Orthopaedics - Hand, wrist and elbow Flashcards
What is the difference between the anatomical and surgical neck of humerus?
The anatomical neck is located on the proximal humerus. It separates the head from the greater and lesser tubercles.
The surgical neck lies below the anatomical neck between the upper end of the humerus and the shaft. Importantly, the axillary nerve and circumflex vessels wind around the surgical neck of the humerus. These are all at risk in shoulder dislocations and humeral neck fractures.
What is the function of the greater and lesser tubercles?
These provide an insertion site for the rotator cuff muscles. They are separated by an intertubercular sulcus or bicipital groove, in which the long head of the biceps runs.
What is the spiral groove?
This is a faint groove located on the posterior aspect of the shaft of the humerus. The medial and lateral heads of triceps originate from either side of this groove and the radial nerve passes between these 2 heads.
What nerve passes behind the medial epicondyle to enter the forearm?
The ulnar nerve winds around the medial epicondyle and passes into the cubital tunnel. It emerges to run between the two heads of flexor carpi ulnaris which it supplies.
What part of the distal humerus does the ulnar and radius articulate with?
At the elbow joint, the trochlear of the humerus articulates with the trochlear notch of the ulnar. The rounded capitulum of the distal humerus articulates with the radial head. The medial border of the trochlear projects a little more inferiorly than the lateral border. This accounts for the carrying angle - i.e. the slight lateral angle made between the arm and forearm when the elbow is extended.
What is the olecranon fossa?
This is a depression on the posterior aspect of the distal humerus, which accommodates the olecranon of the ulnar. It permits flexion and extension movements.
Where does the biceps tendon insert?
The biceps tendon inserts onto the radial tuberosity. Specifically it inserts onto the rough posterior part. The anterior part of the tuberosity is smooth where it is covered by a bursa.
Where are the ulnar and radial heads?
The radial head is located proximally and articulates with the capitulum of the distal humerus. The ulnar head is distal. The ulnar head does not play a part in forming the wrist joint. The trochlear notch on the proximal ulnar articulates with the trochlear at the elbow joint.
How do the radius and ulnar move during pronation and supination movements?
The ulna remains relatively fixed and the radius does all the moving! The radius rotates along the radial notch in the proximal ulnar and the radial shaft pivots around the ulnar. The two are connected by an interosseous membrane. The distal radius rotates around the head of the ulnar.
What type of joint is the elbow joint?
The elbow is a synovial hinge joint (unlike the shoulder which is a ball and socket joint). At the elbow, the humeral capitulum articulates with the head of the radius, and the trochlear of the humerus articulates with the trochlear notch of the ulna.
There are 2 fossae located above the trochlear and capitulum to accomodate the capitulum of the ulna and the radial head respectively, during full flexion.
The elbow joint communicates with the superior radio-ulnar joint.
Where is the elbow joint capsule?
The elbow joint capsule is lax in front and behind to permit a range of movements. It is also more extensive posteriorly to accomodate fat pads. It covers the bony articular surfaces and both coronoid and radial fossae on the humerus. But the medial and lateral epicondyles are both extra-articular an extra-capsular.
Where are the collateral ligaments of the elbow located?
There is a medial and a lateral collateral ligament on the elbow.
The medial collateral ligament is triangular and consists of anterior, posterior and middle bands. It extends from the medial epicondyle of the humerus and the olecranon to the coronoid process of the ulna. The ulnar nerve lies adjacent to the medial collateral ligament as it passes forwards below the medial epicondyle.
The lateral collateral ligament extends from the lateral epicondyle of the humerus to the annular ligament. The annular ligament is attached medially to the radial notch of the ulna and clasps, but does not attach to the radial head and neck. Because of this, the radial head is free to rotate within the ligament.
What are the movements of the elbow?
Flexion and extension occur mainly at the elbow joint.
Pronation and suppination occur at the superior radio-ulnar joint.
Flexion - is achieved by the anterior arm muscles, biceps, brachialis and brachioradialis.
Extension - triceps mainly, and anconeus
Pronation - pronator teres and pronator quadratus
Supination - biceps is the most powerful supinator. This is because of the insertion of the biceps tendon into the posterior aspect of the radial tuberosity. Supinator, extensor pollicis longus and brevis are weaker supinators.
What are the boundaries of the cubital fossa?
The fossa is defined by a horizontal line joining the two epicondyles, the medial border of brachioradialis and the lateral border of pronator teres.
The floor of the fossa is formed by brachialis muscle and the roof by superficial fascia. The median cubital vein runs in the roof of the fascia and drains into the basilic and cephalic veins.
What is the biceps tendon and important landmark for in the cubital fossa?
The biceps tendon can be easily palpated in the fossa. Medial to the biceps tendon is the brachial artery and the median nerve.
NB - the radial and ulnar nerves lie outside the fossa. The radial nerve passes anterior to the lateral epicondyle between brachialis and brachioradialis muscles. The ulnar nerve winds behind the medial epicondyle.
What are the common presenting complaints of elbow pathology?
Most patients will present with either:
- pain
- locking, caused by loose bodies
- pins and needles, hand weakness
What is tennis and golfer’s elbow?
Tennis elbow is lateral epicondylitis, golfers elbow is medial epicondylitis.
Patients are often middle aged and may have a history of pain commencing after minor trauma. There may be a recent history of excessive activity involving the elbow (but this is rarely tennis!).
In tennis elbow the pain is located on the outer aspect of the elbow, whereas in golfers elbow the pain is located medially.
The exact cause of pain is unknown, but it is likely to be caused by vascular repair due to tendon microtrauma.
What is Mill’s test?
This is pain felt over the lateral or medial elbow on resisted wrist extension or flexion respectively. It suggests tennis or golfers elbow.
NB - the reason the pain is felt either on extension or flexion is because the lateral or medial epicondyles are the origin of the long forearm extensors and flexors respectively.
What is the management of tennis or golfer’s elbow?
Management is:
1) conservative - NSAIDs, activity modification (avoid precipitating movements), physio, steroid + local anaesthetic injection
2) surgical - persistant pain which fails to respond to conservative measures. The collateral ligament on the side of pain is removed from the humeral epicondyle which decompresses the elbow
What is olecranon bursitis? What other differentials are there?
This is otherwise known as “student’s elbow” and is a traumatic bursitis following pressure on the elbows - e.g. while reading a book.
Symptoms are pain and swelling behind the olecranon. Other differentials are septic arthritis (check for signs of sepsis) and gout bursitis (check for tophi).
The bursa should be aspirated and a sample sent for MC&S and crystals (gout crystals are negatively birefringent).
Treatment is usually with steroid injections directly into the joint with local anaesthetic. If the cause is infective then the joint needs surgical drainage to remove pus followed by IV antibiotics.
What is ulnar neuritis?
Ulnar neuritis is also called “cubital tunnel syndrome”. It occurs due to impingement of the ulna nerve as it passes behind the median epicondyle.
Causes include:
- osteoarthritic and rheumatoid narrowing of the ulnar groove
- friction of the nerve due to cubitus valgus (congenital abnormality) and nerve fibrosis
- dislocation
- supracondylar fracture (most common fracture in children)
How does ulnar neuritis present?
Sensory symptoms usually occur first - e.g. decreased sensation in the ulna nerve distribution, ulnar 1.5 fingers . Patients may experience clumsiness of the hand and weakness of the small muscles supplied by the ulnar nerve (of the 20 bones in the hand the ulnar nerve supplies 15).
How is ulnar neuritis diagnosed?
Diagnosis is usually clinical, but nerve conduction studies can be performed to isolate the site of the lesion. Ulnar neuropathy can occur at multiple sites from the elbow downwards with the cubital tunnel and Guyon’s canal be most common.
How is ulnar neuritis treated?
Management is conservative followed by surgery. Surgical intervention is usually offered if patients are not responding to conservative therapy, being kept awake by night time pain or decreased function. It involves decompression +/- transposition of the nerve to the front of the elbow (often only performed if the nerve subluxes over the medial epicondyle during decompression).
What is the ulnar paradox?
The ulnar nerve can be damaged at various points from the elbow downwards. When the ulnar nerve is damaged at the wrist in Guyon’s canal the hand becomes clawed. The interossei and lumbricals usually produce flexion at the MCP joints and extension at the IP joints. When the function of the interossei and lumbricals is lost, the opposite happens and the MCP joints become extended and IP joints flexed. This is less noticeable in the index and middle fingers because they retain their lumbrical muscles which are supplied by the median nerve.
If the ulnar nerve is injured at the elbow or above, the ring and little fingers get straighter as the ulnar supply to flexor digitorum profundus gets lost which means they are held in a less flexed position. But, this results in greater functional disability. This is the paradox, we would expect the clawing to become worse the higher the injury but it appears to get better.
What are the features of osteoarthritis of the elbow joint?
OA of the elbow joint presents as pain and stiffness in all elbow movements, e.g. flexion, extension and forearm rotation. Loose bodies may cause further restriction of movement - e.g. loss of full extension.
Primary OA of the elbow is rare, and it normally occurs secondary to fractures or osteochondritis dissecans.
How is elbow OA treated?
Treatment is mostly conservative - activity modification, phsyiotherapy, NSAIDs, analgesics.
Surgery is rarely needed, but procedures include removal of loose bodies, debridement , joint replacement or radial head excision.
What is cubitus valgus?
There is a normal degree of valgus called the carrying angle of between 10-15 degrees. Fractures at the lower end of the humerus or interference of the epiphyseal growth plate (i.e. causing arrest) may cause this angle to be greater. As a result, patients are more prone to OA and ulnar neuritis.
