Table 1 Patient demographics.

Male: Female (cases)

194: 71

Age at surgery (years old)

63.3 ± 11.7

Disease duration (months)

43.1 ± 59.7

Body mass index

25.7 ± 4.2

Diabetes (no. of cases)

87/265

JOA score (pts.)

 Pre-op

10.4 ± 3.1

 Post-op. 1y

13.6 ± 2.6

 Post-op. 2y

13.4 ± 2.9

  Acquired points

3.0 ± 2.7

  Recovery rate (%)

44.9 ± 35.5

Pre-op. neck pain (VAS, mm)

62.0 ± 21.4

Surgical procedures (cases)

 Laminoplasty

145

 Posterior decompression & fusion

64

 Anterior decompression & fusion

56

Imaging findings

 Type of OPLL (cases)

  Continuous

30

  Segmental

99

  Mixed

115

  Localized

21

 Canal narrowing rate (%)

43.5 ± 15.6

 C2-7 angle (°)

9.3 ± 11.9 (ΔC2-7 angle: − 1.7 ± 9.9)

 range of motion (°)

26.9 ± 14.0 (ΔROM: − 9.6 ± 15.1)

 T2 high signal change (cases)

231/265