Clinical impact and imaging results after a modified procedure of ACDF: a prospective case-controlled study based on ninety cases with two-year follow-up

Abstract

Study design: This is a prospective case-controlled study.

Background: To analyze the postoperative axial pain and cage subsidence of patients presenting with cervical spondylotic myelopathy (CSM) after a modified procedure of ACDF (mACDF).

Methods: Ninety patients with CSM were prospectively collected from 2014 to 2018. The patients were divided into spread group and non-spread group (48:42 ratio) according to the cage placement with or without releasing the Caspar cervical retractor after decompression. Spread group received conventional ACDF and non-spread group received mACDF. Patients were followed-up for at least 24 months after surgery. Radiologic data, including height of intervertebral space and Cobb Angle, were collected. Nervous system function was obtained using JOA scores, and level of pain was assessed using VAS scores.

Results: A total of 90 patients were enrolled and the patients were divided into spread group (n = 48) and none-spread group(n = 42). Cage subsidence of (spread group vs none-spread group) was (0.82 ± 0.68 vs 0.58 ± 0.81) mm, (0.64 ± 0.77 vs 0.34 ± 0.46) mm, (0.48 ± 0.43 vs 0.25 ± 0.28) mm, and (0.45 ± 0.47 vs 0.17 ± 0.32) mm at 3 months, 6 months, 12 months and 24 months, respectively. The period exhibiting the most decrease of the height of intervertebral space was 3 months postoperatively. However, there was no statistical difference in the height of intervertebral space, JOA or VAS scores at the final follow-up between the two groups.

Conclusions: The mACDF can avoid excessive distraction by releasing the Caspar Cervical retractor, restore the "natural height" of cervical vertebra, relieve immediate pain after surgery, and prevent rapid Cage subsidence and the loss of cervical curvature.

Keywords: Axial pain; Cage subsidence; Cervical spondylotic myelopathy; Modified ACDF; Natural height.

Fig. 1.

The height of intervertebral height (disk height) pre-operatively, at 1 week, and at 3, 6,12,24 months post-operatively in spread group

Fig. 2.

The height of intervertebral height (disk height) pre-operatively, at 1 week, and at 3, 6,12,24 months post-operatively in none-spread group

Fig 3.

Cage subsidence at 3,6,12,24 months post-operatively between spread group and none-spread group. There was a significant difference in cage subsidence at 6),12,24 months post-operatively between the two groups (p<0.05)

Fig 4.

C2–C7 Cobb angle pre-operatively, at 1 week, and at 24 month post-operatively in spread group. There was a significant difference between preoperative and postoperative Cobb angle (p<0.01)

Fig. 5.

C2–C7 Cobb angle pre-operatively, at 1 week, and at 24 month post-operatively in none-spread group. There was a significant difference between preoperative and postoperative Cobb angle (p<0.01)

Fig. 6.

Japanese Orthopedic Association Score (JOA) pre-operatively, at 1 week, and at 3, 6,12,24 months post-operatively between spread group and none-spread group. The JOA score in spread group one week after surgery was higher than that in none-spread group (p<0.05). No significant difference was observed subsidence between the two groups at 3, 6,12,24 months post-operatively (p>0.05)

Fig. 7.

Visual analogue scale (VAS) pre-operatively, at 3, 6,12,24 months post-operatively between spread group and none-spread group. The VAS score in spread group one week after surgery was higher than that in none-spread group (p<0.05). No significant difference was observed subsidence between the two groups at 3, 6,12,24 months post-operatively (p<0.05)

Fig. 8.

A. The absolute value of the anteroposterior diameter of the upper vertebral body of the diseased segment L and the upper edge of the upper vertebral body to the lower edge of the lower vertebral body. Absolute distance H; B. Actual measured value l and h after operation

Fig. 9

Typical case: The 60-year-old male patient was hospitalized for 2 months due to numbness in both upper limbs and unstable walking. C4/5 intervertebral disc prolapsed (Fig. 9A), and the fusion cage was implanted in the expanded state. At the last follow-up, the intervertebral disc height decreased and the cervical spine curvature became straight (Fig. 9C)