Predictive Factors for Proximal Junctional Kyphosis in Long Fusions to the Sacrum in Adult Spinal Deformity
Study Design. A retrospective studyObjective. To assess the mechanisms and the independent risk factors associated with proximal junctional kyphosis (PJK)in patients treated surgically for adult spinal deformity with long fusions to the sacrum.Summary of Background Data. The occurrence of PJKmay be related to preoperative and postoperative sagittal parameters. The mechanisms and risk factors for PJK in adultsare not well-defined.Methods. A consecutive patients who underwent long instrumented fusionsurgery (≥6 vertebrae) to the sacrum with a minimum of 2 years follow-up were retrospectively studied.Risk factorsincluded patient factors, surgical factorsand radiographic parameters such as thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic tilt (PT), and pelvic incidence (PI).Results. Ninety consecutive patients (mean age: 64.5 years) met inclusion criteria. Radiographic PJK occurred in 37of the90 (41%) patients with a mean follow-up of 2.9 years. The most common mechanism of PJK was fracture at the upper instrumented vertebra (UIV)in 19 (51%) patients. Twelve (13%) patients with PJK were treated surgically with proximalextension of the instrumented fusion. Preoperative TK >30°, preoperative proximal junctional angle (PJA) >10°, change in LL >30°,and PI >55° were identified as predictors associated with PJK. Achievement of ideal global sagittal realignment (SVA <50mm, PT <20°,and PI-LL <±10°) protected against the development ofPJK(19% vs. 45%).Amultivariate regression analysisrevealed changesin LL >30° and preoperative TK >30° were the independent risk factors associated with PJK.Conclusion. Fracture at the UIV was the most common mechanism for PJK. Change in LL >30° and preexisting TK >30° were identified as independent risk factors. Optimal postoperative alignment of the spine protectsagainst the development of PJK. A surgical strategy to minimize PJK may include preoperative planning forreconstructions with a goal of optimal postoperative alignment.
- [Show abstract] [Hide abstract] ABSTRACT: Severe thoracic kyphosis caused by pathologic fractures often needs to be corrected by resection of the collapsed vertebral body, reconstruction of the anterior spinal column, and correction of the kyphosis with long-segment fixation. The resection of this pathologic bone functions essentially as a vertebral column resection. With the advent of minimally invasive technology, the powerful corrective forces afforded in open cases can be applied using a less invasive approach. In this article, we describe a mini-open posterior technique for thoracic kyphosis via a vertebrectomy and cantilever technique. Two patients underwent kyphosis correction via mini-open vertebrectomy. One patient was corrected from 92 degrees to 65 degrees, and the second patient was corrected from 70 degrees to 53 degrees. Both patients underwent a mini-open approach. Cantilever correction was accomplished over an expandable cage with a minimally invasive pedicle screw system. We describe our technique of mini-open vertebral column resection and kyphosis correction in the thoracic spine.
- [Show abstract] [Hide abstract] ABSTRACT: Study Design: Retrospective review. Objective: To study time to development, clinical and radiographic characteristics, and management of proximal junctional kyphosis (PJK) following thoracolumbar instrumented fusion for adult spinal deformity (ASD). Summary of Background Data: PJK continues to be a common mode of failure following ASD surgery. Although literature exists on possible risk factors, data on management remains limited. Methods: A retrospective review of medical records of 289 consecutive ASD patients who underwent posterior segmental instrumentation incorporating at least five segments was conducted. PJK was defined as proximal kyphotic angle >10[degrees]. Results: PJK occurred in 32 patients (11%) at a mean follow-up of 34 months (1.3-61.9+/-19 mo). 16 (50%) patients were revised (mean 1.7 revisions, range: 1-3) at a mean follow up of 9.6 months (range: 0.7-40 mo); primary indications for revision were pain (n=16), myelopathy (n=6), instability (n=4), and instrumentation protrusion (n=2). Comparison of pre- and post-index surgery radiographic parameters demonstrated significant improvement in mean lumbar lordosis (LL) (24[degrees] vs. 42[degrees], P<0.001), pelvic incidence (PI)-LL mismatch (30[degrees] vs. 11[degrees], P<0.001), and pelvic tilt (PT) (29[degrees] vs. 23[degrees], P<0.011). The mean T5-T12 kyphosis worsened (30[degrees] vs. 53[degrees], P<0.001) and the mean global sagittal spinal alignment failed to improve (9.6 cm vs. 8.0 cm, P=0.76). There was no apparent relationship between the absolute PJK angle and revision surgery (P>0.05). Conclusions: The patients in this series who developed PJK had substantial pre-operative positive sagittal malalignment that remained inadequately corrected following surgery, likely resulting from a combination of inadequate surgical correction and a significant compensatory increase in thoracic kyphosis. In the absence of direct relationship between a greater PJK angle and worse clinical outcome, clinical symptoms and neurological status rather than absolute reliance on radiographic parameters should drive the decision to pursue revision surgery.
- [Show abstract] [Hide abstract] ABSTRACT: Proximal junctional kyphosis (PJK) is a common radiographic finding following long spinal fusions. Whether PJK leads to negative clinical outcome is currently debatable. A systematic review was performed to assess the prevalence, risk factors, and treatments of PJK. Literature search was conducted on PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials using the terms 'proximal junctional kyphosis' and 'proximal junctional failure'. Excluding reviews, commentaries, and case reports, we analyzed 33 studies that reported the prevalence rate, risk factors, and discussions on PJK following spinal deformity surgery. The prevalence rates varied widely from 6 to 61.7 %. Numerous studies reported that clinical outcomes for patients with PJK were not significantly different from those without, except in one recent study in which adult patients with PJK experienced more pain. Risk factors for PJK included age at operation, low bone mineral density, shorter fusion constructs, upper instrumented vertebrae below L2, and inadequate restoration of global sagittal balance. Prevalence of PJK following long spinal fusion for adult spinal deformity was high but not clinically significant. Careful and detailed preoperative planning and surgical execution may reduce PJK in adult spinal deformity patients.