Postoperative spinal epidural hematoma in a biportal endoscopic spine surgery.

ABSTRACT: Biportal endoscopic spine surgery (BESS) is extending its application to most kind of spine surgeries. Postoperative spinal epidural hematoma (POSEH) is one of the major concerns of this emerging technique. Through this study we aim to investigate the incidence of POSEH in BESS comparing to a conventional spine surgery (CSS).The patients who underwent a non-fusion decompressive spine surgery due to degenerative lumbar spinal stenosis (LSS) or herniated lumbar disc (HLD) or both between January 2015 and March 2019 were reviewed retrospectively. The incidence of clinical POSEH that demanded a revision surgery for hematoma evacuation was compared between CSS and BESS. As a second endpoint, the morphometric degree of POSEH was compared between the two groups. The maximal compression of cauda equina by POSEH was measured by 4 grade scale at the T2 axial image and the neurological state was evaluated by 5 grade scale. The indication of hematoma evacuation was more than hG3 with more than nG1. As a subgroup analysis, risk factors of POSEH in BESS were investigated.The 2 groups were homogenous in age, sex, number and level of operated segments. There was significant difference in the incidence of symptomatic POSEH as 2/142 (1.4%) in CSS and 8/95 (8.4%) in BESS (P = .016). The radiological thecal sac compression by hematoma was hG1 65 (61.3%), hG2 35 (33.0%), hG3 5 (4.7%), hG4 1 (0.9%) cases in CSS and hG1 33 (39.8%), hG2 25 (30.1%), hG3 22 (26.5%), hG4 3 cases (3.6%) in BESS. The difference was significant (P < .001). In BESS subgroup analysis, the risk factor of high grade POSEH was bilateral laminectomy (OR = 8.893, P = .023).The incidence of clinical and morphometric POSEH was higher in BESS. In BESS, POSEH developed more frequently in bilateral laminectomy than unilateral laminectomy.

Clinical Effects and Complications of Pedicle Screw Augmentation with Bone Cement: Comparison of Fenestrated Screw Augmentation and Vertebroplasty Augmentation.

BACKGROUND: Pedicle screw augmentation with bone cement has been experimentally demonstrated to increase the pullout strength. However, the mechanisms of screw loosening are complicated and interacting. Although vertebroplasty augmentation and fenestrated screw augmentation have been compared in many studies, there has been no comparative study on their clinical effects and complications in real clinical settings. We investigated clinical effects of bone cement augmentation of a pedicle screw and differences according to augmentation methods. METHODS: Of the total 241 patients who had osteoporosis and underwent posterior pedicle screw fixation without anterior bone graft between January 2010 and December 2016, 132 patients with ≥2 years of radiological follow-up were included in this retrospective study. The patients were divided into group I (unaugmented) and group II (bone cement augmented). Group II was subdivided into II-S group (solid screw augmented) and II-F group (fenestrated screw augmented). The incidence of screw loosening was compared between groups I and II. Cement leakage, screw loosening, and screw fractures were investigated in the subgroups. RESULTS: In total, 36 of 71 (52%, group I) unaugmented cases and 96 of 170 (56%, group II) augmented cases were followed up for ≥2 years. Of the total 78 solid screw augmented cases, 42 (56%) were in II-S group; 54 of the total 92 (59%) fenestrated screw augmented cases were in II-F group. Groups I and II were homogenous regarding demographic characteristics; II-S and II-F groups were also homogenous. The incidence of screw loosening was 50.0% (18/36) in group I and 7.3% (7/96) in group II (p < 0.001). Cement leakage developed in 2 of 42 (4.8%) cases in II-S group and in 5 of 54 (9.3%) cases in II-F group (p = 0.462). Screw loosening developed in 6 of 42 (14.3%) cases in II-S group and in 1 of 54 cases (1.9%) in II-F group (p = 0.041). Screw fracture developed in none of 42 cases in II-S group and in 3 of 54 cases (5.6%) in II-F group (p = 0.254). CONCLUSIONS: In osteoporotic patients, bone cement augmentation of a pedicle screw decreased the incidence of screw loosening, and fenestrated screw augmentation was more effective than vertebroplasty augmentation.

Influence of Epidural Steroid Injection on Adrenal Function.

BACKGROUND: Spinal diseases are self-limited or non-progressive in many cases. Epidural steroid injection (ESI) is a common nonsurgical treatment option for spinal pain. Despite concerns about complications of repeated steroid injection, few studies reported on the adrenal function of spine disease patients undergoing surgery after ESI. We investigated the influence of preoperative multiple ESIs on adrenal function in spine surgery patients. METHODS: This was a retrospective study with prospective data collection. Those who underwent elective spinal operations and had a history of multiple ESIs from January to June 2017 were selected as a study group. Those who underwent knee arthroplasty and did not have a history of ESI and any kind of steroid injection in other areas during 6 months before surgery were selected as a control group. Demographic data were compared to assess homogeneity between groups. We assessed the preoperative serum cortisol level (SCL) to compare the basal adrenal function between groups. Also, we assessed the elevation of SCL postoperatively to evaluate the adrenal response to the surgical stress in each group. For subgroup analysis, we divided all patients into normal (7-28 µg/dL) and subnormal groups according to SCL and analyzed risk factors of adrenal suppression with multivariate logistic regression test. RESULTS: There were 53 patients in the study group and 130 in the control group. Age and sex were homogeneous between groups. There was significant intergroup difference in preoperative SCL (10.4 ± 4.8 µg/dL in the study group vs. 12.0 ± 4.2 µg/dL in the control group; p = 0.026).The postoperative day one SCL was 11.6 ± 5.0 µg/dL in the study group without significant increase from the preoperative level (p = 0.117), whereas the increase was significant in the control group with a postoperative level of 14.4 ± 4.4 µg/dL (p < 0.001). Among all patients, the SCL was subnormal in 18 patients and within the normal range in 165. Spine surgery was the independent risk factor irrespective of age and sex (odds ratio, 3.472; p = 0.015). CONCLUSIONS: Our results suggest that concern should be raised about the influence of preoperative multiple ESIs on adrenal suppression in spine surgery patients.

The Influence of Antiplatelet Drug Medication on Spine Surgery.

BACKGROUND: The incidence of cardiovascular and neurovascular diseases has been increasing with the aging of the population, and antiplatelet drugs (APDs) are more frequently used than in the past. With the average age of spinal surgery patients also increasing, there has been a great concern on the adverse effects of APD on spine surgery. To our knowledge, though there have been many studies on this issue, their results are conflicting. In this study, we aimed to determine the influence of APDs on spine surgery in terms of intraoperative bleeding and postoperative spinal epidural hematoma complication. METHODS: Patients who underwent posterior thoracolumbar decompression and instrumentation at our institution were reviewed. There were 34 APD takers (APDT group). Seventy-nine non-APD takers (NAPDT group) were selected as a control group in consideration of demographic and surgical factors. There were two primary endpoints of this study: the amount of bleeding per 10 minutes and cauda equina compression by epidural hematoma measured at the cross-sectional area of the thecal sac in the maximal compression site on the axial T2 magnetic resonance imaging scans taken on day 7. RESULTS: Both groups were homogeneous regarding age and sex (demographic factors), the number of fused segments, operation time, and primary/revision operation (surgical factors), and the number of platelets, prothrombin time, and activated partial thromboplastin time (coagulation-related factors). However, the platelet function analysis-epinephrine was delayed in the APDT group than in the NAPDT group (203.6 seconds vs. 170.0 seconds, p = 0.050). Intraoperative bleeding per 10 minutes was 40.6 ± 12.8 mL in the APDT group and 43.9 ± 9.9 mL in the NAPDT group, showing no significant difference between the two groups (p = 0.154). The cross-sectional area of the thecal sac at the maximal compression site by epidural hematoma was 120.2 ± 48.2 mm2 in the APDT group and 123.2 ± 50.4 mm2 in the NAPDT group, showing no significant difference between the two groups (p = 0.766). CONCLUSIONS: APD medication did not increase intraoperative bleeding and postoperative spinal epidural hematoma. Therefore, it would be safer to perform spinal surgery without discontinuation of APD therapy in patients who are vulnerable to cardiovascular and neurovascular complications.

Prognostic Factors of Neurological Complications in Spinal Surgeries.

STUDY DESIGN: Retrospective study. PURPOSE: To determine prognostic factors of neurological complications (NCs) of posterior thoracolumbar surgeries. OVERVIEW OF LITERATURE: There have been few reports on the prognosis of NCs according to the causes and treatment methods. METHODS: The subjects were 65 patients who had NCs for 19 years (1995-2013) after posterior thoracolumbar surgeries in Seoul Sacred Heart General Hospital. The degree of neurological injury was assessed using numeric scales as follows: G1, increased leg pain or sensory loss; G2, hemiparesis; G3, paraparesis; G4, cauda equine syndrome; and G5, complete paraplegia. The relative degree of neurological recovery was evaluated using four numeric scales as follows: Gr1, complete recovery; Gr2, almost complete recovery with residual sensory loss or numbness; Gr3, partial recovery with apparent neurological deficit; and Gr4, no recovery. The prognostic factors were investigated in terms of demographic and surgical variables that were available in a retrospective review. RESULTS: The causes were as follows: epidural hematoma (EH), 25 patients (38.5%); insufficient decompression and fusion, 14 patients (21.5%); mechanical injury, 11 patients (16.9%); insufficient discectomy, four patients (6.2%); and unknown, 11 patients (23.1%). The grade of neurological injury was as follows: G1, 11 patients (16.9%); G2, 34 patients (52.3%); G3, 15 patients (23.1%); G4, three patients (4.6%); and G5, two patients (3.1%). Thirteen patients received conservative treatment, and 52 underwent revision surgeries. Neurological recovery was as follows: Gr1, 21 patients (32.3%); Gr2, 17 patients (26.2%); Gr3, 20 patients (30.8%); and Gr4, seven patients (10.8%). The prognosis depended on the causes (p =0.041). The subgroup analysis of the revision group revealed a significant correlation between the degree of neurological recovery and the timing of revision, irrespective of causes (r =0.413, p =0.002). CONCLUSIONS: The prognosis of NC depended on the causes. EH was the best and unknown was the worst prognostic factor. Revision should be performed as soon as possible for a better prognosis.

Postoperative Spinal Epidural Hematoma: The Danger Caused by the Misuse of Thrombin-Containing Local Hemostatics.

STUDY DESIGN: Retrospective case-control study. PURPOSE: To examine the hypothesis that the misuse of thrombin-containing local hemostatics (TCLH) increases the risk of postoperative spinal epidural hematoma (POSEH). OVERVIEW OF LITERATURE: Many studies have focused on hypocoagulability as a risk factor for POSEH. However, there are no prior reports on the increased risk of POSEH in hypercoagulable states. METHODS: Posterior instrumented lumbar spine surgery cases over 2 consecutive years were divided into two groups: a study group (98 patients in whom TCLH was used) and a control group (176 patients in whom TCLH was not used). The excess TCLH matrix that was not associated with blood clot was not removed from the patients in the study group. The senior author decided whether to use TCLH or not. Suction drains were used in all patients. The demographics, coagulation-related factors, and intraoperative factors of the patients in the two groups were analyzed. The development of POSEH was compared between the two groups. RESULTS: The two groups were homogenous in demographics (age and sex), coagulation-related factors (platelet count, prothrombin time, activated partial thromboplastin time, and platelet function analysis), and surgical factors (total blood loss, operation time, blood loss/10 minutes, number of fusion segments, posterolateral fusion/posterior lumbar interbody fusion, and virgin or revision surgery). POSEH developed more frequently in the patients in the study group than in those in the control group (14/98 patients, 14.3% vs. 3/176 patients, 1.7%, respectively; p=0.001; odds ratio, 17.1). CONCLUSIONS: TCLH causes blood clot not only at the edge of damaged vessels but also at the site of extravascular blood. Excess TCLH matrix not associated with blood clot at the epidural space can enhance POSEH development because early clotted hematomas do not drain through suction drains.

Why Cannot Suction Drains Prevent Postoperative Spinal Epidural Hematoma?

BACKGROUND: Postoperative spinal epidural hematoma (POSEH) is different from spontaneous or post-spinal procedure hematoma because of the application of suction drains. However, it appeared that suction drains were not effective for prevention of POSEH in previous studies. The purpose of this study was to test our hypothesis that POSEH can be caused by hypercoagulability. METHODS: This was an experimental study. One hundred fifty milliliters of blood was donated from each of the 12 consecutive patients who underwent spine surgery and infused into 3 saline bags of 50 mL each. One of the 3 bags in each set contained 5,000 units of thrombin. All of them were connected to 120 ± 30 mmHg vacuum suctions: drainage was started 8 minutes after connection to the vacuum system for 12 normal blood bags (BV8) and 12 thrombin-containing blood bags (TBV8) and 15 minutes after connection for the remaining 12 normal blood bags (BV15). The amount of initial and remaining hematoma at 20 minutes, 120 minutes, and 24 hours after vacuum application were measured by their weight (g). The primary endpoint was the difference between BV8 and TBV8. The secondary end point was the difference between BV8 and BV15. RESULTS: The remaining hematoma in TBV8 was significantly greater than that in BV8 at all measurement points: 46.3 ± 12.4 vs. 17.0 ± 1.3 (p = 0.000) at 20 minutes; 33.0 ± 8.2 vs. 16.3 ± 1.2 (p = 0.000) at 120 minutes; and 26.1 ± 4.0 vs. 15.8 ± 1.6 (p = 0.000) at 24 hours after vacuum application. The remaining hematoma of BV15 was significantly greater than that of BV8 at all measurement points: 30.0 ± 12.0 vs. 17.0 ± 1.3 (p = 0.002) at 20 minutes; 24.2 ± 7.6 vs. 16.3 ± 1.2 at 120 minutes (p = 0.002); and 22.2 ± 6.6 vs. 15.8 ± 1.6 (p = 0.004) at 24 hours after vacuum application. CONCLUSIONS: With a suction drain in place, the amount of remaining hematoma could be affected by coagulability. Thrombin-containing local hemostatics and the length of time elapsed before the commencement of suction resulted in hypercoagulability, indicating these two factors could be causes of POSEH.

The Survivorship and Clinical Results of Minimally Invasive Unicompartmental Knee Arthroplasty at 10-Year Follow-up.

BACKGROUND: In this study, we investigated the long-term clinical results and survival rate of minimally invasive unicompartmental knee arthroplasty (UKA) by collecting cases that had been implanted more than 10 years ago. METHODS: One hundred and twenty-eight patients (166 cases) who underwent Oxford phase 3 medial UKA using the minimally invasive surgery from January 2002 to December 2002 were selected. The mean age of the patients at the time of surgery was 61 years, and the duration of the follow-up was minimum 10 years. Clinical and radiographic assessments were performed using the Knee Society clinical rating system, and the survival analysis was done by the Kaplan-Meier method with 95% confidence interval (CI). RESULTS: The mean Knee Society knee and function scores improved significantly from 53.8 points (range, 25 to 70 points) and 56.1 points (range, 35 to 80 points) preoperatively to 85.4 points (range, 58 to 100 points) and 80.5 points (range, 50 to 100 points) at 10-year follow-up, respectively (p < 0.001). Failures following the UKA occurred in 16 cases (9.6%), and the mean time of the occurrence of the failure was 6.2 years after the surgery. The 10-year survival rate was 90.5% (95% CI, 85.9 to 95.0) when failure was defined as all the reoperations, whereas the 10-year survival rate was 93.4% (95% CI, 89.6 to 97.1) when the cases in which only revision total knee arthroplasty was defined as failure. CONCLUSIONS: The results of this study show outstanding functions of the knee joint and satisfactory 10-year survival rate after minimally invasive UKA. Therefore, minimally invasive UKA could be a useful method in the treatment of osteoarthritis in one compartment of knee joint.