Total Disc Replacement Complications

Cervical arthroplasty, a surgical intervention for cervical spine issues, can be associated with complications stemming from patient selection and surgical technique. Certain patients with specific conditions may not be appropriate candidates for the procedure and may experience complications.

Errors during surgery can lead to problems such as implant sinking, implant dislodgement, nerve-related symptoms, spinal curvature, and abnormal bone growth. This article focuses on the unique complications of cervical arthroplasty and provides a comparison of these complications between cervical total disc replacement (cTDR) and anterior cervical discectomy and fusion (ACDF) procedures.

Implant Sinking, Dislodgment, Displacement, And Bone Loss

Possible complications of cervical arthroplasty include implant sinking (subsidence), implant movement or dislocation, persistent nerve root symptoms (residual radiculopathy), and rare cases of osteolysis.

Subsidence can lead to neck pain and nerve compression, and its occurrence rates vary in the available literature. Patients with osteopenia or osteoporosis have a higher risk. Suboptimal surgical techniques like violating the end plates or using undersized implants can contribute to subsidence.

Insufficient decompression during the procedure can result in ongoing radicular symptoms. Osteolysis, although uncommon, can arise from wear debris or an immune response, especially when metal-on-metal devices are used.

Addressing complications such as subsidence, expulsion, dislocation, and osteolysis usually involves undergoing revision surgery with anterior approaches, where the device is removed and converted to fusion, either through ACDF or anterior corpectomy.

On the other hand, recurrent radiculopathy caused by recurrent or residual foraminal stenosis can typically be treated with a posterior minimally invasive laminoforaminotomy. This procedure is also minimally invasive and preserves motion.

Heterotopic Ossification

Heterotopic ossification (HO) is characterized by the abnormal formation of bone outside the skeletal system, which can arise as a complication after arthroplasty procedures.

This condition can lead to restricted joint movement and, in some cases, fusion of the affected joint. Various risk factors have been identified, including advanced spondylosis, osteophytic disease, male gender, and older age. To minimize the occurrence of HO, it is crucial to undertake careful patient selection, employ precise surgical techniques, and ensure the use of appropriately sized implants.

When selecting patients for arthroplasty, it is important to consider the presence of risk factors that may predispose individuals to develop HO. Surgeons should follow meticulous surgical techniques, which involve thorough irrigation during drilling and the use of bone wax when necessary to prevent exposure of cancellous bone.

Optimal implant sizing is also important, as choosing implants that adequately cover the end plates can help reduce the risk of HO. It is noteworthy that HO typically does not produce noticeable symptoms, thereby rendering revision surgery unnecessary in most cases. Instead, the focus lies on implementing preventive measures and closely monitoring patients for any potential complications associated with HO.

Adjacent Segment Disease

Adjacent segment disease is characterized by degenerative changes in spinal segments adjacent to a previously fused spinal level. It can cause symptoms like radiculopathy, myelopathy, or mechanical instability.

The introduction of motion-preserving devices aimed to reduce stress on adjacent segments, potentially decreasing the occurrence of adjacent segment disease compared to fusion. However, the development of this condition is influenced by various factors, including the underlying degenerative process, patient selection, surgical technique, and the number of levels treated.

While arthroplasty may show promise in reducing adjacent-level degeneration and disease compared to fusion, further research is necessary to gain a comprehensive understanding of its effectiveness.

Research conducted on cadavers has shown that artificial disc placement decreases stress on neighboring segments in comparison to simulated fusion. Initial findings from studies examining adjacent segment degeneration after artificial disc replacement revealed no signs of degeneration during a 5-year follow-up.

A meta-analysis involving FDA Investigational Device Exemption (IDE) studies, which encompassed three randomized multicenter trials, exhibited a notably reduced incidence of adjacent-level surgery favoring arthroplasty.

Supporting evidence from a thorough meta-analysis further confirmed the lower occurrence of adjacent segment degeneration and reoperation in favor of arthroplasty. Long-term studies with follow-up durations of up to 84 months have demonstrated the potential for reduced rates of adjacent-level degeneration and reoperation with arthroplasty.

For instance, a study involving the SECURE-C device revealed a significantly lower incidence of adjacent segment reoperation in the arthroplasty group compared to the anterior cervical discectomy and fusion (ACDF) group.

Likewise, investigations involving the Prestige ST Disc and Mobi-C device have shown decreased incidences of adjacent segment degeneration and subsequent surgeries in the arthroplasty groups compared to ACDF.

These results provide further evidence supporting the idea that arthroplasty may be linked to a decreased risk of adjacent segment degeneration and the requirement for additional surgical interventions, both at the treated level and neighboring segments.

Dysphagia

Dysphagia, characterized by difficulty swallowing, is a frequent complication that can arise after anterior cervical surgery. While the precise causes remain unclear, they are likely influenced by multiple factors.

Age, duration of degenerative disease, operative time, blood loss, multilevel surgery, diabetes, and smoking have been identified as predictors of dysphagia. Immediately after surgery, dysphagia rates are typically high, with no significant disparity observed between cervical arthroplasty and anterior cervical discectomy and fusion (ACDF) in most studies.

However, some studies indicate a potentially lower occurrence of dysphagia with arthroplasty. A meta-analysis concluded that ACDF does not demonstrate superiority over arthroplasty across various outcome measures.

To minimize the likelihood of dysphagia during anterior cervical exposure, it is advised to utilize well-established techniques. These strategies involve ensuring careful control of bleeding, positioning retractors in the longus colli muscles and periodically releasing them every 15 to 20 minutes, conducting thorough release of muscles and soft tissues during dissection (including potential removal of the omohyoid muscle), deflating the endotracheal cuff after retractor placement, maintaining adequate blood flow in the superficial temporal artery following retraction, and administering corticosteroids perioperatively.

Complications Related to Blood Vessels and Risk of Infection

Adverse vascular events and surgical site infections are infrequent in anterior cervical surgery. Comparisons between arthroplasty and anterior cervical discectomy and fusion (ACDF) have shown minimal blood loss with no substantial disparity between the two procedures.

Although isolated cases of intraoperative vascular injuries have been reported, the overall incidence of surgical site infections remains minimal. Consistent findings across various studies comparing arthroplasty and ACDF have highlighted low rates of vascular events and infections.

Dysphagia, the most common complication, is not associated with a higher risk in arthroplasty compared to anterior cervical discectomy and fusion (ACDF). Complications related to the anterior cervical approach are infrequent and display similar occurrence rates in both ACDF and cervical total disc replacement (cTDR). Rates of vascular complications and infection are low, with no significant differences observed between ACDF and arthroplasty.

Precise patient selection and surgical technique can help mitigate complications associated with cervical artificial disc placement, such as subsidence, displacement, osteolysis, and heterotopic ossification (HO), although these occurrences are rare. Cervical arthroplasty is most suitable for patients with 1- to 2-level cervical soft disc disease, mild spondylosis, and no significant facet disease or osteoporosis.

Surgical techniques may vary depending on the chosen implant, but they typically involve accurate midline verification, symmetrical decompression with resection of the proximal uncovertebral joint, minimal drilling, preservation of the bony end plates, appropriate implant sizing, and placement close to the disc’s natural center of rotation. In the event of failed cervical disc arthroplasty, revision surgery is typically straightforward and tailored to address the specific cause of failure.

The development of adjacent segment disease can be observed after arthroplasty or arthrodesis surgeries, and it is influenced by various factors. Biomechanical research has demonstrated that artificial disc placement decreases the stress on neighboring levels in comparison to fusion.

The clinical significance of these reduced stresses is still a matter of discussion. Nevertheless, several meta-analyses and long-term studies indicate that cervical arthroplasty might be associated with a lower occurrence of adjacent segment degeneration and disease.