Sickle Knife

What it is

The Sickle Knife (also known as the Rosen knife or sickle-shaped myringotomy knife) is a fine, angled blade mounted on a slender handle, with a curved tip that resembles a sickle or crescent. The blade orientation allows the surgeon to make precise, controlled incisions at angles that a straight knife cannot reach — particularly the posterior canal wall skin and the fibrous annulus — without the handle obstructing the operating microscope view.

When & how it's used

The sickle knife is used at the flap-raising stage of tympanoplasty and ossiculoplasty. After the initial canal incisions are made (typically with a flap knife), the sickle knife is used to develop the tympanomeatal flap by separating skin from underlying bone along the posterior and inferior canal walls. It is also used to incise the annulus fibrosus to enter the middle-ear space, and for fine dissection around the ossicular chain where blunt elevation is insufficient.

The sickle knife is one of the few instruments in ENT surgery whose shape is immediately recognisable — the crescent blade is designed around a single anatomical problem: how to make a clean incision along the posterior canal wall and into the fibrous annulus when the ear canal blocks straight-line instrument access. No straight-blade knife can do this without the handle fouling the speculum or the microscope view. The sickle curve solves it.

Design features

• Crescent blade tip: cutting edge on the inner curve; allows incision along the canal wall with the handle held outside the speculum
• Slender shaft: passes through an aural speculum with clearance for microscope illumination
• Fine blade edge: factory-sharpened for clean skin and periosteum incision without tearing
• Stainless steel, autoclavable: compatible with standard steam sterilisation protocols

Role in tympanoplasty

The sickle knife typically appears after the initial canal incisions and works in sequence with the flap knife and elevator:

1. Flap knife makes the primary posterosuperior and inferior canal incisions
2. Sickle knife develops the flap by separating canal skin from underlying bone and incising the annulus fibrosus
3. Round knife or elevator completes flap elevation and reflects it anteriorly

The annular incision is the most technically demanding step the sickle knife performs — the annulus fibrosus is a tough fibrocartilaginous ring, and a blunt or poorly angled blade will tear the drum remnant rather than cut cleanly through the annulus. A sharp sickle knife, correctly angled, makes this a single controlled move.

Frequently Asked Questions

What is a sickle knife used for in ear surgery? It is used to raise the tympanomeatal flap — the skin-and-periosteum flap on the posterior canal wall that is reflected to expose the middle ear. Specifically, it separates canal skin from bone and incises the fibrous annulus to enter the tympanic cavity.

Why is it called a sickle knife? The blade tip is shaped like a sickle or crescent — curved so that the cutting edge faces inward along the curve. This geometry allows incisions along the posterior canal wall while the handle remains outside the aural speculum, avoiding obstruction of the operating microscope.

Is the sickle knife the same as a Rosen knife? The terms are often used interchangeably. The Rosen knife, introduced by Samuel Rosen in the context of stapedial surgery, has a similar sickle-blade profile. In common clinical usage, “sickle knife” describes any instrument of this curved-blade type; the Rosen is one specific variant.

What is the difference between a sickle knife and a flap knife? The flap knife makes the initial straight incisions in the posterior canal wall to define the flap margins. The sickle knife then develops the flap by working along those incision lines to separate tissue from bone and incise the annulus. They work in sequence, not interchangeably.