Within the Temporal Bone · Chapter 11 · Part III · The middle ear and nerve
The Ossicular Chain and Reconstruction Principles
Reconstruct from what remains, not from what you remember
Bench mode: one step per screen, large type, screen kept awake. Tap, use the arrow keys or say “next”.
- Specimen
- Adult temporal bone with intact canal and drum; chain documented in Chapter 5; side recorded
- Bench time
- One session, including graft preparation; your instructor sets the target
- Instruments
- Joint knife, fine hook, cup forceps, ossicle holder, small diamond burr, measuring rod, training prostheses
- View
- Low power in the ear and on the ossicle holder; higher power at the joints
- Before this
- Chapter 5 (flap and survey) and Chapter 7 (joint division and incus removal)
By the end you can
- Name every part of the malleus, incus and stapes and their joints
- Divide the incudostapedial joint and remove the incus without moving the footplate
- Inspect the residual platform: stapes superstructure, footplate, handle and drum
- Sculpt an incus for interposition and seat it between handle and stapes head
- Recheck the reconstruction after the flap is replaced, and record its limits
A sculpted incus seated between the handle and the stapes head, stable at both contacts after the flap is replaced, with the residual anatomy, material, support and views recorded.
Hearing, aeration, long-term stability or extrusion: the bench teaches handling, sizing and placement only. Prosthesis selection follows the chosen system’s instructions.
The landmark chain
Each landmark leads to the next. Tap any one to see every station where it appears.
11.1 Study the intact chain first
The malleus, incus and stapes are one mechanical system, held by joints, ligaments and two tendons. Reconstruction begins with knowing that system intact, then with an honest account of what is left. The bench teaches handling, sizing and placement, not hearing, aeration, long-term stability or extrusion; do not claim them.
Study every part of the chain through every available approach and photograph it before you change it. Assess continuity with controlled movement, under supervision.
A preserved specimen may be stiff for reasons unrelated to disease, and a harvested chain may already be disrupted: mobility does not prove normal mechanics, and an immobile chain in a fixed specimen is not otosclerosis.
11.2 · The 5 stations
Record the intact chain
- Raise the tympanomeatal flap and lower the scutum enough to see the incudostapedial joint and the stapes.
- Name the handle of the malleus, the long process of the incus, the joint, both crura where visible and the stapedius tendon.
- Test transmission at the handle only, watching the stapes head.
- Record dislocation, missing parts and stiffness before you go on.
The chain photographed and its condition written down.
The chain is already disrupted. Plan the exercise from what is present, not from the textbook chain.
Divide the joint, remove the incus
- Divide the incudostapedial joint under direct vision, moving parallel to the footplate, so that no force reaches it.
- Leave the stapedius tendon intact; it steadies the stapes.
- Release the incudomalleolar joint and lift the incus out with a controlled movement.
- Keep it in a labelled container with the side recorded; any damage to its processes or facets decides whether it can still be used.
Incus removed intact; the stapes did not move.
The stapes rocked. Stop and inspect the footplate with your instructor before anything else.
Inspect the platform
- Is the stapes superstructure present? Is the footplate intact, and is it mobile?
- Where does the handle of the malleus lie in relation to the stapes head, and is the drum (or intended graft) attached to it?
- Size the gap between handle and head as instructed, from two directions.
- A fragment near the oval window may not be debris: find its attachment before you remove it. Reaching a region with an instrument does not make contact harmless.
The residual chain described in one sentence: what is present, what is mobile, where the handle lies.
The footplate looks unstable or has moved. Inspect it with your instructor; never fit a prosthesis over it, which disguises the injury.
Sculpt the incus
- Hold the incus firmly in an ossicle holder, never in your fingers, and irrigate while you drill.
- Remove the long process.
- Drill a shallow socket to seat on the stapes head and a groove to lie under the handle of the malleus.
- Shape for the gap you sized, not for a standard size: the geometry depends on the defect and the support points.
A graft with a socket and a groove that match the platform described in Station 3.
The graft fractures. Record it; a fractured graft is not used.
Seat the graft and recheck
- Place the socket on the stapes head and rotate the graft until the groove lies under the handle.
- Check contact at both points, without tension driving the stapes medially; touch the handle gently and watch the stapes move with the graft.
- Support the graft while you replace the flap, then look again from more than one direction: alignment often changes when tissue is laid back, and packing must not hide an uncertain contact.
- Record the residual anatomy, the material, the support and the final position, and from which views you inspected it.
Graft stable at both contacts after the flap is replaced.
The graft moves when the flap goes down. Lift the flap, correct the seating, and record the change.
11.3 Reconstruct from what remains
A partial and a total reconstruction answer different residual configurations; the choice depends on what remains to support and transmit sound. A strut that is too long imposes excessive tension; poor support or orientation lets it displace.
Learn the line of transmission and the points of contact, and do not judge success by whether a component balances for a moment. Nothing pushes, pulls or levers on the footplate, least of all when its superstructure is gone. Material, prosthesis and stabilisation vary with the ear and technique; follow the selected system’s instructions, not a generic length or angle.
A reconstruction is finished when its contacts are seen, not when it balances.
◉ See it on real specimens
Real dissection and operative photographs published openly by other surgeons and institutions. They open on the original site with full credit to the authors; they are not copied into this companion. Compare them with the drawings above.
11.4 Fault finding
| What you see | Probable cause | Correction |
|---|---|---|
| No record of the original chain | Documentation skipped | Photograph and describe before removal; review the movement behind each fault |
| Graft tilts off the head | Socket too shallow or off-centre | Re-drill the socket centrally |
| Stapes pushed medially | Graft too long | Reshape; contact without tension |
| Fragment pulled from the oval window region | Attachment not identified | Find what holds it before retrieving it |
11.5 Viva at the bench
The reconstruction looks stable before flap replacement. Is the exercise finished?
No. Alignment often changes when the flap is laid back; the contacts must be checked again from more than one direction after replacement, and packing must not hide an uncertain contact.
What decides between a partial and a total reconstruction?
What remains to support and transmit sound: with the stapes superstructure present, a graft or partial prosthesis to the head; with only a mobile footplate, a total prosthesis to the footplate.
What is the risk of a strut that is too long?
Excessive tension, driving the stapes or footplate medially; poor support or orientation, on the other hand, lets it displace.
One best answer
11.6 My dissection log
Saved on this device only. Print it or send the summary to your fellowship coordinator for review.
Score the dissection · review order
| Item | 0 · not achieved | 1 · partly | 2 · achieved |
|---|---|---|---|
| Intact chain photographed and described | |||
| Incus removed without moving the stapes | |||
| Residual platform described in one sentence | |||
| Graft shaped to the sized gap | |||
| Contacts seen after flap replacement | |||
| Limits of the bench stated |
The review order is a teaching method, not a validated scoring instrument. Structured end-product scales such as the Welling scale have been studied for rater reliability; they assess the dissection, not operative outcome, but they make feedback specific.
Before your first ossiculoplasty in the theatre
Sources and credits
- Companion video: Tympano-Ossiculoplasty, PORP and malleus relocation. Dr Bhushan Kathuria & Team. youtu.be/1neAvRUgQmU
Real dissection photographs with numbered drawings: Bassett Collection, Stanford University (CC BY-SA 4.0). Classic anatomical and operative plates: Gray’s Anatomy of the Human Body (1918, drawings by H. V. Carter) and Burghard’s A System of Operative Surgery (1909), both public domain, credited beside each plate. Remaining diagrams and charts: Dr Bhushan Kathuria & Team, not to scale. Operating-theatre frames and clips: our theatre, patient consent taken, identity not shown. Atlas photographs: Open Access Atlas of Otolaryngology (CC BY-NC 3.0), with their authors credited beside each image. This edition uses no AI-generated images. For professional education alongside supervised instruction and local protocols.
Dr Bhushan Kathuria & Team · Reg. No. HN-017323, Haryana Medical Council · A GeNext MedEd Foundation surgical education initiative.
‹ Chapter 10: Canal Wall Down Dissection and Cavity DesignChapter 12: The Stapes and Oval Window ›
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