What is the Baastrup phenomenon?
The Baastrup phenomenon describes a specific change in the spine where the spinous processes, the small, easily felt bony bumps on the back of the spine, of neighbouring vertebrae touch or even rub against each other. This is also known as "kissing spine" because the bones are, in a way, "kissing" each other. The lower part of the lumbar spine is most commonly affected.
How does the Baastrup phenomenon develop?
Normally, there are small gaps between the spinous processes so that they do not touch during spinal movement. However, certain types of strain, age-related changes, or an increased hollow-back posture can cause these bony projections to move closer together. Over time, they can come so close that they knock against each other during movement.
This repeated rubbing can lead to small changes in the bones. Thickening can develop, and sometimes small cysts or changes in the surrounding soft tissues appear. The Baastrup phenomenon occurs most often in older people, but it can also affect athletes who place a great deal of strain on their spine.
What symptoms can occur?
The Baastrup phenomenon does not always cause symptoms directly. Many people notice nothing at all, and the change is discovered by chance during an X-ray or MRI scan. However, there are also cases where the rubbing of the spinous processes causes pain in the lower back. This pain often gets worse when bending backwards (extension) and eases when the spine is bent forwards.
Some people report a dull, localised pain in the area of the affected spinal segments. In rare cases, irritated bursae or small areas of inflammation around the spinous processes can cause additional discomfort.
Is the Baastrup phenomenon dangerous?
The Baastrup phenomenon itself is not considered a dangerous condition. Many people live with it for years without ever having any problems. The changes to the spinous processes do not usually lead to lasting damage to the nerves or spinal cord. That said, recurring back pain or restricted movement in daily life can feel burdensome.
The biggest concern for many people is that a serious underlying cause is behind their back pain. However, the Baastrup phenomenon is a benign change that is usually age-related. Only in rare cases does it develop into more significant inflammation or a pronounced bursa irritation that requires targeted treatment.
How is the Baastrup phenomenon diagnosed?
The diagnosis is usually made using imaging methods such as X-rays or an MRI scan. The images often show that the spinous processes of two neighbouring vertebrae are touching or have become thickened. Sometimes small changes in the surrounding soft tissues, such as bursae, can also be seen.
It is important that the doctor carefully checks whether the symptoms are truly coming from the Baastrup phenomenon or whether other causes of back pain should be considered. It is not uncommon for several changes to be present at the same time, such as a slipped disc or wear and tear of the small vertebral joints.
What treatment options are available?
Treatment depends mainly on how severe the symptoms are. If there is no pain or only mild discomfort, no special therapy is usually needed. Many people benefit from targeted physiotherapy exercises that strengthen the back muscles and improve spinal mobility. Learning back-friendly movement habits can also help reduce the strain on the spinous processes.
For more pronounced pain, pain-relieving and anti-inflammatory medications are sometimes used. In certain cases, a cortisone injection at the irritated site can provide relief. Only very rarely, for example, when pain remains persistently severe and other measures have not helped, is surgery considered. In such cases, part of the spinous process can be removed to prevent the bones from knocking together.
What to keep in mind in daily life?
People affected by the Baastrup phenomenon generally do not need to worry about major restrictions. It is worth paying attention to good posture and getting enough movement. Exercises that strengthen the core muscles and keep the spine mobile can in particular help reduce the risk of pain. Excessive hollow-back posture or standing for long periods in an unfavourable position should be avoided where possible.
Regular check-ups with a doctor are sensible if back pain recurs or symptoms change. This makes it possible to recognise early on whether further measures are needed or whether other causes are responsible for the symptoms.
The Baastrup phenomenon is therefore usually a harmless, age-related change in the spine that rarely leads to serious problems. With targeted exercises and a mindful approach to looking after the back, symptoms can be managed well in most cases.
