One third of adult spinal deformity patients experience implant-related complication

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Nearly one-third of patients undergoing adult spinal deformity surgery experience a radiographic or implant-related complication, according to a study published ahead-of-print in the journal Spine. Furthermore, just over one-half of these complication patients required a re-operation within two years of surgery, significantly affecting quality of life scores.

The International Spine Study Group conducted this multicentre, prospective review of surgical adult spine deformity patients to assess the incidence, risk factor and impact of radiographic and implant-related complications on health-related quality of life (HRQOL) measures.

HRQOL was measured using the Oswestry Disability Index (ODI), General Health Survey (SF-36), and Scoliosis Research Society (SRS-22r) measures at baseline, six weeks, one year and two years postoperatively. Univariate testing was performed “as appropriate”, and multivariate logistic regression modelling was used to determine independent predictors of implant-related complications. The team analysed 245 patients that met the inclusion criteria.

The Study Group reports that the incidence of implant-related complication was 31.7%, of which 52.6% required reoperation. Rod breakage accounted for 47% of the implant-related complications, and proximal junctional kyphosis accounted for 54.5% of radiographic complications.

Univariate analysis identified the following potential risk factors for implant-related complication: weight, American Society of Anesthesiologists score (ASA), revision, stopping fusion in the lower thoracic spine, worse SRS-Schwab classification modifiers (pelvic tilt, pelvic incidence minus lumbar lordosis, sagittal vertical axis), higher T1 spino-pelvic inclination, and higher T1 slope.

The authors write that independent predictors of complications as identified on multivariate logistic regression included: ASA score (odds ratio 1.75, p=0.029) and sagittal vertical axis modifier (odds ratio 3.43, p=0.0001). The implant-related complications and non-complications groups each experienced significant improvement over time, as measured on the ODI (p=0.0001), SF36 (p=0.0001), and SRS-22r (p=0.0001). However, the rate of improvement over time was less for patients with implant-related complications (SRS-22r p=0.043, SF-36 p=0.0001).

The complications observed in this study, the authors suggest, “significantly affected HRQOL measures”. They suggest that baseline patient characteristics and parameters of the SRS-Schwab classification may be used in future by physicians “to help identify those patients at greater risk” of implant-related complications.

“According to our study,” the authors write, “patients that had more co-morbidities and more significant deformity in the sagittal plane were at greater risk. Identifying risk factors is the first step in the effort to decrease these types of complications”.

“Collectively, these findings emphasise the importance of further studying ways to decrease these types of complications as a means of improving patient outcomes,” the authors conclude.

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