Introduction

Minimally invasive surgery (MIS) of spinal disorders consists of procedures that aim at reducing the extent of the approach to cause less collateral tissue damage, decrease procedure-related morbidity, and achieve more rapid functional recovery without changing the intended surgical goal. ¹ In the lumbar spine, these aims can often be achieved by three major surgical techniques: a unilateral MIS approach for “over the top” contralateral decompression; minimizing instability using undercutting of spinal anatomy, rather than open surgery, and resection of stabilizing structures; and indirect decompression by implantation of interbody cages. Although the first two techniques are also suitable for the minimally invasive treatment of spinal infections, the third technique is rarely applicable.

Eradication of the underlying infection, restoration of spinal integrity, recovery from neurologic deficits, and pain therapy are the main principles of surgical treatment of spinal infections. ² , ³ The goals of surgical treatment are removal of the septic focus, acquisition of a specimen for microbiological workup, decompression of neuronal structures, and stabilization as well as restoration of the affected spinal segments ⁴ ( Table 13.1 ).

In selected cases, MIS techniques can be used to achieve the surgical goals for the treatment of spinal infections. This is of the highest importance, as patients with spinal infections often suffer from a broad range of medical disorders. In recent years, several studies have been published on MIS strategies for the treatment of spinal infections. Among these strategies are tubular or extreme lateral approaches to the spine, and endoscopic and transpedicular techniques. Additionally, there is increasing interest in percutaneous navigation-guided techniques for the safe and less invasive instrumentation of the affected spinal segments.

Overview of Different Minimally Invasive Techniques

In general, the goals of minimally invasive techniques are a decrease in morbidity and a faster functional recovery by reducing collateral tissue damage through less extensive approaches and by using preformed anatomic corridors. ¹ In accordance with AO Spine principles, the goals of minimally invasive treatment of spinal infections are (1) stabilization of pathological instability, (2) restoration of spinal balance, (3) preservation of neurologic function, and (4) administration of appropriate chemotherapy. ⁵ Based on these principles, there is a multitude of MIS techniques for the treatment of spinal infections using anterior, posterior, and endoscopic approaches ( Table 13.2 ). The choice of the approach should be tailored to the site, the morphology, and the extent and etiology of the pathology. For example, cervical infections are often primarily managed through an anterior approach, endoscopy is widely used for thoracic lesions. In contrast, lumbar infections are often treated posteriorly. More severe infections may require combined approaches or even a 360-degree fusion.

Anterior/Lateral Techniques

Anterior approaches to the spine provide direct access to the most common sites of infection—the vertebral body and the intervertebral disk. Additionally, in cases of a secondary severe deformity, anterior approaches are often required to restore spinal balance and integrity. However, anterior approaches are associated with a significant procedure-related morbidity, particularly in the thoracic and lumbar spine. Therefore, MIS techniques use less extensive approaches (minimally invasive anterior lumbar interbody fusion [ALIF]) or alternative routes to access the anterior column of the spine, such as extreme lateral interbody fusion (XLIF) and direct lateral interbody fusion (DLIF). The literature on the effectiveness of these approaches for the treatment of spinal infections is scarce. However, recently MIS lateral accesses to the anterior vertebral column have gained an increasing interest for the treatment of lumbar degenerative pathologies. Consequently, similar approaches have now been applied for the surgical treatment of spinal infections. In their case series, Lee at al ⁶ retrospectively analyzed the morbidity and clinical outcomes of patients with infectious spondylitis treated with minimal-access lateral approaches compared with traditional anterior approaches. The authors reported a high fusion rate of 97% for both groups and a lower complication rate for the minimal-access group. In 2015, Blizzard et al ⁷ and Patel at al ⁸ published the results of their case series, in which they used an extreme lateral approach for the treatment of spondylodiskitis (specifically XLIF). ⁷ , ⁸ Based on their experiences, they concluded that XLIF may be a safe and effective technique for the treatment of spondylitis. However, it has to be noted that the studies published to date are limited because of small numbers of patients and the lack of information about complications. Nevertheless, these are promising results for the use of MIS techniques in the treatment of spondylitis. The techniques offer sufficiently wide access to the anterior spine while sparing the posterior elements, in particular the erector spinae muscles. This helps reduce the tissue trauma, decrease the blood loss and reduce the operative time, which may be particularly beneficial in a population often presenting in poor medical condition.

In line with the current literature, we recommend adding posterior fixation after lateral or anterior approaches to the spine in patients with spondylitis, as this facilitates early mobilization of patients. The addition of a lateral plate to avoid a posterior fixation may not offer sufficient mechanical support to enable mobilization. Intraoperatively, care should be taken not to violate the end plates to limit cage subsidence. The lateral MIS approach to the spine may also be used to remove adjacent psoas abscesses ( Figs. 13.1 and 13.2 ).