Upper extremity

Question 1

Expression of this protein occurs in the zone of polarizing activity (ZPA) on the posterior (ulnar) surface of the developing limb bud and is the main controlling substance for the radial-ulnar axis of development

Answer 1

Sonic Hedgehog protein (SHH)

Question 2

Expression of this protein are the main controlling substances in the apical ectodermal ridge (AER) and are responsible for the proximo-distal axis of limb bud development.

Answer 2

Fibroblast growth factors (FGF)

Question 3

These proteins are expressed in the AER and are also thought to be involved in digital separation, the lack of which leads to syndactyly.

Answer 3

Bone morphogenetic proteins (BMP)

Question 4

Expression of this protein occurs in the apical ectodermal ridge (AER), from the dorsal surface of the limb bud that controls the dorso-ventral axis of limb development.

Answer 4

Wingless proteins (WNT)

Question 5

Describe the technique to reduce a Bennett’s fracture

Answer 5

1. axial distraction
2. pronation
3. abduction of the thumb metacarpal shaft

Question 6

Describe the forces acting on a Bennet’s fracture

Answer 6

the smaller volar-ulnar fragment is retained by the anterior oblique (beak) ligament, while the abductor pollicis longus, thumb extensor tendons, and the adductor pollicis combine to distract the base of the larger shaft fragment radially, dorsally, and proximally.

Question 7

Name 2 sensate flaps for volar thumb tip skin reconstruction

Answer 7

FDMA (kite flap)

Islandized Moberg flap

Question 8

Describe index finger pollicization (for Blauth type IIIB thumb deficiency and higher)

Answer 8

In pollicization, the index finger is transferred on its neurovascular bundle and a new thumb carpometacarpal (CMC) joint is created using the metacarpophalangeal joint of the index finger.

The tendons and muscles of the index finger are used to recreate functions of the new thumb.

The extensor digitorum communis is used for the abductor pollicis longus,

the dorsal interosseus becomes the abductor pollicis brevis,

the palmar/volar interosseous becomes the adductor pollicis.

The extensor indicis proprius is used for the extensor pollicis longus.

The flexor tendon is not typically disturbed.

Question 9

In pollicization: what is the new function of the extensor digitorum communis

Answer 9

abductor pollicis longus

Question 10

In pollicization: what is the new function of the extensor indices proprius

Answer 10

extensor pollicis longus

Question 11

In pollicization: what is the new function of the first dorsal interosseous muscle

Answer 11

abductor pollicis brevis

Question 12

In pollicization: what is the new function of the first palmar interosseous muscle

Answer 12

adductor pollicis

Question 13

typical tendon transfer to restore wrist extension

Answer 13

pronator teres (median nerve innervated) to ECRB