Proximal Junctional Kyphosis

Abstract

CAUSES AND RISK FACTORS PJK may develop secondary to one or more of the following conditions: progressive deformity; disruption of the posterior ligament complex; vertebral compression fracture(s); instrumentation failure; degenerative disc disease, and/or facet violation.12-17 Several risk factors for development of PJK have been identified. These include advanced age (>55 years); fusion to the sacrum; combined anterior/posterior surgery; thoracoplasty; and upper instrumented vertebra at T1-T3. In addition, postoperative hypokyphosis or hyperkyphosis has been associated with increased risk of PJK.12-17 Studies have demonstrated that the risk of developing PJK is greatest within 2 years after surgery and that the risk decreases significantly after the 2-year period.12 The literature regarding the association between the length of the fusion, the location of the uppermost instrumented vertebrae, and the risk of PJK is less clear. Both greater and lower number of levels of fusion have been reported to be associated with an elevated risk for developing PJK.12-17 Similarly, termination of the construct at either the upper or lower thoracic levels have been reported as separate risk factors for PJK.12-17 The rates of and the risk factors for development of PJK are similar between instrumented fusion for adolescent versus and patients may be asymptomatic.1-4 However, severe cases may warrant surgical management. The primary indications for surgery in adults with degenerative scoliosis include: (1) progressive deformity; (2) development of poor spinal balance causing functional difficulties; (3) a large deformity threatening cardiopulmonary compromise; and (4) evidence of neurologic manifestations.5-7 In addition, the presence of persistent pain that fails to respond to standard nonoperative treatment and an unsatisfactory cosmetic appearance also may be considered indications for surgery.8-11 Proximal junctional kyphosis (PJK) has been increasingly recognized as a complication after long-segment instrumentation for the correction of kyphosis and scoliosis (Figures 1 and 2).12-17 PJK most commonly occurs at the site immediately above the uppermost instrumented vertebrae. PJK has been defined as a final proximal junctional sagittal Cobb angle greater than 10 degrees and a postoperative angle at least 10 degrees greater than the preoperative value (as measured between the lower endplate of the uppermost instrumented vertebra and the upper endplate of 2 vertebrae supra-adjacent).15 The incidence of PJK has been demonstrated to range between 17.0% to 39.0%, and the majority of cases seem to occur within 2 years after surgery.12-17 LEARNING OBJECTIVES: After participating in this CME activity, the spine surgeon should be better able to: 1. Describe the incidence, prevalence, and risk factors for proximal junctional kyphosis. 2. Identify the appropriate modality for management of proximal junctional kyphosis as a function of patient characteristics. 3. Explain the potential adverse effects and financial implications associated with proximal junctional kyphosis and alternatives to surgical management.