- See:
Pulley Reconstruction:
- Flexor Tendon Pulleys:
- A1 pulley:
- arises from volar plate of MP joint, beginning 5 mm proximal to the MP joint and ending at the base of the proximal phalanx;
- average length of A1 pulley is 1 cm;
- proximal edge of the 1st
annular pulley lies about 2 cm from the proximal finger crease;
- distal edge of A1 pulley lies about 1 cm from the proximal finger crease;
- note that the proximal phalangeal crease which lies over the mid portion of the proximal phalanx, and that the A2 pulley begins and
ends in the proximal half of the proximal phalanx;
- hence, a tendon sheath incision which extends past the level of proximal phalangeal crease will probably incise most the A2 pulley;
- note that at the level of the A1 pulley, the FDS flattens out and bifurcates, allowing the FDP tendon to pass superficial;
- A2 pulley
- arises from periosteum of proximal half of the proximal phalanx;
- total length is 20 mm, along the mid portion of the proximal phalanx;
- of all of the flexor tendon sheaths, this is probably the most important;
-
vascular considerations:
- their is a avascular zone within
the intrasynovial portion of the FDS and FDP tendons under the A2 pulley;
-
distal to the A2 pulley, a digital arterial ladder branch provides arterial inflow to the vinculum to FDS and long vinculum FDP;
- in study by G. Mitsionis MD et al (JHS 1999), it was found that 25% of A2 or A4 pulleys may be excised either separately or in combination;
- these authors noted that even excision of upto 75% of the pulley resulted in only minimal decreases in PIP angular ROM;
- references:
-
The second annular pulley: a histologic examination
-
The effect of partial A2 pulley excision on gliding resistance and pulley strength in vitro.
-
"Venting" or partial lateral release of the A2 and A4 pulleys after repair of zone 2 flexor tendon injuries.
- C1 pulley;
- A3 pulley:
- arises from volar plate of PIP joint;
- in the report by Jin Bo Tang, MD et al, the authors studied the effects of the A3 pulley and adjacent sheath integrity on tendon function
at the proximal interphalangeal (PIP) joint was investigated in 21 fingers in 7 fresh-frozen cadaver hands;
- 11 fingers were tested after incision of the A3 pulley, of the A3 pulley and its distal sheath up to the A4 pulley, and of the sheath from the A3 to A4 pulleys;
- tendon bowstringing was 0.3 mm after incision of A3 pulley, 0.6 mm after incision of A3 pulley with its distal sheath, 0.8 mm after incision
of pulley with its proximal sheath, 1.4 mm after incision of sheath from A3 to A4 pulleys, and 1.6 mm after incision of sheath
between the A2 and A4 pulleys;
- results suggest that the sheath adjacent to the A3 pulley plays an important role in restraining tendon bowstringing at the PIP joint, whereas
A3 pulley alone is of little importance;
- references:
-
Effect of A3 pulley and adjacent sheath integrity on tendon excursion and bowstringing. Tang, MD. J Hand Surg 2001;26A:855-861.
-
The A3 pulley
- C2 pulley;
- A4 pulley
- arises from periosteum of mid-portion of middle phalanx;
- this is the second most important flexor tendon sheath pulley (after the A2);
- when the FDS tendon is lost, the A4 pulley becomes most essential;
- there is an avascular zone of the FDP underneath the A4 pulley;
- in study by G. Mitsionis MD et al (JHS 1999), it was found that 25% of A2 or A4 pulleys may be excised either separately or in combination;
- these authors noted that even excision of upto 75% of the pulley resulted in only minimal decreases in PIP angular ROM;
- ref:
"Venting" or partial lateral release of the A2 and A4 pulleys after repair of zone 2 flexor tendon injuries.
- C3 pulley;
- A5 pulley arises from volar plate of the DIP joint;
-
Anatomy and histology of the A5 pulley
Three-loop technique for A2 pulley reconstruction.
Digital flexor tendon sheath: an anatomic study. B. Strauch, de Moura W. J. Hand Surgery. Vol 10-A. 1985. 785.
Anatomy of the finger flexor tendon sheath and pulley system. JR Doyle. J. Hand Surg. Vol 13-A. 1988. p 473.
Palmar and digital flexor tendon pulleys.
Year Book: Postnatal Growth and Development of the Flexor Tendon Pulley System. Flake-J. Light-TR. Ogden-JA. J Pediatr Orthop. 1990. 10. pp 612-617.
Tendon and pulleys at the metacarpophalangeal joint of a finger.
Effect of pulley integrity on excursions and work of flexion in healing flexor tendons
A2 pulley incision or one slip of the superficialis improves flexor tendon repairs.
Flexor tendon pulley V-Y plasty: an alternative to pulley venting or resection.
"Venting" or partial lateral release of the A2 and A4 pulleys after repair of zone 2 flexor tendon injuries.
