Pseudarthrosis – False joint resulting from impaired bone healing in cases of pseudarthrosis

When it comes to this condition, you shouldn’t necessarily be guided solely by the name. That’s because it has nothing to do with normal osteoarthritis, which is usually caused by joint wear and tear.

The term “pseudarthrosis” is composed of “pseud” and “arthros.” “Pseud” means false, and “arthros” means joint. Pseudarthrosis is therefore a false joint that forms when the fracture sites do not heal properly after a bone fracture.

Although the bone ends grow together and form a connection, this connection does not become strong and stable as it should. Consequently, an articulated joint forms between the fracture ends at the site of the former fracture—a joint that did not exist previously. This false joint can lead to significant problems such as pain and restricted movement. “Pseudo-joint” and “false joint” are other terms used to describe pseudoarthrosis.

How do delayed fracture healing and pseudoarthrosis differ?

Normal, unimpeded fracture healing takes about 4 to 6 weeks, but in the case of complex fractures, it can take considerably longer—up to 12 weeks. 

If a fracture has not healed after 12 weeks, it is referred to as delayed fracture healing; after 6 months, it is considered pseudoarthrosis.

Long bones, also known as shaft bones, are particularly prone to pseudarthrosis. These include the femur, scaphoid, ulna and radius, and the humerus.

Pseudoarthrosis can have various causes. A basic distinction is made between mechanical and pathological causes of pseudoarthrosis. Mechanical causes refer to situations where movement and pressure have disrupted the bone’s healing process. Pathological causes involve disease states outside the bone, most commonly metabolic disorders or pathogens.

What are “mechanical” causes?

Mechanical causes generally include anything related to movement, most commonly premature weight-bearing and, consequently, insufficient immobilization. This is particularly important in the case of fractures treated conservatively. Conservative treatment means that the bone ends are not fixed together surgically using metal (wires, screws, plates), but rather the goal is to allow the bone to heal naturally. Surgical treatment is also referred to as osteosynthesis; “osteo” stands for bone and “synthesis” for union.

A prerequisite for conservative fracture treatment is that the bone ends are close together and aligned correctly. Immobilization is usually achieved with a cast (e.g., on the wrist) or by avoiding physical strain (e.g., in the case of rib fractures). 

A bone fracture normally heals within 6 weeks. If the bone tissue has not yet healed, moving or putting weight on the area too soon can ultimately do more harm than good and, in the worst case, lead to pseudoarthrosis.

Other mechanical causes may include:

• the displacement of soft tissues into the fracture site, which can occur with bleeding or large hematomas. The latter are usually due to 
• insufficient compression of the wound 
• the displacement of the fracture ends relative to one another when pressure or external impacts are applied. This can also lead to corresponding complications in the event of a fall

What are “morbid” causes?

Pathological causes must also be taken into account, but they are significantly less common. This category includes:

• disorders of calcium metabolism
• Infections
• Smoking
• severe obesity or underweight
• Narrowing of the arteries resulting in circulatory disorders
• Diabetes mellitus

Congenital metabolic bone disorders are also among the pathological causes, though they are rarely the underlying cause.

Pseudarthrosis can be classified into different categories based on bone structure and blood supply:

• Based on bone structure, it is classified as
  • hypertrophic pseudarthrosis, in which there is an increase in bone mass. However, this bone has reduced stability and is therefore unable to stabilize the bone ends.
  • atrophic pseudarthrosis, in which there is a reduction in bone and cartilage tissue. Here, the problem of insufficient stability is obvious.
• based on the blood supply to the bone tissue, into
  • vital pseudarthrosis, in which there is adequate blood supply, and 
  • avital pseudarthrosis, characterized by tissue with inadequate blood supply. 

Often, there is a combination of hypertrophic and vital on one side and atrophic and avital on the other. Atrophic avital pseudarthrosis has the poorest prognosis; but hypertrophic vital pseudarthrosis also involves a healing process that is often protracted and complex and frequently requires surgical revision to ensure proper healing in the correct alignment (i.e., without misalignment). 

There are various signs that may indicate pseudarthrosis. For example, a bone fracture that heals very slowly can be an initial sign. Persistent or even worsening pain—lasting longer than 4 to 6 months—is suggestive of pseudarthrosis. Typical symptoms may include:

• Pain in the area of the affected bones or joints
• Swelling
• Redness
• Limited range of motion
• Hypermobility—the opposite of limited mobility
• Joint instability

If you notice these symptoms in yourself, you should definitely undergo a medical examination to have the symptoms evaluated. Imaging techniques, primarily an X-ray, can reveal the pseudarthrosis and enable a more precise diagnosis. The X-ray shows a persistent bone gap at the site of the previous fracture that did not heal properly. Pseudarthrosis can be assessed even more accurately using computed tomography (CT) or magnetic resonance imaging (MRI). 

Treatment depends on the type of pseudarthrosis present. Treatment methods must be tailored to the specific cause. In the case of vital pseudarthrosis, a somewhat less invasive treatment approach can be taken, as the chances of healing are very good. Often, consistent continuation of immobilization is sufficient. 

The situation is different with avital pseudarthrosis, which usually requires surgical intervention. Good treatment outcomes can often be achieved using so-called osteosynthetic techniques (bone fixation with metal plates or screws).

In most cases, the bone ends must be “recontoured.” This means that dead, avital, and infected bone tissue is removed. In some cases, however, this results in a defect in the bone structure, making it necessary to fill the defect with a bone graft. This can be done using a cell culture specifically prepared from the patient’s own cells, or by removing bone tissue from another site. A suitable harvest site is the iliac crest.

A ring fixator is one option used to stabilize the bone. A ring fixator is a type of external support system that can be easily removed.

Also important: There is currently a great deal of discussion about a blood test designed to predict susceptibility to pseudarthrosis. If this proves successful, appropriate measures can be taken immediately upon the initial fracture. In addition, tissue samples from the section of bone affected by pseudarthrosis can be examined in a laboratory. This provides a better understanding of the risk of pseudarthrosis and the chances of a bone fracture healing.

In summary, the following treatment options are available for pseudarthrosis:

• bone-fixation methods (e.g., ring fixator)
• Grafting bone material into the fracture gap
• Removal of necrotic and infected tissue
• Administration of certain dietary supplements
• Possibly available soon: a blood test to determine susceptibility to pseudarthrosis.

In cases of pseudoarthrosis, several specialists may be consulted. For example, bone surgeons as well as orthopedic specialists may be involved. The attending physician will refer the patient to the appropriate expert.

What is pseudoarthrosis?

Pseudoarthrosis is a false joint that develops when bones do not heal properly after a fracture or break. The fracture gap remains open, and the affected bones do not fully fuse together. The term “pseudarthrosis” comes from Greek and describes a “false joint.”

What causes pseudarthrosis?

Common causes of pseudarthrosis include inadequate immobilization of the affected bone, infection, or poor blood circulation. Diabetes, significant mechanical stress, or misalignment can also impair fracture healing. There is an increased risk of incomplete healing, particularly following fractures of the radius, humerus, or scaphoid.

How is pseudarthrosis diagnosed?

Pseudarthrosis is usually diagnosed through a clinical examination and imaging tests. If X-ray findings are inconclusive, the orthopedic surgeon often confirms the diagnosis with additional tests. A typical sign is delayed fracture healing beyond a period of 4 to 6 months.

What treatment options are available for pseudarthrosis?

Treatment for pseudarthrosis depends on the type and extent of instability. In addition to conservative treatment and therapy, surgical procedures for stabilization may be considered. Extracorporeal focused shock wave therapy has been shown to have a positive effect on bone formation in some patients and is sometimes considered an alternative to surgical treatment.

When is surgery necessary for pseudarthrosis?

Surgery for pseudarthrosis becomes necessary if the bone fails to heal despite therapy or if atrophic pseudarthrosis or avital pseudarthrosis is present. In such cases, a surgical procedure is usually performed to stabilize the joint using additional bone graft material from the iliac crest. The goal is to permanently restore the bone’s stability.