Prospective, randomized multicenter study of cervical arthroplasty versus anterior cervical discectomy and fusion: 5-year results with a metal-on-metal artificial disc.

OBJECTIVE Seven cervical total disc replacement (TDR) devices have received FDA approval since 2006. These devices represent a heterogeneous assortment of implants made from various biomaterials with different biomechanical properties. The majority of these devices are composed of metallic endplates with a polymer core. In this prospective, randomized multicenter study, the authors evaluate the safety and efficacy of a metal-on-metal (MoM) TDR (Kineflex|C) versus anterior cervical discectomy and fusion (ACDF) in the treatment of single-level spondylosis with radiculopathy through a long-term (5-year) follow-up. METHODS An FDA-regulated investigational device exemption (IDE) pivotal trial was conducted at 21 centers across the United States. Standard validated outcome measures including the Neck Disability Index (NDI) and visual analog scale (VAS) for assessing pain were used. Patients were randomized to undergo TDR using the Kineflex|C cervical artificial disc or anterior cervical fusion using structural allograft and an anterior plate. Patients were evaluated preoperatively and at 6 weeks and 3, 6, 12, 24, 36, 48, and 60 months after surgery. Serum ion analysis was performed on a subset of patients randomized to receive the MoM TDR. RESULTS A total of 269 patients were enrolled and randomly assigned to undergo either TDR (136 patients) or ACDF (133 patients). There were no significant differences between the TDR and ACDF groups in terms of operative time, blood loss, or length of hospital stay. In both groups, the mean NDI scores improved significantly by 6 weeks after surgery and remained significantly improved throughout the 60-month follow-up (both p < 0.01). Similarly, VAS pain scores improved significantly by 6 weeks and remained significantly improved through the 60-month follow-up (both p < 0.01). There were no significant changes in outcomes between the 24- and 60-month follow-ups in either group. Range of motion in the TDR group decreased at 3 months but was significantly greater than the preoperative mean value at the 12- and 24-month follow-ups and remained significantly improved through the 60-month period. There were no significant differences between the 2 groups in terms of reoperation/revision surgery or device-/surgery-related adverse events. The serum ion analysis revealed cobalt and chromium levels significantly lower than the levels that merit monitoring. CONCLUSIONS Cervical TDR with an MoM device is safe and efficacious at the 5-year follow-up. These results from a prospective randomized study support that Kineflex|C TDR as a viable alternative to ACDF in appropriately selected patients with cervical radiculopathy. Clinical trial registration no.: NCT00374413 (clinicaltrials.gov).

A new treatment paradigm: neoadjuvant radiosurgery before surgical resection of brain metastases with analysis of local tumor recurrence.

PURPOSE: Resected brain metastases (BM) require radiation therapy to reduce local recurrence. Whole brain radiation therapy (WBRT) reduces recurrence, but with potential toxicity. Postoperative stereotactic radiosurgery (SRS) is a strategy without prospective data and problematic target delineation. SRS delivered in the preoperative setting (neoadjuvant, or NaSRS) allows clear target definition and reduction of intraoperative dissemination of tumor cells. METHODS AND MATERIALS: Our treatment of resectable BM with NaSRS was begun in 2005. Subsequently, a prospective trial of NaSRS was undertaken. A total of 47 consecutively treated patients (23 database and 24 prospective trial) with a total of 51 lesions were reviewed. No statistical difference was observed between the 2 cohorts, and they were combined for analysis. The median follow-up time was 12 months (range, 1-58 months), and the median age was 57. A median of 1 day elapsed between NaSRS and resection. The median diameter of lesions was 3.04 cm (range, 1.34-5.21 cm), and the median volume was 8.49 cc (range, 0.89-46.7 cc). A dose reduction strategy was used, with a median dose of 14 Gy (range, 11.6-18 Gy) prescribed to 80% isodose. RESULTS: Kaplan-Meier overall survival was 77.8% and 60.0% at 6 and 12 months. Kaplan-Meier local control was 97.8%, 85.6%, and 71.8% at 6, 12, and 24 months, respectively. Five of 8 failures were proved pathologically without radiation necrosis. There were no perioperative adverse events. Ultimately, 14.8% of the patients were treated with WBRT. Local failure was more likely with lesions >10 cc (P=.01), >3.4 cm (P=.014), with a trend in surface lesions (P=.066) and eloquent areas (P=.052). Six of the 8 failures had an obvious dural attachment or proximity to draining veins. CONCLUSIONS: NaSRS can be performed safely and effectively with excellent results without documented radiation necrosis. Local control was excellent even in the setting of large (>3 cm) lesions. The strong majority of patients were able to avoid WBRT. NaSRS merits consideration in a multi-institution trial.

Prospective randomized study of cervical arthroplasty and anterior cervical discectomy and fusion with long-term follow-up: results in 74 patients from a single site.

OBJECT: The purpose of this study was to evaluate the long-term results of cervical total disc replacement (TDR) and anterior cervical discectomy and fusion (ACDF) in the treatment of single-level cervical radiculopathy. METHODS: The results of 2 separate prospective, randomized, US FDA Investigational Device Exemption pivotal trials (Bryan Disc and Kineflex|C) from a single investigational site were combined to evaluate outcomes at long-term follow-up. The primary clinical outcome measures included the Neck Disability Index (NDI), visual analog scale (VAS), and neurological examination. Patients were randomized to receive cervical TDR in 2 separate prospective, randomized studies using the Bryan Disc or Kineflex|C cervical artificial disc compared with ACDF using structural allograft and an anterior plate. Patients were evaluated preoperatively; at 6 weeks; at 3, 6, and 12 months; and then yearly for a minimum of 48 months. Plain radiographs were obtained at each study visit. RESULTS: A total of 74 patients were enrolled and randomly assigned to either the cervical TDR (n = 41) or ACDF (n = 33) group. A total of 63 patients (86%) completed a minimum of 4 years follow-up. Average follow-up was 6 years (72 months) with a range from 48 to 108 months. In both the cervical TDR and ACDF groups, mean NDI scores improved significantly by 6 weeks after surgery and remained significantly improved throughout the minimum 48-month follow-up (p < 0.001). Similarly, the median VAS pain scores improved significantly by 6 weeks and remained significantly improved throughout the minimum 48-month follow-up (p < 0.001). There were no significant differences between groups in mean NDI or median VAS scores. The range of motion (ROM) in the cervical TDR group remained significantly greater than the preoperative mean, whereas the ROM in the ACDF group was significantly reduced from the preoperative mean. There was significantly greater ROM in the cervical TDR group compared with the ACDF group. There were 3 reoperations (7.3%) at index or adjacent levels in the cervical TDR group; all were cervical laminoforaminotomies. There were 2 adjacent-level reoperations in the cervical TDR group (4.9%). There was 1 reoperation (3.0%) in the ACDF group at an index or adjacent level (a second ACDF at the adjacent level). There was no statistically significant difference in overall reoperation rate or adjacent-level reoperation rate between groups. CONCLUSIONS: Both cervical TDR and ACDF groups showed excellent clinical outcomes that were maintained over long-term follow-up. Both groups showed low index-level and adjacent-level reoperation rates. Both cervical TDR and ACDF appear to be viable options for the treatment of single-level cervical radiculopathy.

Prospective, randomized, multicenter study of cervical arthroplasty: 269 patients from the Kineflex|C artificial disc investigational device exemption study with a minimum 2-year follow-up: clinical article.

OBJECT: Cervical total disc replacement (CTDR) represents a relatively novel procedure intended to address some of the shortcomings associated with anterior cervical discectomy and fusion (ACDF) by preserving motion at the treated level. This prospective, randomized, multicenter study evaluates the safety and efficacy of a new metal-on-metal CTDR implant (Kineflex|C) by comparing it with ACDF in the treatment of single-level spondylosis with radiculopathy. METHODS: The study was a prospective, randomized US FDA Investigational Device Exemption (IDE) pivotal trial conducted at 21 centers across the US. The primary clinical outcome measures included the Neck Disability Index (NDI), visual analog scale (VAS) scores, and a composite measure of clinical success. Patients were randomized to CTDR using the Kineflex|C (SpinalMotion, Inc.) cervical artificial disc or ACDF using structural allograft and an anterior plate. RESULTS: A total of 269 patients were enrolled and randomly assigned to either CTDR (136 patients) or to ACDF (133 patients). There were no significant differences between the CTDR and ACDF groups when comparing operative time, blood loss, length of hospital stay, or the reoperation rate at the index level. The overall success rate was significantly greater in the CTDR group (85%) compared with the ACDF group (71%) (p = 0.05). In both groups, the mean NDI scores improved significantly by 6 weeks after surgery and remained significantly improved throughout the 24-month follow-up (p < 0.0001). Similarly, the VAS pain scores improved significantly by 6 weeks and remained significantly improved through the 24-month follow-up (p < 0.0001). The range of motion (ROM) in the CTDR group decreased at 3 months but was significantly greater than the preoperative mean at 12- and 24-month follow-up. The ROM in the ACDF group was significantly reduced by 3 months and remained so throughout the follow-up. Adjacent-level degeneration was also evaluated in both groups from preoperatively to 2-year follow-up and was classified as none, mild, moderate, or severe. Preoperatively, there were no significant differences between groups when evaluating the different levels of adjacent-level degeneration. At the 2-year follow-up, there were significantly more patients in the ACDF group with severe adjacent-level radiographic changes (p < 0.0001). However, there were no significant differences between groups in adjacent-level reoperation rate (7.6% for the Kineflex|C group and 6.1% for the ACDF group). CONCLUSIONS: Cervical total disc replacement allows for neural decompression and clinical results comparable to ACDF. Kineflex|C was associated with a significantly greater overall success rate than fusion while maintaining motion at the index level. Furthermore, there were significantly fewer Kineflex|C patients showing severe adjacent-level radiographic changes at the 2-year follow-up. These results from a prospective, randomized study support that Kineflex|C CTDR is a viable alternative to ACDF in select patients with cervical radiculopathy.