Impact of Heterotopic Ossification on Range of Motion Following Cervical Disc Replacement.

Authors

Gregory S Kazarian, Jung K Mok, Mihir Dekhne, Stephane Owusu-Sarpong, Takashi Hirase, Kyle W Morse, Vishaal Nayagam, Toney Lewis, Nicholas Giattino, James Farmer, Russel Huang, Han Jo Kim, Sravisht Iyer, James Dowdell, Todd Albert, Sheeraz Qureshi

Published in

Spine. Aug 27, 2026. Epub Aug 27, 2026.

Abstract

Retrospective cohort study.
To evaluate the impact of heterotopic ossification (HO) severity on segmental and global cervical range of motion (ROM) following cervical disc replacement (CDR).
Heterotopic ossification is the most commonly reported complication following CDR, with rates ranging from 40% to over 70% at mid- to long-term follow-up. While high-grade HO is known to restrict motion, the dose-response relationship between HO severity and ROM across multiple spinal levels remains incompletely characterized.
Patients who underwent single-level CDR with minimum 1-year follow-up and flexion-extension radiographs were identified from a single-institution database. HO was graded per McAfee (Grade 0-4) and patients stratified into Grade 0-2 (non-severe HO), Grade 3 (severe HO), and Grade 4 (severe HO with bridging ankylosis). ROM was measured at the operative disc space and C2-7 levels at final follow-up. Pairwise Mann-Whitney comparisons were Bonferroni-corrected across six planned tests (three disc space, three C2-7). Reported pairwise P values reflect adjustment. Kruskal-Wallis omnibus tests were not adjusted.
A total of 146 patients met inclusion criteria (mean age 45.6±9.0 y, 63.7% male, mean follow-up 2.8±1.9 y). Grade 0-2 HO was present in 88 (60.3%), Grade 3 in 47 (32.2%), and Grade 4 in 11 (7.5%). Disc space ROM differed significantly across groups (Kruskal-Wallis P <0.001): Grade 0-2 mean 9.1°±5.4°, Grade 3 mean 6.2°±4.2° (P=0.009), Grade 4 mean 1.3°±2.0° (P <0.001). C2-7 ROM did not differ significantly across HO groups (Kruskal-Wallis P=0.090), with all pairwise comparisons non-significant.
Higher-grade HO following CDR is associated with stepwise reduction in disc space ROM. Grade 3 HO significantly reduces segmental motion compared to Grade 0-2, and Grade 4 HO leads to near-complete segmental motion loss. Regardless of HO severity, C2-7 ROM is preserved, potentially suggesting transfer of motion to adjacent segments.
4.

PMID:
42704647
Bibliographic data and abstract were imported from PubMed on 08 Sep 2026.

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