Stabilization of 2-column thoracolumbar fractures with orthoses: a cadaver model.

STUDY DESIGN

A gross anatomic and motion analysis study in cadavers.

OBJECTIVE

Assess spinal motion in a cadaveric spinal fracture model and investigate the ability of external orthoses to control this motion.

SUMMARY OF BACKGROUND DATA

External orthoses are frequently prescribed for patients who have experienced burst fracture of the thoracolumbar spine. Despite the substantial expense involved, there is little data confirming their value.

METHODS

A T12 burst fracture model was created in 5 lightly embalmed cadavers by resecting the anterior and middle columns of the T12 vertebra through a thoracolumbar anterior approach to the spine. An electromagnetic motion tracking and analysis system was used to track angular and linear displacement at the fracture during routine patient maneuvers. Several commonly used orthoses, including an extension brace and both an "off-the-shelf" and custom-molded thoracic-lumbar-sacral orthosis (TLSO), were applied to the cadavers and the affect on fracture site motion was assessed.

RESULTS

Application of all 3 styles of brace resulted in angular motion of 8° to 12° in flexion-extension, 11° to 20° in axial rotation, and 8° to 10° of lateral bending. Brace application resulted in linear displacement of 29 to 46 mm in the medial-lateral plane, 21 to 23 mm in the axial plane, and 21 to 37 mm in the anterior-posterior plane. During logrolling maneuvers, TLSO style braces diminished angular motion, although residual motion in the range of 5° remained. TLSO style braces had little effect on linear translation. When placed in a seated position in bed, TLSO style braces diminished flexion and extension modestly, but did not influence lateral bending or linear translation. Extension style braces had no effect on fracture motion during any activity tested.

CONCLUSION

In a cadaver model of a burst fracture, there is surprising angular and linear motion at the fracture during common hospital activities. TLSO orthoses can decrease angular motion but do not effect translation at the fracture. An extension orthosis had no effect on motion at the spinal fracture site.