, HaCaT cell viability decreased when BG was incubated in keratinocyte growth medium, but did not change in Dulbecco's modified Eagle's medium. In a scratch assay test, cell regrowth in the scratch area was notable in cultures without BG.

CONCLUSIONS

BG S53P4 seems to have an inhibitory effect on HaCaT cell growth. Although further studies are needed, this observation seems advantageous for cholesteatoma treatment.

Mastoid cavity obliteration using bone pâté versus bioactive glass granules in the management of chronic otitis media (squamous disease): a prospective comparative study

OBJECTIVE

To compare the efficacy of bone pâté versus bioactive glass in mastoid obliteration.

METHOD

This randomised parallel groups study was conducted at a tertiary care centre between September 2017 and August 2019. Sixty-eight patients, 33 males and 35 females, aged 12-56 years, randomly underwent single-stage canal wall down mastoidectomy with mastoid obliteration using either bone pâté (n = 35) or bioactive glass (n = 33), and were evaluated 12 months after the operation.

RESULTS

A dry epithelised cavity (Merchant's grade 0 or 1) was achieved in 65 patients (95.59 per cent). Three patients (4.41 per cent) showed recidivism. The mean air-bone gap decreased to 16.80 ± 4.23 dB from 35.10 ± 5.21 dB pre-operatively. The mean Glasgow Benefit Inventory score was 30.02 ± 8.23. There was no significant difference between the two groups in these outcomes. However, the duration of surgery was shorter in the bioactive glass group (156.87 ± 7.83 vs 162.28 ± 8.74 minutes; p = 0.01).

CONCLUSION

The efficacy of both materials was comparable.

Implantation of the Bonebridge BCI 602 after Mastoid Obliteration with S53P4 Bioactive Glass: A Safe Method of Treating Difficult Anatomical Conditions-Preliminary Results

This study presents the preliminary results of a new otosurgical method in patients after canal wall down (CWD) surgery; it involves the implantation of the Bonebridge BCI 602 implant after obliteration of the mastoid cavity with S53P4 bioactive glass. The study involved eight adult patients who had a history of chronic otitis media with cholesteatoma in one or both ears and who had had prior radical surgery. The mean follow-up period was 12 months, with routine follow-up visits according to the schedule. The analysis had two aspects: a surgical aspect in terms of healing, development of bacterial flora, the impact on the inner ear or labyrinth, recurrence of cholesteatoma, and possible postoperative complications (firstly, after obliteration of the mastoid cavity with S53P4 bioactive glass, then after implantation). The second was an audiological aspect which assessed audiometric results and the patient’s satisfaction based on questionnaires. During the follow-up period, we did not notice any serious postoperative complications. Studies demonstrated significantly improved hearing thresholds and speech recognition in quiet and noise using the Bonebridge BCI 602. Data collected after six months of use showed improved audiological thresholds and patient satisfaction. Based on the preliminary results, we believe that the proposed two-stage surgical method using bioactive glass S53P4 is a safe and effective way of implanting the Bonebridge BCI 602 in difficult anatomical conditions. This makes it possible to treat a larger group of patients with the device.

Mastoid obliteration with S53P4 bioactive glass after canal wall down mastoidectomy: Preliminary results

BACKGROUND

Bioactive glass (S53P4), abbreviated BG, currently seems to be the best material for reconstructing the posterior wall of the auditory canal and obliterating the postoperative cavity.

PURPOSE

The aim of the study was to report preliminary results of otosurgery involving obliteration of the mastoid cavity after canal wall down mastoidectomy.

METHODS

11 adult patients who had had a history of chronic otitis media with cholesteatoma in one or both ears and previous canal wall down mastoidectomy. The duration of the follow-up was 6 months, with routine visits after 7 days, then 1, 3, and 6 months after surgery. The patient's medical history, noting other diseases potentially affecting the healing process, was analyzed. Healing, audiometric results, reduction of the volume of the cavity after surgery, and reduction of bacterial flora growth were assessed.

RESULTS

There was not worsening in the audiological evaluation. Healing period was uneventful. There was a reduction in volume of the postoperative cavity, no development of pathological flora, and no recurrence of cholesteatoma.

CONCLUSION

Obliteration of the mastoid process with S53P4 bioactive glass is a safe and effective method of treatment. Such a procedure should be considered as a treatment for patients after canal wall down surgery (CWD).

Tolerance and safety of 45S5 bioactive glass used in obliteration procedures during middle ear surgery: Preliminary results

OBJECTIVE

Otologists face many disadvantages after extensive mastoid drilling and canal wall down technique in cholesteatoma surgery. Mastoid and epitympanic cavity obliterations or reconstructions after canal wall down procedure using bioactive glass seem to be an interesting solution to overcome some of these disadvantages. Bioactive glass offers many benefits including the availability when there are no sufficient autologous materials for obliteration, its antibacterial activity in chronic infected ear and decreasing the recidivism of cholesteatoma. The objective of this study is to evaluate the tolerance and safety of 45S5 bioactive glass as a filing bone-synthetic material by clinical, audiological and radiological examinations.

METHODOLOGY

A retrospective study of 42 patients who had undergone obliteration of mastoid or/and epitympanic cavity with 45S5 bioactive glass between, November 2017 to January 2019. Data from clinical follow-ups, audiological assessment, CT-scan and MRI were analyzed.

RESULT

The patients' mean age was 49.8 years old. Microscopic examinations showed dry well-healed tympanic membranes and external auditory canals for 95.2% of the patients after 1 year. Inner ear injuries after obliteration were not observed by comparing pre and post-operative bone conduction audiometry (p value 0.457). No facial palsy was reported post-operatively. One-year postoperative radiological assessments did not reveal any silent implantation of cholesteatoma or residual disease.

CONCLUSION

Mastoid and epitympanic obliterations with 45S5 bioactive glass seem to be a tolerable and safe option in cholesteatoma surgery with favorable outcomes similar to other member of bioactive glass especially the S53P4.

Mastoid Obliteration with Synthetic Materials: A Review of the Literature

Canal wall down mastoidectomy is a surgical technique used for the eradication of middle ear disease. The remaining large mastoid bowl is associated with a number of issues; one of the main techniques that have been developed in order to avoid such problems is the obliteration of the mastoid cavity. The materials used for this reason are either biological or synthetic. The purpose of this survey is to review the published literature related to the therapeutic value of mastoid obliteration with synthetic materials. We searched Web of Science, PubMed, and MEDLINE from 2008 to 2018 using the criteria mastoid obliteration, canal wall down mastoidectomy, chronic otitis media, and cholesteatoma. The search focused on papers concerning the mastoid obliteration with synthetic material, as we focused on looking for outcomes and reported complications. Out of a total of 244 citations, 15 articles were identified, where patients underwent mastoid obliteration with synthetic materials. Most authors used bioactive glass as a filler material. Mastoid obliteration resulted in a decrease in the complications associated with the open mastoid cavity. On the basis of the available limited literature, it seems that mastoid obliteration with synthetic materials is a valuable and safe surgical technique for patients who undergo canal wall down mastoidectomy. The bioactive glass appears to be the most reliable synthetic material.

The Obliteration of Noncritical Size Bone Defects With Bone Dust or Bone Replacement Material (Bioactive Glass S53P4)

HYPOTHESIS

Bone dust (BD) harvested during operation may be suitable as an autologous obliteration material for noncritical size defects. Bioactive glass (BA) can be an alternative.

BACKGROUND

To treat noncritical size defects, BD and BA are commonly used for obliteration techniques. However, the optimal harvesting method and parameters for BD have not been examined. In this study, we analyzed the osseoregenerative potential of both materials.

METHODS

Thirteen female merino sheep (7-yr old) underwent surgery on the frontal calvaria. Three defects were inserted. The first defect was considered a reference and remained unfilled, the second defect was filled with BD from the calvaria bone, and the third defect was filled with BA S53P4. The animals were sacrificed after 3 weeks. To evaluate bone regeneration, we used digital volume tomography, bone density measurement, fluorochrome sequence labeling, and histological analysis.

RESULTS

All analyses showed quantitative and qualitative bone regeneration 3 weeks after operation. The control blank defect showed significantly less new bone growth than the BD-filled defect. Moreover, bone regeneration occurred from the surrounding bone and showed only a defect bridge in the BD-filled defect. The BA completely filled the defect and had the highest density although the same amount of new mineralized bone generated as in the reference.

CONCLUSION

BD and BA seemed to be suitable bone replacement materials for obliteration techniques because they completely filled the defects. Thus, BD harvested under standardized conditions provided a higher level of osteoreparation potential for the generation of woven bone and establishment of defect bridges.

Resorption of the calcium phosphate layer on S53P4 bioactive glass by osteoclasts

Clinically, S53P4 bioactive glass (BAG) has shown very promising results in bone infection treatment, but it is also known to degrade very slowly in vivo. To evaluate which mechanisms (cellular or dissolution) can play a role in the degradation of S53P4 BAG and S53P4 BAG putty, in vitro degradation experiments at different pH (7.4 and 4.6) were performed. Micro computed tomography showed a rapid dissolution of the synthetic binder in the putty formulation, within 12 h is simulated body fluid (pH = 7.4), leaving behind only loose granules. Therefore the degradation of the loose granules was investigated further. Significant weight loss was observed and ion chromatography showed that Ca2+, Na+ and PO43- ions were released from S54P4 BAG granules in the two fluids. It was observed that the weight loss and ion release were increased when the pH of the fluid was decreased to 4.6. Osteoclasts are known to create such a low pH when resorbing bone and therefore their capacity to degrade S53P4 surfaces were studied as well. Scanning electron microscopy and energy-dispersive X-ray spectroscopy confirmed that osteoclasts were able to create resorption pits in the calcium phosphate layer on S53P4 BAG surfaces. The silica of the BAG, located underneath the calcium phosphate, seemed to hinder further osteclastic resorption of the material. To our knowledge we were the first to observe actively resorbing osteoclasts on S53P4 bioactive glass surfaces, in vitro. Future research is needed to define the specific role osteoclasts play in the degradation of BAG in vivo.

Bioactive glass granules for mastoid and epitympanic surgical obliteration: CT and MRI appearance

PURPOSE

To evaluate the appearance of mastoid and epitympanic obliteration using S53P4 bioactive glass (BG) granules in high-resolution computed tomography (HRCT) and MRI.

MATERIALS AND METHODS

Patients undergoing mastoid and epitympanic obliteration between May 2013 and December 2015 were prospectively included in an uncontrolled clinical study. All patients underwent a temporal HRCT scan 1 year after surgery, aimed at evaluating the attenuation, homogeneity, and osseointegration of the BG granules, as well as the ventilation of the middle ear and the volume of the obliterated paratympanic spaces. If a cholesteatoma was found during surgery, additional MRI, including at least pre- and post-contrast T1-weighted, T2-weighted, and axial non-echo-planar diffusion-weighted (DW) sequences, was performed 1 year after surgery, to study the normal signal of the BG granules and the presence of residual cholesteatoma and/or other temporal bone pathologies.

RESULTS

Seventy cases were included. On 1-year HRCT, the mean attenuation of the BG granules was 888.34 ± 166.10 HU. The obliteration was found to be mostly homogeneous with partial osseointegration. The appearance of the BG granules having a low-intensity signal in T2-weighted imaging and DW MRI was always different from the appearance of cholesteatoma. A longer follow-up has shown no attenuation or signal modification of the BG granules compared with the 1-year imaging.

CONCLUSION

Radiological follow-up of patients operated on with mastoid and epitympanic obliteration using BG granules is effective using both HRCT and MRI. A cholesteatoma and/or other potential complications could easily be detected due to the specific radiological appearance of the BG granules.

KEY POINTS

• The appearance of mastoid and epitympanic obliteration by S53P4 bioactive glass (BG) granules on high-resolution computed tomography (HRCT) scans was homogeneous with an attenuation significantly higher than the attenuation of cholesteatoma and lower than mastoid bone attenuation. • The granules have a low-intensity signal on non-echo-planar diffusion-weighted sequences and on T2-weighted images and present contrast enhancement allowing the differential diagnosis with cholesteatoma and effective for the detection of other underlying temporal bone pathologies. • The volume and radiological appearance of the obliteration appear to be stable with time.

Bioglass reconstruction of posterior meatal wall after canal wall down mastoidectomy

BACKGROUND

Canal wall down (CWD) mastoidectomy has many drawbacks including chronic otorrhea, granulations, dizziness on exposure to cold or hot water and tendency of debris accumulation in the mastoid cavity demanding periodic cleaning. Many of these problems can be solved by reconstruction of the posterior meatal wall (PMW).

OBJECTIVES

To assess the results of PMW reconstruction after CWD mastoidectomy for cholesteatoma using bioactive glass (BAG) that is fabricated and built up intraoperatively.

PATIENTS AND METHODS

This study was applied on 20 patients had atticoantral chronic suppurative otitis media. All cases were subjected to CWD mastoid surgery with complete elimination of the disease and reconstruction of the PMW by BAG that was prepared and built up intraoperatively. All patients were exposed to full preoperative evaluation and full postoperative assessment of complications, appearance of the external auditory canal contour, and the hearing gain expressed by the change of the air bone gap postoperatively.

RESULTS

During a follow up of 12 to 36 months, postoperative appearance of external auditory canal contour was found smooth without hidden pouches, irregularities nor stenosis in all cases. No registered granulation, foreign body reaction, nor extrusion and/or displacement of the BAG material. No reported facial palsy or recurrent cholesteatoma. Significant hearing improvement was statistically reported (p = 0.0006).

CONCLUSION

Surgical reconstruction of the PMW using BAG that operatively fashioned immediately after CWD mastoidectomy appears to be reliable without considerable complications giving smooth appearance of the PMW and improving the hearing.

Bioactive Glasses: Where Are We and Where Are We Going?

Bioactive glasses caused a revolution in healthcare and paved the way for modern biomaterial-driven regenerative medicine. The first 45S5 glass composition, invented by Larry Hench fifty years ago, was able to bond to living bone and to stimulate osteogenesis through the release of biologically-active ions. 45S5-based glass products have been successfully implanted in millions of patients worldwide, mainly to repair bone and dental defects and, over the years, many other bioactive glass compositions have been proposed for innovative biomedical applications, such as soft tissue repair and drug delivery. The full potential of bioactive glasses seems still yet to be fulfilled, and many of today's achievements were unthinkable when research began. As a result, the research involving bioactive glasses is highly stimulating and requires a cross-disciplinary collaboration among glass chemists, bioengineers, and clinicians. The present article provides a picture of the current clinical applications of bioactive glasses, and depicts six relevant challenges deserving to be tackled in the near future. We hope that this work can be useful to both early-stage researchers, who are moving with their first steps in the world of bioactive glasses, and experienced scientists, to stimulate discussion about future research and discover new applications for glass in medicine.

Stromal Versican Regulates Tumor Growth by Promoting Angiogenesis

The proteoglycan versican is implicated in growth and metastases of several cancers. Here we investigated a potential contribution of stromal versican to tumor growth and angiogenesis. We initially determined versican expression by several cancer cell lines. Among these, MDA-MB231 and B16F10 had none to minimal expression in contrast to Lewis lung carcinoma (LLC). Notably, tumors arising from these cell lines had higher versican levels than the cell lines themselves suggesting a contribution from the host-derived tumor stroma. In LLC-derived tumors, both the tumor and stroma expressed versican at high levels. Thus, tumor stroma can make a significant contribution to tumor versican content. Versican localized preferentially to the vicinity of tumor vasculature and macrophages in the tumor. However, an ADAMTS protease-generated versican fragment uniquely localized to vascular endothelium. To specifically determine the impact of host/stroma-derived versican we therefore compared growth of tumors from B16F10 cells, which produced littleversican, in Vcan ^hdf/+ mice and wild-type littermates. Tumors in Vcan ^hdf/+ mice had reduced growth with a lower capillary density and accumulation of capillaries at the tumor periphery. These findings illustrate the variability of tumor cell line expression of versican, and demonstrate that versican is consistently contributed by the stromal tissue, where it contributes to tumor angiogenesis.

CXCR4 blockade with AMD3100 enhances Taxol chemotherapy to limit ovarian cancer cell growth

The standard of care for ovarian cancer includes initial treatment with chemotherapy. Despite initial efficacy, over 70% of patients develop recurrence; thus, there is a need to identify novel approaches that can improve therapeutic outcomes. We evaluated AMD3100 (Plerixafor), an FDA-approved CXCR4 inhibitor, as a potential adjunctive therapy for low-dose Taxol (Paclitaxel) by assessing the impact on in-vitro ovarian cancer cell proliferation. Proliferation was a measure for both human TOV-112D and murine ID8 ovarian cancer cells incubated with AMD3100 and Taxol, either individually or in combination. Impact of treatment was first determined for the simultaneous administration of AMD3100 and Taxol. We next assessed a sequential application of AMD3100 pretreatment, followed by AMD3100, Taxol, or a combination to test for sensitization to Taxol. In addition, we measured the impact of AMD3100 and Taxol, individually and in combination, on colony formation, an in-vitro model assay of tumor growth. Expression data, as measured by flow cytometry, show that both ID8 and TOV-112D cells are positive for CXCR4, CXCR7, and CXCL12. Combination treatment with AMD3100 (≤10 μmol/l) sensitized both ID8 and TOV-112D cells to low concentrations of Taxol (≤5 nmol/l), limiting cell proliferation and colony formation in vitro. Pretreatment with AMD3100 significantly increased the sensitivity of human ovarian cancer to low-dose Taxol or the combination of AMD3100 and Taxol, although this effect was not evident in murine cells. Importantly, for both human and murine cells, incubation with a combination of AMD3100 and Taxol had the largest impact on limiting cell proliferation. AMD3100 in combination with low-dose Taxol offers improved efficacy and the potential of reduced toxicity for the treatment of ovarian cancer.

Osteotomy Site Grafting in Bilateral Sagittal Split Surgery With Bioactive Glass S53P4 for Skeletal Stability

In orthognathic surgery, the aim of the treatment is to achieve a good occlusion and a satisfying aesthetic outcome. In large mandibular advancements insufficient healing at the mandibular inferior border may lead to loss of support for the overlaying tissue at the osteotomy site. Augmentation can be performed to improve stability, bone regeneration, and the aesthetic outcome. The purpose of this prospective clinical study was to evaluate the use of a novel material for this indication; granules of the antibacterial, osteoconductive, and slowly resorbing bioactive glass S53P4 as filling material in large mandibular advancement in bilateral sagittal split osteotomies. The authors treated 25 patients who underwent bilateral sagittal split osteotomies due to class II dentoskeletal deformities. The mandibular osteotomy site defects (8-15 mm) were augmented with bioactive glass S53P4. The average clinical follow-up was 33 months and the average radiological follow-up with cone beam computerized tomography was 24 months. The clinical and radiological results were good with regard to healing, bone regeneration, and stability of the osteotomy sites. The recontouring of the inferior mandibular border provided a good soft tissue support followed by an excellent aesthetic outcome in 96% of the osteotomy sites. The occlusion was stable in 88% of the patients. The authors' results show that bioactive glass S53P4 is a safe grafting material for osteotomy site defects in significant mandibular advancements with reliable bone regeneration, providing long-term stability at the osteotomy site and at the inferior mandibular border.

Bioactive glass obliteration of the mastoid significantly improves surgical outcome in non-cholesteatomatous chronic otitis media patients

This retrospective follow-up study evaluates the efficacy and safety of bioactive glass (BAG) S53P4 when applied as filler material in mastoid obliteration surgery performed on non-cholesteatomatous chronic otitis media (NC-COM) patients with chronically discharging ears despite conservative therapy. 94 Patients (96 ears) were included. Patients underwent either intact canal wall (ICW) or canal wall down (CWD) mastoid surgery between 2005 and 2015. The intervention group comprised 23 patients (23 ears) who were treated with additional mastoid obliteration using BAG S53P4; the remaining 71 patients (73 ears) were considered controls. All patients underwent preoperative CT scanning of the mastoid. Primary functional outcome, as defined by control of suppuration, was assessed using Merchant's scale. Hearing results as measured by air-bone gap and the incidence of adverse events were assessed as secondary outcomes. Thirty-two ears (44%) in the control group (n = 73) achieved complete control of infection at the most recent postoperative clinic visit vs 17 (74%) in the S53P4 obliteration group (n = 23). Comparing these outcomes yielded an odds ratio (OR) of 3.6 (p = 0.012, 95% CI 1.3-10.3). Complete failure to manage infection significantly differed (p = 0.048) between the control group (11 ears; 15%) and the S53P4 obliteration group (0 ears). No adverse events were observed in either group. Pre- and postoperative ABG results did not differ significantly between groups. Obliteration of the mastoid cavity using BAG S53P4 along with mastoidectomy in patients with chronically discharging NC-COM significantly improves the achievement of a dry and safe ear as compared to mastoidectomy alone. Importantly, no adverse events were observed with S53P4 BAG obliteration.

Regeneration of Cystic Bone Cavities and Bone Defects With Bioactive Glass S53P4 in the Upper and Lower Jaws

Cysts and tumors are common lesions in the jaws. To be able to retain a good volume of the alveolar ridge during healing as well as strengthening the angle and body of the mandible and provide an instant improved support for adjacent teeth, reliable long-term bone regeneration is needed. The purpose of this prospective study was to promote bone regeneration by filling bony defects in the upper or lower jaw with granules of the bioactive glass S53P4 (BAG), which have osteostimulative and antimicrobial properties.The authors treated 20 patients (21 defects) surgically; benign tumors, cysts, or infection related to impacted teeth in the maxilla or mandible. The tumor or cyst was removed or enucleated and thorough cleaning of the infected area was performed. The bone cavity was filled with granules of the BAG S53P4 despite signs of chronic infection in the area at the time of surgery. The patients were followed up for an average of 34 months clinically and with cone beam computerized tomography for 28 months. In 20 defects the final outcome was successful. Despite infection at the time of surgery in 65% of the patients, no material associated infection was seen during the follow-up. The BAG S53P4 granules were radiologically remodeled into bone after 2 years follow-up. The use of granules of the BAG S53P4 in the treatment of large bone defects provides infection-free reliable bone regeneration despite chronic infection at the time of surgery, which improves the prognosis of adjacent teeth.

Anatomical, functional and quality-of-life results for mastoid and epitympanic obliteration with bioactive glass s53p4: a prospective clinical study

OBJECTIVE

To analyse the anatomical, functional and quality-of-life results when using bioactive glass in mastoid and epitympanic obliteration.

DESIGN

Prospective clinical study.

SETTING

Tertiary referral centre.

PARTICIPANTS

Forty-one cases (39 patients) operated between May 2013 and January 2015.

MAIN OUTCOME MEASURES

Anatomical results were evaluated by otomicroscopy 1 year after surgery and using imaging to detect residual disease. Functional results were studied by postoperative hearing gain. Quality of life was assessed with the Glasgow Benefit Inventory questionnaire and the success of surgery by a surgery-specific questionnaire.

RESULTS

At 1 year, all patients presented a well-healed external auditory canal, with an intact tympanic membrane. In cases with cholesteatoma (n = 23), no recurrent retraction pockets or residual disease were observed on imaging studies. The overall air-bone gap closure was 7.7 ± 1.84 dB (mean ± se of the mean, P < 0.001, paired t-test). No significant differences were found on hearing results when comparing primary versus revision surgery, canal-wall-up versus canal-wall-down obliterations, type of tympanoplasty and presence of cholesteatoma (multifactor anova). The Glasgow Benefit Inventory improved with an average score of 28 and the success of surgery questionnaire showed a significant improvement in ear discharge and a moderate improvement in hearing and equilibrium.

CONCLUSIONS

The use of bioactive glass for mastoid and epitympanic obliteration in canal-wall-down or canal-wall-up tympanoplasties is an effective procedure in both primary and revision surgery. The anatomical and functional results appear to be well correlated with patient experience and to the improvement in quality of life.

Reconstruction of Vertebral Bone Defects using an Expandable Replacement Device and Bioactive Glass S53P4 in the Treatment of Vertebral Osteomyelitis: Three Patients and Three Pathogens

BACKGROUND AND AIMS

Bioactive glass S53P4 is an antibacterial bone substitute with bone-bonding and osteostimulative properties. The bone substitute has been successfully used clinically in spine; trauma; orthopedic; ear, nose, and throat; and cranio-maxillofacial surgeries. Bioactive glass S53P4 significantly reduces the amount of bacteria in vitro and possesses the capacity to kill both planktonic bacteria and bacteria in biofilm. Three patients with severe spondylodiscitis caused by Mycobacterium tuberculosis, Candida tropicalis, or Staphylococcus aureus were operatively treated due to failed conservative treatment. The vertebral defects were reconstructed using bioactive glass S53P4 and an expandable replacement device.

MATERIAL AND METHODS

Decompression and a posterolateral spondylodesis, using transpedicular fixation, were performed posteriorly in combination with an anterior decompression and reconstruction using an expandable vertebral body replacement device. For patients 1 and 2, the expander was covered with bioactive glass S53P4 only, and for patient 3, the glass was mixed with autograft bone.

RESULTS

The patients healed well with complete neurological recovery. Fusion was observed for all patients. The total follow-up was 4 years for patient 1, 1 year and 8 months for patient 2, and 2 years and 2 months for patient 3. No relapses or complications were observed.

CONCLUSION

The antibacterial properties of bioactive glass S53P4 also make it a suitable bone substitute in the treatment of severe spondylodiscitis.

Mechanical behaviour of Bioactive Glass granules and morselized cancellous bone allograft in load bearing defects

Bioactive Glass (BAG) granules are osteoconductive and possess unique antibacterial properties for a synthetic biomaterial. To assess the applicability of BAG granules in load-bearing defects, the aim was to compare mechanical behaviour of graft layers consisting of BAG granules and morselized cancellous bone allograft in different volume mixtures under clinically relevant conditions. The graft layers were mechanically tested, using two mechanical testing modalities with simulated physiological loading conditions: highly controllable confined compression tests (CCT) and more clinically realistic in situ compression tests (ISCT) in cadaveric porcine bone defects. Graft layer impaction strain, residual strain, aggregate modulus, and creep strain were determined in CCT. Graft layer porosity was determined using micro computed tomography. The ISCT was used to determine graft layer subsidence in bone environment. ANOVA showed significant differences (p<0.001) between different graft layer compositions. True strains absolutely decreased for increasing BAG content: impaction strain -0.92 (allograft) to -0.39 (BAG), residual strain -0.12 to -0.01, and creep strain -0.09 to 0.00 respectively. Aggregate modulus increased with increasing BAG content from 116 to 653MPa. Porosity ranged from 66% (pure allograft) to 15% (pure BAG). Subsidence was highest for allograft, and remarkably low for a 1:1 BAG-allograft volume mixture. Both BAG granules and allograft morsels as stand-alone materials exhibit suboptimal mechanical behaviour for load-bearing purpose. BAG granules are difficult to handle and less porous, whereas allograft subsides and creeps. A 1:1 volume mixture of BAG and allograft is therefore proposed as the best graft material in load-bearing defects.

BAG-S53P4 as an additive to bone allografts: A laboratory study using an uniaxial compression test

We want to address the clinical issue of too sparse supply of allograft in total hip replacement and ambitions of controlling the grain size distribution. Bioglass BAG-S53P4 was evaluated as a bone graft additive to chemically treated allografts with controlled grain size distribution. Allografts were chemically cleaned (CG) and mixed with BAG-S53P4 additive (BG) for comparison. All samples were compacted with a dropped weight apparatus and then underwent a uniaxial compression test. The yield limit was determined by a uniaxial compression test and density was recorded while flowability was calculated. There was no difference between the yield stress limit of BG and CG after compaction (p=0.432). Adding BAG-S53P4 reduced flowability and could indicate better interlocking mechanism between particles. Adding BAG-S53P4 seems to have no impact on the yield stress limit. The extended allografts withstand the compaction equally good which makes it a valid bone substitute in total hip replacement. An in vivo loaded study is needed before clinical use can be recommended.

Cutaneous and Labyrinthine Tolerance of Bioactive Glass S53P4 in Mastoid and Epitympanic Obliteration Surgery: Prospective Clinical Study

Objective. To evaluate the cutaneous and the inner ear tolerance of bioactive glass S53P4 when used in the mastoid and epitympanic obliteration for chronic otitis surgery. Material and Methods. Forty-one cases have been included in this prospective study. Cutaneous tolerance was clinically evaluated 1 week, 1 month, and 3 months after surgery with a physical examination of the retroauricular and external auditory canal (EAC) skin and the presence of otalgia; the inner ear tolerance was assessed by bone-conduction hearing threshold 1 day after surgery and by the presence of vertigo or imbalance. Results. All surgeries but 1 were uneventful: all patients maintained the preoperative bone-conduction hearing threshold except for one case in which the round window membrane was opened during the dissection of the cholesteatoma in the hypotympanum and this led to a dead ear. No dizziness or vertigo was reported. Three months after surgery, healing was achieved in all cases with a healthy painless skin. No cases of revision surgery for removal of the granules occurred in this study. Conclusion. The bioactive glass S53P4 is a well-tolerated biomaterial for primary or revision chronic otitis surgery, as shown by the local skin reaction which lasted less than 3 months and by the absence of labyrinthine complications.

Clinical Applications of S53P4 Bioactive Glass in Bone Healing and Osteomyelitic Treatment: A Literature Review

Nowadays, S53P4 bioactive glass is indicated as a bone graft substitute in various clinical applications. This review provides an overview of the current published clinical results on indications such as craniofacial procedures, grafting of benign bone tumour defects, instrumental spondylodesis, and the treatment of osteomyelitis. Given the reported results that are based on examinations, such as clinical examinations by the surgeons, radiographs, CT, and MRI images, S53P4 bioactive glass may be beneficial in the various reported applications. Especially in craniofacial reconstructions like mastoid obliteration and orbital floor reconstructions, in grafting bone tumour defects, and in the treatment of osteomyelitis very promising results are obtained. Randomized clinical trials need to be performed in order to determine whether bioactive glass would be able to replace the current golden standard of autologous bone usage or with the use of antibiotic containing PMMA beads (in the case of osteomyelitis).

Effects of S53P4 bioactive glass on osteoblastic cell and biomaterial surface interaction

To study the effect of bioactive glass bone substitute granules (S53P4) and hypoxic atmospheric conditions on human osteoblastic cell adhesion on different biomaterials. Cellular adhesion and cytoskeletal organization were studied on titanium, polytetrafluoroethylene, polydimethylsiloxane and S53P4 plates in the presence or absence of S53P4 granules. Cells used were human osteoblast-like SaOS-2 cells. The experiments were done either in normal atmospheric conditions or in hypoxia which simulates conditions prevailing in chronically infected bone or bone cavities. Vinculin-containing focal adhesions, organization of actin cytoskeleton and nuclear staining of cells on biomaterial surfaces were studied at 4.5 h, 2 and 4 days. In normoxic conditions S53P4 granules alkalinized the cell culture medium but cellular adhesion and cytoskeletal organization were usually not affected by their presence. Hypoxic conditions associated with lower pH and impaired cellular adhesion, vinculin-containing focal adhesion formation and rearrangement of the actin filaments to actin cytoskeleton. On most materials studied in hypoxic conditions, however, S53P4 granules prevented this impairment of cellular adhesion and cytoskeletal reorganization. The S53P4 granules promote the adhesion of SaOS-2 cells to various biomaterial surfaces especially in hypoxic conditions, in which S53P4 granules increase pH. The presence of S53P4 granules may protect biomaterial surface from bacterial colonization and promote osteointegration of implants used together with S53P4 granules for fixation and weight bearing.

Reprint of: Review of bioactive glass: From Hench to hybrids

Bioactive glasses are reported to be able to stimulate more bone regeneration than other bioactive ceramics but they lag behind other bioactive ceramics in terms of commercial success. Bioactive glass has not yet reached its potential but research activity is growing. This paper reviews the current state of the art, starting with current products and moving onto recent developments. Larry Hench's 45S5 Bioglass® was the first artificial material that was found to form a chemical bond with bone, launching the field of bioactive ceramics. In vivo studies have shown that bioactive glasses bond with bone more rapidly than other bioceramics, and in vitro studies indicate that their osteogenic properties are due to their dissolution products stimulating osteoprogenitor cells at the genetic level. However, calcium phosphates such as tricalcium phosphate and synthetic hydroxyapatite are more widely used in the clinic. Some of the reasons are commercial, but others are due to the scientific limitations of the original Bioglass 45S5. An example is that it is difficult to produce porous bioactive glass templates (scaffolds) for bone regeneration from Bioglass 45S5 because it crystallizes during sintering. Recently, this has been overcome by understanding how the glass composition can be tailored to prevent crystallization. The sintering problems can also be avoided by synthesizing sol-gel glass, where the silica network is assembled at room temperature. Process developments in foaming, solid freeform fabrication and nanofibre spinning have now allowed the production of porous bioactive glass scaffolds from both melt- and sol-gel-derived glasses. An ideal scaffold for bone regeneration would share load with bone. Bioceramics cannot do this when the bone defect is subjected to cyclic loads, as they are brittle. To overcome this, bioactive glass polymer hybrids are being synthesized that have the potential to be tough, with congruent degradation of the bioactive inorganic and the polymer components. Key to this is creating nanoscale interpenetrating networks, the organic and inorganic components of which have covalent coupling between them, which involves careful control of the chemistry of the sol-gel process. Bioactive nanoparticles can also now be synthesized and their fate tracked as they are internalized in cells. This paper reviews the main developments in the field of bioactive glass and its variants, covering the importance of control of hierarchical structure, synthesis, processing and cellular response in the quest for new regenerative synthetic bone grafts. The paper takes the reader from Hench's Bioglass 45S5 to new hybrid materials that have tailorable mechanical properties and degradation rates.

Effect of S53P4 bone substitute on staphylococcal adhesion and biofilm formation on other implant materials in normal and hypoxic conditions

To study the effect of bioactive glass bone substitute granules (S53P4) on bacterial adhesion and biofilm formation on other simultaneously used implant materials and the role of the hypoxic conditions to the adhesion. Bacterial and biofilm formation were studied on materials used both in middle ear prostheses and in fracture fixtures (titanium, polytetrafluoroethylene, polydimethylsiloxane and bioactive glass plates) in the presence or absence of S53P4 granules. The experiments were done either in normal atmosphere or in hypoxia simulating atmospheric conditions of middle ear, mastoid cavity and sinuses. We used two collection strains of Staphylococcus aureus and Staphylococcus epidermidis. In the presence of bioglass and hypoxic conditions the adhesion of the planktonic bacterial cells was decreased for most of the materials. The biofilm formation was decreased for S. epidermidis on titanium and polydimethylsiloxane in both atmospheric conditions and on bioglass plates in normoxia. For S. aureus the biofilm formation was decreased on bioglass plates and polytetrafluoroethylene in normoxia. Hypoxia produces a decrease in the biofilm formation only for S. aureus on polytetrafluoroethylene and for S. epidermidis on bioglass plates. However, in none of the cases bioactive glass increased the bacterial or biofilm adhesion. The presence of bioglass in normoxic and hypoxic conditions prevents the bacterial and biofilm adhesion on surfaces of several typical prosthesis materials in vitro. This may lead to diminishing postoperative infections, however, further in vivo studies are needed.

Bioactive-glass in Oral and Maxillofacial Surgery

The use of synthetic materials to repair craniofacial defects is increasing today and will increase further in the future. Because of the complexity of the anatomy in the head and neck region, reconstruction and augmentation of this area pose a challenge to the surgeon. This review discusses key facts and applications of traditional reconstruction bone substitutes, also offering comparative information. It then describes the properties and clinical applications of bioactive-glass (B-G) and its variants in oral and maxillofacial surgery, and provides clinical findings. The discussion of each compound includes a description of its composition and structure, the advantages and shortcomings of the material, and its current uses in the field of osteoplastic and reconstructive surgery. With a better understanding of the available alloplastic implants, the surgeon can make a more informed decision as to which implant would be most suitable in a particular patient.

The use of anatomically drop-shaped bioactive glass S53P4 implants in the reconstruction of orbital floor fractures--A prospective long-term follow-up study

An isolated fracture of the orbital floor needs reconstruction if there is a clear herniation of adipose tissue or of the rectus inferior muscle into the maxillary sinus. A prospective study was carried out treating 20 patients with an isolated blow-out fracture of the orbital floor or with a combined zygomatico-orbito-maxillary complex fracture, using a newly designed anatomically drop-shaped implants made of bioactive glass (BAG) S53P4. Computed tomography (CT) was performed immediately postoperatively to confirm the correct position of the plate. The patients were followed up for an average of 32 months clinically and radiologically with magnetic resonance imaging (MRI) for an average of 31 months. None of the patients had any signs of complications related to the implant and the clinical outcome was very good. None of the patients had persisting diplopia. The level of the pupillas was normal in 15 of 20 patients. Minor hypo-ophthalmos ranging from 0.5 to 1.0 mm was observed in three patients, and moderate hypo-ophthalmos of 2.0 mm was seen in one patient. Hyperophthalmos of 1.0 mm was seen in one patient. Minor enophthalmos on the operated side ranging from 0.5 to 1.0 mm was seen in eight patients. Mild to moderate paraesthesia of the infraorbital nerve was observed in six patients. The immediate postoperative CT and the long term follow-up MRI revealed that the drop-shaped BAG implants retained their correct position in the orbital floor and did not show any evidence of losing their original shape or material resorption. No adverse tissue reaction was associated with the material. Due to the anatomical drop shape, the implants could successfully maintain the orbital volume and compensate for the retrobulbar adipose tissue atrophy.

Health-related quality of life measurement after cholesteatoma surgery: comparison of three different surgical techniques

The objective of this study was to compare health-related quality of life (HRQOL) after sequential cholesteatoma surgery including exclusively transcanal technique (ETC), combined transcanal transmastoidal technique (TCM) and canal wall down surgery with obliteration (CWD). It was a clinical case study conducted in a tertiary referral center. 97 patients at least 12 months after cholesteatoma surgery were included. Interventions included sequential cholesteatoma surgery with ETC, TCM or CWD; ossiculoplasty with partial and total ossicular replacement prostheses. HRQOL assessed by Chronic Otitis Media Outcome Test 15 including an overall score and three subscores ('ear symptoms', 'hearing function' and 'mental health') as well as a general evaluation of HRQOL and the frequency of physician consultations, audiometric outcome related to HRQOL were the main outcome measures. Patients, who had undergone sequential cholesteatoma surgery, showed moderate restrictions in HRQOL postoperatively. Stratified for the three surgical techniques, patients receiving ETC tended to report lower restrictions in HRQOL. The ETC group offered a significantly lower value in the subscore 'ear symptoms'. The 'hearing function' was attributed to be the most restriction criteria for all techniques. The overall score and all subscores correlated moderately with the postoperative air conduction threshold. The strongest correlation coefficient was achieved for the subscore 'hearing function' (r(s) = 0.49, p < 0.001). Sequential cholesteatoma surgery offers acceptable moderate restrictions in HRQOL postoperatively. Patients receiving canal wall down surgery with obliteration showed equivalent limitations in HRQOL compared to closed techniques (ETC, TCM). The postoperative air conduction threshold was shown not to be a sufficient indicator for HRQOL. Therefore, disease-specific validated and reliable measuring instruments for HRQOL should be transferred from clinical research to clinical practice to provide an individualized postoperative assessment after cholesteatoma surgery.

A comparative study of the use of bioactive glass S53P4 and antibiotic-loaded calcium-based bone substitutes in the treatment of chronic osteomyelitis: a retrospective comparative study

The treatment of chronic osteomyelitis often includes surgical debridement and filling the resultant void with antibiotic-loaded polymethylmethacrylate cement, bone grafts or bone substitutes. Recently, the use of bioactive glass to treat bone defects in infections has been reported in a limited series of patients. However, no direct comparison between this biomaterial and antibiotic-loaded bone substitute has been performed. In this retrospective study, we compared the safety and efficacy of surgical debridement and local application of the bioactive glass S53P4 in a series of 27 patients affected by chronic osteomyelitis of the long bones (Group A) with two other series, treated respectively with an antibiotic-loaded hydroxyapatite and calcium sulphate compound (Group B; n = 27) or a mixture of tricalcium phosphate and an antibiotic-loaded demineralised bone matrix (Group C; n = 22). Systemic antibiotics were also used in all groups. After comparable periods of follow-up, the control of infection was similar in the three groups. In particular, 25 out of 27 (92.6%) patients of Group A, 24 out of 27 (88.9%) in Group B and 19 out of 22 (86.3%) in Group C showed no infection recurrence at means of 21.8 (12 to 36), 22.1 (12 to 36) and 21.5 (12 to 36) months follow-up, respectively, while Group A showed a reduced wound complication rate. Our results show that patients treated with a bioactive glass without local antibiotics achieved similar eradication of infection and less drainage than those treated with two different antibiotic-loaded calcium-based bone substitutes.

Bioactive glass BAG-S53P4 for the adjunctive treatment of chronic osteomyelitis of the long bones: an in vitro and prospective clinical study

BACKGROUND

This study aimed to explore the in vitro antibacterial activity of the bioglass BAG S53P4 against multi-resistant microorganisms commonly involved in osteomyelitis and to evaluate its use in surgical adjunctive treatment of osteomyelitis.

METHODS

In vitro antibacterial activity of BAG-S53P4 against methicillin resistant Staphylococcus aureus and Staphylococcus epidermidis, Pseudomonas aeruginosa and Acinetobacter baumannii isolates was evaluated by means of time kill curves, with colony counts performed after 24, 48 and 72 hours of incubation. In vivo evaluation was performed by prospectively studying a cohort of 27 patients with a clinically and radiologically diagnosed osteomyelitis of the long bones in an observational study. Endpoints were the absence of infection recurrence/persistence at follow-up, no need for further surgery whenever during follow-up and absence of local or systemic side effects connected with the BAG use.

RESULTS

In vitro tests regarding the antibacterial activity of BAG S53P4 showed a marked bactericidal activity after 24 hrs against all the tested species. This activity continued in the subsequent 24 hrs and no growth was observed for all strains after 72 hrs. Results of the clinical study evidenced no signs of infection in 24 patients (88.9%) at the follow-up, while 2 subjects showed infection recurrence at 6 months from index operation and one more needed further surgical procedures. BAG-S53P4 was generally well tolerated.

CONCLUSIONS

The in vitro and in vivo findings reinforce previous observations on the efficacy of BAG-S53P4 for the treatment of chronic osteomyelitis of the long bones, also in the presence of multi-resistant strains and in immunocompromised hosts, without relevant side effects and without the need for locally adding antibiotics.

TRIAL REGISTRATION

Deutschen Register Klinischer Studien (DRKS) unique identifier: DRKS00005332.

Intraoperative findings of revision canal wall-down tympanomastoid surgery

CONCLUSION

Chronically discharging mastoid cavities had well-defined technical faults from previous surgery. Identifying and eliminating these errors during revision canal wall-down (CWD) tympanomastoidectomy converted troublesome mastoid cavities into safe ears in 84% of cases.

OBJECTIVE

To assess intraoperative findings of revision CWD tympanomastoidectomy to determine the most common causes of failure of previous surgery. The short-term results of revision surgery after a 12-month follow-up period were analyzed.

METHODS

The study group consisted of 50 consecutive patients, 27 males and 23 females, aged 7-63 years (mean 34 ± 17 years) undergoing revision CWD tympanomastoidectomy due to persistently discharging mastoid cavities. The outcome of revision surgery was measured semi-quantitatively using a grading system.

RESULTS

The most common causes for failure of previous surgery were persistent mastoid cells in the tegmental, sinodural angle, and the retrolabyrinthine, retrofacial, and mastoid tip regions (100%); the bony overhangs at the edges of the mastoid cavity and the high facial ridge (98%); inadequately narrow meatus (84%); recurrent or residual cholesteatoma (46%); and remaining malleus head (40%). Revision surgery included elimination of all encountered limitations followed by mastoid cavity obliteration in about two-thirds of cases. Hearing restoration was done in only 34% of ears. In the remaining cases, intact ossicular chain (6%), existing sufficient previous reconstruction (22%) or impossible situation for reconstruction (38%) was found.

Use of granules of biphasic ceramic in rehabilitation of canal wall down mastoidectomy

The objective of this study is to evaluate the anatomical and functional results of rehabilitation of canal wall down (CWD) mastoidectomy using granules of biphasic ceramic. This is a study design retrospective in a tertiary referral centre Fifty-seven patients (59 ears) operated on between 2006 and 2010 of mastoid obliteration with granules of biphasic ceramic (TricOs, Maurepas, France) have been included (55 revisions and 4 first surgeries). Forty-six patients presented already a CWD mastoidectomy. The mean pre-operative bone conduction (BC) was 29 ± 3.4 dB (mean ± SEM) and mean air conduction (AC) was 57 ± 3.2 dB. Cholesteatoma was found in 33 cases. All but seven cases had post-operative otoscopy examination at 1, 3, 6 months, and 1 year postoperative with a CT scan and pure tone audiometry. Mean follow-up was 14 ± 1.8 months (3-35). At one-year follow-up (n = 52), 47 cases (90 %) presented well-healed external auditory canal. Five cases (10 %) of uncovered granules without sign of infection of external auditory canal skin were observed. Mean post-operative threshold was 25 ± 1.8 and 46 ± 1.9 dB for BC and AC , respectively (n = 47). CT scan (n = 42) showed no opacity suggesting residual disease within or behind obliteration. Mastoid obliteration with granules of biphasic ceramic is a safe and effective procedure that allows restoration of a near normal external auditory canal.

Review of bioactive glass: from Hench to hybrids

Bioactive glasses are reported to be able to stimulate more bone regeneration than other bioactive ceramics but they lag behind other bioactive ceramics in terms of commercial success. Bioactive glass has not yet reached its potential but research activity is growing. This paper reviews the current state of the art, starting with current products and moving onto recent developments. Larry Hench's 45S5 Bioglass® was the first artificial material that was found to form a chemical bond with bone, launching the field of bioactive ceramics. In vivo studies have shown that bioactive glasses bond with bone more rapidly than other bioceramics, and in vitro studies indicate that their osteogenic properties are due to their dissolution products stimulating osteoprogenitor cells at the genetic level. However, calcium phosphates such as tricalcium phosphate and synthetic hydroxyapatite are more widely used in the clinic. Some of the reasons are commercial, but others are due to the scientific limitations of the original Bioglass 45S5. An example is that it is difficult to produce porous bioactive glass templates (scaffolds) for bone regeneration from Bioglass 45S5 because it crystallizes during sintering. Recently, this has been overcome by understanding how the glass composition can be tailored to prevent crystallization. The sintering problems can also be avoided by synthesizing sol-gel glass, where the silica network is assembled at room temperature. Process developments in foaming, solid freeform fabrication and nanofibre spinning have now allowed the production of porous bioactive glass scaffolds from both melt- and sol-gel-derived glasses. An ideal scaffold for bone regeneration would share load with bone. Bioceramics cannot do this when the bone defect is subjected to cyclic loads, as they are brittle. To overcome this, bioactive glass polymer hybrids are being synthesized that have the potential to be tough, with congruent degradation of the bioactive inorganic and the polymer components. Key to this is creating nanoscale interpenetrating networks, the organic and inorganic components of which have covalent coupling between them, which involves careful control of the chemistry of the sol-gel process. Bioactive nanoparticles can also now be synthesized and their fate tracked as they are internalized in cells. This paper reviews the main developments in the field of bioactive glass and its variants, covering the importance of control of hierarchical structure, synthesis, processing and cellular response in the quest for new regenerative synthetic bone grafts. The paper takes the reader from Hench's Bioglass 45S5 to new hybrid materials that have tailorable mechanical properties and degradation rates.

Bioactive Glass S53P4 in Mastoid Obliteration Surgery for Chronic Otitis Media and Cerebrospinal Fluid Leakage

Objectives:

We evaluated the results of cases of chronic otitis media treated with mastoid obliteration surgery using bioactive glass S53P4.

Methods:

Twenty-five patients with chronic otitis media and 1 patient with cerebrospinal fluid leakage without chronic infection were treated with bioactive glass S53P4. Twenty patients had had previous surgery because of chronic otitis media with or without cholesteatoma. A mastoid obliteration was performed with bioactive glass S53P4 granules and a musculoperiosteal flap with or without bone paté. In 2 patients with a bony dehiscence at the middle cranial fossa, a bioactive glass plate was used to support the protruding dura. In addition, in 3 patients, occlusion of a dural fistula was needed. The median follow-up period was 34.5 months (range, 1 to 182 months).

Results:

Excluding the 2 patients with only 1 month of follow-up at our department, 96% of the patients had a dry, safe ear or only intermittent otorrhea. In 92% of the patients, the objective of achieving a smaller or nonexistent cavity was achieved.

Conclusions:

Bioactive glass S53P4 is a noteworthy material in mastoid obliteration surgery.

Mastoidectomy cavity obliteration with bioactive glass: a pilot study

OBJECTIVE

To show that mastoid cavities with continuous infections and cleaning problems can be obliterated with bioactive glass (BG) and to present results of a pilot study for 16 operations on adults.

STUDY DESIGN

Case series with planned data collection.

SETTING

Päijät-Häme Central Hospital, Finland-a single ear, nose, and throat (ENT) hospital department serving a population of 216,000.

SUBJECTS AND METHODS

Fourteen patients had a large open radical cavity with recurrent infections. Two ears had discharge and pain after simple mastoidectomy. A re-mastoidectomy included support of the cavity skin and obliteration with BG. The mean follow-up time was 2.2 years.

RESULTS

All ears became dry. One reoperation was needed as the fascia support to the ear canal (EC) skin was too weak, and part of the BG leaked into the EC. The ear stayed dry, and the missing BG was replaced in a reoperation. A slightly short musculoperiosteal flap supported the EC skin in 1 ear. A minor amount of BG leaked into the EC. The ear stayed dry. The aim was an ample ear canal. One ear was overfilled and required meatoplasty. Simple mastoid cavities were isolated from the middle ear and become asymptomatic.

CONCLUSIONS

In this pilot study, BG works safely and with success as an obliteration material in problematic open radical cavities. Bioactive glass seems to tolerate chronic infection in the mastoid and prevent postoperative infections.