Low-grade isthmic/lytic spondylolisthesis in adults.

Three basic classification schemes have been developed to categorize spondylolisthesis, the slippage or forward displacement of one vertebra over another. Two rely on radiographic appearance, and the third stresses the developmental aspect of the pathology. The pathology is relatively rare in individuals younger than 18 years, appears to be influenced by race, and is found more frequently in males than females and in patients with symptomatic low back pain. Lytic spondylolisthesis occurs more frequently at certain spinal levels, and certain sports activities have been implicated in its development. The etiology remains unclear, but hereditary factors are unlikely with no evidence of the lytic defect in newborns. Recent research indicates that the architecture of the pelvis may be an important parameter. Some have postulated that the underlying pathomechanical event is a fracture, either acute or secondary to fatigue. Once the pars defect has been created, anatomic and biomechanical forces conspire to prevent healing of the fracture and create a spondylolisthesis. Although mechanical considerations are likely most significant, genetic considerations have also been discussed. All the imaging modalities play useful roles in defining the pathoanatomy, including diskography. Patients typically report symptoms as back pain and/or neurologic symptoms; however, these symptoms can have other causes even though a spondylolisthesis is present. A thorough history and physical examination, along with the radiographic investigations, are essential to determining proper treatment. Nonsurgical options are activity modification, bracing, physical therapy, and intervention in the form of medications or injections. Use of muscle relaxers and narcotics may be appropriate for managing initial acute pain. Surgical options are direct repair of the pars defect, decompression, fusion, or a combination of these procedures. The various techniques of pars repair are recommended only for patients younger than 30 years. Although decompression alone may be suitable in some situations, decompression with fusion is more standard, certainly when instability and low back pain exist.