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Yu Yamato, Tomohiko Hasegawa, Sho Kobayashi, Tatsuya Yasuda, Daisuke Togawa, Go Yoshida, Tomohiro Banno, Shin Oe, Yuki Mihara, and Yukihiro Matsuyama

OBJECTIVE

Despite the significant incidence of rod fractures (RFs) following long-segment corrective fusion surgery, little is known about the optimal treatment strategy. The objectives of this study were to investigate the time course of clinical symptoms and treatments in patients with RFs following adult spinal deformity (ASD) surgery and to establish treatment recommendations.

METHODS

This study was a retrospective case series of patients with RFs whose data were retrieved from a prospectively collected single-center database. The authors reviewed the cases of 304 patients (mean age 62.9 years) who underwent ASD surgery. Primary symptoms, time course of symptoms, and treatments were investigated by reviewing medical records. Standing whole-spine radiographs obtained before and after RF development and at last follow-up were evaluated. Osseous union was assessed using CT scans and intraoperative findings.

RESULTS

There were 54 RFs in 53 patients (mean age 68.5 years [range 41–84 years]) occurring at a mean of 21 months (range 6–47 months) after surgery. In 1 patient RF occurred twice, with each case at a different time and level, and the symptoms and treatments for these 2 RFs were analyzed separately (1 case of revision surgery and 1 case of nonoperative treatment). The overall rate of RF observed on radiographs after a minimum follow-up of 1 year was 18.0% (54 of 300 cases). The clinical symptoms at the time of RF were pain in 77.8% (42 of 54 cases) and no onset of new symptoms in 20.5% (11 of 54 cases). The pain was temporary and had subsided in 19 of 42 cases (45%) within 2 weeks. In 36 of the 54 cases (66.7%) (including the first RF in the patient with 2 RFs), patients underwent revision surgery at a mean of 116 days (range 5–888 days) after diagnosis. In 18 cases patients received only nonoperative treatment as of the last follow-up, including 17 cases in which the patients experienced no pain and no remarkable progression of deformity (mean 18.5 months after RF development).

CONCLUSIONS

This analysis of 54 RFs in 53 patients following corrective fusion surgery for ASD demonstrates a relationship between symptoms and alignment change. Revision surgeries were performed in a total of 36 cases. Nonoperative care was offered in 18 (33.3%) of 54 cases at the last follow-up, with no additional symptoms in 17 of the 18 cases. These data offer useful information regarding informed decision making for patients in whom an RF occurs after ASD surgery.

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Hiroki Ushirozako, Go Yoshida, Sho Kobayashi, Tomohiko Hasegawa, Yu Yamato, Tatsuya Yasuda, Tomohiro Banno, Hideyuki Arima, Shin Oe, Yuki Mihara, Daisuke Togawa, and Yukihiro Matsuyama

OBJECTIVE

Intraoperative neuromonitoring may be valuable for predicting postoperative neurological complications, and transcranial motor evoked potentials (TcMEPs) are the most reliable monitoring modality with high sensitivity. One of the most frequent problems of TcMEP monitoring is the high rate of false-positive alerts, also called “anesthetic fade.” The purpose of this study was to clarify the risk factors for false-positive TcMEP alerts and to find ways to reduce false-positive rates.

METHODS

The authors analyzed 703 patients who underwent TcMEP monitoring under total intravenous anesthesia during spinal surgery within a 7-year interval. They defined an alert point as final TcMEP amplitudes ≤ 30% of the baseline. Variations in body temperature (maximum − minimum body temperature during surgery) were measured. Patients with false-positive alerts were classified into 2 groups: a global group with alerts observed in 2 or more muscles of the upper and lower extremities, and a focal group with alerts observed in 1 muscle.

RESULTS

False-positive alerts occurred in 100 cases (14%), comprising 60 cases with global and 40 cases with focal alerts. Compared with the 545 true-negative cases, in the false-positive cases the patients had received a significantly higher total propofol dose (1915 mg vs 1380 mg; p < 0.001). In the false-positive cases with global alerts, the patients had also received a higher mean propofol dose than those with focal alerts (4.5 mg/kg/hr vs 4.2 mg/kg/hr; p = 0.087). The cutoff value of the total propofol dose for predicting false-positive alerts, with the best sensitivity and specificity, was 1550 mg. Multivariate logistic analysis revealed that a total propofol dose > 1550 mg (OR 4.583; 95% CI 2.785–7.539; p < 0.001), variation in body temperature (1°C difference; OR 1.691; 95% CI 1.060–2.465; p < 0.01), and estimated blood loss (500-ml difference; OR 1.309; 95% CI 1.155–1.484; p < 0.001) were independently associated with false-positive alerts.

CONCLUSIONS

Intraoperative total propofol dose > 1550 mg, larger variation in body temperature, and greater blood loss are independently associated with false-positive alerts during spinal surgery. The authors believe that these factors may contribute to the false-positive global alerts that characterize anesthetic fade. As it is necessary to consider multiple confounding factors to distinguish false-positive alerts from true-positive alerts, including variation in body temperature or ischemic condition, the authors argue the importance of a team approach that includes surgeons, anesthesiologists, and medical engineers.

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Tomohiro Banno, Yu Yamato, Hiroki Oba, Tetsuro Ohba, Tomohiko Hasegawa, Go Yoshida, Hideyuki Arima, Shin Oe, Yuki Mihara, Hiroki Ushirozako, Jun Takahashi, Hirotaka Haro, and Yukihiro Matsuyama

OBJECTIVE

L3 is most often selected as the lowest instrumented vertebra (LIV) to conserve mobile segments in fusion surgery; however, in cases with the lowest end vertebra (LEV) at L4, LIV selection as L3 could have a potential risk of correction loss and coronal decompensation. This study aimed to compare the clinical and radiographic outcomes depending on the LEV in adolescent idiopathic scoliosis (AIS) patients with Lenke type 5C curves.

METHODS

Data from 49 AIS patients with Lenke type 5C curves who underwent selective thoracolumbar/lumbar (TL/L) fusion to L3 as the LIV were retrospectively analyzed. The patients were classified according to their LEVs into L3 and L4 groups. In the L4 group, subanalysis was performed according to the upper instrumented vertebra (UIV) level toward the upper end vertebra (UEV and 1 level above the UEV [UEV+1] subgroups). Radiographic parameters and clinical outcomes were compared between these groups.

RESULTS

Among 49 patients, 32 and 17 were in the L3 and L4 groups, respectively. The L4 group showed a lower TL/L curve correction rate and a higher subjacent disc angle postoperatively than the L3 group. Although no intergroup difference was observed in coronal balance (CB), the L4 group showed a significantly higher main thoracic (MT) and TL/L curve progression during the postoperative follow-up period than the L3 group. In the L4 group, the UEV+1 subgroup showed a higher absolute value of CB at 2 years than the UEV subgroup.

CONCLUSIONS

In Lenke type 5C AIS patients with posterior selective TL/L fusion to L3 as the LIV, patients with their LEVs at L4 showed postoperative MT and TL/L curve progression; however, no significant differences were observed in global alignment and clinical outcome.

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Hiroki Ushirozako, Tomohiko Hasegawa, Yu Yamato, Go Yoshida, Tatsuya Yasuda, Tomohiro Banno, Hideyuki Arima, Shin Oe, Yuki Mihara, Tomohiro Yamada, Koichiro Ide, Yuh Watanabe, Keichi Nakai, Takaaki Imada, and Yukihiro Matsuyama

OBJECTIVE

Surgical site infection (SSI) after posterior spinal surgery is one of the severe complications that may occur despite administration of prophylactic antibiotics and the use of intraoperative aseptic precautions. The use of intrawound vancomycin powder for SSI prevention is still controversial, with a lack of high-quality and large-scale studies. The purpose of this retrospective study using a propensity score–matched analysis was to clarify whether intrawound vancomycin powder prevents SSI occurrence after spinal surgery.

METHODS

The authors analyzed 1261 adult patients who underwent posterior spinal surgery between 2010 and 2018 (mean age 62.3 years; 506 men, 755 women; follow-up period at least 1 year). Baseline and surgical data were assessed. After a preliminary analysis, a propensity score model was established with adjustments for age, sex, type of disease, and previously reported risk factors for SSI. The SSI rates were compared between patients with intrawound vancomycin powder treatment (vancomycin group) and those without (control group).

RESULTS

In a preliminary analysis of 1261 unmatched patients (623 patients in the vancomycin group and 638 patients in the control group), there were significant differences between the groups in age (p = 0.041), body mass index (p = 0.013), American Society of Anesthesiologists classification (p < 0.001), malnutrition (p = 0.001), revision status (p < 0.001), use of steroids (p = 0.019), use of anticoagulation (p = 0.033), length of surgery (p = 0.003), estimated blood loss (p < 0.001), and use of instrumentation (p < 0.001). There was no significant difference in SSI rates between the vancomycin and control groups (21 SSIs [3.4%] vs 33 SSIs [5.2%]; OR 0.640, 95% CI 0.368–1.111; p = 0.114). Using a one-to-one propensity score–matched analysis, 444 pairs of patients from the vancomycin and control groups were selected. There was no significant difference in the baseline and surgical data, except for height (p = 0.046), between both groups. The C-statistic for the propensity score model was 0.702. In the score-matched analysis, 12 (2.7%) and 24 (5.4%) patients in the vancomycin and control groups, respectively, developed SSIs (OR 0.486, 95% CI 0.243–0.972; p = 0.041). There were no systemic complications related to the use of vancomycin.

CONCLUSIONS

The current study showed that intrawound vancomycin powder was useful in reducing the risk of SSI after posterior spinal surgery by half, without adverse events. Intrawound vancomycin powder use is a safe and effective procedure for SSI prevention.

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Shin Oe, Yu Yamato, Tomohiko Hasegawa, Go Yoshida, Sho Kobayashi, Tatsuya Yasuda, Tomohiro Banno, Hideyuki Arima, Yuki Mihara, Hiroki Ushirozako, Tomohiro Yamada, Koichiro Ide, Yuh Watanabe, and Yukihiro Matsuyama

OBJECTIVE

Many complications are likely to occur in patients with malnutrition. The prognostic nutritional index (PNI) is often used when evaluating a patient’s nutritional condition. However, no studies have investigated the association between nutritional status and postoperative medical complications or prognosis by using the PNI in the field of spinal surgery. The purpose of this retrospective study was to investigate postoperative medical complications and prognoses of patients who had undergone adult spinal deformity (ASD) surgery, according to their preoperative nutritional status.

METHODS

All patients aged ≥ 40 years who had undergone scheduled ASD surgery in the authors’ hospital between March 2010 and June 2017 were eligible for study inclusion and were divided into groups according to their PNI (< 50, group L; ≥ 50, group H). Medical complications diagnosed within 30 days postoperatively were evaluated; however, surgical site infection and death were evaluated until 1 and 5 years after surgery, respectively.

RESULTS

Among the 285 eligible patients, groups L and H consisted of 118 and 167 patients, whose mean ages were 68.6 and 68.3 years, respectively. There was a significant difference in body mass index (22 vs 24 mg/kg2, respectively, p = 0.000), PNI (46 vs 55, p = 0.000), comorbidity of osteoporosis (50% vs 32%, p = 0.005) and autoimmune disease (13% vs 5%, p = 0.036), medical history of malignant disorder (17% vs 6%, p = 0.007), and medical complications (49% vs 23%, p = 0.000) between groups L and H. Multiple logistic regression analysis suggested that significant risk factors for postoperative medical complications were male sex (p = 0.000, OR 3.5, 95% CI 1.78–6.96), PNI < 50 (p = 0.000, OR 2.9, 95% CI 1.69–4.93), and days to ambulation (p = 0.003, OR 1.1, 95% CI 1.02–1.09).

CONCLUSIONS

Medical complication rates are significantly higher in patients with PNI < 50, those with delayed ambulation, and male patients. In malnourished patients scheduled for ASD surgery, improvement of preoperative nutritional status and postoperative early ambulation are important to avoid medical complications.

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Hideyuki Arima, Tomohiko Hasegawa, Yu Yamato, Go Yoshida, Tomohiro Banno, Shin Oe, Yuki Mihara, Hiroki Ushirozako, Tomohiro Yamada, Yuh Watanabe, Koichiro Ide, Keiichi Nakai, Kenta Kurosu, and Yukihiro Matsuyama

OBJECTIVE

Achievement of minimal clinically important differences (MCIDs) in the Scoliosis Research Society–22r (SRS-22r) subdomains represents surgical efficacy. However, whether achievements of MCIDs in SRS-22r domains are associated with long-term satisfaction in patients with adult spinal deformity (ASD) is unclear. This study aimed to elucidate factors affecting patient satisfaction after thoracopelvic corrective fusion surgery in patients with ASD.

METHODS

Data obtained in 187 patients with ASD who underwent extensive corrective fusion surgery from the thoracic spine to the pelvis between 2010 and 2017 and underwent follow-up for 2 years were retrospectively reviewed. The authors investigated the likelihood of achieving MCIDs in the function, pain, self-image, mental health, and subtotal domains 2 years after surgery. The following MCID values were used: function, 0.90; pain, 0.85; self-image, 1.05; mental health, 0.70; and subtotal, 1.05. Multivariate analysis was performed to evaluate factors associated with patient satisfaction 2 years after surgery.

RESULTS

The average satisfaction scores in the group that achieved MCID and the group that did not were as follows: 3.97 and 3.37 for function (p < 0.001), 3.66 and 3.51 for pain (p = 0.221), 3.84 and 3.06 for self-image (p < 0.001), 3.82 and 3.28 for mental health (p < 0.001), and 3.96 and 3.30 for subtotal (p < 0.001), respectively. Except for the pain domain, the group that achieved MCIDs showed greater satisfaction than the group that did not achieve MCIDs. On multivariate analysis, factors related to postoperative satisfaction were achievement of SRS-22r self-image (standardization coefficient 0.322, p < 0.001) and function (standardization coefficient 0.179, p = 0.026) MCIDs. Perioperative complications and revision surgery were not related to patient satisfaction.

CONCLUSIONS

Multivariate analysis demonstrated that achievement of MCIDs in SRS-22r self-image and function domains was significantly associated with postoperative satisfaction. Given that patients with poor preoperative health-related quality of life are more likely to achieve MCIDs in SRS-22r domains, surgeons should carefully consider whether to operate on patients with relatively good baseline health-related quality of life when making surgical decisions.