Predicting the Occurrence of Postoperative Distal Junctional Kyphosis in Cervical Deformity Patients

Abstract

BACKGROUND Distal junctional kyphosis (DJK) development after cervical deformity (CD)-corrective surgery is a growing concern for surgeons and patients. Few studies have investigated risk factors that predict the occurrence of DJK. OBJECTIVE To predict DJK development after CD surgery using predictive modeling. METHODS CD criteria was at least one of the following: C2-C7 Coronal/Cobb > 10°, C2-7 sagittal vertical axis (cSVA) > 4 cm, chin-brow vertical angle > 25°. DJK was defined as the development of an angle <−10° from the end of fusion construct to the second distal vertebra, and change in this angle by <−10° from baseline to postoperative. Baseline demographic, clinical, and surgical information were used to predict the occurrence of DJK using generalized linear modeling both as one overall model and as submodels using baseline demographic and clinical predictors or surgical predictors. RESULTS One hundred seventeen CD patients were included. At any postoperative visit up to 1 yr, 23.1% of CD patients developed DJK. DJK was predicted with high accuracy using a combination of baseline demographic, clinical, and surgical factors by the following factors: preoperative neurological deficit, use of transition rod, C2-C7 lordosis (CL)<−12°, T1 slope minus CL > 31°, and cSVA > 54 mm. In the model using only baseline demographic/clinical predictors of DJK, presence of comorbidities, presence of baseline neurological deficit, and high preoperative C2-T3 angle were included in the final model (area under the curve = 87%). The final model using only surgical predictors for DJK included combined approach, posterior upper instrumented vertebrae below C4, use of transition rod, lack of anterior corpectomy, more than 3 posterior osteotomies, and performance of a 3-column osteotomy. CONCLUSION Preoperative assessment and consideration should be given to these factors that are predictive of DJK to mitigate poor outcomes.

A Review of Indications, Surgical Technique, and Outcomes for the Cervical Pedicle Subtraction Osteotomy

“…Passias et al have also determined that the following surgical factors are associated with DJK risk: combined approach, posterior upper instrumented vertebrae below C4, use of transition rod, lack of anterior corpectomy, more than three posterior osteotomies, and performance of a 3-column osteotomy. 24…”

Pediatric cervical kyphosis in the MRI era (1984–2008) with long-term follow up: literature review

“…Various techniques of ventral and dorsal approaches to the adult cervical spine have been described [3, 10, 13-15, 32, 33, 40]. In a recent review by the International Spine Study Group, 13 sites with adult cases were studied to predict the occurrence of postoperative distal junctional kyphosis in cervical deformity patients who underwent surgical procedures [28]. There was a 23.1% prevalence of distal junctional kyphosis in 117 adult patients with cervical deformity.…”

“…No long-term pediatric results are available. Recent review articles and meta-analysis in adults have been made in an effort to better understand cervical deformity, but the weakness is a crossstudy analysis, differences in outcome measures, and surgical approach [3,10,11,18,28,37]. The deformity may result from posterior cervical instability from laminectomy as well as trauma.…”

Sagittal balance of the cervical spine

“…DJK has been defined as a loss of radiographic alignment at one or two levels distal to the lowermost instrumented vertebra (LIV) and is associated with adjacent level failure, instrumentation failure, and spondylolisthesis. 62 A study by Passias and colleagues demonstrated a 1-yeay postoperative rate of 23.1% for DJK. 62 DJK occurred most commonly at 3 months postoperative and patients with DJK had significantly more severe cervical malalignment at baseline, as measured by T1S-CL, CL, cSVA, C2-T3 angle, and C2 slope.…”

“…62 A study by Passias and colleagues demonstrated a 1-yeay postoperative rate of 23.1% for DJK. 62 DJK occurred most commonly at 3 months postoperative and patients with DJK had significantly more severe cervical malalignment at baseline, as measured by T1S-CL, CL, cSVA, C2-T3 angle, and C2 slope. 62 Since DJK is a critical complication of cervical deformity correction, there are a few DJK prevention methods that include the use of medications to strengthen bone density such as teriparatide, appropriate selection of the LIV in relation to the curve apex, and ligament augmentation.…”