Lumbar disk arthroplasty uses spinal motion preservation technology for the treatment of degenerative disk disease. Implant design considerations include re-creation of near-normal physiological spinal segment motion by reproducing rotation, translation, and rotation in the disk space, similar to the nucleus of a natural disk. Because proper sizing, placement, and segmental lordosis of the implant are of great importance, selection of core heights, end plate sizes, and end plate angles requires careful consideration ( ▶ Fig. 53.1). Instrumentation that facilitates midline placement allows for optimal performance. When the implant is ideally sized and placed, the lumbar artificial disk implant is designed to (1) preserve near normal physiological motion of the operative spinal segment, which may reduce adjacent-level degeneration ( ▶ Fig. 53.2); (2) maintain segmental stability; (3) restore proper disk height and reestablish segmental lordotic alignment; and (4) reduce diskogenic pain.

The successful treatment of degenerative lumbar disk disease does not depend solely on the implant. It works in concert with additional training in a new technique and proper patient selection.

53.2 Patient Selection

53.2.1 Indications for Use

The first US Food and Drug Administration (FDA)–approved artificial disk implant is the CHARITÉ artificial disk (DePuy Spine, Raynham, Massachusetts), approved in October 2004. The implant design was unchanged until 2010, when the CHARITÉ artificial disk was updated to the INMOTION device, with changes in the fixation spikes and minor changes in the insertion instrumentation. Then in 2012, Synthes and its ProDisc-L were purchased by Johnson & Johnson (New Brunswick, NJ). As part of consolidation process of the extensive spine products of the two companies, Johnson & Johnson retained the ProDisc-L and eliminated both the CHARITÉ and INMOTION lumbar total disk replacement (TDR) product lines. The following discussion is based on lumbar disk arthroplasty using the original CHARITÉ device. Although other implants may have significantly different insertion techniques and indications for use, the general principles first defined for the placement of the CHARITÉ device remain as a guide for the surgical technique of subsequent lumbar TDR designs.

Lumbar disk arthroplasty is indicated in skeletally mature patients with degenerative disk disease (DDD) at one level from L4 to S1, where DDD is defined as diskogenic back pain with degeneration of the disk confirmed by patient history and radiographic studies. Patients undergoing the procedure should have had at least 6 months of unsuccessful conservative treatment before undergoing the procedure. Ideally, patients will not have had other procedures at the level to be treated; however, prior diskectomy, laminotomy/laminectomy (without complete facetectomy), or nucleolysis at the same level to be treated is acceptable.

53.2.2 Preoperative Planning

Patient selection is the most important aspect of successful clinical outcomes in lumbar disk arthroplasty. Preoperative evaluation of the patient’s history, symptoms, and radiologic studies is needed to verify that the suspect lumbar disk is the significant pain generator and that elimination of this pain generator will positively impact the patient’s life. Often diskograms or diagnostic blocks are necessary to verify the site(s) of pain generation. A thorough review of preoperative patient radiologic studies is performed to identify any possible contraindications to disk replacement, as well as to gain a preoperative estimate of the implant size and angle. The details of the surgical approach are coordinated with the spinal access cosurgeon.

53.3 Preoperative Preparation

The patient must be placed supine on a radiolucent operating table that will allow for C-arm imaging in both the anteroposterior (AP) and lateral planes. The hips and knees are in a slightly flexed position to slacken the iliac vessels. The patient’s upper limbs are positioned so that there is space for circumferential C-arm movement over and around the operative level. It is useful to verify the quality of fluoroscopy images before the patient is draped and that movement between the two views is convenient. Intraoperative adjustability of lordosis using a hinged table or inflatable pillow directly under the affected disk is often useful during the implant placement.

53.4 Operative Procedure (See Video 53.1)

53.4.1 Access

Surgical Approach

A left paramedial incision is a commonly used surgical approach. A left paramedian skin incision is made, and retraction of the underlying subcutaneous tissue is performed until the fascia is exposed. This is then divided longitudinally with dissecting scissors. The left rectus muscle is retracted to the left with fingers or blunt retractors. The underlying fascia is raised and divided longitudinally with dissection scissors or blunt dissection. At this stage, the psoas, iliac artery, and iliac vein are identified.

Approach of L5–S1

The L5–S1 intervertebral disk is exposed, and the median sacral vessels are ligated. At this point, further dissection of the tissue anterior to the intervertebral disk is performed mainly by blunt dissection; avoidance of electrocautery is advised to lessen the possibility of parasympathetic plexus damage that can lead to retrograde ejaculation. This dissection is performed for the maximum possible lateral exposure of the disk on both the left and right anterior aspect, taking care to protect the left and right common iliac vessels. Typically, the left common iliac vein and artery are bluntly mobilized with small swabs, and then the right common iliac artery together with the right common iliac vein that lies posterior is mobilized.

The iliac vessels are retracted laterally and occasionally slightly superiorly. Either four retractor pins are placed into the adjacent vertebral bodies as retractors, or a table-mounted external soft tissue retractor system is used. The vertebral level is verified on lateral fluoroscopy. A cautery mark is made at the initial estimate of the coronal midline. Later, the trials are used to accurately identify the midlines. A midline incision opens the anterior anulus. At times, the degenerative disk disease results in thickening of the anterior anulus to greater than 1 cm. This is opened in a slightly funnel fashion, with good visual exposure of the anterior cortical corner required for precise placement of the implant. The flaps of the anulus on strings may be used for protection of eccentric vessels. It should be remembered that table-mounted retractors will cause the patient to roll to the left-hand side a few degrees.

Approach of L4–5

Typically, the bifurcating iliac veins and arteries are mobilized to the right. A similar retraction with four retractor pins or a table-mounted external soft tissue retractor system is used to expose the anterior disk anulus. The vertebral level is verified by lateral fluoroscopy, the approximate midline marked with cautery, and the anterior anulus opened in a leftward motion.

53.4.2 Complete Diskectomy

The initial central diskectomy is performed using rongeurs, curets, and/or the disk elevator. Care must be taken not to damage the bony end plate during the diskectomy. Controlled distraction using the spreading and insertion forceps with release of the posterior anulus is performed to elevate, visualize, and remove the remaining disk tissue, leaving only the lateral anulus and posterior longitudinal ligament. Sequentially, the disk space is distracted using the spacers and modular T-handle through the spreading tips. Parallel distraction is critical for restoration of disk height and sufficient opening of the neuroforamen. The offset tips aid in disk space visualization and surgical diskectomy. If necessary, either or both the guided impactor and slap hammer can be added to aid in insertion or removal.

Performing a complete diskectomy is critical to achieving a successful implant surgery. Complete diskectomy, including removal of the posterior lateral recesses of the disk, (1) provides sufficient space for the optimally sized implant without impacting remaining disk into the neural canal or foramina and (2) facilitates parallel distraction, which provides uniform loading of the implant core, allowing near-normal physiological motion.

53.4.3 End Plate Preparation

The cartilaginous end plate is removed with curets using a side to side motion. Care must be taken not to damage the soft central bony end plate or the structural outer ring of cortical bone. The preserved end plate provides a firm base for mechanical stability and reduces the potential for subsidence.

When necessary, the end plates are carefully shaped to flatten curved vertebral surfaces by removing dorsal and ventral osteophytes and using curets and rongeurs or other appropriate instruments to ensure maximum implant to cortical bone contact area ( ▶ Fig. 53.3).

Related posts:

Expansive Open-Door Laminoplasty for Multilevel Cervical Canal Stenosis Lumboperitoneal Shunting Surgical Treatment of Spinal Intradural Extramedullary Tumors Transcondylar Approach to the Craniocervical Junction Carpal Tunnel Release Endoscopic Carpal Tunnel Release Via a Biportal Approach

Stay updated, free articles. Join our Telegram channel

Join