Connective tissue disease patients do not have higher rates of PJK compared with idiopathic EOS following growth friendly instrumentation.

Purpose: Proximal junctional kyphosis (PJK) is a condition frequently encountered in children with early onset scoliosis (EOS) undergoing growth-friendly instrumentation (GFI). Previous studies have identified risk factors but have not compared the rate of PJK between children with connective tissue disease (CTD) and idiopathic EOS (iEOS).

Methods: Retrospective review of a multicenter spine database was performed. Patients with EOS undergoing GFI with a minimum of 5 years follow-up were identified and isolated to those with CTD (Marfan, Loeys-Dietz, Ehlers-Danlos, Soto, and Larsen) and idiopathic etiologies. PJK was defined as requiring revision surgery or as having > 10 degree change in proximal junctional angle (PJA). Surgical factors and implant variables were recorded. Radiographic parameters and complication development were compared between groups.

Results: A total of 253 children (mean 5.7 years, 57% female) were identified (CTD:49, iEOS:204). A total of 58 patients developed radiographic PJK (23%) with only 11 (18.9%, 4% of total cohort) undergoing revision surgery at 5 years following implantation. There were no identified surgical factors or radiographic variables associated with the development of PJK. In comparing the CTD and iEOS cohorts, there was no difference in PJK (CTD:26.5%, iEOS:22.1%; P = 0.5). Additionally, there were no significant differences between groups for preoperative or 5-year follow-up radiographic parameters, although there was a trend toward greater increase in PJA from post-implant to 5 years in CTD patients (CTD: 2.5 ± 13.8° vs - 0.01 ± 9.9; P = 0.08). CTD and iEOS patients gained similar thoracic heights, 26.6 ± 20.7 mm vs 26.9 ± 21.7 mm (P = 0.8). There was no difference in overall complication rate but CTD patients experienced a greater number of complications/patient (3.1 vs 2.0; P = 0.004).

Conclusion: PJK is a pervasive complication in EOS, occurring in 23% of patients undergoing GFI. Having an underlying CTD did not increase the risk of PJK development within 5 years of treatment.