PEEK Cages versus PMMA Spacers in Anterior Cervical Discectomy: Comparison of Fusion, Subsidence, Sagittal Alignment, and Clinical Outcome with a Minimum 1-Year Follow-Up

Table 5

Comparison of fusion and sagittal alignment according to subsidence.

PEEK cage (𝑛=45)

PMMA Sulcem (𝑛=42)

PMMA Palacos (𝑛=33)

Overall (𝑛=120)

𝑛 (levels)

Fused levels

Change in SSA^†

𝑛 (levels)

Fused levels

Change in SSA^†

𝑛 (levels)

Fused levels

Change in SSA^†

𝑛 (levels)

Fused levels

Change in SSA^†

Subsidence ≥ 3 mm

16

12/15

−5.5° (r, −15.1–3.5)

15

11/15

−2.0° (r, −15.6–16.4)

12

7/12

0.3° (r, −5.7–15.9)

43

30/42

−2.6° (r, −15.6–16.4)

Subsidence < 3 mm

29

17/28

−3.4° (r, −16.1–2.9)

27

15/27

−2.6° (r, −10.6–11.2)

21

8/21

−1.7° (r, −6.3–7.9)

77

40/76

−2.6° (r, −16.1–11.2)

𝑃

0.308^∧

0.124^#

0.330^∧

0.800^#

0.300^∧

0.297^#

0.053^∧

1.00^#

The table shows ratios of fused levels and change in segmental sagittal alignment according to the degree of subsidence with a threshold of 3 mm.
^#Student's 𝑡-test (two-tailed).
^∧Fisher exact test (two-tailed).
^†Negative toward kyphosis; r: range.