Difference in occurrence of heterotopic ossification according to prosthesis type in the cervical artificial disc replacement.
METHODS
Retrospective study of the difference of heterotopic ossification (HO) occurrence according to 3 different types of prosthesis.


OBJECTIVE
This study was designed to investigate the difference of HO occurrence according to different type of prosthesis.


BACKGROUND
HO is defined as formation of the bone outside the skeletal system. Reported HO occurrence rate in cervical artificial disc replacement (ADR) was unexpectedly high and varied. But the influencing factors of HO in cervical ADR have not been elucidated well. The prosthesis-related factors for making difference of HO occurrence were investigated in this study.


METHODS
A total of 170 patients undergoing cervical arthroplasty with the Bryan cervical disc prosthesis (Medtroic Sofamor Danek, Memphis, TN), Mobi-C disc prosthesis (LDR Medical, Troyes, France), and ProDisc-C (Synthes, Inc., West Chester, PA) were included. Cervical lateral radiographs obtained before and after surgery were used to identify HO. Occurrence rate, occurrence-free period, location, and grade of HOs were investigated according to the different prosthesis.


RESULTS
Each prosthesis group included patients as follows: Bryan disc, 81 patients; Mobi-C, 61 patients; and ProDisc-C, 28 patients. Overall HO rate was 40.6% (69 of 170 patients). Each HO occurrence rate by prosthesis was as follows: the Bryan disc group, 21.0%; Mobi-C group, 52.5%; and the ProDisc-C group, 71.4%. In the survival analysis, all patients showed 27.1 +/- 3.7 months as the median survival. The Bryan disc group showed statistically longer survival (48.4 +/- 7.4 months) than the other groups.


CONCLUSIONS
Occurrence of HO is an inevitable postoperative complication after cervical ADR. The occurrence rate of HO was higher than our expectation. Moreover, definite differences in occurrence rate according to the prosthesis type were identified by this study.
Yi
Seong
S
Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University, College of Medicine, Seoul, Korea.
Kim
Keung Nyun
KN
Yang
Moon Sul
MS
Yang
Joong Won
JW
Kim
Hoon
H
Ha
Yoon
Y
Yoon
Do Heum
DH
Shin
Hyun Chul
HC
D000293:Adolescent; D000328:Adult; D000368:Aged; D001178:Arthroplasty / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D019643:Arthroplasty, Replacement / Q000009:adverse effects* / Q000379:methods; D002574:Cervical Vertebrae / Q000601:surgery*; D017586:Diskectomy / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D019544:Equipment Failure Analysis / Q000379:methods; D005260:Female; D006801:Humans; D015994:Incidence; D007595:Joint Prosthesis / Q000009:adverse effects* / Q000145:classification*; D008297:Male; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D011183:Postoperative Complications / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D011474:Prosthesis Design / Q000009:adverse effects; D012189:Retrospective Studies; D055815:Young Adult