Limitations of Computed Tomography Angiography in Preoperative Planning of Peroneus Brevis Rotational Flap

Abstract

The distally based peroneus brevis (PB) rotational flap has been shown to be a reliable method of coverage of distal third tibial wounds. The flap is perfused via retrograde flow from distal PB perforators located within 8 cm of the lateral malleolus. The ability to assess patency of these vessels preoperatively facilitates surgical planning, and computed tomography angiography (CTA) has been used for perforator assessment of other lower extremity flaps. The purpose of the present study is to establish the potential utility of standard CTA for locating distal PB perforators by examining uninjured lower extremities.

Methods: Twenty-five patients who underwent bilateral lower extremity CTAs using standard lower extremity protocol were retrospectively identified. Axial two-dimensional images were scanned craniocaudally using our institution's standard CT image viewing software, Merge Radsuite (Merge Healthcare, Hartland, Wis.).

Results: The average location of distal-most PB perforators identified on CT angiogram was 13.1 ± 5.1 cm proximal to the distal fibula, or 34.5% ± 13.5% of total fibular length. Standard CTA was only able to locate a pedicle within 8 cm of the lateral malleolus (20.9% of fibular length) in three of 25 patients (12%).

Conclusions: Previous studies have described a reliable pedicle within 8 cm of the distal fibular tip upon which to design a distally based PB rotational flap. The absence of such perforators in the CT angiogram suggests that standard CT angiogram is not a reliable technique for identifying the patency of such perforators when evaluating the utility of a distally based PB flap.

Fig. 1.

Techniques of peroneus brevis flap harvest. A, Exposed fibula after debridement of lateral ankle abscess. B, Exposure of peroneus longus and PB. C, Proximal PB mobilization. D, Reflection of PB distally. E, Lateral ankle defect covered by reflected PB. F, Inset with split-thickness skin graft.

Fig. 2.

Lower extremity angiogram was utilized to identify peforators. A, Example of lower extremity computed tomography angiogram. B, Perforator identified (red arrow) originating from the peroneal artery. C, Location of perforator in the middle third of the fibula.

Fig. 3.

The decile distribution of perforators to PB as identified by computed tomography angiography along the fibula. The green line represents the maximum distance from the distal fibula for a perforator to be viable for rotational flap surgery.

Fig. 4.

A scatter plot of the location of all perforators identified by computed tomography angiography. Perforators include those to the PBPA, those to the PBTA, those for the ALT, and those for the MSAP. Their location is represented by decile distribution along relevant anatomical measurements: thigh length for ALT, and fibular length for PBPA, PBTA, and MSAP.

Fig. 5.

A scatter plot of the caliber of all identified PB perforators with respect to their location, represented as distance along the fibula.