Adult isthmic spondylolisthesis.

Isthmic spondylolisthesis is present in a small subset of the adult population. Although the incidence of low back pain in these persons is similar to that of the general population, both pars interarticularis defect and forward slip can serve as unique pain generators. Neurologic symptoms may result from nerve root impingement related to the pars defect or degenerative changes associated with the deformity. Most symptomatic cases are successfully managed nonsurgically, but patients with intractable pain or neurologic symptoms may benefit from surgical decompression and stabilization. Surgical intervention has shown >80% success in appropriately selected patients, with a low incidence of complications. Surgical techniques include decompression, posterolateral fusion, anterior lumbosacral interbody fusion, and circumferential fusion methods. Circumferential fusion results in improved fusion rates and, in some studies, superior clinical outcomes. The choice of procedure is generally guided by the patient's radiographic and clinical findings as well as risk-benefit considerations.