Yumoto Orthopaedic Clinic (JP HOME) is the Originator of
  Percutaneous Trigger Finger Release Surgery with Guided Knife		 Since
2011/07/31		  
Mechanism of Guided Knife

- Palmar Skinslide -
･ Author of this Home Page has named Trigger Finger Release Surgery with Guided Knife as GK-PTFR Surgery.

･ GK-PTFR is performed with only 2mm Skin incision.

･ 2mm is the width of Guided Knife's cutting edge.

･ Once Guided Knife is inserted, it can divide whole length of A1 pulley (1.5 cm long) without widening the inistial wound.

･ The secret of Guided Knife division lies on the nature of Skin, which never Streches but Slides !

Skin slide

Epidermal slide and A1 pulley length
[Slidable palmar epidermis]

To understand one of the characteristics of palmar epidermis, you may perform a simple experiment on your own hand.

{ Step 1}
  • Fingers in slight flexion (Illustration at right).
  • Press firmly on the palm with a finger tip of the other hand, and try to move the contact area distally and proximally.
  • You will find that the palmar epidermis moves a considerable distance in longitudinal direction.
  • Y's Guided Knife technique consists in making use of this feature.
I have an impression from clinical experiences that maximal distance of skin excursion might be shorter than A1 pulley length in many cases. This will be discussed later in operation techniques.

{ Step 2}
  • Fingers in maximal extension.
  • Perform the same maneuver as "step 1" with the fingers fully extended.
  • You will find that slidable feature completely disappears from the palmar epidermis.
[Length of A1 pulley]

Wilhelmi's cadaveric study on 256 fingers has disclosed that mean A1 pulley length of Index, Middle and Ring fingers is 1.17±0.02 cm.

He also reported that distance "a" (PDC-PIP) of illustration at right is nearly equal to distance "b" (PDC-proximal A1 line). This is a very encouraging argument for hand surgeons who perform PTFR where A1 pulley division initiates from proximal edge toward distal.
(PDC: palmar digital crease, PIP: proximal interphalangeal crease)

On the other hand, Y's Guided Knife technique is unique that A1 pulley division initiates from distal edge toward proximal.

Wilhelm B.J. Trigger Finger Release with Hand Surface Landmark Ratios: An Anatomic and Clinical Study. Plast Reconstr Surg. 108:908-915, 2001.
[Pulley system of hand]
There are 5 pulleys from A1 to A5, where character A stands for annular. There are also 4 pulleys from C0 to C3, where C stands for cruciate or cruciform.
Trigger finger release operation is aimed at dividing A1 pulley apart, and in very rare cases C0 pulley distal to A1 needs to　be divided too.

[Synonyms]
A1 pulley, A1 tendon sheath, A1 sheath, the A1, tendon sheath, ligamentous tendon sheath, annular pulley, first annular pulley.