Korean society is undergoing progressive aging, with the number of individuals aged over 85 years having reached 930,000 by 2022, constituting 1.8% of the total population. This figure marks a 1.7-fold increase from 7 years ago, a 4.8-fold increase from 2 decades ago, and a 6.2-fold increase from 3 decades ago. Additionally, 152,000 individuals are over 90, comprising 0.3% of the population.

The confluence of an aging society and recent advancements in surgical techniques and anesthesia have led to a heightened demand for spinal surgery among elderly patients, with a corresponding rise in procedures aimed at improving quality of life. The incidence of surgical complications and mortality rates exhibited an increasing pattern among the elderly demographic. Therefore, the preoperative assessment of these patients is of paramount significance, and the presence of concurrent medical conditions and diminished physiological resilience have been established as contributing factors to unfavorable outcomes in these patients^2,11,20). Preoperative assessments of pulmonary, renal, and cardiac function offer predictive insight into postoperative complications associated with these organ systems among elderly patients^14,18,23,26).

Given the rising demand for spinal surgery among the elderly, it is imperative to undertake clinical studies with long-term follow-up. These studies aim to evaluate the optimal approaches to managing surgical complications and devising strategies to mitigate these adverse outcomes. Studies have documented perioperative complications in elderly patients, typically categorizing the term “elderly” as those with a chronological age of 65. In contrast, only a limited number of comparable investigations exist for the very elderly, often referring to individuals over 75 years, and none have exclusively concentrated on patients aged 85 years or above. To address this gap, we aimed to conduct a retrospective analysis of a prospective surgical database encompassing surgical particulars and perioperative complications associated with spine surgery in individuals aged 85 years or older and examine the incidence and severity of complications, patient and surgical variables, and pre- and postoperative ambulatory function^1,3,17,21).

We conducted a retrospective analysis of degenerative spine surgeries on patients aged 85 years and above by two spinal neurosurgeons at a solitary tertiary academic medical center between October 2015 and January 2023. The study encompassed 36 consecutive patients (21 men and 15 women) with a mean age of 87 ± 2.2 (range, 85-92) years.

We included patients who were followed up for over one-year post-surgery and excluded individuals with spinal conditions other than degenerative diseases. Patient assessments involved the acquisition of standing upright flexion/extension radiographs, computed tomography scans, and magnetic resonance imaging scans. Subsequently, clinical symptoms were correlated with these diagnostic findings to ascertain the necessity and scope of surgical intervention.

Surgical candidates included patients in whom conservative treatment was ineffective. These included individuals who had undergone physical therapy, received injections or pursued medical management without success. Additionally, patients who presented with neurological deficits consistent with the findings of physical examinations were considered surgical candidates.

All patients exhibited considerable pain and disability stemming from conditions such as radiculopathy, neurogenic claudication, axial pain due to lumbar degeneration, or mechanical instability. The American Society of Anesthesiologists (ASA) Physical Status classification (http://www.asahq.org/resources/clinical-information/asa-physical-status-classification-system) was employed, where Class I denotes a patient in a normal, healthy condition; Class II, with mild systemic disease; Class III, severe systemic disease; Class IV, severe systemic disease posing a constant life-threatening risk; Class V, moribund patient whose survival is improbable without surgery; and Class VI, patient is brain-dead and is undergoing organ retrieval for transplantation purposes.

All patients who underwent surgical treatment received preoperative clearance from their primary medical physician as well as from a cardiologist and any other medical specialist. Perioperative complications were retrospectively identified through a chart review. Complications were categorized based on the affected system (neurological-spine, neurological-central, wound, integumentary, cardiac, pulmonary, renal function, hematologic, thrombotic, skeletal, and mortality) as well as temporal duration (temporary vs. permanent).

Surgical procedures involving the thoracic spine and posterior spinal fusion (PSF) were classified as fusion surgery. In contrast, procedures involving lumbar disc excision, decompression, and anterior cervical discectomy and fusion were categorized as minimal interventions.

Ambulatory function was assessed using a four-point scale as follows: 4, independent ambulation; 3, need for a cane; 2, reliance on a walker; and 1, wheelchair-bound. Patient age, operative time, the ASA of Anesthesiologists class, number of treated levels, and incorporation of fusion were investigated as possible predictive factors. These evaluations were conducted through chart reviews rather than by the attending surgeons.

The demographic characteristics of the study population are presented in Table 1. The average age of the patients was 87 ± 2.2 (range, 85-92) years, including 21 males. The average the ASA class was 2.31 ± 0.47, ranging from II to III. Among these cases, 12 surgeries (33%) included fusion procedures, while 24 surgeries fell into the category of minimally invasive interventions (67%).

The mean number of treated levels was 2.06 ± 1.35, ranging from 1 to 6. The mean overall surgical procedure time was 144.0 ± 70.4 (range, 40-365) min. The cohort exhibited improved ambulatory function, as indicated by mean scores progressing from 2.17 ± 0.99 to 3.31 ± 0.63; this signified an average improvement of 1.14 ± 0.73. Among our patients, 13 (36%) showed enhanced ambulatory capability. In addition, mean VAS scores improved from 5.37 ± 1.26 to 3.37 ± 0.97.

A total of 22 complications occurred in 20 patients (Table 2). Notably, one patient with weakness did not improve postoperatively, although neurological deterioration did not occur because of complications due to a problem with the central nervous system. The recorded instances included 10 cases of delirium, four of renal dysfunction, three of pulmonary complications, two of falls, one of infection, and one of fatality. Of these, 19 cases were temporary in nature, whereas one case was permanent (death).

All three instances of pulmonary complications involved postoperative pneumonia, with one case progressing to sepsis and eventual fatality. Among the four reported cases of electrolyte abnormalities, two individuals encountered postoperative hyponatremia, while the remaining two exhibited transient electrolyte imbalances attributable to acute kidney injury. Furthermore, one case of postoperative infection demonstrated improvement following antibiotic treatment.

Twenty-two complications occurred in 20 of our patients, 19 of which were temporary, and one permanent. Patient age, operation time, the ASA of Anesthesiologists class, number of treated patients, and minimally invasive surgery were not significantly associated with complications.

Degenerative spinal disease is a significant problem for many patients, and most seek non-surgical treatment¹⁰⁾. Many surgical treatment strategies exist, and the type of surgery required is patient-specific. However, surgical options for elderly patients are limited by medical comorbidities, ability to tolerate a long operation, and life expectancy. Interestingly, elderly patients have been shown to benefit significantly from surgery in terms of symptom improvement²⁵⁾.

Elderly patients older than 65 years have major postoperative complications at rates of 3% to 29%^{3,4,6,8,13,15,21)} and the risk factors for these complications include increased age, comorbidities, blood loss, operative time, and a number of levels^6,12,27). Studies in the very elderly, which generally indicate patients aged 80 years, have shown complication rates of 20%, with a length of intensive care unit stay as a risk factor, and 26% without mortality in lumbar decompression surgery, which was concluded to be safe and effective^5,9,24). In a previous multicenter study in Japan, Kobayashi et al.¹⁶⁾ found a perioperative complication occurred in 54% of cases, with 23% major complications. Takahashi et al.²⁵⁾ describe a morbidity rate of 10.4% in more than 30,000 spinal surgeries in patients of all ages. Therefore, elderly patients are at higher risk of complications after spinal surgery.

However, Drazin et al.⁸⁾ reported 38 complications and 1% morbidity in relatively older patients (mean age, 74.2), which generally resulted in favorable outcomes with low mortality after surgery for adult spinal deformity. Additionally, Wang et al.²⁸⁾ reported a 19.2% complication rate from lumbar spinal surgery in elderly patients aged 85. Consequently, surgical outcomes in elderly patients are still considered inconsistent.

Delirium was the most common postoperative complication in this study. Previous studies have also reported that postoperative delirium commonly occurs in elderly patients and is associated with a significant increase in mortality-related complications such as cerebrovascular disease, length of hospital stay, and admission to a long care facility^25-27). Postoperative delirium is characterized by acute onset with fluctuations in neuropsychiatric function, inattention, disorganized thinking, and altered levels of consciousness²⁸⁾. Delirium may also lead to fractures due to falls and discontinuous treatment due to intravenous drip removal. In this study, delirium occurred at a rate of 28%, consistent with previous reports¹⁹⁾.

Pulmonary complications are common and have been reported to be as high as 64%¹⁴⁾. The rate of deep vein thrombosis has been shown to vary depending on the surgical approach. Dearborn et al.⁷⁾ reported deep vein thrombosis rates of 6% for anteroposterior fusions and 0.5% for posterior fusions; Rokito et al.²²⁾ found the rate to be 0.3% in 329 patients undergoing spinal fusion, whereas West and Anderson²⁹⁾ found it to be 14% in 41 patients undergoing PSF. Our second most common complication was pulmonary fibrosis and, unlike previous studies, was pneumonia our most common pulmonary complication.

Spinal surgery aimed at addressing lumbar degenerative diseases can be considered a viable option for extremely elderly patients. Although the incidence of complications tends to be higher in younger patients, it can still be deemed acceptable when weighed against the potential advantages of the intervention. The key to achieving favorable outcomes is meticulous consideration of each patient’s underlying medical conditions, with a critical focus on minimizing both anesthetic and operative times. By taking a cautious approach to these factors, the surgical approach can be optimized for the elderly population, ultimately contributing to the success and safety of the procedure.

This study had some limitations. First, a restricted sample size; and second, the absence of a contemporaneous comparator group comprising either younger patients or patients of the same age treated conservatively. Accumulating a substantial number of patients in this particular age category poses challenges, and registries or multi-institutional databases frequently lack the detailed data required for a comprehensive analysis of specific variables and outcomes. Moreover, it is important to note that this study did not include patients aged >85 years who declined the surgery. Further large-scale, multicenter studies are warranted.

The increasingly aging population in Korea has resulted in a growing demand for spinal surgery among elderly patients seeking to enhance their quality of life. This study sheds light on the challenges and outcomes associated with spine surgery in individuals aged 85. Our findings highlight the relatively low risk and prevalence of complications such as delirium and pulmonary issues, along with the need for thorough preoperative assessments in this age group.