Chapter 70 - Functional Anatomy And Principles Of Upper Extremity Surgery

Question 1

The CMC joints

Answer 1

• The mobility of the CMC joints of the index through small fingers increases toward the ulnar aspect of the hand
• Angulated fractures are better tolerated in the ulnar digits because of compensatory motion

Question 2

The MCP joints

Answer 2

• Have little tolerance for stiffness coz arc of motion of fingers starts at MCP joints

Question 3

The PIP and DIP joints

Answer 3

• Stiffness is better tolerated
• Particularly DIP joint, STABILITY is more important than MOBILITY
• Rotational and angular deformity are not tolerated coz the may lead to scissoring of the fingers

Question 4

The forces acting on hand joints

Answer 4

• Includes:

1- static constraints (collateral ligaments, joint capsules, volar plate)

2- tendons (create dynamic compression through movement)

Question 5

Swan-neck deformity

Answer 5

• Volar plate disruption during dorsal dislocation of PIP
• Lat bands may subluxate dorsally over time
• Hyperextension of PIP
• Flexion of DIP

Question 6

Boutonnière deformity

Answer 6

• Disruption of central slip of dorsal middle phalanx and triangular ligament
• lat bands subluxate volarly
• Flexion of PIP
• Hyperextension of DIP

Question 7

Wrist

Answer 7

• Normal flex/ext => 90/70 deg

- Arc => 80 deg

Question 8

Distal Radioulnar Joint

Answer 8

• Ulna has no direct contact with carpal bones

- Ulna connected to radius by triangular fibrocartilage complex

Question 9

The Radiocarpal joint

Answer 9

• 80% of the forces through the arm are dispersed by the carpal articulation with radius
• Tough, strong volar capsular ligament
• Less stout dorsal capaular ligament

Question 10

Dorsal Intercalated Segment Instability

Answer 10

• Dorsal tilt occurs when the scapholunate ligament is torn coz the scaphoid flexes and the lunate must extend with the triquetrium

Question 11

Volar Intercalated Segment Instability

Answer 11

• Occurs when the lunotriquetrial ligament is disrupted, leaving the scapholunate ligament intact, resulting in flexion of lunate with scaphoid

Question 12

Acute injuries

Answer 12

• Life over limb
• Attempting to “tie off” a bleeding vessel is not recommended
• Elevation and direct pressure is sufficient to stop bleeding

Question 13

Injuries that require urgent operative intervention

Answer 13

• Limb-threatening ischemia
• Most open fractures
• Pressure injection injuries
• Active bleeding in the setting of coagulopathy

Question 14

For amputated digits

Answer 14

• Hypothermia (wrapped in moist gauze inside plastic bag placed on ice) reduce the metabolic by-product that damage the tissue

Question 15

Autonomous sensory zone of Radial, Median and Ulnar nerves

Answer 15

• Radial n. => first dorsal web space
• Median n. => volar aspect of index fingertip
• Ulnar n. => volar tip of the small fingertip

Question 16

Intrinsic positioning of the hand

Answer 16

• Wrist in slight extension
• MCP in near full flexion
• IP in full extension

Question 17

Reconstructive Principles in Upper Limb

Answer 17

1- Restore circulation
2- Obtain soft tissue coverage
3- Align and stabilize bony anatomy
4- Restore nerve function
5- Mobilize joints
6- Restore tendon function

Question 18

Use of antibiotics

Answer 18

• Indicated in procedures involving implants or bony work and those lasting > 2 hr
• Abc redosed during surgery depending on the half life properties of the drug

Question 19

Tourniquet

Answer 19

• 100 mmHg above the systolic BP is sufficient
• Tourniquet time up to 90 min
• Anything over 90-120 min, increases the risk of reperfusion injury
• Arm tor. => elbow, forearm and wrist
• Forearm tor. => hand and digits

Question 20

Incisions in hand

Answer 20

• Should not cross the flexion crease
• Longitudinal incision for dorsum of hand (coz have thinner and more mobile skin)
• Zigzag incision for volar aspect of palm and fingers

Question 21

Bruner incision

Answer 21

• Diagonal incisions between flexion creases that serve to create a series of short broad-based flaps

Question 22

Closure of hand incisions

Answer 22

• Single layer interrupted nylon suture

- If a laceration crosses skin crease, a Z-plasty is considered

Question 23

Dressing of wounds

Answer 23

• Non-occlusive yet adherent (petroleum impregnated gauze)
• Dry gauze or fluffy
• Circumferential dressing applied loosely
• Splint immobilisation
• Elevation of the hand