Flap Knife

What it is

The flap knife (Plester type) is a fine otological knife with a small, round blade set on a slender, straight shaft that tapers toward the tip. Its cutting surface is the sharpened edge of a rounded, flag-shaped blade — not a lancet point. That rounded shape is deliberate: it lets the surgeon incise along the curved wall of the ear canal and slide beneath the canal skin to raise the tympanomeatal flap, rather than piercing tissue with a tip. Working close to the fibrous annulus, ossicles, and chorda tympani, a knife with no sharp point is safer to advance under the microscope. The blade both cuts the canal incision and elevates the flap, and is also used to extend pre-formed incisions in the tympanic membrane.

When & how it's used

Used at the start of the middle-ear dissection in a transcanal or endaural approach, once the speculum is seated and the field is prepared. The surgeon uses the flap knife to make the curved canal-wall (tympanomeatal) incision and to raise the tympanomeatal flap — the skin-and-fibrous-layer flap lifted medially to reach the fibrous annulus and enter the middle ear. It is used across myringoplasty, tympanoplasty, and ossiculoplasty. In cartilage tympanoplasty it is also used to shave the cartilage island when fashioning the peripheral cartilage ring that supports the graft.

The flap knife earns its name from its job: raising the tympanomeatal flap, the skin-and-fibrous-layer flap that is the surgeon’s route into the middle ear in a transcanal or endaural approach. It is a small, round-bladed knife — the design most often attributed to Plester — and the rounded blade is the whole point of it. A tipless, sharpened round edge can be run along the curved wall of the ear canal to make the canal incision and then slid under the canal skin to lift the flap, all without a piercing point near the delicate structures beneath. It is not a stabbing or lancet-style knife.

Design features

• Round, sharpened blade — the cutting surface is the edge of a small rounded (flag-shaped) blade, not a point; it both incises the canal wall and elevates the flap
• Slender, tapered straight shaft — narrows toward the tip for access through an aural speculum under the operating microscope without fouling the line of sight
• Atraumatic profile — the absence of a sharp tip makes the knife safer to advance close to the fibrous annulus, ossicular chain, and chorda tympani
• Stainless steel, autoclavable — compatible with standard steam sterilisation

Raising the tympanomeatal flap — why the design matters

The tympanomeatal flap is the only route to the middle ear in a transcanal approach, so how cleanly it is raised shapes the whole operation:

• Flap viability — a flap lifted in the correct plane, with clean edges, heals more predictably
• Haemostasis — a controlled incision and sub-flap elevation bleed less than torn tissue
• Re-draping — at closure the flap must lie flat over the graft; a cleanly raised flap returns cleanly to position
• Exposure — a well-elevated flap gives full sight of the annulus and middle ear; a poorly raised one limits the view

The round blade supports all of this: it can be angled against the curved canal wall and worked in the subperiosteal/sub-flap plane, cutting and elevating in the same motion rather than relying on a point.

Where it sits in the instrument sequence

Exact technique varies by surgeon and approach, but in a typical transcanal tympanoplasty the flap knife is an early-step instrument, used before the finer dissection tools:

1. Flap knife (round blade) → curved canal-wall incision and elevation of the tympanomeatal flap (this instrument)
2. Sickle knife → finer work at the fibrous annulus and middle-ear mucosa
3. Periosteal elevator / round knife → continued flap reflection and annulus elevation
4. Micro cup / crocodile forceps → middle-ear tissue handling and graft placement

The flap knife and the sickle knife are complementary, not interchangeable: the flap knife does the broad canal incision and flap elevation; the sickle knife does the delicate annular and mucosal cuts.

Frequently Asked Questions

What does a flap knife do in ear surgery? It makes the curved incision in the ear canal wall and raises the tympanomeatal flap — the skin-and-fibrous-layer flap that is lifted to reach the fibrous annulus and enter the middle ear. It both cuts and elevates, and is also used to extend pre-formed incisions in the eardrum.

Why does the flap knife have a round blade instead of a sharp point? Because the round, sharpened edge can be run along the curved canal wall and slid beneath the canal skin to elevate the flap, without a piercing tip. Near the fibrous annulus, ossicles, and chorda tympani, a tipless blade is safer to advance under magnification than a lancet-style knife.

What is the difference between a flap knife and a sickle knife? The flap knife (round blade) makes the broad canal-wall incision and elevates the tympanomeatal flap. The sickle knife has a fine hooked blade used for more delicate steps — incising the fibrous annulus and the middle-ear mucosa. They are used in sequence and for different tasks; neither replaces the other.

Is the flap knife the same as the Plester knife? “Plester flap knife” refers to the round-bladed flap knife design commonly attributed to the otologist Plester. The terms are used interchangeably for this style of round-edged flap-elevating knife.

Why not use a general scalpel to raise the flap? A standard scalpel cannot fit through an aural speculum under the operating microscope without fouling the field, and its point is poorly suited to sliding beneath the canal skin. The flap knife’s slender shaft, round blade, and scale are made specifically for working within the ear canal under magnification.