When Do Complications Occur After Adult Spinal Deformity Surgery?

North American Spine Society 34th Annual Meeting Highlight

Peer Reviewed

Reported complication rates after adult spinal deformity surgery are 10% to 96%, a wide range that is unhelpful to surgeons, patients, institutions, and insurers, Alan H. Daniels, MD, said at the North American Spine Society 34th Annual Meeting in Chicago, IL. Dr. Daniels drilled down on current evidence to discuss risk factors for complications of adult spinal deformity surgery, and how these complications have changed over time with evolving surgical techniques.

surgeons view diagnostic imagingComplications can be associated with poor outcomes and are almost always associated with increased heatlhcare costs. Photo Source: iStock.com.

The wide-ranging complication rate in adult spinal deformity (ASD) surgery results from the various patient, surgeon, procedural, and reporting factors involved, as well as the variable definitions of complications, said Dr. Daniels who is Associate Professor of Orthopaedics at the Warren Alpert Medical School of Brown University, and Chief of Adult Spinal Deformity Service at the Rhode Island Hospital and Miriam Hospital in Providence, RI.

For example, “a patient with a relatively minor thoracolumbar scoliosis has a very low predicted complication rate compared to a patient with a combined cervical-thoracolumbar deformity who also has cervical myelopathy,” Dr. Daniels said. However, he questioned, “does development of minor thigh numbness and quad weakness in a patient who underwent anterior column realignment qualify as a complication?”

“We do know, however, that the complication rate in ASD is among the highest of all surgical subspecialties,” Dr. Daniels noted. “Complications can be associated with poor outcomes and are almost always associated with increased healthcare costs.”

Risk Stratification for Adult Spinal Deformity Complications

In a prospective multicenter study assessing perioperative (<6 weeks) and delayed (>6 weeks) complications at 2 years in adult patients who underwent adult cervical spinal deformity (ACSD), researchers stratified complications into minor and major categories.1 All patients had ≥4 levels fused and had at met at least one of the following criteria at baseline:

  • Scoliosis of ≥20
  • Sagittal vertical axis (SVA) ≥5 cm
  • Pelvic tilt ≥25
  • Thoracic kyphosis ≥60

Overall, nearly 70% of patients had at least one complication, 28% of whom required surgical revision, Dr. Daniels said.1 Complication rates were associated with older age (P=0.009), greater body mass index (P≤0.031), increased comorbidities (P≤0.007), previous spine fusion (P=0.029), and 3-column osteotomies (P=0.036). Two perioperative mortalities occurred: one due to pulmonary embolism and one due to inferior vena cava injury.

Table: Rate of Common Complications in 291 Patients Following ACSDTable: Rate of Common Complications in 291 Patients Following Adult Cervical Spinal Deformity Surgery

When Do ASD Complications Occur?

Data from a multicenter prospective study involving 280 consecutive patients who underwent ASD found a similar complication rate (258 major, 271 minor; total 75%) at a mean follow-up of 2.9 years.2 The rate of complications involving reoperation was 28%, infection 10%, proximal junctional kyphosis 13%, and rod failure 15%. The peak timing of complications varied by subtype.

“All of the complications peaked at the time 0- to 3-month mark, that is the acute perioperative period,” Dr. Daniels said. “The complication rate dropped precipitously at 3 to 6 months, and then slowly increased.”

“The reoperation rate peaked early, and was closely tied to the infection rate,” Dr. Daniels said. “Similarly, neurologic complications occurred early in the first early perioperative period and then decreased after that. In contrast, the proximal junctional kyphosis rate had a bimodal distribution, where it peaked at 3 months, and also at 2 years, which increased the reoperation rate later on.”

“Overall, the message was that infection and neurologic complications peak at less than 3 months,” Dr. Daniels said. “The rate of proximal junctional kyphosis is bimodal and peaks early (<3 months) and later (>1 year). Implant failure peaks late at 1 to 2 years and potentially even later with 4-rod constructs. In addition, a significant correlation was found between preoperative sagittal vertical axis and total complications, major complications, and reoperation. Furthermore, BMI was associated with total complications and implant complications.”

Have Complication Rates Changed Over Time?

“Even in my relatively short career, I have seen major changes in terms of utilization of 3-column osteotomies, 4-rod constructs, and tranexamic acid. Therefore, the complication profile changed alongside those advances. And, it happened very quickly.”

A retrospective review of prospectively collected data from 905 adults undergoing spinal deformity surgery between 2009 to 2016 shows that patient demographics changed over time with a significant increase in the following variables:3

  • Age (52 to 63.1 years; P<0.001)
  • BMI (26.3 to 32.2, P=0.003)
  • Charlson Comorbidity index (1.4 to 2.2; P<0.001)
  • Rate of previous spine surgery (39.8% to 53.1%; P=0.01)
  • Baseline disability—VAS back and leg pain (P<0.01)
  • Oswestry Disability Index
  • 22-item Scoliosis Research Society Questionnaire scores (P<0.001)

“Thus, patients undergoing adult spinal deformity surgery have become older, sicker, more overweight, and more disabled,” Dr. Daniels said.

In addition, the types of procedures performed changed over time with a decrease in 3-column osteotomies (from 36% of 17%), increase in lateral interbody fusions (from 6% to 24%; P=0.004) and a decrease in anterior lumbar interbody fusions (from 22.9% to 16.7%; P=0.043). Transforaminal lumbar interbody fusion/posterior lumbar interbody fusion utilization remained relatively the same.

Use of recombinant human bone morphogenetic protein-2, which Dr. Daniels said is  common in this patient cohort, initially declined from 84% in 2012 to 58% in 2013, and then rebounded back to 76% in 2016. This fluctuation may affect future rates of long-term rod fracture rates, Dr. Daniels noted. Tranexamic acid use increased rapidly from 13% to 50%.

Despite these changes, all radiographic parameters (ie, sagittal vertical axis, pelvic tilt, pelvic incidence-lumbar lordosis, and maximum Cobb angles) were unchanged over the years in a subgroup analysis of 436 patients with a minimum follow-up of 2 years. “Thus, correction is still being achieved, just through different techniques,” Dr. Daniels said.

Notably, the overall complication rate decreased from 73% in 2008-2014 to 63% in 2015 (P=0.03). Decreases were found in both intraoperative (33% to 9%) and perioperative (<30 days) complications (43% to 24%; P=0.03). The infection rate did not change over time (6.7% to 9.7%), but rod fracture rates peaked in 2011 (21%)—which was closely correlated with the 3-column osteotomy rate—and then decreased to no cases in 2016, Dr. Daniels said.

“The message is that over these 7 years, despite an increasingly elderly, medically compromised, and obese patient population, the complication rates decreased suggesting that evolving strategies may really be working,” Dr. Daniels said.


“Complication rates in ASD surgery vary depending on patient, procedure, surgeon, and reported factors,” Dr. Daniels said. “Understanding the peak timing of when these complications happen may help assist in awareness, prevention, and patient counseling. All patients should know that they need to be watched carefully after 2 years and beyond for proximal junctional kyphosis and rod fracture. In addition, the complication rates, just like our techniques, are evolving and should be carefully monitored, reported, and studied.”

Dr. Daniels reports relationships with Stryker, Spineart, Orthofix, Southern Spine, Medtronic, and Springer.

Updated on: 12/20/19
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Preventing Spine Surgeon Burnout and Suicide
Alan H. Daniels, MD
Associate Professor of Orthopaedic Surgery
The Warren Alpert Medical School of Brown University
Providence, RI

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