The use of stand-alone interbody devices for ALIF has been met with mixed clinical success. As a result, many supplement ALIF with posterior spinal fixation with or without posterior intertransverse fusion (360° or circumferential fusion) to increase stabilization, enhance arthrodesis, and ideally improve clinical outcomes (Fig. 28.2a, b). The use of supplementary posterior fixation has been demonstrated to improve stabilization in multiple directions and increase fusion. Holte et al. [13] found that FRA combined with posterior spinal instrumentation resulted in a 98 % fusion rate compared to a 75 % fusion rate with stand-alone FRA. A recent study using thin-section computed tomography revealed an 89 % fusion rate with pedicle screw–rod fixation compared to a 51 % fusion rate with stand-alone ALIF [14].

Transpedicular fixation with a pedicle screw–rod construct remains the biomechanical gold standard for internal stabilization. Pedicle screws when affixed to a connecting rod have the unique capacity for three-dimensional control with restriction of motion in all planes. Conventional open pedicle screw placement, however, adds considerably to the morbidity of the surgical procedure. Besides a separate posterior incision, extensive muscle dissection and retraction is necessary to visualize the appropriate anatomic landmarks for pedicle screw placement. This can result in increased tissue injury, blood loss, operative time, postoperative pain, recovery period, and potential for nerve root or facet injury.

Alternative less invasive options for posterior spinal fixation exist. Translaminar facet screws are placed either via a mini-open technique or percutaneously over a guide wire, thereby reducing operative morbidity. A study investigated fusion rates for patients undergoing either stand-alone ALIF or ALIF with either translaminar, unilateral pedicle, or bilateral pedicle screw constructs. Thin-section computed tomography was used to assess for radiographic evidence of fusion. Patients undergoing unilateral or bilateral pedicle screws had higher fusion rates (89 % and 88 %, respectively) compared to translaminar screw (58 %) fixation or stand-alone ALIF (51 %) [14]. Alternatively, Best and Sasso [15] found that translaminar screws were associated with decreased pain scores, fewer complications, and decreased incidence of reoperation compared to pedicle screws. Recently, percutaneous transpedicular screw fixation has been developed that allows for percutaneous placement of cannulated pedicle screws over a guide wire. Novel instrumentation has been designed to allow for percutaneous insertion of a connecting rod. The long-term benefit of percutaneous pedicle screws compared to conventional open pedicle screws in terms of stabilization, enhancing fusion, and operative morbidity, however, remains to be determined.

In 1959, Humphries et al. first reported the use of an anterior lumbar plate to stabilize the motion segment after ALIF. Until recently, anterior lumbar plate fixation, however, did not gain popularity due to several factors. The primary concern was that obtaining access for application of the implant was limited due to surrounding vascular, gastrointestinal, and urologic structures. Implants that provided sufficient stability were often too bulky or cumbersome. Additionally, problems with device migration and screw backout plagued many of the early iterations of such instrumentation. Recently, however, lower profile anterior lumbar screws and plates have been designed which achieve better screw–bone purchase by fixating the cortical bone of the apophyseal ring. More recently composite devices which incorporate anterior screws through an interbody cage allow for an even lower profile design, effectively eliminating the offset of the anterior plate as well as providing direct fixation of the cage to the adjacent vertebral bodies. As a result, the use of anterior lumbar fixation combined with ALIF has increased in popularity, largely due to the benefit of a single anterior approach technique.

Anterior plate fixation with an interbody device improves construct stiffness and reduces range of motion compared to a stand-alone interbody construct. Glazer et al. [16] found that in human lumbar cadaveric spines, anterolateral instrumentation enhances stability of a femoral ring allograft. Similarly, Kuzhupilly et al. [17] reported significant improvement of the stability of FRA in extension when anterior crossed screws were inserted through the FRA into the adjacent vertebral bodies. Gerber et al. [18] found that a triangular anterior plate is equivalent to pedicle screw–rod fixation in limiting flexion, extension, axial rotation, and shear forces. However, pedicle screw–rod fixation remains superior to anterior plate fixation in restricting lateral bending [19]. It should be noted that in this study, specimens were tested after diskectomy and bilateral facetectomy, which may not represent the most common clinical scenario in which these devices may be employed. Recent data suggests that a composite device consisting of anterior lumbar screws that thread through an interbody cage into the adjacent vertebral bodies provides equivalent stabilization to an anterior cage with pedicle screw fixation and equivalent if not greater stabilization than ALIF with translaminar facet screws (Fig. 28.3a, b).

Complications associated with ALIF can be divided into those related to the surgical exposure and those that occur with diskectomy, graft insertion, and hardware placement. Most intraoperative complications of concern during ALIF are associated with the surgical approach, because with appropriate exposure, potential problems with diskectomy, graft insertion and hardware placement are generally minimized. In fact, one of the main advantages of the ALIF approach is that effective anterior exposure facilitates disk removal, endplate preparation, insertion of a biomechanically optimal graft or device, and placement of anterior fixation if necessary, while protecting the neural elements and surrounding dura.

The list of critical structures at risk in the abdomen and retroperitoneum during surgical exposure for ALIF is lengthy. These include the psoas muscle, small intestine, colon, rectum, bladder, kidneys, ureters, diaphragm and crura, medial arcuate ligament, esophageal hiatus, thoracic duct, lumbosacral plexus, greater splanchnic nerves, phrenic nerves, sympathetic chain, superior and inferior hypogastric plexus, aorta, vena cava, segmental and radicular arteries, common iliac vessels, iliolumbar veins, and medial sacral artery.