Correlations of proximal junctional kyphosis with radiographic measurements, spinopelvic parameters, and health-related quality of life in Lenke type V adolescent idiopathic scoliosis

OBJECTIVES: This study aims to investigate the effects of radiographic measurements, spinopelvic parameters, and Scoliosis Research Society-22r (SRS-22r) subscales on proximal junctional kyphosis (PJK) in patients with Lenke type V adolescent idiopathic scoliosis operated with only a posterior all-pediclescrew instrumentation technique. PATIENTS AND METHODS: Between January 2011 and March 2019, data of 115 patients (17 males, 98 females; mean age: 14.6±2.9 years; range, 10 to 18 years) with Lenke type V AIS who were operated with posterior fusion were retrospectively analyzed. Proximal junctional angle (PJA) was measured as a Cobb angle (CA) between the inferior endplate of the upper instrumented vertebra and the superior endplate of the second suprajacent vertebra. A ≥10° PJA and being ≥10° greater than its preoperative value was defined as PJK. Radiographic measurements, SRS-22r scores, and correlations with the PJA were evaluated for PJK and non-PJK groups. RESULTS: The prevalence of PJK was 35.6%. There were statistically significant differences between the groups in terms of preoperative CA (p=0.002), preoperative thoracic kyphosis angle (TKA) (p<0.001), postoperative TKA (p=0.001), PJA (p<0.001), postoperative pelvic tilt (p=0.038), preoperative pain (p=0.005), preoperative self-image (SI) (p=0.045), preoperative subtotal score (p=0.006), preoperative total score (p=0.007), and sex distribution (p=0.002). No statistically significant differences were detected for other parameters (p>0.050). Positive correlations were found between PJA and preoperative TKA (p=0.042), postoperative TKA (p=0.002), preoperative sagittal balance (SB) (p=0.015), preoperative SI (p=0.012), postoperative SI (p=0.032), postoperative mental health (p=0.011), postoperative subtotal score (p=0.018), postoperative total score (p=0.014), and postoperative sacral slope (SS) (p=0.015). A negative correlation was found between PJA and preoperative satisfaction (p=0.044). CONCLUSION: The occurrence of PJK is multifactorial, including clinical, surgical, and radiographic factors. Male patients with higher pre and postoperative TKA, preoperative SB, and postoperative SS and patients with lower satisfaction have a higher risk of PJK development.