Table 3.
Distribution of the implanted levels, 2 years after CDR, in single- and multi-level groups, according to the McAfee Classification for HO
| HO grade | Single-level | Multi-level | p value | ||
|---|---|---|---|---|---|
| % of levels (n) | Mean ROM (p value) | % of levels (n) | Mean ROM (p value) | ||
| Grade 0 | 33.3% (55/165) | 12.32 | 45.0% (50/111) | 10.06 | 0.0233 |
| Grade I | 17.6% (29/165) | 11.38 (0.483) | 20.7% (23/111) | 9.03 (0.4297) | |
| Grade II | 37.0% (61/165) | 8.97 (0.0045) | 21.6% (24/111) | 6.28 (0.0021) | |
| Grade III | 1.8% (3/165) | 1.85 (ND) | 5.4% (6/111) | 2.28 (0.0011) | |
| Grade IV | 10.3% (17/165) | 0.80 (<0.0001) | 7.2% (8/111) | 0.85 (<0.0001) | |
Results are expressed as % of levels (number) for each grade. Comparison between the 2 groups regarding distribution of the 5 grades was performed using a Fisher’s exact test. For each grade of HO, mean ROM was calculated at the index level, 2 years post-operatively. The mean motion of each HO grade was compared to motion of the grade 0, using a Mann–Whitney test, and p value was indicated for each comparison.