Ossiculoplasty Treatment & Management

Hearing amplification is an alternative to ossiculoplasty in patients with conductive or mixed hearing loss.

The status of the ossicular remnants determines which implant can be used. In general, better hearing results are achieved when as much of the remaining functional ossicular chain as possible is used during reconstruction.

The weight of a prosthesis has an effect on sound conduction in the middle ear; this has been proven with standardized measurements. A weight of more than 5 mg can affect sound transmission above 1 kHz; thus, it is better to use a prosthesis that weighs less than 5 mg.

See Workup.

Alloplastic materials are the most commonly used materials for ossicular reconstruction.

Palpate whatever ossicles are present to ensure their mobility. If the malleus head is fixed, remove it to achieve a mobile malleus handle and to prevent refixation. To remove the malleus head, first remove the incus; then, section the neck of the malleus. If the stapes footplate is fixed, a stapedectomy or stapedotomy can be performed. Open the footplate only when there is an intact tympanic membrane and no evidence of active or chronic infection.

The authors recommend removal of the remaining incus and/or malleus head when cholesteatoma is in continuity with these ossicles. In this way, the risk of residual cholesteatoma is reduced because the cholesteatoma may infiltrate the bone of the ossicles. The incus body also may have scar tissue blocking the antrum.

Erosion of incudostapedial joint

Erosion of the incudostapedial joint with an intact, mobile malleus is the most common ossicular defect in children and adults. Reconstruction of this type of defect may be accomplished by several means. The first is to reconstruct the joint itself. One of the most common prostheses for joint replacement is the Applebaum incudostapedial joint prosthesis (Gyrus ENT, Bartlett, Tenn), which is made from hydroxylapatite.

This prosthesis is an elongated cube with a trough on one face to receive the residual incus long process and a hole on the opposite face for the stapes neck and capitulum as seen in the image below.

Placement is accomplished by centering the hole of the prosthesis on the stapes capitulum while lifting the long process of the incus into the trough. If the incus defect is too small to allow easy insertion of the prosthesis, use a malleus nipper or laser to slightly trim the long process of the incus. Palpate the malleus to verify good motion transmission through the prosthesis to the stapes. Supporting packing material is not necessary because the prosthesis snaps firmly into position. The Applebaum prosthesis comes in various sizes, is easy to use, and has a low extrusion rate. With time, the prosthesis may slip off the incus if the incus long process continues to erode.

Another option for joint replacement is a Kurz angular prosthesis (Plester) (Kurz Medical, Inc, Norcross, Ga) made of a gold shaft, gold cup, and titanium clips as seen in the image below.

The gold cup is placed initially on the head of the stapes. Next, the clips are crimped to the long process of the incus. One advantage of the device is that the shaft comes in various lengths to accommodate different size remnants of the long process of the incus.

A different means to reconstruct the incudostapedial joint is to bypass the stapes superstructure. This may be accomplished with a specially designed prosthesis, the Lippy-modified Robinson stainless steel prosthesis. Initially, the shaft of the prosthesis is placed on the stapes footplate between the crura, thus bypassing the stapes capitulum. The open side of the specially designed well is guided to the long process, which is lifted to enter the well under slight tension.

Supporting packing material is not necessary because the prosthesis fits snugly between the crura, which hold the prosthesis in place. If the remaining long process is too short, the tip will be too large to fit into the well of the prosthesis, and an incus replacement technique should be used (see Malleus present, stapes present). The hearing results are similar when comparing the results of either reconstruction of the incudostapedial joint with a joint prostheses or reconstruction performed through bypass of the stapes superstructure.

Polymaleinate ionomer cement (Oto-Cem, Oto-Tech, Raleigh, NC) has recently been used to bridge gaps to re-create the incudostapedial joint. ^[5] Preliminary results with this technique seem promising. ^[6]

Some authors advocate bypassing the incus remnant altogether by performing an incus replacement technique (see Malleus present, stapes present).

Malleus present, stapes present (M+S+)

In this instance, 3 options exist for reconstruction. The first option is reconstruction using an incus replacement prosthesis. A second option for reconstruction when the incus is absent and the malleus and stapes are present is to bypass the malleus. This may be accomplished using a partial ossicular reconstruction prosthesis (PORP). A third option is reconstruction using a total ossicular reconstruction prosthesis. The base of the total ossicular reconstruction prosthesis is placed on the footplate between the fallopian canal and the stapes superstructure. In theory, placement of the prosthesis in this manner may help with cradling, centering, and stabilizing the prosthesis. ^[7]

Reconstruction using a PORP is discussed in the Malleus and incus absent, stapes present section. Perform reconstruction with an incus replacement prosthesis only when the angle between the long axis of the stapes capitulum and malleus handle is less than 45° (preferably < 30°). Angles more than 45° prevent proper sound transfer between the stapes and malleus. Specifically, some sound energy is converted into an inefficient rocking motion at the footplate if the manubrium is too far anterior to the stapes.

Possible options for incus replacement prostheses include the Applebaum incus replacement prosthesis, the Wehrs single- or double-notched incus prosthesis (as seen in the image below), or the short Black Spanner Strut (as seen in the image below).

All products are from Gyrus ENT, Bartlett, Tenn. Each of these prostheses is made of hydroxylapatite except for the base of the Wehrs prosthesis, which is made of HAPEX, and the shaft of the Black Spanner Strut, which is made of fluoroplastic. HAPEX is a composite material made of 40% hydroxylapatite and 60% polyethylene by volume. By weight, HAPEX is more than 70% hydroxylapatite. Unlike hydroxylapatite, which is brittle and difficult to trim, HAPEX and fluoroplastic are trimmed easily with a scalpel.

Insertion of the Applebaum incus replacement prosthesis is performed by placing the appropriate size prosthesis on the promontory. With one hand, the malleus is elevated using a right-angle pick. With a right-angle pick in the other hand, the prosthesis is grasped under the groove that will engage the stapes. The prosthesis is brought up under the manubrium while the groove in the base of the prosthesis is lifted over the head of the stapes. Bring the prosthesis to a vertical and stable position halfway between the tip of the manubrium and the tensor tympani muscle. Moving the prosthesis closer to the tip can tighten the fit. As with all incus replacement prostheses, supporting packing material is not necessary because the prostheses snap firmly into position.

The Wehrs prosthesis insertion technique is similar to that for the Applebaum incus prosthesis. If necessary, the base of the Wehrs prosthesis can be trimmed with a scalpel. To improve the stability of the prosthesis, a notch to accommodate the stapes tendon may be fashioned in the inferior portion of the HAPEX shaft.

Placement of the short Black Spanner Strut is accomplished by trimming the fluoroplastic shaft to size, based on the distance and angle from the malleus to stapes. The hydroxylapatite head then is reattached to the trimmed shaft. The crural notches on the base of the shaft are aligned on the stapes, the malleus is lifted with a pick, and the head of the prosthesis is engaged on the mid portion of the manubrium.

When using any of the above-mentioned prostheses for incus replacement, the tensor tympani tendon may be stretched or sectioned to increase the mobility of the malleus and to improve the ease of placement of the prosthesis. If the head of the malleus has been removed to maintain the stability of the manubrium, it is often better to stretch rather than cut the tensor tendon.

Malleus present, stapes footplate present (M+S+)

When the malleus is present and only the stapes footplate remains, 2 possible options are available for reconstruction. The first option is to use an incus-stapes prosthesis. The second option is to bypass the malleus and to use a total ossicular reconstruction prosthesis (TORP). Reconstruction using a TORP prosthesis is discussed in the Malleus and incus absent, footplate present section. Several incus-stapes prostheses are available. Two of the most common include the Goldenberg and the Wehrs HAPEX (as seen in the image below) implants (each from Gyrus ENT, Bartlett, Tenn).

For proper placement, the HAPEX shaft of the implants is trimmed after measuring the distance from footplate to the mid portion of the malleus. (Measurement can be performed using any of several commercially available measuring rods.) Then, the shaft is centered on the stapes footplate. While lifting the manubrium, the prosthesis is brought into place under the mid portion of the manubrium. As with the incus replacement prostheses, tension can be increased by moving the prosthesis toward the tip of the manubrium. The middle ear may be packed with gelatin foam for further support. Take care to avoid too much tension on the footplate, which could displace the shaft into the vestibule. The usual length of the incus-stapes prosthesis is 4-6 mm.

Malleus and incus absent, stapes present (M-S+)

A PORP is the best option for ossicular reconstruction when the malleus and incus are absent in the presence of an intact stapes. Numerous PORPs are available. Examples include the Goldenberg HAPEX (Gyrus ENT, Bartlett, Tenn) (as seen in the image below) and the Kurz titanium PORPs (Kurz Medical, Inc, Norcross, Ga) (as seen in the image below).

As with many PORPs, the Goldenberg HAPEX PORP has a rounded hydroxylapatite head and a shaft that can be trimmed. The Goldenberg HAPEX PORP has a malleable connection between the shaft and head that tilts to conform to the orientation of the tympanic membrane. The hydroxylapatite head can be placed directly under the tympanic membrane without the use of a cartilage cover. Initially, the distance from the estimated final resting position of the tympanic membrane (or graft) to the head of the stapes is measured. The shaft of the PORP should be trimmed slightly longer than this measurement. In this way, the prosthesis will "tent" the tympanic membrane (or graft) and help prevent dislocation of the prosthesis. A small notch for the stapedial tendon may be made at the base of the trimmed shaft to provide further stability.

The cannulated shaft is placed over the head of the stapes and the prosthesis is supported with gelatin foam on all sides. The tympanic membrane (or graft) then is draped over the head of the prosthesis. To prevent osseointegration with the canal wall, isolate the prosthesis from the bony external auditory canal with gelatin foam. When using gelatin foam, allowances must be made for its expansion when moist. Expansion of the foam can lift the prosthesis from the stapes, thus causing conductive hearing loss.

The proper length of the prosthesis is important to prevent extrusion. If the prosthesis is too long, the prosthesis can elevate the tympanic membrane too far laterally. Significant elevation of the drum may result in pressure necrosis of the tympanic membrane with extrusion of the prosthesis. On the other hand, if the prosthesis is too short, conductive hearing loss occurs. If the surgeon is new to the use of PORPs, the authors recommend trimming the shaft slightly longer on the first cut, rather than risking making the shaft too short. The exact placement and length then can be determined by trial and error. The usual length for a PORP prosthesis is 2.0-4.5 mm in canal wall up cases and approximately 1 mm in canal wall down cases.

The Kurz Dusseldorf-type BELL PORP is made entirely of titanium. The Kurz PORP comes in various lengths. The flat head of the prosthesis is a grid that allows visualization of the stapes through the grid holes during placement. A cup with 4 malleable bands attaches to the bottom of the shaft. The opening between the bands is designed to accommodate the stapedial tendon. If desired, the bands may be crimped over the stapes capitulum for a more secure fit.

A variation of the BELL prosthesis is the titanium clip prosthesis. ^[8] This prosthesis has elastically flexible feet that grip the stapes head. The clip prosthesis ensures a firm contact between prosthesis and stapes. A cartilage covering over the head of the titanium prosthesis is necessary to prevent extrusion. A cartilage thickness of 500 µm is considered a good compromise between sufficient mechanical stability and low acoustic transfer loss. ^[9]

Kurz has designed a special cartilage cutter to achieve a thickness of 500 µm. As with the Goldenberg HAPEX PORP, gelatin foam is necessary to support the prosthesis. Carefully stabilize the cartilage with one instrument while draping the tympanic membrane (or graft) over the cartilage/prosthesis with another instrument. If not stabilized, the cartilage shifts the prosthesis off the stapes.

Malleus and incus absent, footplate present (M-S-)

In this situation, a TORP is the best option for reconstruction. As with PORPs, numerous TORPs are available. ^[10] The difference between the Goldenberg HAPEX PORP and TORP is that the TORP has a longer, narrower HAPEX shaft. As with the PORP, the Goldenberg HAPEX TORP also has a malleable connection between the shaft and head that tilts to conform to the orientation of the tympanic membrane. The steps for placement of the TORP are the same as that for PORP placement. The only difference in placement is that some surgeons recommend placement of a footplate shoe. The shoe helps to ensure contact and stability with the stapes footplate.

One such shoe is the Goldenberg hydroxylapatite footplate shoe (as seen in the image below). The shoe press-fits on the end of the Goldenberg implant shaft and adds an extra 0.5 mm to the implant length. The footplate shoe is designed to fit between the crura remnants on the footplate. The shoe can be placed onto a tissue graft in the oval window or onto the stapes footplate directly. The shoe can be used with any implant that has an 0.8-mm diameter shaft.

Another type of TORP stabilizer on the footplate is made of cartilage with a specially designed cartilage cutter (Kurz Medical, Inc, Norcross, Ga). This cartilage stabilizer is shaped to the size of the footplate with a small hole in the center to accommodate the shaft of the total ossicular reconstruction prosthesis. Recent auditory studies indicate that the best sound production of a total ossicular reconstruction prosthesis occurs when the shaft of the prosthesis is near the center of the footplate. A dramatic reduction in sound transfer occurs if the prosthesis is even 0.5 mm away from the footplate center.

The usual length for the TORP prosthesis is 4-7 mm for canal wall up procedures and approximately 3 mm for canal wall down procedures.

The Kurz Dusseldorf-type titanium AERIAL TORP (Kurz Medical, Inc, Norcross, Ga) base consists of a piston that rests on the footplate (as seen in the image below). Otherwise, the head is the same as that for the PORP. Placement of the Kurz TORP also requires the use of a cartilage cover. ^[11]

Ask patients to avoid nose blowing, to sneeze with an open mouth, and to avoid lifting heavy objects for the first 2 weeks after surgery. In complying, the patient prevents significant pressure changes in the middle ear that could compromise the result of surgery. Water should be kept out of the ear until the external auditory canal and tympanic membrane are healed.

Ideally, provide follow-up care to patients for a minimum of 3 years (10 y in patients with cholesteatoma). Prosthesis extrusions are most common 1-3 years after ossiculoplasty. After 3 years, the extrusion rate is not significant.

The risks of ossiculoplasty include sensorineural hearing loss, ipsilateral taste disturbance, dizziness, tympanic membrane perforation, infection, tinnitus and, rarely, facial nerve paralysis.

No hearing improvement after surgery is a functional complication. If this occurs, the authors suggest waiting at least 6 months before attempting revision ossiculoplasty. If a tympanic graft has been placed, delay revision ossiculoplasty because the graft must be allowed to thin. In addition, middle ear pressure may change, depending on the status of eustachian tube function. If necessary, revision is easier at 6 months because the tympanic membrane or graft is thin and because decreased vascularity is present in the middle ear.

The status of the tympanic membrane and middle ear has a significant influence on the prognosis of hearing outcomes in ossiculoplasty.

Hearing results typically are classified based on the postoperative air-bone gap. Classifications based on the air-bone gap are usually stratified as excellent (< 10 dB), good (11-20 dB), and fair (21-30 dB). Initial hearing results may diminish with time; therefore, results should be reported at 1, 3, and 5 years.

Prosthesis extrusion has varied from 5-39% in the literature. The rate of extrusion depends on several factors, the most important of which is the status of the middle ear and eustachian tube and the implant material.

The following is a list of situations that generally have a more favorable prognosis for improved hearing compared to their anatomic counterpart:

• Malleus handle present versus handle absent

• Intact stapes arch versus absent arch

• Canal wall up versus canal wall down

• Mastoidectomy not necessary versus mastoidectomy performed

In addition, hearing results generally worsen as the number of revisions increases. The worst results typically occur in patients with congenital ossicular abnormalities.

In general, the better the air conduction and the smaller the preoperative air-bone gap, the greater the chance for a successful hearing result. Goldenberg suggests that this may be because patients with these characteristics have better eustachian tube function, healthier mucosa, and less ossicular damage compared to patients with a poor preoperative air-bone gap. ^[12]

Aeration of a mucosal-lined tympanic cavity is essential for a functioning middle ear. Extrusions of even the best-designed prostheses occur because of abnormal middle ear pathology such as atelectasis, middle ear fibrosis, recurrent cholesteatoma, tympanic membrane perforation, and otitis media.

Various polymers have been developed in an attempt to maximize prosthetic biocompatibility and ease of use, while minimizing the chance of extrusion.

In addition to biocompatibility, cost containment issues have influenced the development of ossicular prostheses. One of the greatest challenges in the future will be to define the appropriate prosthetic design for optimal sound transmission. Consideration of the prosthesis weight, head size, and footplate attachment are future research questions that must be addressed in a scientific biologic model.

Some of the controversial issues of ossiculoplasty include whether revision surgery should be advised and deciding when a hearing aid is a better option for hearing improvement. These controversies have continued for some time and will continue until implant and hearing aid technology are improved and well-controlled studies are performed.

In terms of surgical technique, each surgeon should choose the technique and prosthesis that provides the best result for his or her patients.