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MIDDLE EAR RECONSTRUCTIVE TECHNIQUES
OTITIS MEDIA: SURGICAL PRINCIPLES BASED ON PATHOGENESIS
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MIDDLE EAR RECONSTRUCTIVE TECHNIQUES Richard A. Chole, MD, PhD, and Douglas J. Skarada, MD
HISTORY OF OSSICULOPLASTY
Wiill~tein~~ undertook reconstruction of the sound-conducting apparatus in 1956 when he proposed five classes of tympanoplasty. He reestablished sound conduction by medializing the tympanic membrane to the remaining ossicular chain or oval window. At approximately the same time, Hall and RytznerI4described the stapedectomy and autotransplantation of ossicles in which either the incus or the malleus was removed then reintroduced as a connection between the mobilized footplate of the stapes and the tympanic membrane. A comparison of the hearing results of these two developments confirmed the superiority of ossicular reconstruction over type 4 tympanoplasty, thus laying the foundation for the field of middle ear reconstructive surgery." In 1958, Sheaz8reported using polyethylene tubing over the head of the stapes and wedged under the tympanic membrane to rebuild the sound-conducting mechanism. This prompted interest in the development of synthetic material for ossicular reconstruction. Both the autograft and the synthetic graft procedures succeeded in closing the air-bone gap in the short-term but experienced significant drawbacks in the long term. For the autograft prostheses, these included displacement of the reconstruction, inability to reconstruct narrow oval window niches, and bony fixation. In 1976, SheaZ9implanted "biocompatible" prostheses, which showed short-term success; however, these synthetic prostheses suffered a high extrusion rate whenever they came in contact with the tympanic membrane. The unacceptable extrusion rate led Shea and Emmettz7to interpose a disk of cartilage between the head of the prosthesis and the tympanic membrane in 1978. Although this decreased the likelihood of extrusion, the cartilage disk did not eliminate it entirely4 This technique was extended when homologous cartilage
From the Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, Missouri
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was presculpted into a complete ossicular prosthesis. Thus extrusion was nearly eliminated because the structure was completely bi~compatible.~ Efforts to achieve a biocompatible synthetic prosthesis have led to the development of bioinert prostheses requiring tissue ingrowth for stabilization and bioactive prostheses attaining stabilization chemically. This article describes a series of common middle ear reconstructive scenarios and our recommendations for proven surgical solutions. The following scenarios are discussed: the mildly eroded incus, the absent incus, the absent incus and stapes suprastructure, absent stapes footplate, ossicular reconstructionin the presence of a perforated tympanic membrane, and selection of middle ear packing material.
CONTEMPORARY OSSICULOPLASTY
Numerous approaches to ossicular reconstruction have been shown to be successful in individual surgeon’s hands. No single technique has reached universal acceptance for two reasons. First, the preponderance of data consists of individual surgeons’ series using a specific technique as opposed to comparisons among multiple techniques. Second, the hearing results from these series are not reported in a uniform manner, making legitimate comparisons impossible. MonselP has proposed the following standardized approach in reporting results: (1)preoperative and postoperative air and bone conduction threshold data for 0.5-, 1.0-, 2.0-, 3.0-, and 4.0-kHz frequency by frequency; (2) postoperative results at 6 months, and 1,2,3,4, and five years; (3)extrusion rate at 5 years; and (4) disease variables, indications for surgery, staging, method of perforated tympanic membrane repair, condition of middle ear mucosa, status of eustachian tube function, management of canal wall, and amount of disease present. Table 1 shows the three general classes of prosthesis: autograft, homograft, and allograft. First, autograft prostheses include tissue harvested from the patient and used for reconstructing the ossicular chain. Examples of common autografts include rib cartilage, tragal cartilage, and incus. Second, homograft prostheses are derived from human donor tissue, screened and treated to avoid transmission of disease, and preserved for later use. Examples include tympanic membrane, total and partial cartilaginous reconstruction prostheses, and ossicles. Third, allograft prostheses are synthetic materials designed to be biocompatible. Materials used in allograft prostheses are numerous and are sometimes combined to maximize the benefits of each material and minimize their weaknesses. More recent materials include high-density polyethylene sponge (Plastipore),”maluminum oxide cer a m i ~ , ’ h~y, ~d ~ r o ~ y a p a t i t e and , ~ ~numerous ,~~ other^.^^,^,^^ The prostheses discussed in this article include autograft bone and tragal cartilage, homograft cartilage, and allograft hydroxyapatite. Discontinuity or fixation of the ossicular chain can cause conductive hearing loss. Discontinuity occurs in the following scenarios presented in order of frequency: eroded incudostapedial joint, absent incus, absent incus and stapes suprastructure, absent incus and stapes including the footplate.I8Any of these ossicular interruptions may include an absent malleus. Ossicular fixation most commonly occurs when the malleus head is ankylosed to the attic wall or when tympanosclerosis of the attic is present. The method of reconstruction depends on the ossicular defects encountered. The authors recommend the following strategies for middle ear reconstruction.
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Table 1. HEARING RESULTS FOR VARIOUS PROSTHESES
Material
Autogratt
Homogatt
Allograft
Extrusion rate
Very low
Very low
Low (whenever in contact with tympanic membrane)
Ease of handling
Technicallychallenging-must fashion intraoperatively
Technically straightforward-easily customized
Technically straightforward-select from various sizes
Availability
Must harvest and fashion
Immediately available
Immediately available
Operative time
Longest
Short
Short
Harvest
Easily modified
Fashion Reconstruct
Reconstruct
Select prosthesis size Reconstruct
Risk for residual disease
Possib1e
Unlikely
Unlikely
Risk of transmitting disease
None
Hypothetical
None
MILDLY ERODED INCUS
The incudostapedial joint and the lenticular process of the incus are the most common sites of ossicular discontinuity. This defect can lead to an air-bone gap of up to 60 dB. When erosion is limited to the most distal portion of the incus and when the incus and the malleus are mobile, the authors advise the following type of reconstruction. Applebaum' proposed a hydroxyapatite prosthesis for defects of the incus long process when discontinuity or mild continuity between the incus and stapes is present. Hydroxyapatite is a calcium phosphate ceramic with the molecular structure Ca,,(PO,),(OH),. Its similarity to bone may explain its apparent biocompatibility. Hydroxyapatite in the middle ear becomes encased in a mucosal envelope similar to bony prostheses. In this type of reconstruction, the hydroxyapatite does not contact the tympanic membrane; therefore, the possibility of extrusion is low. The Applebaum prosthesis is a rectangular piece of hydroxyapatite with a groove through the proximal end extending the length of the rectangle (Fig. 1). The groove stops short of penetrating the distal end of the rectangular prosthesis. At this distal end of the groove, a circular hole passes through the floor of the groove. The groove is designed to accommodate the remnant of the incus long process and permits visualization of long process during placement. The circular hole receives the stapes capitulum. The prosthesis is placed by gently lifting the long process of the incus and sliding it into the groove. Then the hole of the prosthesis is placed onto the stapes head. This procedure results in a stable connection requiring no further packing or tissue adhesion.
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Figure 1. A,The Applebaum prosthesis made of hydroxyapatite.B, The prosthesis bridges a defect between the incus and the stapes. (From Applebaum W L An hydroxylapatiteprosthesis for defects of the incus long process. Latyngoscope 103:330,1993; with permission.)
Advantages of the Applebaum prosthesis include: The prosthesis reliably bridges incus long process defects of up to 3 mm. It does not tend to loosen and lose continuity over time as in some traditional approaches. The prosthesis avoids technical difficulty and time involved in constructing bone or cartilage bridges. It precludes removal of the incus for refashioning, and consequently it spares unnecessary destruction of the incudomalleal joint. The prosthesis enjoys a biocompatibility advantage over stainless-steelprostheses that have a higher tendency to extrude. The prosthesis can be immediately available in the operating room, saving the patient from unnecessary anesthesia time. This allograft prosthesis avoids the hypothetical concern of disease transmission as in the use of banked human tissue. GroteI2has documented the hearing results for middle ear reconstruction with hydroxyapatite. Please refer to Table 2 for a comparison of the hearing results of hydroxyapatite with other reconstructive materials. ABSENT INCUS WITH STAPES INTACT
When the incus is absent or unsalvageable, the reconstructive approach involves partial ossicular reconstruction. Autograft prostheses in the form of an incus body interposition extending from the stapes to the manubrium or the tym, ~ ~ , ~ * prostheses panic membrane began to be used in the early 1 9 6 0 ~ . ’ ~ Sculptured evolved, including a “notched incus with short process” (used when the stapes suprastructure was present). This was the primary method for ossicular reconstruction used until the late 1980s. In 1976, Shea29introduced the ossicular reconstruction prosthesis, or ORP. Shea’s design featured a self-stabilizing upper platform that facilitated proper and secure placement of the prosthesis from the stapes to the tympanic membrane. These prostheses achieved excellent hearing results, but they suffered from a significant extrusion rate, even with interposition of tragal
I&.
w
W
Homologous cartilage
Homograft
Hydroxyapatite-Plastipore
Hydroxyapatite
~
~~~~
TOW POW Incus Incus/stapes Incus/stapes POW TOW Incus Incus-stapes Malleus-incus-stapes TOW/POW
Version
HEARING RESULTS FOR VARIOUS PROSTHESES
Plastipore prosthesis
Material
Table 2.
6 mo-4 y 6 mo-4 y 5Y 5Y 1Y 1Y 1Y 1Y 1Y 1Y 5 Y
Duration 416 407 120 50 All versions 186 As above As above 67 94 9 187
No. of Patients
8 6 0 4 4 4 4 NA NA NA 0
Extrusion (“YO)
55 73 83 76 50 43 30 90 83 100 65
%with Conductive Deficit <20 dB
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cartilage between the prosthesis and the tympanic membrane.4*31 The introduction of an entirely cartilage prosthesis virtually eliminated the persistent problem of allograft extrusion. The design followed Shea’s self-stabilizing c~nfiguration.~-~ Cartilage partial ORPs (PORPs) are commercially available.27They are constructed from rib cartilage harvested from cadaver organ donors, as depicted in Figure 2. The cartilage is acquired from donors aged 1 to 7 years. Twenty to 50 homograft prostheses are produced per donor rib cartilage. The cartilage is cut transversely into 8-mm segments. A 4-mm dermal punch is then used to create a cylinder. A 2-mm dermal punch then removes a core extending from one end to within 1 nun of the opposite end.5The prostheses are then placed in sterile saline specimen bottles and sterilized with 15,000 rad of gamma radiation. They are ready for immediate use without any further preparation. In the reconstructive scenario in which the stapes is intact with a mobile footplate and the incus is absent, a PORP configuration is used. Many are available, but the authors recommend the cartilage PORP for reconstruction. The surgical technique begins with measuring the distance from the lattermost aspect of the capitulum to the tympanic membrane. Approximately 0.5 mm is added to ensure firm contact between the prosthesis and the tympanic membrane. This avoids the complication of a short prosthesis lateralizing off of the capitulum. The cartilage blank is then trimmed to the appropriate length as depicted in Figure 3. A depression in the medial aspect of the cartilage blank is then created to receive the
I
JJ7I
0.5 mn
x o . 5 mn
Figure 2. Cartilage from costuchondral areas is presculpted into,a self-stabilizingcunfiguration. (From Chole RA: Ossicular replacement with self-stabilizing presculptured homologous cartilage. Arch Otolatyngol 108:560,1982;with permission.)
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A
H 2 mm
B
495
C
Figure 3.When a presculptedcartilage blank is used for PORP configuration, first the length of the shaft is shortened, and then an indentation is created in the end of the shaft to receive the stapes capitulum. If the platform of the prosthesis does not come into complete contact with the tympanic membrane because of tympanic membrane slope, then the platform can be angled (A). If the stapedial tendon inserts on the stapes capitulum high, then a small notch can be fashioned with scalpel or cutting bur (B). When significant mucosa is denuded from the middle ear, Gelfilm or Silastic is placed over the denuded mucosa and around the shaft of the implant to prevent adhesions (C). (From Chole RA, Hyung-jongK: Ossiculoplasty with presculptedbanked cartilage. OperativeTechniques in Otolaryngology-Head and Neck Surgely 7:38,1996; with permission.)
stapes capitulum. This depression is approximately 1 mm deep and 0.5 to 1.0 mm wide. At this time, the surgeon should consider creating a notch to accommodate the stapedial tendon whenever it inserts high on the stapes capitulum. When the malleus is present, the surgeon should consider tapering or trimming the lateral aspect of the platform anteriorly to permit positioning of the prosthesis next to the malleus handle, as depicted in Figure 4. When the malleus is absent, the platform may retain a flat top, as illustrated in Figure 5. The surgeon can attain added stabilization by creating contact between the prosthesis platform and the posterior bony annulus. When this is undertaken, the platform should be thinned at the site of contact to the bony annulus to minimize the formation of dense adhesions. The prosthesis should make approximately 0.5 mm of contact to the bony annulus. Sound conduction continues to work because of the flexibility of the cartilage. Ultimately, a thin fibrous sheath envelops the cartilage POW. This sheath secures the attachment of the prosthesis to the stapes capitulum. Cartilage PORPs demonstrate the following advantages: Nonmedical personnel process the donor tissue. The cartilage POW blanks can be stored in a tissue bank for long periods of time in sterile condition. Storage in the operating room makes them immediately available to the surgeon, saving the patient unnecessary anesthesia time. The cartilage POW blanks are easily sculpted into custom sizes and shapes for individual ears.
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Figure 4. When the malleus is present, the anterior most portion of the platform is tapered and trimmed to fit against the malleal handle. (From Chole RA, Hyung-jongK: Ossiculoplasty with presculptedbanked cartilage. OperativeTechniques in Otolaryngology-Head and Neck Surgery 7:38,1996; with permission.)
They are technically less demanding and faster than sculpting homograft ossicles during the surgical procedure. They consistently achieve excellent hearing results when in contact with adjacent bony walls because of the inherent cartilage flexibility. They benefit from Shea’s design to facilitate proper placement without risk of extrusion. The hearing results are stable over time unless severe infection or recurrent cholesteatoma is present. For the hearing results of cartilage prostheses compared with other prostheses, please refer to Table
Figure 5. When the malleus is absent, a flatter platform is used (compare with Fig. 4). (From Chole RA, Hyung-jongK: Ossiculoplasty with presculptedbankedcartilage. OperativeTechniques in Otolaryngology-Head and Neck Surgery 7:38,1996; with permission.)
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ABSENTINCUSANDSTAPESSUPRASTRUCTURE
Wide Oval Window Niche, Presculpted Cartilage Total Ossicular Replacement Prosthesis
When the incus and the stapes superstructure are absent, a total ossicular reconstruction must be undertaken. The surgeon should first assess the dimensions of the oval window niche before selecting a reconstructive approach. When a wide niche is present, the authors recommend using a cartilage total ossicular replacement prosthesis (TORPh6The surgeon undertakes measurements from the stapes footplate to the tympanic membrane and adds 0.5 mm. The cartilage blank is customized to that length. The same cartilage blank used for POW reconstruction is also used for TORP reconstruction. The shaft of the cartilage blank is then tapered to fit into the oval window niche, as demonstrated in Figure 6. The surgeon should be careful to avoid excessive thinning of the shaft because the prosthesis may lose structural integrity. The surgeon can modify the platform of the cartilage prosthesis to engage the malleus, to contact with the bony annulus, or to interface with the tympanic membrane without a malleus following the guidelines noted in the previous section. The cartilage TOW is not recommended when the oval window niche is narrow. Three reasons limit the use of the cartilage TORP in this scenario. First, the surgeon may not be able to adequately taper the shaft without losing structural integrity of the prosthesis. Second, fixation of the prostheses can occur if the shaft contacts the walls of the niche, as shown in Figure 7. Third, the surgeon’s view of the footplate may be completely obstructed by the platform of the prosthesis. Narrow Oval Window Niche, Goldenberg Total Ossicular Replacement Prosthesis
When the incus and stapes are absent and the oval window niche is narrow, the authors recommend using a composite prosthesis, such as Goldenberg’s flex-
Figure 6. When the banked cartilage is used in the total ossicular replacement prosthesis (TORP) configuration, the shaft of the prosthesis is tapered to fit into the oval window niche. (From Chole RA, Hyung-jongK: Ossiculoplastywith presculptedbanked cartilage.Operative Techniques in Otolaryngology-Head and Neck Surgery 7:38,1996; with permission.)
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Figure 7. When the oval window niche is very narrow, placement of the prosthesis is sometimes blind because the platform obstructs the surgeon’s view. Furthermore, adhesions may form between the walls of the niche and the shaft of the implant, thus impairingmobility. (From Chole RA, Hyung-jong K: Ossiculoplasty with presculpted banked cartilage. Operative Techniques in Otolaryngology-Head and Neck Surgery 7:38,1996; with permission)
ible hydroxyapatite prosthesis.’O The head of these prostheses are hydroxyapatite and designed with either a hook to accommodate the malleus when present or a flat elliptical design to interface directly with the tympanic membrane when the malleus is absent or too anteriorly positioned for use. The shaft is wire reinforced to add strength to the narrow profile. The surgical technique begins with measuring the distance from the tympanic membrane or the malleus to the footplate. The goal is to have slight tension between the head of the prosthesis and the tympanic membrane. The Plastiporeshaft of the incus-stapesprosthesis is trimmed to 0.5 mm longer to achieve slight tension when placed. The hydroxyapatite head is grasped with toothless forceps and a sharp blade is used to cut the shaft at a right angle. The prosthesis is then placed into the middle ear. If the malleus is present and its location relative to the oval window lends itself to incorporating it in the reconstruction, then the malleus is gently elevated and the hydroxyapatite hook is engaged, as depicted in Figure 8A. If the malleus cannot be used, the oval disk prosthesis is positioned under the tympanic membrane, as shown in Figure 8B. The shaft is placed on the stapes footplate. The amount of tension can be increased by sliding the head of the prosthesis to a position on the tympanic membrane closer to the oval window or decreased by positioning the prosthesis in more lateral regions of the tympanic membrane. The tympanic membrane can be repositioned to evaluate the final positioning of the prosthesis, and the round window reflex can be assessed. The authors prefer to add a thin tragal cartilage platform between the tympanic membrane and the hydroxyapatite head of the prosthesis to further decrease the possibility of extrusion. The middle ear space is packed with gelatin sponge to ensure stabilization. The primary advantage of the composite prosthesis is the ability to obtain a narrow prosthesis with sufficient structural integrity. The hydroxyapatite portion of the prosthesis is more biocompatible, and the shaft is easily customized in patients with a narrow oval window niche. Please refer to Table 2 for hydroxyapatite-PIastipore composite prosthesis hearing
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Figure 8. A, Positioning the incus-stapes prosthesis when the malleus is present. B, Positioning the incus-stapes prosthesis when the malleus is absent. (From Goldenberg RA: Ossiculoplastywith composite prostheses, PORP and TORP. OtolaryngolClin NorthAm 27:727, 1994; with permission.)
ABSENT STAPES FOOTPLATE
This surgical scenario occurs in a minority of cases. The surgical approach includes harvesting a perichondrial graft from the lateralmost aspect of the tragal cartilage. In this location, the perichondrium is stiff and thickened. These properties help to prevent displacement of the graft into the vestibule. Reconstruction should use the cartilage TORP or flexible hydroxyapatite TORP, as shown in Figure 9.6 OSSICULAR RECONSTRUCTION WHEN TYMPANIC MEMBRANE IS PERFORATED
Middle ear reconstruction is often necessary in the surgical scenario of a perforated tympanic membrane. The surgeon must assess the magnitude of the tympanic membrane perforation. When it is extensive, the surgeon may decide to stage the reconstruction, repairing the tympanic membrane and eradicating the disease with the first stage and then reconstructing the ossicular chain with the second stage. In most cases, both stages are performed at the same time. When a small perforation corresponds with placement of the disk-shaped cartilage platform of the prosthesis, the perforation may be grafted with the cartilage prosthesis,as seen
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Figure 9. A total ossicular replacement prosthesis (TORP) may be placed over the perichondrial graft in the absence of a stapedial footplate. (From Chole RA, Hyung-jong K: Ossiculoplasty with presculpted banked cartilage. OperativeTechniques in Otolaryngology-Head and Neck Surgery 7:38,1996;with permission.)
in Figure 10. This surface readily re-epithelializes, and further grafting is not necessary6 When the perforation is larger than the head of the cartilage prosthesis, the tympanic membrane requires grafting. The reconstruction options include temporalis fascia, tragal perichondrium, and tragal cartilage. MIDDLE EAR AERATION
Atelectasis of the middle ear is a challenging problem facing the surgeon. During middle ear surgery, the primary objective is eradication of disease. If the mucosa can be salvaged without risk for leaving residual disease, then this helps to minimize the possibility of the tympanic membrane scarring to bare bone. If the mucosa suffers only minimal damage, then middle ear packing material can provide a temporary barrier to adhesion of tympanic membrane to traumatized mucosa. When mucosa is removed during eradication of disease then packing material is essential. Common packing material includes gelatin sponge, silicone sheeting, and Gelfilm; each of these has advantages and disadvantages. Gelatin Sponge
Gelatin sponge (Gelfoam [Pharmacia and Upjohn, Bridgewater, NJ] purified pork-skin gelatin granules) is widely used to support middle ear surgery, but some studies question possible side effects. Animal studies suggest that Gelfoam may predispose to the formation of connective tissue, bone formation, and fibrosis.9,16,19,26 In some human studies, Gelfoam has been noted to predispose to granulation whereas in other studies, Gelfoam has been found to decrease the chance of developing granulation tissue.s
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:---
Implant may be used to graft a perforation Contact with annulus stabilizes implant but does not adversely
Implant may be trimmed
Figure 10. When there is a perforation in the tympanic membranethat correspondswith the placement of the prosthesis head then the platform of the prosthesis may serve as a graft for the perforation. (From Chole R A Ossiculoplasty with presculpted banked cartilage. Otolaryngol Clin North Am 27:717, 1994; with permission)
Silicone
Silicone (Silastic,Xomed-Treace, Jacksonville,FL)sheeting is a permanent and well-tolerated middle ear implant. Thin Silastic sheeting (0.013 mm) implanted into the middle ear prevents adhesion of the tympanic membrane graft to the promontory of the middle ear. Gelatin Sheeting
Gelatin sheeting (Gelfilm, Pharmacia and Upjohn, Bridgewater, NJ) is the same material as Gelfoam in a different structure. Gelfilm is constructed as a thin, transparent sheet. The use of Gelfilm is advised when extensive loss of mucosa has occurred. Some advantages of Gelfilm include: It avoids staged operations permitting eradication of disease and tympanoplasty in one stage. It is believed to promote mucosal healing before reabsorption.Reabsorption takes from 1 to 6 months in humans, depending on the size of Gelfilm and nature of the middle ear tissue. It decreases incidence of primary and late perforation. Although Silastic is well tolerated in the middle ear, it may extrude. It decreases the incidence of an immobile, retracted tympanic membrane adhering to the promontory. A comparison of absorbable gelatin sponge (Gelfoam), absorbable gelatin sheet (Gelfilm),and absorbable collagen sheet (Instat, Johnson and Johnson, Arlington, TX) reached the following conclusions. Gelfoam promotes fibrosis at a
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higher rate than control in the rat model, whereas Gelfilm and Instat do not promote fibrosis at a higher rate than normal. The suggested mechanism of fibrosis was Gelfoam serving as a scaffold for fibroblast growth between the promontory and the tympanic membrane or ossicular chain. The authors recommend the use of Gelfilm or Silastic sheeting when significant denuding of the mucosa has occurred, as depicted in Figure 3.
SUMMARY Middle ear reconstructive techniques have increased to such an extent that the otolaryngologist is faced with a bewildering number of surgical options. The literature has yet to demonstrate any technique to be optimal in every surgical scenario because of a lack of direct comparisons between techniques and dissimilar criteria for measuring success. This article uses hearing results and the ability to resist extrusion as the principal measures of success. This article provided middle ear reconstructive techniques proven to be successful for commonly faced surgical dilemmas.
References 1. Applebaum WL An hydroxylapatite prosthesis for defects of the incus long process. Laryngoscope 103:330,1993 2. Austin D F Ossicular reconstruction. Arch Otol9425, 1971 3. Brackmann DE, SheehyJL, Luxford WM: TORPs and POWs in tympanoplasty:Areview of 1042 operations. Otolaryngol Head Neck Surg 92:32,1984 4. Brackmann DE, Sheehy JL: Tympanoplasty TOWS and PORPs. Laryngoscope 89:108, 1979 5. Chole RA: Ossicular replacement with self-stabilizing presculptured homologous cartilage. Arch Otolaryngol 108:560, 1982 6. Chole RA: Ossiculoplasty with presculpted banked cartilage. Otolaryngol Clin North Am 27717,1994 7. Chole RA: Use of presculpted, banked cartilage transplants in ossicular reconstruction. Arch Otolaryngol Head Neck Surg 113:145,1987 8. Falbe-Hansen J, Tos M Silastic and gelatin film sheeting in tympanoplasty. Ann Otol Rhinol Laryngol84:315, 1975 9. Gjuric M: Aborbable gelatin sponge (marbagelan)in otosurgery: An experimentalstudy in the guinea pig. Laryngol Rhinol Otol66:186,1987 10. Goldenberg RA: Ossiculoplasty with composite prostheses, PORP and TOW. Otolaryngol Clin North Am 27727,1994 11. Gotay-Rodriguez VM, Schuknecht H F Experienceswith type IV tympanoplasty.Laryngoscope 87522,1977 12. Grote JJ: Reconstruction of the middle ear with hydroxylapatite implants: Long-term results. Ann Otol Rhinol Laryngol99:12, 1990 13. Guilford FR:Repositioning of the incus. Laryngoscope, 75:236,1965 14. Hall A, Rytzner C: Stapedectomyand autotransplantation of ossicles.Acta Otolaryngol (Stockh)47318,1957 15. Hall A, Rytzner C: Vitality of autotransplanted ossicles. Acta OtolaryngolSuppl (Stockh) 158335,1960 16. Hellstrom S, Salen B, Stenfors L: Absorbable gelatin sponge (gelfoam)in otosurgery:One cause of undesirable postoperative results? Acta Otolaryngol (Stockh)96:269, 1983 17. Hentrich RL, Graves GA, Stein HG, et a1 An evaluation of inert and resorbable ceramics for the future. J Biomed Mater Res 5:25, 1971 18. Hough J: Incudostapedial joint separation: Etiology, treatment and significances.Laryngoscope 69:644,1959
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19. Joseph R The effect of absorbable gelatin sponge preparations and other agents on scar formation in the dog's middle ear. Laryngoscope 72:1528,1962 20. Menvin G: Bioglass middle ear prosthesis: preliminary report. Ann Otol Rhinol Laryngol 95:78, 1986 21. Monsell EM: Results and outcomes in ossiculoplasty. Otolaryngol Clin North Am 27835, 1994 22. Ogawa S, Satoh I, Tanaka H: Patulous eustachian tube: A new treatment with insertion of aborbable gelatin sponge solution. Arch Otolaryngol Head Neck Surg 102:276,1976 23. Pauler M, Plenck H: Macor ceramics in soft and hard tissue. In Grote JJ (ed): Biomaterials in Otology. Boston, The Hague, Martinus Nijhoff Publishers, 1984, p 74 24. Plester D, Jahnke K Ceramic implants in otologic surgery. Am J Otol3:104, 1981 25. Reek R, Helms J: The bioactive glass ceramic cervital in ear surgery, five years' experience. Am J Otol6:280, 1985 26. Ribari 0, Jori J, Tomity J: Clinical and experimental studies on the incorporation of materials applied as covering for the labyrinth window. Acta Otolaryngol (Stockh) 89:384, 1980 27. Shea JJ, Emmett J R Biocompatible ossicular implants. Arch Otolaryngol104:191, 1978 28. Shea JJ: Fenestration of the oval window. Ann Otol Rhinol Laryngol67932,1958 29. Shea JJ: Plastipore total ossicular replacement prosthesis. Laryngoscope 86239,1976 30. Silverstein H, McDaniel AB, Lichtenstein R: A comparison of POW, TORE', and incus homograft for ossicular reconstruction in chronic ear surgery. Laryngoscope 96(2):159, 1986 31. Smyth GDL, Hassard TH, Kerr AG, et a1 Ossicular replacement prosthesis. Arch Otolaryngol 104:345, 1978 32. Van Blitterswijk CA, Grote JJ: Biocompatibility of clinically applied hydroxylapatite ceramic. Ann Otol Rhinol Laryngol, 99:12, 1990 33. Wiillstein H. Theory and practice of tympanoplasty. Laryngoscope 66:1076,1956
Address reprint requests to Richard A. Chole, MD, PhD Department of Otolaryngology-Head and Neck Surgery Washington University School of Medicine 517 South Euclid Avenue, Box 8115 St. Louis, MO 63110
0030-6665/99 $8.00 + .OO
MIDDLE EAR RECONSTRUCTIVE TECHNIQUES Richard A. Chole, MD, PhD, and Douglas J. Skarada, MD
HISTORY OF OSSICULOPLASTY
Wiill~tein~~ undertook reconstruction of the sound-conducting apparatus in 1956 when he proposed five classes of tympanoplasty. He reestablished sound conduction by medializing the tympanic membrane to the remaining ossicular chain or oval window. At approximately the same time, Hall and RytznerI4described the stapedectomy and autotransplantation of ossicles in which either the incus or the malleus was removed then reintroduced as a connection between the mobilized footplate of the stapes and the tympanic membrane. A comparison of the hearing results of these two developments confirmed the superiority of ossicular reconstruction over type 4 tympanoplasty, thus laying the foundation for the field of middle ear reconstructive surgery." In 1958, Sheaz8reported using polyethylene tubing over the head of the stapes and wedged under the tympanic membrane to rebuild the sound-conducting mechanism. This prompted interest in the development of synthetic material for ossicular reconstruction. Both the autograft and the synthetic graft procedures succeeded in closing the air-bone gap in the short-term but experienced significant drawbacks in the long term. For the autograft prostheses, these included displacement of the reconstruction, inability to reconstruct narrow oval window niches, and bony fixation. In 1976, SheaZ9implanted "biocompatible" prostheses, which showed short-term success; however, these synthetic prostheses suffered a high extrusion rate whenever they came in contact with the tympanic membrane. The unacceptable extrusion rate led Shea and Emmettz7to interpose a disk of cartilage between the head of the prosthesis and the tympanic membrane in 1978. Although this decreased the likelihood of extrusion, the cartilage disk did not eliminate it entirely4 This technique was extended when homologous cartilage
From the Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, Missouri
OTOLARYNGOLOGIC CLINICS OF NORTH AMERICA VOLUME 32. NUMBER 3 *JUNE 1999
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was presculpted into a complete ossicular prosthesis. Thus extrusion was nearly eliminated because the structure was completely bi~compatible.~ Efforts to achieve a biocompatible synthetic prosthesis have led to the development of bioinert prostheses requiring tissue ingrowth for stabilization and bioactive prostheses attaining stabilization chemically. This article describes a series of common middle ear reconstructive scenarios and our recommendations for proven surgical solutions. The following scenarios are discussed: the mildly eroded incus, the absent incus, the absent incus and stapes suprastructure, absent stapes footplate, ossicular reconstructionin the presence of a perforated tympanic membrane, and selection of middle ear packing material.
CONTEMPORARY OSSICULOPLASTY
Numerous approaches to ossicular reconstruction have been shown to be successful in individual surgeon’s hands. No single technique has reached universal acceptance for two reasons. First, the preponderance of data consists of individual surgeons’ series using a specific technique as opposed to comparisons among multiple techniques. Second, the hearing results from these series are not reported in a uniform manner, making legitimate comparisons impossible. MonselP has proposed the following standardized approach in reporting results: (1)preoperative and postoperative air and bone conduction threshold data for 0.5-, 1.0-, 2.0-, 3.0-, and 4.0-kHz frequency by frequency; (2) postoperative results at 6 months, and 1,2,3,4, and five years; (3)extrusion rate at 5 years; and (4) disease variables, indications for surgery, staging, method of perforated tympanic membrane repair, condition of middle ear mucosa, status of eustachian tube function, management of canal wall, and amount of disease present. Table 1 shows the three general classes of prosthesis: autograft, homograft, and allograft. First, autograft prostheses include tissue harvested from the patient and used for reconstructing the ossicular chain. Examples of common autografts include rib cartilage, tragal cartilage, and incus. Second, homograft prostheses are derived from human donor tissue, screened and treated to avoid transmission of disease, and preserved for later use. Examples include tympanic membrane, total and partial cartilaginous reconstruction prostheses, and ossicles. Third, allograft prostheses are synthetic materials designed to be biocompatible. Materials used in allograft prostheses are numerous and are sometimes combined to maximize the benefits of each material and minimize their weaknesses. More recent materials include high-density polyethylene sponge (Plastipore),”maluminum oxide cer a m i ~ , ’ h~y, ~d ~ r o ~ y a p a t i t e and , ~ ~numerous ,~~ other^.^^,^,^^ The prostheses discussed in this article include autograft bone and tragal cartilage, homograft cartilage, and allograft hydroxyapatite. Discontinuity or fixation of the ossicular chain can cause conductive hearing loss. Discontinuity occurs in the following scenarios presented in order of frequency: eroded incudostapedial joint, absent incus, absent incus and stapes suprastructure, absent incus and stapes including the footplate.I8Any of these ossicular interruptions may include an absent malleus. Ossicular fixation most commonly occurs when the malleus head is ankylosed to the attic wall or when tympanosclerosis of the attic is present. The method of reconstruction depends on the ossicular defects encountered. The authors recommend the following strategies for middle ear reconstruction.
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Table 1. HEARING RESULTS FOR VARIOUS PROSTHESES
Material
Autogratt
Homogatt
Allograft
Extrusion rate
Very low
Very low
Low (whenever in contact with tympanic membrane)
Ease of handling
Technicallychallenging-must fashion intraoperatively
Technically straightforward-easily customized
Technically straightforward-select from various sizes
Availability
Must harvest and fashion
Immediately available
Immediately available
Operative time
Longest
Short
Short
Harvest
Easily modified
Fashion Reconstruct
Reconstruct
Select prosthesis size Reconstruct
Risk for residual disease
Possib1e
Unlikely
Unlikely
Risk of transmitting disease
None
Hypothetical
None
MILDLY ERODED INCUS
The incudostapedial joint and the lenticular process of the incus are the most common sites of ossicular discontinuity. This defect can lead to an air-bone gap of up to 60 dB. When erosion is limited to the most distal portion of the incus and when the incus and the malleus are mobile, the authors advise the following type of reconstruction. Applebaum' proposed a hydroxyapatite prosthesis for defects of the incus long process when discontinuity or mild continuity between the incus and stapes is present. Hydroxyapatite is a calcium phosphate ceramic with the molecular structure Ca,,(PO,),(OH),. Its similarity to bone may explain its apparent biocompatibility. Hydroxyapatite in the middle ear becomes encased in a mucosal envelope similar to bony prostheses. In this type of reconstruction, the hydroxyapatite does not contact the tympanic membrane; therefore, the possibility of extrusion is low. The Applebaum prosthesis is a rectangular piece of hydroxyapatite with a groove through the proximal end extending the length of the rectangle (Fig. 1). The groove stops short of penetrating the distal end of the rectangular prosthesis. At this distal end of the groove, a circular hole passes through the floor of the groove. The groove is designed to accommodate the remnant of the incus long process and permits visualization of long process during placement. The circular hole receives the stapes capitulum. The prosthesis is placed by gently lifting the long process of the incus and sliding it into the groove. Then the hole of the prosthesis is placed onto the stapes head. This procedure results in a stable connection requiring no further packing or tissue adhesion.
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Figure 1. A,The Applebaum prosthesis made of hydroxyapatite.B, The prosthesis bridges a defect between the incus and the stapes. (From Applebaum W L An hydroxylapatiteprosthesis for defects of the incus long process. Latyngoscope 103:330,1993; with permission.)
Advantages of the Applebaum prosthesis include: The prosthesis reliably bridges incus long process defects of up to 3 mm. It does not tend to loosen and lose continuity over time as in some traditional approaches. The prosthesis avoids technical difficulty and time involved in constructing bone or cartilage bridges. It precludes removal of the incus for refashioning, and consequently it spares unnecessary destruction of the incudomalleal joint. The prosthesis enjoys a biocompatibility advantage over stainless-steelprostheses that have a higher tendency to extrude. The prosthesis can be immediately available in the operating room, saving the patient from unnecessary anesthesia time. This allograft prosthesis avoids the hypothetical concern of disease transmission as in the use of banked human tissue. GroteI2has documented the hearing results for middle ear reconstruction with hydroxyapatite. Please refer to Table 2 for a comparison of the hearing results of hydroxyapatite with other reconstructive materials. ABSENT INCUS WITH STAPES INTACT
When the incus is absent or unsalvageable, the reconstructive approach involves partial ossicular reconstruction. Autograft prostheses in the form of an incus body interposition extending from the stapes to the manubrium or the tym, ~ ~ , ~ * prostheses panic membrane began to be used in the early 1 9 6 0 ~ . ’ ~ Sculptured evolved, including a “notched incus with short process” (used when the stapes suprastructure was present). This was the primary method for ossicular reconstruction used until the late 1980s. In 1976, Shea29introduced the ossicular reconstruction prosthesis, or ORP. Shea’s design featured a self-stabilizing upper platform that facilitated proper and secure placement of the prosthesis from the stapes to the tympanic membrane. These prostheses achieved excellent hearing results, but they suffered from a significant extrusion rate, even with interposition of tragal
I&.
w
W
Homologous cartilage
Homograft
Hydroxyapatite-Plastipore
Hydroxyapatite
~
~~~~
TOW POW Incus Incus/stapes Incus/stapes POW TOW Incus Incus-stapes Malleus-incus-stapes TOW/POW
Version
HEARING RESULTS FOR VARIOUS PROSTHESES
Plastipore prosthesis
Material
Table 2.
6 mo-4 y 6 mo-4 y 5Y 5Y 1Y 1Y 1Y 1Y 1Y 1Y 5 Y
Duration 416 407 120 50 All versions 186 As above As above 67 94 9 187
No. of Patients
8 6 0 4 4 4 4 NA NA NA 0
Extrusion (“YO)
55 73 83 76 50 43 30 90 83 100 65
%with Conductive Deficit <20 dB
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cartilage between the prosthesis and the tympanic membrane.4*31 The introduction of an entirely cartilage prosthesis virtually eliminated the persistent problem of allograft extrusion. The design followed Shea’s self-stabilizing c~nfiguration.~-~ Cartilage partial ORPs (PORPs) are commercially available.27They are constructed from rib cartilage harvested from cadaver organ donors, as depicted in Figure 2. The cartilage is acquired from donors aged 1 to 7 years. Twenty to 50 homograft prostheses are produced per donor rib cartilage. The cartilage is cut transversely into 8-mm segments. A 4-mm dermal punch is then used to create a cylinder. A 2-mm dermal punch then removes a core extending from one end to within 1 nun of the opposite end.5The prostheses are then placed in sterile saline specimen bottles and sterilized with 15,000 rad of gamma radiation. They are ready for immediate use without any further preparation. In the reconstructive scenario in which the stapes is intact with a mobile footplate and the incus is absent, a PORP configuration is used. Many are available, but the authors recommend the cartilage PORP for reconstruction. The surgical technique begins with measuring the distance from the lattermost aspect of the capitulum to the tympanic membrane. Approximately 0.5 mm is added to ensure firm contact between the prosthesis and the tympanic membrane. This avoids the complication of a short prosthesis lateralizing off of the capitulum. The cartilage blank is then trimmed to the appropriate length as depicted in Figure 3. A depression in the medial aspect of the cartilage blank is then created to receive the
I
JJ7I
0.5 mn
x o . 5 mn
Figure 2. Cartilage from costuchondral areas is presculpted into,a self-stabilizingcunfiguration. (From Chole RA: Ossicular replacement with self-stabilizing presculptured homologous cartilage. Arch Otolatyngol 108:560,1982;with permission.)
MIDDLE EAR RECONSTRUCTIVE TECHNIQUES
A
H 2 mm
B
495
C
Figure 3.When a presculptedcartilage blank is used for PORP configuration, first the length of the shaft is shortened, and then an indentation is created in the end of the shaft to receive the stapes capitulum. If the platform of the prosthesis does not come into complete contact with the tympanic membrane because of tympanic membrane slope, then the platform can be angled (A). If the stapedial tendon inserts on the stapes capitulum high, then a small notch can be fashioned with scalpel or cutting bur (B). When significant mucosa is denuded from the middle ear, Gelfilm or Silastic is placed over the denuded mucosa and around the shaft of the implant to prevent adhesions (C). (From Chole RA, Hyung-jongK: Ossiculoplasty with presculptedbanked cartilage. OperativeTechniques in Otolaryngology-Head and Neck Surgely 7:38,1996; with permission.)
stapes capitulum. This depression is approximately 1 mm deep and 0.5 to 1.0 mm wide. At this time, the surgeon should consider creating a notch to accommodate the stapedial tendon whenever it inserts high on the stapes capitulum. When the malleus is present, the surgeon should consider tapering or trimming the lateral aspect of the platform anteriorly to permit positioning of the prosthesis next to the malleus handle, as depicted in Figure 4. When the malleus is absent, the platform may retain a flat top, as illustrated in Figure 5. The surgeon can attain added stabilization by creating contact between the prosthesis platform and the posterior bony annulus. When this is undertaken, the platform should be thinned at the site of contact to the bony annulus to minimize the formation of dense adhesions. The prosthesis should make approximately 0.5 mm of contact to the bony annulus. Sound conduction continues to work because of the flexibility of the cartilage. Ultimately, a thin fibrous sheath envelops the cartilage POW. This sheath secures the attachment of the prosthesis to the stapes capitulum. Cartilage PORPs demonstrate the following advantages: Nonmedical personnel process the donor tissue. The cartilage POW blanks can be stored in a tissue bank for long periods of time in sterile condition. Storage in the operating room makes them immediately available to the surgeon, saving the patient unnecessary anesthesia time. The cartilage POW blanks are easily sculpted into custom sizes and shapes for individual ears.
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Figure 4. When the malleus is present, the anterior most portion of the platform is tapered and trimmed to fit against the malleal handle. (From Chole RA, Hyung-jongK: Ossiculoplasty with presculptedbanked cartilage. OperativeTechniques in Otolaryngology-Head and Neck Surgery 7:38,1996; with permission.)
They are technically less demanding and faster than sculpting homograft ossicles during the surgical procedure. They consistently achieve excellent hearing results when in contact with adjacent bony walls because of the inherent cartilage flexibility. They benefit from Shea’s design to facilitate proper placement without risk of extrusion. The hearing results are stable over time unless severe infection or recurrent cholesteatoma is present. For the hearing results of cartilage prostheses compared with other prostheses, please refer to Table
Figure 5. When the malleus is absent, a flatter platform is used (compare with Fig. 4). (From Chole RA, Hyung-jongK: Ossiculoplasty with presculptedbankedcartilage. OperativeTechniques in Otolaryngology-Head and Neck Surgery 7:38,1996; with permission.)
MIDDLE EAR RECONSTRUCTIVE TECHNIQUES
497
ABSENTINCUSANDSTAPESSUPRASTRUCTURE
Wide Oval Window Niche, Presculpted Cartilage Total Ossicular Replacement Prosthesis
When the incus and the stapes superstructure are absent, a total ossicular reconstruction must be undertaken. The surgeon should first assess the dimensions of the oval window niche before selecting a reconstructive approach. When a wide niche is present, the authors recommend using a cartilage total ossicular replacement prosthesis (TORPh6The surgeon undertakes measurements from the stapes footplate to the tympanic membrane and adds 0.5 mm. The cartilage blank is customized to that length. The same cartilage blank used for POW reconstruction is also used for TORP reconstruction. The shaft of the cartilage blank is then tapered to fit into the oval window niche, as demonstrated in Figure 6. The surgeon should be careful to avoid excessive thinning of the shaft because the prosthesis may lose structural integrity. The surgeon can modify the platform of the cartilage prosthesis to engage the malleus, to contact with the bony annulus, or to interface with the tympanic membrane without a malleus following the guidelines noted in the previous section. The cartilage TOW is not recommended when the oval window niche is narrow. Three reasons limit the use of the cartilage TORP in this scenario. First, the surgeon may not be able to adequately taper the shaft without losing structural integrity of the prosthesis. Second, fixation of the prostheses can occur if the shaft contacts the walls of the niche, as shown in Figure 7. Third, the surgeon’s view of the footplate may be completely obstructed by the platform of the prosthesis. Narrow Oval Window Niche, Goldenberg Total Ossicular Replacement Prosthesis
When the incus and stapes are absent and the oval window niche is narrow, the authors recommend using a composite prosthesis, such as Goldenberg’s flex-
Figure 6. When the banked cartilage is used in the total ossicular replacement prosthesis (TORP) configuration, the shaft of the prosthesis is tapered to fit into the oval window niche. (From Chole RA, Hyung-jongK: Ossiculoplastywith presculptedbanked cartilage.Operative Techniques in Otolaryngology-Head and Neck Surgery 7:38,1996; with permission.)
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Figure 7. When the oval window niche is very narrow, placement of the prosthesis is sometimes blind because the platform obstructs the surgeon’s view. Furthermore, adhesions may form between the walls of the niche and the shaft of the implant, thus impairingmobility. (From Chole RA, Hyung-jong K: Ossiculoplasty with presculpted banked cartilage. Operative Techniques in Otolaryngology-Head and Neck Surgery 7:38,1996; with permission)
ible hydroxyapatite prosthesis.’O The head of these prostheses are hydroxyapatite and designed with either a hook to accommodate the malleus when present or a flat elliptical design to interface directly with the tympanic membrane when the malleus is absent or too anteriorly positioned for use. The shaft is wire reinforced to add strength to the narrow profile. The surgical technique begins with measuring the distance from the tympanic membrane or the malleus to the footplate. The goal is to have slight tension between the head of the prosthesis and the tympanic membrane. The Plastiporeshaft of the incus-stapesprosthesis is trimmed to 0.5 mm longer to achieve slight tension when placed. The hydroxyapatite head is grasped with toothless forceps and a sharp blade is used to cut the shaft at a right angle. The prosthesis is then placed into the middle ear. If the malleus is present and its location relative to the oval window lends itself to incorporating it in the reconstruction, then the malleus is gently elevated and the hydroxyapatite hook is engaged, as depicted in Figure 8A. If the malleus cannot be used, the oval disk prosthesis is positioned under the tympanic membrane, as shown in Figure 8B. The shaft is placed on the stapes footplate. The amount of tension can be increased by sliding the head of the prosthesis to a position on the tympanic membrane closer to the oval window or decreased by positioning the prosthesis in more lateral regions of the tympanic membrane. The tympanic membrane can be repositioned to evaluate the final positioning of the prosthesis, and the round window reflex can be assessed. The authors prefer to add a thin tragal cartilage platform between the tympanic membrane and the hydroxyapatite head of the prosthesis to further decrease the possibility of extrusion. The middle ear space is packed with gelatin sponge to ensure stabilization. The primary advantage of the composite prosthesis is the ability to obtain a narrow prosthesis with sufficient structural integrity. The hydroxyapatite portion of the prosthesis is more biocompatible, and the shaft is easily customized in patients with a narrow oval window niche. Please refer to Table 2 for hydroxyapatite-PIastipore composite prosthesis hearing
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499
Figure 8. A, Positioning the incus-stapes prosthesis when the malleus is present. B, Positioning the incus-stapes prosthesis when the malleus is absent. (From Goldenberg RA: Ossiculoplastywith composite prostheses, PORP and TORP. OtolaryngolClin NorthAm 27:727, 1994; with permission.)
ABSENT STAPES FOOTPLATE
This surgical scenario occurs in a minority of cases. The surgical approach includes harvesting a perichondrial graft from the lateralmost aspect of the tragal cartilage. In this location, the perichondrium is stiff and thickened. These properties help to prevent displacement of the graft into the vestibule. Reconstruction should use the cartilage TORP or flexible hydroxyapatite TORP, as shown in Figure 9.6 OSSICULAR RECONSTRUCTION WHEN TYMPANIC MEMBRANE IS PERFORATED
Middle ear reconstruction is often necessary in the surgical scenario of a perforated tympanic membrane. The surgeon must assess the magnitude of the tympanic membrane perforation. When it is extensive, the surgeon may decide to stage the reconstruction, repairing the tympanic membrane and eradicating the disease with the first stage and then reconstructing the ossicular chain with the second stage. In most cases, both stages are performed at the same time. When a small perforation corresponds with placement of the disk-shaped cartilage platform of the prosthesis, the perforation may be grafted with the cartilage prosthesis,as seen
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Figure 9. A total ossicular replacement prosthesis (TORP) may be placed over the perichondrial graft in the absence of a stapedial footplate. (From Chole RA, Hyung-jong K: Ossiculoplasty with presculpted banked cartilage. OperativeTechniques in Otolaryngology-Head and Neck Surgery 7:38,1996;with permission.)
in Figure 10. This surface readily re-epithelializes, and further grafting is not necessary6 When the perforation is larger than the head of the cartilage prosthesis, the tympanic membrane requires grafting. The reconstruction options include temporalis fascia, tragal perichondrium, and tragal cartilage. MIDDLE EAR AERATION
Atelectasis of the middle ear is a challenging problem facing the surgeon. During middle ear surgery, the primary objective is eradication of disease. If the mucosa can be salvaged without risk for leaving residual disease, then this helps to minimize the possibility of the tympanic membrane scarring to bare bone. If the mucosa suffers only minimal damage, then middle ear packing material can provide a temporary barrier to adhesion of tympanic membrane to traumatized mucosa. When mucosa is removed during eradication of disease then packing material is essential. Common packing material includes gelatin sponge, silicone sheeting, and Gelfilm; each of these has advantages and disadvantages. Gelatin Sponge
Gelatin sponge (Gelfoam [Pharmacia and Upjohn, Bridgewater, NJ] purified pork-skin gelatin granules) is widely used to support middle ear surgery, but some studies question possible side effects. Animal studies suggest that Gelfoam may predispose to the formation of connective tissue, bone formation, and fibrosis.9,16,19,26 In some human studies, Gelfoam has been noted to predispose to granulation whereas in other studies, Gelfoam has been found to decrease the chance of developing granulation tissue.s
MIDDLE EAR RECONSTRUCTIVE TECHNIQUES
501
:---
Implant may be used to graft a perforation Contact with annulus stabilizes implant but does not adversely
Implant may be trimmed
Figure 10. When there is a perforation in the tympanic membranethat correspondswith the placement of the prosthesis head then the platform of the prosthesis may serve as a graft for the perforation. (From Chole R A Ossiculoplasty with presculpted banked cartilage. Otolaryngol Clin North Am 27:717, 1994; with permission)
Silicone
Silicone (Silastic,Xomed-Treace, Jacksonville,FL)sheeting is a permanent and well-tolerated middle ear implant. Thin Silastic sheeting (0.013 mm) implanted into the middle ear prevents adhesion of the tympanic membrane graft to the promontory of the middle ear. Gelatin Sheeting
Gelatin sheeting (Gelfilm, Pharmacia and Upjohn, Bridgewater, NJ) is the same material as Gelfoam in a different structure. Gelfilm is constructed as a thin, transparent sheet. The use of Gelfilm is advised when extensive loss of mucosa has occurred. Some advantages of Gelfilm include: It avoids staged operations permitting eradication of disease and tympanoplasty in one stage. It is believed to promote mucosal healing before reabsorption.Reabsorption takes from 1 to 6 months in humans, depending on the size of Gelfilm and nature of the middle ear tissue. It decreases incidence of primary and late perforation. Although Silastic is well tolerated in the middle ear, it may extrude. It decreases the incidence of an immobile, retracted tympanic membrane adhering to the promontory. A comparison of absorbable gelatin sponge (Gelfoam), absorbable gelatin sheet (Gelfilm),and absorbable collagen sheet (Instat, Johnson and Johnson, Arlington, TX) reached the following conclusions. Gelfoam promotes fibrosis at a
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higher rate than control in the rat model, whereas Gelfilm and Instat do not promote fibrosis at a higher rate than normal. The suggested mechanism of fibrosis was Gelfoam serving as a scaffold for fibroblast growth between the promontory and the tympanic membrane or ossicular chain. The authors recommend the use of Gelfilm or Silastic sheeting when significant denuding of the mucosa has occurred, as depicted in Figure 3.
SUMMARY Middle ear reconstructive techniques have increased to such an extent that the otolaryngologist is faced with a bewildering number of surgical options. The literature has yet to demonstrate any technique to be optimal in every surgical scenario because of a lack of direct comparisons between techniques and dissimilar criteria for measuring success. This article uses hearing results and the ability to resist extrusion as the principal measures of success. This article provided middle ear reconstructive techniques proven to be successful for commonly faced surgical dilemmas.
References 1. Applebaum WL An hydroxylapatite prosthesis for defects of the incus long process. Laryngoscope 103:330,1993 2. Austin D F Ossicular reconstruction. Arch Otol9425, 1971 3. Brackmann DE, SheehyJL, Luxford WM: TORPs and POWs in tympanoplasty:Areview of 1042 operations. Otolaryngol Head Neck Surg 92:32,1984 4. Brackmann DE, Sheehy JL: Tympanoplasty TOWS and PORPs. Laryngoscope 89:108, 1979 5. Chole RA: Ossicular replacement with self-stabilizing presculptured homologous cartilage. Arch Otolaryngol 108:560, 1982 6. Chole RA: Ossiculoplasty with presculpted banked cartilage. Otolaryngol Clin North Am 27717,1994 7. Chole RA: Use of presculpted, banked cartilage transplants in ossicular reconstruction. Arch Otolaryngol Head Neck Surg 113:145,1987 8. Falbe-Hansen J, Tos M Silastic and gelatin film sheeting in tympanoplasty. Ann Otol Rhinol Laryngol84:315, 1975 9. Gjuric M: Aborbable gelatin sponge (marbagelan)in otosurgery: An experimentalstudy in the guinea pig. Laryngol Rhinol Otol66:186,1987 10. Goldenberg RA: Ossiculoplasty with composite prostheses, PORP and TOW. Otolaryngol Clin North Am 27727,1994 11. Gotay-Rodriguez VM, Schuknecht H F Experienceswith type IV tympanoplasty.Laryngoscope 87522,1977 12. Grote JJ: Reconstruction of the middle ear with hydroxylapatite implants: Long-term results. Ann Otol Rhinol Laryngol99:12, 1990 13. Guilford FR:Repositioning of the incus. Laryngoscope, 75:236,1965 14. Hall A, Rytzner C: Stapedectomyand autotransplantation of ossicles.Acta Otolaryngol (Stockh)47318,1957 15. Hall A, Rytzner C: Vitality of autotransplanted ossicles. Acta OtolaryngolSuppl (Stockh) 158335,1960 16. Hellstrom S, Salen B, Stenfors L: Absorbable gelatin sponge (gelfoam)in otosurgery:One cause of undesirable postoperative results? Acta Otolaryngol (Stockh)96:269, 1983 17. Hentrich RL, Graves GA, Stein HG, et a1 An evaluation of inert and resorbable ceramics for the future. J Biomed Mater Res 5:25, 1971 18. Hough J: Incudostapedial joint separation: Etiology, treatment and significances.Laryngoscope 69:644,1959
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19. Joseph R The effect of absorbable gelatin sponge preparations and other agents on scar formation in the dog's middle ear. Laryngoscope 72:1528,1962 20. Menvin G: Bioglass middle ear prosthesis: preliminary report. Ann Otol Rhinol Laryngol 95:78, 1986 21. Monsell EM: Results and outcomes in ossiculoplasty. Otolaryngol Clin North Am 27835, 1994 22. Ogawa S, Satoh I, Tanaka H: Patulous eustachian tube: A new treatment with insertion of aborbable gelatin sponge solution. Arch Otolaryngol Head Neck Surg 102:276,1976 23. Pauler M, Plenck H: Macor ceramics in soft and hard tissue. In Grote JJ (ed): Biomaterials in Otology. Boston, The Hague, Martinus Nijhoff Publishers, 1984, p 74 24. Plester D, Jahnke K Ceramic implants in otologic surgery. Am J Otol3:104, 1981 25. Reek R, Helms J: The bioactive glass ceramic cervital in ear surgery, five years' experience. Am J Otol6:280, 1985 26. Ribari 0, Jori J, Tomity J: Clinical and experimental studies on the incorporation of materials applied as covering for the labyrinth window. Acta Otolaryngol (Stockh) 89:384, 1980 27. Shea JJ, Emmett J R Biocompatible ossicular implants. Arch Otolaryngol104:191, 1978 28. Shea JJ: Fenestration of the oval window. Ann Otol Rhinol Laryngol67932,1958 29. Shea JJ: Plastipore total ossicular replacement prosthesis. Laryngoscope 86239,1976 30. Silverstein H, McDaniel AB, Lichtenstein R: A comparison of POW, TORE', and incus homograft for ossicular reconstruction in chronic ear surgery. Laryngoscope 96(2):159, 1986 31. Smyth GDL, Hassard TH, Kerr AG, et a1 Ossicular replacement prosthesis. Arch Otolaryngol 104:345, 1978 32. Van Blitterswijk CA, Grote JJ: Biocompatibility of clinically applied hydroxylapatite ceramic. Ann Otol Rhinol Laryngol, 99:12, 1990 33. Wiillstein H. Theory and practice of tympanoplasty. Laryngoscope 66:1076,1956
Address reprint requests to Richard A. Chole, MD, PhD Department of Otolaryngology-Head and Neck Surgery Washington University School of Medicine 517 South Euclid Avenue, Box 8115 St. Louis, MO 63110