Infectious pin complication rates in halo vest fixators using ceramic versus metallic pins

Retrospective review of database patients.

To compare infectious pin complication rates utilizing ceramic pins, an emerging technology, with a large database of complications in halo's using metallic pins.

The halo/vest fixator remains a useful modality of treatment for cervical spine trauma but has been described as having a high incidence of complications, foremost pin-related complications. Ceramic pins and vest modifications have been introduced under the premise of (1) decreasing pin-tract infections compared with metallic pins manufactured from stainless steel or titanium and with the advent of 3T MRI, (2) decreasing brain MRI artifact, and (3) lowering MRI intolerance owing to material overheating.

We retrospectively reviewed a prospectively collected patient data set of the Harborview Medical Center spine trauma registry. A historic control group exclusively utilizing metallic halo pins over a 10-year period was compared with patients who were treated with halo's exclusively utilizing ceramic pins over a recent 14-month period. Complications investigated included aseptic, loosening, and infections graded on a novel 3-tier system adapted from external fixation in long bone and periarticular trauma. Inclusion criteria were the patients with traumatic cervical spine injuries treated with a halo for a period of at least 14 days.

Forty-four patients were available for analysis in the ceramic pin group versus 263 in the metallic pin group. Overall pin complications amounted to 40.9% ceramic (C) versus 21.7% metal (M) pins (P<0.05), aseptic loosening rates 13.7% (C) compared with 8.3% (M), and pin site infections 27.3% (C) compared with 13.3% (M) (P<0.05). A grading system for halo pin tract infections was developed. In assessing overall complications and infections specifically, ceramic pins seemed to be associated with a higher incidence of adverse events or complications compared with titanium pins.

Despite the imbalance of size of our cohort groups, there seems to be a strong trend toward the newer ceramic pin technology not meeting expected minimum performance standards set by the earlier metallic material. Causes for the higher failure rate likely lay in the necessary changes made to the halo vest and specifically the pin design owing to the inherent mechanical property limitations of MRI compatible materials.