Common Conditions of the Thumb

Many different conditions can affect the normal function of the thumb (Figure 1). It is important to recognize the most common conditions so appropriate treatment can be given.

Stenosing Tenosynovitis (Trigger thumb) (Figure 2)

One of the more common abnormalities of the hand associated with painful triggering or locking of the thumb is stenosing tenosynovitis. When the patient tries to straighten the thumb, the nodule jams beneath the pulley proximally.

Extensor Pollicis Longus Tendon Rupture (Figure 3)

The EPL tendon is responsible for extension of the thumb’s distal interphalangeal joint. When a rupture occurs, the patient will experience loss of thumb extension and this typically occurs due to fracture of the distal radius. Rupture of this tendon prevents the extension of the distal phalanx.

Entrapment of the Posterior Interosseous Branch of the Radial Nerve (Figure 4)

The posterior interosseous nerve is a continuation from the radial nerve and runs through the forearm. The nerve passes through the supinator muscle of the forearm, found on the outside of the elbow. The nerve becomes entrapped at the proximal edge of the supinator. Injury of the nerve may also be associated with fractures or dislocations of the radial head or the elbow joint. The patient will be able to perform wrist extension but not finger extension.

Unable to do the OK Sign (Figure 5)

The anterior interosseous nerve branches from the median nerve just below the elbow and supplies the deep muscles on the front of the forearm. Typically, there will be weakness of the long flexor muscles of the thumb (Flexor Pollicis Longus) and the deep flexor muscles of the index and middle fingers.

Injury to the Ulnar Nerve (Froment’s Sign) (Figure 6)

Cubital tunnel syndrome occurs due to compression of the ulnar nerve at the elbow. As a result of cubital tunnel syndrome, the patient is unable to cross or abduct the fingers. When pinching a piece of paper between the thumb and index finger, the thumb IP joint will flex if the adductor pollicis muscle is weak.

Rheumatoid Arthritis of the Thumb (Figure 7)

Rheumatoid arthritis is inflammation or irritation causing pain, swelling, weakness, and overtime, loss of the normal shape and alignment of the joint. This deformity can lead to the loss of the ability to grip, grasp, and pinch.

Elbow Bursitis

Elbow bursitis is a filled sac at the tip of the elbow due to trauma, infection or inflammation. Because of the swelling and the bump that develops at the tip of the elbow, this is sometimes referred to as a popeye elbow.

The normal olecranon bursa provides protection and decreases friction to the elbow joint; it contains a small amount of fluid.

Olecranon bursitis causes pain, swelling, tenderness and a lump in the area at the tip of the elbow. It may be difficult to put the elbow down on a surface due to the tenderness.

Bursitis of the elbow can occur due to trauma, infection, inflammation and medical conditions (like gout or rheumatoid arthritis).

Treatment of elbow bursitis includes anti-inflammatory medications, antibiotics (if the infection is suspected), ice therapy, aspiration and surgery. A protective covering should be placed around the elbow while avoiding activities that aggravate the condition.

 

Ganglion Cyst

Ganglion of the wrist is the number one soft tissue hand mass. If a mass is present in the wrist, there is a 70% probability that it is a ganglion.

 

The bump or the cyst is filled with gelatinous material that can change in size and is close to a tendon sheath or the wrist joint. The causes of cysts are unknown. It may be caused by trauma or degeneration and weakness of the capsule.

Ganglion cysts of the wrist can be either dorsal or volar. A ganglion cyst that grows on the top of the wrist is called a dorsal ganglion. Dorsal ganglion is common (70%) and arises from the scapholunate ligament. A ganglion cyst that grows on the bottom of the wrist is called a volar ganglion. These are less common (20%), but are most common between the Flexor Carpi Radialis (FCR) and Abductor Pollicis Longus (APL) muscles. Volar cysts arise from the radiocarpal joint or the STT joint.

For a dorsal cyst, the bump or the mass is well defined, localized, smooth and not attached to the underlying skin. The mass will be translucent. The mass is obvious with flexion of the wrist, so an MRI is not needed. A volar cyst may be diagnosed with an MRI; however, ultrasound imaging is better for showing the relationship between the artery and the ganglion.

Femoral Neck Fractures

Stress fractures of the femoral neck are most commonly seen in athletes, such as runners. Females are more common than males to experience stress fractures of the femoral neck. Beware of female runners with pain in the groin and normal x-rays.

Clinical findings

The clinical findings for stress fractures of the femoral neck include groin pain, pain with weight bearing activity and negative x-ray in about 2/3 of the patients. An MRI is the best study when diagnosing stress fractures of the femoral neck. Exclude other causes of hip pain such as transient osteoporosis and avascular necrosis.

Types of Stress Fractures

Compression fractures

Compression fractures are a callus at the inferior aspect of the femoral neck. If the fracture involves less than 50% of the femoral neck, it can be treated with non-weight-bearing and crutches, as well as restricted activity. If the fracture involves more than 50% of the femoral neck, it should be treated with screw fixation.

Tension Fracture

A tension fracture is a fracture at the superior aspect of the femoral neck. The adult bone is weak in tension and with tension the fracture will propagate. Treatment should be done with screw fixation.

Displaced Fracture

A displaced fracture will have a bad prognosis especially with younger patients. There is risk of avascular necrosis and nonunion with displaced fractures. This is considered to be an emergency in younger patients. Perform a reduction and screw fixation for treatment of these fractures. It is necessary to obtain an MRI to rule out a stress fracture in elderly patients with groin pain and a normal x-ray. Use a prosthesis in the elderly.