Perioperative complications of spine surgery in patients 80 years of age or older: a multicenter prospective cohort study

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OBJECTIVE

The number of spine surgeries performed in elderly patients is consistently increasing. However, to date the prevalence of and risk factors for perioperative complications remain unclear, especially in patients 80 years of age or older. This study had two goals: 1) determine the perioperative complications of spine surgery associated with patients 80 years of age or older; and 2) investigate the risk factors for perioperative systemic complications.

METHODS

In this paper, the authors describe a multicenter prospective cohort study. Seven spine centers with board-certified spine surgeons participated in this all-case investigation. A total of 270 consecutively enrolled patients (109 males and 161 females), 80 years of age or older, underwent spine surgery between January and December 2017. Patients with trauma, infection, or tumor were excluded in this cohort. Perioperative complications were defined as adverse events that occurred intraoperatively or within 30 days postoperatively. The patients’ preoperative health status was determined using the following means of assessment: 1) the Charlson Comorbidity Index, 2) the American Society of Anesthesiologists Physical Status Classification System, 3) the Eastern Cooperative Oncology Group Performance Status (ECOG-PS), 4) the presence of sarcopenia, and 5) the Geriatric Nutritional Risk Index. Associations among patient age, preoperative health status, surgical factors (instrumentation surgery, operation time, number of spinal levels treated, and estimated blood loss), and perioperative systemic complications were analyzed.

RESULTS

Overall perioperative, surgical site, and minor systemic complications were observed in 20.0%, 8.1%, and 14.8% of patients, respectively. Major systemic complications, on the other hand, were not observed. The reoperation rate was low—only 4.1%. Multivariate analysis revealed that the ECOG-PS (p = 0.013), instrumentation surgery (p = 0.024), and an operation time longer than 180 minutes (p = 0.016) were associated with minor systemic complications.

CONCLUSIONS

To the best of the authors’ knowledge, this is the first multicenter prospective all-case investigation of perioperative complications of spine surgery in elderly patients. Although decreased daily activity (ECOG-PS), instrumentation surgery, and longer operation time were associated with minor systemic complications, no major systemic complications were observed in these elderly patients. Thus, spine surgery can be safely performed in elderly patients 80 years of age or older.

ABBREVIATIONS ADL = activity of daily living; ASA-PS = American Society of Anesthesiologists Physical Status; BKP = balloon kyphoplasty; CCI = Charlson Comorbidity Index; CI = confidence interval; EBL = estimated blood loss; ECOG-PS = Eastern Cooperative Oncology Group Performance Status; GNRI = Geriatric Nutritional Risk Index; OR = odds ratio; UTI = urinary tract infection.

OBJECTIVE

The number of spine surgeries performed in elderly patients is consistently increasing. However, to date the prevalence of and risk factors for perioperative complications remain unclear, especially in patients 80 years of age or older. This study had two goals: 1) determine the perioperative complications of spine surgery associated with patients 80 years of age or older; and 2) investigate the risk factors for perioperative systemic complications.

METHODS

In this paper, the authors describe a multicenter prospective cohort study. Seven spine centers with board-certified spine surgeons participated in this all-case investigation. A total of 270 consecutively enrolled patients (109 males and 161 females), 80 years of age or older, underwent spine surgery between January and December 2017. Patients with trauma, infection, or tumor were excluded in this cohort. Perioperative complications were defined as adverse events that occurred intraoperatively or within 30 days postoperatively. The patients’ preoperative health status was determined using the following means of assessment: 1) the Charlson Comorbidity Index, 2) the American Society of Anesthesiologists Physical Status Classification System, 3) the Eastern Cooperative Oncology Group Performance Status (ECOG-PS), 4) the presence of sarcopenia, and 5) the Geriatric Nutritional Risk Index. Associations among patient age, preoperative health status, surgical factors (instrumentation surgery, operation time, number of spinal levels treated, and estimated blood loss), and perioperative systemic complications were analyzed.

RESULTS

Overall perioperative, surgical site, and minor systemic complications were observed in 20.0%, 8.1%, and 14.8% of patients, respectively. Major systemic complications, on the other hand, were not observed. The reoperation rate was low—only 4.1%. Multivariate analysis revealed that the ECOG-PS (p = 0.013), instrumentation surgery (p = 0.024), and an operation time longer than 180 minutes (p = 0.016) were associated with minor systemic complications.

CONCLUSIONS

To the best of the authors’ knowledge, this is the first multicenter prospective all-case investigation of perioperative complications of spine surgery in elderly patients. Although decreased daily activity (ECOG-PS), instrumentation surgery, and longer operation time were associated with minor systemic complications, no major systemic complications were observed in these elderly patients. Thus, spine surgery can be safely performed in elderly patients 80 years of age or older.

ABBREVIATIONS ADL = activity of daily living; ASA-PS = American Society of Anesthesiologists Physical Status; BKP = balloon kyphoplasty; CCI = Charlson Comorbidity Index; CI = confidence interval; EBL = estimated blood loss; ECOG-PS = Eastern Cooperative Oncology Group Performance Status; GNRI = Geriatric Nutritional Risk Index; OR = odds ratio; UTI = urinary tract infection.

In Brief

The primary contribution of this paper is that it demonstrates the safety of spine surgery in patients 80 years of age or older. The authors believe that this contribution will be helpful to spine surgeons who treat elderly patients suffering from spinal diseases.

The number of people 60 years of age or older is increasing throughout the world: one in five individuals will be 60 years or older by 2050.32 The number of persons 80 years or older was 125 million in 2015; this number will reach 434 million in 2050.

Spinal degenerative diseases, such as lumbar spinal stenosis, cervical spondylotic myelopathy, degenerative spondylolisthesis, and osteoporotic vertebral fracture, generally develop with advancing age.10 Based on a Japanese nationwide cohort study,15 approximately 600 spine surgeries (3.8% of all surgeries) were performed in patients older than 80 years of age in 2001. In the following decade, this number significantly increased fivefold to 3000 or more (10% of all surgeries in 2011). Japan has the highest aging population in the world, and elderly patients requiring spine surgery may be recognized globally as a group in the future.

Spine surgery for elderly patients (defined as 65 years and older) is considered effective in improving quality of life;20,30 it is also cost-effective.8 Surgical treatment is considered beneficial for elderly patients 80 years or older as well as for patients younger than 80 years,29 and the efficacy of surgical treatment in these age groups is well maintained even after long-term follow-up.12,19,29

Nevertheless, one should pay careful attention to perioperative complications in elderly patients. Hamel et al. showed that 20% of patients 80 years of age or older who underwent major noncardiac surgery experienced one or more postoperative complications.13 These authors also mentioned that mortality rates were higher in elderly patients than in younger patients (8.2% vs 2.8%). The rate of perioperative complications in spine surgery has been reported to range from 5.6% to 35% in patients 80 years of age or older.12,16,18,19,21,24,26,28,34

The majority of earlier studies on perioperative complications were retrospective. One systematic review showed that the incidence of complications was higher in prospective studies than in retrospective studies (19.9% vs 16.1%).22 Previous studies revealed several risk factors, such as older age, presence of comorbidities, estimated blood loss (EBL), and the number of spinal levels that were treated, to be associated with perioperative complications of spine surgery in elderly patients.3,4,14,33 Some recent studies showed an association between perioperative complications of spine surgery and frailty, sarcopenia, or malnutrition,1,27,35 whereas other studies did not reveal any association between these factors.5 Given the disagreement, the association between perioperative complications of spine surgery and frailty, sarcopenia, and malnutrition remains unclear.

Surgeons are reluctant to perform spine surgery in elderly patients because of the high risk of perioperative complications due to the patient’s advanced age. Moreover, the prevalence and risk factors of perioperative complications remain unclear, specifically for elderly patients who are 80 years or older. Spine surgeons therefore need more reliable data on which to determine the indications for surgical treatment. For that reason, we conducted a prospective all-case investigation. The study had two goals: 1) determine the perioperative complications of spine surgery associated with patients 80 years of age or older; and 2) investigate the risk factors for perioperative systemic complications.

Methods

Seven spine centers staffed with board-certified spine surgeons participated in this multicenter prospective cohort study in Hokkaido, Japan. The current study protocol was fully approved by the local institutional review board, and informed consent was obtained from the study participants. A total of 2847 spine surgeries were performed in 2017. Surgical treatment was indicated in patients who experienced disabilities that impacted their daily living due to pain after ineffective nonoperative treatment and/or neurological deficit: all participants were willing to undergo surgery and had sufficient knowledge of the potential risks of the surgery. In this study, we analyzed data from 270 consecutively enrolled patients who had undergone an elective spine surgery when 80 years or older (9.5% of the entire patient population); patients with trauma, infection, or tumor were excluded. Surgical interventions for pathological disorders related to osteoporosis were included in this study. Apart from balloon kyphoplasty (BKP), all posterior lumbar surgeries were performed by open procedures at our spine centers, and there were no cases of endoscopic surgery in the current study. A total of 109 males and 161 females with a mean age of 83.2 years (range 80–99 years) were included in the study (Fig. 1). Perioperative complications and potential risk factors were assessed by prospective observation. In this population, 213 patients (78.9%) were discharged home, and 57 patients (21.1%) were discharged to a facility other than home.

FIG. 1.
FIG. 1.

Bar graph demonstrating the patient distribution by age. The y-axis represents the number of patients and the x-axis represents patients’ ages in years.

Surgical Factors

Surgical factors analyzed included the following: operative level (cervical, thoracic, and thoracolumbar–lumbosacral spine), surgical procedure (decompression, instrumentation surgery, and BKP), operation time, number of spinal levels treated, and EBL.

Perioperative Complications

Perioperative complications were defined as adverse events that occurred intraoperatively or within 30 days postoperatively. We divided all complications into three categories: surgical site complications, major systemic complications, and minor systemic complications. Surgical site complications included dural tear, hematoma requiring surgery, surgical wound disruption, and surgical site infection. Complications specific to instrumentation surgery or BKP were also investigated. Major systemic complications were defined as complications that were potentially life-threatening or that led to prolonged hospitalization. Complications that we routinely investigated are listed in Table 1.

TABLE 1.

Perioperative complications in 270 patients, 80 years of age or older, who underwent spine surgery

ComplicationNo. of Patients (%)Reop Required (%)
Total54 (20.0)*
Surgical site complication
 Total22 (8.1)11 (4.1)
 Dural tear6 (2.2)1
 Hematoma2 (0.7)2
 Surgical wound disruption2 (0.7)1
 Superficial wound infection5 (1.9)1
 Deep wound infection1 (0.4)1
 Complication specific to instrumentation (132 patients)
  Total6 (4.5)4
  Fracture of lower instrumented vertebra3 (2.3)2
  Pedicle screw back-out after surgery2 (1.5)2
  Pedicle fracture1 (0.8)0
  Pedicle screw deviation0 (0.0)0
  Cage back-out after surgery0 (0.0)0
 Complication specific to BKP (32 patients)
  Adjacent-level fracture1 (3.1)1
Major systemic complication
 Total0 (0.0)
 Acute coronary syndrome0 (0.0)
 Cardiac failure0 (0.0)
 Cerebrovascular disease0 (0.0)
 Pneumonia0 (0.0)
 Venous thrombosis0 (0.0)
 Renal failure requiring dialysis0 (0.0)
 Peptic ulcer0 (0.0)
 Ileus0 (0.0)
 Cholangitis0 (0.0)
 Cholecystitis0 (0.0)
Minor systemic complication
 Total40 (14.8)
 Anemia requiring transfusion20 (7.4)
 Delirium17 (6.3)
 UTI7 (2.6)
— = not applicable.

In eight patients both a surgical site complication and a minor systemic complication developed.

A dural tear and a pedicle fracture occurred in the same patient.

In two patients both anemia and a UTI developed; in one patient both delirium and anemia developed; and in another patient both delirium and a UTI developed.

Preoperative Health Status

The patients’ preoperative health status was determined using the following means of assessment: 1) the Charlson Comorbidity Index (CCI),6 2) the American Society of Anesthesiologists Physical Status (ASA-PS) Classification System,9 3) the Eastern Cooperative Oncology Group Performance Status (ECOG-PS),23 4) the presence of sarcopenia, and 5) the Geriatric Nutritional Risk Index (GNRI).2

The CCI is a method that assesses comorbidity. The total score is obtained by adding the relative weight of each comorbidity. For example, myocardial infarction, congestive heart failure, cerebrovascular disease, asthma, diabetes, and hypertension are each given a score of 1; renal disease, mild liver disease, and cancer, a score of 2; severe liver disease, a score of 3; and metastatic solid tumor or human immunodeficiency virus, a score of 6.

The ASA-PS Classification System aids in the assessment of the general condition of patients before surgery. Class I indicates a normal healthy patient; class II, a patient with mild systemic disease; class III, a patient with severe systemic disease; class IV, a patient with a severe and life-threatening systemic disease; class V, a moribund patient who is not expected to survive without the operation; and class VI, a patient who has been declared brain dead and whose organs will be removed for donation. As a matter of course, patients 80 years of age or older were assigned to class II or greater.

The ECOG-PS is a measurement of activities of daily living (ADLs) in patients with cancer (Table 2). We find this assessment useful in all patients regardless of whether they have cancer.

TABLE 2.

Eastern Cooperative Oncology Group Performance Status*

GradeActivity of Daily Living
0Fully active, able to carry on all pre-disease performance w/o restriction
1Restricted in physically strenuous activity but ambulatory & able to carry out work of a light or sedentary nature, e.g., light house work, office work
2Ambulatory & capable of all self-care but unable to carry out any work activities; up & about >50% of waking hours
3Capable of only limited self-care; confined to bed or chair >50% of waking hours
4Completely disabled; cannot carry on any self-care; totally confined to bed or chair
5Dead

Based on Oken MM et al: Toxicity and response criteria of the Eastern Cooperative Oncology Group. Am J Clin Oncol 5:649–655, 1982.

Sarcopenia is a syndrome characterized by the loss of muscle mass and strength.7 We assessed sarcopenia by using a simplified method reported by Shimokata and Ando.31 Patients with a grip strength less than 25 kg in males or less than 20 kg in females, and a body mass index less than 18.5 kg/m2 or a calf girth less than 30 cm were diagnosed with sarcopenia by using this method.

The GNRI is an index of the nutrition condition of elderly patients; it is used to predict the risk of morbidity and mortality in hospitalized elderly patients. This index is calculated from the patient’s serum albumin, weight, and ideal weight. The GNRI has the following grading system: > 98 = absence of nutrition-related risk; 92 to ≤ 98 = low risk; 82 to < 92 = moderate risk; and < 82 = major risk.

All these scores were assessed after patients decided to undergo surgical treatment. No patients were excluded from surgical consideration based on these scores.

Statistical Analyses

Associations among patients’ age (80–84, 85–89, or ≥ 90 years), patients’ preoperative health status (CCI, ASA-PS, and ECOG-PS grades, presence or absence of sarcopenia; and nutritional risk assessed by the GNRI [no risk, low risk, moderate risk, or major risk]), surgical factors (surgery involved instrumentation or not, operation time > 180 minutes, number of spinal levels treated ≥ 3, and EBL > 500 ml), and systemic perioperative complications were analyzed using Pearson’s chi-square test and logistic regression analysis for the univariate analysis. A multivariate logistic regression model was constructed for the multivariate analysis by using explanatory variables selected by stepwise multiple regression. All statistical analyses were performed using JMP Pro 13 (SAS). A p value < 0.05 was considered statistically significant.

Results

Surgical Factors

Surgical factors are listed in Table 3. The operative spine level was cervical in 32 patients, thoracic in nine patients, and thoracolumbar–lumbosacral in 231 patients (two patients underwent cervical and thoracolumbar–lumbosacral surgery simultaneously). The surgical procedure performed was posterior decompression in 106 patients, instrumentation surgery in 132 patients, and BKP in 32 patients. The mean duration of the operation was 119.8 minutes (range 25–678 minutes). The mean number of operative spine levels that were treated was 1.87 (range 0–9 levels). The average EBL was 146.2 ml (range 0–1160 ml).

TABLE 3.

Surgical factors

ProcedureValue (range)
Operative level
 Cervical
  Decompression*21
  Instrumentation surgery11
 Thoracic
  Decompression3
  Instrumentation surgery3
  BKP3
 Thoracolumbar–lumbosacral
  Decompression*84
  Instrumentation surgery118
  BKP29
Mean op time, mins119.8 (25–678)
Mean no. of spinal levels treated1.87 (0–9)
Mean EBL, ml146.2 (0–1160)
Unless otherwise specified, values represent number of patients.

Two patients underwent cervical and thoracolumbar decompression simultaneously.

Perioperative Complications

The rate of all perioperative complications was 20.0% (67 complications were observed in 54 of 270 patients [Table 1]). Complications based on the type of procedures are shown in Fig. 2. Surgical site complications were observed in 22 patients (8.1%): specifically, in six (5.7%) of the 106 patients who underwent decompression, 15 (11.4%) of the 132 patients who underwent instrumentation surgery, and one (3.1%) of the 32 patients who underwent BKP. Dural tears were observed in six patients (2.2%), and hematoma and surgical wound disruption in two patients each (0.7%). Surgical site infections were observed in six patients (2.2%): five patients (1.9%) had superficial wound infections and one (0.4%) had a deep infection. Six (4.5%) of the 132 patients who underwent instrumentation surgery experienced complications specific to the instrumentation: three fractures in the lower instrumented vertebra (2.3%), two cases of pedicle screw back-out after surgery (1.5%), and one pedicle fracture (0.8%). An adjacent-level fracture, a complication specific to BKP, was experienced by one (3.1%) of the 32 patients who underwent that procedure. Repeated operations were required in 11 patients (4.1%).

FIG. 2.
FIG. 2.

Pie chart demonstrating perioperative complications based on the type of operative procedure. Anemia and delirium were observed in all procedures.

No patient experienced major systemic complications, which would include acute coronary syndrome, cardiac failure, cerebrovascular disease, pneumonia, venous thrombosis, renal failure requiring dialysis, peptic ulcer, ileus, cholangitis, or cholecystitis. There were no perioperative deaths in this series.

Minor systemic complications developed in 40 patients (14.8%): seven of the 106 patients who underwent decompression, 31 of the 132 patients who underwent instrumentation surgery, and two of the 32 patients who underwent BKP. These complications included anemia requiring transfusion in 20 patients (7.4%), delirium in 17 patients (6.3%), and urinary tract infection (UTI) in seven patients (2.6%). With regard to patient age, minor systemic complications were observed in 32 (16.1%) of the 199 patients who were 80–84 years of age, six (10.3%) of the 58 patients who were 85–89 years of age, and two (15.4%) of the 13 patients who were in their 90s.

Preoperative Health Status

Patient demographics and preoperative health status are shown in Table 4. Assessments of preoperative general health status showed that the majority of patients were in good condition. The CCI was less than 5 in 242 cases, the ASA-PS was class II in 248 cases, and the ECOG-PS grade was less than 3 in 184 cases. The prevalence of sarcopenia was 24.4% (60/246 patients; there was insufficient data in 24 patients and, hence, those patients could not be assessed for sarcopenia). The GNRI in 203 patients was higher than 98, which means absence of nutritional risk.

TABLE 4.

Demographics and preoperative health status

ItemValue (range)
Demographics
 Age, yrs83.2 (80–99)
 Sex, M/F109/161
 Body mass index, kg/m223.7 (14.4–37)
Preop health status
 CCI score
  022
  162
  256
  357
  445
  516
  68
  73
  81
 ASA-PS class
  II248
  III22
 ECOG-PS grade
  04
  1102
  278
  372
  414
 Sarcopenia*
  Present60
  Absent186
 GNRI score
  >98 (no risk)203
  92 to ≤98 (low risk)36
  82 to <92 (moderate risk)25
  <82 (major risk)6
Unless otherwise specified, values represent number of patients.

Data in 24 patients were insufficient, and thus those patients could not be assessed for sarcopenia.

Statistical Analyses

The univariate analysis showed that the ECOG-PS (p = 0.011) and nutritional risk (p = 0.010) were significantly associated with minor systemic complications. Patient age (p = 0.556), CCI (p = 0.169), ASA-PS (p = 0.094), and the presence of sarcopenia (p = 0.125) were not deemed risk factors. Instrumentation surgery, operation time longer than 180 minutes, three or more operative spinal levels, and an EBL greater than 500 ml were also associated with minor systemic complications (p < 0.0001, < 0.0001, 0.005, and 0.001, respectively). The stepwise multiple regression selected the ECOG-PS, instrumentation surgery, operation time longer than 180 minutes, and three or more spinal levels treated as explanatory variables. In the multivariate logistic regression, ECOG-PS (unit odds ratio [OR] 1.6, 95% confidence interval [CI] 1.106–2.385, p = 0.013), instrumentation surgery (OR 2.9, 95% CI 1.148–7.235, p = 0.024), and operation time longer than 180 minutes (OR 2.9, 95% CI 1.220–7.009, p = 0.016) were significantly associated with minor systemic complications. The details of the statistical analysis are shown in Table 5.

TABLE 5.

Statistical analysis of risk for minor systemic complications

Variablep Value
Univariate analysis
 Patient age0.556
 CCI0.169
 ASA-PS0.094
 ECOG-PS0.011
 Sarcopenia0.125
 Nutritional risk0.010
 Instrumentation surgery<0.0001
 Op time >180 mins<0.0001
 No. of spinal levels treated ≥30.005
 EBL >500 ml0.001
Multivariate analysis
 ECOG-PS0.013 (unit OR = 1.6)
 Instrumentation surgery0.024 (OR = 2.9)
 Op time >180 mins0.016 (OR = 2.9)
 No. of spinal levels treated ≥30.166
Boldface type indicates statistical significance at p < 0.05.

In patients with lower ADL scores (ECOG-PS grades 2, 3, and 4) the rate of minor systemic complications was 18.9% (31/164), whereas in those with higher ADL scores (ECOG-PS grades 0 and 1), the rate was 8.5% (9/106). The rate of complications in patients who underwent instrumentation surgery was 23.5% (31/132); in patients who underwent posterior decompression or BKP, the rate was 6.5% (9/138). Similarly, the rate of complications was 37.0% (20/54) in patients in whom there was a longer operation time and 9.3% (20/216) in patients whose surgery lasted a shorter time. The complication rate in patients with a nutritional risk of “no” or “low” was 12.1% (29/239) and the rate in those with a nutritional risk of “moderate” or “major” was 35.5% (11/31).

Discussion

Although several studies have been published on perioperative complications of spine surgery in the elderly, there have been limited studies that focused on patients 80 years of age or older. Moreover, those studies focusing on that age group have been retrospective studies with small sample sizes21,24,28,29,34 or large sample sizes based on databases lacking in patients’ individual factors.18,26 Kobayashi et al. conducted a multicenter retrospective study of 262 spine surgeries performed in patients 80 years of age or older and identified a high complication rate (29%).16 Nasser and colleagues found a higher complication rate associated with spine surgery in prospective studies than in retrospective studies.22 To the best of our knowledge, a multicenter prospective all-case investigation of perioperative complications of spine surgery in patients 80 years of age or older has not previously been conducted, and the results of our current study are potentially able to determine the perioperative complications of spine surgery.

The majority of previous studies have shown high rates of perioperative complications in patients 80 years or older, ranging from 18.9% to 35%.16,18,21,24,28,34 The complication rate of overall spine surgery was reported to be 16.4%.22 In the current study, we have also demonstrated a higher complication rate of 20.0%; however, we did not observe any major systemic complications in our study.

Earlier studies revealed several risk factors for perioperative complications associated with spine surgery in patients 80 years of age or older. In addition, age older than 85 years, EBL greater than 500 ml, and operation time longer than 180 minutes are considered risk factors.16,34 On the contrary, the association between patients’ preoperative general health status and perioperative complications remains unclear. In patients 85 years or older, Li et al. demonstrated that complications are more likely to occur in patients with three or more comorbidities than in patients with no comorbidities (18.9% vs 14.7%).18 Wang et al. reported that the CCI and ASA-PS, which reflect a patient’s comorbidities and general condition, were not associated with complications.34 In our current study, we reviewed both CCI and ASA-PS scores and found no association between those scores and perioperative complications. Our result is consistent with that of Wang’s study.

Several studies have been performed to examine the association between frailty, sarcopenia, or nutrition status and perioperative complications.1,5,27,35 Zakaria et al. showed that patients with frailty or sarcopenia are more likely to develop postoperative complications (OR 1.70).35 Bokshan et al. demonstrated that patients with sarcopenia have a high incidence of postoperative complications.1 However, Charest-Morin and colleagues found that frailty or sarcopenia did not predict the occurrence of postoperative complications in elderly patients older than 65 years of age.5 Puvanesarajah et al. demonstrated an association between postoperative complications and preoperative malnutrition, which contributed to frailty or sarcopenia. Those authors reported that malnutrition significantly increased the complication rate for the first 90 days postoperatively (OR 4.24) as well as the mortality rate as of the 1-year follow-up (OR 6.16).27 These findings on the effect of frailty, sarcopenia, or malnutrition on the occurrence of perioperative complications were not specific to patients 80 years of age or older. Furthermore, in the current study we showed that both sarcopenia and malnutrition were considered insignificant risk factors for perioperative complications, which is consistent with the result found by Charest-Morin and colleagues. Complication rates in patients with a nutritional risk of “no” or “low” were 12.1%, and those in patients with a nutrition risk of “moderate” or “major” were 35.5%. Our results suggest that nutritional counseling may not be required, especially for patients with lower nutritional risks.

The ECOG-PS is a simple index of ADLs, but it is rarely used to assess ADLs in patients without cancer who require spine surgery. This investigation revealed that a low grade in the ECOG-PS was considered a significant risk factor of perioperative minor complications. Hence, the ECOG-PS should be assessed before surgery in the future.

There have been few articles that mention an association between the type of spinal procedure undertaken and perioperative complications in patients older than 80 years of age. Onda et al. demonstrated no difference in the perioperative complication rate between patients older than 85 years of age who underwent decompression only and patients of similar ages who underwent instrumentation surgery (21.0% vs 28.5%, p = 0.374).24 Puvanesarajah et al. demonstrated that longer spinal fusions were associated with increased rates of complications: patients who underwent fusions extending over more than eight spinal levels had a significantly higher chance of developing perioperative complications.25 In the current study, instrumentation surgery was significantly associated with minor perioperative complications. Spine surgeries for the elderly are generally safe, but surgeons should pay careful attention when instrumentation surgery is involved.

Regarding the types of complications, anemia requiring transfusion, delirium, and a UTI were likely to develop, which is consistent with the findings of previous studies.16,21,26 Fineberg et al. revealed that older patient age (≥ 65 years old), alcohol/drug abuse, depression, psychotic disorders, neurological disorders, iron deficiency anemia, fluid/electrolyte disorders, and weight loss are risk factors for delirium.11 Kobayashi et al. identified that cervical lesion surgery and an EBL greater than 300 ml were significantly associated with postoperative delirium in patients 80 years or older.17 Surgeons should pay careful attention when performing surgery in elderly patients who cannot accept a transfusion due to religious reasons and in patients with risk factors for postoperative delirium.

In the current study we observed perioperative complications in 20.0% of patients, surgical site complications in 8.1%, and minor systemic complications in 14.8% of patients, but no major systemic complications. We also found a low reoperation rate of 4.1%, and no perioperative deaths. The ECOG-PS, instrumentation surgery, and an operation time longer than 180 minutes were considered significant risk factors of minor systemic complications. A one-grade increase in the ECOG-PS resulted in a 1.6-fold risk of developing minor systemic complications. In patients with lower ADL scores (ECOG-PS grades 2, 3, and 4), the rate of minor systemic complications was 18.9%; the rate was half as much, 8.5%, in patients with higher ADL scores (ECOG-PS grades 0 and 1). Instrumentation surgery and an operation time exceeding 180 minutes were both 2.9 times more likely to cause the development of minor systemic complications. The complication rate was 23.5% in patients who underwent instrumentation surgery and 6.5% in those who underwent posterior decompression or BKP. Similarly, the complication rate was 37.0% in patients whose surgeries exceeded 180 minutes and 9.3% in patients whose surgeries took less time. Surgeons should recognize these factors as risks of minor systemic complications such as anemia, delirium, or a UTI. Although decreased daily activity, instrumentation surgery, and longer operation time were recognized as risk factors of perioperative minor systemic complications, older age, comorbidity, and a poor nutrition condition were not considered risk factors. More importantly, no severe complications were observed in our study; hence, spine surgery for elderly patients can be safely performed. Galiano et al.12 and Liao and colleagues19 reported good long-term outcomes of spine surgery in patients 80 years of age or older. Nanjo et al. identified similar benefits and risks of decompression surgery for lumbar spinal stenosis between patients older than 80 years and those younger than 80 years.21 Therefore, surgeons should not be reluctant to perform spine surgery on the basis of the advanced age of the patient.

The current study has several limitations that must be addressed. Clinical outcomes were not evaluated. The 30-day follow-up period was insufficient to assess long-term complications such as pseudarthrosis or adjacent segment disease. However, the current study aimed to determine the perioperative complications of spine surgery for elderly patients, not to verify the efficacy or long-term results of spine surgery. In elderly patients, long-term follow-up may not be beneficial and may lead to difficulty in distinguishing surgery-related complications from increasing age–related pathologies.

Despite these limitations, this is a prospective multicenter cohort study including a relatively large number of patients, and the findings provide important estimates about the safety of spine surgery.

Conclusions

We conducted a multicenter prospective cohort study of perioperative complications in spine surgery for patients aged 80 years or older. Perioperative complications were observed in 20.0%, surgical site complications in 8.1%, and minor systemic complications in 14.8% of patients; no major systemic complications were observed. Although lower ADLs before surgery, instrumentation surgery, and longer operation time were considered significant risk factors for minor systemic complications, spine surgery can be performed safely, even in elderly patients.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: Watanabe, Kanayama, Takahata. Acquisition of data: Watanabe, Takahata, Oda, Suda, Abe, Okumura, Hojo. Analysis and interpretation of data: Watanabe. Drafting the article: Watanabe. Critically revising the article: Kanayama. Reviewed submitted version of manuscript: Kanayama, Takahata. Approved the final version of the manuscript on behalf of all authors: Watanabe. Study supervision: Iwasaki.

Previous Presentations

Portions of this work were presented in poster form at the American Association of Orthopaedic Surgeons 2019 Annual Meeting, Las Vegas, Nevada, March 12–16, 2019.

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    • Export Citation
  • 2

    Bouillanne OMorineau GDupont CCoulombel IVincent JPNicolis I: Geriatric Nutritional Risk Index: a new index for evaluating at-risk elderly medical patients. Am J Clin Nutr 82:7777832005

    • Search Google Scholar
    • Export Citation
  • 3

    Carreon LYPuno RMDimar JR IIGlassman SDJohnson JR: Perioperative complications of posterior lumbar decompression and arthrodesis in older adults. J Bone Joint Surg Am 85:2089–20922003

    • Search Google Scholar
    • Export Citation
  • 4

    Cassinelli EHEubanks JVogt MFurey CYoo JBohlman HH: Risk factors for the development of perioperative complications in elderly patients undergoing lumbar decompression and arthrodesis for spinal stenosis: an analysis of 166 patients. Spine (Phila Pa 1976) 32:2302352007

    • Search Google Scholar
    • Export Citation
  • 5

    Charest-Morin RStreet JZhang HRoughead TAilon TBoyd M: Frailty and sarcopenia do not predict adverse events in an elderly population undergoing non-complex primary elective surgery for degenerative conditions of the lumbar spine. Spine J 18:2452542018

    • Search Google Scholar
    • Export Citation
  • 6

    Charlson MEPompei PAles KLMacKenzie CR: A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis 40:3733831987

    • Search Google Scholar
    • Export Citation
  • 7

    Cruz-Jentoft AJBaeyens JPBauer JMBoirie YCederholm TLandi F: Sarcopenia: European consensus on definition and diagnosis: report of the European Working Group on sarcopenia in older people. Age Ageing 39:4124232010

    • Search Google Scholar
    • Export Citation
  • 8

    Devin CJChotai SParker SLTetreault LFehlings MGMcGirt MJ: A cost-utility analysis of lumbar decompression with and without fusion for degenerative spine disease in the elderly. Neurosurgery 77 (Suppl 4):S116S1242015

    • Search Google Scholar
    • Export Citation
  • 9

    Doyle DJGarmon EH: American Society of Anesthesiologists Classification (ASA Class) in StatPearls. Treasure Island, FL: StatPearls Publishing2018

    • Search Google Scholar
    • Export Citation
  • 10

    Fehlings MGTetreault LNater AChoma THarrop JMroz T: The aging of the global population: the changing epidemiology of disease and spinal disorders. Neurosurgery 77 (Suppl 4):S1S52015

    • Search Google Scholar
    • Export Citation
  • 11

    Fineberg SJNandyala SVMarquez-Lara AOglesby MPatel AASingh K: Incidence and risk factors for postoperative delirium after lumbar spine surgery. Spine (Phila Pa 1976) 38:179017962013

    • Search Google Scholar
    • Export Citation
  • 12

    Galiano KObwegeser AAGabl MVBauer RTwerdy K: Long-term outcome of laminectomy for spinal stenosis in octogenarians. Spine (Phila Pa 1976) 30:3323352005

    • Search Google Scholar
    • Export Citation
  • 13

    Hamel MBHenderson WGKhuri SFDaley J: Surgical outcomes for patients aged 80 and older: morbidity and mortality from major noncardiac surgery. J Am Geriatr Soc 53:4244292005

    • Search Google Scholar
    • Export Citation
  • 14

    Imagama SKawakami NTsuji TOhara TMatsubara YKanemura T: Perioperative complications and adverse events after lumbar spinal surgery: evaluation of 1012 operations at a single center. J Orthop Sci 16:5105152011

    • Search Google Scholar
    • Export Citation
  • 15

    Imajo YTaguchi TYone KOkawa AOtani KOgata T: Japanese 2011 nationwide survey on complications from spine surgery. J Orthop Sci 20:38542015

    • Search Google Scholar
    • Export Citation
  • 16

    Kobayashi KImagama SAndo KIshiguro NYamashita MEguchi Y: Complications associated with spine surgery in patients aged 80 years or older: Japan Association of Spine Surgeons with Ambition (JASA) Multicenter Study. Global Spine J 7:6366412017

    • Search Google Scholar
    • Export Citation
  • 17

    Kobayashi KImagama SAndo KIshiguro NYamashita MEguchi Y: Risk factors for delirium after spine surgery in extremely elderly patients aged 80 years or older and review of the literature: Japan Association of Spine Surgeons with Ambition Multicenter Study. Global Spine J 7:5605662017

    • Search Google Scholar
    • Export Citation
  • 18

    Li GPatil CGLad SPHo CTian WBoakye M: Effects of age and comorbidities on complication rates and adverse outcomes after lumbar laminectomy in elderly patients. Spine (Phila Pa 1976) 33:125012552008

    • Search Google Scholar
    • Export Citation
  • 19

    Liao JCChiu PYChen WJChen LHNiu CC: Surgical outcomes after instrumented lumbar surgery in patients of eighty years of age and older. BMC Musculoskelet Disord 17:4022016

    • Search Google Scholar
    • Export Citation
  • 20

    McGirt MJParker SLHilibrand AMummaneni PGlassman SDDevin CJ: Lumbar surgery in the elderly provides significant health benefit in the US health care system: patient-reported outcomes in 4370 patients from the N2QOD registry. Neurosurgery 77 (Suppl 4):S125S1352015

    • Search Google Scholar
    • Export Citation
  • 21

    Nanjo YNagashima HDokai THamamoto YHashiguchi HIshii H: Clinical features and surgical outcomes of lumbar spinal stenosis in patients aged 80 years or older: a multi-center retrospective study. Arch Orthop Trauma Surg 133:124312482013

    • Search Google Scholar
    • Export Citation
  • 22

    Nasser RYadla SMaltenfort MGHarrop JSAnderson DGVaccaro AR: Complications in spine surgery. J Neurosurg Spine 13:1441572010

    • Search Google Scholar
    • Export Citation
  • 23

    Oken MMCreech RHTormey DCHorton JDavis TEMcFadden ET: Toxicity and response criteria of the Eastern Cooperative Oncology Group. Am J Clin Oncol 5:6496551982

    • Search Google Scholar
    • Export Citation
  • 24

    Onda SKanayama MHashimoto TOha FIwata ATanaka M: Peri-operative complications of lumbar spine surgery in patients over eighty five years of age: a retrospective cohort study. Int Orthop 42:108310892018

    • Search Google Scholar
    • Export Citation
  • 25

    Puvanesarajah VCancienne JMWerner BCJain ASingla AShimer AL: Perioperative complications associated with posterolateral spine fusions: a study of elderly Medicare beneficiaries. Spine (Phila Pa 1976) 43:16212018

    • Search Google Scholar
    • Export Citation
  • 26

    Puvanesarajah VJain AHess DEShimer ALShen FHHassanzadeh H: Complications and mortality after lumbar spinal fusion in elderly patients with late stage renal disease. Spine (Phila Pa 1976) 41:E1298E13022016

    • Search Google Scholar
    • Export Citation
  • 27

    Puvanesarajah VJain AKebaish KShaffrey CISciubba DMDe la Garza-Ramos R: Poor nutrition status and lumbar spine fusion surgery in the elderly: readmissions, complications, and mortality. Spine (Phila Pa 1976) 42:9799832017

    • Search Google Scholar
    • Export Citation
  • 28

    Raffo CSLauerman WC: Predicting morbidity and mortality of lumbar spine arthrodesis in patients in their ninth decade. Spine (Phila Pa 1976) 31:991032006

    • Search Google Scholar
    • Export Citation
  • 29

    Rihn JAHilibrand ASZhao WLurie JDVaccaro ARAlbert TJ: Effectiveness of surgery for lumbar stenosis and degenerative spondylolisthesis in the octogenarian population: analysis of the Spine Patient Outcomes Research Trial (SPORT) data. J Bone Joint Surg Am 97:1771852015

    • Search Google Scholar
    • Export Citation
  • 30

    Shamji MFMroz THsu WChutkan N: Management of degenerative lumbar spinal stenosis in the elderly. Neurosurgery 77 (Suppl 4):S68S742015

    • Search Google Scholar
    • Export Citation
  • 31

    Shimokata HAndo F: [Association of daily physical performance with muscle volume and strength.] Nippon Ronen Igakkai Zasshi 49:1951982012 (Japanese)

    • Search Google Scholar
    • Export Citation
  • 32

    United Nations Department of Economic and Social AffairsPopulation Division: World Population Ageing 2015. UN.org (https://www.un.org/en/development/desa/population/publications/ageing/WPA2015_Infochart.asp) [Accessed October 21 2019]

    • Search Google Scholar
    • Export Citation
  • 33

    Wang MYGreen BAShah SVanni SLevi AD: Complications associated with lumbar stenosis surgery in patients older than 75 years of age. Neurosurg Focus 14(2):e72003

    • Search Google Scholar
    • Export Citation
  • 34

    Wang MYWidi GLevi AD: The safety profile of lumbar spinal surgery in elderly patients 85 years and older. Neurosurg Focus 39(4):E32015

    • Search Google Scholar
    • Export Citation
  • 35

    Zakaria HMSchultz LMossa-Basha FGriffith BChang V: Morphometrics as a predictor of perioperative morbidity after lumbar spine surgery. Neurosurg Focus 39(4):E52015

    • Search Google Scholar
    • Export Citation

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Article Information

Contributor Notes

Correspondence Takamasa Watanabe: Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Hokkaido, Japan. penyomasa@gmail.com.INCLUDE WHEN CITING Published online December 17, 2019; DOI: 10.3171/2019.9.SPINE19754.Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.
Headings
Figures
  • View in gallery

    Bar graph demonstrating the patient distribution by age. The y-axis represents the number of patients and the x-axis represents patients’ ages in years.

  • View in gallery

    Pie chart demonstrating perioperative complications based on the type of operative procedure. Anemia and delirium were observed in all procedures.

References
  • 1

    Bokshan SLHan ALDePasse JMEltorai AEMarcaccio SEPalumbo MA: Effect of sarcopenia on postoperative morbidity and mortality after thoracolumbar spine surgery. Orthopedics 39:e1159e11642016

    • Search Google Scholar
    • Export Citation
  • 2

    Bouillanne OMorineau GDupont CCoulombel IVincent JPNicolis I: Geriatric Nutritional Risk Index: a new index for evaluating at-risk elderly medical patients. Am J Clin Nutr 82:7777832005

    • Search Google Scholar
    • Export Citation
  • 3

    Carreon LYPuno RMDimar JR IIGlassman SDJohnson JR: Perioperative complications of posterior lumbar decompression and arthrodesis in older adults. J Bone Joint Surg Am 85:2089–20922003

    • Search Google Scholar
    • Export Citation
  • 4

    Cassinelli EHEubanks JVogt MFurey CYoo JBohlman HH: Risk factors for the development of perioperative complications in elderly patients undergoing lumbar decompression and arthrodesis for spinal stenosis: an analysis of 166 patients. Spine (Phila Pa 1976) 32:2302352007

    • Search Google Scholar
    • Export Citation
  • 5

    Charest-Morin RStreet JZhang HRoughead TAilon TBoyd M: Frailty and sarcopenia do not predict adverse events in an elderly population undergoing non-complex primary elective surgery for degenerative conditions of the lumbar spine. Spine J 18:2452542018

    • Search Google Scholar
    • Export Citation
  • 6

    Charlson MEPompei PAles KLMacKenzie CR: A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis 40:3733831987

    • Search Google Scholar
    • Export Citation
  • 7

    Cruz-Jentoft AJBaeyens JPBauer JMBoirie YCederholm TLandi F: Sarcopenia: European consensus on definition and diagnosis: report of the European Working Group on sarcopenia in older people. Age Ageing 39:4124232010

    • Search Google Scholar
    • Export Citation
  • 8

    Devin CJChotai SParker SLTetreault LFehlings MGMcGirt MJ: A cost-utility analysis of lumbar decompression with and without fusion for degenerative spine disease in the elderly. Neurosurgery 77 (Suppl 4):S116S1242015

    • Search Google Scholar
    • Export Citation
  • 9

    Doyle DJGarmon EH: American Society of Anesthesiologists Classification (ASA Class) in StatPearls. Treasure Island, FL: StatPearls Publishing2018

    • Search Google Scholar
    • Export Citation
  • 10

    Fehlings MGTetreault LNater AChoma THarrop JMroz T: The aging of the global population: the changing epidemiology of disease and spinal disorders. Neurosurgery 77 (Suppl 4):S1S52015

    • Search Google Scholar
    • Export Citation
  • 11

    Fineberg SJNandyala SVMarquez-Lara AOglesby MPatel AASingh K: Incidence and risk factors for postoperative delirium after lumbar spine surgery. Spine (Phila Pa 1976) 38:179017962013

    • Search Google Scholar
    • Export Citation
  • 12

    Galiano KObwegeser AAGabl MVBauer RTwerdy K: Long-term outcome of laminectomy for spinal stenosis in octogenarians. Spine (Phila Pa 1976) 30:3323352005

    • Search Google Scholar
    • Export Citation
  • 13

    Hamel MBHenderson WGKhuri SFDaley J: Surgical outcomes for patients aged 80 and older: morbidity and mortality from major noncardiac surgery. J Am Geriatr Soc 53:4244292005

    • Search Google Scholar
    • Export Citation
  • 14

    Imagama SKawakami NTsuji TOhara TMatsubara YKanemura T: Perioperative complications and adverse events after lumbar spinal surgery: evaluation of 1012 operations at a single center. J Orthop Sci 16:5105152011

    • Search Google Scholar
    • Export Citation
  • 15

    Imajo YTaguchi TYone KOkawa AOtani KOgata T: Japanese 2011 nationwide survey on complications from spine surgery. J Orthop Sci 20:38542015

    • Search Google Scholar
    • Export Citation
  • 16

    Kobayashi KImagama SAndo KIshiguro NYamashita MEguchi Y: Complications associated with spine surgery in patients aged 80 years or older: Japan Association of Spine Surgeons with Ambition (JASA) Multicenter Study. Global Spine J 7:6366412017

    • Search Google Scholar
    • Export Citation
  • 17

    Kobayashi KImagama SAndo KIshiguro NYamashita MEguchi Y: Risk factors for delirium after spine surgery in extremely elderly patients aged 80 years or older and review of the literature: Japan Association of Spine Surgeons with Ambition Multicenter Study. Global Spine J 7:5605662017

    • Search Google Scholar
    • Export Citation
  • 18

    Li GPatil CGLad SPHo CTian WBoakye M: Effects of age and comorbidities on complication rates and adverse outcomes after lumbar laminectomy in elderly patients. Spine (Phila Pa 1976) 33:125012552008

    • Search Google Scholar
    • Export Citation
  • 19

    Liao JCChiu PYChen WJChen LHNiu CC: Surgical outcomes after instrumented lumbar surgery in patients of eighty years of age and older. BMC Musculoskelet Disord 17:4022016

    • Search Google Scholar
    • Export Citation
  • 20

    McGirt MJParker SLHilibrand AMummaneni PGlassman SDDevin CJ: Lumbar surgery in the elderly provides significant health benefit in the US health care system: patient-reported outcomes in 4370 patients from the N2QOD registry. Neurosurgery 77 (Suppl 4):S125S1352015

    • Search Google Scholar
    • Export Citation
  • 21

    Nanjo YNagashima HDokai THamamoto YHashiguchi HIshii H: Clinical features and surgical outcomes of lumbar spinal stenosis in patients aged 80 years or older: a multi-center retrospective study. Arch Orthop Trauma Surg 133:124312482013

    • Search Google Scholar
    • Export Citation
  • 22

    Nasser RYadla SMaltenfort MGHarrop JSAnderson DGVaccaro AR: Complications in spine surgery. J Neurosurg Spine 13:1441572010

    • Search Google Scholar
    • Export Citation
  • 23

    Oken MMCreech RHTormey DCHorton JDavis TEMcFadden ET: Toxicity and response criteria of the Eastern Cooperative Oncology Group. Am J Clin Oncol 5:6496551982

    • Search Google Scholar
    • Export Citation
  • 24

    Onda SKanayama MHashimoto TOha FIwata ATanaka M: Peri-operative complications of lumbar spine surgery in patients over eighty five years of age: a retrospective cohort study. Int Orthop 42:108310892018

    • Search Google Scholar
    • Export Citation
  • 25

    Puvanesarajah VCancienne JMWerner BCJain ASingla AShimer AL: Perioperative complications associated with posterolateral spine fusions: a study of elderly Medicare beneficiaries. Spine (Phila Pa 1976) 43:16212018

    • Search Google Scholar
    • Export Citation
  • 26

    Puvanesarajah VJain AHess DEShimer ALShen FHHassanzadeh H: Complications and mortality after lumbar spinal fusion in elderly patients with late stage renal disease. Spine (Phila Pa 1976) 41:E1298E13022016

    • Search Google Scholar
    • Export Citation
  • 27

    Puvanesarajah VJain AKebaish KShaffrey CISciubba DMDe la Garza-Ramos R: Poor nutrition status and lumbar spine fusion surgery in the elderly: readmissions, complications, and mortality. Spine (Phila Pa 1976) 42:9799832017

    • Search Google Scholar
    • Export Citation
  • 28

    Raffo CSLauerman WC: Predicting morbidity and mortality of lumbar spine arthrodesis in patients in their ninth decade. Spine (Phila Pa 1976) 31:991032006

    • Search Google Scholar
    • Export Citation
  • 29

    Rihn JAHilibrand ASZhao WLurie JDVaccaro ARAlbert TJ: Effectiveness of surgery for lumbar stenosis and degenerative spondylolisthesis in the octogenarian population: analysis of the Spine Patient Outcomes Research Trial (SPORT) data. J Bone Joint Surg Am 97:1771852015

    • Search Google Scholar
    • Export Citation
  • 30

    Shamji MFMroz THsu WChutkan N: Management of degenerative lumbar spinal stenosis in the elderly. Neurosurgery 77 (Suppl 4):S68S742015

    • Search Google Scholar
    • Export Citation
  • 31

    Shimokata HAndo F: [Association of daily physical performance with muscle volume and strength.] Nippon Ronen Igakkai Zasshi 49:1951982012 (Japanese)

    • Search Google Scholar
    • Export Citation
  • 32

    United Nations Department of Economic and Social AffairsPopulation Division: World Population Ageing 2015. UN.org (https://www.un.org/en/development/desa/population/publications/ageing/WPA2015_Infochart.asp) [Accessed October 21 2019]

    • Search Google Scholar
    • Export Citation
  • 33

    Wang MYGreen BAShah SVanni SLevi AD: Complications associated with lumbar stenosis surgery in patients older than 75 years of age. Neurosurg Focus 14(2):e72003

    • Search Google Scholar
    • Export Citation
  • 34

    Wang MYWidi GLevi AD: The safety profile of lumbar spinal surgery in elderly patients 85 years and older. Neurosurg Focus 39(4):E32015

    • Search Google Scholar
    • Export Citation
  • 35

    Zakaria HMSchultz LMossa-Basha FGriffith BChang V: Morphometrics as a predictor of perioperative morbidity after lumbar spine surgery. Neurosurg Focus 39(4):E52015

    • Search Google Scholar
    • Export Citation
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