Safety analysis and complications of condylar screws in a single-surgeon series of 250 occipitocervical fusions

Sharon Ka Po Tam,Ilene Ruhoy,Paolo A Bolognese,Marat Avshalumov,Andrew Brodbelt,Roger W Kula,Mansoor Foroughi,Denmark Mugutso

doi:10.1007/s00701-021-05039-z

Abstract

ObjectiveCondylar screw fixation is a rescue technique and an alternative to the conventional configuration of occipitocervical fusion. Condylar screws are utilized when previous surgical bone removal along the supraocciput has occurred which makes anchoring of a traditional barplate technically difficult or impossible. However, the challenging dissection of C0-1 necessary for condylar screw fixation and the concerns about possible complications have, thus far, prevented the acquisition of large surgical series utilizing occipital condylar screws. In the largest case series to date, this paper aims to evaluate the safety profile and complications of condylar screw fixation for occipitocervical fusion.MethodsA retrospective safety and complication-based analysis of occipitocervical fusion via condylar screws fixation was performed.ResultsA total of 250 patients underwent occipitocervical fusions using 500 condylar screws between September 2012 and September 2018. No condylar screw pullouts, or vertebral artery impingements were observed in this series. The sacrifice of condylar veins during the dissection at C0-1 did not cause any venous stroke. Hypotrophic condyles were found in 36.4% (91 of the 250) cases and did not prevent the insertion of condylar screws. Two transient hypoglossal deficits occurred at the beginning of this surgical series and were followed by recovery a few months later. Corrective strategies were effective in preventing further hypoglossal injuries.ConclusionsThis surgical series suggests that the use of condylar screws fixation is a relatively safe and reliable option for OC fusion in both adult and pediatric patients. Methodical dissection of anatomical landmarks, intraoperative imaging, and neurophysiologic monitoring allowed the safe execution of the largest series of condylar screws reported to date. Separate contributions will follow in the future to provide details about the long-term clinical outcome of this series.

Highlights

Occipito-cervical (OC) fusions are used to treat a variety of pathologies affecting the craniocervical junction [2, 5, 7, 8, 20].Condylar screws have been recently introduced as a rescue technique for OC fusions, whenever an existing craniectomy, or a fractured or thin supraocciput limit the available fixation points to the occipital squama [1, 21]
Plus one or more of the following radiological criteria: (1) basilar impression or basilar invagination; (2) clivo-axial angle (CXA) of 135° or below, on neutral imaging studies (MRI or 2DCT); (3) pB-C2 of 8.5 mm or above; and (4) dynamic basion dens interval (BDI) of 2.0 mm or more, as obtained during invasive cervical traction, and calculated by subtracting the BDI at end traction with the BDI off traction, both being measured in the sitting position
Two hundred fifty patients underwent OC fusion using a total of 500 condylar screws between September 2012 and September 2018

Summary

Introduction

Occipito-cervical (OC) fusions are used to treat a variety of pathologies affecting the craniocervical junction [2, 5, 7, 8, 20]. Condylar screws have been recently introduced as a rescue technique for OC fusions, whenever an existing craniectomy, or a fractured or thin supraocciput limit the available fixation points to the occipital squama [1, 21]. Concerns regarding potential complications have slowed the use of this technique far. We present the complications and safety analysis of a single-surgeon series of 250 occipitocervical fusions (500 condylar screws)

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Results

Discussion

Conclusion