Facet-sparing lumbar decompression with a minimally invasive flexible MicroBlade Shaver® versus traditional decompression: quantitative radiographic assessment.

By London Spine
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Facet-sparing lumbar decompression with a minimally invasive flexible MicroBlade Shaver® versus traditional decompression: quantitative radiographic assessment.

Clin Interv Aging. 2012;7:257-66

Authors: Lauryssen C, Berven S, Mimran R, Summa C, Sheinberg M, Miller LE, Block JE

Abstract
BACKGROUND: Laminectomy/laminotomy and foraminotomy are well established surgical techniques for treatment of symptomatic lumbar spinal stenosis. However, these procedures have significant limitations, including limited access to lateral and foraminal compression and postoperative instability. The purpose of this cadaver study was to compare bone, ligament, and soft tissue morphology following lumbar decompression using a minimally invasive MicroBlade Shaver® instrument versus hemilaminotomy with foraminotomy (HL).
METHODS: The iO-Flex® system utilizes a flexible over-the-wire MicroBlade Shaver instrument designed for facet-sparing, minimally invasive “inside-out” decompression of the lumbar spine. Unilateral decompression was performed at 36 levels in nine human cadaver specimens, six with age-appropriate degenerative changes and three with radiographically confirmed multilevel stenosis. The iO-Flex system was utilized on alternating sides from L2/3 to L5/S1, and HL was performed on the opposite side at each level by the same investigator. Spinal canal, facet joint, lateral recess, and foraminal morphology were assessed using computed tomography.
RESULTS: Similar increases in soft tissue canal area and decreases in ligamentum flavum area were noted in nondiseased specimens, although HL required removal of 83% more laminar area (P < 0.01) and 95% more bone resection, including the pars interarticularis and facet joints (P < 0.001), compared with the iO-Flex system. Similar increases in lateral recess diameter were noted in nondiseased specimens using each procedure. In stenotic specimens, the increase in lateral recess diameter was significantly (P = 0.02) greater following use of the iO-Flex system (43%) versus HL (7%). The iO-Flex system resulted in greater facet joint preservation in nondiseased and stenotic specimens. In stenotic specimens, the iO-Flex system resulted in a significantly greater increase in foraminal width compared with HL (24% versus 4%, P = 0.01), with facet joint preservation.
CONCLUSION: The iO-Flex system resulted in significantly better decompression of the lateral recess and foraminal areas compared with HL, while preserving posterior spinal elements, including the facet joint.

PMID: 22879740 [PubMed – indexed for MEDLINE]

Sparing the posterior surgical site when planning radiation therapy for thoracic metastatic spinal disease.

By London Spine
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Sparing the posterior surgical site when planning radiation therapy for thoracic metastatic spinal disease.

Spine J. 2012 Apr;12(4):324-8

Authors: Verlaan JJ, Westhoff PG, Hes J, van der Linden YM, Castelein RM, Oner FC, van Vulpen M

Abstract
BACKGROUND CONTEXT: Most patients with painful spinal metastases are sufficiently palliated by hypofractionated radiotherapy. However, a small group of patients will need surgical intervention to treat symptomatic spinal cord compression and/or gross mechanical instability. Irradiation of a (prospective) surgical area may lead to postsurgery complications, including wound dehiscence, infection, and chronic wound ulcers. Decreasing the radiation dose to the surgical area could reduce radiation-induced toxicity and associated surgical complications.
PURPOSE: To investigate an alternative radiation technique designed to lower the surgical area dose while delivering an adequate target dose and minimal off-target dose.
STUDY DESIGN: Comparison of radiation doses received by various anatomic structures after simulating irradiation with a routine posteroanterior single field (SF) technique and experimental multiple field (MF) technique in a setting of thoracic metastatic spinal disease.
METHODS: The computed tomography (CT) data from six previously treated patients with a total of 10 thoracic spinal metastases were used to plan four radiation schemes (SF8 Gy; SF20 Gy; MF8 Gy; and MF20 Gy). Discrete anatomic structures were defined on CT data, including a posterior surgical area, and after simulation the doses received were calculated and compared for the 8 Gy and 20 Gy techniques.
RESULTS: With the experimental MF technique, a clinically relevant dose could be delivered to the affected vertebra, whereas the dose received at the (prospective) surgical area could be significantly reduced compared with the SF technique. The dose received at the nontarget tissues fell below the threshold level for clinical relevance.
CONCLUSIONS: This radiation planning study showed the feasibility of sparing the surgical area while delivering an adequate dose to affected vertebrae in thoracic metastatic spinal disease.

PMID: 22436488 [PubMed – indexed for MEDLINE]