Single-center retrospective study.
This study aims to evaluate the surgical invasiveness of single-segment posterior lumbar interbody fusion (PLIF) by comparing perioperative blood loss in PLIF with traditional pedicle screws (PS), cortical bone trajectory screws (CBT), and percutaneous pedicle screws (PPS).
Intraoperative blood loss has often been used to evaluate surgical invasiveness. However, in patients undergoing spinal surgery, more blood loss is observed postoperatively than intraoperatively. Therefore, evaluating surgical invasiveness using only the intraoperative bleeding volume may result in considerable underestimation of the actual surgical invasiveness.
This study included patients who underwent single-segment PLIF between January 2012 and December 2017. In total, seven patients underwent PLIF with PS (PS-PLIF), nine underwent PLIF with CBT (CBT-PLIF), and 15 underwent PLIF with PPS (PPS-PLIF).
No significant differences were noted in terms of operation time or intraoperative bleeding between the PS-PLIF, CBT-PLIF, and PPS-PLIF groups. However, the postoperative drainage volume in the PPS-PLIF group (210.1 mL; range, 50–367 mL) was determined to be significantly lower than that in the PS-PLIF (416.7 mL; range, 260–760 mL; p=0.002) and CBT-PLIF (421.1 mL; range, 180–890 mL; p=0.006) groups. In addition, the total amount of intraoperative bleeding and postoperative drainage was found to be significantly lower in the PPS-PLIF group (362.8 mL; range, 145–637 mL) than in the PS-PLIF (639.6 mL; range, 285–1,000 mL; p=0.01) and CBT-PLIF (606.7 mL; range, 270–950 mL; p=0.005) groups.
Based on our findings, evaluating surgical invasiveness using only intraoperative bleeding can result in the underestimation of actual surgical invasiveness. Even with single-segment PLIF, the amount of perioperative bleeding can vary depending on the way the posterior instrument is installed.
Posterior lumbar interbody fusion (PLIF) or transforaminal lumbar interbody fusion has been considered as the standard surgical procedure for neurological symptoms associated with lumbar degenerative spondylolisthesis and disc degeneration. In recent years, lumbar spinal fusion surgery with less invasion to the paraspinal muscles has been developed in an attempt to reduce postoperative pain and facilitate earlier recovery after surgery. Foley et al. [
Surgery time and intraoperative blood loss are often used in determining surgical invasiveness [
This retrospective study was performed in a single facility. The data were collected from the patients’ electronic medical records and were evaluated retrospectively. In total, 91 patients were found to have undergone single-segment PLIF, including decompression of adjacent segments, between January 2012 and December 2017. Of these 91 patients, eight underwent PS-PLIF, 12 underwent CBT-PLIF, and 57 underwent PPS-PLIF. Of the 77 patients who underwent these procedures, we excluded three patients who underwent CBT-PLIF and 19 patients who underwent PPS-PLIF because of their undergoing dialysis. We also excluded non-dialysis patients who underwent revision surgery (one patient in the PS-PLIF group and 23 in the PPS-PLIF group). Therefore, this present study included seven patients who underwent PS-PLIF, nine patients who underwent CBT-PLIF, and 15 patients who underwent PPS-PLIF. All patients have reportedly undergone surgery for neurological symptoms associated with lumbar degenerative spondylolisthesis and disc degeneration.
The requirement for informed consent from individual patients was omitted because of the retrospective design of this study.
For PS-PLIF, a bullet-type cage was inserted into the intervertebral bodies after performing laminectomy and medial resection of the bilateral facet joints. The outside was expanded to the transverse process, and the PS was then placed. For CBT-PLIF, the same procedure was used for decompression from the midline and placement of a bullet-type cage into the intervertebral bodies with medial resection of the bilateral facet joints. Screw installation was performed as per the CBT method [
In all of these three groups, locally harvested bone was used for bone grafting between vertebral bodies. No difference was noted in intraoperative hemostasis among the three groups. Furthermore, no posterolateral fusion was performed in any of the groups.
These three groups were compared in terms of patient characteristics (sex, age at time of surgery, body mass index, history, or comorbidities [i.e., hypertension, diabetes, cerebral infarction, myocardial infarction, and angina], and use of anticoagulation or antiplatelet medications [i.e., aspirin and warfarin]) and perioperative parameters (preoperative hemoglobin level; preoperative activated partial thromboplastin time; preoperative albumin level; operation time; intraoperative bleeding volume; postoperative drainage volume; total bleeding volume; and postoperative hemoglobin level at 1, 3, and 7 days after surgery). However, one patient in the CBT-PLIF group who received an intraoperative blood transfusion and one patient in the PS-PLIF group who received a transfusion the day after surgery were excluded from the perioperative blood data comparison. We have also compared perioperative complications and length of hospital stay. Other clinical results were excluded because of lacking data in terms of the Japanese Orthopedic Association scores. The use of closed suction drains for postoperative drainage was also examined.
Statistical analysis was performed using IBM SPSS Statistics ver. 20.0 (IBM Corp., Armonk, NY, USA). Continuous variables were compared using Mann-Whitney
The male-to-female ratio was 6-to-1 in the PS-PLIF group, 1-to-8 in the CBT-PLIF group, and 7-to-8 in the PPS-PLIF group. A significant difference was observed between the PS-PLIF and CBT-PLIF groups (
The prevalence of hypertension was determined to be at 7 1% (5 of 7) in the PS-PLIF group, 33% (3 of 9) in the CBT-PLIF group, and 53% (8 of 15) in the PPS-PLIF group. For diabetes, its prevalence rate was found to be 14% (1 of 7) in the PS-PLIF group, 22% (2 of 9) in the CBT-PLIF group, and 20% (3 of 15) in the PPS-PLIF group. The prevalence of angina was 14% (1 of 7) in the PS-PLIF group, 11% (1 of 9) in the CBT-PLIF group, and 13% (2 of 15) in the PPS-PLIF group. For myocardial infarction, its prevalence rate was 0% (0 of 7) in the PS-PLIF group, 11% (1 of 9) in the CBT-PLIF group, and 0% (0 of 15) in the PPS-PLIF group. The prevalence of cerebral infarction was 0% (0 of 7) in the PS-PLIF group, 0% (0 of 9) in the CBT-PLIF group, and 7% (1 of 15) in the PPS-PLIF group. Overall, no significant differences were noted in any comorbidities between the three groups (
The rate of aspirin use was determined to be 29% (2 of 7) in the PS-PLIF group, 11% (1 of 9) in the CBT-PLIF group, and 13% (2 of 15) in the PPS-PLIF group. The rate of warfarin use was 0% (0 of 7) in the PS-PLIF group, 11% (1 of 9) in the CBT-PLIF group, and 7% (1 of 15) in the PPS-PLIF group. There was no significant difference in either medication between the three groups. No significant difference was also noted in the proportion of patients with hypertension who were taking aspirin among the PS-PLIF (29% [2 of 7]), CBT-PLIF (11% [1 of 9]), and PPS-PLIF groups (7% [1 of 15]) (
The preoperative hemoglobin level was 14.2 g/dL (range, 11.6–15.1 g/dL) in the PS-PLIF group, 12.4 g/dL (range, 10.9–15.8 g/dL) in the CBT-PLIF group, and 13.4 g/dL (range, 8.8–15.7 g/dL) in the PPS-PLIF group. A significant difference was noted between the PS-PLIF and CBT-PLIF groups (
The total number of intervertebral decompression treatments of PLIF-adjacent segments was 1, 1, and 5 in the PS-PLIF, CBT-PLIF, and PPS-PLIF groups, respectively. The surgery time was 202.1 minutes (range, 137–334 minutes), 200.4 minutes (range, 131–264 minutes), and 183.3 minutes (range, 140–237 minutes), respectively. The intraoperative bleeding volume was 222.9 mL (range, 25–635 mL), 185.6 mL (range, 50–460 mL), and 152.7 mL (range, 60–305 mL), respectively. There were no significant differences between the three groups (
The postoperative drainage volume was 416.7 mL (range, 260–760 mL) in PS-PLIF group, 421.1 mL (range, 180–890 mL) in the CBT-PLIF group, and 210.1 mL (range, 50–367 mL) in the PPS-PLIF group. The volume was determined to be significantly lower in the PPS-PLIF group than in the PS-PLIF and CBT-PLIF groups (
The perioperative transfusion rate was 0.0% (0 of 7) in the PS-PLIF group, 11.1% (1 of 9) in the CBT-PLIF, and 6.7% (1 of 15) in the PPS-PLIF group. The reoperation rate for screw insertion was 0.0% (0 of 7) in the PS-PLIF group, 0.0% (0 of 9) in the CBT-PLOF group, and 6.7% (1 of 15) in the PPS-PLIF group. No significant difference in either parameter was noted between the three groups (
The following three types of postoperative closed suction drains were used: OrthoPAT (Haemonetics Corp., Braintree, MA, USA), SB VAC Super-Smooth (Sumitomo Bakelite Co. Ltd., Tokyo, Japan), and J-VAC combined with BLAKE Silicone Drain and J-VAC Suction Reservoir (Johnson & Johnson, New Brunswick, NJ, USA).
Surgical invasiveness is usually evaluated based on surgical time and intraoperative bleeding volume [
In both the PS-PLIF and CBT-PLIF groups, the postoperative drainage volume and the total amount of intraoperative bleeding were significantly greater than those in the PPS-PLIF group; furthermore, the postoperative drainage volume in both the PS-PLIF and CBT-PLIF groups was approximately double the intraoperative bleeding volume. This is a surprising result considering that no significant difference was noted in the intraoperative bleeding volume among the three groups. This indicates the inappropriateness of using the intraoperative bleeding volume alone in comparing surgery-related blood loss among different procedures.
Although the degree of muscle stripping required for surgery is similar between CBT-PLIF and PPS-PLIF, the current study demonstrated that the amount of postoperative drainage was significantly higher in PS-PLIF and CBT-PLIF with posterior instruments in the drainage space than in PPS-PLIF without posterior instruments at the same site. Therefore, the difference in the postoperative drainage volume among the three groups was considered to be associated with dead space expansion with posterior instruments because of the minimal surgery-related changes in the intervertebral body and medial lamina among the three groups. The surgical invasiveness of PPS-PLIF might be comparable to that of PLIF without PS. In fact, in a study by Park et al. [
With regard to postoperative soft tissue repair, a larger dead space and the instrument that forms it are associated with a risk of postoperative infection and are, therefore, clearly disadvantageous compared with the absence of instruments in a smaller dead space. A PPS covered with blood flow-rich muscle tissue is relatively resistant to postoperative infection. If it does become infected, it is located within a separate compartment from the anterior instrument, and the infection does not readily spread to the anterior compartment. Cizik et al. [
Our study has several limitations. First, the number of patients included in this study was very small, and it was a retrospective study conducted at a single center. Therefore, the study was statistically underpowered for complications that are not particularly frequent. However, even in this small patient population, the postoperative drainage volume and perioperative bleeding volume were determined to be significantly higher in the PS-PLIF and CBT-PLIF groups (with a posterior instrument in the same compartment as the anterior instrument) than in the PPS-PLIF group (with a posterior instrument in a different compartment than the anterior instrument). Second, the postoperative effluent was only part of the postoperative bleeding volume, and the hematoma remaining in the dead space formed by the surgery could not be evaluated. However, the remaining hematoma was predicted to be proportional to the size of the dead space and was not expected to affect the results. Third, the hematoma around the PPS was not evaluated. The dead space around the PPS is expected to be overwhelmingly smaller than the dead space formed by exfoliating the muscle from the bone. However, this result has to be verified in future studies. Although the PS-PLIF, CBT-PLIF, and PPS-PLF groups all had the same score using the invasiveness index established by Mirza et al. [
Evaluating surgical invasiveness using only the intraoperative bleeding amount can result in the underestimation of actual surgical invasiveness. Even with single-segment PLIF, the amount of perioperative bleeding can vary depending on the way the posterior instrument is installed.
No potential conflict of interest relevant to this article was reported.
We thank Angela Morben, DVM, ELS, from Edanz Group (
Characteristics of patients undergoing PS-PLIF, CBT-PLIF, and PPS-PLIF
Characteristic | PS-PLIF (n=7) | CBT-PLIF (n=9) | PPS-PLIF (n=15) | |
---|---|---|---|---|
Sex (male:female) | 6:1 |
1:8 |
7:8 | <0.001 |
Age (yr) | 61.3 (48–78) | 67.0 (32–82) | 65.3 (40–83) | NS |
Body mass index (kg/m2) | 24.1 (19.8–28.4) | 22.9 (18.0–27.9) | 23.2 (15.9–32.6) | NS |
Comorbidities | ||||
Hypertension | 5 (71) | 3 (33) | 8 (53) | NS |
Diabetes | 1 (14) | 2 (22) | 3 (20) | NS |
Angina | 1 (14) | 1 (11) | 2 (13) | NS |
Myocardial infarction | 0 | 1 (11) | 0 | NS |
Cerebral infarction | 0 | 0 | 1 (7) | NS |
Medication use | ||||
Aspirin | 2 (29) | 1 (11) | 2 (13) | NS |
Warfarin | 0 | 1 (11) | 1 (7) | NS |
Aspirin/hypertension | 2 (29) | 1 (11) | 1 (7) | NS |
Values are presented as number, mean (range), or number (%).
PS-PLIF, posterior lumbar interbody fusion with pedicle screws; CBT-PLIF, posterior lumbar interbody fusion with cortical bone trajectory screws; PPS-PLIF, posterior lumbar interbody fusion with percutaneous pedicle screws; NS, not significant.
Statistically significant difference.
Perioperative data of patients undergoing PS-PLIF, CBT-PLIF, and PPS-PLIF
Variable | PS-PLIF (n=7) | CBT-PLIF (n=9) | PPS-PLIF (n=15) | |
---|---|---|---|---|
Preoperative parameters | ||||
Hemoglobin (g/dL) | 14.2 (11.6–15.1) |
12.4 (10.9–15.8) |
13.4 (8.8–15.7) | <0.05 |
APTT (sec) | 28.6 (21.5–32.9) | 29.6 (26.7–33.2) | 29.8 (21.9–56.2) | NS |
Albumin (g/dL) | 4.64 (4.2–5.3) | 4.29 (3.9–4.7) | 4.19 (3.4–4.8) | NS |
Intraoperative parameters | ||||
Additional decompression | 1 | 1 | 5 | |
Operative time (min) | 202.1 (137–334) | 200.4 (131–264) | 183.3 (140–237) | NS |
Intraoperative blood loss (mL) | 222.9 (25–635) | 185.6 (50–460) | 152.7 (60–305) | NS |
Postoperative parameters | ||||
Postoperative drainage volume (mL) | 416.7 (260–760) |
421.1 (180–890) |
210.1 (50–367) |
0.002 |
Total amount of blood loss (mL) | 639.6 (285–1,000) |
606.7 (270–950) |
362.8 (145–637) |
0.01 |
Hemoglobin (g/dL) | ||||
1 Day after surgery | 11.96 (8.7–13.2) | 10.80 (9.7–14.2) |
11.91 (9.3–15.0) |
0.04 |
3 Days after surgery | 12.00 (8.6–13.2) | 11.19 (9.3–14.4) | 11.75 (10.0–14.3) | NS |
7 Days after surgery | 11.59 (8.3–13.1) | 10.49 (9.1–14.4) |
11.66 (9.7–14.0) |
0.03 |
Others | ||||
Hospital stay (day) | 21.4 (17–25) | 20.7 (18–28) | 21.7 (15–38) | NS |
Values are presented as mean (range). Additional decompression refers to the total number of intervertebral decompression treatments of PLIF-adjacent segments.
PS-PLIF, posterior lumbar interbody fusion with pedicle screws; CBT-PLIF, posterior lumbar interbody fusion with cortical bone trajectory screws; PPS-PLIF, posterior lumbar interbody fusion with percutaneous pedicle screws; APTT, activated partial thromboplastin time; NS, not significant.
Statistically significant.
Perioperative complications in patients undergoing PS-PLIF, CBT-PLIF, and PPS-PLIF
Variable | PS-PLIF (n=7) | CBT-PLIF (n=9) | PPS-PLIF (n=15) | |
---|---|---|---|---|
Blood transfusion | 0 | 1 (11.1) | 1 (6.7) | NS |
Reoperation for false screw insertion | 0 | 0 | 1 (6.7) | NS |
Dural injury | 0 | 0 | 0 | NS |
Reoperation for epidural hematoma | 0 | 0 | 0 | NS |
Reoperation for surgical site infection | 0 | 0 | 0 | NS |
Values are presented as number (%).
PS-PLIF, posterior lumbar interbody fusion with pedicle screw; CBT-PLIF, posterior lumbar interbody fusion with cortical bone trajectory screw; PPS-PLIF, posterior lumbar interbody fusion with percutaneous pedicle screw; NS, not significant.
Closed suction drains in patients undergoing PS-PLIF, CBT-PLIF, and PPS-PLIF
Variable | PS-PLIF (n=7) | CBT-PLIF (n=9) | PPS-PLIF (n=15) | |
---|---|---|---|---|
OrthoPAT (DTD: 5.0 mm) | 2 (28.6) | 0 | 0 | NS |
SB Vac Super Smooth (DTD: 5.0 mm) | 1 (14.3) | 1 (11.1) | 0 | NS |
SB Vac Super Smooth (DTD: 3.3 mm) | 3 (42.9) | 8 (88.9) |
7 (46.7) |
0.048 |
J-VAC (DTD: 5.0 mm) | 1 (14.3) | 0 |
6 (40.0) |
0.037 |
J-VAC (DTD: 3.5 mm) | 0 | 0 | 2 (13.3) | NS |
Values are presented as number (%).
PS-PLIF, posterior lumbar interbody fusion with pedicle screws; CBT-PLIF, posterior lumbar interbody fusion with cortical bone trajectory screws; PPS-PLIF, posterior lumbar interbody fusion with percutaneous pedicle screws; DTD, drain tube diameter; NS, not significant.
Statistically significant.
Perioperative data of patients undergoing PS-PLIF, CBT-PLIF, and PPS-PLIF using SB VAC Super-Smooth with 3.33-mm drain tube
Variable | PS-PLIF (n=3) | CBT-PLIF (n=9) | PPS-PLIF (n=8) | |
---|---|---|---|---|
Preoperative parameters | ||||
Hemoglobin (g/dL) | 14.5 (13.7–14.9) | 12.6 (10.9–15.8) | 13.4 (8.8–15.5) | NS |
APTT (sec) | 26.4 (21.5–32.9) | 29.3 (26.7–33.2) | 30.3 (21.9–56.2) | NS |
Intraoperative parameters | ||||
Operative time (min) | 183.7 (169–204) | 197.0 (131–264) | 196.3 (148–237) | NS |
Intraoperative blood loss (mL) | 158.3 (25–280) | 177.5 (50–460) | 147.1 (75–305) | NS |
Postoperative parameters | ||||
Postoperative drainage volume (mL) | 303.3 (260–360) |
417.5 (180–890) |
160.0 (50–260) |
0.02 |
Total amount of blood loss (mL) | 461.7 (285–570) | 595.0 (270–950) |
307.1 (145–565) |
0.009 |
Values are presented as mean (range).
PS-PLIF, posterior lumbar interbody fusion with pedicle screws; CBT-PLIF, posterior lumbar interbody fusion with cortical bone trajectory screws; PPS-PLIF, posterior lumbar interbody fusion with percutaneous pedicle screws; NS, not significant; APTT, activated partial thromboplastin time.
Statistically significant.