What are the risk factors for pseudarthrosis in long segment spinal fusions? What is the role of anterior stability? A multinational team of researchers dove into these questions lately with their study, “Pseudarthrosis in adult spine deformity surgery: risk factors and treatment options,” which was published in the May 5, 2021, edition of European Spine Journal.
Surgical Technique Drives Pseudarthrosis: New Study
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#adultspinedeformity#pseudarthrosis#longsegmentspinalfusion
David Kieser, M.B.Ch.B., Ph.D. is an orthopedic surgeon at the University of Otago in Christchurch, New Zealand, and was a co-author on this retrospective review. While this has been studied previously, stated Dr. Kieser to OTW, it has only been examined in small series and without combining patient risk factors, surgical techniques, and radiological parameters.
Using data from six spine centers and 524 patients diagnosed with adult spine deformity who had been treated with ≥ 4 fused levels with a minimum follow-up of ≥ 2 years. The team gathered full body X-rays preop, <3 months and ≥ 2 years and documented Oswestry Disability Index (ODI), Scoliosis Research Society-22 (SRS-22) and the Short Form Survey (SF36) scores both pre- and post-operatively.
The investigators also collected data regarding each patient’s age, gender, body mass index, smoking status, comorbidities and any prior spine fusion procedures. In addition, they collected data for variables related to surgery including blood loss, surgical time, approach (anterior, posterior, combined), type of osteotomies performed, interbody cages, number of levels fused, the level of the most proximal and most distal fusion, rod material used, rod diameter and revision surgery.
Of all patients, 65 (12.4%) developed pseudarthrosis and 53 underwent revision surgery. “Notably, 88% of pseudarthrosis cases are associated with fusion length, osteotomy requirement, pelvic fixation and combined approaches,” wrote the authors. “Sagittal alignment is not related to the rate of pseudarthrosis. Health related and quality of life scores were comparable at last FU [follow-up] between patients revised for pseudarthrosis and those that did not require revision surgery (ODI = 28% no revision and 30% revision group).
“Pseudarthrosis,” said Dr. Kieser to OTW, “is not related to malalignment, but with the surgical techniques employed for its treatment. Anterior approaches with anterior support decrease the rate by 30%, while long fusions, osteotomies and pelvic fixation increase its rate.”
“The surgical technique is the most important determinant and surgeons should consider this when determining the optimal surgical plan.”
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This is a fascinating development. In my practice we've seen similar outcomes with the revised protocol. The key differentiator seems to be patient selection criteria. Has anyone else noticed the correlation with BMI thresholds?
Great point. I'd push back slightly on the conclusion, the sample size in the cited study is too small to draw population-level inferences. That said, the directional signal is compelling and worth a larger RCT.
We implemented a similar approach last year. Early results are promising but we're still gathering 12-month follow-up data. Happy to share our protocol if anyone is interested.
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