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Eur Spine J. 2016 Jul;25(7):2271-8. doi: 10.1007/s00586-016-4549-6. Epub 2016 Apr 9.

Heterotopic ossification and clinical outcome in nonconstrained cervical arthroplasty 2 years after surgery: the Norwegian Cervical Arthroplasty Trial (NORCAT).

Author information

1
Department of Neurosurgery, Oslo University Hospital Rikshospitalet, Postboks 4950, Nydalen, 0424, Oslo, Norway. jsundset@ous-hf.no.
2
Faculty of Medicine, University of Oslo, Oslo, Norway. jsundset@ous-hf.no.
3
Department of Neuroradiology, Oslo University Hospital Rikshospitalet, Oslo, Norway.
4
Department of Neurosurgery, Oslo University Hospital Rikshospitalet, Postboks 4950, Nydalen, 0424, Oslo, Norway.
5
National Advisory Unit of Spinal Disorders, University Hospital of Trondheim (St Olavs Hospital HF), Trondheim, Norway.
6
Department of Neurosurgery, University Hospital of Trondheim (St Olavs Hospital HF), Trondheim, Norway.
7
University of Trondheim, Trondheim, Norway.
8
National Advisory Unit of Spinal Disorders and Department of Orthopaedic Surgery, Clinic of Orthopaedics and Rheumatology, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.
9
Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
10
Department of Biostatistics, Epidemiology and Health Economics, Oslo University Hospital, Oslo, Norway.
11
Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway.
12
Department of Neurology and FORMI, Oslo University Hospital Ullevaal, Oslo, Norway.

Abstract

PURPOSE:

Heterotopic ossification is a phenomenon in cervical arthroplasty. Previous reports have mainly focused on various semiconstrained devices and only a few publications have focused on ossification around devices that are nonconstrained. The purpose of this study was to assess the occurrence of heterotopic ossification around a nonconstrained cervical device and how it affects clinical outcome 2 years after surgery.

METHODS:

Thirty-seven patients were included from a larger cohort of a randomized controlled trial (NORCAT) which compared single-level cervical arthroplasty with fusion. The occurrence of heterotopic ossification was assessed with a CT scan and two neuroradiologists determined its degree. For grading, we used the Mehren/Suchomel classification system (grade 0-4). The patients were divided by level of ossification, low grade (0-2) or high grade (3-4), and clinical outcomes were compared. Self-rated disability for neck and arm pain (Neck Disability Index), health-related quality of life (the Short Form-36 and EuroQol-5D), and pain (the Numeric Rating Scale 11) were used as clinical outcome measures.

RESULTS:

Heterotopic ossification was encountered in all patients 2 years after surgery. Complete fusion (grade 4) was found in 16 % of participants, and high-grade ossification (grade 3-4) occurred in 62 %. The remaining patients were classified as having low-grade ossification (grade 2). There were no differences in the clinical outcomes of patients with low- and high-grade ossification.

CONCLUSION:

High-grade heterotopic ossification and spontaneous fusion 2 years after surgery were seen in a significant number of patients. However, the degree of ossification did not influence the clinical outcome.

KEYWORDS:

Arthroplasty; Cervical; Fusion; Heterotopic ossification; Outcome

PMID:
27061727
DOI:
10.1007/s00586-016-4549-6
[Indexed for MEDLINE]

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