Adjacent segment disease after anterior cervical discectomy and fusion: Incidence and clinical outcomes of patients requiring anterior versus posterior repeat cervical fusion.
BACKGROUND
Adjacent segment disease (ASD) is a well-recognized long-term outcome in patients with degenerative disease of the spine. In this manuscript, we focus on the development in ASD in patients who have undergone a prior anterior cervical discectomy and fusion (ACDF).


METHODS
Patient data were collected via clinical notes and patient interviews. Patients were followed for an average of 92.4 ± 72.6 months after the index ACDF.


RESULTS
Of the 108 patients who underwent revision surgery due to symptomatic ASD, 77 patients underwent re-do ACDF, while 31 patients had posterior fusion surgery. Patients were more likely to be operated on posteriorly if they were older (P = 0.0115), male (P = 0.006), or had a higher number of cervical vertebral segments fused during the index ACDF (P = 0.013). These patients were statistically also more likely to exhibit myelopathic symptoms (P = 0.0053), and usually had worse neurologic function as assessed on the Nurick (P = 0.0005) and ASIA scales (P = 0.0020). Postoperatively, patients receiving anterior revision surgeries had higher rates of recurrent radiculopathy (P = 0.0425) and higher recurrence of ASD compared with patients fused posteriorly (P < 0.0001).


CONCLUSIONS
Patients undergoing an anterior revision surgery for ASD after ACDF have higher rates of postoperative radiculopathy and redevelopment of ASD when compared with posteriorly approached patients. Patients receiving posterior revision surgery had higher intraoperative blood loss, hospitalizations, and postoperative complications such as wound infections and discharge to rehabilitation, but had a statistically lower chance of redevelopment of ASD requiring secondary revision surgery. This may be due to the fact that posterior revision surgeries involved more levels fused. This study provides one of the longest and most comprehensive follow-ups of this challenging patient population. Prospective studies comparing surgical approaches and techniques are needed to corroborate our findings.
Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA ; Johns Hopkins Biomechanics and Surgical Outcomes Laboratory, Baltimore, MD, USA.
Mohamad
M
Bydon
Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA ; Johns Hopkins Biomechanics and Surgical Outcomes Laboratory, Baltimore, MD, USA ; Medical Scientist Training Program, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Risheng
R
Xu
Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA ; Johns Hopkins Biomechanics and Surgical Outcomes Laboratory, Baltimore, MD, USA.
Rafael
R
De la Garza-Ramos
Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA ; Johns Hopkins Biomechanics and Surgical Outcomes Laboratory, Baltimore, MD, USA.
Mohamed
M
Macki
Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA ; Johns Hopkins Biomechanics and Surgical Outcomes Laboratory, Baltimore, MD, USA.
Daniel M
DM
Sciubba
Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA ; Johns Hopkins Biomechanics and Surgical Outcomes Laboratory, Baltimore, MD, USA.
Jean-Paul
JP
Wolinsky
Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA ; Johns Hopkins Biomechanics and Surgical Outcomes Laboratory, Baltimore, MD, USA.
Timothy F
TF
Witham
Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA ; Johns Hopkins Biomechanics and Surgical Outcomes Laboratory, Baltimore, MD, USA.
Ziya L
ZL
Gokaslan
Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA ; Johns Hopkins Biomechanics and Surgical Outcomes Laboratory, Baltimore, MD, USA.
Ali
A
Bydon
Adjacent level disease; adjacent segment disease; anterior cervical discectomy and fusion; cervical; spine