Table 5.

Risk factors identified in other studies on PJK

Study	Year of publication	Study population	Total number of patients	PJK incidence	Risk factor
Glattes et al. [2]	2005	Adults	81	26%	T3 UIV
Hollenbeck et al. [4]	2008	Adolescents	174	9%	None
Kim et al. [5]	2008	Adults	161	39%	Age > 55 years, combined anterior-posterior surgery
Kim et al. [6]	2005	Adolescents	193	26%	Thoracoplasty, preoperative thoracic hyperkyphosis (T5-T12 > 40), hybrid instrumentation
Kim et al. [7]	2007	Adolescents	410	27%	Male, thoracoplasty, preoperative thoracic hyperkyphosis (T5-T12 > 40)
Wang et al. [11]	2010	Adolescents	150	28%	Fusion below L2, use of pedicle screw at top of construct, thoracoplasty
Yagi et al. [12]	2011	Adults	157	20%	Fusion to S1, posterior segmental instrumentation, abnormal global sagittal alignment, CSVL correction > 5 cm

PJK = proximal junction kyphosis; UIV = upper instrumented vertebrae; CSVL = center sacral vertical line.