by Elizabeth Hofheinz, M.P.H., M.Ed.
Some patients who undergo anterior cervical discectomy and fusion (ACDF) don’t have enough symptoms to merit undergoing radiographs. This is one of the reasons that we have no accurate prevalence when it comes to nonunion following ACDF. Now, researchers from multiple centers have waded into this arena in order to obtain more precise information. Their work, “Asymptomatic ACDF Nonunions Underestimate the True Prevalence of Radiographic Pseudarthrosis,” appears in the July 1, 2020 edition of Spine.
Charles Crawford III, M.D. is an orthopedic surgeon at the Norton Leatherman Spine Center in Louisville, Kentucky, and is an assistant professor in the Department of Orthopaedic Surgery at the University of Louisville School of Medicine. A co-author on the study, Dr. Crawford commented to OSN, “While ACDF surgeries performed with allograft and a plate are frequently associated with excellent patient outcomes, there is disagreement about the clinical significance and rate of non-unions. Non-unions occur when the bone does not fully heal, but they are not always symptomatic. On the other hand, some ACDF nonunions do appear to be symptomatic and are a common reason why a patient may undergo a second surgery.”
“We had the opportunity to use an excellent data source (data that had been meticulously collected as part of FDA IDE studies) to attempt to accurately clarify some of these issues.”
Using participants in the ACDF arm of the Medtronic IDE trials for cervical disc arthroplasty (CDA), the researchers performed a secondary analysis in order to compare patient-reported outcomes in patients with nonunion to those with a solid fusion. A total of 345 participants who were enrolled in the control arm of IDE trials for CDA who had single-level ACDF with allograft and plate with 24-month data were the study cohort.
The authors wrote, “Using the 24-month postop evaluation, subjects were divided into those who had radiographic fusion and those who did not using strict study criteria. SF-36, NDI, Neck and Arm pain NRS scores were reported at 12, 24, 36, 60, and 84 months postop. For subjects who had secondary surgery failures, the last observations before the secondary surgery were carried forward to future visits for the analysis.”
Dr. Crawford told OSN, “The radiographic non-union rate at 24-month follow-up was 13%. Group averages for patient reported outcomes at 24 months were similar between patients who had a non-union and patients who were solidly fused (i.e. many of the radiographic non-unions were asymptomatic). Patients who had a radiographic non-union were 3 times as likely (21% vs. 7%) to undergo a second surgery that involved the index level which suggests that a minority, yet important, percentage of patients did have a symptomatic nonunion.”
Citing his “take home” points, Dr. Crawford added, “ACDF with allograft and plate has a 13% non-union rate. We should find ways to lower this rate with better surgical techniques, patient optimization, and new technologies. Also, many ACDF non-unions are asymptomatic or minimally symptomatic, so it’s best to just follow the patient and only offer additional surgery if the patient develops sufficient symptoms.”