477 - Incidence, Risk Factors and Characteristics of Proximal Segment Fractu...

#477 Incidence, Risk Factors and Characteristics of Proximal Segment Fractures in Posterior Spinal Fusion

Oral Posters: Deformity

Presented by: J. Schreiber

Author(s):

F. Taher (1)
D.S. Meredith (2)
D.R. Lebl (3)
J.J. Schreiber (2)
F.P. Cammisa (3)
F.P. Girardi (3)

(1) Hanusch-Krankenhaus, Vienna, Austria
(2) Hospital for Special Surgery, New York, NY, USA
(3) Hospital for Special Surgery, Spine Service, New York, NY, USA

Abstract

Introduction: Proximal segment fractures following spinal fusions are considered relatively uncommon, but recent demographic development resulting in an aging spine surgical patient population, with a higher potential for decreased bone health, may lead to an increase in this complication. An understanding of surgical and patient factors contributing to proximal fractures is important to avoid and manage them.

Methods: The physical surgical log of a single spine surgeon was reviewed for cases of four or more level posterior fusions extending to the sacrum or pelvis. The electronic medical records and radiographic images of these patients were reviewed for the occurrence of fractures proximal to the fusion construct. The incidence of proximal segment fractures within the cohort is reported and assessed individually for constructs which had their upper instrumented vertebra high-thoracic (T1-T5), mid-thoracic (T6-T10) and thoraco-lumbar (T11-L2). Demographic data, patient characteristics and bone health, as characterized by Hounsfield unit measurements from computed tomography studies obtained prior to the index procedure, are reported for the fracture cases.

Results: One hundred and ninety-seven posterior fusion cases extending from L2 or higher to the sacrum or pelvis were identified from the 2002-2010 operative logs of one spine surgeon. Twenty-six of these 197 cases developed a fracture proximal to their spinal fusion constructs (13.1%). The mean time from index surgery to symptomatology related to the fracture was 7.5±13.2 months. The most abundant presenting symptom was back pain (24/26 patients, 92.3%) and a majority of the fractures was diagnosed on plain radiographs (88.5%). Twenty-one of the 26 cases (80.8%) had to undergo surgical treatment for their complication. There was a significantly higher incidence of fractures in fusion constructs ending mid-thoracic than in those ending thoracolumbar (p< 0.01). Bone mineral density, as characterized by Hounsfield unit measurements on CT, was reduced in the study cohort, as compared to historical data on controls with normal Dual-Energy X-ray Absorptiometry results, as well as when compared to age, gender and procedure matched controls without a postoperative adjacent segment fracture (p< 0.01).

Conclusion: Proximal segment fractures deserve consideration as a complication of long posterior constructs extending to the sacrum or pelvis. In this cohort, patients with a fusion construct ending mid-thoracic were more likely to suffer from a proximal segment fracture than those with fusions ended thoraco-lumbar. This fits in with previous reports suggesting an endpoint at the apex of the kyphosis to be a more important risk factor for proximal junction kyphosis and proximal fractures than an endpoint in proximity to relatively mobile motion segments in the lower lumbar spine and thoraco-lumbar junction. Reduced bone mineral density within the cohort of fracture cases underlines the importance of bone health as a determinant of complication rates following spinal fusion surgery.