116 - Clinical Risk Factors of Heterotopic Ossification Following Cervical T...

#116 Clinical Risk Factors of Heterotopic Ossification Following Cervical Total Disc Replacement: Five-year Clinical and Radiological Follow-up Results

Oral Posters: Cervical Arthroplasty

Presented by: Z. Feifei

Author(s):

Z. Feifei (1)
S. Yu (1)

(1) Peking University (3) rd Hospital, Orthopaedics, Beijing, China

Abstract

Background: The heterotopic ossification (HO) is one of the typical complications following cervical total disc replacement (CTDR). The aim of this study was to identify the clinical risk factors associated with the occurrence of heterotopic ossification following cervical total disc replacement with a long-term follow-up period.

Methods: Six risk factors were examined from clinical record and radiological data: Pre- and Post-operative range of motion (ROM) of the index level; perioperative use of NSAIDs; the ossification of anterior annular fibrosis; the postoperative alignment of functional spine unit (FSU) and the disc height of the target level. The correlation between these six risk factors and the occurrence of HO was evaluated with multivariate analysis.

Results: Thirty three patients with thirty nine segments at a single center underwent Bryan cervical disc replacement from December, 2003 to September, 2007 were reviewed retrospectively. The mean follow-up period was 60.5 months (57~72 months). All the patients were diagnosed CSM (25 patients) or CSR (8 patients) respectively. Twenty seven patients underwent single-level arthroplasty and six underwent arthroplasty at two levels. The levels of surgery included C3/4 (3 levels), C4/5 (4 levels), C5/6 (27 levels) and C6/7 (5 levels). Fifteen segments in thirty nine segments (38.5%) were found the appearance of HO. Among six risk factors, only the disc height ratio of target level and adjacent level as well as FSU kyphosis presented statistical correlation with HO (P< 0.05). In patients with HO, the mean value of disc height ratio was 0.8.

Conclusions: The loss of disc height preoperatively and kyphosis of FSU during follow-up were two possible risk factors of heterotopic ossification after cervical arthroplasty. Patients with disc height loss exceeding 20% are not indicated for Bryan disc replacement.