Flashcards in Orthopaedics - Hand, wrist and elbow Deck (70)
What is the most common fracture in children? What is the main complication?
Supracondylar fracture is the most common fracture of children with a peak incidence between the ages of 5-7.
Depending on their exact type they may compromise brachial artery, median (typically anterior interosseus branch), radial or ulnar nerve function so check neurovascular status. Keeping the elbow in extension after injury prevents exacerbating brachial artery damage from the time of injury.
How should supracondylar fractures be managed?
Avoid flexing the elbow to >90 degrees. The exact management depends on the type of fracture as outlined in the Gartland classification system:
Type I fractures = non displaced fractures and can be managed by a cast and sling
Type II fractures = may require reduction under GA
Type III fractures = require surgery
Management is also determined by whether there is condylar involvement. Fracture of the medial epicondyle may require surgery if there are bone fragments in the joint or ulnar nerve compression symtpoms. Lateral epicondylar fractures can lead to cubitus valgus and ulnar nerve palsy. T shaped intercondylar fractures are supracondylar fractures with a break between the condyles.
What are the radiological findings of elbow fracture?
The two most common findings seen on x-ray are the "anterior sail sign" or the "posterior fat pad sign".
The anterior fat pad sign can be seen on a lateral elbow x-ray as a radiolucent triangle in front of the distal humerus. It can be present in a normal elbow and is only abnormal if it is raised off the bone by an effusion.
A visible posterior fat pad is always abnormal. The abscence of either of these signs makes a fracture very unlikely.
Note that elbow fracture is not the same as supracondylar fracture which involves the distal humerus.
How should elbow fractures be managed?
If there is no obvious fracture on imaging (remember to get at least 2 views), but if an effusion is present treat initially with a broad arm sling. Re x-ray after 10 days (the fracture will be easier to see as the effusion subsides). If the x-ray is clear then start mobilisation. If it is fractured then internal fixation may be required.
Physio and mobilisation are important in preventing stiffness.
What causes fractures of the radial head?
Fractures to the radial head often occur following a fall onto an outstretched hand. The elbow is painful, swollen and tender over the radial head.
There may be normal flexion and extension, but supination and pronation may be painful.
How are radial head fractures classified?
1) Undisplaced fractures - these are difficult to see on plain film x ray so associated features are used to identify the fractures (e.g. posterior fat pad seen as an area of lucency at the posterior aspect of the distal humerus is abnormal and indicates a joint effusion). If no further fractures are seen and the clinical signs and symptoms are suggestive then an undisplaced radial head fracture can be diagnosed. These are usually managed with analgesia and a sling
2) Displaced fractures - the radial head should align with the capitulum of the humerus. If there is a fracture and displacement of the head this is called a displaced fracture. These fractures should be corrected with internal fixation to minimise the risk of painful pronation and supination
3) Comminuted fractures - this is where the radial head is fractured in 2 places. These are managed according to severity
How many radial head fractures are associated with the "terrible triad" and what is it?
3-14% are associated with (i) fracture, (ii) elbow dislocation, and (iii) coronoid process fracture.
This is important, because it can result in joint instability and post traumatic complications. Radial nerve injury may occur with severe anterior displacement but it is rare.
What is meant by the term "pulled elbow"? How can it be corrected?
This refers to a situation where the radial head slips out of the annular ligament. Typically a patient aged 1-4 is lifted by the arms forcefully during play. The patient holds the arm slightly flexed and twisted inwards.
Reduction is achieved by cradling the elbow with thumb and forefingers over the radial head and either hyperpronating or supinating and flexing the elbow.
Imaging is not needed, but it can recur in 25% of cases.
What causes an elbow dislocation?
This can be caused by a fall onto and as yet not fully outstretched hand, with the elbow flexed. The impact causes posterior ulnar displacement on the humerus and a swollen elbow fixed in flexion.
Damage to the brachial artery and median nerve are rare but check for neurovascular status.
What separates the forearm into distinct compartments?
2 structures separate the forearm into an anterior (flexor) and a posterior (extensor) compartment. This is the interosseous membrane and the deep fascia. This is continuous with the fascia of the arm and is firmly attached to the periosteum of the subcutaneous border of the ulna.
The idea of compartments is important, because each compartment receives its own blood and nerve supply. Generally, veins are located in the subcutaneous tissue above the arteries and deeper nerves.
How are the muscles of the anterior compartment separated?
All the muscles of the anterior compartment are forearm flexors. They are divided into superficial, intermediate and deep muscles.
All the superficial muscles and the ulnar head of flexor digitorum superficialis (an intermediate muscle) arise from the common flexor tendon which is located on the medial epicondyle of the humerus.
Superficial flexors are: pronator teres, flexor carpi radialis, palmaris longus and flexor carpi ulnaris. Brachioradialis is also a superficial muscle but originates on the lateral supracondylar ridge of the humerus and is actually an extensor!
Flexor digitorum superficialis is the only member of the intermediate group.
Deep flexors: flexor digitorum profundus, flexor policis longus and pronator quadratus.
Which 2 muscles in the anterior forearm have duel innervation?
Most of the muscles in the anterior forearm compartment are innervated by the median nerve with the exception of flexor carpi ulnaris and the ulnar half of flexor digitorum profundus which are innervated by the ulnar nerve.
Describe the course of the ulnar nerve in the forearm?
The ulnar nerve enters the forearm by passing behind the median epicondyle of the humerus and entering the cubital tunnel. When it emerges it passes between the 2 heads of flexor carpi ulnaris (which it supplies) and continues distally towards the wrist.
The ulnar nerve also supplies half of flexor digitorum profundus. In the lower forearm, the ulnar nerve lies medial to the ulnar artery and the tendon of flexor carpi ulnaris. Here it gives of a dorsal superficial branch to supply the backs of the medial 1.5 digits.
It enters the wrist superficial to the flexor retinaculum and divides into its terminal branches.
What re the terminal branches of the ulnar nerve?
These are superficial branch supplying the skin of the medial 1.5 digits and a deep branch supplying:
- hypothenar muscles (flexor digiti minimi, abductor digiti minimi, opponens digiti minimi)
- medial 2 lumbricals
- all the interossei
- adductor pollicis
What is the blood supply to the anterior forearm compartment?
Ulnar artery and its anterior interosseous branch; radial artery.
What is the arrangement of the forearm extensor muscles?
The extensor muscles are located in the posterior forearm compartment. Brachioradialis and extensor carpi radialis longus originate from the lateral supracondylar ridge of the humerus.
The other muscles considered in superficial and deep layers which are both innervated by the posterior interosseous branch of the radial nerve. The superficial muscles originate from the common extensor tendon located on the lateral epicondyle of the humerus. The muscles of the deep layer arise from the back of the radius, ulna and interosseous membranes.
What is the neurovascular supply to the posterior compartment of the forearm?
The posterior interosseous artery (branch of the common interosseous artery) and posterior interosseous nerve (branch of the radial nerve) supply the posterior compartment of the arm.
Describe the course of the radial nerve in the arm and forearm?
The radial nerve arises as a continuation of the posterior cord of the brachial plexus. In the arm it runs with profunda brachii artery between the long and medial heads of triceps into the posterior compartment and carries on down between the two heads. At the midpoint of the arm it enters the anterior compartment by piercing the lateral intermuscular septum. In the region of the lateral epicondyle the radial nerve lies under the cover of brachioradialis and divides into the superficial radial and posterior interosseous nerves.
The radial nerve innervates all of the arm extensors.
Describe the course of the median nerve in the upper limb?
The median nerve initially lies lateral to the brachial artery but crosses it medially in the mid arm. In the cubital fossa, the median nerve lies medial to the brachial artery which itself lies medial to the biceps tendon. The median nerve then passes deep to the bicipital aponeurosis before passing between the two heads of pronator teres. A short distance below this, the anterior interosseous branch is given off. This descends with the anterior interosseous artery to supply the deep flexor muscles of the forearm with the exception of the ulnar half of flexor digitorum superficialis.
In the forearm, the median nerve lies between flexor digitorum superficialis and flexor digitorum profundus. A short distance above the wrist it emerges from the lateral side of flexor digitorum superficialis and gives off the palmar cutaneous branch. In then enters the hand through the carpal tunnel together with 9 tendons (4 from flexor digitorum superficialis, 4 from flexor digitorum profundus and 1 from flexor pollicis longus).
What is the carpal tunnel? What forms it?
The carpal tunnel is formed by the carpal bones and the overlying flexor retinaculum. It is through this tunnel that most, but not all, of the long flexor tendons originating in the forearm enter the hand. The flexor retinaculum is attached to four bony points - the pisiform, the hook of hamate, the scaphoid and the trapezium.
The carpal tunnel is narrow and no arteries or veins are transmitted through it because of the risk of compression. The median nerve does pass through however, and is at risk of compression.
What are the contents of the carpal tunnel?
9 tendons and 1 nerve:
- 4 tendons of flexor digitorum superficialis
- 4 tendons of flexor digitorum profundus
- 1 tendon of flexor pollicis longus
- median nerve
Why is the arrangement of the synovial sheaths of the flexor tendons important?
The synovial sheaths surround the flexor tendons and reduce friction between the tendons and the fibrous flexor sheaths of the digits. The tendon of flexor pollicis longus has its own synovial sheath which forms the radial bursa. Whilst flexor digitorum profundus and superficialis share one called the ulnar bursa that ends in the palm except for the little finger.
This arrangement is important in tendon sheath infections. Infection of the little finger sheath can spread to the whole of the ulnar bursa and even to the radial bursa through a communication that sometimes exists between them. Infections of other fingers however, are restricted to that finger.
What type of joint is the wrist?
The wrist is a condyloid synovial joint. The distal radius and a triangular disc of fibrocartilage covering the distal ulna form the proximal articulating surface. This disc is attached to the ulnar notch of the radius and to the base of the styloid process of the ulna. It separates the wrist joint from the inferior radio-ulnar joint. The distal articulating surface is formed by the scaphoid and lunate bones.
What is the nerve supply to the wrist joint?
Nerve supply comes from the anterior interosseous (median) and posterior interosseous (radial) nerves.
What is Dupuytren's contracture?
This is painless fibrotic thickening of the palmar fascia with skin puckering and tethering. Ring and little fingers are affected the most.
It is often bilateral and symmetrical. As thickening occurs there may be MCP joint flexion. If interphalangeal joints are affected then the deformity can be very disabling.
What conditions are associated with Dupuytren's?
The cause of Dupuytren's is multifactorial. Possible causes include:
- Genetics (AD)
- Peyronie's disease
How is Dupuytren's treated?
Surgery (e.g. fasciectomy) aims to remove affected palmar fascia and release the contracture. As a general guide, if the patient cannot rest their palm flat on a flat surface (Hueston's table top test) then refer for surgery.
Recurrence is common.
What is a ganglia?
Ganglia are cysts and appear as smooth multilocular swellings containing jelly like fluid in communication with joint capsules or tendon sheaths. They may disappear spontaneously and local pressure may disperse them.
When does a ganglia require treatment?
A ganglia should only be treated if it causes the patient pain or pressure (e.g. compression of the median or ulnar nerve at the wrist). Aspiration via a wide bore needle may work or they may be surgically disected out. This gives rise to less recurrence but problems include painful scars, neurovascular damage and recurrence.