Cervical Artificial Disc Replacement With Discover Prosthesis Does Not Reduce the Midterm Risk of Heterotopic Ossification: Results of a Cohort Study

Failure in cervical total disc arthroplasty: single institution experience, systematic review of the literature, and proposal of the RUSH TDA failure classification system

BACKGROUND CONTEXT

Cervical total disc arthroplasty (TDA) is an alternative procedure to anterior cervical discectomy and fusion that facilitates neural decompression while both preserving motion of the spinal unit and decreasing the risk for degenerative changes at adjacent segments. However, due to its more recent introduction in clinical practice and low complication rates, the modes by which TDA may fail remain to be described.

PURPOSE

This study sought to identify the modes and frequencies of cervical TDA failure in order to propose a novel classification system.

STUDY DESIGN

Retrospective cohort and systematic review.

PATIENT SAMPLE

Patients who underwent single or two-level TDA for cervical radiculopathy or myelopathy at a single institution and in the literature of medium and large prospective studies.

OUTCOME MEASURES

Cervical TDA failure, defined as subsequent surgical intervention at the index segment.

METHODS

This study retrospectively reviewed patients who underwent single or two-level TDA for cervical radiculopathy or myelopathy at a single institution to identify the potential implant failure modes. A systematic review and meta-analysis of prospective data in the literature was then performed to further supplement failure mode identification and to describe the rates at which the various failure types occurred. Statistical analysis included between-group comparisons of Non-Failed and Failed patients and frequencies of each failure type among Failed patients.

RESULTS

A retrospective review at our institution of 169 patients (201 levels) identified eight failures, for a failure rate of 4.7%. Additionally, seven patients were revised who had the primary surgery at an outside institution. The systematic review of 3976 patients (4525 levels) identified 165 (4.1%) additional failures. Using this data, six primary failure types were classified, with several subtypes. These include recurrent or persistent index-level stenosis (Type I); migration (Type II) presenting as gross extrusion (A) or endplate failure with subsidence/acute fracture (B); instability (Type III) due to mechanical loosening (A), septic loosening (B), or device fracture (C); device motion loss (Type IV) such as "locking" of the device in kyphosis; implantation error (Type V) due to malposition (A) or improper sizing (B); and wear (Type VI) either without osteolysis (A) or with wear-particle-induced osteolysis (B). Stenosis (Type I) was the most common mode of failure found both through retrospective review and in the literature.

CONCLUSIONS

Cervical TDA fails through six primary mechanisms. While rates of certain failures requiring subsequent surgical intervention are low, it is possible that these complications may become more prevalent upon further longitudinal observation. Thus, future application and validation of this classification system is warranted to evaluate how failure frequencies change over time and with larger patient samples.

Evaluation of Vertebral Function and Long-Term Quality of Life after Percutaneous Minimally Invasive Surgery in Patients with Thoracolumbar Spine Fractures

OBJECTIVE

To investigate the changes in vertebral function after minimally invasive surgery in patients with thoracolumbar spinal fractures and investigate the impact of percutaneous minimally invasive surgery on patients' quality of life by following up the patients in the long term.

METHODS

A retrospective analysis was performed to select 80 patients with thoracolumbar spinal fractures treated in our hospital from April 2013 to October 2018, and the patients were divided into a study group and a control group according to the difference in their choice of procedure. The two groups were compared in terms of perioperative wound pain, serum creatine kinase (CK) activity, and C-reactive protein (CRP) levels, and the two groups were followed up for 2 years to compare the changes in anterior vertebral body height and Cobb's angle during the follow-up period and to compare the differences in quality of life between the two groups.

RESULTS

(1) The pain level of patients in the study group was significantly lower than that of the control group at the 1st and 3rd postoperative days (p < 0.05). (2) The CK activity and CPR level of patients in the study group were significantly lower than that of the control group at the 1st and 3rd postoperative days (p < 0.05). (3) Compared with the preoperative period, the height of the anterior border of the vertebral body and the Cobb's angle in both groups showed significant changes at 7 d, 6 months, one year, and two years after surgery (p < 0.05), suggesting that both procedures can significantly restore the height of the injured vertebra and improve the function of the vertebral body. (4) The somatic, physical, and psychological functions of patients in the study group were significantly greater than those in the control group at 6 months postoperatively (p > 0.05).

CONCLUSION

Compared to traditional open surgery, minimally invasive percutaneous surgery for thoracolumbar fractures can significantly reduce perioperative pain and improve perioperative stress in patients, while achieving better surgical outcomes and a significantly improved quality of life in patients at long-term follow-up.

Current Status and Prospects of Clinical Treatment of Osteosarcoma

Osteosarcoma, one of the common malignant tumors in the skeletal system, originates in mesenchymal tissue, and the most susceptible area of occurrence is the metaphysis with its abundant blood supply. Tumors are characterized by highly malignant spindle stromal cells that can produce bone-like tissue. Most of the osteosarcoma are primary, and a few are secondary. Osteosarcoma occurs primarily in children and adolescents undergoing vigorous bone growth and development. Most cases involve rapid tumor development and early blood metastasis. In recent years, research has grown in the areas of molecular biology, imaging medicine, biological materials, applied anatomy, surgical techniques, biomechanics, and comprehensive treatment of tumors. With developments in molecular biology and tissue bioengineering, treatment methods have also made great progress, especially in comprehensive limb salvage treatment, which significantly enhances the quality of life after surgery and improves the 5-year survival rate of patients with malignant tumors. This article provides a review of limb salvage, immunotherapy, gene therapy, and targeted therapy from traditional amputation to neoadjuvant chemotherapy, providing a reference for current clinical treatments for osteosarcoma.

Implant Design and the Anchoring Mechanism Influence the Incidence of Heterotopic Ossification in Cervical Total Disc Replacement at 2-year Follow-up

STUDY DESIGN

A nonrandomized, prospective, and single-center clinical trial.

OBJECTIVE

The aim of this study was to determine whether the prosthesis design, and especially changes in the primary anchoring mechanism between the keel-based ProDisc C and the spike-based ProDisc Vivo, affects the frequency of heterotopic ossification (HO) formation over time.

SUMMARY OF BACKGROUND DATA

The occurrence of motion-restricting HO as well as underlying risk factors has so far been a widely discussed, but not well understand phenomenon. The anchoring mechanism and the opening of the anterior cortex may be possible causes of this unwanted complication.

METHODS

Forty consecutive patients treated with the ProDisc C and 42 consecutive patients treated with the ProDisc Vivo were compared with respect to radiological and clinical outcome, with 2 years of follow-up. Clinical outcome scores included the Neck Disability Index (NDI), Visual Analogue Scale (VAS), and arm and neck pain self-assessment questionnaires. Radiological outcomes included the segmental lordosis and range of motion (ROM) of the index-segment as well as the occurrence of HO.

RESULTS

The clinical outcome parameters improved in both groups significantly. [ProDisc C: VAS arm and neck pain from 6.3 and 6.2 preoperatively to 0.7 and 1.3; NDI from 23.0 to 3.7; ProDisc Vivo: VAS arm and neck pain from 6.3 and 4.9 to 1.4 and 1.6, NDI from 34.1 to 8.7; 2-year follow-up (FU)]. The ProDisc Vivo cohort demonstrated a significantly lower incidence of HO than the ProDisc C group at 1-year FU (P = 0.0005) and 2-year FU (P = 0.005). Specifically, high-grade HO occurred in 9% versus 31%.

CONCLUSION

These findings demonstrate that prosthesis designs that allow primary anchoring without violation of the cortical surface help to reduce the incidence of severe ossification, possibly affecting the functionality and mobility of the artificial disc device over of time.

LEVEL OF EVIDENCE

3.

Artificial Discs in Cervical Disc Replacement: A Meta-Analysis for Comparison of Long-Term Outcomes

BACKGROUND

Cervical disc replacement (CDR) has emerged as an alternative to anterior cervical discectomy and fusion for the surgical treatment of degenerative cervical disc disease. Although comparison of the 2 techniques has been studied in the literature, a thorough assessment of all artificial discs between each has not been performed. The objective of the present study was to examine the long-term outcomes of 5 artificial discs.

METHODS

An electronic literature search was conducted for studies of CDR devices for all years available. Only articles in English were included. Heterotopic ossification, adjacent segment disease, and reoperation comprised the primary outcomes of interest. Pooled descriptive statistics with effect size (ES) and 95% confidence interval were used to synthesize the outcomes for each device.

RESULTS

Sixty-five studies (n = 5785) were included in the analysis. Comparison of the incidence of grade III/IV heterotopic ossification showed a significant variability between the 5 devices (P < 0.001) with ProDisc-C (ES, 38%; 95% confidence interval [CI], 24%-54%) having the highest incidence rate. Overall rate of adjacent segment disease was 14% (95% CI, 7%-23%) with significant associated heterogeneity (P < 0.001). Regarding 2-year reoperation risk, the overall incidence rate was 2% (95% CI, 1%-3%), with nonsignificant variability between devices (P = 0.63). The highest rate was observed in the Discover group (ES, 4%; 95% CI, 0%-13%).

CONCLUSIONS

The results of the present meta-analysis indicate that surgical and clinical outcomes may differ among different CDR devices. These findings may assist surgeons in tailoring their decision making to specific patient profiles. Future multicenter efforts are needed to validate associations found in this study.