CHAPTER 43: Arm, Forearm, and Hand Lacerations

Question 1

TRUE or FALSE?

No distinct threshold for infection from time of injury to closure

Answer 1

TRUE

There is no distinct threshold for infection from time of injury to closure, but wounds sutured >12 hours after injury

Question 2

TRUE or FALSE?

Agents containing epinephrine cannot be used in digital nerve blocks

Answer 2

FALSE

The belief that a local anesthetic with epinephrine should not be used for digital nerve blocks is without evidence, and clinical observation studies have found agents containing epinephrine safe for digital nerve blocks.

Question 3

Motor Testing of the Peripheral Nerves of the Upper Extremity (Table 43-1 page 292)
Dorsiflexion of wrist

Answer 3

Radial nerve

Question 4

Motor Testing of the Peripheral Nerves of the Upper Extremity (Table 43-1 page 292)
Thumb abduction away from the palm
Thumb interphalangeal joint flexion

Answer 4

Median nerve

Question 5

Motor Testing of the Peripheral Nerves of the Upper Extremity (Table 43-1 page 292)
Adduction/abduction of digits

Answer 5

Ulnar nerve

Question 6

Tendon which splits and inserts at the PIP joint

Examined by holding all other digits in extension and flexing the PIP joint against resistance

Answer 6

Flexor Digitorum Superficialis

Question 7

Tendon runs below the FDS past the split to attach at the DIP joint
Examined by holding PIP joint in extension and flexing the DIP joint against resistance

Answer 7

Flexor Digitorum Profundus

Question 8

Tendon that can be assessed by sequentially flexing the digit at the MCP, PIP, and DIP joints and having the patient extend the digit

Answer 8

Extensor Digitorum

Question 9

Sensory Testing of Peripheral Nerves in the Upper Extremity (Table 43-2 page 292)
First dorsal web space

Answer 9

Radial nerve

Question 10

Sensory Testing of Peripheral Nerves in the Upper Extremity (Table 43-2 page 292)
Volar tip of index finger

Answer 10

Median nerve

Question 11

Sensory Testing of Peripheral Nerves in the Upper Extremity (Table 43-2 page 292)
Volar tip of little finger

Answer 11

Ulnar nerve

Question 12

Normal two-point discrimination is defined as —?—mm

Answer 12

<6 mm

Good: 6 to 10 mm
Fair: 11 to 15 mm
Poor: >15 mm

Question 13

The two most important areas to maintain sensation to preserve pinch sensation

Answer 13

Ulnar side of the distal thumb & the radial side of the index volar pad

Question 14

Test performed to better assess the integrity of the radial and ulnar arteries

Answer 14

Allen test

The test is performed by first instructing the patient to make a fist as tightly as possible. Then, apply digital pressure to both the radial and ulnar artery at the volar aspect of the wrist. Next, while maintaining compression of the radial and ulnar artery, have the patient open the hand—a blanched palm indicates that arterial inflow is occluded. Now release the radial artery and note the time for the hand to return to normal color.

Question 15

In Allen test, refill times of —?— seconds raise suspicion for a significant vascular injury

Answer 15

> 3 seconds

Question 16

Use to assess the vascular integrity of an injured arm or leg by the ratio of the systolic blood pressure between the injured and the uninjured side

Answer 16

Arterial pressure index

Question 17

Is used to exsanguinate the limb and prevent backflow bleeding

Answer 17

Esmarch’s technique

Elevate the injured extremity and apply an elastic bandage starting distally and wrapping proximally to the area where the cuff will be applied. The cuff is applied around the upper arm and inflated to pressures above the systolic blood pressure of the patient, but not to exceed 250 mm Hg (33 kPa). The cuff tubing is clamped with a hemostat instead of closing the air release valve to prevent slow air leakage. The maximum cuff inflation time is limited to 30 minutes to avoid ischemic damage to the distal muscles and nerves.

Question 18

Can be done to determine extension of injury into the joint capsule

Answer 18

Saline Load Test

Question 19

TRUE or FALSE?

No advantage of adding methylene blue to the injected saline in saline load test

Answer 19

TRUE

There is no advantage of adding methylene blue to the injected saline in saline load test, and it may affect operative management by staining the intra-articular surfaces.

Question 20

Uncomplicated hand lacerations are those that —?—

Answer 20

(1) Not caused by a human or animal bite
(2) Not complicated by a fracture through bone or a joint
(3) Not involve tendons, bones, large vessels, or nerves
(4) No severe soft tissue damage or maceration

Question 21

Major issues in upper arm & elbow lacerations

Answer 21

(1) Arterial laceration
(2) Nerve laceration
(3) Elbow joint penetration

Question 22

Most common bacterial species isolated from human bite wounds

Answer 22

Staphylococcus aureus

Question 23

Inability to extend the DIP joint, resulting in the joint being held in flexion

Answer 23

Mallet finger deformity

Question 24

Hyperextension of the proximal interphalangeal joint resulting from unrepaired mallet finger deformity, caused by the complete disruption of the terminal extensor mechanism and subsequent proximal and dorsal displacement of the lateral bands

Answer 24

Swan neck deformity

Question 25

Hyperflexion of the PIP joint with hyperextension of the DIP joint

Answer 25

Boutonniere deformity

Question 26

The strongest contraindications to replantation of amputated digit

Answer 26

Crush & avulsion injuries

Question 27

Suspected when static two-point discrimination is distinctly greater on one side of the volar pad than the other, or when it is >10 mm

Answer 27

Digital nerve injuries

Question 28

TRUE or FALSE?
Skin grafting is successful in digital tip injury with even with a significant loss of tissue at the fingertip exposes the distal phalanx tuft

Answer 28

FALSE

Skin grafting will be unsuccessful if a significant loss of tissue at the fingertip exposes the distal phalanx tuft, as bone does not provide adequate vascularity to support donor tissue

Question 29

Digital tip amputations defined by the retention of the neurovascular bundle as well as portions of the underlying bone

Answer 29

Incomplete digital tip amputations

Question 30

TRUE or FALSE?

Replantation of a complete amputation distal to the lunula is not usually advocated for adults

Answer 30

TRUE

Replantation of a complete amputation distal to the lunula is not usually advocated for adults because the procedure is technically demanding and has a generally poor prognosis

Question 31

Structure made by the nail, nail bed, and surrounding soft tissue

Answer 31

Perionychium

Question 32

Nail structure made up of the germinal and sterile matrices

Answer 32

Nail bed

Question 33

Begins at the proximal base of the nail (typically 3 to 5 mm proximal to the eponychium) and extends to the lunula

Answer 33

Germinal matrix

Question 34

Most common nail injury due to closure of the fingertip in a door and is usually located at the distal portion of the nail bed

Answer 34

Injury to the perionychium

Question 35

TRUE or FALSE?
Simple trephination produces a good to excellent outcome depending on the subungual hematoma size, injury mechanism, or the presence of fracture

Answer 35

FALSE

Simple trephination produces a good to excellent outcome in most patients regardless of subungual hematoma size, injury mechanism, or the presence of fracture.

Question 36

Nail removal in nail bed injuries is recommended only if with —?—

Answer 36

Partial nail avulsion OR surrounding nail fold disruption