The terms referring to these pathologies derive from ancient Greek. Spondylolysis sphondylos + lysis (vertebrae + rupture) and Spondylolisthesis sphondylos + olisthanein (vertebrae + falling) mean respectively, the fracture and the forward displacement of one vertebra relative the vertebra below.
Spondylolisthesis arises when mechanical pressure to the spine at the lumbo-sacral region induces the sliding of one vertebra towards the anterior, abdominal side of the body. It can also occur consequent to the weakening of the spine ligaments that keep the vertebrae aligned, making the spine vulnerable to displacement during movement and weight bearing. The disease is most common in women and ageing people. The alteration of the vertebral alignment may compress the nerves and cause neurological symptoms.
Spondylolysis is the stress fracture of a vertebra more often affecting the 5th lumbar vertebra. In ageing people spondylolisthesis ensues from degeneration of the disk, its thinning and possibly herniation, which reduces the intervertebral space. Consequent to vertebral mal-alignment the pressure on the vertebra causes the fracture of the pars interarticularis, leading to spondylolytic spondylolisthesis. This alteration reduces the spinal canal (stenosis) and puts pressure on the spinal cord. Spondylolytic spondylolisthesis may occur as a consequence of an older fracture of the pars interarticularis in adolescence, which later in life can lead to disk degeneration and forward sliding of the vertebra or spondylolisthesis.
Grading of spondylolisthesis is done according to the Meyerding classification, based on the percentage of the overhanging part of the superior vertebra relative to anteroposterior column of the adjacent inferior vertebral body:
Grade I: 0-25%
Grade II: 26-50%
Grade III: 51-75%
Grade IV: 76-100%
Grade V: >100% (spondyloptosis; most severe of translational spine injuries)
Spondylolisthesis can have various origins.
Genetics: hereditary congenital vertebrae malformation having thin bone structure, which can be aggravated with rapid growth.
Overuse: Intensive sport activities that put extreme pressure on the spine (gymnastic, weight lifting) or that involve hyperextension of the lower spine (baseball, golf, cricket).
Generally, the causes are divided into the following types:
Type I congenital, abnormal development of the facet joints that facilitate forward translation of the vertebrae in adolescence
Type II isthmic spondylolisthesis caused by a stress fracture of the pars interarticularis
Type III degeneration of the facet joints due to arthropathy in older people
Type IV traumatic injury to the facet joints or pars interarticularis
Type V Instability of the facet joints of iatrogenic origin (facetectomy surgery).
Spondylolysis is essentially a stress fracture caused by repeated strains to the lower back.
Potential risk factors to acquire spondylolisthesis and spondylolysis are:
Adolescence (isthmic spondylolysis)
Anatomical predisposition (facet joint malformation, spine lordosis)
Congenital joint laxity
Sports involving repetitive spine hyperextension, rotation or flexion-extension may develop pars defects (gymnastics, football, weightlifting, judo)
Patients often visit a specialist when spondylolisthesis has degenerated to the extent of producing back pain and neurological symptoms due to the advanced compression of the nerves (radiculopathy), or to the spinal cord by disk herniation.
Spondylolisthesis progressively leads to low back pain, muscle spasms, stiffening and weakening of the muscles in the lower back and hamstrings. Additional neurologic symptoms include numbness, tingling and pain, particularly with long standing and walking. In adolescents symptoms may manifest during a growth spur.
With spinal trauma symptoms of spondylolisthesis become acute and more likely neurological involving bladder/bowel function and claudication due to compression of the cauda equina.
Symptoms of spondylolysis include low back pain and stiffness. Pain is aggravated with activity. With time, pain may radiate down to one or both legs. During the healing process of the fracture, tissue growth may interfere with the nerve exit at the foramen thus worsening neurological symptoms.
Medical history and physical examination are essential for the diagnosis of spondylolysis and spondylolisthesis. Palpation of the spine and observing the patient during spinal bending and twisting may trigger pain and help the detection of anatomical abnormalities.
X-ray of the lower spine is the easiest method to diagnose both spondylolysis and spondylolisthesis. This will reveal the presence of a fracture or the sliding of one vertebra relative to the spine. The doctor will measure the anatomical changes to assess the gravity of the condition. If these pathologies are complicated by neurological symptoms, a CT or MRI scan will allow to visualise degenerative changes of the disks, spinal canal, spinal cord to address a suitable therapy.
Electromyography is also used to assess neurological changes such as radiculopathy or vertebral canal stenosis, which may occur as a consequence of spondylolisthesis.
Conservative treatment is the standard initial approach to address spondylolisthesis. This will improve the symptoms but not reverse vertebral sliding. The strategy focuses on the interruption of any strenuous physical activities and the administration of analgesics and non-steroidal antiinflammatory drugs (NSAIDs) or steroid injection in the local epidural space to ease pain. Ongoing degeneration in the alignment of the spine will be monitored regularly by repeated X-rays in standing position. Although controversial, bracing is also adopted by some orthopaedic surgeons in form of thoraco-lumbosacral spinal orthosis or modified Boston Brace for 3-6 months. These are recommended only in isolated spondylolysis and not spondylolisthesis. Physical therapy usually begins when the acute symptoms have subsided paying particular attention to strengthen the core muscles of the spine and abdomen in support of the affected region and stretching of the lower sacral spine.
If conservative treatment over 3 to 12 months fails to improve pain and neurological symptoms, or when spondylolisthesis is aggravated with further displacement of the vertebrae over 50%, in Type 1 and 2 slips, with a severe neurological component, or after traumatic spondylolisthesis, surgery is required. The preferred method of choice is a spinal fusion of the lumbar vertebra and the sacrum. In case of both degenerative spondylolisthesis and spondylolytic spondylolisthesis the aim of surgery is to relieve the pressure to the nerves with a laminectomy and perform a spinal fusion to restore alignment and stability of the spine. For a detailed description of surgical methods please refer to the pathology Disk herniation.
Working with isotonic and isometric exercises to strengthen the deep abdominal muscles and the muscles of the trunk surrounding the spine provide beneficial stability to the vertebrae to delay further misalignment, aggravating the spondylolisthesis. Stretching exercises alleviate the pressure to the lower back when flexing or extending the spine. In addition, the following measures are recommended:
Antilordotic postures to reduce the curvature of the lumbar spine
In the young athletic population preventing spondylolisthesis translates into avoiding strenuous physical activities and bending the back in hyperextension. In the elderly it is key to maintain strong core muscles to support the spine and delay spinal degeneration caused by ageing. Educating both groups on the risks of developing these conditions by adopting proper movements and postures while exercising is also critical.