Proximal Junctional Kyphosis in Primary Adult Deformity Surgery: Evaluation of 20 Degrees as a Critical Angle.

1Regions Hospital, Neurosurgery Department, Saint Paul, MN 2Washington University Medical Center, Department of Orthopaedic Surgery, St. Louis, MO 3Department of Orthopaedics, Mount Sinai School of Medicine, New York, NY 4Dept. of Orthopedic Surgery, Albert Einstein Medical Center, Philadelphia, PA 5University of Minnesota, Department of Orthopaedic Surgery, Minneapolis, MN.
Neurosurgery (Impact Factor: 3.03). 02/2013; DOI: 10.1227/NEU.0b013e31828bacd8
Source: PubMed

ABSTRACT BACKGROUND:: Multiple studies have reported on the prevalence of proximal junctional kyphosis (PJK) following spinal deformity surgery; however, none have demonstrated its significance with respect to functional outcome scores or revision surgery. OBJECTIVE:: To evaluate if 20° is a possible critical PJK angle in primary adult scoliosis surgery patients as a threshold for worse patient-reported outcomes. METHODS:: Clinical and radiographic data of 90 consecutive primary surgical patients at a single institution (2002-2007) with adult idiopathic/degenerative scoliosis and 2 yr minimum follow-up were analyzed. Assessment included radiographic measurements, but most notably sagittal Cobb angle of the PJ angle at pre-op, between 1-2 months, 2 yrs, and ultimate follow-up. RESULTS:: Prevalence of PJK ≥ 20° at 3.5 years was 27.8% (N=25). Those with PJK ≥ 20° at ultimate follow-up were older (mean 56 vs. 46yrs.), had lower number of levels fused (median 8 vs. 11), and were proximally fused to the lower thoracic spine more often than upper thoracic spine (all P <.001). PJK ≥ 20° was associated with significantly higher BMI and fusion to the sacrum with iliac screws (P<0.016, P<0.029 respectively). Scoliosis Research Society (SRS) outcome score changes were lower for PJK patients, but not significantly different from those in the non-PJK group. CONCLUSION:: PJK ≥ 20° in primary adult idiopathic/degenerative scoliosis does not lead to revision surgery for PJK, but is univariately associated with older age, shorter constructs starting in the lower thoracic spine, obesity, and fusion to the sacrum. The negative results, supported by SRS outcome data, provide important guidance on the post-operative management of such PJK patients.

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