1 INTRODUCTION Discectomiesinlumbosacral disc herniation was first described byMixter and Barr in 1934 as a combination of laminotomy,disc removal, and neural decompression.AfterLove (1939) andCasper (1977), spinal surgery was considered minimally invasive whena new procedure which reduced tissue injury to the minimum was discovered. In 1997, Foley proposed a new method usingdilators with increasing diameters to approach via paraspinal muscles with support of endoscope and special systems. This method made the posterior approach in discectomies genuinely ‘minimally invasive’. In Vietnam, spinal surgery, especially minimally invasive spinal surgery, has only been paid attention to develop in recent years. According to VISTA network from the National Agency for Science and Technology Information, to the end of 2012, there have been 137 articles about spinal issues; among these, 40 articles are about spinal surgery and one is related to minimally invasive surgery using dilators. Of 493,413 PhD theses in the National Library, 29 theses are related to treatment of spinal conditions; however, there are no theses mentioning minimally invasive surgery using dilators. This is a new approach in Vietnam, and the data about its safety and efficiency are limited. Hence, we conduct a study on “Application of tubular retractordiscectomy for single-level lumbosacral disc herniation in Viet Duc University Hospital” with two aims: 2 1. To describe the clinical and paraclinical characteristics of single-level lumbosacral disc herniation,and 2. To evaluate the surgical outcome, indication and surgical protocol of the surgery of lumbosacral disc herniation using dilators. Contribution: - A study with adequacy of diagnostic criteria and indication for surgery using dilators. - Formulate the diagnostic approach and treatment indication of single-level lumbosacral disc herniation. Content: 128 pages in 4 chapters: Introduction 3 pages Chapter 1: Overview 33 pages Chapter 2: Method 25 pages Chapter 3: Results 26 pages Chapter 4: Discussion 39 pages Conclusion 2 pages 3 The thesis includes 25tables, 10charts, 55figures, 141references (18in Vietnamese, 122in English, 1 in German). 4 Chapter 1 OVERVIEW 1.1. HISTORY OF MINIMALLY INVASIVE DISCECTOMIES 1.1.1. International In 1975, Hijikata described the first case of percutaneous discectomy. Recent studies focused on laser and radiofrequency (RF) in minimally invasive treatment of disc conditions. Minimally invasive spinal surgery, especially minimally invasive discectomy,has been evolving rapidly in recent years. Minimally invasive discectomies using the Minimal Exposure Tubular Retractor (METRx) system was developed in 1994 and was first applied in 1997 by Medtronic Sofamor Danek Inc. (USA). In 2003, the company was awarded the patent for the minimally invasive intervertebral fixation and proposed the TLIF surgery using the METRx system. To 2004, there have been over 6000 patients treated with the METRx system in about 500 surgical centers. METRx is a method using the dilators with increasing length and diameters to approach via the paraspinal muscles. Its strength is to preserve muscular and tendon structures at midline. The METRx with Quadrant system have more strengths: adequate space, sufficient lighting, and applicable for migrated 5 herniation. Other applications are minimally invasive laminotomy, minimally invasive foraminotomy, bilateral spinal canal opening by minimally invasive unilateral approach 1.1.2. In Vietnam Lumbosacral discectomies have been implemented in recent years. Of the minimally invasive operations, some approaches have been applied in clinical practice, such as percutaneous disc decompression with laser or RF, or lumbosacral endscopic discectomy. Son DN et al performed lumbosacral endscopic discectomy in 70 patients. Thach NV et al applied RF in treatment of cervical and lumbosacral disc herniation. Duyet TC et al performed percutaneous disc decompression with laser in 10 years (1999-2009) in 3,173 patients (age 14-91) with total intervened discs of 5,909 It can been seen that surgical centers specialized in spinal surgery have been implementing minimally invasive techniques, but studies on surgery using dilators are limited. 1.2. ANATOMY RELATED TO MINIMALLY INVASIVE SURGERY From the inferior border of the pedicle, the vertebrae can be divided into six components – three superior components including 2 superior articular processes, 2 transverse processes, and 2 pedicles; and three inferior components including 2 laminae, 2 inferior articular processes, and 1 spinal process. The only components that lie at the same level of the inferior border are the junctions between the lamina and the pedicle. 6 From inferior to superior, there are three floors as described: floor 1 (disc), floor 2 (intervertebral foramen), and floor 3 (pedicle). Depending on the position of the migrated disc, we will direct the dilators to the area under the support of C-arm. Some anatomic abnormalities of the lumbosacral spine are congenital bone deformities and lumbosacral root abnormalities. 1.3.CLINICAL AND PARACLINICAL CHARACTERISTICS OF LUMBOSACRAL DISC HERNIATION: 1.3.1. Clinical signs and symptoms: Two major syndromes: Lumbar syndrome (low back pain, paraspinal localized pain, limited range of motion of the lumbar spine) and Nerve-root syndrome (pain radiating to the area supplied by the nerve,root stimulating signs, Lasègue sign, sensory disorder, motor disorder, deep tendon reflex disorder). 1.3.2. Imaging: Plain spine X-raycan evaluate spine instability and the condition of the posterior arch.Lumbosacral CT scancan provide better assessment of the bony structure and detect some abnormalities.Lumbosacral MRIcan detect different types of disc herniation:disc protrusion (protrusion of the nucleus pulposus outside of the 7 border of the adjacent vertebrae); disc extrusion (extrusion of the nucleus pulposus outside of the fibrous ring); anddisc migration (the nucleus pulposus is sequestrated and separated from the disc). 1.4.SURGICAL TREATMENT OF LUMBOSACRAL DISC HERNIATION 1.4.1. Open discectomy Oppenheim and Krause (1909) andWilliam J.Mixterand Joseph Barr (1934) proposed open laminectomy, exposureand transdural discectomy.Love (1939) performed posterior discectomy without laminectomy. 1.4.2.Minimally invasive discectomy with METRx and Quadrant In 2003, the METRx system (Medtronic Inc.) was introduced. Together with video andmicrosurgical microscope,the system has spread the technique widely all over the world. The lateral approach is direct to the location of the decompression. The increasing-in-diameter dilators put inside one another help dilate the paraspinal muscles, and the last dilator is connected to the flexible arm fixed to the operating table. The last dilator can be an 18-mm or 22-mm rounded tube, a 4-piece X-tube, or QUADRANT – made from two semicircular pieces that can be dilated along the spine and are connected to the cold lighting source by the optical fiber cable. 8 Chapter 2 METHOD 2.1. SUBJECTS: 151 patients, treated withminimally invasive discectomy using METRx and Quadrant in the Department of Spinal Surgery –Viet Duc University Hospital, fromOctober 2008 toOctober 2011. 2.2. METHOD: Study design: cross-sectional. Sample size:convenient sampling, including all the eligible patients during the study time. 2.3. PLANNING: 2.3.1. Data collection: Using a pre-designed study medical report. 2.3.2. Information collected before study: Preoperative information: + General informatino: age; gender; occupation; past history. + Clinical characteristic: 9 *Lumbar syndrome: the Numerical Rating Scale to assess low back pain and leg pain;the Owestry Disability Index. * Nerve-root compression syndrome:sensory disorder, Lasègue sign, deep tendon reflex disorder. * Muscle strength and sensory assessment: ASIA (2006). + Imaging: Plain X-ray andbendingX-ray,lumbosacral MRI. Treatment indication: + Surgical indication: disc hernation with cauda equina syndrome(emergency); disc herniation with paralysis (due to compression). + Surgical indication with dilators:criteria are (1) single-levelherination; (2) herniation without instability; (3) herniation without spinal stenosis; và (4) herniation with pain radiation to unilateral leg, consistent wih the side of compression. + Exclusive criteria:Absolute contraindication- (1) Lumbar spine instability; (2) Spinal stenosis, multiple-level disc herniation (≥3 level); and (3) Systemic diseases that are contraindicated to surgery. Relative contraindication–previous surgery at the side of compression (recurrent herniation); coagulopathy; >2-level herniation; and surgical center out of capabilities. 10 Minimally invasive discectomy with METRx and Quadrant: Technical requirements:IntraoperativeC–arms (SIEMENS Pb r8 N40 fo90), METRx and Quadrant system (Medtronic Inc), specialized surgical instruments. Discectomy with dilators. Early rehabilitation (48 hour postoperative). Wear lumbosacral back brace in 2 weeks. Postoperative information: Using the study medical report, after 6 and 12 months. • Clinical:NRS, ODI, general outcome • Imaging:MRI, bending X-ray. • Time to back-to-work • Ouctcome assessment based onmodified Macnab criteria. 2.4.DIAGNOSTIC AND TREATMENT APPROACH OF LUMBOSACRAL DISC HERNIATION 2.4.1. Preoperative assessment Clinical: History taking and physical examination. Imaging:Lumbosacral X-ray and MRI. Surgery indicated when: (1) Herniation with cauda equina syndrome (emergency); (2) Disc herniation [...]... after 6 months andto 1,4 after 12 months (both with p . anatomic abnormalities of the lumbosacral spine are congenital bone deformities and lumbosacral root abnormalities. 1.3.CLINICAL AND PARACLINICAL CHARACTERISTICS OF LUMBOSACRAL DISC HERNIATION: 1.3.1 laser or RF, or lumbosacral endscopic discectomy. Son DN et al performed lumbosacral endscopic discectomy in 70 patients. Thach NV et al applied RF in treatment of cervical and lumbosacral disc herniation instability and the condition of the posterior arch.Lumbosacral CT scancan provide better assessment of the bony structure and detect some abnormalities.Lumbosacral MRIcan detect different types of disc