Surgical Tips, Tricks, and Techniques to Minimize Invasiveness; General Advice on How to Handle Fluoroscopy, Blood Loss, and Infection Rates

15 Surgical Tips, Tricks, and Techniques to Minimize Invasiveness; General Advice on How to Handle Fluoroscopy, Blood Loss, and Infection Rates

Eric H. Elowitz

Summary

Surgical tips, tricks, and techniques to minimize invasiveness are reviewed with special emphasis on how to handle fluoroscopy, blood loss, and infection rates. Minimally invasive spine surgery (MISS) offers many potential advantages for patients. However, for the surgeon, there are unique considerations to best achieve the successful performance of these lesser invasive surgeries. Thorough preoperative planning, patient selection criteria, and review of radiological studies are critical. Additionally, there is typically a reliance on intraoperative imaging, including fluoroscopy or computerized-image guidance, requiring the surgeon to have an additional level of technologic sophistication. Avoidance of blood loss and a knowledge of vascular anatomy are also essential. Although the infection rate has been shown to be lower with minimally invasive surgeries than more conventional spine procedures, attention to proper sterile technique in the operating room has particular challenges in minimally invasive procedures.

Keywords: minimally invasive spine surgery fluoroscopy radiation exposure infection incision planning surgical navigation

The topics discussed in this chapter are relevant for a variety of procedures and pathologies encountered in MISS. A seasoned expert in MISS provides valuable pearls that are relevant for surgeons at any stage of the procedure; especially preoperative planning and careful patient and procedure selections are stressed. Overall, a surgeon’s attention to detail is critical for successful MISS.

15.1 Introduction

Over the past several decades, minimally invasive techniques for spine surgery have gained acceptance and increased popularity.1 Advancements in technology, as well as unique approaches to the spine, have fueled the growth in this area. More and more surgeons are adopting these techniques in their practice for the benefit of their patients. As has been widely quoted, minimally invasive spine surgery (MISS) techniques involve smaller incisions,² less muscle dissection and trauma,³^,⁴ shorter hospital stays,⁵ and decreased infection rates.⁶^,⁷ However, as with all new surgical areas, MISS does offer unique challenges. The learning curve can often be lengthy and may temporarily increase complication rates.⁸ New technologies must be evaluated with long-term outcomes. Over time, MISS techniques need to be validated and be shown to be equivalent, or superior, to more conventional approaches.

In many ways, MISS techniques require a mindset in practitioners of innovation and technique advancement. The safe performance of these procedures offers unique challenges. Although the incisions may be smaller, often multiple incisions are required. Change of patient position under anesthesia also has potential risks. The intraoperative setup and positioning time is frequently lengthier than conventional, open spine surgery. Additionally, the need for fluoroscopy, and other image guidance, requires a technological sophistication on the part of the surgeon as well as a reliance on radiology technologists and the proper operation of this equipment. Successful performance of MISS requires a great attention to detail. Surgeons must have a willingness to use and adapt new technologies and techniques for the benefits of their patients and the advancement of spinal care.

15.2 Patient Evaluation and Selection

The key elements to successful spine surgery start well before the day of surgery. Patient history, physical examination, and evaluation of radiological imaging must be carefully considered. Nonsurgical treatment is often recommended initially for patients with pain and degenerative spinal conditions; however, based on the imaging and clinical status of the patient, surgery may be offered. It is important to listen to patients in order to ascertain their concerns and goals of treatment when surgery is being considered. Frequently, a frank discussion between the patient and surgeon is necessary to help guide a shared-decision process.

The overall condition and age of the patient are important presurgical considerations. For example, older patients who have spinal stenosis and a minimal spondylolisthesis may be appropriate candidates for a simple tubular decompression, while younger, more active, patients may be more appropriate for a spinal fusion. Additionally, evaluation for any prior spine surgery is necessary.

A thorough evaluation of radiological imaging is also a requirement. The pathology demonstrated needs to be correlated with a patient’s complaints and physical findings. Frequently, multilevel spinal pathology is present and clinical judgment is required to best determine which levels may be responsible for the patient’s symptoms. In some cases, the decision may be made to treat just the perceived symptomatic level while in other patients, a more global approach to the spinal problem would be optimal.

Magnetic resonance imaging (MRI) is the mainstay for spine evaluation. Additionally, there are many instances where computed tomography (CT) can be of benefit; in situations where there is concern for bony anatomy, or if there has been prior surgery, CT scanning may be helpful. For patients who have had prior spinal instrumentation, CT may be used to evaluate the degree of fusion as well as hardware positioning. X-ray imaging also plays a role, particularly when dynamic views are ordered; flexion-extension X-rays can be of benefit to evaluate a mobile spondylolisthesis. Full-body scoliosis films are ordered to evaluate global coronal and sagittal balance (Fig. 15.1). Recently, there has been a greater appreciation of the role of proper spinal alignment for successful surgical outcomes.⁹

Fig. 15.1 Full-spine scoliosis films are ordered to evaluate global coronal and sagittal balance: (a) anteroposterior (AP) image; (b) lateral image.

When considering surgery for a patient, the goals of surgery should be clearly considered. Commonly this includes a decompression when there is impingement of neural structures. Fusion, in cases of instability or extensive planned bone removal, may be a goal. Proper correction of spinal alignment, or restoration of disc height, may also be goals to be considered. For the spinal surgeon who favors MISS, it is necessary to consider whether the goals of the surgery can be accomplished through these lesser invasive surgeries; even for the experienced MISS surgeon, not all pathologies can best be fully addressed using these techniques and more conventional open approaches may need to be considered. It is critical to configure the MISS techniques to the goals of surgery rather than vice versa; a surgeon should not readjust the surgical goals just for the sake of making a surgery smaller.

In preoperative evaluation and selection, there are many situations where special considerations are necessary. As an example, in patients who are being considered for a lateral lumbar interbody fusion (LLIF), it is critical to ask whether they have had prior abdominal or retroperitoneal surgery; for patients who have had major abdominal surgeries, a different approach may be best advised to reduce the risk of bowel injury. Additionally, patients who have had previous surgeries should be physically examined in order to assess their prior wounds for proper healing as well as planning of any subsequent incisions.

15.3 Preoperative Planning

It has been said, “A surgery can fail even before the patient arrives in the operating room.” For the successful performance and outcome of any surgery, thoughtful preoperative planning is required. MISS has unique considerations and often requires additional preoperative planning. The surgeon must visualize, in advance, the surgery itself as well as the needs of the operation. MISS often requires significant equipment and technology, and this needs to be considered and ordered well before the surgical date.

Some MISS surgeons may use a mental, or even a physical, checklist to prepare for a surgery. Some of the important considerations are:

•Approach.

•Patient positioning.

•Equipment.

•Personnel.

•Equipment placement.

•Intraoperative imaging.

•Intraoperative neurophysiology monitoring.

•Bone for fusion.

•Navigation.

•Postoperative care.

15.4 Incision Planning and Tubular Considerations

Conventional lumbar spine surgery generally involves a single midline incision with significant muscle dissection and retraction. However, MISS employs smaller, but often multiple, incisions to approach the spine. As the incisions are smaller and the corridors to the spine more limited, in many ways, the incision location is even more critical than in open surgery. Intraoperative MISS incision planning requires the use of image guidance, either fluoroscopy or computerized navigation.

Tubular retractors are frequently employed during MISS. The benefit of these retractors is that incisions are not only smaller but also they use dilation rather than cutting of muscle.3 The length of the skin incision is dependent on the size of the tube being used. Although smaller incisions are clearly preferable, it is important to keep the incision adequate enough to avoid excess pressure on the skin edges, which can lead to necrosis and poor wound healing. In my experience, a 16- or 18-mm tube is appropriate for microdiscectomies while a 22-mm tube is used for decompressive laminectomies. Spinal endoscopy often requires little more than a stab incision.

The side of approach is another important preoperative planning decision. Although the incision is often ipsilateral to the side of the pathology, such as a paracentral herniated disc, there are situations where a contralateral approach may be considered. Some authors have advocated the use of a contralateral tubular approach for the resection of lumbar synovial cysts.¹⁰ In LLIF procedures, the incision and side of approach may be contralateral to the patient’s symptoms if there is a scoliosis or partial disc collapse; in some cases, the relationship of the disc space to the iliac crest may dictate the side of approach. Also, anterior cervical discectomy incisions are frequently contralateral to the patient’s radiculopathy. In all surgeries where the planned incision is contralateral to the patient’s symptoms, a discussion with the patient prior to surgery is helpful to avoid the misperception of a “wrong”-sided approach.

In tubular MISS, the incision’s lateral distance from the spine also needs to be planned. An endoscopic discectomy may require an incision almost at the midline in order to gain more lateral visualization through the endoscope. For a tubular microdiscectomy, the incision is generally 1 cm lateral to midline; however, for an extraforaminal approach, where tube docking is performed on the pars interarticularis, a 2 cm distance is preferred.11

15.5 Incision Planning for Lumbar Fusions

Lumbar spinal fusions performed using MISS techniques offers benefits to the patient over conventional, open surgery.¹^,¹² There are several different possible approaches and the surgical plan should be customized depending on the needs of each patient. One of the first MISS techniques described, the MISS transforaminal lumbar interbody fusion (TLIF),² is routinely performed via a slightly lateral incision, approximately 3 cm off midline. Contralateral pedicle screws are placed through a separate incision.

The percutaneous placement of pedicle screws is a common MISS procedure. However, the nature of the skin incisions can vary. For a one- or two-level fusion, a lateral incision, frequently 3 cm off the midline, is performed. At the lower lumbar levels (L4/L5 and L5/S1), a single lateral incision is usually performed on each side as the lumbar lordosis brings the percutaneous entry points very close. However, in the middle and upper lumbar levels (such as L2/L3 and L3/L4), smaller separate incisions may be employed and the rod passed under the skin and fascia. In cases of multilevel fusion with percutaneous screw placement, some authors advocate for a single midline skin incision and multiple lateral fascial incisions.¹³ This is particularly the case in multilevel percutaneous screw placement for deformity correction.

In LLIF surgery, skin incision placement is also critical. The skin incision is marked out with the use of lateral and anteroposterior (AP) fluoroscopy to gain a direct trajectory to the disc via the tubular retractor path. This will prevent being off-plane to the disc, which could compromise interbody graft placement. It is this surgeon’s bias that for a single LLIF a transverse incision is performed, while in a multiple level LLIF, a longitudinal skin incision is performed with separate transverse fascial incisions.

15.6 Fluoroscopy/Radiation Exposure

As MISS is highly dependent on small incision and frequently tubular approaches, image guidance is a necessity. Most surgeons rely on intraoperative fluoroscopy for tube placement as well as pedicle screw trajectory. The use of fluoroscopy does pose a risk of continued and frequent radiation exposure to the spine surgeon and operative team. There have been many reports describing the potential health risks to the operating room personnel related to radiation exposure.¹⁴^,¹⁵

It is critical that all of the operating room personnel wear protective radiation shields and, in particular, thyroid collars. One drawback to heavy lead gowns is the length of time that many of these procedures require by placing physical strain on the staff. Lighter weight materials that are protective are now available.¹⁶ Radiation protective glasses should also be considered, particularly in procedures employing multiple fluoroscopy images, such as percutaneous pedicle screw placement. Radiation exposure to the eyes has been linked to early cataract development.¹⁷ Some surgeons use radio-opaque gloves to minimize radiation exposure to their hands, although the thickness of these gloves can diminish tactile feedback.

Other strategies can be used to minimize radiation exposure to both the patient and operative team.¹⁸ Live fluoroscopy should be used only selectively and, in fact, is rarely needed in MISS procedures. The use of magnification on the fluoroscope significantly increases the radiation dose and should be limited. Thoughtful use of fluoroscopy in order to minimize the number of images obtained is also important. Collimation of the field is another effective way of limiting radiation and may improve image quality as well (Fig. 15.2). Newer technologies, such as LessRay (NuVasive, San Diego, CA), are being developed to reduce radiation exposure.