Undifferentiated spondyloarthritis as a source of back and joint pain

Undifferentiated spondyloarthritis as a source of back and joint pain
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Spondyloarthritis affects the spine and peripheral joints. It is the name for multiple diseases with similar characteristics. It causes pain in the spine and joints, problems affecting the eyes, skin, mucous membranes and intestines.


Spondyloarthritis = rheumatic inflammatory damage to the spine and peripheral joints.

The name signifies a group of several diseases.

SpA, the abbreviation used for spondyloarthritis, is the common name for several diseases affecting the spine and peripheral joints. They not only cause pain in the sufferer's back, shin, hip, lower back and joint pain, but the problems also affect the eyes, skin, mucous membranes, digestive tract, and the intestine.

The inflammatory process damages the joint, more precisely the connective tissue between tendon or ligament and bone,as enthesitis.

The group of spondyloarthropathies includes:

This form of inflammation mainly affects the axial skeleton, i.e. the spine, and the connection between the sacrum and the pelvis - the sacroiliac joint, as sacroiliitis and spondylitis.

Peripheral joints are also affected, especially those of the lower limbs, such as the hip, knee, ankle, and other parts, such as the elbow, wrist, and small joints of the fingers and toes.

They are also referred to as seronegative spondyloarthritis.

Forms of spondyloarthritis have common features such as:

  • rheumatic inflammatory diseases
  • absence of rheumatoid factor - RF = seronegativity
  • absence of rheumatic nodules
  • typical oligoarthritis - inflammation of up to 4 joints simultaneously - arthritis
  • dactylitis or sausage digit is inflammation of an entire digit
  • sacroilitis and spondyloarthritis - inflammation within the sacroiliac joint and inflammation of sacroiliac joints and spine - facet joints
  • familial occurrence
  • association with the HLA-B27 marker
  • extra-articular manifestations - affecting the eyes, skin, mucous membranes, cardiovascular or digestive system

They occur at all ages and in both sexes.

But, what is undifferentiated spondyloarthritis?
Would you like to find out more? 
Read on.

Undifferentiated spondyloarthritis is...

The term undifferentiated spondyloarthritis means that it is a seronegative spondyloarthritis that does not yet have any signs of any differentiated disease.

An example of a classified diagnosis is axial spondyloarthritis,
psoriatic arthritis,
reactive or enteropathic arthritis.

There are common manifestations, but at the time of diagnosis it is not yet precisely developed.

Later on, the manifestations of the disease can be precisely differentiated, when a specific type of spondyloarthritis develops.

However, some cases remain undifferentiated throughout the sufferer's lifetime.

Undifferentiated  = incomplete form of the disease. 
The usual abbreviations are USpA or ndSpA. 

At the time of diagnosis, the doctor is not yet able to classify the disease as an accurate diagnosis, so they will determine it as an unclassified form of spondyloarthritis. This is because the symptoms present are not conspicuous enough to make a specific diagnosis.

The persistence of inaccurate problems can lead to misdiagnosis. People who complain of vague health problems are often labeled as anxious or depressed.

This may be a precursor to another rheumatic disease.

Undifferentiated spondyloarthritis = early stage or incomplete form of spondyloarthritis.


The cause of undifferentiated spondyloarthritis, like other forms of spondylarthritis, is unknown. It might be an interaction of several factors, the most significant being the presence of a human leukocyte antigen (HLA).

A multifactorial effect is considered to play a role at the onset of the disease:

  • genetic predisposition and familial occurrence
  • positivity of the HLA-B27 marker - up tp 75 % of cases
  • external factors such as
    • the trigger can be overcome by a disease of bacterial or viral origin
    • effectivity of drugs, chemicals
    • and others

Relatives often have other diseases associated with the HLA marker
such as non-specific intestinal inflammation or celiac disease.

The basis is a pathologically altered immune response.
It is therefore an autoimmune process
in which immunity attacks the body's own cells and tissues.
These are various structures, such as cartilage and tendon tissue,
but also skin, intestinal mucosa or eyes. 


The disease is manifested by the presence of various symptoms. However, they are not sufficiently expressed to make an accurate diagnosis.

An example of problems of an unclassified form can include a combination of several health problems:
The sufferer has pain in the heel, swollen knees as well as inflammation and irritation of the eye.
However, there is no prior back pain or symptoms of intestinal inflammation.

Other manifestations may be associated at a later time. These then lead to the determination of a specific diagnosis.

In undifferentiated spondyloarthritis, symptoms and combinations thereof may occur such as:

  • pain in the back, sacrum, lower back, sacroiliac joint- axial disability
  • hip pain
  • joint pain - the peripheral joints of the lower limbs are most often affected
  • joint swelling
  • pain in the heels, feet, soles
  • stiffness of the joints and spine - morning stiffness and after inactivity are typical
  • limited range of motion - dysfunction
  • problems are aggravated by inactivity, long-term monotonous position, sitting, standing, lying down, or excessive physical activity
  • the pain is relieved by movement, mild stretching and warming up
  • inflammation of an entire digit - dactylitis, also called sausage digit
  • extra-articular manifestations
    • fatigue and general weakness
    • stomach ache
    • diarrhoea
    • loss of appetite and indigestion
    • irritation and inflammation of the eye, redness of the conjunctiva, itchy eye
    • skin rash and frequent mouth ulcers on the lining of the mouth
    • rise in body temperature

Inflammation most often occurs as monoarthritis or oligoarthritis and usually affects the joints of the lower limbs.

Monoarthritis - 1 joint. 
Oligoarthritis - 2 to 4 joints. 
Polyarthritis - 5 or more joints. 


Diagnosis is difficult, mainly due to non-specific issues. A diagnostic mistake can often occur, and sufferers might be described as anxious and depressed.

However, it is important to ascertain the situation based on the medical history, a physical examination, and examination of subjective and objective human symptoms.

Subjective symptoms are those that one feels.
Objective symptoms are those that can be observed from the outside.

It is important to take blood samples for laboratory tests, i.e. antibodies, the presence of the HLA-B27 gene, RF (rheumatoid factor) negativity, CRP, FW, and blood count.

Medical imaging methods like X-ray, CT, MRI, ultrasound are also used.

Colonoscopy and other endoscopic examinations to detect gastrointestinal involvement may be added. In cases of eye inflammation, an eye examination will be performed.


The undifferentiated form of spondyloarthritis is characterised by the fact that it does not contain sufficiently expressed or conspicuous symptoms that would classify it as bein one of the specific forms of spondyloarthritis.

Ankylosing spondyloarthritis is reported to develop in up to 60 percent of undifferentiated cases during the years of follow-up.

This is one of the reasons why some authors state that USpA is not a separate subunit, but rather an early stage of the disease.

However, in some people affected by this form, symptoms do not develop into any differentiated subtype and remain unclassified throughout their lives.

The disease develops at a young age and over decades. It affects both sexes.

Typically, rheumatic diseases present with a relapsing-remitting course, i.e. periods of symptom exacerbation and less severe symptoms.

  • remission = reduction of signs and symptoms, period of no evidence of disease
  • relaps = a recurrence of a medical condition

These two intervals alternate.

The onset can be slow, gradual, insidious, or acute.

It is a chronic, i.e. long-term progressive disease.

There are one or more observable manifestations in people:

  • inflammatory back pain - it is worsened by inactivity and alleviated by warm-up
  • unilateral or alternating back pain
  • tendonitis - heel and foot pain
  • pain in one or more joints - especially in large joints
  • swelling of the joint or finger
  • fatigue
  • eye inflammation and iritis are frequent - inflammation of the iris

Later on, there are other problems that lead to a specific disease.

The prognosis depends on several characteristics. Thus, the disease usually develops into a precise subtype based on which another course of action can be predicted.

Early diagnosis and timely treatment are important, which may slow the overall progression of the disease.

How it is treated: Undifferentiated spondyloarthritis

Treatment of undifferentiated spondylarthritis, medications and rehabilitation

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