A total of 379 CSM patients, including 259(68.34%) male and 120(31.66%) female, had undergone surgical intervention of AcA. No patient died at our last follow-ups. The average age was 56.25 ± 10.13 (range 22–84, 56). 71 (18.73%) patients had histories of cervical injury. And 87 (22.96%) patients were diagnosed with confirmed OPLL. The average preoperative JOA and VAS Scores were 11.04 ± 2.23 (0–14, 11) and 1.66 ± 1.49 (0–6, 2) respectively.
According to our data, 133(35.09%) patients had AcA. The rest 246(64.91%) had AcAsa. There were no statistical differences on the preoperative factors between the two groups. The corpectomy level was among C3-C7 and the discectomy level was at the nearest intervertebral space above or below. The count of the cage-above-mesh type was 223 (58.84%) and the cage-below-mesh type was 156(41.16%) (Fig. 1). The average surgery time was 135.73 ± 33.34 (75–318, 130) minutes and the average blood loss was 117.45 ± 106.06 (30-1000, 100) ml. 4(1.06%) patients had intraoperative blood transfusion. 13(3.43%) patients had CSF leakage. And 3(0.79%) patients had suffered from acute postoperative hematoma, which then been dealt with emergency second time surgeries.
All patients had experienced smooth recoveries. Compression bandages around the neck were applied to patients with CSF leakage. All the leakages stopped within the first week. 24(6.33%) patients complained about dysphagia after surgeries. No other severe complications took place after surgeries. The average hospital stay time was 7.19 ± 1.66 (2–19, 7) day. 28 (15 AcA /13 AcAsa) patients’ radiographic follow-ups were lost. Detailed patients’ information is listed in Table 1.
Table 1
Demographics and clinical characteristics of the patients included in the series.
Time | JOA Score | p | RIS (%) | VAS Score | p |
1 day | 12.57 ± 1.87 | < 0.001 | 21.63 ± 24.35 | 1.03 ± 1.14 | < 0.001 |
6 months | 13.10 ± 1.71 | < 0.001 | 30.14 ± 24.31 | 0.69 ± 0.86 | < 0.001 |
12 months | 13.58 ± 1.69 | < 0.001 | 39.68 ± 24.17 | 0.56 ± 0.80 | < 0.001 |
Surgical Feasibility Of AcAsa
The average JOA Scores of the AcAsa group 1 day, 6 months and 12months postoperatively were 12.57 ± 1.87 (6–16, 13), 13.10 ± 1.71 (8–16, 14) and 13.58 ± 1.69 (8–16, 14). The corresponding improvement rates of JOA Score (RIS) were 21.63%±24.35% (-66.67%-75%, 25.00%), 30.14%±24.31% (-66.67%-75%, 33.33%) and 39.68 ± 24.17 (-33.33%-83.33%, 42.86%). And the average VAS Scores 1 day, 6 months and 12months postoperatively were 1.03 ± 1.14 (0–5, 1), 0.69 ± 0.86 (0–4, 0) and 0.56 ± 0.80 (0–4, 0). At each mentioned time point, the postoperative JOA and VAS Scores were significantly higher than the preoperative ones (Table 2).
Table 2
Post-operative JOA scores in AcAsa group and statistical comparisons with pre-operative JOA score.
Factors | RIS after Surgery (%) |
1 day | p | 6 months | p | 12 months | p |
Gender (M/F) | 21.05 ± 27.64 /20.49 ± 24.43 | 0.879 | 31.30 ± 22.99 /29.68 ± 22.99 | 0.615 | 39.18 ± 24.76 /40.86 ± 22.82 | 0.620 |
Age (≥ 56/<56) | 22.08 ± 24.43 /19.65 ± 28.88 | 0.476 | 29.53 ± 23.49 /32.15 ± 22.41 | 0.373 | 39.35 ± 22.79 /40.01 ± 25.60 | 0.831 |
Symptom Duration (≤ 12months/>12months) | 23.81 ± 22.93 /18.81 ± 26.11 | 0.112 | 32.91 ± 21.18 /27.96 ± 25.01 | 0.095 | 41.82 ± 23.38 /36.75 ± 25.02 | 0.105 |
Cage Location (above/below) | 22.88 ± 24.87 /18.21 ± 28.85 | 0.175 | 30.25 ± 23.76 /31.58 ± 21.91 | 0.656 | 39.01 ± 24.54 /40.57 ± 23.75 | 0.617 |
Trauma (yes/no) | 18.00 ± 19.36 /21.35 ± 27.68 | 0.498 | 29.27 ± 17.82 /31.07 ± 23.70 | 0.672 | 40.30 ± 19.95 /39.58 ± 24.82 | 0.873 |
OPLL (yes/no) | 14.86 ± 21.54 /21.82 ± 27.32 | 0.164 | 29.09 ± 22.38 /31.09 ± 23.08 | 0.644 | 36.99 ± 24.83 /40.09 ± 24.10 | 0.494 |
Preoperative JOA Score (≥ 12/<12) | 22.60 ± 27.69 /19.57 ± 24.11 | 0.359 | 29.73 ± 24.49 /31.82 ± 21.49 | 0.477 | 40.69 ± 25.91 /38.74 ± 22.50 | 0.529 |
Preoperative VAS Score (≥ 2/<2) | 18.17 ± 24.87 /24.85 ± 23.63 | 0.032 | 26.64 ± 23.06 /34.55 ± 22.29 | 0.007 | 34.71 ± 24.29 /44.11 ± 23.27 | 0.002 |
We analyzed the postoperative RIS between several sub-groups from the AcAsa group to determine whether any certain kinds of patients may benefit more from AcAsa. The sub-groups divided by gender, age, symptom duration, cage-mesh relative position, trauma history, OPLL and preoperative JOA Score showed no statistical differences in the postoperative RIS at the time points of 1 day, 6 months, and 12 months. However, at each time point, patients with preoperative VAS Score < 2 had more favorable outcomes then patients whose preoperative VAS Score ≥ 2 (p = 0.032/0.007/0.002) (Table 3).
Table 3
Post-operative improvement rates of JOA score in different sub-groups of the AcAsa group.
Factors | N(AcAsa / AcA) | p |
Operative Duration | - | 0.400 |
Blood Loss | - | 0.011 |
Blood Transfusion | 2/2 | 0.530 |
CSF Leakage | 6/7 | 0.086 |
Acute Hematoma & Reoperation | 2/1 | 0.949 |
Length of Hospital Stay | - | 0.782 |
Dysphagia | 11/13 | 0.038 |
12months Postoperative Cage Shift ≥ 3 mm | 4/6 | 0.092 |
12months Postoperative ASD | 11/7 | 0.617 |
Surgical Safety Of AcAsa
To compare the surgical safety outcomes between AcAsa and conventional AcA, we analyzed the factors of operative duration, blood loss, intraoperative blood transfusion and the length of hospital stay. We also compared the incidence of acute postoperative complications like CSF leakage, acute hematoma and postoperative dysphagia. Long-term complications, including the incidence of cage shift, cervical instable, delayed fusion at the ACDF level and ASD at 12 months postoperatively were compared as well. Our results showed that patients who had AcAsa had a smaller amount of blood loss than AcA (P = 0.011). Moreover, the incidence of postoperative dysphagia is significantly lower in the AcAsa group (p = 0.038). No postoperative cervical instable or delayed fusion on the ACDF level was found on all patients at our final follow-ups. On our one year follow-ups, 6 (5.08%) patients in the AcA group and 4 (1.72%) patients in the AcAsa group had severe cage shift (≥ 3 mm). 7 (5.93%) patients in the AcA group and 11 (4.72%) patients in the AcAsa group had developed confirmed ASD before the last followed-ups. No statistical differences were found on the incidence of these complications (Table 4).
Table 4
Comparisons of surgical safety factors and complications between AcAsa and AcA group.
Factors (AcAsa / AcA) | Pre-surgery | p | Time after Surgery |
1 day | p | 6 months | p | 12 months | p |
RIS (%) | - | - | 21.63 ± 24.35 /18.10 ± 22.78 | 0.170 | 30.14 ± 24.31 /29.36 ± 18.46 | 0.747 | 39.68 ± 24.17 /38.32 ± 21.14 | 0.585 |
VAS Score Reduction | - | - | 0.71 ± 0.82 /0.53 ± 0.83 | 0.038 | 0.87 ± 0.98 /1.02 ± 0.95 | 0.143 | 1.00 ± 1.09 /1.15 ± 1.03 | 0.193 |
Cervical Motion (°) | 8.36 ± 4.18 /9.26 ± 4.53 | 0.064 | - | - | 3.97 ± 3.06 /3.57 ± 2.52 | 0.222 | 2.19 ± 2.23 /2.25 ± 1.56 | 0.784 |
Disc Space Height (mm) | 11.74 ± 2.26 /11.59 ± 2.29 | 0.531 | 11.37 ± 2.29 /11.33 ± 2.24 | 0.860 | 11.44 ± 2.30 /11.51 ± 2.42 | 0.802 | 11.64 ± 2.26 /11.43 ± 2.24 | 0.407 |
Symptom Recurrence | - | - | - | - | 10/9 | 0.324 | 18/15 | 0.251 |
Surgical Effectiveness Of AcAsa
Finally, we compared the surgical effectiveness and outcomes between AcAsa and AcA. No differences were shown on the RIS at 1 day, 6months and 12months postoperative. The comparing in between VAS Scores showed that the improvement of VAS Score was significantly higher in the AcAsa group 1 day after surgeries, but revealed no differences at 6months and 12mongths follow-ups. Patients’ disc space height and cervical motion of the ACDF levels at the 6months and 12months postoperative showed no differences between the two groups. In the end, during our follow-ups, 10 (4.07%) patients in the AcAsa group and 9 (6.77%) in the AcA group complained about the recurrence of symptom within the first 6 months, and the number of symptom recurrence raised to 18 (7.32%) and 15 (11.28%) respectively at 12 months follow-up. Chi-square test and survival curves for the symptom recurrence free survival (SRFS) rate both showed no statistical differences in the two groups (Table 5 & Fig.
2).