Study Design. Retrospective analysis using data from randomized clinical trials.Objective. To compare the occurrence of heterotopic ossification ( HO) between two cervical disc prostheses. Clinical... Show moreStudy Design. Retrospective analysis using data from randomized clinical trials.Objective. To compare the occurrence of heterotopic ossification ( HO) between two cervical disc prostheses. Clinical outcome and range of motion (ROM) were also evaluated.Summary of Background Data. Cervical arthroplasty was reported to be able to maintain the segmental ROM. However, controversy exists since the difference of the occurrence of HO concerning cervical prosthesis is still huge.Methods. Patients who underwent anterior cervical discectomy with arthroplasty for a cervical radiculopathy due to a herniated disc from the The Netherlands Cervical Kinematics (NECK) trial (activC; metal endplates with a polyethylene inlay and a keel for primary stability) and the PROCON trial (Bryan; metal-on-polymer with titanium coated endplates without a keel) were analyzed for HO at 12 and 24 months postoperatively. HO was scored according to the McAfee- Mehren classification. Segmental ROM was defined by a custom developed image analysis tool, and global cervical ROM was measured by Cobb's angle. Clinical outcome was evaluated by means of the neck disability index (NDI) as well as physicalcomponent summary (PCS) and mental-component summary (MCS).Results. At 2-year follow-up, the occurrence of HO was 68% in patients treated with the activC prosthesis (severe HO 55%), which was comparable with 85% (P = 0.12) in patients with the Bryan disc (severe HO 44%; P = 0.43). The HO progression was similar between groups. Clinically, the patients had comparable NDI, PCS, and MCS at 2-year follow-up, and comparable improvement of clinical outcomes. The global ROM in the Bryan group (56.4 +/- 10.8 degrees) was significantly higher than in the activC group (49.5 +/- 14.0, P = 0.044) at 2-year follow-up.Conclusion. In comparison of two cervical disc prostheses the development of HO is independent on their architecture. Although global ROM was higher in the Bryan prosthesis group, this difference was not deemed clinically important, particularly because the clinical condition of patients with and without severe HO was comparable. Show less
Study Design. Retrospective analysis using data from RCTs.Objective. This study aimed to report on the incidence of radiological adjacent segment degeneration (ASD) in patients with cervical... Show moreStudy Design. Retrospective analysis using data from RCTs.Objective. This study aimed to report on the incidence of radiological adjacent segment degeneration (ASD) in patients with cervical radiculopathy due to a herniated disc that were randomized to receive cervical arthroplasty or arthrodesis.Summary of Background Data. Cervical disc prostheses were introduced to prevent ASD in the postsurgical follow-up. However, it is still a controversial issue.Methods. Two hundred fifty-three patients were included in two randomized, double-blinded trials comparing anterior cervical discectomy with arthroplasty (ACDA), with intervertebral cage (ACDF), or without intervertebral cage (ACD) for one-level disc herniation. Neutral lateral radiographs were obtained preoperatively, at 1- and 2-year follow-up after surgery. Radiological ASD was evaluated on X-ray and defined by a decrease in disc height and the presence of anterior osteophyte formation on both the superior and the inferior level in relation to the target level.Results. Radiological ASD was present in 34% of patients at baseline and increased to 59% at 2-year follow-up in the arthrodesis groups (ACD and ACDF combined), and to 56% in the arthroplasty group. Progression of radiological ASD was present in 29% of patients in the arthrodesis group and in 31% of patients in the arthroplasty group for 2-year follow-up.Conclusion. Radiological ASD occurs in a similar manner in patients who were subjected to arthrodesis in cervical radiculopathy and in patients who received arthroplasty to maintain motion. Current data tend to indicate that the advantage of cervical prosthesis in preventing radiological ASD is absent. Show less
