Keywords

Describe the flexor tendon “zones”

In the fingers

Zone 1—distal to FDS insertion

Zone 2 (“no man’s land”)—distal to distal palmar crease (A1 pulley), proximal to FDS insertion

Zone 3—distal to carpal tunnel, proximal to distal palmar crease (A1 pulley)

Zone 4—Within carpal tunnel

Zone 5—Wrist and forearm proximal to carpal tunnel

In the thumb

Zone 1—Distal to interphalangeal joint (IP)

Zone 2—Distal to A1 pulley, proximal to IP

Zone 3—Thenar eminence

Zone 4–5—Same as fingers

Describe the flexor pulley system

Five annular pulleys, three cruciate pulleys prevent tendon bowstringing and direct tendon gliding

Odd numbered pulleys (A1, A3, A5) overlay joints (metacarpophalangeal, proximal IP, distal IP) and arise from volar plate of joints

Thumb has A1, Av, oblique, A2 pulleys only

Which pulleys are the most important to prevent flexor tendon bowstringing in the fingers? In the thumb?

Fingers—A2 and A4

Thumb—Oblique pulley

What is the orientation of flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) tendons in the palm and digit and what is the anatomic landmark where the orientation changes?

Palm—FDP deep, FDS superficial

Finger—FDP superficial, FDS deep

FDS tendon splits at “campers chiasm” and dives deep to insert on middle phalanx around FDP which continues distal to insert on distal phalanx

What are the specific functions of the FDP and FDS tendons?

FDP—Flexion of distal IP joint

FDS—Flexion of proximal IP joint

What is the predominate way that tendons receive nutrition?

Diffusion through synovial fluid created by the tendon’s synovial sheath

When can flexor tendon lacerations be treated nonoperatively?

Laceration of <60% tendon width

What is the most important determinant of flexor tendon laceration suture repair strength?

Number of suture strands crossing repair site

Besides crossing sutures, what can be done to improve gliding and strength of a repaired tendon?

Simple, running epitendinous suture

How are chronic flexor tendon injuries typically treated?

Two-stage reconstruction

Stage 1—Silicone rod placement

Stage 2—Tendon graft interposition