Radiological and clinical outcomes of cervical disc arthroplasty for the elderly: a comparison with young patients

Background: This study aimed to investigate whether cervical disc arthroplasty (CDA) would be equally effective in elderly patients as in the young. The inclusion criteria of published clinical trials for CDA-enrolled patients covered the ages from 18 to 78 years. However, there was a paucity of data addressing the differences of outcomes between older and the younger patients. Methods: A series of consecutive patients who underwent one- or two-level CDA were retrospectively reviewed. Patients at the two extreme ends of the age distribution (>= 65 and <= 40 years) were selected for comparison. Clinical outcome parameters included visual analog scale (VAS) of neck and arm pain, neck disability index (NDI), and Japanese Orthopaedic Association (JOA) scores. Radiographic outcomes included range of motion (ROM) at the indexed level and evaluation of heterotopic ossification (HO) by computed tomography (CT). Complication profiles were also investigated. Results: There were 24 patients in the elderly group (>= 65 years old) and 47 patients in the young group (<= 40 years old) with an overall mean follow-up of 28.0 +/- 21.97 months. The elderly group had more two-level CDA, and thus the mean operative time was longer (239 vs. 179 min, p<0.05) than the young group. Both groups had similarly significant improvement in clinical outcomes at the final follow-up. All the replaced disc segments remained mobile on post-operative lateral flexion and extension radiographs. However, the elderly group had a slight decrease in mean ROM (-0.32 degrees +/- 3.93 degrees) at the index level after CDA when compared to that of pre-operation. In contrast, the young group had an increase in mean ROM (+0.68 degrees +/- 3.60 degrees). The complication profiles were not different, though a trend toward dysphagia was noted in the elderly group (p=0.073). The incidence or severity (grading) of HO was similar between the two groups. Conclusions: During the follow-up of two years, CDA was equally effective for patients over 65 years old and those under 40 years in clinical improvement. Although the elderly group demonstrated a small reduction of mean ROM after CDA, in contrast to the young group which had a small increase, the segmental mobility was well preserved at every indexed level for each group.