Treatment of cervical radiculopathy with arthroplasty compared with diskectomy and fusion with cage (ACDF). Clinical, radiological and biomechanical aspects. A randomized multicenter study.

Cervical radiculopathy due to prolapse or spondylosis is a painful condition, and some patients are treated surgically due to persistent pain. The clinical condition is characterized by neck pain with radiating pain in one of the arms, and patients often have accompanying neurological symptoms in the form of numbness and / or weakness. In Norway, approximately 500 patients are operated per year, and when conservative treatment fails, gold standard surgical treatment for symptomatic cervical disc disease is anterior cervical discectomy and fusion (ACDF). Anterior cervical discectomy and arthroplasty (ACDA), aiming to preserve physiological motion at the operated level, was introduced as an alternative to fusion, and has over the last decade gained growing interest among surgeons. This project explores differences in clinical outcome between the two treatment modalities two years after surgery, and investigates post-surgery radiographic challenges with the motion preserving arthroplasty device. The study was designed as a randomized, single-blind, national multi-center study in which all departments in Norway that operates cervical radiculopathy participated. In total 136 patients (63 men and 73 women) were included and randomized to either ACDF (n = 68) or ACDA or (n = 68). The study showed excellent clinical outcome for both arthroplasty and fusion, and no significant between-group difference at any scheduled follow-up. However, the rate of index level reoperations was higher and the duration of surgery longer with arthroplasty. This project also evaluated the degree of heterotopic ossification (HO) among ACDA operated patients and in paper II high-grade HO including spontaneous fusion was seen in more than half of the patients 2 years after surgery. However, the degree of ossification did not influence the clinical outcome. In paper III the aim was to assess the extent of artifact induced by the arthroplasty device, and how it limits interpretation of the MRI in a 1.5 compared with a 3 Tesla magnet. This study showed that the disc prosthesis induced artifact in both 1.5 and 3 Tesla MRI to such an extent that index level visualization of the root canals was difficult and evaluation of the spinal cord was impossible. MR sequences should accordingly be adjusted in order to produce the least amount of artifacts. In paper IV the aim was to evaluate the relationship between the primary outcome measure neck disability index (NDI) and health-related quality of life (HRQoL) and mental health questionnaires, which showed that there was a significant correlation and that NDI provides a simple and broader understanding of the patients’ overall health situation. The NORCAT study showed excellent clinical outcome for both arthroplasty and fusion, and no significant between-group difference at any scheduled follow-up. There are several aspects that should be considered more thoroughly before fusion is replaced by cervical arthroplasty. The rate of index level reoperations was higher and the duration of surgery longer with arthroplasty, however previous RCTs reported index level reoperations to be higher with fusion. The long-term results from other studies and the 5-year follow-up results from the NORCAT may elucidate this topic. An argument for using arthroplasty instead of and fusion is the preservation of index level motion. There are, however, trials including the NORCAT that have shown a high level of heterotopic ossification in relation to arthroplasty, which emphasizes the need for studies with focus on the underlying reasons of heterotopic ossification development as well as adjacent segment disease. These are aspects that will be assessed at the 5-year NORCAT follow-up, including cost-effectiveness analyses.