Wrist & Hand: Anatomy, biomechanics, pathology.

Question 1

What bones form the proximal and distal radiocarpal joint surfaces? Comment on concavity/convexity of each surface.

Answer 1

proximally: radius & radioulnar disc - concave
distally: scaphoid, lunate, and triquetrum - convex

Question 2

What bones form the proximal and distal midcarpal joint surfaces? Comment on the concavity/convexity of each surface.

Answer 2

proximally: scaphoid, lunate, and triquetrum
distally: trapezium, trapezoid, capitate and hamate
It has a reciprocal concave-convex configuration.

Question 3

How do you divide the wrist into 4 functional groups?

Answer 3

1. Trapezium
2. Scaphoid
3. Capitate, Hamate, Trapezoid
4. Lunate, Triquetrum

Question 4

Using the groups here, what group(s) move on what group(s) when moving from full wrist flexion to neutral? From neutral to full extension?

1. Trapezium
2. Scaphoid
3. Capitate, Hamate, Trapezoid
4. Lunate, Triquetrum

Answer 4

Full Flexion to Neutral:
#3 moves on rows #2 and #4 until the hand is in line with the forearm. #3 & #2 in CPP at this time.
Neutral to Full Extension:
#3 & #2 move as a unit on #4 while #4 and #2 move on radius and ulnar disc.
#1 with thumb always loose packed throughout range. Fanning of hand occurs in extension and reverse for flexion due to conjuct rotations.

Question 5

What is the closed pack position of the radiocarpal joint? For intercarpal joint? Why is this relevant to us?

Answer 5

Radiocarpal CPP: Full Extension
Intercarpal CPP: Neutral
Stability testing of this joint therefore in full extension
Stability of intercarpal joints in neutral
Mobility testing/mobs in full flexion (IC) or neutral (RC).

Question 6

What are the 2 main types of distal radial fractures?

Answer 6

Colles Fracture: Dorsal/Extension displacement

Smith’s Fracture: Volar(Palmar)/Flexion displacement

Question 7

What is the most frequently dislocated carpal bone? What is typical treatment for this?

Answer 7

Lunate. Treatment is usually reduction by MD then splint in flexion for 3 weeks with no extension allowed for 5-6 weeks.

Question 8

What is a perilunate dislocation? What test is performed to dx this?

Answer 8

Tearing of the ligaments between the triquetrum and the lunate. The Ballotment test (fwd and bwk displacement of lunate and triquetrum from each other resulting in pain is a + test.)

Question 9

What is Keinbock’s disease?

Answer 9

Spontaneous avascular necrosis of the lunate

Question 10

What is the most commonly fractured carpal bone? What are 5 tests to distinguish a fracture of this bone?

Answer 10

Scaphoid

1. Axial compression along index and middle fingers which press directly on the scaphoid.
2. Percussion at the top of the thumb.
3. Forced DF of the hand.
4. Active pronation of the hand against resistance.
5. Scaphoid fracture test: pronation and ulnar deviation. + is pain in snuffbox.

Question 11

1. What is a prime cause of distal radio-ulnar fibrocartilaginous disc injury?
2. What is a prime cause of scaphoid impaction syndrome?
3. Prime cause of radial styloid impingement syndrome?

Answer 11

1. Forced or loaded supination and pronation.
2. Repetitive compressive impacts during developmental years (like gymnasts).
3. Repetitive forced radial deviation (golfers often).

Question 12

What is gamekeepers thumb?

Answer 12

ulnar collateral ligament sprain. Read more on pg. 142 if interested.

Question 13

1. What nerve does carpal tunnel syndrome involve?

2. What is the first signs? What can it lead to?

Answer 13

1. median nerve.

2. sensory disturbances leading to motor disturbances/atrophy.

Question 14

What are 4 clinical tests for carpal tunnel?

Answer 14

1. Phalen’s test
2. Tinel’s test for the wrist
3. Median Nerve Compression test
4. Sensory & motor testing

Question 15

What are possible treatments for carpal tunnel syndrome?

Answer 15

Conservative: NSAIDS, splinting in neutral or slight extension, rest.
Surgery if conservative fails or it is really severe.

Question 16

What nerve passes through Guyon’s Canal? What are the signs and symptoms if this nerve becomes entrapped in the canal?

Answer 16

The ulnar nerve, causing altered sensation in the area of the little finger and later atrophy of hypothenar eminence and other medial hand. muscles.

Question 17

What are 3 clinical tests for ulnar nerve entrapment?

Answer 17

1. Froment’s Sign
2. Interossei resisted test
3. Isolated little finger abduction

Question 18

1. What is DeQuervain’s Tenosynovitis?
2. Signs & Symptoms (4 possible)?
3. Tx (lots of things)?

Answer 18

1. Stenosis in tendon sheath of abductor pollicus longus and extensor pollicus brevis caused by repetitive injury.
2. Pain in tendons of snuffbox, + Finkelstein’s Test, pain in resisted radial deviation, and crepitus.
3. TFM, modalities, rest, stretching, cortisone, etc.