Impact of over distraction on occurrence of axial symptom after anterior cervical discectomy and fusion

Abstract

Objective: A retrospective review was undertaken to evaluate the impact of over distraction on cervical axial symptoms (AS) after anterior cervical discectomy and fusion (ACDF).

Methods: The retrospective review included 421 patients who underwent ACDF for one or two segments. Of these, 78 patients for whom complete follow-up data were available were selected for inclusion in the analysis. X-rays of the cervical vertebra were performed immediately after the surgery, 3 months postsurgery, and at a final follow up (6-24 months). According to the presence/absence of AS, the patients were divided into a symptom group (Group S) and a nonsymptom group (Group N). The ratio of intervertebral height change, change in the overall cervical curvature, change in the local curvature of the surgical segment, cervical total range of motion (ROM), and Japanese Orthopaedic Association (JOA) recovery rate were compared and analyzed. A linear regression analysis of the ratio of intervertebral height change and the symptom and severity of the AS according to the Visual Analogue Scale (VAS) was carried out.

Results: The total incidence of AS was 33.97%. C5 nerve root palsy occurred in one case in Group S after the surgery. The neurologic symptoms of both groups were significantly alleviated after the surgery. The ratio of intervertebral height change in Group S was significantly higher than that in Group N at the last follow-up (P < 0.05). However, the changes in the overall cervical curvature, local curvature of the surgical segment, cervical ROM, and JOA recovery rates were not statistically significant (P > 0.05). In Group S, 37% of the patients had symptoms that occurred in the chest area, and the ratio of intervertebral height change was significantly positively correlated with the VAS score of the AS (r = 0.893).

Conclusions: The occurrence of postoperative AS will significantly increase if the ratio of intervertebral height change of the surgical segment after ACDF is over 10%.

Keywords: Cervical spondylosis; anterior cervical fusion; axial symptoms; height of intervertebral space; physiological curvature.

Figure 1

Δh = (H1’+H2’)/2-(H1+H2)/2.

Figure 2

Measurement of C2-C7 angle (β) = (H3+H4)/2.

Figure 3

Measurement of C2~C7 Cobb angle (α), local Cobb angle of surgical segment (γ).

Figure 4

Local curvature change composition comparison between patients in group S and group N.

Figure 5

Sites in forebreast with axial symptoms: 1, 2 collarbone head on both sides, the first and second chest and rib joint of both sides of 3, 4.

Figure 6

Intervertebral height change ratio was significantly positively related to axial symptom VAS score.

Figure 7

Group S, 46 y, female, “bad” in post-operative AS assessment, cervical lateral position X ray. A: Preoperative intervertebral height: 3.19 cm, average intervertebral height of adjacent segment: 0.73 cm; B: Post-operative intervertebral height: 3.68 cm, intervertebral height change ratio before and after surgery was 67.12%.

Figure 8

Group S, 46 y, female, “bad” in post-operative AS assessment, cervical lateral position X ray. A: Post-operative cervical lateral curvature: 11.0°; B: Post-operative cervical lateral curvature: 11.3°.

Figure 9

Group S, 50 y, female, “bad” in post-operative assessment, cervical lateral position X ray. A: Preoperative local cervical lateral curvature: 20.7°; B: Post-operative local cervical lateral curvature: 5.1°.

Figure 10

Group S, 54 y, male, “bad” in post-operative AS assessment, dynamic cervical spine X-ray. A: Preoperative flexion position Angle is 16.7°; B: Preoperative hyperextension angle is 30.1°; C: Post-operative flexion position angle is 13.7°; D: Post-operative hyperextension angle is 29.7°. Cervical range of motion: 46.8° and 43.4°.