Within the Temporal Bone · Chapter 12 · Part III · The middle ear and nerve
The Stapes and Oval Window
One technique, followed in order, under the facial nerve
Bench mode: one step per screen, large type, screen kept awake. Tap, use the arrow keys or say “next”.
- Specimen
- Adult temporal bone with drum, chain and chorda intact; side recorded
- Bench time
- One session; your instructor sets the target
- Instruments
- Curette or small diamond, joint knife, crurotomy scissors, perforator or microdrill, measuring rod, training piston
- View
- Low power for exposure; high power at the footplate
- Before this
- Chapter 5 (flap, survey) and Chapter 11 (joint division)
By the end you can
- Expose the niche: facial nerve, footplate, tendon, incus
- Measure from the incus to the footplate
- Remove the superstructure without moving the footplate
- Make a fenestra, place a training piston and record any unplanned footplate event
- Distinguish stapedotomy from stapedectomy
A small, clean fenestra with a training piston central in it and its loop closed on the incus, still in place after the flap is replaced, with every footplate event recorded.
Patient selection. Stapes surgery requires audiological assessment, diagnosis, counselling and attention to anatomical or inner-ear factors; this chapter is a supervised anatomical and technical exercise.
The landmark chain
Each landmark leads to the next. Tap any one to see every station where it appears.
12.1 Establish the anatomy before the procedure
The stapes exercise is a sequence. There are legitimate variations, including whether the fenestra is made before or after the superstructure is removed, and each protects the footplate in its own way. Your instructor chooses and demonstrates one coherent technique; follow it in order and do not mix steps from different methods.
A fixed footplate is a clinical finding made in context; a fixed or desiccated specimen cannot establish otosclerosis. In patients, stapes surgery requires audiological assessment, diagnosis, counselling and attention to anatomical or inner-ear factors that may change its suitability. This chapter is a supervised anatomical and technical exercise, not a patient-selection protocol.
Inspect the footplate after every step. A change you did not plan stops the sequence.
12.2 · The 6 stations
Expose the niche
- Raise the tympanomeatal flap and fold it forwards over the handle.
- Lower the posterosuperior canal wall (scutum) with a curette or diamond until you see the pyramidal eminence behind and the facial nerve above the footplate. If an overhang still limits the view, improve the exposure under supervision; never work round it with an unseen instrument tip.
- Preserve the chorda; mobilise it gently out of the field rather than divide it.
- Name the long process of the incus, the incudostapedial joint, the stapedius tendon, the crura, the footplate and the tympanic facial nerve, and judge the space under the nerve.
Facial nerve, pyramid and footplate seen together with the chorda intact.
The nerve overhangs the footplate or looks exposed. Record it and review the plan; do not force the standard sequence into the niche.
Measure and plan
- Measure from the lateral surface of the long process of the incus to the footplate, the rod held along the line the prosthesis will take.
- Decide the prosthesis system and its attachment before changing the chain.
- Size from your measurement and the manufacturer’s instructions; there is no universal piston length or fixed instrument excursion.
A measured distance, a chosen device and a written plan.
You cannot see the footplate along the measuring line. Improve the exposure first.
Divide the joint and the tendon
- Divide the incudostapedial joint, controlling the direction of force and never pushing the stapes inwards.
- Divide the stapedius tendon.
- Keep the long process of the incus intact; do not use it as a lever.
- Inspect the footplate: an apparently intact plate may have moved or cracked.
Joint and tendon divided; the footplate has not moved.
The footplate has moved or cracked. Stop and seek review; do not go on to the fenestra because it is next.
Remove the superstructure
- Divide or fracture the crura as your technique describes, the force directed away from the vestibule.
- Lift the superstructure out without traction on the footplate.
- Inspect the footplate again for position, fracture and mobility.
Superstructure out, footplate intact and in place.
The footplate is mobile or depressed. Stop, call your instructor and record it separately from the planned opening; in a patient this is a different operation.
Make the fenestra
- Choose the site in the footplate, clear of the nerve.
- Open the footplate with controlled depth under continuous view. Drill, laser and hand methods each need equipment-specific instruction; laser settings are not generalised from one system to another.
- Do not suction or probe within the vestibule.
- Inspect the fenestra and the remaining footplate.
A small, clean fenestra; the rest of the footplate intact and still.
The footplate fractures or floats. Stop and seek review.
Place the prosthesis
- Introduce the training piston according to its instructions, the shaft into the fenestra and the loop over the long process of the incus.
- Secure the attachment by the method for that device, coupling it without damaging the incus or displacing the footplate.
- Check that the piston moves with the incus when the handle is touched and does not bind on the edge of the fenestra.
- Inspect chorda, incus, footplate and prosthesis; replace the flap, look again, and record any footplate mobilisation, fracture or unplanned entry into the vestibule.
Piston central in the fenestra, loop closed on the incus, all still in place after the flap is replaced.
The piston binds or the loop slips. Remove and reassess; do not crimp harder.
12.3 Restricted exposure and unexpected findings
A prominent or displaced facial nerve can limit access to the oval window; a vascular or inner-ear anomaly changes the clinical problem. Both call for specialist reassessment, not for forcing the standard sequence into an unsuitable field. In the laboratory, keep the abnormal relationship for study.
The quality of the exercise lies in recognising such events as much as in completing the reconstruction.
In stapes work the footplate tells you when to stop. Look at it.
◉ 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.
12.4 Fault finding
| What you see | Probable cause | Correction |
|---|---|---|
| Long process bent or fractured | Used as a lever, or loop over-crimped | Never lever; crimp to the device instructions |
| Chorda divided | Taken into the curette | Mobilise it out of the field first |
| Steps mixed from two techniques | No single plan | Choose one sequence before you start |
| Footplate fracture found only at the end | Footplate not inspected after each step | Inspect it after every change |
12.5 Viva at the bench
The footplate becomes mobile before the planned fenestration. What changes?
The sequence stops. It is recorded separately from the planned opening and reviewed with the instructor; in a patient a mobilised footplate makes it a different operation, not a step to work past.
Why is there no universal piston length?
The distance from the long process of the incus to the footplate varies between ears; the length is sized from the measurement along the prosthesis line and the chosen device’s instructions.
What distinguishes a stapedotomy from a stapedectomy?
A stapedotomy makes a small fenestra in the footplate for the piston; a stapedectomy removes a larger part or all of the footplate and seals the window with tissue before the prosthesis is placed.
One best answer
12.6 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 |
|---|---|---|---|
| Niche exposed with the chorda intact | |||
| Incus-to-footplate distance measured along the prosthesis line | |||
| Superstructure removed, footplate intact | |||
| Controlled fenestra, vestibule not entered | |||
| Piston coupled and moving with the incus | |||
| Every footplate event recorded |
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 stapedotomy in the theatre
Sources and credits
- Companion video: Otosclerosis, endoscopic stapedotomy. Dr Bhushan Kathuria & Team. youtu.be/T1TbiFLobA8
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.
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