Minimally Invasive Spine Surgery: Lumbar Case Studies

44 Minimally Invasive Spine Surgery: Lumbar Case Studies


Mick J. Perez-Cruet, Richard G. Fessler, Roman Chornij, and Michael Y. Wang


Abstract


Minimally invasive surgery has made its greatest advances in the treatment of lumbar pathology due to the prevalence of pathology in the lumbar spine. Mastering these techniques will expand the surgeon’s armamentarium to treat a variety of lumbar spinal disorders. This chapter illustrates the use of a number of techniques and technologies developed to treat a variety of lumbar conditions. Seven unique cases are presented in the chapter. These techniques and technologies offer patients improved outcomes while reducing approach-related morbidity.


Keywords: lumbar spine, case studies, minimally invasive spinal surgery, lumbar microendoscopic discectomy, incidental durotomy, transforaminal lumbar interbody fusion, percutaneous screws, decompression, pseudarthrosis, pedicle subtraction osteotomy, spinal realignment, spinal misalignment, fusion/fixation, lateral lumbar interbody fusion, minimally invasive decompression, progressive spondylolisthesis, lumbar stenosis, degenerative dextroscoliosis


44.1 The Evolution of Lumbar Minimally Invasive Spine Surgery


Nowhere has minimally invasive spinal surgery (MIS) gained greater adoption than in the lumbar spine. The prevalence of thoracolumbar pathology, the need for better methods of treatment, and the proliferation of technologies have all synergized to allow for rapid advancements in this area of the spinal column over the past decade. Anterior mini-open retroperitoneal, lateral transpsoas, and trans-sacral approaches have been developed. Decompression via tubular, endoscopic, and indirect methods has been innovated to replace a standard open laminectomy. Percutaneous screws, transfacet screws, facet interference constructs, and cortical trajectories have all allowed for less invasive fixation.


Today, MIS methods are available for treating a wide spectrum of lumbar spinal pathologies. In addition to degenerative disease, neoplasms, infection, trauma, and deformity are now all accessible through less invasive approaches. Given the continuing advances in osteobiologics, material science, optics, robotics, and miniaturization, innovation in this area will likely continue to evolve the fastest.


44.2 Case 1: Lumbar Microendoscopic Discectomy


44.2.1 Patient Profile


A 38-year-old man with a 2-month history of low back and left lower extremity pain extending from the sacrum to the lateral calf. He can only walk if he leans to the left. Leaning to the right causes severe pain in right lateral calf. The patient is in extreme pain.


44.2.2 Case Selection


The patient showed a central disc herniation at L4–L5 (image Fig. 44.1).


44.2.3 Preoperative Notes


The patient failed 6 weeks of nonoperative therapy including physical therapy (PT) and chiropractic manipulation. He was offered epidural steroid injection (ESI), but he refused.


44.2.4 Instrumentation Notes


There is no indication for instrumentation is this case.


44.2.5 Surgical Approach and Technique


The patient was induced with general anesthesia and intubated endotracheally. Appropriate arterial and venous access was obtained. The patient was then turned into the prone position on the Wilson frame. Fluoroscopy was placed in the lateral position and the patient’s lumbar spine was shaved, prepped, and draped in the usual sterile fashion. Using lateral fluoroscopy, an appropriate incision to approach the left L4/L5 level was identified and marked 1.5 cm off the midline. This area was infiltrated with 0.5% Marcaine with epinephrine. A no. 10 scalpel was then used to incise the skin over approximately 2 cm. Hemostasis was obtained with bipolar cautery. A Kirschner wire (K-wire) was then placed through the incision and advanced to the L4/L5 facet. This position was confirmed fluoroscopically. A series of dilators was then placed over the K-wire, and after the first dilator was placed the K-wire was removed. Finally, the working channel was positioned, angled medially, and locked in place. This position was confirmed fluoroscopically. Camera was then introduced into the working channel. Bovie cautery was used to remove a small amount of residual tissue at the bottom of the working channel. An angled curette was then used to define the sublaminar space. Kerrison punch was used to perform a hemilaminotomy and this was extended into a medial facetectomy using the Legend (Sofamor Danek, Memphis, TN) drill with a cutting M8 burr. The traversing nerve root was then retracted slightly medially, and the epidural space explored. The bulging disc was identified and confirmed fluoroscopically. A no. 15 blade scalpel was used to incise the annulus, and a discectomy was performed using a series of curettes and pituitary rongeurs. At the completion of decompression, the exiting and traversing nerve roots were noted to be well decompressed throughout their course. Hemostasis was obtained with bipolar cautery and Gelfoam. The wound was copiously irrigated with antibiotic solution and the retractor was removed. Fascia was closed using 0 Vicryl stitches. The subcutaneous tissue was closed using 2–0 Vicryl stitches. Finally, the skin was closed using Dermabond. The patient was then returned to the supine position and allowed to recover from anesthesia.



44.2.6 Postoperative Care


The patient was observed in recovery for 2 hours and was discharged.


44.2.7 Management of Complications


The most common complication in this procedure is incidental durotomy. This can be handled with a dural sealant and 24 hours of bed rest. Lumbar drain is not necessary. The skin can be closed using a running locking nylon suture to help prevent cerebrospinal fluid (CSF) leakage and allow for healing.


44.2.8 Operative Nuances


Microscope can be used instead of an endoscope. Drilling 2 mm of the medial facet facilitates access to the disc with minimal retraction of the nerve root.


44.2.9 Postoperative Results


Excellent results can be expected in 90 to 95% of patients treated with this technique.


44.3 Case 2: Awake Lumbar Minimally Invasive Transforaminal Lumbar Interbody Fusion


44.3.1 Patient Profile


A 62-year-old man presented with severe right thigh and back pain. He had failed conservative measures and was only able to walk three blocks before having to stop. The pain was related to mechanical loading, exacerbated with standing and walking, and relieved with a recumbent position. Epidural injections were helpful, but only gave transient relief.


44.3.2 Case Selection


Radiographic imaging demonstrated a mobile grade I spondylolisthesis at the L3/L4 level due to an old bilateral pars defect (image Fig. 44.2a,b).


44.3.3 Preoperative Notes


The patient was offered anterior versus posterior versus combined (360-degree) approaches. He elected for a posterior approach, which was more likely to achieve a successful reduction and fixation in a single-stage operation. Additionally, the patient had relatively normal spinal canal diameter at the L3–L4 level and did not require direct decompression to address spinal canal stenosis.


44.3.4 Instrumentation Notes


Accomplishing a percutaneous interbody fusion requires the use of expandable cages that can be placed through Kambin’s triangle. As such, all disc preparation and graft placement must be carried out through a maximum of an 8-mm corridor. Percutaneous screws are placed in standard fashion.


44.3.5 Surgical Approach and Technique


The patient is given sedation with propofol anesthesia but no narcotics. Positioning is prone on a Jackson table. A flank incision is made 12 cm off the midline and access is made into the disc space using the extraforaminal endoscopic approach into Kambin’s triangle. After discectomy and nerve root decompression, disc clearance can be achieved utilizing specialized brushes that do not violate the bony end plate. After disc space preparation, the space is filled with graft material and the interbody expandable cage is inserted. Expansion of the cage allows interbody distraction, spondylolisthesis correction, fusion, and indirect decompression of the contralateral nerve root with disc and foraminal height restoration (image Fig. 44.2f). Percutaneous screws are then placed after injecting the screw tracts with long-acting local anesthetic medications.


44.3.6 Postoperative Care


The patient is managed postoperatively with standard pain management and bracing, similar to standard open surgery.


44.3.7 Management of Complications


Routine antibiotic prophylaxis is used to minimize the risk of postoperative infections. Pseudarthrosis can be minimized with proper graft site preparation, use of appropriate graft materials, bracing, external bone stimulation, and the elimination of tobacco use.


44.3.8 Operative Nuances


Performing this procedure without a general anesthetic requires careful attention to patient selection, preserving soft-tissue structures, use of expandable cages, specialized percutaneous screws placed through smaller incisions, and the use of long-acting local anesthetics. In addition, thoughtful coordination with the anesthesiologist is key.



44.3.9 Postoperative Results


Patients treated in this manner can be discharged after one night in the hospital and opioid usage is minimal.


44.4 Case 3: Mini-open Pedicle Subtraction Osteotomy


44.4.1 Patient Profile


A 57-year-old woman presented with difficulty standing, walking, and working due to intractable low back pain. She had lost 3 inches of height over the past 4 years. Imaging revealed the patient had a degenerative kyphoscoliosis, consistent with her symptoms (image Fig. 44.3a).



44.4.2 Case Selection


The goals of spinal realignment and fusion/fixation are central to the proper treatment of this patient. However, the application of standard open deformity surgery carries a significant complication rate. Thus, the patient elected for a less invasive option with the same surgical corrective goals.


44.4.3 Preoperative Notes


Careful counseling for the treatment of osteopenia and osteoporosis is common in this patient population. In addition, higher rates of pseudarthrosis and proximal junctional kyphosis are seen when treating adult spinal deformities.


44.4.4 Instrumentation Notes


The technique of mini-open pedicle subtraction osteotomy (PSO) necessitates placement of a lordotic rod through a kyphotic spine. Use of four rods (two passed from above and two from below) achieves this objective.


44.4.5 Surgical Approach and Technique


After positioning the patient on a Jackson table, a dorsal midline skin incision is made. However, the deeper soft tissues are dissected only at the level of the PSO. Thus, this exposure is similar to an open two-level lumbar fusion. Interbody fusion is performed below the level of the PSO using the MIS transforaminal lumbar interbody fusion (TLIF) technique. The L3 level PSO is performed in standard fashion with spinous process, lamina, and facet removal. This is followed by pedicle removal and a bilateral de-cancellation osteotomy using a series of enlarging curettes to remove two cones of cancellous bone from the vertebral body. Central bone was removed with a curved curette and the de-cancellation is extended superiorly into the L2–L3 disc space. A Leksell rongeur is then used to remove the lateral vertebral body wall bilaterally in a wedge-shaped pattern to match the de-cancellation. Control of the spine to break the osteotomy is then achieved by placing percutaneous pedicle screws at least three levels above and below the PSO site. A total of four rods are bent and passed through each set of screw heads above and below the PSO. The posterior vertebral body wall and posterior longitudinal ligament are removed, and after ensuring there is no ventral bone or ligament that might impinge on the thecal sac, the osteotomy is closed (image Fig. 44.3c). The L3 nerve roots and thecal sac are then inspected to ensure that there is no neural compression, and any bleeding is controlled with powdered collagen matrix. The cranial and caudal rods are connected with offset connectors, and the construct is finally tightened and fusion of the facets above the PSO is achieved through small access sites (image Fig. 44.3d,e).


44.4.6 Postoperative Care


The patient is managed postoperatively with standard pain management and bracing, similar to standard open surgery.


44.4.7 Management of Complications


As with open osteotomies and deformity corrections, these patients are subject to risks associated with bleeding, nerve root compression, pseudoarthrosis, and spinal misalignment.


44.4.8 Operative Nuances


Great care must be taken to connect the four rods properly and also to bend them to the proper degree of lordosis.


44.4.9 Postoperative Results


In a series of patients treated in this manner, significant reductions in blood loss were made possible by reducing the amount of soft-tissue dissection and subperiosteal exposure.


44.5 Case 4: Minimally Invasive Lateral Lumbar Interbody Fusion


44.5.1 Patient Profile


A 56-year-old woman with history of multiple motor vehicle accidents (MVA) and falls presented with 3 years of low back pain, radiating bilaterally to her lateral thighs, calves, and ankles (image Fig. 44.4).


44.5.2 Case Selection


Two-level spondylolisthesis with back pain equal to or greater than radicular pain suggests that fusion, rather than just decompression, is the better option for this patient. MIS techniques include TLIF or lateral lumbar interbody fusion (LLIF). In this case, LLIF seems to be the less invasive technique, and enables more rapid recovery.


Oct 17, 2019 | Posted by in NEUROSURGERY | Comments Off on Minimally Invasive Spine Surgery: Lumbar Case Studies
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