Long-term results of the NECK trial—implanting a disc prosthesis after cervical anterior discectomy cannot prevent adjacent segment disease

The Spine Journal 23 (2023) 350−360

Motion preserving anterior cervical disc arthroplasty (ACDA) in patients with cervical radiculopathy was introduced to prevent symptomatic adjacent segment disease as compared to anterior cervical discectomy and fusion (ACDF).

PURPOSE: To evaluate the long-term outcome in patients with cervical radiculopathy due to a herniated disc undergoing ACDA, ACDF or ACD (no cage, no plate) in terms of clinical outcome measured by the Neck Disability Index (NDI). Likewise, clinically relevant adjacent segment disease is assessed as a long-term result.

STUDY DESIGN: Double-blinded randomized controlled trial.

PATIENT SAMPLE: A total of 109 patients with one level herniated disc were randomized to one of the following treatments: ACDA, ACDF with intervertebral cage, ACD without cage.

OUTCOME MEASURES: Clinical outcome was measured by patients’ self-reported NDI, Visual Analogue Scale (VAS) neck pain, VAS arm pain, SF36, EQ-5D, perceived recovery and reoperation rate. Radiological outcome was assessed by radiographic cervical curvature and adjacent segment degeneration (ASD) parameters at baseline and up until five years after surgery.

METHODS: To account for the correlation between repeated measurements of the same individual Generalized Estimated Equations (GEE) were used to calculate treatment effects, expressed in difference in marginal mean values for NDI per treatment group.

RESULTS: Clinical outcome parameters were comparable in the ACDA and ACDF group, but significantly worse in the ACD group, though not reaching clinical relevance. Annual reoperation rate was 3.6% in the first two years after surgery, declined to 1.9% in the years thereafter. The number of reoperations for ASD was not lower in the ACDA group, while the number of reoperations at the index level was higher after ACD, when compared to ACDF and ACDA.

CONCLUSIONS: A persisting absence of clinical superiority was demonstrated for the cervical disc prosthesis five years after surgery. Specifically, clinically relevant adjacent level disease was not prevented by implanting a prosthesis. Single level ACD without implanting an intervertebral device provided worse clinical outcome, which was hypothesized to be caused by delayed fusion. This stresses the need for focusing on timely fusion in future research.

Effectiveness of anterior cervical discectomy with or without interbody fusion and arthroplasty in the treatment of cervical disc herniation; a double-blinded randomised controlled trial

The Spine J Volume 19, Issue 6, Pages 965–975. 2019

Motion preserving anterior cervical disc arthroplasty (ACDA) in patients with cervical radiculopathy was introduced to prevent symptomatic adjacent disc degeneration as compared to anterior cervical discectomy and fusion (ACDF). Prior reports suggest that ACDF is not more effective than anterior cervical discectomy (ACD) alone for the treatment of cervical radiculopathy.

Purpose: To evaluate whether patients with cervical radiculopathy due to a herniated disc benefit more from undergoing ACDA, ACDF, or ACD in terms of clinical outcome measured by the Neck Disability Index (NDI).

Study design: Double-blinded randomized controlled trial

Methods: One hundred-nine patients with one level herniated disc were randomized to one of the following treatments: ACDA, ACDF with intervertebral cage, ACD without fusion. Clinical and radiological outcome was measured by NDI, Visual Analogue Scale (VAS) neck pain, VAS arm pain, SF36, EQ-5D, patients’ self-reported perceived recovery, radiographic cervical curvature, and adjacent segment degeneration (ASD) parameters at baseline and until two years after surgery. BBraun Medical paid €298.837 to cover the costs for research nurses.

Results: The NDI declined from 41 to 47 points at baseline to 19±15 in the ACD group, 19± 18 in the ACDF group, and 20±22 in the ACDA group after surgery (p=0.929). VAS arm and neck pain declined to half its baseline value and decreased below the critical value of 40 mm. Quality of life, measured by the EQ-5D, increased in all three groups. ASD parameters were comparable in all three groups as well. No statistical differences were demonstrated between the treatment groups.

Conclusions: The hypothesis that ACDA would lead to superior clinical outcome in comparison to ACDF or ACD could not be confirmed during a two-year follow-up time period. Single level ACD without implanting an intervertebral device may be a reasonable alternative to ACDF or ACDA.

Sagittal spinal alignment in patients with lumbar disc herniation

Eur Spine J (2010) 19:435–438. DOI 10.1007/s00586-009-1240-1

A retrospective cross-sectional study was designed to evaluate total sagittal spinal alignment in patients with lumbar disc herniation (LDH) and healthy subjects. Abnormal sagittal spinal alignment could cause persistent low back pain in lumbar disease. Previous studies analyzed sciatic scoliotic list in patients with lumbar disc herniation; but there is little or no information on the relationship between sagittal alignment and subjective findings.

The study subjects were 61 LDH patients and 60 age-matched healthy subjects. Preoperative and 6-month postoperatively lateral whole-spine standing radiographs were assessed for the distance between C7 plumb line and posterior superior corner on the top margin of S1 sagittal vertical axis (SVA), lumbar lordotic angle between the top margin of the first lumbar vertebra and first sacral vertebra (L1S1), pelvic tilting angle (PA), and pelvic morphologic angle (PRS1). Subjective symptoms were evaluated by the Japanese Orthopedic Association (JOA) score for lower back pain (nine points).

The mean SVA value of the LDH group (32.7 ± 46.5 mm, ± SD) was significantly larger than that of the control (2.5 ± 17.1 mm), while L1S1 was smaller (36.7 ± 14.5) and PA was larger (25.1 ± 9.0) in LDH than control group (49.0 ± 10.0 and 18.2 ± 6.0, respectively). At 6 months after surgery, the malalignment recovered to almost the same level as the control group.

SVA correlated with the subjective symptoms measured by the JOA score. Sagittal spinal alignment in LDH exhibits more anterior translation of the C7 plumb line, less lumbar lordosis, and a more vertical sacrum. Measurements of these spinal parameters allowed assessment of the pathophysiology of LDH.

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