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Ossicular chain reconstruction
OSSICULAR CHAIN RECONSTRUCTION JOHN R. EMMETT, MD
The historical aspects surrounding the development of osslcular implants are reviewed. The currently available biocompatible implant materials are described, and their frequency of use by otologic surgeons in the reconstruction of the sound-conducting mechanism summarized. The author outlines his personal techniques for the successful use of biocompatible osslcular implants.
Reconstruction of the drum and the sound-conducting mechanism of the middle ear is the contribution of tympanoplasty to the original efforts to eradicate infection in the surgical t r e a t m e n t of c h r o n i c otitis media. 1"2 Numerous combinations of the graft position, 3 ossicular interposition, 4's cartilage 6'7 and bone struts, sq° and various types of solid plastics and metal 11-19 have been used. Each technique is plagued with its own particular problems, including graft failures, implant extrusions, and persistent and recurrent conductive hearing loss. 3-25 There are two schools of thought among otologists with regard to reconstruction of the sound-conducting mechanism of the middle ear. One group believes the middle ear should not be violated by nonliving material and that only human autograft or homograft material--usually bone or cartilage--should be used in reconstructing the sound-conducting mechanism of the middle ear. The other group seeks to use the new biocompatible implant materials, developed in recent years by material scientists, to reconstruct this mechanism. They argue that these materials, the most inert ever developed, are less foreign than nasal, knee, or tragal cartilage, or bone taken from the same (or another) person and stored in a variety of solutions for varying lengths of time under various conditions before being used as implant material.
HISTORY The use of plastic and metallic implants in otolaryngologic and maxillofacial surgery has a long history. In one of his first reports on tympanoplasty (1956), Wullstein 2 reported the use of an oval strut of vinyl-acrylic "palavit" that acted as an acoustic transmitter between the mobile footplate and the tympanic membrane graft in his type-four operation. Poor results with this material quickly caused him to abandon its use. Shea 26'27 was the first to use a length of polyethylene 90 tubing to reconstruct the sound-conducting mechanism of the middle ear in a tympanoplasty. He was also the first to introduce the idea of the underlay vein graft From the Department of Otolaryngology-Head and Neck Surgery, University of Tennessee, Memphis, TN, and the Department of Otolaryngology-Head and Neck Surgery, University of North Carolina, Chapel Hill, NC. Address reprint requests to John R Emmett, MD, Shea Chmc, 6133 Poplar Pike at Ridgeway, Memphis, TN 38119 Copyright © 1995 by W B Saunders Company
1043-1810/95/0601-0005505.00/0 22
(1957). Later, Teflon (Dow Corning Corp, Midland, MI) tubing and a hollow umbrella-like columella were used by Austin (1962)2s and other surgeons 16-1s (Fig 1). Palva et a114A5reported using metallic implants in the treatment of chronic otitis media. Results with these solid plastic and metallic implants were so poor--because of migration, extrusion, and penetration into the inner ear--that by the time of the Fourth Shambaugh-Shea Workshop on Middle-Ear Surgery in 1971, there was general agreement that these solid plastic and metallic implants had no place in the surgical treatment of chronic otitis media. In recent years, collaborative efforts among material scientists and oral, orthopedic, plastic, and otolaryngologic surgeons have elucidated biological and functional criteria for implant material. 29"31 Their criteria have guided the development of a new class of materials, specifically designed for implantation.
PLASTIPORE One such material, a high-density polyethylene sponge (HDPS), has nonreactive properties, with sufficient porosity to encourage tissue ingrowth. High-density polyethylene sponge is one of the most nonreactive materials known w h e n tested in simulated biochemical exposure to pseudoextracellular fluid. 32"33 Microscopic examination of sections of HDPS, removed after many months in the middle ears of human patients, shows that they are invaded by an interlacing network of fibrous connective tissue. An occasional multinucleated giant cell is seen around the implant, and some investigators have attempted to attach importance to its presence. 34 However, foreign body rejection of an implanted plastic material has never been shown to be related to the number of giant cells present. 35"36 This is consistent with reported results of tests in vitro. Two basic types of prostheses are commercially available. One is the drum-to-footplate total ossicular replacement prosthesis (TORP), used w h e n the stapes superstructure is missing (Fig 2). The other is the drumto-stapes partial ossicular r e p l a c e m e n t prosthesis (PORP), the hollow center of which fits over the head of the stapes (Fig 3). Shea and Emmett 37 first reported on the successful restoration of hearing using Plastipore TORP and PORP (Richards Medical Company, Inc, Memphis, TN) in a large series of patients. Since that time, similar success in large series has been reported by Hicks et al, 38 Brackmann and Sheehy, 39 and Silverstein et al. 4°
OPERATIVE TECHNIQUES IN OTOLARYNGOLOGY--HEAD AND NECK SURGERY, VOL 6, NO 1 (MAR), 1995. PP 22-26
permits coupling with other materials (such as stainless steel), thus lending itself to a wide variety of prosthetic designs. The basic TORP design is referred to as "total," and the PORP design, as "partial." The present author has reported on his long-term success using these prostheses .41
CERAVITAL The HDPS prosthesis, while not totally inert, can be described as minimally reactive. It achieves stabilization by mechanical bonds resulting from the ingrowth of fibrous connective tissue into its porous structure. In 1971, Hench et a142 introduced a new glass-ceramic material that, w h e n implanted, became bioactive and developed an apatite-rich gel layer that resulted in both collagen and bone mineral deposition. This material was stabilized in the host tissue by direct chemical bonding, as opposed to the mechanical bonding in the minimally reactive HDPS prosthesis. Hench's glass-ceramic was modified by Bromer et al, 43 and this bioactive glassceramic material is available under the trade name Ceravital (Xomed-Treace). The successful use of Ceravital, both as ossicular replacement prosthesis and canal wall replacement prosthesis, has been reported. 44-47 FIGURE 1. Early ossicular prostheses. From top. Smyth malleus-to-stapes crura (clothespin) prosthesis, Shea malleus-to-footplate prosthesis, Austin drum-to-footplate (umbrella) prosthesis
POLYCEL A more recent and versatile manufacturing process is used to create thermalfused HDPS known as Polycel (Xomed-Treace, Jacksonville, FL). This latter process
BIOGLASS MIDDLE EAR PROSTHESIS Bloglass (American Blomaterials Corp, Princeton, NJ) is a bioactive, transparent glass developed by Hench. 42 Although differing chemically from Ceravital, it has similar properhes of implant-host reactivity resulting m the formahon of a chemical bond with hving tissue. Mer-
FIGURE 2. Drumto-footplate total osslcular replacement prosthesis (TORP). EMMETT
23
FIGURE 3. Drumto-footplate partml ossicular replacement prosthesis (PORP).
win 48 has reported on the successful use of the Bioglass middle ear prostheses.
HYDROXYAPATITE Hydroxyapatite (Xomed-Treace), which is calcium phosphate in the sintered form, is the main constituent of the mineral matrix of bone. Hydroxyapatite ceramic can be made into a porous and a dense form. Grote 49 has shown good ingrowth of living bone tissue into porous hydroxyapatite. He has also shown that the dense form acts as a stable bioactive ceramic with good tissue acceptance formin~ an adequate epithelial layer on the implant. Grote-5° reported on the successful use of hydroxyapatite in ossicular chain and canal wall reconstruction.
PROPLAST Proplast (Vitek, Inc, Houston, TX) is a minimally reactive material that is a composite of linear homopolymers of tetrafluoroethylene (PTFE) and graphite fiber. Proplast has a very high percent porosity and pore size. Fibrous tissue as well as bone ingrowth has been shown by Homsy. 51 There have been numerous reports of the use of Proplast in otologic surgery. 52-54 However, Grote, 5° one of the earlier investigators using Proplast, reported that after longer postoperative periods a marked giantcell reaction and hyalinization in the pores of the implants were noted.
OSSlCLE CUP AND COLUMELLA PROSTHESIS The Schuring Ossicle Cup Prosthesis (Smith Nephew and Richards, Memphis, TN) bridges the gap between the use of autograft and homograft bone and biocompatible ira-
24
plant materials. It consists of a Teflon cup, the shaft of which fits into a hole drilled into an autograft or homograft incus or malleus head. The cup is placed on the stapes capitulum and the ossicle under the d r u m or graft. Similarly, the columella prosthesis consists of a Teflon shaft that is fitted into a hole drilled into the incus or malleus head. The base of the shaft is placed onto the footplate and the ossicle medial to the d r u m or graft. The long-term success of these implants has been reported by Schuring. 55
IMPLANT SURVEY The biocompatible ossicular implants reviewed are commercially available to the otolaryngologic community. An investigative surgeon's repeated use of a particular ossicular implant type, during the implant's developmental stage, will often result in a refined surgical technique that insures success of the implant. However, the true test of the success of a particular implant is reflected through its general acceptance and use in the otolaryngologic community. Factors crucial to the acceptance of a prosthesis would include long-term restoration of hearing, ease of use, and cost. In an attempt to determine which of the commercially available biocompatible implants were being used and found to be satisfactory, the experiences of the American Otological Society and the American Neurotology Society were surveyed, and the results of this survey have been reported. 56 The most frequently used material in reconstructing the sound-conducting m e c h a n i s m was autograft or homograft ossicles, followed by cartilage and Plastipore TORP and PORP. Of the biocompatible implants, the most frequently used were Plastipore TORP and PORP, followed, second, by the Polycel total and partial and, third, by the bioglass prosthesis. Of the bio-
OSSICULAR CHAIN RECONSTRUCTION
compatible i m p l a n t s used, three i m p l a n t s w e r e f o u n d to be m o r e satisfactory b y the r e s p o n d i n g s u r g e o n s . Nineteen of the s u r g e o n s r e s p o n d i n g h a d u s e d the Schuring ossicle cup a n d columnella, a n d 100% of t h e m f o u n d it satisfactory. N i n e t y - e i g h t p e r c e n t of the 51 s u r g e o n s w h o h a d u s e d the Polycel total a n d partial p r o s t h e s e s f o u n d t h e m satisfactory. Eighty-six p e r c e n t of the 14 s u r g e o n s w h o h a d u s e d the H y d r o x y a p a t i t e p r o s t h e s i s f o u n d it satisfactory. It w a s interesting that e v e n t h o u g h the m o s t c o m m o n l y u s e d reconstructive material r e p o r t e d w a s autograft a n d h o m o g r a f t b o n e a n d cartilage, a n u m b e r of the s u r g e o n s i n d i c a t e d t h a t t h e y w e r e a b a n d o n i n g the u s e of hom o g r a f t materials b e c a u s e of the possibility of the s p r e a d of the acquired i m m u n o d e f i c i e n c y s y n d r o m e (AIDS) virus. Because of this possibility, the general use of biocompatible i m p l a n t s will u n d o u b t e d l y increase in the future. In the 5 y e a r s since the a b o v e - m e n t i o n e d s u r v e y w a s r e p o r t e d ossicular i m p l a n t s m a d e of h y d r o x y a p a t i t e h a v e gained considerable a c c e p t a n c e .57,58 O n e o f the m a i n a d v a n t a g e s of this material is that it is well tolerated in the middle ear. Interposition of cartilage or other tissues b e t w e e n the h e a d of the p r o s t h e s i s a n d the t y m p a n i c m e m b r a n e are not necessary.
PERSONAL TECHNIQUE In a review of m y p e r s o n a l l o n g - t e r m results u s i n g prostheses m a d e of Polycel, two c o m p h c a t i o n s occurred m o r e c o m m o n l y : p r o s t h e s i s extrusion, a n d persistent a n d recurrent conductive h e a r i n g loss. 41 Several points of t e c h m q u e m a y help p r e v e n t extrusion. If the prosthesis :s too long a n d slightly elevates the graft, p r e s s u r e necrosis of the t y m p a n i c m e m b r a n e and/or graft will occur with e x p o s u r e and/or extrusion of the prosthesis. A n a t t e m p t should be m a d e to place a portion of the p r o s t h e s i s medial to the h a n d l e of the malleus. This not only helps p r e v e n t extrusion but also aids m a c h i e v i n g m a x i m a l h e a r i n g gain. P r o s t h e s i s p l a c e m e n t medial to the chorda t y m p a n i n e r v e also helps secure the p r o s t h e s i s in place. A review of m y longt e r m results w i t h Polycel a n d Plastipore ossicular prostheses points out the necessity of u s i n g a tissue interface, usually cartilage, b e t w e e n the h e a d of the p r o s t h e s i s a n d the t y m p a n i c m e m b r a n e graft to h e l p p r e v e n t prosthesis extrusion. As m e n t i o n e d , this tissue interface is not necessary w h e n u s i n g p r o s t h e s e s m a d e of h y d r o x y l a p a tite. The s a m e fibrous tissue connections that eventually fix the prosthesis to the footplate or s t a p e s - - a n d to the undersurface of the t y m p a n i c m e m b r a n e - - c a n also fix the prosthesis to the p r o m o n t o r y , Fallopian canal, a n d scutum. At p l a c e m e n t , care m u s t be t a k e n to isolate the prosthesis f r o m these b o n y structures w i t h small pieces of absorbable gelatin s p o n g e or siliconized r u b b e r sheeting. If p r e s s e d G e l f o a m (Upjohn, K a l a m a z o o , MI) is used, allowance m u s t be m a d e for its e x p a n s i o n as it b e c o m e s moist. If such allowance is not m a d e , as the Gelfoam e x p a n d s a n d p r e s s e s against the u n d e r s u r f a c e of the h e a d of the prosthesis, the p r o s t h e s i s will be lifted f r o m the stapes footplate or f r o m the h e a d of the stapes. If the prosthesis ts too short a n d not in g o o d contact with the t y m p a n i c m e m b r a n e , c o n d u c t i v e h e a r i n g loss will persist.
EMMETT
CONCLUSION O v e r the last decade, as n e w i m p l a n t materials h a v e bec o m e available a n d surgical t e c h n i q u e s h a v e b e e n refined, the general use a n d acceptance of these i m p l a n t s has grown. W h e n w e , as otologists, look at the extraordinary p r o g r e s s that h a s b e e n m a d e in the u s e of b i o c o m patible i m p l a n t s in cardiovascular, orthopedic, a n d o p h thalmologic surgery, o u r first steps in their u s e in the middle ear s e e m v e r y small b y c o m p a r i s o n .
REFERENCES 1. Zollner I Pnnclples of plashc surgery of sound conducting apparatus J Laryngol Otol 69.637-652, 1955 2. Wullstem H. Theory of practlc of tympanoplasty. Laryngoscope 66" 1076-1093, 1956 3. Sheehy JL. Oss:cular problems m tympanoplasty Arch Otolaryngol 81.115-122, 1965 4. House WF, Patterson ME, Lmth:cum FH: Incus homografts m chronic ear surgery Arch Otolaryngol 84 148-153, 1966 5. Pulec JL, Sheehy JL. Tympanoplasty Osslcular chain reconstruchon Laryngoscope 83.448-465, 1973 6. Jansen C. Carhlage tympanoplasty Laryngoscope 73:1288-1302, 1963 7. Goodhlll V. Tragal penchondrmm and cartilage m tympanoplasty. Arch Otolaryngol 85 480-491, 1973 8. Bauer M. Bone autograft for oss:cular reconstruct-ton. Arch Otolaryngol 83'335-338, 1966 9. Austin DF Osslcular reconstruchon Otolaryngol Chn North Am 5 145-160, 1972 10. Austin DF Osslcular reconstruchon Arch Otolaryngol 94 525-535, 1971 11. Sheehy JL Plastic sheeting in tympanoplasty Laryngoscope 83 1140-1159, 1973 12. House WF, Sheehy JL Functional restoration m tympanoplasty Arch Otolaryngol 78 98-101, 1963 13. Waltner JG Dumbbell tympanoplasty Arch Otolaryngol 83 339342, 1966 14. Palva A, Karla J Results with two- or three-legged wire columelhzation in chronic ear surgery Ann Otol Rhlnol Laryngol 80 760-765, 1971 15. Palva T, Palva A, Kar)a J Ossicular reconstruct:on in chromc ear surgery Arch Otolaryngol 98 340-348, 1973 16. House HP Polyethylene in middle ear surgery Arch Otolaryngol 71 926-931, 1960 17. Harnson WH, Shambaugh GE, Kaplan J, et al Prosthes:s m the middle ear Arch Otolaryngol 69 661-666, 1959 18. Hayden GD Results w:th polyethylene T-strut m the restorahon of hearing Laryngoscope 71 5054-5061, 1961 19. Plester D Problems m tympanoplasty Laryngol Otol 75 879-884, 1961 20. Jansen C Methods of oss~cular reconstruchon Otolaryngol Chn North Am 5 97-109, 1972 21. Smyth DGL Tympamc reconstruchon Otolaryngol Chn North Am 5 111-125, 1972 22. Garcla-Ibanez L Sonomvers:on m obhterahve otoscleroms Arch Otolaryngol 82 340-345, 1965 23. S:edentop KH, Brown RC Type III polyethylene columella tympanoplasty Arch Otolaryngol 83 560-565, 1966 24. Wolferman A Reconstruchve Surgery of the Middle Ear New York, NY, Grune & Stratton, 1970, pp 143-145 25. Harrison WH Osslcular reconstruct:on Arch Otolaryngol 96 525535, 1969 26. Shea JJ Tympanoplasty m chromc nght ot:t:s media. A case report Memphis Med 33 271-275, 1958 27. Shea JJ Veto graft closure o1 eardrum perforahons Northwest Med 59 770-772, 1960 28. Austin DF Veto graft tympanoplasty Two-year report Otolaryngol Head Neck Surg 67 198-208, 1963
25
29. Homsy CA, Cam TC, Kessler B, et al. Porous implant systems for prosthesis stabdlzatlon. Chn Orthop 89.220-235, 1972 30. Homsy CA. Implant stablhzation. Chemical and blochermcal conslderation Orthop Chn North Am 4:295-311, 1974 31. Homsy CA, Kent JA, Hinds EL. Materials for oral implantation. Biological and functional crstena J Am Dent Assoc 86:817-832, 1973 32. Shea JJ, Homsy CA: The use of proplast m otologlc surgery. Laryngoscope 84.1835-1845, 1974 33. Shea JJ, Emmett JR, Smyth GDL. Blocompatible implants m otology. ORL J Otorhinolaryngol Relat Spec 39 9-15, 1977 34. Frederickson J, Kerr A, Brackmann D, et al' Symposium on prosthetic materials m middle ear surgery. Presented at the Amencan Otological Society, Msami Beach, FL, May 26, 1985 35. Harrison JH, Swanson DS, Lincoln AF' A comparison of the t~ssue reaction to plastic materials Arch Surg 82:138-144, 1956 36. Mulhson EG Silicones in head and neck surgery. Arch Otolaryngol 104:191-196, 1978 37. Shea JJ, Emmett JR. Blocompatlble ossicular Implants. Arch Otolaryngol 104:191-196, 1978 38. Hicks GW, Wright JW Jr, Wright III JW, et al Use of Plastlpore for oss~cular chain reconstructaon An evaluataon Laryngoscope 88 1024-1033, 1978 39. Brackmann DE, Sheehy JL. Tympanoplasty: TORPs and PORPs Laryngoscope 89.108, 1979 40. Silversteln H, McDaniel AB, Llchtenstein R. A comparison of PORP, TORP, and mcus homograft for ossicular reconstruction m chronic ear surgery. Presented at the Tnologlcal Society, Mmini Beach, FL, May 25, 1985 41. Emmett JR, Shea JJ, Moretz WH Long-term experience with biocompatible OSSlCUlarimplants Otolaryngol Head Neck Surg 94.611616, 1986 42. Hench L, Sphnter R, Allen W, et al Bonding mechanisms at the mterface of ceramic prostheslc matermls J Blomet Mater Res 2.117141, 1971 43. Bromer H, Kas H, Pfiel E Glaskermische material mlt apatlt-
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44. 45. 46. 47. 48. 49.
50.
51. 52.
53. 54. 55.
56. 57. 58.
knstallphase, msbesondere zur verwendung fur prosthetlsche zweche, sowle vertahren au seiner herstellung Patentschnft Nr 2326100, 1976 Reck R Tissue reachons to glass ceramics in the middle ear. Chn Otolaryngol 6.63-65, 1981 Reck R Bioactsve glass ceramic A new matenal m tympanoplasty Laryngoscope 93:196-199, 1983 Reck R Bloachve glass-ceramics in ear surgery. Animal studies and clinical results Laryngoscope 94:1-54, 1984 (Suppl 33) Reck R, Helms S: The bloactlve glass ceramic ceravltal in ear surgery. Am J Otol 6:280-283, 1985 Merwln G. Bloglass middle ear prosthesis. Prehmmary report. Ann Otol Rhlnol Laryngol 95'78-82, 1986 Grote J, Blltterswyjk C, Kuilpers W' Reconstruction of the middle ear with hydroxyapatlte implants. Ann Otol Rhmol Larygnol Suppl 123'95, 1986 Grote J Tympanoplasty with calcmm phosphate. Arch Otolaryngol 110:197-199, 1984 Homsy C Biocompatlbshty in selection of materials for implantation J Blomed Mater Res 4 341-356, 1970 Janeke J, Shea J Self-stablhzmg total OSSlCUlarreplacement prostheses in tympanoplasty Laryngoscope 85 1550-1556, 1975 Mlschke R, Shea J' The use of Proplast in the middle ear and oval window. Arch Otol 103.489-492, 1977 Kmjpers W, Grote J. The use of Proplast In experimental middle ear surgery Clin Otol 2:5-15, 1977 Schurxng AG, Llppy WH Semlblologsc middle ear prostheses. Osslcle cup and OSSlClecolumnella Otolaryngol Head Neck Surg 90. 628-633, 1982 Emmett, J Blocompatible xmplants in tympanoplasty Am J Otol 10 215-219, 1989 Goldenberg R' Hydroxylapatlte ossicular replacement prosthesis: Results in 157 cases. Laryngoscope 102'1091-1096, 1992 Applebaum, E' An hydroxylapatlte prosthesis for defects of the incus long process Laryngoscope 103 330-332, 1993
OSSICULAR CHAIN RECONSTRUCTION
The historical aspects surrounding the development of osslcular implants are reviewed. The currently available biocompatible implant materials are described, and their frequency of use by otologic surgeons in the reconstruction of the sound-conducting mechanism summarized. The author outlines his personal techniques for the successful use of biocompatible osslcular implants.
Reconstruction of the drum and the sound-conducting mechanism of the middle ear is the contribution of tympanoplasty to the original efforts to eradicate infection in the surgical t r e a t m e n t of c h r o n i c otitis media. 1"2 Numerous combinations of the graft position, 3 ossicular interposition, 4's cartilage 6'7 and bone struts, sq° and various types of solid plastics and metal 11-19 have been used. Each technique is plagued with its own particular problems, including graft failures, implant extrusions, and persistent and recurrent conductive hearing loss. 3-25 There are two schools of thought among otologists with regard to reconstruction of the sound-conducting mechanism of the middle ear. One group believes the middle ear should not be violated by nonliving material and that only human autograft or homograft material--usually bone or cartilage--should be used in reconstructing the sound-conducting mechanism of the middle ear. The other group seeks to use the new biocompatible implant materials, developed in recent years by material scientists, to reconstruct this mechanism. They argue that these materials, the most inert ever developed, are less foreign than nasal, knee, or tragal cartilage, or bone taken from the same (or another) person and stored in a variety of solutions for varying lengths of time under various conditions before being used as implant material.
HISTORY The use of plastic and metallic implants in otolaryngologic and maxillofacial surgery has a long history. In one of his first reports on tympanoplasty (1956), Wullstein 2 reported the use of an oval strut of vinyl-acrylic "palavit" that acted as an acoustic transmitter between the mobile footplate and the tympanic membrane graft in his type-four operation. Poor results with this material quickly caused him to abandon its use. Shea 26'27 was the first to use a length of polyethylene 90 tubing to reconstruct the sound-conducting mechanism of the middle ear in a tympanoplasty. He was also the first to introduce the idea of the underlay vein graft From the Department of Otolaryngology-Head and Neck Surgery, University of Tennessee, Memphis, TN, and the Department of Otolaryngology-Head and Neck Surgery, University of North Carolina, Chapel Hill, NC. Address reprint requests to John R Emmett, MD, Shea Chmc, 6133 Poplar Pike at Ridgeway, Memphis, TN 38119 Copyright © 1995 by W B Saunders Company
1043-1810/95/0601-0005505.00/0 22
(1957). Later, Teflon (Dow Corning Corp, Midland, MI) tubing and a hollow umbrella-like columella were used by Austin (1962)2s and other surgeons 16-1s (Fig 1). Palva et a114A5reported using metallic implants in the treatment of chronic otitis media. Results with these solid plastic and metallic implants were so poor--because of migration, extrusion, and penetration into the inner ear--that by the time of the Fourth Shambaugh-Shea Workshop on Middle-Ear Surgery in 1971, there was general agreement that these solid plastic and metallic implants had no place in the surgical treatment of chronic otitis media. In recent years, collaborative efforts among material scientists and oral, orthopedic, plastic, and otolaryngologic surgeons have elucidated biological and functional criteria for implant material. 29"31 Their criteria have guided the development of a new class of materials, specifically designed for implantation.
PLASTIPORE One such material, a high-density polyethylene sponge (HDPS), has nonreactive properties, with sufficient porosity to encourage tissue ingrowth. High-density polyethylene sponge is one of the most nonreactive materials known w h e n tested in simulated biochemical exposure to pseudoextracellular fluid. 32"33 Microscopic examination of sections of HDPS, removed after many months in the middle ears of human patients, shows that they are invaded by an interlacing network of fibrous connective tissue. An occasional multinucleated giant cell is seen around the implant, and some investigators have attempted to attach importance to its presence. 34 However, foreign body rejection of an implanted plastic material has never been shown to be related to the number of giant cells present. 35"36 This is consistent with reported results of tests in vitro. Two basic types of prostheses are commercially available. One is the drum-to-footplate total ossicular replacement prosthesis (TORP), used w h e n the stapes superstructure is missing (Fig 2). The other is the drumto-stapes partial ossicular r e p l a c e m e n t prosthesis (PORP), the hollow center of which fits over the head of the stapes (Fig 3). Shea and Emmett 37 first reported on the successful restoration of hearing using Plastipore TORP and PORP (Richards Medical Company, Inc, Memphis, TN) in a large series of patients. Since that time, similar success in large series has been reported by Hicks et al, 38 Brackmann and Sheehy, 39 and Silverstein et al. 4°
OPERATIVE TECHNIQUES IN OTOLARYNGOLOGY--HEAD AND NECK SURGERY, VOL 6, NO 1 (MAR), 1995. PP 22-26
permits coupling with other materials (such as stainless steel), thus lending itself to a wide variety of prosthetic designs. The basic TORP design is referred to as "total," and the PORP design, as "partial." The present author has reported on his long-term success using these prostheses .41
CERAVITAL The HDPS prosthesis, while not totally inert, can be described as minimally reactive. It achieves stabilization by mechanical bonds resulting from the ingrowth of fibrous connective tissue into its porous structure. In 1971, Hench et a142 introduced a new glass-ceramic material that, w h e n implanted, became bioactive and developed an apatite-rich gel layer that resulted in both collagen and bone mineral deposition. This material was stabilized in the host tissue by direct chemical bonding, as opposed to the mechanical bonding in the minimally reactive HDPS prosthesis. Hench's glass-ceramic was modified by Bromer et al, 43 and this bioactive glassceramic material is available under the trade name Ceravital (Xomed-Treace). The successful use of Ceravital, both as ossicular replacement prosthesis and canal wall replacement prosthesis, has been reported. 44-47 FIGURE 1. Early ossicular prostheses. From top. Smyth malleus-to-stapes crura (clothespin) prosthesis, Shea malleus-to-footplate prosthesis, Austin drum-to-footplate (umbrella) prosthesis
POLYCEL A more recent and versatile manufacturing process is used to create thermalfused HDPS known as Polycel (Xomed-Treace, Jacksonville, FL). This latter process
BIOGLASS MIDDLE EAR PROSTHESIS Bloglass (American Blomaterials Corp, Princeton, NJ) is a bioactive, transparent glass developed by Hench. 42 Although differing chemically from Ceravital, it has similar properhes of implant-host reactivity resulting m the formahon of a chemical bond with hving tissue. Mer-
FIGURE 2. Drumto-footplate total osslcular replacement prosthesis (TORP). EMMETT
23
FIGURE 3. Drumto-footplate partml ossicular replacement prosthesis (PORP).
win 48 has reported on the successful use of the Bioglass middle ear prostheses.
HYDROXYAPATITE Hydroxyapatite (Xomed-Treace), which is calcium phosphate in the sintered form, is the main constituent of the mineral matrix of bone. Hydroxyapatite ceramic can be made into a porous and a dense form. Grote 49 has shown good ingrowth of living bone tissue into porous hydroxyapatite. He has also shown that the dense form acts as a stable bioactive ceramic with good tissue acceptance formin~ an adequate epithelial layer on the implant. Grote-5° reported on the successful use of hydroxyapatite in ossicular chain and canal wall reconstruction.
PROPLAST Proplast (Vitek, Inc, Houston, TX) is a minimally reactive material that is a composite of linear homopolymers of tetrafluoroethylene (PTFE) and graphite fiber. Proplast has a very high percent porosity and pore size. Fibrous tissue as well as bone ingrowth has been shown by Homsy. 51 There have been numerous reports of the use of Proplast in otologic surgery. 52-54 However, Grote, 5° one of the earlier investigators using Proplast, reported that after longer postoperative periods a marked giantcell reaction and hyalinization in the pores of the implants were noted.
OSSlCLE CUP AND COLUMELLA PROSTHESIS The Schuring Ossicle Cup Prosthesis (Smith Nephew and Richards, Memphis, TN) bridges the gap between the use of autograft and homograft bone and biocompatible ira-
24
plant materials. It consists of a Teflon cup, the shaft of which fits into a hole drilled into an autograft or homograft incus or malleus head. The cup is placed on the stapes capitulum and the ossicle under the d r u m or graft. Similarly, the columella prosthesis consists of a Teflon shaft that is fitted into a hole drilled into the incus or malleus head. The base of the shaft is placed onto the footplate and the ossicle medial to the d r u m or graft. The long-term success of these implants has been reported by Schuring. 55
IMPLANT SURVEY The biocompatible ossicular implants reviewed are commercially available to the otolaryngologic community. An investigative surgeon's repeated use of a particular ossicular implant type, during the implant's developmental stage, will often result in a refined surgical technique that insures success of the implant. However, the true test of the success of a particular implant is reflected through its general acceptance and use in the otolaryngologic community. Factors crucial to the acceptance of a prosthesis would include long-term restoration of hearing, ease of use, and cost. In an attempt to determine which of the commercially available biocompatible implants were being used and found to be satisfactory, the experiences of the American Otological Society and the American Neurotology Society were surveyed, and the results of this survey have been reported. 56 The most frequently used material in reconstructing the sound-conducting m e c h a n i s m was autograft or homograft ossicles, followed by cartilage and Plastipore TORP and PORP. Of the biocompatible implants, the most frequently used were Plastipore TORP and PORP, followed, second, by the Polycel total and partial and, third, by the bioglass prosthesis. Of the bio-
OSSICULAR CHAIN RECONSTRUCTION
compatible i m p l a n t s used, three i m p l a n t s w e r e f o u n d to be m o r e satisfactory b y the r e s p o n d i n g s u r g e o n s . Nineteen of the s u r g e o n s r e s p o n d i n g h a d u s e d the Schuring ossicle cup a n d columnella, a n d 100% of t h e m f o u n d it satisfactory. N i n e t y - e i g h t p e r c e n t of the 51 s u r g e o n s w h o h a d u s e d the Polycel total a n d partial p r o s t h e s e s f o u n d t h e m satisfactory. Eighty-six p e r c e n t of the 14 s u r g e o n s w h o h a d u s e d the H y d r o x y a p a t i t e p r o s t h e s i s f o u n d it satisfactory. It w a s interesting that e v e n t h o u g h the m o s t c o m m o n l y u s e d reconstructive material r e p o r t e d w a s autograft a n d h o m o g r a f t b o n e a n d cartilage, a n u m b e r of the s u r g e o n s i n d i c a t e d t h a t t h e y w e r e a b a n d o n i n g the u s e of hom o g r a f t materials b e c a u s e of the possibility of the s p r e a d of the acquired i m m u n o d e f i c i e n c y s y n d r o m e (AIDS) virus. Because of this possibility, the general use of biocompatible i m p l a n t s will u n d o u b t e d l y increase in the future. In the 5 y e a r s since the a b o v e - m e n t i o n e d s u r v e y w a s r e p o r t e d ossicular i m p l a n t s m a d e of h y d r o x y a p a t i t e h a v e gained considerable a c c e p t a n c e .57,58 O n e o f the m a i n a d v a n t a g e s of this material is that it is well tolerated in the middle ear. Interposition of cartilage or other tissues b e t w e e n the h e a d of the p r o s t h e s i s a n d the t y m p a n i c m e m b r a n e are not necessary.
PERSONAL TECHNIQUE In a review of m y p e r s o n a l l o n g - t e r m results u s i n g prostheses m a d e of Polycel, two c o m p h c a t i o n s occurred m o r e c o m m o n l y : p r o s t h e s i s extrusion, a n d persistent a n d recurrent conductive h e a r i n g loss. 41 Several points of t e c h m q u e m a y help p r e v e n t extrusion. If the prosthesis :s too long a n d slightly elevates the graft, p r e s s u r e necrosis of the t y m p a n i c m e m b r a n e and/or graft will occur with e x p o s u r e and/or extrusion of the prosthesis. A n a t t e m p t should be m a d e to place a portion of the p r o s t h e s i s medial to the h a n d l e of the malleus. This not only helps p r e v e n t extrusion but also aids m a c h i e v i n g m a x i m a l h e a r i n g gain. P r o s t h e s i s p l a c e m e n t medial to the chorda t y m p a n i n e r v e also helps secure the p r o s t h e s i s in place. A review of m y longt e r m results w i t h Polycel a n d Plastipore ossicular prostheses points out the necessity of u s i n g a tissue interface, usually cartilage, b e t w e e n the h e a d of the p r o s t h e s i s a n d the t y m p a n i c m e m b r a n e graft to h e l p p r e v e n t prosthesis extrusion. As m e n t i o n e d , this tissue interface is not necessary w h e n u s i n g p r o s t h e s e s m a d e of h y d r o x y l a p a tite. The s a m e fibrous tissue connections that eventually fix the prosthesis to the footplate or s t a p e s - - a n d to the undersurface of the t y m p a n i c m e m b r a n e - - c a n also fix the prosthesis to the p r o m o n t o r y , Fallopian canal, a n d scutum. At p l a c e m e n t , care m u s t be t a k e n to isolate the prosthesis f r o m these b o n y structures w i t h small pieces of absorbable gelatin s p o n g e or siliconized r u b b e r sheeting. If p r e s s e d G e l f o a m (Upjohn, K a l a m a z o o , MI) is used, allowance m u s t be m a d e for its e x p a n s i o n as it b e c o m e s moist. If such allowance is not m a d e , as the Gelfoam e x p a n d s a n d p r e s s e s against the u n d e r s u r f a c e of the h e a d of the prosthesis, the p r o s t h e s i s will be lifted f r o m the stapes footplate or f r o m the h e a d of the stapes. If the prosthesis ts too short a n d not in g o o d contact with the t y m p a n i c m e m b r a n e , c o n d u c t i v e h e a r i n g loss will persist.
EMMETT
CONCLUSION O v e r the last decade, as n e w i m p l a n t materials h a v e bec o m e available a n d surgical t e c h n i q u e s h a v e b e e n refined, the general use a n d acceptance of these i m p l a n t s has grown. W h e n w e , as otologists, look at the extraordinary p r o g r e s s that h a s b e e n m a d e in the u s e of b i o c o m patible i m p l a n t s in cardiovascular, orthopedic, a n d o p h thalmologic surgery, o u r first steps in their u s e in the middle ear s e e m v e r y small b y c o m p a r i s o n .
REFERENCES 1. Zollner I Pnnclples of plashc surgery of sound conducting apparatus J Laryngol Otol 69.637-652, 1955 2. Wullstem H. Theory of practlc of tympanoplasty. Laryngoscope 66" 1076-1093, 1956 3. Sheehy JL. Oss:cular problems m tympanoplasty Arch Otolaryngol 81.115-122, 1965 4. House WF, Patterson ME, Lmth:cum FH: Incus homografts m chronic ear surgery Arch Otolaryngol 84 148-153, 1966 5. Pulec JL, Sheehy JL. Tympanoplasty Osslcular chain reconstruchon Laryngoscope 83.448-465, 1973 6. Jansen C. Carhlage tympanoplasty Laryngoscope 73:1288-1302, 1963 7. Goodhlll V. Tragal penchondrmm and cartilage m tympanoplasty. Arch Otolaryngol 85 480-491, 1973 8. Bauer M. Bone autograft for oss:cular reconstruct-ton. Arch Otolaryngol 83'335-338, 1966 9. Austin DF Osslcular reconstruchon Otolaryngol Chn North Am 5 145-160, 1972 10. Austin DF Osslcular reconstruchon Arch Otolaryngol 94 525-535, 1971 11. Sheehy JL Plastic sheeting in tympanoplasty Laryngoscope 83 1140-1159, 1973 12. House WF, Sheehy JL Functional restoration m tympanoplasty Arch Otolaryngol 78 98-101, 1963 13. Waltner JG Dumbbell tympanoplasty Arch Otolaryngol 83 339342, 1966 14. Palva A, Karla J Results with two- or three-legged wire columelhzation in chronic ear surgery Ann Otol Rhlnol Laryngol 80 760-765, 1971 15. Palva T, Palva A, Kar)a J Ossicular reconstruct:on in chromc ear surgery Arch Otolaryngol 98 340-348, 1973 16. House HP Polyethylene in middle ear surgery Arch Otolaryngol 71 926-931, 1960 17. Harnson WH, Shambaugh GE, Kaplan J, et al Prosthes:s m the middle ear Arch Otolaryngol 69 661-666, 1959 18. Hayden GD Results w:th polyethylene T-strut m the restorahon of hearing Laryngoscope 71 5054-5061, 1961 19. Plester D Problems m tympanoplasty Laryngol Otol 75 879-884, 1961 20. Jansen C Methods of oss~cular reconstruchon Otolaryngol Chn North Am 5 97-109, 1972 21. Smyth DGL Tympamc reconstruchon Otolaryngol Chn North Am 5 111-125, 1972 22. Garcla-Ibanez L Sonomvers:on m obhterahve otoscleroms Arch Otolaryngol 82 340-345, 1965 23. S:edentop KH, Brown RC Type III polyethylene columella tympanoplasty Arch Otolaryngol 83 560-565, 1966 24. Wolferman A Reconstruchve Surgery of the Middle Ear New York, NY, Grune & Stratton, 1970, pp 143-145 25. Harrison WH Osslcular reconstruct:on Arch Otolaryngol 96 525535, 1969 26. Shea JJ Tympanoplasty m chromc nght ot:t:s media. A case report Memphis Med 33 271-275, 1958 27. Shea JJ Veto graft closure o1 eardrum perforahons Northwest Med 59 770-772, 1960 28. Austin DF Veto graft tympanoplasty Two-year report Otolaryngol Head Neck Surg 67 198-208, 1963
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29. Homsy CA, Cam TC, Kessler B, et al. Porous implant systems for prosthesis stabdlzatlon. Chn Orthop 89.220-235, 1972 30. Homsy CA. Implant stablhzation. Chemical and blochermcal conslderation Orthop Chn North Am 4:295-311, 1974 31. Homsy CA, Kent JA, Hinds EL. Materials for oral implantation. Biological and functional crstena J Am Dent Assoc 86:817-832, 1973 32. Shea JJ, Homsy CA: The use of proplast m otologlc surgery. Laryngoscope 84.1835-1845, 1974 33. Shea JJ, Emmett JR, Smyth GDL. Blocompatible implants m otology. ORL J Otorhinolaryngol Relat Spec 39 9-15, 1977 34. Frederickson J, Kerr A, Brackmann D, et al' Symposium on prosthetic materials m middle ear surgery. Presented at the Amencan Otological Society, Msami Beach, FL, May 26, 1985 35. Harrison JH, Swanson DS, Lincoln AF' A comparison of the t~ssue reaction to plastic materials Arch Surg 82:138-144, 1956 36. Mulhson EG Silicones in head and neck surgery. Arch Otolaryngol 104:191-196, 1978 37. Shea JJ, Emmett JR. Blocompatlble ossicular Implants. Arch Otolaryngol 104:191-196, 1978 38. Hicks GW, Wright JW Jr, Wright III JW, et al Use of Plastlpore for oss~cular chain reconstructaon An evaluataon Laryngoscope 88 1024-1033, 1978 39. Brackmann DE, Sheehy JL. Tympanoplasty: TORPs and PORPs Laryngoscope 89.108, 1979 40. Silversteln H, McDaniel AB, Llchtenstein R. A comparison of PORP, TORP, and mcus homograft for ossicular reconstruction m chronic ear surgery. Presented at the Tnologlcal Society, Mmini Beach, FL, May 25, 1985 41. Emmett JR, Shea JJ, Moretz WH Long-term experience with biocompatible OSSlCUlarimplants Otolaryngol Head Neck Surg 94.611616, 1986 42. Hench L, Sphnter R, Allen W, et al Bonding mechanisms at the mterface of ceramic prostheslc matermls J Blomet Mater Res 2.117141, 1971 43. Bromer H, Kas H, Pfiel E Glaskermische material mlt apatlt-
26
44. 45. 46. 47. 48. 49.
50.
51. 52.
53. 54. 55.
56. 57. 58.
knstallphase, msbesondere zur verwendung fur prosthetlsche zweche, sowle vertahren au seiner herstellung Patentschnft Nr 2326100, 1976 Reck R Tissue reachons to glass ceramics in the middle ear. Chn Otolaryngol 6.63-65, 1981 Reck R Bioactsve glass ceramic A new matenal m tympanoplasty Laryngoscope 93:196-199, 1983 Reck R Bloachve glass-ceramics in ear surgery. Animal studies and clinical results Laryngoscope 94:1-54, 1984 (Suppl 33) Reck R, Helms S: The bloactlve glass ceramic ceravltal in ear surgery. Am J Otol 6:280-283, 1985 Merwln G. Bloglass middle ear prosthesis. Prehmmary report. Ann Otol Rhlnol Laryngol 95'78-82, 1986 Grote J, Blltterswyjk C, Kuilpers W' Reconstruction of the middle ear with hydroxyapatlte implants. Ann Otol Rhmol Larygnol Suppl 123'95, 1986 Grote J Tympanoplasty with calcmm phosphate. Arch Otolaryngol 110:197-199, 1984 Homsy C Biocompatlbshty in selection of materials for implantation J Blomed Mater Res 4 341-356, 1970 Janeke J, Shea J Self-stablhzmg total OSSlCUlarreplacement prostheses in tympanoplasty Laryngoscope 85 1550-1556, 1975 Mlschke R, Shea J' The use of Proplast in the middle ear and oval window. Arch Otol 103.489-492, 1977 Kmjpers W, Grote J. The use of Proplast In experimental middle ear surgery Clin Otol 2:5-15, 1977 Schurxng AG, Llppy WH Semlblologsc middle ear prostheses. Osslcle cup and OSSlClecolumnella Otolaryngol Head Neck Surg 90. 628-633, 1982 Emmett, J Blocompatible xmplants in tympanoplasty Am J Otol 10 215-219, 1989 Goldenberg R' Hydroxylapatlte ossicular replacement prosthesis: Results in 157 cases. Laryngoscope 102'1091-1096, 1992 Applebaum, E' An hydroxylapatlte prosthesis for defects of the incus long process Laryngoscope 103 330-332, 1993
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