Background: Theoretic advantages of cervical disc arthroplasty include preservation of normal motion and biomechanics in the cervical spine, and reduction of adjacent-segment degeneration. The clinical and radiographic effects of cervical disc arthroplasty in short term have been ascertained. The aim of this study is to research the data of mid-term results.
Methods: In this prospective cohort study, 50 patients who underwent cervical disc arthroplasty from December 2003 to January 2006 were enrolled. There were 39 patients who received 1-level disc arthroplasty, and 11 patients received 2-level disc arthroplasty, with an average age of 50.9 years (range from 29 to 73). The median follow-up was 41.85 months (range from 36.00 - 55.63 months). Patients were followed prospectively with respect to their symptoms, neurologic signs, and radiographic results.
Results: The median value of Japanese Orthopaedic Association (JOA) score was 14.0 before surgery, and 16.5 at the most recent follow-up (P < 0.01). The median value of the recovery rate of the JOA score was 92.2%. The preoperative range of motion (ROM) at the indexed level was (10.40 ± 4.97)°, which has significantly correlated with the most recent follow-up ROM which was (8.56 ± 4.76)° (P < 0.05, r = 0.33). The ROM at the operative level at the most recent follow-up was greater than the value at the 3-month follow-up of (7.52 ± 3.37)° (P < 0.05). The preoperative functional spinal unit (FSU) angulation was (-0.96 ± 6.52)°, which was not significantly correlated with that of the most recent follow-up value of (-2.65 ± 7.95)° (P < 0.01, r = 0.53). The preoperative endplate angulation was (2.61 ± 4.85)°, which had no significant correlation with that of the most recent follow-up value of (0.71 ± 6.41)° (P > 0.05).
Conclusions: The clinical and radiographic results of cervical disc arthroplasty are good in mid-term follow-up. The normal range of motion of the operated level and the biomechanics in the cervical spine are well preserved.