Dalley, 10th Edition

111

Vertebral Column

2

FIGURE B2.14. Disc degeneration treated by disc replacement and spinal fusion. A. Degeneration of L1–L2 IV disc ( arrow ) compromising IV foramen, L1 nerve; pain radiating to inguinal region. B. Disc space restored with bridge ( arrow ) indicated by vertical radiopaque markers. C. Fusion of L1 and L2 vertebrae by replacement of bridge with new bone. (A) Lateral radiograph (B) Lateral radiograph (C) Lateral radiograph 1 day prior to surgery 1 month postoperation 5 years postoperation

Fractures and Dislocations of Vertebrae

The graft will eventually be replaced by new bone that unites the adjacent vertebral bodies (Fig. B2.14C). Usually metal im plants (“rods”) are placed to hold the vertebrae in place while the new bone grows. This surgery is more effective in relieving numbness, pain, or weakness in the lower limbs than in reliev ing back pain per se. The compromised range of motion may increase stress on adjacent segments, especially when multiple segments are fused, eventually inducing more pathology. Arti cial disc replacement has been developed as an al ternative to fusion when one or two segments are involved. A prosthetic disc restores disc space lost to marked disc de generation, relieving stenosis, while still allowing motion to occur. Another possible bene t is the prevention of prema ture breakdown of adjacent segments. The zygapophysial joints are of clinical interest be cause they are close to the IV foramina through which the spinal nerves emerge from the vertebral canal. When these joints are injured or develop osteophytes ( osteoarthritis ), the spinal nerves are often affected (see Fig. B2.9A). This causes pain along the distribution patterns of the dermatomes and spasm in the muscles derived from the associated myotomes . A myotome consists of all muscles or parts of muscles receiving innervation from one spinal nerve. Denervation of lumbar zygapophysial joints is a proce dure used for treatment of back pain caused by disease of these joints. The nerves are sectioned near the joints or are destroyed by radiofrequency percutaneous rhizolysis (G. rhiza , root + G. lysis , dissolution) or neurotomy ( Fig. B2.15). The denervation is directed at the articular branches of two adjacent posterior rami of the spinal nerves because each joint receives innervation from both the nerve exiting at that level and the superjacent nerve (see Fig. 2.21). Injury and Disease of Zygapophysial Joints

Although the construction of the vertebral column permits a considerable amount of movement as well as support and protection, excessive or sudden violent movement or movement of a type not per mitted in a speci c region is likely to result in fractures, dis locations, and fracture–dislocations of the vertebral column. Sudden forceful exion, as occurs in automobile accidents or from a violent blow to the back of the head, commonly produces a crush or compression fracture of the body of one or more vertebrae. If violent anterior movement of the ver tebra occurs in combination with compression, a vertebra may be displaced anteriorly on the vertebra inferior to it (e.g., dislocation of C6 or C7 vertebrae) (see the Clinical Box “Dislocation of Cervical Vertebrae” in this chapter). Usually

FJ

RF cannula

P

L3

SP

TVP Copyright © 2027 Wolters Kluwer. Unauthorized reproduction of the article is prohibited.

SAP

P

SP

L4

FIGURE B2.15. Radiofrequency neurotomy of medial branch nerves L3, L4. FJ , facet joint; P , pedicle; RF , radiofrequency; SAP , superior articular process; SP , spinous process; TVP , transverse process.