Distal Ulnar Fractures

What is Distal Ulnar Fractures?

The most common arm injuries treated in emergency rooms are those involving the end parts of the ulna and radius bones. It’s essential for first responders, doctors, and support staff to know how to handle these injuries. Usually, the best treatment for an injury to the end of the ulna bone is to first perform surgery on the radius bone. Once the radius bone is stabilized, the majority of such ulna injuries can heal well with just basic care. However, healthcare workers need to consider factors like the patient’s age, how active they are, and their expectations in order to get the best results.

While most injuries to the end of the ulna bone don’t need surgical intervention, there are cases where it’s needed. A lack of proper understanding of this condition could lead to the bones healing abnormally, weakened ability to grip, and other serious issues. This summary aims to provide healthcare professionals in various fields with a better understanding of how to manage injuries to the end of the ulna bone.

What Causes Distal Ulnar Fractures?

People often fracture their wrist, specifically the ulna and radius bones, by falling on an outstretched hand. The wrist is usually bent back when this happens. In older people, the fracture is usually outside the joint due to low-energy incidents. Young people, however, tend to have fractures within the joint due to high-impact injuries. The harder the impact, the more likely both the ulna and radius will be fractured.

The ulna styloid, a part of the ulna, is the most commonly fractured part and is involved in 80% of joint fractures of the radius. The less common occurrence is a fracture at the upper end of the ulna, which can cause wrist instability. Only 5% of the radius fractures are associated with such intra-articular fractures of the ulna.

Sometimes, the ulna can fracture without any injury to the radius. This usually happens when a direct blow is received on the ulna – often when someone is using their arms to protect themselves. However, a much rarer mechanism involves extreme twisting of the arm. Doctors should be mindful of the possibility of domestic abuse whenever an upper-arm fracture occurs, particularly if the cause isn’t clear. Though recent studies have not been able to establish a direct correlation between this type of fracture and abuse in children.

It’s rare for only the growth plate area of the ulna to be injured, but when this happens, early growth plate closure is a risk. This is a matter of concern since up to 80% of ulna growth depends on this epiphyseal plate. Isolated fractures of the tip and the middle of the ulna are also rare. The fibrocartilage complex and the joint between the radius and ulna, parts providing support to the wrist, are commonly injured as well.

Risk Factors and Frequency for Distal Ulnar Fractures

Fractures of the distal radius, the bottom part of one of the bones in your forearm, are a common injury. They make up 1 in 6 fractures treated in urgent care and comprise 1.5% of all emergency department visits. Over 40% of these fractures also involve an injury to the distal ulna, a nearby bone in your forearm. These kinds of fractures tend to affect young men and older women the most.

Having weak bones due to osteoporosis significantly increases the risk of these fractures, especially in older individuals and women who have gone through menopause. Other risk factors include being overweight, having a history of falls, excessive drinking of alcohol, and suffering from dementia. These highlights the need for healthcare providers to be ready for a rise in these injuries as people are living longer.

• In children, fractures of the distal ulna make up 5% of growth plate (physeal) fractures.
• The most common type of this fracture in children is the Salter-Harris type II, where the fracture extends from the growth plate into the wider part of the bone (metaphysis).

Signs and Symptoms of Distal Ulnar Fractures

Examining someone for a broken wrist starts by looking at their health history. Details like age, which hand they use the most, how the injury happened, if they’ve had previous surgeries, if they have weak bones or drug or alcohol use. Additional factors like any decrease in movement, or other health conditions, are also taken into account. It’s especially crucial to know how the injury happened, such as how hard they were hit, what position their arm was in, and any sudden changes in movement, strength, or feeling afterwards.

The physical exam starts by checking both arms to compare strength, feeling and movement. The doctor then checks the injured arm for swelling, bruising, scrapes, open wounds and deformities. They can then determine if they need to act urgently or not. Finding a specific area of tenderness needs careful attention, focusing on areas like the ulnar styloid (a bony bump on the outer side of the wrist), and Lister’s tubercle (a small bump on the top of the radius bone in the forearm).

The doctor will also check for any nerve damage. They’ll use hand signals like the “OK” sign, “thumbs up” sign, “crossing the fingers” maneuver, and “wrist drop” to check for problems with various nerves in the forearm. To check for any blood vessel damage, they’ll look at the rate of capillary refill, do an Allen’s test (checking blood supply in the hand), and maybe even use a Doppler ultrasound.

There are specific tests for the distal ulna (the bone on the outer side of the forearm). This involves closely inspecting the ulnar side of the wrist for tenderness. The doctor might also perform the “fovea sign” test that can indicate various conditions, like disruptions to the fovea (a small pit), ligament injuries, or instability in the distal radioulnar joint (DRUJ) – the pivot point where the two bones of the forearm meet.

The stability of the DRUJ is checked before and after repairing a broken radius bone located at the wrist end. This helps decide if additional surgery on the distal ulna might be needed. Though there’s ongoing debate about what constitutes an “unstable” DRUJ, this evaluation is still a standard procedure.

An “unstable” DRUJ is defined as abnormal movement of the radius bone around the distal ulna in the forearm’s rest, turned inward, and outward positions. The ulnocarpal stress test is another test to help identify potential damage to the triangular fibrocartilage complex (TFCC) or other injuries.

• Fovea Test:
  • Place the forearm in a straight position.
  • Feel for the bump on the outer side of the wrist (ulnar styloid process).
  • Locate the flexor carpi ulnaris tendon (FCU).
  • The fovea is located between the outer wrist bump and FCU.
  • It’s just above the level of the pisiform (small bone in the wrist) and just below the head of the ulna bone.
  • If there are signs of pain when pressure is applied on the ulnar fovea, the test is positive.
• DRUJ Test:
  • Bend the patient’s elbow to 90 degrees and position the forearm neutrally.
  • Hold the distal parts of the radius and ulna bones.
  • Move the distal ulna up and down while keeping the distal radius fixed.
  • Repeat these steps with the forearm turned inwards and outwards.
  • If there’s increased looseness in the joint, or a lack of stopping point, the DRUJ is considered unstable.
• Ulnocarpal Stress Test:
  • Place the patient’s wrist in maximum ulnar deviation.
  • Rotate the wrist inwards and outwards while applying axial stress.
  • If there’s pain on the outer side of the wrist, the test is positive.

Testing for Distal Ulnar Fractures

Doctors use standard medical tests like a Complete Blood Count (CBC), a Basic Metabolic Panel (BMP), and a C-reactive protein (CRP) test to prepare for potential surgery or rule out an infection. However, these tests don’t help in diagnosing a fracture in the farthest part of the ulna bone in your arm.

X-rays are the best way to diagnose fractures in your forearm. Initially, your doctor will examine different views of your elbow, forearm, and wrist. They will also examine your elbow in particular to exclude any hidden injuries. It’s important to check the angle and height of the radius bone in your forearm on an x-ray to determine if surgery is needed. The stability of the joint where the two bones of your forearm connect can be checked using a side view x-ray, although a CT scan gives a clearer picture. A difference of more than 5 mm in the space between these two bones in the injured wrist compared to the uninjured wrist on an x-ray may point to a dislocation in this joint.

A CT scan can be used if your doctor is preparing for surgery, suspects hidden fractures, or wants to examine in detail any fractures that are within the joint or involve the breakup of the bone. For fractures at the farthest part of the ulna bone, a CT scan can be used to check if the connecting joint is unstable, if there are injuries to the soft tissue or internal framework of the bone, if there are injuries to the ulna head, or if the fractures are only within the joint.

MRI is the best non-invasive technique to check for injuries in the soft cartilage or the connecting joint of your forearm bones, although examining the area directly through a small camera (arthroscopy) is the most accurate way to check these injuries. An MRI can also show if the cartilage is torn in the middle or at the edges. Although some studies show that injecting a dye into the joint prior to an MRI (Magnetic Resonance Arthrography or MRA) may give a more accurate picture of the extent of cartilage tears, this technique is not commonly used. MRI can also be used to prepare for surgery, similar to CT scans.

Ultrasound can be used to quickly identify fractures in an emergency setting without exposing the patient to radiation. This makes it a good alternative for people who are sensitive to radiation, like kids and pregnant women. It has also shown promise in identifying injuries to the ligaments. A review of 16 studies involving over 1,200 patients showed that ultrasound is very accurate in diagnosing fractures in the forearm. However, one main drawback is that the accuracy of ultrasound depends more on the person doing the ultrasound compared to other techniques.

Treatment Options for Distal Ulnar Fractures

When it comes to fractures situated at the far end of the ulna bone in the arm, most are treated without surgery. First, any fracture of the nearby radius bone is stabilized. After that, the ulna fracture is evaluated. Surgery is typically only considered for a specific part of the ulna if the displacement is more than 2mm. When the joint between the radius and ulna (DRUJ) is stable, it is usually treated with a long cast for 2 to 4 weeks. If the joint is unstable, it might need surgery.

If the fracture appears to be healing correctly, the long cast can be changed to a short cast for the next 4 to 6 weeks. Earlier mobilization and movement are vital to a successful recovery. Some studies even showed that beginning movement early can lead to the same functional outcomes as surgery in the case of isolated ulna fractures.

Surgical treatment is considered if the ulna fractures are not repositionable and unstable. If the radius is also affected and needs surgery, the ulna fracture is examined during that same operation. If it’s unstable too, it is repaired during the surgery. Some types of fractures need open reduction and internal fixation. This is mainly if the ulna is displaced in a direction that indicates a ligament is detached.

Various surgical techniques are available, like Kirschner wires for quick and minimally invasive fixation, plate screw fixation, and salvage procedures if the fractures are very complicated. The Darrach procedure, Suave-Kapandiji procedure, and ulnar head arthroplasty are some of the salvage procedures.

For fractures of the ulnar styloid, it’s debatable whether surgical or non-surgical treatment is best. Factors like the degree of displacement and fracture pattern dictate the course of treatment for fractures of the ulna’s metaphysis. If the fractures are undertreated, it might affect the performance of the forearm.

For fractures of the ulnar neck or shaft, surgery is considered if the bone can’t be repositioned or if there’s significant displacement. The surgical method chosen doesn’t appear to have a major impact on outcomes, according to a 2012 study.

Fractures of the ulnar head typically require surgery, except for those rare cases where fractures are minimal and not displaced. Finally, tears of the triangular fibrocartilage complex, a structure in the wrist, normally heal without surgery. But in some cases, if the DRUJ remains unstable despite fixation of the radius and ulna, intervention could be considered.

What else can Distal Ulnar Fractures be?

When trying to diagnose a certain condition, doctors consider various possibilities because several health issues may present with similar symptoms. Some of these could be:

• Forearm fractures
• Fracture at the end of the radius (the larger bone of the forearm)
• Arthritis of the distal radioulnar joint (where the two forearm bones meet)
• Non-healed or wrongly healed bone where the ulna (smaller bone in the forearm) meets the wrist
• Injury to the distal radioulnar joint
• Displaced distal radioulnar joint
• Fracture or dislocation of the elbow
• Injury to the muscle that extends the wrist and moves the little finger away from the hand
• Inflammation of the tendon of the muscle that extends the wrist and moves the little finger away from the hand
• Galeazzi fracture (a specific type of forearm fracture)
• Fracture of a small bone in the wrist
• Isolated fracture of the ulna (the bone on the little finger side of the forearm)
• Arthritis of the joint formed by the pisiform and triquetral (two small bones in the wrist)
• Injury to the triangular fibrocartilage complex (a structure in the wrist that provides stability and cushioning)
• Fracture or non-healed bone of the triquetral (a small bone in the wrist)

And also consider these specific syndromes or conditions:

• Ulnocarpal abutment syndrome (a wrist condition usually caused by overuse)
• Arthritis in the ulnocarpal joint (where the ulna meets the bones of the wrist)
• Ulnar tunnel syndrome (when the ulnar nerve in your wrist is compressed)
• Ulnar variance (a situation in which the two bones of the forearm are not in their normal alignment)

Clearly understanding the symptoms and performing accurate tests are pivotal to figure out the actual health issue.

What to expect with Distal Ulnar Fractures

Fractures in the lower part of the ulna, a bone in the forearm, typically heal well when treated correctly. Many factors contribute to this, and the best healing outcomes occur when treatment is tailored to the patient’s specific needs. A study by Xiao and colleagues showed that simply immobilizing the fracture with a cast often leads to the best outcome in terms of regaining motion. Using a K-wire, a type of surgical pin, to stabilize the fracture in the lower part of the ulna was found to be the best method for restoring grip strength. However, patient satisfaction and long-term functionality didn’t differ with these treatments.

Fractures in the ulnar styloid, a part of the ulna near the wrist, usually have good outcomes without needing surgery. Successful healing of these fractures, even when the bone is displaced by more than 2mm, has been shown by a study by Kim and colleagues. Ayalon and others found no significant difference in the healing rates between fractures inside the joint compared to those outside the joint.

Fractures in the non-styloid area of the lower ulna often require surgery for satisfactory healing, especially when compared to fractures in the styloid area. In particular, comminuted intraarticular fractures, where the bone breaks into several pieces within a joint, and fractures in the head of the lower ulna have a poorer outlook and usually require surgery. These fractures are more likely to lead to chronic issues, including weaker grip strength, decreased range of motion, and persistent pain.

Possible Complications When Diagnosed with Distal Ulnar Fractures

Distal forearm fractures can lead to various complications, such as compartment syndrome, neurovascular injury, tendon rupture, arthritis, carpal tunnel syndrome, and malunion/nonunion. When not appropriately managed, a distal ulnar fracture might lead to decreased wrist movement, long-term pain on the ulnar side of the wrist, instability, tendon injury, and arthritis. It’s common for the embedded fixative hardware to be removed due to patient discomfort, primarily due to less soft tissue coverage at the distal ulna compared to the distal radius.

The ulnar nerve and artery, located near the flexor carpi ulnaris, can be injured during dissection and plate fixation. Another concern is injury to the distal radioulnar joint, which can cause damage to certain wrist and finger extensors. Such an injury can lead to ligament entrapment, limited wrist movement and reduced grip strength.

A malunion (improper healing) of a distal ulna fracture is uncommon if the fracture has been appropriately reduced and fixed. Malunion is also unlikely to occur in corresponding distal radius fractures if only the distal radius is treated. When patients show symptoms, these can be treated with bone grafts.

Incidence of nonunion (failure to heal) of ulnar styloid fractures falls between 20% to 70%. Despite these numbers, most cases don’t show symptoms and are managed conservatively. Symptomatic patients often present with ulnar-sided wrist pain, especially during rotation. When symptoms persist, surgery may be considered, particularly if the nonunion threatens wrist stability. Nonunion can rarely lead to other complications, and treatment options include excision, arthroscopic intervention, bone graft, or osteotomy.

Specific surgical procedures can also lead to complications:

• Darrach Procedure may cause pain and impingement of the radioulnar.
• Tension Banding might result in nerve and soft tissue irritation because of pin placement or migration.
• Plate Fixation often causes symptomatic hardware prominence, irritation of the dorsal branch of the ulnar nerve, longer operative times, and tendinopathy or tendon rupture.
• Scheker DRUJ Prosthesis often causes a specific type of tendinitis but can be managed by placing a certain type of tissue between the prosthesis and tendon.

Preventing Distal Ulnar Fractures

It’s important for parents, caregivers, and health workers to understand that injuries to the upper arms or hands could be a clue to unnoticed, intentional harm, particularly in vulnerable groups. To lay this suspicion to rest, a thorough medical examination and background assessment should be carried out. Besides, patients and their families should be informed about the potential complications that can arise from a fracture in the distal ulna, the bone in the forearm, which may or may not require surgery. Serious complications can consist of a condition where excessive pressure builds up in a muscle compartment, damage to nerves or blood vessels, hidden fractures, and discomfort from surgical implants.

If a patient experiences sudden weakness, unusual sensations (like tingling or numbness), their extremities becoming cold, or noticeable changes in skin color, they should instantly seek medical attention. Such signs could indicate serious complications that require immediate intervention.