查看文章

Adult spinal deformity (ASD) surgery has made great progresses in the past decades but despite the improvement in surgical techniques and the respect of sagittal alignment rules, proximal junctional kyphosis (PJK) is still the most important postoperative mechanical complication not fully understood by the clinicians. PJK is one of the main causes for revision surgery. Understanding the reason for PJK could help to decrease its occurrence by a better surgical planning. ¹ PJK is defined as a change of at least 10 degrees in the first motion segment over the upper instrumented vertebra caused by the failure of either the vertebra, the soft tissue, or the bone-implant interface in thoracolumbar fusion surgeries. ¹ This event can occur in the early postoperative period (within 6 weeks) or even after months from the fusion surgery. It is reported that the incidence of PJK varies from 20 to 60% of the cases. 2-5 When the junctional kyphosis becomes symptomatic, it is then called proximal junctional failure (PJF) and it might require revision; the most common reported causes of failure are vertebral fracture, soft tissue failure, and screw pull-out." Several studies have analyzed the risk factors associated with these complications and correlations were found both with patient's related factors and with the postoperative sagittal alignment achieved. The most important patient-related factors are the magnitude of the deformity, age, body mass index (BMI), bone mineral density, and paravertebral muscle quality.? Concerning age, it is reported that patients older than 55 years have higher risk of developing a PJK8, 9; patients with higher BMI might have greater …