Kissing Spine, also known as Baastrup’s disease, is a recognized cause of chronic lower back pain resulting from an anatomical abnormality in the vertebrae. This condition involves two or more adjacent bony projections in the spine making contact, leading to inflammation and discomfort. Kissing Spine represents a common degenerative condition, particularly among older individuals, causing significant back discomfort. Understanding the mechanics of this spinal issue is the first step toward effective management.
Understanding the Anatomy of the Spine
The spine is composed of individual bones called vertebrae, each featuring several bony protrusions. The spinous processes are the slender, backward-pointing projections that can be felt just beneath the skin along the center of the back. These processes typically have a protective space between them, filled with ligaments and soft tissue.
In a person with Kissing Spine, the space between two or more adjacent spinous processes narrows significantly, causing the bones to approximate or touch completely. This abnormal contact, or “kissing,” leads to mechanical irritation, inflammation, and often the formation of a false joint, known as a pseudoarthrosis, between the two bones. The condition most frequently occurs in the lumbar spine, or lower back, with the segment between the fourth and fifth lumbar vertebrae (L4-L5) being the most common site for this interspinous contact.
Primary Factors Leading to Development
The development of Kissing Spine is largely attributed to degenerative changes in the spine, which are an expected part of the aging process. As the intervertebral discs between the main bodies of the vertebrae begin to wear down and lose height, the overall vertical space decreases, causing the spinous processes to move closer together. This reduction in disc height is a primary mechanism that encourages the approximation of the adjacent bones.
Postural changes also play a significant role, particularly excessive lordosis, which is an exaggerated inward curve of the lower back. This increased arching puts mechanical pressure on the posterior elements of the spine, forcing the spinous processes into closer contact and causing repetitive strain on the ligaments between them. Over time, this chronic mechanical stress can cause the interspinous ligaments to degenerate, further removing the cushioning between the processes.
Repetitive strain from certain activities can also contribute, especially in athletes who frequently perform movements that involve hyperextension of the spine, such as gymnasts. This repeated movement accelerates the wear and tear on the interspinous tissues, leading to degenerative hypertrophy, where the bony surfaces flatten and enlarge in response to the friction. While less common, a history of spinal injury or trauma can sometimes initiate the degenerative cascade that results in the condition.
Recognizing the Signs and Confirmation
The primary symptom associated with Kissing Spine is pain localized to the midline of the back, which may sometimes radiate slightly up or down the spine. A distinguishing feature of the pain is that it typically worsens when the back is extended or arched backward, such as when standing upright for long periods or walking. Conversely, many individuals experience relief when they round their back or flex forward, which temporarily separates the bony processes.
Physical examination often reveals tenderness when a doctor presses directly on the affected area of the spine. To confirm the diagnosis, a physician relies on imaging studies, with X-rays being the standard initial tool. Lateral view X-rays clearly show the close approximation or contact of the adjacent spinous processes.
While X-rays confirm the bony contact, Magnetic Resonance Imaging (MRI) is often used to gain a more detailed view of the soft tissues. An MRI can identify inflammation, fluid accumulation (interspinous bursitis), and the formation of any cysts in the space between the bones, providing a more sensitive assessment of the overall degenerative process. This comprehensive approach helps differentiate Kissing Spine from other causes of low back pain.
Managing and Treating the Discomfort
Treatment for Kissing Spine generally follows a stepwise approach, beginning with conservative therapies designed to alleviate pain and restore function. The first line of defense involves anti-inflammatory medications, such as non-steroidal anti-inflammatory drugs (NSAIDs), to reduce the pain and inflammation caused by the bony contact. Physical therapy is a major component of conservative management, focusing on strengthening the core muscles to support the spine and correcting posture to minimize excessive lordosis.
Activity modification is also recommended, which involves avoiding activities that exacerbate the pain, particularly those that require spinal extension or arching. If conservative methods do not provide adequate relief, the next step involves interventional procedures. This often includes fluoroscopically guided corticosteroid injections, where a mixture of local anesthetic and a steroid is injected directly into the space between the affected spinous processes. These injections target the site of inflammation and can provide pain relief for several months.
For the minority of patients whose symptoms persist despite conservative and interventional treatments, surgical options may be considered. Surgical decompression aims to physically increase the space between the kissing processes. Techniques include an osteotomy, which involves removing a portion of the spinous process, or the insertion of a specialized device as a spacer between the bones. These surgical interventions are reserved for severe, persistent cases where less invasive measures have failed.