Isthmic spondylolisthesis results when a fracture gap at the pars interarticularis (the junction of the upper and lower lumbar spine joints of one vertebra) widens. Widening of the gap leads to the fifth lumbar vertebra shifting forward on the part of the pelvic bone called the sacrum; this is known as "slippage."
Degenerative spondylolisthesis results when wear and tear breaks down the pars interarticularis, causing slippage of one vertebra on another. This is more common in adults and most commonly occurs between the fourth and fifth lumbar vertebrae.
- The primary symptom is pain related to nerve root irritation, which can occur in the lower back, buttocks, or legs.
- Numbness or a tingling sensation of the legs
Post-treatment "maintenance" exercises like truncal core muscle strengthening (pilates or yoga) may be prescribed to condition the muscles and minimize reinjury.
- Anti-inflammatory drugs
- Brace wear
- Activity modifications
- Physical therapy treatment that incorporates truncal core strengthening exercises (the therapist will caution the patient on avoiding hyperextension maneuvers and excessive abdominal "crunches")
If the pain, spasm, or slippage increases despite conservative management, then the surgeon may discuss spinal fusion with the patient:
- For a majority of children and adults, fusing the fifth lumbar vertebra to the sacrum (the most common vertebrae involved in adolescents with spondylolisthesis) is the preferred surgical option.
- The fusion involves removing the loose bony fragments and placing bone graft that will lead to the 2 vertebrae “fusing together" to prevent any further slippage. Specially designed screws and rods may be needed to hold the vertebrae in place to help the two bones fuse together.
- A perforated, hollow cylinder called a "cage" is sometimes required. The "cage" is filled with bone matter and placed in the disc space between the two vertebrae to increase the likelihood of fusion.
Bones may be realigned depending on how much one vertebra has slipped forward on the other. The most important steps are restoring stability and making sure the nerves have no pressure on them.