The clinical utility of anterior cervical plating for anterior cervical discectomy and fusion (ACDF) procedures remains controversial. This study aims to compare the impact of cervical plating on achievement of minimum clinically important difference (MCID) up to 2 years following ACDF.
Patients undergoing primary, single-level ACDF procedures were grouped based on whether their procedure included application of an anterior cervical plate. Demographics, preoperative spinal diagnoses, operative characteristics, and patient-reported outcome measures (PROMs) were compared between plating groups. Achievement of an MCID was assessed using the following previously established thresholds: 12-item Short Form health survey physical component summary (SF-12 PCS) 8.1, visual analogue scale (VAS) neck 2.6, VAS arm 4.1, Neck Disability Index (NDI) 8.5. Rates of MCID achievement were compared between groups.
The cohort included 192 patients of whom 102 received plating and 90 received no plating. Plating status was significantly associated with Charlson Comorbidity Index and insurance status. Operative duration and estimated blood loss were significantly greater for the plating group. Both groups demonstrated significant improvements at the majority of postoperative timepoints. Significant intergroup differences in PROM improvement were demonstrated for VAS neck and NDI at 6 weeks. Rates of MCID achievement differed significantly between groups for NDI at 6 weeks, and 12 weeks, and SF-12 PCS overall.
Patients improved significantly in terms of pain, disability and physical function, regardless of plating status, and with the exception of early neck pain and disability, these improvements were similar between groups. Patients that underwent plating as part of their ACDF procedure achieved an MCID for physical function at lower rates overall.
Anterior cervical discectomy and fusion (ACDF) is a commonly performed spinal procedure to treat cervical radiculopathy and myelopathy, with approximately 130,000 performed in the United States every year [
Plating has been utilized to strengthen the graft area, provide stability, and help maintain sagittal alignment [
Although the stability added to the area of implantation by anterior plating may be advantageous, its associated complications may raise concerns when considering its use in addition to an interbody cage. With the rise of stand-alone cages that anchor directly into the vertebral bodies, the use of anterior plates has been further called into question. ACDF procedures using a stand-alone cage have demonstrated reduced rates of common postsurgical complications, such as dysphagia and ASD [
The currently available literature provides no clear consensus as to whether a stand-alone cage or a cage-plate combination is preferable, as compelling pros and cons have been presented for each and similar rates of fusion have been reported [
Although the use of PROMs may offer a patient-centered perspective on key clinical symptoms, a simple comparison of their values fails to capture a change which patients perceive as a true clinical difference. More recent use of the minimum clinically important difference (MCID) may provide physicians with better insight into the true difference in postoperative symptoms. Defined as the smallest meaningful difference in scores that a patient perceives as beneficial [
Prior to study commencement, this study was approved by the Institutional Review Board of Rush University Medical Center (ORA #14051301) and written informed consent were obtained from patients. A prospectively maintained surgical database was retrospectively reviewed for ACDF procedures from June 2005 to July 2020. Inclusion criteria were primary, singlelevel ACDF procedures for degenerative pathology. Exclusion criteria were patients without clear identification regarding the use of an anterior interbody plate, patients without preoperative PROM data, and patients undergoing surgery to treat traumatic, infectious, or malignant conditions. All procedures were performed by a single, fellowship-trained spine surgeon at the same academic institution. Anterior plate instrumentation consisted of low-profile titanium devices which were fixed to the anterior spine with 2 screws placed into the cranial and caudal vertebral bodies each. Stand-alone cage devices were composed of polyether ether ketone and were fixed to the superior and inferior endplates via one locking screw each.
Patient demographic information was collected which included age, gender, body mass index (BMI; categorized as nonobese: BMI < 30 kg/m2 and obese: BMI ≥ 30 kg/m2), smoking status, diabetic status, American Society of Anesthesiologists classification (ASA; categorized as ≤ II and > II), Charlson Comorbidity Index score (CCI; categorized as < 1 and ≥ 1), ethnicity, and insurance/payment received. Pre-existing spinal pathologies and operative characteristics were recorded for all patients and included operative duration (from skin incision to skin closure, in minutes), estimated blood loss (EBL; in mL), and postoperative length of stay (in hours). Rates of arthrodesis by the 1-year postoperative timepoint were confirmed using computed tomography (CT) scans of the lumbar spine. Additionally, preoperative and final postoperative lateral radiographs were reviewed and measured to determine global cervical lordosis, segmental lordosis, and cervical sagittal vertical axis (SVA) at the operated level. Rates of revision for clinically significant subsidence were also calculated for all patients. PROMs were administered at preoperative and postoperative (6 weeks, 12 weeks, 6 months, 1 year, 2 years) timepoints and included 12-Item Short Form physical component summary (SF-12 PCS), visual analogue scale (VAS) for neck and arm pain, and Neck Disability Index (NDI).
All statistical tests and calculations were performed using Stata IC 16.1 (StataCorp, College Station, TX, USA). Patients were sorted into 2 groups based on whether they had an anterior plate placed as part of their ACDF procedure. Demographic characteristics, pre-existing spinal pathologies, operative and radiographic variables were compared between groups using chi-square analysis and Student t-test for independent samples for categorical and continuous variables, respectively. Change in PROM scores (ΔPROM) was calculated as the difference of each postoperative score from preoperative baseline. A paired Student t-test compared postoperative to preoperative scores to assess improvement following ACDF. Student t-test for independent samples was used to assess differences in ΔPROM between groups at each timepoint. Achievement of MCID was determined by comparing ΔPROM values to the following previously established thresholds: SF-12 PCS (8.1) [
A total of 192 patients were included, of whom 102 received anterior plating and 90 did not. The cohort’s mean age was 47.4 years, 59.9% were male, and 48.4% were obese. Herniated nucleus pulposus was the most common preoperative spinal pathology. Mean operative duration was 53.2 minutes, mean EBL was 35.9 mL, and mean length of stay was 19.0 hours. CCI (p = 0.012) and insurance/payment collected (p = 0.027) were the only demographic characteristics significantly associated with plating status (
Significant postoperative improvements were demonstrated in both groups for all PROMs at all timepoints (p ≤ 0.030), except SF-12 PCS at 2 years (p = 0.100) for the no plating group and SF-12 PCS, and NDI at 6 weeks (p = 0.358, p = 0.066), VAS arm at 1 year (p = 0.145), and VAS neck, VAS arm, and NDI at 2 years (p = 0.347, p = 0.576, p = 0.058) for the plating group (
Following the introduction of stand-alone interbody cages, the utility of anterior plating for ACDF procedures remains controversial. While satisfactory outcomes have been achieved with both techniques, plating has been associated with increased incidence of dysphagia and ASD, while greater rates of subsidence and less restoration of cervical lordosis have been reported with stand-alone cages [
CCI and insurance status differed significantly between groups. The plating group had a higher proportion of patients with a CCI score of 1 or greater, indicating that more of these patients had some medical comorbidity. Narain et al. [
Prevalence of preoperative spinal pathologies did not significantly vary between groups. Operative duration was significantly longer and EBL was significantly greater for the plating group than the no plating group. Similar operative findings have been reported by previous studies [
While some have suggested that anterior plating may lend additional stability to the operative segment, we were unable to detect a significant difference in fusion rates between the 2 groups. These results are largely in line with previous literature which similarly reports satisfactory rates of arthrodesis regardless of plating status [
Our analysis revealed early (6 weeks) differences between groups in terms of postoperative improvements in VAS neck and NDI, with the plating group demonstrating significantly less improvement in both metrics. One possible explanation for these short-term differences could be related to longer time to recover due to the additional operative trauma of anterior plating, which involves additional instrumentation and may require a larger operative window. However, no significant long-term differences in “raw” improvement scores were observed. While mean change scores in NDI, VAS neck, and SF-12 PCS did demonstrate several points of difference at some longitudinal timepoints, the high degree of variability observed in these scores likely contributed to the nonsignificant intergroup difference observed for these measures. Results of previous studies regarding pain and disability outcomes based on the use of anterior plating have been mixed. Etemadifar et al. [
It should be noted that previous studies have primarily compared mean PROM scores between groups, while we compared the magnitude of change in these scores. Our method may allow for more relevant comparison by better accounting for preoperative PROM scores. Furthermore, while a multitude of previous studies have assessed the association of anterior plating with VAS and NDI, few if any have explored physical function outcomes. Our analysis of PROM values did not demonstrate significant differences between groups in either short- or long-term improvement in the included physical function measure.
While a number of comparisons have been made in terms of “raw” PROM values, the lack of reported data regarding rates of clinically meaningful improvement represents a substantial shortcoming of the available literature regarding the use of anterior plating in ACDF procedures. In line with our findings regarding ΔPROM, plating was associated with lower rates of short-term MCID achievement in NDI. However, the more favorable ΔPROM findings in VAS neck were not similarly borne out in our MCID analysis.
Overall, a greater proportion of patients in the no plating group achieved an MCID in SF-12 PCS. Evidence for mechanical/structural benefits of one technique over the other have been relatively consistent but cite pros and cons for each. Although decreased segmental range of motion is often to be desired following fusion procedures, perhaps the increased neck stiffness reported to be associated with plating [
While our study is the first to assess the impact of anterior plating on MCID achievement, it is subject to several notable limitations. Our assessment relied heavily on data obtained from self-reported questionnaires, which are inherently vulnerable to bias. Since our express purpose was to quantify results in terms of patient perceptions, some such bias was likely unavoidable. Additionally, all ACDF procedures were performed by a single experienced spine surgeon at a single academic institution, which may limit the generalizability of our results. Despite these limitations, the present study utilizes a robust sample size, includes longitudinal follow-up data (through 2 years postoperatively), and is the first to include an analysis of MCID achievement to assess ACDF outcomes based on the use or exclusion of anterior plating.
Patients generally demonstrated favorable outcomes and significant improvements in PROM following ACDF, regardless of whether their procedure included anterior plating. In terms of mean PROM score improvement, only short-term neck pain and disability were less favorable for the plating group. Rates of MCID achievement were likewise generally similar for ACDF procedures involving both techniques, and a majority of patients in both groups met these thresholds for neck pain, arm pain, and disability. Clinically meaningful improvements in early (6 weeks, 12 weeks) disability and overall physical function were more common amongst the cage-only group. While the use of anterior plating has both pros and cons for patients undergoing ACDF, clinically important improvements in disability and physical function may be more likely without the use of a plate.
The authors have nothing to disclose.
This study received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Conceptualization: CL, EC, KS; Data curation: CL, SM, CG, KS; Formal analysis: CL, EC; Methodology: CL, EC; Project administration: CL, SM, CG; Writing - original draft: CL, EC, CJ; Writing - review & editing: CL, EC, CJ, SM, CG, KS.
Patient demographics
Demographic | No plate (n = 90) | Plate (n = 102) | p-value |
---|---|---|---|
Age (yr) | 45.6 ± 8.5 | 48.1 ± 11.5 | 0.312 |
Sex | 0.391 | ||
Female | 39 (43.3) | 38 (37.3) | |
Male | 51 (56.7) | 64 (62.8) | |
Body mass index (kg/m2) | 0.684 | ||
< 30 | 45 (50.0) | 54 (52.9) | |
≥ 30 | 45 (50.0) | 48 (47.1) | |
Smoking status | 0.099 | ||
Nonsmoker | 78 (86.7) | 79 (77.5) | |
Smoker | 12 (13.3) | 23 (22.6) | |
Diabetes | 0.227 | ||
Diabetic | 6 (6.7) | 12 (11.8) | |
Nondiabetic | 84 (93.3) | 90 (88.2) | |
ASA PS classification | 0.508 | ||
≤ II | 66 (73.3) | 79 (77.5) | |
> II | 24 (26.7) | 23 (22.6) | |
CCI score | 0.012 |
||
<1 | 30 (33.3) | 18 (17.7) | |
≥1 | 60 (66.7) | 84 (82.4) | |
Ethnicity | 0.353 | ||
White | 63 (70.0) | 76 (74.5) | |
African-American | 12 (13.3) | 14 (13.7) | |
Hispanic | 7 (7.8) | 7 (6.9) | |
Asian | 1 (1.1) | 3 (2.9) | |
Other | 7 (7.8) | 2 (2.0) | |
Insurance | 0.027 |
||
Medicare/Medicaid | 3 (3.3) | 13 (12.8) | |
Workers’ compensation | 27 (30.0) | 36 (35.3) | |
Private | 60 (66.7) | 53 (52.0) |
Values are presented as mean±standard deviation or number (%).
ASA PS, American Society of Anesthesiologists physical status; CCI, Charlson Comorbidity Index.
p < 0.05, statistically significant differences.
p-values calculated using an unpaired t-test or chi-square test to determine differences between groups.
Perioperative characteristics
Characteristic | No plate (n = 90) | Plate (n = 102) | p-value |
---|---|---|---|
Spinal pathology | |||
Degenerative disc disease | 5 (5.6) | 2 (2.0) | 0.185 |
Central stenosis | 24 (26.7) | 32 (31.4) | 0.474 |
Radiculopathy | 20 (22.2) | 19 (18.6) | 0.537 |
Myelopathy | 2 (2.2) | 1 (1.0) | 0.489 |
Myeloradiculopathy | 67 (74.4) | 76 (74.5) | 0.992 |
Herniated nucleus pulposus | 84 (93.3) | 95 (93.1) | 0.957 |
Operative time (min) | 48.8 ± 11.1 | 57.2 ± 13.4 | < 0.001 |
Estimated blood loss (mL) | 31.1 ± 12.0 | 40.2 ± 21.7 | 0.001 |
Length of stay (hr) | 17.9 ± 15.1 | 20.1 ± 22.0 | 0.431 |
Arthrodesis |
85 (98.8) | 97 (98.0) | 0.645 |
Cervical lordosis (°) | |||
Preoperative | 8.4 ± 6.0 | 9.5 ± 7.2 | 0.385 |
Postoperative | 10.5 ± 6.9 | 10.8 ± 8.8 | 0.828 |
Change | 2.1 ± 6.5 | 1.3 ± 7.3 | 0.547 |
Segmental lordosis (°) | |||
Preoperative | 3.9 ± 2.6 | 4.1 ± 3.9 | 0.704 |
Postoperative | 4.9 ± 3.8 | 6.2 ± 4.5 | 0.083 |
Change | 1.0 ± 5.0 | 2.2 ± 5.5 | 0.227 |
Cervical sagittal vertical axis (mm) | |||
Preoperative | 26.9 ± 9.1 | 28.0 ± 11.1 | 0.605 |
Postoperative | 27.7 ± 9.7 | 28.7 ± 9.4 | 0.568 |
Change | 0.7 ± 6.9 | 0.8 ± 6.7 | 0.978 |
Values are presented as number (%) or mean±standard deviation.
p < 0.05, statistically significant differences.
p-values calculated using an unpaired t-test or chi-square test to determine differences between groups.
Insufficient follow-up data was available to determine fusion status for 7 patients.
PROM improvement following ACDF
No plate |
Plate |
p-value |
||||||
---|---|---|---|---|---|---|---|---|
Mean ± SD | ΔPROM | p-value |
Mean ± SD | ΔPROM | p-value |
|||
SF-12 PCS | ||||||||
Preoperative | 36.1 ± 8.7 | - | - | 39.6 ± 9.8 | - | - | - | |
6 Weeks | 38.2 ± 8.8 | 3.6 ± 8.6 | 0.014 |
38.8 ± 10.6 | 1.3 ± 9.9 | 0.358 | 0.254 | |
12 Weeks | 42.6 ± 8.7 | 5.9 ± 8.1 | < 0.001 |
45.0 ± 10.5 | 4.3 ± 7.7 | < 0.001 |
0.287 | |
6 Months | 42.7 ± 10.1 | 8.5 ± 11.0 | < 0.001 |
41.4 ± 9.4 | 6.4 ± 9.2 | 0.002 |
0.421 | |
1 Year | 43.1 ± 10.9 | 8.2 ± 12.6 | 0.004 |
43.7 ± 10.3 | 4.6 ± 6.4 | 0.004 |
0.255 | |
2 Years | 41.7 ± 19.3 | 6.6 ± 14.4 | 0.100 | 46.0 ± 11.5 | 6.5 ± 8.3 | 0.027 |
0.988 | |
VAS neck | ||||||||
Preoperative | 6.5 ± 2.2 | - | - | 5.9 ± 2.4 | - | - | - | |
6 Weeks | 3.2 ± 2.4 | 3.1 ± 2.3 | < 0.001 |
3.9 ± 2.7 | 1.9 ± 3.1 | < 0.001 |
0.018 |
|
12 Weeks | 3.0 ± 2.5 | 3.4 ± 2.5 | < 0.001 |
3.0 ± 2.5 | 2.9 ± 3.0 | < 0.001 |
0.348 | |
6 Months | 3.0 ± 2.8 | 3.5 ± 2.8 | < 0.001 |
2.6 ± 2.5 | 3.2 ± 3.2 | < 0.001 |
0.687 | |
1 Year | 3.1 ± 2.6 | 2.9 ± 3.0 | < 0.001 |
3.9 ± 3.0 | 1.9 ± 3.6 | 0.025 |
0.258 | |
2 Years | 4.1 ± 2.4 | 2.7 ± 2.3 | 0.001 |
4.8 ± 3.6 | 1.5 ± 4.5 | 0.347 | 0.421 | |
VAS arm | ||||||||
Preoperative | 6.0 ± 2.6 | - | - | 6.2 ± 2.5 | - | - | - | |
6 Weeks | 1.9 ± 2.1 | 3.8 ± 2.8 | < 0.001 |
3.3 ± 2.8 | 2.7 ± 3.5 | < 0.001 |
0.081 | |
12 Weeks | 2.4 ± 2.6 | 3.4 ± 3.0 | < 0.001 |
3.1 ± 3.2 | 3.1 ± 3.8 | < 0.001 |
0.684 | |
6 Months | 2.2 ± 2.6 | 3.4 ± 3.1 | < 0.001 |
3.3 ± 3.2 | 2.8 ± 3.4 | < 0.001 |
0.358 | |
1 Year | 2.8 ± 2.9 | 2.5 ± 3.4 | < 0.001 |
4.7 ± 3.0 | 1.5 ± 4.5 | 0.145 | 0.374 | |
2 Years | 4.0 ± 3.0 | 2.0 ± 2.2 | 0.003 |
3.3 ± 4.1 | 1.2 ± 5.5 | 0.576 | 0.642 | |
NDI | ||||||||
Preoperative | 44.8 ± 19.9 | - | - | 39.1 ± 17.7 | - | - | - | |
6 Weeks | 29.3 ± 18.7 | 13.6 ± 14.7 | < 0.001 |
33.2 ± 21.3 | 5.0 ± 19.0 | 0.066 | 0.010 |
|
12 Weeks | 27.3 ± 20.9 | 17.0 ± 15.0 | < 0.001 |
27.6 ± 20.5 | 12.1 ± 21.6 | < 0.001 |
0.198 | |
6 Months | 22.9 ± 20.9 | 21.6 ± 18.2 | < 0.001 |
24.5 ± 22.6 | 15.7 ± 22.1 | < 0.001 |
0.177 | |
1 Year | 26.2 ± 21.5 | 16.3 ± 19.2 | < 0.001 |
21.7 ± 20.0 | 15.3 ± 22.9 | 0.012 |
0.866 | |
2 Years | 28.7 ± 21.4 | 13.1 ± 14.9 | 0.004 |
21.6 ± 19.2 | 21.6 ± 24.4 | 0.058 | 0.323 |
PROM, patient-reported outcome measure; ACDF, anterior cervical discectomy and fusion; SD, standard deviation; SF-12 PCS, 12-item Short Form health survey physical component summary; VAS, visual analogue scale; NDI, Neck Disability Index.
p < 0.05, statistically significant differences.
p-values calculated using a paired t-test to assess within-group improvement from preoperative baseline.
p-values calculated using a t-test for independent samples to assess intergroup differences in PROM score improvement (ΔPROM).
MCID achievement rates
Variable | No plate | Plate | p-value |
---|---|---|---|
SF-12 PCS | |||
6 Weeks | 13 (33.3) | 13 (25.0) | 0.384 |
12 Weeks | 18 (40.0) | 23 (33.8) | 0.504 |
6 Months | 17 (44.7) | 11 (42.3) | 0.847 |
1 Year | 11 (45.8) | 4 (20.0) | 0.072 |
2 Years | 7 (46.7) | 4 (36.4) | 0.599 |
Overall | 40 (59.7) | 34 (41) | 0.022 |
VAS neck | |||
6 Weeks | 33 (53.2) | 23 (41.1) | 0.187 |
12 Weeks | 40 (67.8) | 27 (52.9) | 0.111 |
6 Months | 31 (58.5) | 29 (61.7) | 0.744 |
1 Year | 14 (41.2) | 9 (42.9) | 0.902 |
2 Years | 5 (33.3) | 4 (44.4) | 0.586 |
Overall | 53 (76.8) | 40 (65.6) | 0.156 |
VAS arm | |||
6 Weeks | 26 (45.6) | 21 (40.4) | 0.582 |
12 Weeks | 21 (41.2) | 20 (40.8) | 0.971 |
6 Months | 19 (38.8) | 19 (44.2) | 0.599 |
1 Year | 9 (26.5) | 6 (30.0) | 0.780 |
2 Years | 3 (20.0) | 2 (28.6) | 0.655 |
Overall | 36 (57.1) | 33 (57.9) | 0.934 |
NDI | |||
6 Weeks | 33 (58.9) | 19 (37.3) | 0.025 |
12 Weeks | 37 (72.6) | 23 (48.9) | 0.017 |
6 Months | 33 (68.8) | 26 (65.0) | 0.709 |
1 Year | 17 (51.5) | 10 (55.6) | 0.782 |
2 Years | 9 (60.0) | 4 (57.1) | 0.899 |
Overall | 51 (82.3) | 36 (66.7) | 0.053 |
Values are presented as number (%).
MCID, minimum clinically important difference; SF-12 PCS, 12-item Short Form health survey physical component summary; VAS, visual analogue scale; NDI, Neck Disability Index.
p < 0.05, statistically significant differences.
p-values calculated using a chi-square test to assess MCID achievement between groups.