Disc degeneration in the cervical spine that requires surgical intervention is historically treated by removing debris and/or performing an anterior cervical discectomy and fusion (ACDF), removal of the disc and fusion of the bones. Although this has been fairly effective, the treatment affects the patients’ range of motion and often needs further surgery in neighboring discs. Current statistics identify the rate as 2.9 percent every year, with 25.6 percent of patients requiring repeat surgery within 10 years of the first surgery.
Researchers have also found that another complication, pseudoarthritis, which affects the local tendons and ligaments, also occurs frequently. One previous study has shown that the pseudoarthritis rate is related to the number of discs fused (levels). As well, the bone for the fusion is harvested by the surgeon from the patient’s iliac crest (the edge of the hip bone), and this results in complications (pain, infection, nerve pain in the thigh, and bone fracture) in between one percent and 25 percent of the patients.
The authors of this study investigated the use of a replacement disc, the BRYAN Cervical Disc Prosthesis, compared with the standard ACDF treatment in 115 patients (32 men) at 3 centers. Fifty-six patients received the implant and 59 the fusion. The average age of the patients was 42 years for the replacement and 46 for the fusion.
In order to evaluate the patients’ ability to function and levels of pain, the researchers used the Neck Disability Index (NDI), the Arm Pain Score (VAS), Neck Pain Score (also VAS), and the Short form 36 (SF-36). The patients were assessed before surgery and again at six weeks, three months, six months, 12 months, and 24 months after surgery. X-rays were also done for visual assessment.
When reviewing the findings, the researchers found the prosthesis performed favorably compared with the ACDF. The physical component, measured by the SF-36 was, on average, 56 in the prosthesis group and 59 in the control group, before surgery. This remained at 56 and 59, respectively, at six weeks, but began to drop, indicating improvement, to 54 and 57 (respectively) at three months and 36 and 35 at 24 months. In the mental component, the numbers were similar. Before surgery, the NDI scores for pain in the prosthesis group were rated, on average, at 56, the control group at 59. The pain scores improved steadily, dropping to 54 and 57 (respectively) at three months and 36 and 35 at 24 months. Finally, the neck pain scores, before surgery, were on average 56 in the prosthesis group and 58 in the control group, dropping to 49 and 54, respectively, at six months, and 36 and 35 at 24 months.
Some patients did experience complications during the follow-up period. Three patients in the prosthesis group and four in the control group needed further surgery. In the control group, one required a fusion, another a revision ACDF that was followed by another surgery for fusion, and two more required further ACDF for neighboring levels that had begun to deteriorate. In the prosthesis group, the three required ACDF for neighboring levels.
The authors write that their findings were similar to previous study findings, although there were differences in the study itself. For example, one previous study did not have a control group. They concluded that the BRYAN Cervical disc prosthesis compares favorably with ACDF.