Incidence and clinical significance of vascular encroachment resulting from freehand placement of pedicle screws in the thoracic and lumbar spine: analysis of 6816 consecutive screws.
METHODS
Retrospective case series.


OBJECTIVE
Evaluate the incidence and clinical significance of vascular encroachment resulting from freehand placement of pedicle screws in the thoracic and lumbosacral spine.


BACKGROUND
Pedicle screws are routinely used to effectively stabilize all 3 columns of the spine but can be technically demanding to place in the setting of variable anatomy. There is a paucity of data regarding iatrogenic major vascular injuries during posterior instrumentation procedures.


METHODS
We retrospectively reviewed the records of all patients undergoing freehand pedicle screw placement without image guidance in the thoracic or lumbar spine during a 7-year period. The incidence and extent of vascular encroachment by a pedicle screw was determined by review of routine postoperative computed tomographic scans obtained within 24 hours of all surgical procedures. Vascular encroachment was defined as a pedicle screw that was touching or deforming the wall of a major vessel.


RESULTS
A total of 964 patients received 6816 freehand-placed pedicle screws in the thoracolumbar spine. Fifteen (0.22%) screws that encroached a major vascular structure were identified. Ten (0.29%) thoracic pedicle screws encroached on the aorta, 4 (0.14%) lumbar screws on the common iliac vein, and 1 S1 screw (0.19%) on the internal iliac vein. In consultation with vascular surgery, it was determined whether revision surgery and the technique/approach for the revision procedure should be recommended. Two (0.21%) patients required revision surgery to remove the encroaching pedicle screw (T5 and T8) due to concern for vascular injury. Both patients were asymptomatic and recovered without further complications after revision surgery.


CONCLUSIONS
Vascular encroachment of major vessels occurs rarely in the setting of freehand pedicle screw placement in the thoracolumbar spine. Although rare, delayed vascular injury from errant pedicle screw placement has been reported in the literature. The aorta seems to be the vessel at the highest risk of injury. Routine intraoperative or postoperative computed tomographic scanning allows for early identification of pedicle screws encroaching on vascular structures thereby facilitating early revision surgery.


METHODS
4.
*Department of Neurosurgery, Vanderbilt University Medical Center, Nashville, TN; and †Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, MD.
Scott L
SL
Parker
Anubhav G
AG
Amin
David
D
Santiago-Dieppa
Jason A
JA
Liauw
Ali
A
Bydon
Daniel M
DM
Sciubba
Jean-Paul
JP
Wolinsky
Ziya L
ZL
Gokaslan
Timothy F
TF
Witham
D000328:Adult; D000368:Aged; D015142:Baltimore / Q000453:epidemiology; D001863:Bone Screws; D005260:Female; D006801:Humans; D015994:Incidence; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D012086:Reoperation; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000009:adverse effects* / Q000295:instrumentation*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D057772:Vascular System Injuries / Q000175:diagnosis / Q000453:epidemiology* / Q000601:surgery