Spondylolisthesis in children: Cause, natural history, and management

Spondylolisthesis is an infrequent sequelae of spondylolysis. It can be progressive and cause pain. In adolescents, the common subtypes are dysplatic and isthmic. The etiology of spondylolisthesis is unknown, although there is a genetic predisposition, and repetitive trauma is strongly implicated. The literature does not provide good data to allow prediction of which patients with spondylolysis will have progressive slippage. Standing spot lateral radiographs taken in a standardized manner are essential for analysis of the deformity and documentation of progression. Patients with dysplastic posterior elements have a higher risk of slip progression. Most slips are not severe and once growth is complete are unlikely to progress. There is no proven increased rate of disability in patients with mild spondylolisthesis. The role of the treating physician is to identify the nature of the slip, treat the symptoms, and monitor the patient for progression. The goal of nonoperative treatment is pain relief and return to full function. In the absence of conclusive studies, the current consensus is to treat symptomatic, mild-to-moderate spondylolisthesis with activity modification, physical therapy, stretching, and exercises, although no scientific data are available regarding the outcome of this treatment. Bracing is thought to be helpful to control pain in patients with severe symptoms. In certain cases, the symptoms are persistent despite nonoperative treatment, or the slip is found to be progressive, and surgical fusion is indicated. Slips of greater than 50% are thought to be at high risk for progression to spondyloptosis, and fusion without preliminary nonoperative treatment is recommended in children who present with this degree of deformity. In situ posterolateral fusion is the recommended treatment for slips of up to 50%. Moderate-to-severe slips cannot be predictably stabilized by posterolateral in situ fusion, and are at higher risk for pseudoarthrosis and progressive deformity. Combined anterior and posterior fusion with cast immobilization, or deformity reduction and instrumented fusion, may be needed in these cases. Techniques for instrumented reduction are evolving, but currently are associated with higher rates of temporary or permanent nerve root injury. Instrumentation for in situ stabilization of severe slips is widely used in an attempt to improve fusion rates, but long term studies are not yet available to document the efficacy of this approach. Further studies are needed to identify the patient with a high risk for slip progression, so that they can be followed more closely. In patients with severe spondylolisthesis, studies comparing the results of combined anterior and posterior fusion to fusion with instrumented reduction are needed.