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Decompression Surgery. Laminectomy and Facetectomy. Discectomy. Nucleotomy. Effect of Spinal Decompression on Spinal Stability. Surgical Decompression:
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Effect of Spinal Decompression on Spinal Stability • Surgical Decompression: • Removal of spinal elements that impinge the spinal cord or nerve root due to spinal disorders, such as tumor, trauma, infection, or degenerative changes • Goals of Decompression: • To relieve pain; • To prevent neurologic problems • Controversies associated with decompression: • How much decompression can induce hypermobility? • When to fuse and when not to fuse? These initiated the controlled biomechanical studies on the effect of decompression on the spinal motion.
Effect of Discectomy in the Lumbar Spine • No FLX/EXT changes in patients with discectomy and minimal laminectomy • Tibrew et al. • Evidence of hypermobility in patients (particularly female patients) after excision of L4-5 disc • Frymoyer & Selby • Biomechanical study showed that partial discectomy increases FLX, LB and AR motions significatly (Goel et al.) • Flexibility test using cadavers (6.9 Nm maximum moment) • Tested Cases: • Intact • Disc herniation (or protrusion): simulated by cutting the posterolateral part of the AF horizontally • Partial discectomy: simulated by removing small amount of NP in addition to partial AF removal
Effect of Laminectomy & Facetectomy in the Lumbar Spine • Abumi et al.: Effect of graded facetectomy • FLX increases with uni- and bilateral medial facetectomy with division of supra- and inter-transverse ligaments. • Total facetectomy (uni- or bi-lateral) created significant motion increase in FLX and AR • Goel et al.: • FLX, AR and LB motion increased in the presence of uni-lateral partial facetectomy & facetectomy. • Additional removal of total NP increases rotational motions in all directions compared to the intact case. • Bilateral laminectomy and facetectomy also increases the FLX and AR motions • Clinical evidence is not as evident as biomechanical studies.
Effect of Decompression in the Thoracic Spine • The vertebral body is completely removed (vertebrectomy) in most cases. • Vertebrectomy makes the spine unstable, and the fusion and instrumentation is recommended.
Decompression of the Cervical Spine • Anterior approach: Discectomy or Corpectomy • Reconstruction with an interbody graft • In case of single level surgery, the interbody grafting is sufficient for maintaining segmental stability if the posterior elements are intact. • Posterior Approach: Laminectomy and Foraminotomy • Common complications of laminectomy: Development of kyphosis, instability and inadequate decompression • In adults, laminectomy is not frequent, and it does not produce significant motion increase (biomechanical study).
Effect of Partial or Total Facetectomy(Biomechanical Studies of the Cervical Spine) • Panjabi et al.: • FLX increases with disruption of all posterior structures. • EXT increases with disruption of all anterior ligaments. • Horizontal motion increases after removal of facet joint. • Zdeblic et al.: • FLX and AR increase after 75% or 100% facetectomy. • No significant motion changes after laminectomy alone or after resection of 25% or 50% of the facet. • FLX and AR increase after more than 50% facet capsule resection after laminectomy.