Hydroxylapatite ossicular replacement prostheses: a four-year experience

The Effect of Anteriorly Located Sigmoid Sinus on Postoperative Hearing Gains: A Case-Control Study

There are many studies on the effects of temporal bone anatomical variations on a mastoid pneumatization. Considering the effects of the anatomic variations on mastoid pneumatization, it is considered that many anatomic variations may affect graft success rates and postoperative hearing threshold gains. We aimed to evaluate the effects of various anatomic variations on postoperative hearing gains among patients undergoing tympanoplasty. This retrospective cohort study conducted in a tertiary-care university hospital. This study enrolled 57 patients who underwent primary type 1 tympanoplasty operation using the temporal muscle fascia. The patients were divided into two groups as those with an anteriorly located sigmoid sinus (group 1), and no anatomic variation (group 2). Airway gain values at the frequency range of 250 Hz-8000 Hz and pure tone average (PTA) value were calculated preoperatively and at postoperative sixth month. The gains attained by the patient groups with anatomic variations were compared with group 2. There were significant differences between Group 1 and Group 2 in terms of the airway frequencies of 250, 500, 2000, 4000 Hz, and PTA value. We detected a lesser postoperative hearing gain in patients with an anteriorly located SS. We believe that anatomic variations that may affect middle ear and mastoid cavity may also affect postoperative hearing gain.

Stapes stabilizing cartilage graft

PURPOSE

This study aimed to evaluate hearing results in patients with type 3 tympanoplasty using autologous cartilage grafts.

METHODS

The study included patients treated with "stapes stabilizing cartilage graft" (SSCG) and Plastipore partial ossicular replacement prosthesis (PPORP) for hearing reconstruction. Hearing results and complications were assessed and postoperative audiological tests were performed at least 6 months after surgery.

RESULTS

There were 18 patients (5 men, 13 women) in the SSCG group and 12 patients (5 men, 7 women) in the PPORP group. The air conduction threshold changed by 22.4 ± 7.5 dB in the SSCG group, and by 13.2 ± 12.9 dB in the PPORP group (p = 0.022), after hearing reconstruction. The air-bone gap (ABG) changed by 20.1 ± 8.3 dB in the SSCG group and by 16.3 ± 12.3 dB in the PPORP group. Although the change in ABG was greater in the SSCG group than in the PPORP group, the difference was not statistically significant (p > 0.05). No complications were recorded in the SSCG group, whereas two patients experienced a severe vertigo attack after surgery in the PPORP group, which lasted for approximately 2 weeks with conservative management. Extrusion was not encountered in the PPORP group, while extrusion of the titanium partial ossicular replacement prosthesis occurred in one patient in the SSCG group who underwent revision surgery.

CONCLUSIONS

Better hearing outcomes were obtained with SSCG than with PPORP. SSCG can be used as an alternative hearing reconstruction technique in cases of type 3 tympanoplasty.

Radiesse for Aesthetic Soft Tissue Augmentation

Introduction:

Calcium hydroxyapatite (CaHa; also spelled “hydroxylapatite”) is the main mineral component of bone, calcified cartilage, and teeth. It has been used since the 1970s in many specialties, including orthopedics, urology, otolaryngology, maxillofacial surgery, and radiology, as a bioactive implant that promotes chemical attachment of the soft tissue to its surface. In 2001, Radiance FN (now Radiesse) was introduced as a CaHa-based product and approved by the US Food and Drug Administration (FDA) as a radiographic tissue marker, for soft tissue vocal fold augmentation, and for implants in maxillofacial defects. Currently, it is also used outside the United States and off-label in the United States for facial soft tissue augmentation. Microspheres of CaHa are suspended in a mixture of water, glycerin, and carboxymethylcellulose gel that provides a scaffold for tissue infiltration. Once injected, the gel is degraded and the CaHa infiltrates the surrounding cells. CaHa is nonirritating, and the carrier gel components are classified as safe by the FDA. Although a great variety of fillers are currently on the market, CaHa (Radiesse) has demonstrated the longest duration in tissue without any reports of antigenicity, migration, or granuloma formation. In this study, we report our experience with CaHa (Radiesse) for aesthetic soft tissue augmentation.

Materials and Methods:

A total of 139 patients were treated over an 18-month period at 2 private offices in Argentina and the United States. Exclusion criteria included previous use of permanent tissue fillers in the treatment area. Patients with previous use of hyaluronic acid fillers in the treatment area (up to 1 year prior to the study) were allowed to participate in the study. Radiesse was injected from 1-mL prefilled syringes with 27½-gauge needles in different areas such as nasolabial folds, lips, marionettes lines, cheeks, and cellulite dimples. Patient satisfaction and adverse effects were assessed by both physicians and patients during the procedure and during follow-up visits up to 1 year later.

Results:

Minimal pain, erythema, edema, and bruising were noted during and immediately after the procedure. All of the patients treated were satisfied with their results after one visit. There were no long-term adverse effects during the study period or on follow-up visits. Evaluation of 75% of the patients 1 year after treatment revealed persistence of filling effects.

Discussion:

CaHa used for aesthetic soft tissue augmentation yields immediate clinical results with high patient satisfaction.

Long-term Results with Hydroxylapatite Middle Ear Implants

PURPOSE: This study evaluated long-term results in patients who had ossicular reconstruction with a Goldenberg hydroxylapatite implant.

METHODS: A total of 233 patients underwent implantation; of these, 77 had 5-year or longer follow-up and are the subjects of this study of long-term hearing results. All 233 patients were included for analysis of extrusion rate and postoperative otorrhea.

RESULTS: The hearing success rate at long-term follow-up was 56.8%; the mean air-bone gap was 21.1 dB. Prosthesis extrusion occurred in 5.29% of the 233 patients, and visible slippage occurred in 7.7%. Overall, 50.6% of patients met the criteria for successful hearing, which included no extrusion and a dry ear. Better hearing before surgery and presence of the malleus long process were factors associated with a successful hearing result, as was tympanoplasty alone and canal wall up tympa-nomastoidectomy.

CONCLUSION: Hydroxylapatite hybrid prostheses provide stable hearing results over time with low extrusion and a dry ear overall.

Study on effects of partial ossicular replacement prostheses with different materials on hearing restoration

Numerical simulation method was used in this paper to study the effects of partial ossicular replacement prostheses (PORPs) with different materials on hearing restoration, from the biomechanical point of view. According to the CT scan imagery of the right ear from a normal human body, the CT data was digitalized and imported into PATRAN to establish a three dimension finite element model by self-compiling program, and then a frequency response analysis was made for the model. The calculated results were compared with experiment data to verify the correctness of the numerical model. Based on this, human numerical model of PORPs was established to make dynamic calculation of sound conduction and analyse the effects of PORPs with different materials on hearing restoration. The following conclusions are obtained : From the angle of dynamical behaviors in sound conduction process of human ear, in different frequency bands of the same sound pressure, PORPs with different materials have different effects on hearing restoration. A better sound transmission in low frequencies is obtained by PORPs with hydroxyapatite ceramics, stainless steel. In high frequencies, better sound transmission is gained by PORPs with porous polyethylene. In the 500-3,000 Hz range which is clinicians typically measure and pay attention to, better sound transmission is gained by PORPs with alumina ceramics, hydroxyapatite ceramics, EH composite materials and porous polyethylene. There are three materials which has an obvious potential to provide more hearing restoration than another between 500 and 3,000 Hz. The hearing restoration value of hydroxyapatite ceramics is 7.1 dB larger than that of stainless steel. The hearing restoration value of titanium is 4.9 dB larger than that of stainless steel. Hydroxyapatite ceramics has better effects on sound transmission than titanium and other materials.

Hearing Results Post Tympanoplasty: Our Experience with Adults at the KKR ENT Hospital, India

Chronic suppurative otitis media is often associated with some degree of hearing loss. Tympanomastoid surgery is considered effective in controlling infection and preventing recurrence. However, opinions differ with regards the post-operative hearing results. This study aims to assess the hearing results, and also ascertain the effects of some variables on hearing in adult patients with chronic suppurative otitis media after primary tympanoplasty. This was a retrospective review of the clinical records of adult patients with chronic suppurative otitis media, who had primary tympanoplasty at the KKR ENT Hospital and Research Institute in Chennai (India), between 1st June and 30th September, 2011. A total of 26 adult patients with a mean age of 35.85 years (SD 14.775) were studied. There were 16 males (61.54 %) and 10 females (38.46 %). The commonest presenting symptoms were ear discharge (80.8 %) and hearing loss (76.9 %); and the mean duration of symptom was 8.52 years (SD 8.599). The overall mean pre-operative pure tone average was 49.58 dB (SD 18.608), while the overall mean post-operative pure tone average was 37.38 dB (SD 17.837). The difference between the overall mean pre- and post-operative pure tone average (hearing gain) was 12.192 dB (SD 12.924); and this was found to be statistically significant (p < 0.05). Multiple linear regression model showed that only increasing age was significantly associated with increasing mean post-operative pure tone average. This study found primary tympanoplasty effective in improving hearing results in adults with chronic suppurative otitis media even in those with advanced ossicular lesions.

Malleus-to-Footplate versus Malleus-to-Stapes-Head Ossicular Reconstruction Prostheses: Temporal Bone Pressure Gain Measurements and Clinical Audiological Data

HYPOTHESIS

Several clinical reports suggest that if the stapes superstructure is intact, ossicular reconstruction should be made to the stapes head rather than the footplate to achieve a better hearing outcome. To test this hypothesis, we compared the in situ mechanical performance of hydroxylapatite (HA) malleus-to-stapes-head (MSH) ossicular reconstruction prosthesis (ORP) with malleus-to-footplate (MFP) ORP, both manufactured by Project HEAR.

BACKGROUND

ORPs are commonly used to replace a missing or deficient incus. However, hearing outcomes are highly variable, depending on the ORP material, design, surgical technique, and ORP positioning.

METHODS

Cochleo-vestibular pressure measurements in human cadaveric temporal bones for the HA MFP ORP have been reported by Puria et al. (2005). In the present study, the ear canal pressure Pe and cochleovestibular pressure Pv were measured in cadaveric temporal bones with intact incus, removed incus, and MSH ORP reconstruction. The relative loss in gain, Lmsh, is defined as the ratio of Pv with reconstructed MSH ORP to intact incus and compared with Lmfp. A retrospective clinical audit of the pre- and postoperative audiologic results of patients who had undergone ossiculoplasty with either MSH or MFP ORP was conducted for comparison.

RESULTS

For the 0.5 to 3 kHz frequency range, Lmsh magnitude is 6.2 dB lower than the Lmfp magnitude (p = 0.05). The retrospective audit of audiologic results after ossiculoplasty with either MSH or MFP ORP revealed a similar difference in gain between the two ORP designs with air-bone gap differences of 7.6 dB (p = 0.04) and air conduction threshold differences of 8.0 dB (p = 0.13) for these patients.

CONCLUSION

The MFP ORP showed better average pressure gain compared with the MSH ORP across the speech frequencies. Surgeons performing ossiculoplasty with designs similar to Project HEAR HA ORPs, where there is direct columella-like connection between the malleus and stapes, should consider using the MFP ORP design to achieve a better postoperative audiologic result, even when the stapes superstructure is intact.

Reconstruction of the entire ossicular conduction mechanism

OBJECTIVES/HYPOTHESIS

Stapes fixation combined with fixation, absence, or malformation of the malleus-incus complex requires an uncommon surgical reconstruction and offers a unique combination of challenges and hazards. This situation may occur in the presence of severe tympanosclerosis, otosclerosis, congenital ossicular malformations, and revision surgery for either stapedectomy or chronic ear disease. In previous reports, this procedure has been grouped with total ossicular reconstruction without much distinction. However, the challenges unique to this problem deserve special consideration. The present report offers a treatment plan for a group of patients requiring reconstruction of the entire ossicular conduction mechanism including removal of the stapes footplate.

STUDY DESIGN

Retrospective review.

METHODS

Three thousand three hundred fifty (3350) charts of patients requiring total ossicular replacement prostheses (TORPs) were reviewed. Of this group of patients, only 21 of 3350 patients from 1977 to 1999 required TORP placement and removal of the stapes footplate. The patients were followed for an average period of 50 months.

RESULTS

Hearing results indicated an overall improvement in the air-bone gap of 10 dB, with 52% achieving an air-bone gap of less than 20 dB. Of the 21 cases, 5 revision surgeries were performed. Three were performed because of a displaced TORP (14.2%). and 2 were performed because of extruded TORPs (9.5%).

CONCLUSIONS

Reconstruction of the entire ossicular conduction mechanism including removal of the stapes footplate can be successfully achieved with improvement of the air-bone gap of less than 20 dB. Hearing results and extrusion rates are comparable to reported results of TORP placement on a mobile footplate. Successful stapedectomy and simultaneous ossicular chain reconstruction can be performed as a single or staged procedure. Special attention is paid to avoid intrusion of the prosthesis into the vestibule.

Extrusion rates and hearing results in ossicular reconstruction

OBJECTIVES

To examine hearing results, extrusion rates, and factors likely to affect outcome in patients who underwent ossicular chain reconstruction with Plasti-Pore and hydroxylapatite total ossicular replacement prostheses (TORPs) and partial ossicular replacement prosthesis (PORPs).

STUDY DESIGN AND SETTING

Retrospective chart review was used. Subjects were 1210 consecutive tympanoplasties with or without mastoidectomy that involved ossicular reconstruction with TORPs (n = 560) or PORPs (n = 650) performed in a tertiary referral neurotologic private practice. Only 20% of the cases were primary surgeries, with the majority planned second stage or revision procedures.

RESULTS

Average last postoperative air-bone gap (ABG) was 19.2 dB with closure of the ABG to within 20 dB in 62.9%. Hearing results were better for cases who had not had previous surgery, in those with a diagnosis other than chronic otitis media, when a cartilage graft was used, and for Plasti-Pore rather than hydroxylapatite. Extrusion was known to occur in 4%.

CONCLUSION

After more than 25 years of use in our clinic, Plasti-Pore ossicular replacement prostheses continue to provide reliable hearing results with a low rate of extrusion.

Evaluation of hydroxyapatite ossicular chain prostheses

Hydroxyapatite (HA) middle ear prostheses have gained popularity as an alternative to human autografts and homografts. This study reports on 3 HA prostheses types: total ossicular chain prostheses, used for grafting the stapes footplate to the tympanic membrane; partial ossicular chain prostheses, used for grafting the stapes superstructure to the tympanic membrane; and Kartush incus struts (Smith & Nephew Richards Inc), used for grafting the stapes superstructure to the undersurface of the malleus. This single-surgeon study of 33 consecutive cases revealed a statistically significant difference in mean postoperative air-bone gap and airbone gap closure between incus struts (14/26 dB) or partial (22/11 dB) or total (25/10 dB) ossicular chain prostheses (t test: P<0.05). Prognostic risk factors graded by the Middle Ear Risk Index indicate a tendency for worse postoperative hearing with increasing Middle Ear Risk Index. This study supports the use of HA ossicular prostheses and, in particular, the use of the malleus for ossicular chain construction.

Ossiculoplasty using hydroxyapatite prostheses: long-term results

The surgical results of ossicular chain reconstruction using a hydroxyapatite prosthesis were evaluated in 106 ears of 101 patients who were followed up for > 5 years. Successful reconstruction was defined as: (1) postoperative air-bone gap of </= 20 db; or (2) postoperative air conduction better than 40 db; or (3) hearing gain better than 15 db. Success in hearing was obtained in 63/106 ears (59%) at 1 year; 44/65 ears (68%) in P-type (short columella) and 19/41 ears (46%) in T-type (long columella). By the fifth year, the overall success rate had deteriorated to 50%: i.e. 39/65 ears (60%) in P-type and 14/41 ears (34%) in T-type. Extrusion of the prosthesis occurred in 17 ears (16%) with a mean postoperative period of 27.7 months. The present results indicate that hydroxyapatite is a suitable material for an ossicular prosthesis, although the incidence of extrusion is high when it is placed in contact with the tympanic membrane.

Long-term results with hydroxylapatite middle ear implants

PURPOSE

This study evaluated long-term results in patients who had ossicular reconstruction with a Goldenberg hydroxylapatite implant.

METHODS

A total of 233 patients underwent implantation; of these, 77 had 5-year or longer follow-up and are the subjects of this study of long-term hearing results. All 233 patients were included for analysis of extrusion rate and postoperative otorrhea.

RESULTS

The hearing success rate at long-term follow-up was 56.8%; the mean air-bone gap was 21.1 dB. Prosthesis extrusion occurred in 5.29% of the 233 patients, and visible slippage occurred in 7.7%. Overall, 50. 6% of patients met the criteria for successful hearing, which included no extrusion and a dry ear. Better hearing before surgery and presence of the malleus long process were factors associated with a successful hearing result, as was tympanoplasty alone and canal wall up tympanomastoidectomy.

CONCLUSION

Hydroxylapatite hybrid prostheses provide stable hearing results over time with low extrusion and a dry ear overall.

CT evaluation of prosthetic ossicular reconstruction procedures: what the otologist needs to know

Postoperative otologic evaluation of patients who have undergone ossicular reconstruction is often difficult. However, thin-section computed tomography (CT) can help determine the type of prosthesis used for reconstruction and adequately assess for complications that may be causing postoperative conductive hearing loss. A variety of prostheses may be used in ossicular reconstruction (eg, stapes prosthesis, incus interposition graft, Applebaum prosthesis, Black oval-top prosthesis, Richards centered prosthesis, Goldenberg prosthesis) and can usually be identified at CT by their shapes and locations. Several causes of prosthetic failure are readily demonstrated at CT, including recurrent cholesteatoma and otitis media, formation of granulation tissue or adhesions, and various mechanical problems (eg, subluxation, dislocation, extrusion, fracture, bending). Perilymphatic fistula can be difficult to identify at CT but may be suggested by the presence of pneumolabyrinth, unexplained middle ear effusion, or fluid accumulation within the mastoid air cells. The presence of soft tissue within the oval window niche 4-6 weeks following surgery may indicate poststapedectomy granuloma or fibrosis. Familiarity with the normal and abnormal CT appearances of ossicular prostheses will enable the radiologist to assist the otologist in identifying patients in whom revision surgery is most appropriate.

Hearing results in pediatric patients with chronic otitis media after ossicular reconstruction with partial ossicular replacement prostheses and total ossicular replacement prostheses

OBJECTIVE

To examine hearing results in pediatric patients after ossicular reconstruction with partial ossicular replacement prostheses (PORPs) and total ossicular replacement prostheses (TORPs) in children with chronic otitis media.

METHODS

A retrospective chart review was performed on 55 pediatric patients with chronic otitis media who underwent ossicular reconstruction from 1991 to 1998. Patients' audiograms were evaluated preoperatively and postoperatively for pure-tone average (PTA), air-bone gap (ABG), speech reception threshold (SRT), method of ossicular reconstruction, and management of the mastoid.

RESULTS

Twenty-seven patients underwent ossicular reconstruction with TORPs. The average preoperative ABG was 40.1 dB, and the average postoperative ABG was 31.6 dB. Forty-one percent of the children improved their PTA greater than 10 dB postoperatively, and 52% of children did not change their ABG by more than 10 dB postoperatively. Nineteen percent of children with TORPs had a postoperative ABG less than 20 dB, and 44% of children with TORPs had a postoperative ABG less than 30 dB. Twenty-eight patients underwent ossicular reconstruction with PORPs. The average preoperative ABG was 29.7 dB, and the average postoperative ABG was 22.5 dB. Thirty-two percent of patients improved their PTA by greater than 10 dB, while 57% of children with PORPs did not change their ABG by more than 10 dB postoperatively. Forty-three percent of children with PORPs had an ABG of less than 20 dB postoperatively, and 71% of children with PORPs had a postoperative ABG less than or equal to 30 dB.

CONCLUSIONS

Children who underwent ossicular reconstruction with PORPs had slightly better postoperative hearing than did children with TORPs. Postoperative hearing was essentially unchanged in approximately 55% of both groups. Preoperative hearing levels may be the most important factor determining postoperative hearing in nonstaged surgery for children with chronic otitis media Long-term hearing results in children with single-stage surgery were not as good as those reported in the literature for staged surgery. Severe mucosal disease and eustachian tube dysfunction may contribute to poorer hearing results in children.

Ossiculoplasty in young children with the Applebaum incudostapedial joint prosthesis

OBJECTIVE

To evaluate the performance of the Applebaum incudostapedial joint prosthesis in young children in terms of hearing results and long-term stability despite continuing eustachian tube dysfunction and otitis media.

STUDY DESIGN

Retrospective review of all Applebaum prostheses placed in children at our institution from June 1993 to June 1998.

RESULTS

In 1993 Applebaum proposed the use of a hydroxylapatite ossicular prosthesis as an alternative to incus interposition for the repair of incudostapedial discontinuity. We have used this prosthesis exclusively for the repair of such defects in children over the past 5 years. Among 12 operated ears, all healed, all prostheses remain in place (average duration, 2.6 y), and all children have excellent hearing (mean air-bone gap, 15 dB; range, 5-25 dB).

CONCLUSIONS

The Applebaum incudostapedial joint prosthesis restores conductive hearing even in young children. It has been stable in the face of recurrent otitis media and has not interfered with revision surgery. Placement of the prosthesis at primary cholesteatoma surgery should be considered in children.

Thickness of fibrous capsule after implantation of hydroxyapatite in subcutaneous tissue in rats

The present study evaluates in rats the histomorphometrical thickness of fibrous capsules that surround hydroxyapatite (HA) disks after implantation. HA disks were implanted into the subcutaneous tissue of 79 rats for 1 day to 20 months. Decalcified histological sections stained with hematoxylin and eosin were examined. Fibrous capsule thickness (FCT) was measured using an objective micrometer. On the fourteenth day, primary fibrous capsules formed around implants. From that time point FCT increased with time of implantation. Within a given sample, FCT differed from one portion of the fibrous capsule to another, depending on which site faced the disks. FCT was thickest at the upper and lower portions of the disks, thinner at the lateral portions, and thinnest at the upper and lower ring-shaped portions. Two possible explanations for the above findings are discussed in this paper: (1) The area of contact between disk and tissue differs. (2) Chemical stimulation of implanted material caused by demineralization and remineralization may result from the varying thicknesses of fibrous capsules. FCT from upper and lower portions of HA disks increased by over 200% in the first 10 months and steadily increased about 20% over the next 10 months. Many studies have concluded that HA is useful for reconstructive surgery, so the long-term effects of FCT need further study.

Double cartilage block ossiculoplasty in chronic ear surgery

OBJECTIVES/HYPOTHESIS

Multiple techniques of ossicular reconstruction have been advocated for hearing rehabilitation in the setting of chronic otitis media No single method can adequately address the clinical spectrum of disease severity. In the situation of a severely diseased ear requiring a canal wall down (CWD) mastoidectomy in the presence of an intact stapes superstructure, the authors have employed a double cartilage block (DCB) ossiculoplasty. The technique and short-term results are reviewed.

STUDY DESIGN

Retrospective chart review in a tertiary referral otologic practice.

METHODS

Twenty-three patients underwent a CWD tympanomastoidectomy with DCB ossiculoplasty. Ages ranged from 6 to 85 years (mean, 36.1 y). The majority of ears were actively draining at the time of surgery (83%) and most procedures were revisions of prior mastoidectomies (74%). Audiometric data (mean postoperative follow-up, 19.5 mo) were calculated according to 1995 American Academy of Otolaryngology-Head and Neck Surgery guidelines.

RESULTS

Audiometric results were available in 20 patients. The mean air-bone gap (ABG) was 23.8 dB after surgery. Closure of the ABG to within 20 dB was achieved in 10 of 20 patients (50%). No cases of DCB extrusion have occurred to date.

CONCLUSIONS

The DCB represents an excellent alternative to biocompatible prostheses for ossicular reconstruction in the setting of severe chronic ear disease. As with all methods of ossiculoplasty, long-term follow-up will be necessary to determine if this technique remains stable in the hostile environment in which it has been employed.

Functional results of Plastipore prostheses for middle ear ossicular chain reconstruction

OBJECTIVE

Assessment of plastipore prostheses for middle ear ossicular chain reconstruction. Hearing results with total and partial Plastipore ossicular replacement prostheses (TORP and PORP) were evaluated in open- and closed-cavity operations.

STUDY DESIGN

A retrospective review of 237 patients who underwent operation for chronic ear disease as well as ossiculoplasty with plastipore prostheses. In order to assess the functional results, only 156 of 237 patients were included in the study. Follow-up ranged from 6 to 46 months.

METHODS

Canal wall up and canal wall down operations were performed. Either TORP or PORP ossiculoplasty was performed in each operation. An airbone gap closure to within 20 dB was considered successful.

RESULTS

With TORPs, the airbone gap closure to within 20 dB was achieved in 43.1%, and similar results were obtained with PORPs in 63.3%. In canal wall down and canal wall up operations, the success rates were 55.8% and 55.7%, respectively. The best results were obtained with PORPs in canal wall down operations, with a success rate of 82%. The extrusion rate of the prostheses was 4.2%.

CONCLUSION

Hearing results of PORPs are better than TORPs. In canal wall up and canal wall down operations similar hearing results are obtained. PORP ossiculoplasty in a canal wall down operation yields the most favorable hearing result.

Partial ossicular reconstruction in children: a review of 62 operations

OBJECTIVE/HYPOTHESIS

The published experience and audiometric results with ossicular reconstruction in children are limited. To better understand the role of ossiculoplasty in children, audiometric results were examined for partial ossicular reconstructions performed on a pediatric population.

STUDY DESIGN

Retrospective.

METHODS

Sixty-two partial ossicular reconstructions performed on a pediatric population were reviewed for audiometric results, prosthesis extrusion rates, and mechanisms of failure at revision. Comparison of techniques and prosthesis types: porous polyethylene partial ossicular replacement prosthesis (POP), Schuring ossicle cup (SOC), and modified Robinson prosthesis (MRP) were also evaluated. Follow-up ranged from 6 to 72 months.

RESULTS

Six-month hearing results showed postoperative airbone gaps less than or equal to 20 dB in 77% of cases. Successful results at 1 and 2 years were retained in 66% and 63% of cases, respectively. Results for POPs at 1 and 2 years were 78% and 89%. Results for SOCs at 1 and 2 years were 61% and 55%. The overall extrusion rate was approximately 3%.

CONCLUSIONS

These results compare favorably with those from other, mostly adult, studies. Comparison of prosthesis types revealed generally stable long-term results with few significant differences. Success with ossiculoplasty in children can be obtained by applying the same principles and approach to ossicular reconstruction as used in adults. Ossicular reconstruction in children remains a secondary goal after establishing a safe, dry, and stable ear. A discussion of techniques and comparative literature review are presented.

Toynbee Memorial Lecture 1997. Middle ear mechanics in normal, diseased and reconstructed ears

A review of the structure-function relationships in normal, diseased and reconstructed middle ears is presented. Variables used to describe the system are sound pressure, volume velocity and acoustic impedance. We discuss the following: (1) Sound can be transmitted from the ear canal to the cochlea via two mechanisms: the tympanoossicular system (ossicular coupling) and direct acoustic stimulation of the oval and round windows (acoustic coupling). In the normal ear, middle-ear pressure gain, which is the result of ossicular coupling, is frequency-dependent and smaller than generally believed. Acoustic coupling is negligibly small in normal ears, but can play a significant role in some diseased and reconstructed ears. (2) The severity of conductive hearing loss due to middle-ear disease or after tympanoplasty surgery can be predicted by the degree to which ossicular coupling, acoustic coupling, and stapes-cochlear input impedance are compromised. Such analyses are used to explain the air-bone gaps associated with lesions such as ossicular interruption, ossicular fixation and tympanic membrane perforation. (3) With type IV and V tympanoplasty, hearing is determined solely by acoustic coupling. A quantitative analysis of structure-function relationships can both explain the wide range of observed post-operative hearing results and suggest surgical guidelines in order to optimize the post-operative results. (4) In tympanoplasty types I, II and III, the hearing result depends on the efficacy of the reconstructed tympanic membrane, the efficacy of the reconstructed ossicular chain and adequacy of middle-ear aeration. Currently, our knowledge of the mechanics of these three factors is incomplete. The mechanics of mastoidectomy and stapedectomy are also discussed.

Hearing results with the Dornhoffer ossicular replacement prostheses

The "ideal" prosthesis for ossicular reconstruction should, from a surgical standpoint, require easy manipulation, reduce surgeries to partial or total variants, and be constructed of stable, biocompatible material. From an acoustic standpoint, a prosthesis should weigh 10 to 40 mg, provide proper tension between the tympanic membrane (TM) and stapes, form less than a 30-degree angle with the TM, and accommodate the malleus. Work was conducted with Smith & Nephew Richards, Inc. (Memphis, TN), to develop a partial ossicular replacement prosthesis (PORP) and a total ossicular replacement prosthesis (TORP) that combined the majority of these features. This retrospective study used a computerized otologic database to identify patients implanted with a Dornhoffer HAPEX PORP or TORP from June 1995 to March 1997. The surgical procedures utilizing these prostheses were primary cholesteatoma and revision surgery of previously performed modified or radical mastoidectomies complicated by poor hearing or chronically draining cavities. Preoperative and postoperative air and bone conduction four-frequency (500, 1000, 2000, and 3000 Hz) pure-tone averages (PTAs) were used to calculate the PTA air-bone gaps (ABGs). Results in 52 cases (follow-up, 1 year) showed a statistically significant improvement in hearing (P < 0.05) for each group. Excellent hearing results (< or = 10 dB PTA-ABG) were seen in 69% of PORP cases and in 35% of TORP cases, and good results (11 to 20 dB PTA-ABG) were seen in 31% and 50% of PORP and TORP cases, respectively. Designing an ossicular replacement prosthesis with both surgical and acoustic factors in mind has led to encouraging short-term hearing results.

Long-term observation of subcutaneous tissue reaction to synthetic auditory ossicle (Apaceram) in rats

The present study evaluates histological characteristics of the soft tissue response to long-term implantation of Apaceram discs composed of dense hydroxyapatite in rats. Discs were implanted into the subcutaneous tissue of 76 rats for six to 20 months. Decalcified histological sections stained with haematoxylin and eosin (H & E) and Mallory's azan were examined. Different cell types surrounding implants were counted. The greatest proportion of macrophages was found at six months (13.5 per cent). This proportion gradually decreased to four per cent at 20 months. Small numbers of lymphocytes and foreign body giant cells were observed in every group, but neither neutrophils nor osteogenesis were observed in any specimens. Results of the present study and previous related studies indicate that despite reappearance of a small number of macrophages six months after implantation, Apaceram is useful for reconstructive surgery.

Subcutaneous tissue reaction to synthetic auditory ossicle (Apaceram) in rats

A study was carried out in order to obtain further information about the soft tissue response to thin Apaceram discs of dense hydroxyapatite (HA) implanted in rats for various periods of time between one day and 10 months. The Apaceram discs were implanted subcutaneously into the interscapular region of 33 rats. A sham operation was performed on eight rats used as controls. Decalcified histological sections stained with haematoxylin and eosin and Mallory's azan were examined and the different cell types found around the implants were counted. It was found that an acute inflammatory reaction occurred after one day and disappeared at about two weeks after implantation. In the test groups, macrophages and lymphocytes disappeared about one week later, and no inflammatory reaction was observed from one to three months. However, a tissue reaction occurred at six months with the appearance of macrophages and lymphocytes, and decreased gradually at 10 months. Meanwhile, a few foreign body giant cells at the Apaceram-tissue interface and a thick layer of fibrous connective tissue around the Apaceram disc were observed at 10 months. No osteogenesis was observed in any specimen. The results obtained so far suggest that Apaceram is still a useful material for reconstructive surgery, despite the possible appearance of a slight macrophage reaction at six months.