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Foot Ankle Int. 2012 Jun;33(6):519-23. doi: 10.3113/FAI.2012.0519.

Precision of targeting device for subtalar screw placement.

Author information

1
University of Zurich, Department of Orthopaedics, Zurich, Switzerland.

Abstract

BACKGROUND:

When performing subtalar arthrodesis, proper screw placement is fundamental to provide primary stability and to help ensure bone healing. In inexperienced hands this step can be time-consuming and exposes surgeons and patients to radiation. By means of a targeting device these potential drawbacks and dangers could be reduced. It was hypothesized that a specifically designed targeting device would reduce radiation exposure while improving screw placement when compared with the conventional "free-hand'' method.

METHODS:

Twenty matched-pairs of cadaveric hindfoot specimens (Thiel fixation) were prepared for the purpose of the study. The specimens were randomly assigned into two groups consisting of 10 specimens each: in Group 1 screw placement was performed with the targeting device and in Group 2 screw placement was performed under fluoroscopic control. Screw placement was radiographically judged to be optimal, suboptimal and poor. An experienced, fellowship-trained foot and ankle surgeon and a resident, who had never done subtalar fusions performed the screw placements. Exposure to radiation was assessed by means of the dose area product given by the fluoroscope.

RESULTS:

Optimal screw positioning was achieved in both groups in ten out of 20 specimens (Group 1, n=5; Group 2, n=5). Suboptimal screw placement was found in eight cases (Group 1, n=4; Group 2, n=4). There were two failures which occurred in fusions performed by the resident (Group 1, n=1; Group 2, n=1). Exposure to radiation was significantly reduced in Group 1 when compared with Group 2 (4.1cGy* cm2 versus 8.1cGy* cm2; p=0.012). No lesion of neurovascular structures due to aiming device placement occurred in Group 1.

CONCLUSION:

A target-device for screw-placement did not provide a significant technical advantage but did result in less radiation exposure.

PMID:
22735327
DOI:
10.3113/FAI.2012.0519
[Indexed for MEDLINE]

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