Decompression

Introduction

Lumbar spine disorders and the disabling pain associated with these conditions are associated with significant healthcare resource use and costs in the United States. Of these patients, an estimated 3% with back pain will require surgical intervention. Spine surgery in this patient population continues to be more prevalent, accelerated by the increasing number of aging patients. These patients are afflicted by a range of degenerative pathology for failed back surgery syndrome (adjacent segment disease [ASD], pseudarthrosis, and same-level recurrent stenosis) resulting in the need for revision surgery.

Revision surgery has its own intrinsic technical challenges and is exponentially more challenging in our aging population. Surgery can be confounded by patients with a long duration of symptoms and significant underlying medical comorbidities. Conditions such as diabetes or smoking have implications on bone biology and recovery. The indications for revision surgery may necessitate a range of interventions from a revision decompression to an extensive deformity correction. The reoperation rates for lumbar canal stenoses as a result of inadequate decompression or instability range from 7% to 12%, depending on the initial index surgery. The majority of published studies have been retrospective case series with varying definitions of successful outcome. Some are published reports of provider-defined outcomes rather than validated patient-reported outcome metrics. Hence effectiveness and long-term outcomes in elderly patients undergoing revision lumbar surgery remain unknown.

Indications for revision lumbar decompression can include ASD (owing to prior lumbar fusion) with disc degeneration, spondylolisthesis, or adjacent segment stenosis. These patients can present with recurrent mechanical low back and radicular pain localizing to the adjacent segment. Moreover, same-level recurrent stenosis from a prior lumbar laminectomy with persistent symptoms of claudication may occur. In addition, patients can develop coronal and sagittal deformities in the setting of prior surgery. Development of these deformities may be accelerated with conditions such as osteoporosis and osteomyelitis. Therefore it is important to apply the principles of diagnosis and pathophysiology in determining the optimal treatment needed as well as the appropriate surgical technique that is indicated.

Diagnosis and Indications for Surgery

Degenerative lumbar conditions can present clinically with pain, neurological compromise, spinal deformity, or a combination of all three. The etiology may stem from the previous surgical level, the adjacent level, or from a global combination of sagittal/coronal imbalance. Eliciting an accurate account of the location, timing, and inciting events for the chief complaint is important, to better understand the etiology and natural history of the disease process. The physical examination is a critical part of the assessment and should include a complete assessment of motor function, sensation, and reflexes. Evaluating for long tract signs may exclude upper motor neuron pathologies. Examination of the patient’s overall posture is necessary to evaluate spinal alignment in both the coronal and sagittal planes. Compensatory findings such as hip flexion contractures could be identified in the setting of suspected spinal deformity. Diagnostic imaging may include upright and bending films, computed tomography (CT) imaging, magnetic resonance imaging (MRI), or technetium bone scans to identify areas of increased bone turnover. These concordant findings may help support indications for surgical treatment of pseudarthrosis, fracture, ASD, instability, deformity, infection, and even device irritation.