Clinical Conditions of the Wrist Joint

Question 1

What is a Colles’ fracture?

Answer 1

An extra-articular fracture of the distal radial metaphysis, with dorsal angulation and impaction. An associated ulnar styloid fracture is present in up to 50% of cases.

Question 2

Which types of patients are more prone to getting a Colles’ fracture?

Answer 2

They are particularly common in patients with osteoporosis (reduced bone density), and as such they are most frequently seen in post-menopausal women. Younger patients who present with a Colles’ fracture have usually been involved in high impact trauma, e.g. skiing.

Question 3

What is the mechanism of injury in a Colles’ fracture?

Answer 3

The mechanism of injury is usually a fall onto an outstretched hand (FOOSH) with a pronated forearm and wrist in dorsiflexion. The energy is transmitted from the carpus to the distal radius in a dorsal direction and along the long axis of the radius. The fracture is therefore dorsally angulated and impacted. The patient will present with a painful, deformed, swollen wrist.

Question 4

How are most Colles’ fractures treated?

Answer 4

Most Colles’ fractures can be treated by reduction and immobilisation in a cast

Question 5

What are the complications associated with a Colles’ fracture?

Answer 5

• Malunion leading to a dinner fork deformity
• Median nerve palsy and post-traumatic carpal tunnel syndrome
• Secondary osteoarthritis (more common with intra-articular fractures)
• Tear of the extensor pollicis longus tendon (by attrition of tendon over a sharp fragment of bone)

Question 6

What is a Smith fracture?

Answer 6

Smith fractures are fractures of the distal radius with palmar angulation of the distal fracture fragments. 85% are extra-articular, so a smith fracture can usually be thought of as a reverse Colles’ fracture.

Question 7

Which type of patients are more prone to getting a Smith fracture?

Answer 7

They typically occur in young males and elderly females.

Question 8

What is the typical mechanism of injury in a Smith fracture?

Answer 8

A fall onto a flexed wrist or a direct blow to the back of the wrist

Question 9

What is garden spade deformity?

Answer 9

Malunion of a Smith fracture, with residual palmar displacement of the distal radius results in a cosmetic deformity called garden spade deformity. The garden spade deformity narrows and distorts the carpal tunnel and can result in carpal tunnel syndrome.

Question 10

What is carpal tunnel syndrome?

Answer 10

Compression of the median nerve as it passes through the carpal tunnel from the forearm into the hand.

Question 11

What are the risk factors for carpal tunnel syndrome?

Answer 11

Obesity 
Repetitive wrist work 
Pregnancy 
Rheumatoid arthritis 
Hypothyroidism

Question 12

What can the nerve compression result in?

Answer 12

Nerve compression may result in ischaemia, focal demyelination, decrease in axonal calibre and eventually axonal loss.

Question 13

Where will a patient with carpal tunnel syndrome experience paraesthesia?

Answer 13

In the distribution of the median nerve: thumb, index finger, middle finger and radial half of ring finger

Question 14

Why are symptoms of carpal tunnel syndrome often worse at night?

Answer 14

The wrist drifts into flexion during sleep, narrowing the carpal tunnel further.

Question 15

Why is sensation to the palm spared in carpal tunnel syndrome?

Answer 15

The palmar cutaneous branch of the median nerve branches proximal to the carpal tunnel and passes superficial to it into the palm so it isn’t compressed.

Question 16

Why can long-standing carpal tunnel syndrome result in muscle weakness and atrophy of the thenar muscles?

Answer 16

The motor branch of the median nerve to the thenar muscles exits the median nerve distal to the carpal tunnel. Hence long-standing carpal tunnel syndrome can result in muscle weakness and atrophy of the thenar muscles (flexor pollicis brevis (superficial head), opponens pollicis, abductor pollicis brevis). The patient will still be able to flex their thumb as flexor pollicis longus is innervated by the anterior interosseous branch of the median nerve in the forearm, and the deep head of the flexor pollicis brevis is innervated by the ulnar nerve. Adduction of the thumb is also spared as adductor pollicis is supplied by the ulnar nerve.

Question 17

What is the result of motor and sensory disturbance from carpal tunnel syndrome in everyday life?

Answer 17

Due to the motor and sensory disturbance, manual dexterity is diminished and difficulty with daily activities such as buttoning clothes, picking up small objects is often encountered. Pain can also occur proximally in the forearm, elbow, shoulder and neck.

Question 18

What is Ulnar nerve compression in Guyon’s canal? (a.k.a. Guyon’s canal syndrome)

Answer 18

The ulnar nerve can be compressed in Guyon’s canal, as it passes lateral to the pisiform bone over the palmar surface of the flexor retinaculum.

Question 19

Where does the patient report paraesthesia?

Answer 19

In the ring and little fingers, progressing to weakness of the intrinsic muscles of the hand supplied by the ulnar nerve (adductor pollicis, palmar and dorsal interossei, and the lumbricals to the ring and little fingers and deep head of the flexor pollicis brevis)