High rate of complications following adult deformity surgery may not ultimately affect outcomes

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Surgical treatment for adult spinal deformity can improve pain and disability, but is associated with a high rate of complications. However, many of these complications “likely have minimal or no impact on ultimate patient outcome,” according to Justin Smith, professor of Neurosurgery at University of Virginia Medical Center, Charlottesville, USA, who presented the findings at EUROSPINE 2015 (2–4 September, Copenhagen, Denmark).

Smith told delegates that there are multiple studies that have shown that surgical treatment “has the potential to improve pain and disability in adults with symptomatic spinal deformity”, despite the high complication rates associated with these procedures. However, most previous studies reporting adult spinal deformity surgery complication rates have been limited by “retrospective designs, single-surgeon or single-centre cohorts, lack of rigorous data collection and/or limited follow-up”, he said.

Smith and colleagues at the International Spine Study Group (ISSG) conducted a multicentre, prospective, observational study of operatively treated adult patients. Patients were included if they were at least 18 years of age and had radiographic evidence of spinal deformity that included at least one of the following: coronal Cobb angle ≥20 degrees, sagittal vertical axis >5cm, pelvic tilt ≥25 degrees or thoracic kyphosis ≥60 degrees. To help ensure a full and accurate data set, the team used standardised data collection forms, onsite study coordinators and regular auditing of the data. Complications were defined as perioperative (≤6 weeks from surgery) or delayed (>6 weeks from surgery) and as minor or major. The study investigated 291 patients with a mean age of 56.2 years. Almost all of the patients underwent a posterior procedure (99%, n=287) while 25.4% (n=74) also underwent an anterior procedure.

Overall there were 270 minor (n=145) and major (n=125) perioperative complications. Of the patients involved, 51.5% (n=150) were affected by one or more of these complications. A total of 199 minor (n=62) and major (n=137) delayed complications were reported, affecting 42.6% (n=124) of patients. In total, 469 minor or major complications were reported across the two-year follow-up, affecting 69.8% (n=203) of patients.

Implant-related complications accounted for 81 minor and major complications (27.8%), the most common of which was rod breakage (n=40). The most common of the 81 (27.8%) radiographic complications was proximal junctional kyphosis, which affected 39 (13.4%) of the 291 patients. New or worsened radiculopathy was the most common neurologic complication (26 out of 81 complications), while deep wound infections were reported in 18 patients as the most common infection-related complication. The most common intraoperative complications were excessive bleeding (11% of patients) and dural tear (10.7% of patients).

Smith noted that “there were many patients who had no complications whatsoever in the two-year follow up, while the rest of the patients had anywhere from one to as many as 10 complications.” Older patients (65–86 years) were more likely to have any kind of complications (78.9%), while in the youngest age group (18–44 years) 55.4% reported any complication. Smith also pointed out that “these differences between age groups were most notable for major complications”.

Factors associated with a greater chance of both perioperative and delayed complications included a greater body mass index, greater Charlson Comorbidity Index and greater ASA score. Patients that had undergone previous spinal fusion were at a greater risk of perioperative complications, while those treated with a three-column osteotomy were at a greater risk of delayed complications.


“An opportunity to improve care”

Smith explained that investigating surgical complications can be seen as “an opportunity to improve care and reduce complications”, citing common complications as the drivers of many surgical advances. For example, in the case of rod fracture, the ISSG and others “have been pioneering efforts to develop techniques for accessory and satellite rods” which have been shown by preliminary studies to decrease rod fracture rates, especially when used in the setting of three-column osteotomies. For proximal junctional kyphosis, tethering techniques and junctional support have been developed to help reduce complications, while the need to address intraoperative blood loss problems has led to the use of tranexamic acid and the challenges of infection have inspired the use of vancomycin powder.

In subsequent studies, the ISSG intends to further investigate risk factors for complications and look at predictive modelling.