Heterotopic Ossification after Cervical Arthroplasty with ProDisc-C: Time Course Radiographic Follow-up over 3 years.
OBJECTIVE
Heterotopic ossification (HO) is a well-known complication after total hip replacement. But the occurrence rate by the time-course, clinical effect and risk factors of HO after total cervical disc replacement (TCDR) are not well described. The purpose of this study is to evaluate the occurrence rate by the time-course and risk factors for HO after TCDR with a ProDisc-C.


METHODS
Thirty-two patients whom followed up more than one year after the TCDR are enrolled. Radiographic study was done at 12, 24 and 36 months after the TCDR and classified HO with McAfee classification. Segmental range of motion, preoperative existence of spondylosis, type of operation, disc space occupying ratio by artificial disc, surgical level are analyzed to identify the risk factors of HO. The visual analog scale and the neck disability index were evaluated preoperatively and at last follow-up time for clinical parameters.


RESULTS
Eighteen patients (56%) showed HO at 12 months, 18 patients (86%) showed HO at 24 months and 6 patients (89%) showed HO at 36 months after the TCDR. Clinical significant HO(Grade 3 and 4) was shown in one patient (3%) at 12 months, 3 patients (14%) at 24 months and 5 patients (56%) at 36 months. Only post-operative follow-up period increases the risk of development clinical significant HO. All patients showed improvement of clinical parameters (p<0.005).


CONCLUSIONS
Incidence of HO is getting higher as time course progress. However, there are no relation between clinical outcome and radiologic change of ROM and the grade of HO.
Department of Neurosurgery, Dong-A University College of Medicine, Busan, Korea.
Yong-Hwan
YH
Cho
Department of Neurosurgery, Spine and Spinal Cord Institute, Gangnam Severance Spine Hospital, Yonsei University College of Medicine, Seoul, Korea.
Keun-Su
KS
Kim
Department of Neurosurgery, Dong-A University College of Medicine, Busan, Korea.
Young-Min
YM
Kwon
Cervical arthroplasty; Heterotopic ossification; Total disc replacement