Ossicular Prostheses (Middle Ear and Stapes Implants)
Indications for Use
The surgeon must fully assess the risks and benefits to the patient prior to the decision to implant ossicular prostheses. The physician must exercise medical judgement and consider the patient’s complete medical history. Medtronic Xomed ossicular prostheses are indicated for the functional restoration of sound energy conduction in the middle ear as reconstructive devicesor artificial replacement for the natural ossicles of the middle ear. Reconstruction or replacement of all or part of the ossicular chain may be necessary to correct structural damage of the middle ear ossiclesor conductive hearing loss resulting from a number of pathologic conditions, including but not limited to:
- Chronic middle ear disease
- Otosclerosis
- Congenital fixation of the stapes
- Secondary surgical intervention to correct for a significant and persistent conductive hearing loss from prior otologic surgery
- Surgically correctable injury to the middle ear from trauma
Contraindications
Certain conditions may preclude the selection of ossicular prostheses implants as a means of restoring conductive hearing loss including:
- The presence of middle ear infection which could result in displacement of the implant(s)
- Conductive hearing loss which may be restored by non-invasive methods
- The operative ear is the better or only hearing ear. Reduced hearing or total deafness is at risk in such cases.
Possible Adverse Effects
Surgery of the middle ear involves manipulation of fragile temporal bones and exposes inner ear structures to the risk of surgical trauma and infections. Serious complications may arise either during or after surgery which may result in irreparable damage to these otologic structures and their functions causing irreversible partial or total loss of hearing. Subsequent surgical procedures may be required to correct these conditions if possible.
Complications which may occur include, but are not limited to:
- Sensorineural deafness due to trauma during surgery
- Granuloma and perilymph fistula
- Post surgery displacement of the implant due to the development of scar tissue
- Recurrence of oval window fixation
- Vertigo
- Incus necrosis
- Round window closure
- Labyrinthitis
- Otitis media
Precautions/Intraoperative
A high degree of surgical skill is required for the proper implantation of any ossicular prostheses. Surgeons performing middle ear surgery should have received specific training in the reconstruction and replacement of the middle ear ossicles prior to attempting implantation of Medtronic Xomed ossicular prostheses. Extreme caution must be exercised by the surgeon during surgery to safeguard against undesirable results and postoperative complications.implant should be trimmed (or a shorter implant selected) if it is too long for the vestibule to avoid any contact with sensitive inner ear structures.
At a minimum, the following precautions must be taken:
- To avoid postoperative vertigo and/or loss of inner ear functions, the surgeon should carefully assess the length of the implant in relation to the depth of the middle ear vestibule. The
- To safeguard against postoperative sensorineural hearing loss, extreme care must be taken to avoid traumatizing the inner ear structures by unnecessarily contacting the inner ear structures with surgical instruments or the implant(s) or through the removal of perilymph from the vestibule.
- As a precaution against implant extrusion through the tympanum, tissue grafts should be used as an interface between the implant and the tympanum. Similarly, a tissue graft should be employed over the stapes footplate, or alternatively, over the oval window in stapedectomy procedures to help prevent perilymph fistula or leakage of perilymph.
- To prevent potential separation of the shoe component (if applicable), verify prosthesis shaft is fully seated within the shoe prior to placement.
Precautions/Postoperative
Following surgery, both surgeon and patient must be alert to any sign of adverse effects from surgery and the patient should be advised of the proper care of the operative ear. The following postoperative precautionary measures are recommended:
- If there is any suspicion of oval window granuloma or fistula during the postoperative recovery period, an emergency exploratory tympanotomy and correction of the condition should be performed immediately.
- The patient should be advised of the importance of keeping the operative area clean and dry until healing is complete and dressings are removed. Specific instructions on how to maintain proper hygiene of the operative ear should be given to the patient.
- Magnetic Resonance Imaging (MRI) PRECAUTIONS:For ossicular prostheses with metal components:
Medtronic Xomed manufactures metal ossicular prostheses only from non-ferromagnetic metals and Austenitic medical grade stainless steel; however, slight magnetism can be characteristic of Austenitic stainless steel. While there are no known reports of MRI-related adverse effects to a patient due to any Medtronic Xomed ossicular prostheses, caution is advised when administering MRI procedures. Caution is particularly advised when magnetic fields above 1.5 Tesla are used, as the effects at such levels have not been thoroughly studied. Additionally, image artifact can occur due to the material composition of the prosthesis. Because of the potential for such artifact, alternative imaging techniques, such as CT scanning, should be considered.
Additional Information
Hydroxylapatite is the basic inorganic constituent of living bone tissue. Like any ceramic material, there is some risk of breaking or cracking the implant under certain conditions. In the event that minor modifications of a dense H/A head or shaft are required, it is advisable to perform all trimming or contouring with a diamond burr using copious amounts of irrigation. Smooth, even brushing strokes should prevent inadvertent breakage. Reults, based on almost 10 years of clinical experience using dense hydroxylapatite in the middle ear, suggest that implants can be placed in direct contact with the tympanic membrane without the added risk of extrusion.
However,the use of cartilage or other suitable autogenous tissue as an interface between the implant and the tympanic membrane should be left to the surgeon’s experiences and preferences.
FLEX H/A is a homogenous, nonporous composite of two well-known biomaterials: hydroxylapatite and silicone. The result is a unique bioactive material which provides excellent tissue interface and can be easily trimmed with a surgical knife. Both FLEX H/A and dense HA can be manufactured to various specifications allowing for the reconstruction of the middle ear ossicular chain.
