Assessment of malunion in spinal fusion

Pseudarthrosis, or non-union, is a relatively common and occasionally difficult problem for the spine surgeon to treat. It often appears weeks of months after the initial surgery, and presents with pain or neurologic deterioration after a period of improvement. Pseudarthrosis is defined as the persistence of a motion segment after attempted bony fusion, either at the interbody space or the posterolateral spine. The causes of non-union can be difficult to ascertain and are often multifactorial; they can include use of nicotine or certain pharmacologic agents; patient co-morbidities; and osteoinductive properties of the bone used for fusion.Pseudarthrosis may be difficult to diagnose, and often requires the use of several radiologic studies, including reformatted CT scan. The gold standard for determining if pseudarthrosis exists, open exploration, is usually unfeasible. Treatment options for symptomatic pseudarthrosis include operative intervention, either posteriorly or anteriorly (or both), and fusion rates can be enhanced with the use of internal fixation, bone morphogenic protein, and electrical stimulation. The best treatment for pseudarthrosis remains prevention. This review discusses the pathophysiology, diagnosis, prevention and treatment of spinal pseudarthrosis.