LAUSR

OBJECTIVE Although cervical disc arthroplasty (CDA) has reportedly been associated with similarly low incidences of complications to anterior cervical discectomy and fusion (ACDF), the phenomenon of anterior bone loss (ABL) is unique to CDA and has only recently gained notice. This study thus aimed to investigate the incidence of ABL and its correlation with cervical alignment post-operation. METHODS Consecutive patients who received CDA for herniated disc or spondylosis were retrospectively reviewed. The development and extent of ABL was detected by comparison of pre- and post-operative serial images for the relative position of the anterior vertebral body with the CDA devices and graded into three levels: Grade 1 (minor bone loss), Grade 2 (anterior portion of the vertebral body without exposure of the artificial disc), and Grade 3 (anterior portion of the vertebral body with exposure of the device). RESULTS A total of 41 patients were analyzed with a mean follow-up of 24.1 months. Under serial radiological examinations during follow-up, all patients (41/41=100%) had bone loss of various degrees, with Grade 3 ABL the most common (30/41=73.1%). There were eight and three patients who had Grades 2 and 1 ABL, respectively. The changes of the Cobb angle (ΔCobb) trended towards higher Grades of ABL. CONCLUSIONS During the mean follow-up of 2 years, ABL was a common radiological finding. More than half of the patients (26/41, 63.4%) in the series gained cervical lordosis (ΔCobb >0) after CDA. These patients with increased cervical lordosis (ΔCobb >0) after CDA had higher Grades of ABL.