title: Time to development, clinical and radiographic characteristics, and management of proximal junctional kyphosis following adult thoracolumbar instrumented fusion for spinal deformity.
abstract: METHODS
  A 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).
  
  
  BACKGROUND
  PJK continues to be a common mode of failure following ASD surgery. Although literature exists on possible risk factors, data on management remain limited.
  
  
  METHODS
  A retrospective review of medical records of 289 consecutive ASD patients who underwent posterior segmental instrumentation incorporating at least 5 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 (range, 1.3-61.9±19 mo). Sixteen (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 preindex and postindex surgery radiographic parameters demonstrated significant improvement in mean lumbar lordosis (24 vs. 42 degrees, P<0.001), pelvic incidence-lumbar lordosis mismatch (30 vs. 11 degrees, P<0.001), and pelvic tilt (29 vs. 23 degrees, P<0.011). The mean T5-T12 kyphosis worsened (30 vs. 53 degrees, P<0.001) and the mean global sagittal spinal alignment failed to improve (9.6 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 preoperative 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.
authors: *Department of Neurosurgery, University of Virginia Medical Center, Charlottesville, VA †Department of Neurosurgery, Oregon Health and Sciences University, Portland, OR ‡Department of Orthopedic Surgery, University of Pennsylvania, Philadelphia, PA.
authors: Davis L
authors: DL
authors: Reames
authors: Manish K
authors: MK
authors: Kasliwal
authors: Justin S
authors: JS
authors: Smith
authors: D Kojo
authors: DK
authors: Hamilton
authors: Vincent
authors: V
authors: Arlet
authors: Christopher I
authors: CI
authors: Shaffrey
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001863:Bone Screws; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D008141:Lordosis / Q000601:surgery; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D010384:Pelvic Bones / Q000000981:diagnostic imaging / Q000473:pathology; D011859:Radiography; D012086:Reoperation / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012307:Risk Factors; D013123:Spinal Fusion / Q000009:adverse effects / Q000379:methods*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D017211:Treatment Failure; D016896:Treatment Outcome