Trauma and orthopaedics (7): The hand

Question 1

hand can be split up into the

Answer 1

phalanges

metacarpals

carpals

Question 2

Carpal bones

Answer 2

• 8 irregularly shaped bones ‘Some Lovers Try Positions That They Can’t Handle’
• Organised into two rows

Question 3

metacarpal bones

Answer 3

• Articulates proximally with the carpals and distally with the proximal phalanges
• Numbered and associated with a digit:
  
  • Metacarpal I – Thumb.
  • Metacarpal II – Index finger.
  • Metacarpal III – Middle finger.
  • Metacarpal IV – Ring finger.
  • Metacarpal V – Little finger.

Question 4

phalanges

Answer 4

• Thumb has a proximal and distal phalanx
• Rest of digits have proximal, middle and distal phalanges

Question 5

the wrist joint also known as

Answer 5

• Radiocarpal joint
• Synovial joint
• Ellipsoidal- allowing movement along two axes
  
  • Flexion
  • Extension
  • Adduction
  • Abduction
• Articulating surfaces
  
  • Distally- proximal row of the carap bones
  • Proximally- distal end of the radius and

Question 6

the ……. is not part of radiocarpal (wrist joint)

Answer 6

• Ulnar is not part of the wrist joint
  
  • Articulates with the radius just proximal to the wrist joint at the distal radioulnar joint
  • Prevented from articulating with carpal bones by fibrocartilaginous ligament called the articular disc

Question 7

stabilising factors of the wrist joint

Answer 7

Stabilising factors

• Joint capsule
• Ligaments

Question 8

joint capsule

Answer 8

Dual layered capsule

• Fibrous outer layer attaches to the radius, ulnar and the proximal row of the carpal bones
• Internal layer comprises a synovial membrane secretes synovial fluid which lubricates the joint

Question 9

innervation of the wrist

Answer 9

• Median nerve- anterior interosseous branch
• Radial nerve- posterior interosseous branch
• Ulnar nerve- deep and dorsal branches

Question 10

muscle compartment

Answer 10

Can be divided into extrinsic and intrinsic muscles:

• Extrinsic
  
  • Located in anterior and posterior compartments of the forearm
  • Responsible for crude movements and produce a forceful grip
• Intrinsic
  
  • Located within the hand itself
  • Responsible for fine motor functions of the hand
• No muscles on the dorsal (only palmar) part of the hand

Question 11

intrinsic muscles of the hand

Answer 11

thenar (median nerve)- thumb

hypothenar (little finger)

a number of muscles within these but dont worry about them

Question 12

Lumbrical muscles

Answer 12

• 4 lumbricals in the hand
• Each associated with a finger
• Link the extensor tendons to the flexor tendons
• Denervation of theses muscles is the basis for the ulnar claw and hand of benediction

Question 13

interosseus muscles

Answer 13

Located between the metacarpals- divided into two groups: Dorsal and Palmar

• Dorsal interossei X4

Most superficial of all dorsal muscles

• Action
  
  • Abduct the fingers at the MCP joint
  • Attachment
    
    • Originates – each come from the lateral and medial surfaces of the metacarpals.
    • Inserts- into the extensor hood and proximal phalnx of each finger
  • Blood supply
  • Innervation
    
    • Ulnar
• Palmar interossei X3
  
  • Action
    
    • Adducts the fingers at the MCP joint
  • Attachment
    
    • Originates from a medial or lateral surface of a metacarpal
    • Inserts into the extensor hood and proximal phalanz of same finger
  • Blood supply
  • Innervation
    
    • Ulnar nerve

Question 14

areas in the hand

Answer 14

anatomical snuffbox

Triangular depression found on the lateral aspect of the dorsum of the hand, located at the level of carpal bones  best seen when thumb is extended

• In past the depression was used to hold snuff (ground tobacco) before inhaling via the nose

Question 15

borders of the anatomical snuffbox

Answer 15

Snuffbox has 3 borders, a floor and a roof:

• Ulnar (medial) border: tendon of the extensor pollicis longus
• Radial (lateral) border: tendons for the extensor pollicis brevis and abductor pollicis longus
• Proximal border: styloid process of the radius
• Floor: scaphoid
• Roof: skin

Question 16

Contents of the anatomical snuffbox

Answer 16

• Radial artery
  
  • Crosses the floor of the anatomical snuffbox, then turns medially and travels between the head of the adductor pollicis muscle
  • Radial pulse can be palpated
• Superficial branch of the radial nerve
  
  • Found in the skin and subcutaneous tissue of the anatomical snuff box- innervates the dorsal surface of the lateral three and half digits, and the associated area on the back of the hand
• Cephalic vein

Question 17

innervation of the hand

Answer 17

Question 18

trigger finger

Answer 18

Trigger finger is a condition causing pain and difficulty moving a finger. It is also known as stenosing tenosynovitis.

• finger or thumbs gets lock when in flexion, prevnting a return to extension

Question 19

pathophysiology of trigger finger

Answer 19

The flexor tendons of the fingers pass through several tunnels (sheaths) along the length of the fingers. In trigger finger, there is thickening of the tendon or tightening of the sheath. This prevents the tendon from smoothly moving through the sheath when the finger is flexed and extended, causing pain, stiffness, or catching symptoms.

The most commonly affected part of the sheath is the first annular pulley (A1) at the metacarpophalangeal (MCP) joint.

There may be a nodule on the tendon. When the finger is flexed, the nodule is outside the A1 pulley. As the finger is extended from a flexed position, the tendon nodule can get stuck at the entrance to the A1 pulley. This causes the finger to lock or get stuck in the bent position. It may release suddenly with a painful pop or click.

Question 20

which conditions is trigger finger associated with

Answer 20

rheumatoid arthritis, amyloidosis, and diabetes mellitus.

Question 21

pathophysiology of trigger finger

Answer 21

Most cases of trigger finger are preceded by flexor tenosynovitis, often from repetitive movements, leading to inflammation of the tendon and sheath.

Superficial and deep flexor tendons with local tenosynovitis at the metacarpal head subsequently develop localised nodal formation on the tendon, distal to the pulley . The A1 pulley is the most frequently involved ligament in trigger finger.

When the fingers are flexed, the node moves proximal to the pulley, however when the patient attempts to extend the digit this node fails to pass back under the pulley. Consequently, the digit becomes locked in a flexed position.

Question 22

which pulley is most frequently invovled ligament in trigger finger

Answer 22

A1 pulley

Question 23

RF for trigger gingrr

Answer 23

• In their 40s or 50s
• Women (more often than men)
• People with diabetes (more with type 1, but also type 2)

Question 24

presentation of trigger finger

Answer 24

The typical presentation is with a troublesome finger, that:

• Is painful and tender (usually around the MCP joint on the palm-side of the hand)
• Does not move smoothly
• Makes a popping or clicking sound
• Gets stuck in a flexed position

typically worse in morning

Question 25

diagnosis of trigger fingers

Answer 25

clinical

Question 26

management of trigger finger

Answer 26

* Rest and analgesia (a small number resolve spontaneously) * Splinting * Steroid injections * Surgery to release the A1 pulley *

Question 27

management of trigger finger

Answer 27

conservative * Rest and analgesia (a small number resolve spontaneously) * Splinting other options * Steroid injections * Surgery to release the A1 pulley

Question 28

dupuytrens contracture

Answer 28

Dupuytren’s contracture is a condition where the fascia of the hand becomes thickened and tight, leading to finger contractures. -the finger is tightened into a flexed position and cannot fully extend.

Question 29

pathophysiology of duputryens contracture

Answer 29

palmar fascia ## Footnote of the hands becomes thicker and tighter and develops nodules. Cords of dense connective tissue can extend into the fingers, pulling the fingers into flexion and restricting their ability to extend (***contracture***). It is unclear why the fascia becomes thicker and tighter. However, it is thought to be an inflammatory process in response to microtrauma.

Question 30

RF for dupuytrens

Answer 30

* Age * Family history (autosomal dominant pattern) * Male * Manual labour, particularly with vibrating tools * Diabetes (more with type 1, but also type 2) * Epilepsy * Smoking and alcohol

Question 31

presentation of dupuytrens

Answer 31

* first sign: hard nodules on pal * flexion of finger into area of thickened fascia * impossible to extend affected finger fully * **ring finger** most common * no pain

Question 32

special test fo dupuytens

Answer 32

The ***table-top test*** is a straightforward test for Dupuytren’s contracture. The patient tries to position their hands flat on a table. If the hand cannot rest completely flat, the test is positive, indicating Dupuytren’s contracture.

Question 33

conservative management of dupuytrens

Answer 33

* hand therapy * injectable collagenase clostridium histolyticum (CCM) * for early presentation

Question 34

surgical management of dupuytrens

Answer 34

indication: functional impairment, MCP joint contraction \>30 degrees any PIP contracture involves excision of diseased fascia (fasciectomy)

Question 35

surgical management of dupuytrens

Answer 35

indication: functional impairment, MCP joint contraction \>30 degrees any PIP contracture involves excision of diseased fascia (fasciectomy)

Question 36

types of fasciectomy for dupuytrens

Answer 36

* **Regional fasciectomy**, whereby the entire cord is removed (the most common approach) * **Segmental fasciectomy**, whereby only short segments of the cord are removed * **Dermofasciectomy**, whereby the cord and overlying skin are removed, to be followed by a skin graft

Question 36

types of fasciectomy for dupuytrens

Answer 36

* **Regional fasciectomy**, whereby the entire cord is removed (the most common approach) * **Segmental fasciectomy**, whereby only short segments of the cord are removed * **Dermofasciectomy**, whereby the cord and overlying skin are removed, to be followed by a skin graft

Question 37

scaphoid fracture

Answer 37

The **scaphoid** is ‘boat’-shaped\* bone and is the **most common carpus** to be fractured. * diagnostic uncertainty therefore often referred to orthopaedics

Question 38

RF for scaphoid fracture

Answer 38

men aged 20-30 years high energy impact

Question 39

blood supply to the scaphoid

Answer 39

**radial artery** The scaphoid is anatomically **divided into three parts**: the proximal pole, waist, and distal pole. * **dorsal** branch supplies 80% of the scaphoid, entering via the distal pol and travels in a retrograde fashion towards the proximal pole * **volar** branch supplies the rest

Question 40

scaphoid at risk of

Answer 40

AVN fractures can **compromise the blood supply**, leading to avascular necrosis (AVN) and subsequent degenerative wrist disease. **The more proximal the scaphoid fracture, the higher the risk of AVN.**

Question 41

presentation of scaphoid fracture

Answer 41

* high energy trauma * sudden onset wrist pain * tenderness on the **floor of the anatomical snuffbox** * pain on palpating scaphoid tubercle * pain on telescoping of thumb

Question 42

investigations for scaphoid fracture

Answer 42

‘scaphoid series’ of x-ray (AP, lateral and oblique views) BEWARE not always detected by initial x-ray- may need to repeat in 10-14 days (immobilise wrist and thumb splint in mean time)

Question 43

which other bones at risk of AVN

Answer 43

* scaphoid * head of femur * knee * talus

Question 44

management of scaphoid fracture if undisplaced

Answer 44

**strict immobilisation** in a plaster with a thumb spica splint. **However**, undisplaced fractures of the **proximal** pole have a high risk of AVN and surgical treatment may be advocated, particularly if it is the dominant hand of a working-age patient.

Question 45

management of scaphoid fracture if displaced

Answer 45

**All displaced fractures** should be **fixed operatively**. The most common operative technique is using a **percutaneous variable-pitched screw**, which can be placed across the fracture site to compress it.