Spine
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The purpose of this study was to examine the mechanical function of the C1-C2 capsular ligaments. Physiologic torques of up to 1.5 Nm were applied to human fresh cadaveric specimens (C0-C1-C2-C3) in three dimensions, and the three-dimensional motion of C1 relative to C2 was recorded. Two groups of cadaveric specimens were used to study the effect of two different sequential ligamentous transections. ⋯ Lateral bending to the left also increased significantly by 1.5 degrees after both ligaments were cut. In the second group, with the nonfunctional alar and transverse ligaments, transection of the left capsular ligament resulted in greater increases in range of motion: 3.3 degrees to the right and 1.3 degrees to the left. Lateral bending to the right also increased significantly by 4.2 degrees.
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Spinal cord plasticity in 55 patients with cervical compression myelopathy was assessed with magnetic resonance imaging, by which the transverse area of the spinal cord was measured at the site of maximum compression before and after surgery and compared with the conventional modalities of computed tomographic myelography. A high correlation (r = 0.901, P less than 0.01) was observed between the preoperative measurements of magnetic resonance imaging and computed tomographic myelography. The preoperative transverse area was in good correlation with the preoperative Japanese Orthopaedic Association score (r = 0.466, P less than 0.01). In most patients with a spinal cord area of less than 0.45 cm2, the clinical results were poor despite considerable morphologic restoration of the spinal canal obtained after decompression surgery, reflecting an irreversible pathology developed in the spinal cord.