RESUMO
Correct alignment of pedicle screws is imperative in multilevel instrumentation. However, there has been no report addressing the technical aspects of this subject. If the head diameter of a pedicle screw is D, the head height is H, and the convergence angle of the screw being inserted is alpha, then the distance between the extension line of the medial borders of the inserted screw heads and the insertion point of the adjacent screw (A) is described by the following formula: A = 1/2Dcos alpha- Hsin alpha If an L3 pedicle screw (D=13 mm, H=15 mm) is to be inserted with a convergence angle of 14 degrees after the insertion of L4 and L5 screws, its insertion point should be 3.6 mm medial to the extension line of the centers of the L4 and L5 screws and 2.7 mm lateral to the extension line of their medial borders for all screw heads, so it can be aligned in the coronal plane. In order to achieve the best alignment, a pedicle screw is inserted between the extended line of the centers and that of the medial borders of the inserted adjacent screw heads. For the routine range of convergence angles, it is essential to move the entry point medially toward the extended line connecting the medial borders of the inserted adjacent screw heads.
Assuntos
CabeçaRESUMO
Traumatic tetraplegia is an overwhelming injury often requiring permanent adaptations by patients and families. The greatest potential for improving the quality of life lies with rehabilitation and restoration of upper extremity function. Functional surgery of upper limb following tetraplegia is individualized based on functional level and can significantly improve hand functional quality of life. We haveobserved a 46-year old man with a C5 complete spinal cord injury and the patient had achieved functional improvement of upper extremity by functional surgery of upper limb for tendon transfer of posterior deltoid to triceps muscle and biceps tendon release.