Relook into the Risk Factors of Proximal Junctional Kyphosis in Early Onset Scoliosis Patients: Does the Location of Upper Instrumented Vertebra in Relation to the Sagittal Apex Matter?

Abstract

Objective Growing rods surgery is the mainstay of treatment for early‐onset scoliosis (EOS) while proximal junctional kyphosis (PJK) is one of the most commonly reported postoperative complications. We sought to investigate the impact of the location of upper instrumented vertebra (UIV) in relation to the sagittal apex on proximal junctional kyphosis in EOS after traditional growing rods (GRs) treatment. Methods A total of 102 EOS patients who received traditional growing rods treatment with a follow‐up of at least 2 years between 2009 and 2020 were retrospectively reviewed. Radiographic measurements were performed before and after the index surgery and at the latest follow‐up. We investigated the coronal Cobb angle and spinopelvic parameters of the whole spine. The location of the UIV, apex, lower instrumented vertebra (LIV), inflection vertebra (IV), the number and distance of UIV‐apex, LIV‐apex and IV‐apex were also recorded. Risk factors for PJK were analyzed by logistic regression analysis. Results PJK was observed in 21 patients (20.6%) during the follow‐up period. The PJK group showed a younger age at the index surgery (5.9 vs. 7.1 years, P = 0.042), more lengthening procedure times (5.0 vs. 4.0, P = 0.032), larger preoperative coronal Cobb angle (82.0 vs. 75.6°, P = 0.038), higher correction rate (51.2% vs. 44.4%, P = 0.047) and larger postoperative proximal junctional angle (PJA) (13.9 vs. 5.5°, P < 0.001) than the non‐PJK group. The ratio of the number and distance from UIV‐apex to IV‐apex also differed significantly between the two groups. The logistic regression revealed that age at the index surgery ≤ 7 years, the ratio of the number from UIV‐ apex to IV‐ apex ≤ 0.6 and the ratio of the distance from UIV‐ apex to IV‐ apex ≤ 0.6 were independent risk factors for postoperative PJK. Conclusion Besides younger age, a closer location of UIV relative to the sagittal apex is identified to be an independent risk factor of postoperative PJK. Selection of UIV at a relatively farther location away from the sagittal apex might help prevent occurrence of PJK.

Factors Related to Proximal Junctional Kyphosis and Device Failure in Patients with Early-Onset Scoliosis Treated with a Traditional Dual Growing Rod: A Single Institution Study

“…A younger age at the time of the index surgery and longer procedure times have also been shown to be associated with the incidence of PJK [ 20 ]. In this study, the rate of PJK was 54.2% (19 of 35 patients).…”

“…PJK is a common alignment-related complication in patients with EOS undergoing TGR [15,16], and an incidence rate of 12%-56% has been reported in previous studies [17][18][19]. The difference rate of PJK in various studies has been attributed to differences in the study sample, EOS etiology, surgical procedure, fixation instrumentation, and follow-up period [17,20,21]. Several risk factors have also been reported for PJK, including the location of the upper or lower instrumented vertebra, proximal thoracic scoliosis of >40°, a main thoracic kyphosis of >60°, a higher correction rate, and location of the UIV in relation to the sagittal apex [17,18,20,[22][23][24].…”

Acute unexplained T1-T2 fracture-dislocation following posterior instrumentation and fusion for paralytic scoliosis

“…This is a common finding in spine surgery in the elderly [ 8 ], especially when the sagittal balance is overestimated, or the proximal instrumentation level is not adequate. It is also a known complication in severely involved paralytic patients with poor muscle tone, if the upper instrumented vertebra is short of the apex of the thoracic kyphosis [ 9 , 10 ].The current report relates to a pediatric but severely involved CP patient. However, like in almost all patients in this category, posterior instrumentation extended proximally to T2 in an attempt to decrease the risk of PJK.…”

Implant-Related Complications Do Not Interfere with Corrections with the Shilla Technique in Early Onset Scoliosis: Preliminary Results

“…Miladi et al found fewer mechanical complications with fusionless double ends technique using hooks instead of transpedicular screws for proximal fixation in a growth-friendly scoliosis surgery [ 29 ]. Other factors that can affect the success rates of treatment include the severity of the condition, the age of the patient, and the presence of any underlying conditions especially in neuromuscular origin [ 28 , 31 ] Further research is needed to determine the success rates of different treatment options for proximal junctional problems in EOS.…”