Safe corridor for fibular transfixation wire in relation to common peroneal nerve: A cadaveric analysis

Abstract

Background: Peroneal nerve impalement is a recognized complication of percutaneous placement of fibular transfixation wires by palpatory method after increase use of ilizarov technique in treatment of Tibial fractures, deformity correction and limb lengthening. The purpose of this study was to identify the relationship between the Common Peroneal Nerve (CPN) and the palpable landmark, fibular head for insertion of proximal fibular transfixation wire, safe zones in proximal tibia and percentage of fibula where nerve crosses the neck.

Methods: Standard 1.8-mm Ilizarov k- wires were inserted in the fibula head of fresh 10 un-embalmed cadaveric knees. Wires were inserted percutaneously to the fibula head by palpatory technique. The course of common peroneal nerve was dissected. Distances from wire entry point to the course of the common peroneal nerve were measured post-wire insertion.

Results: The mean distance of the common peroneal nerve from the anterior aspect of the broadest point of the fibular head was 25.10 ± 4.39 mm (range 16-35 mm). Common peroneal nerve was seen to cross the neck of fibula at a mean distance of 32.3 ± 8.53 mm (range 20-50 mm). Wire placement was found to be on average, 46% of the maximal AP diameter of the fibula head and 44% of the distance from tip of fibula to the point of nerve crossing fibula neck.

Conclusion: We recommend Proximal fibula transfixation wires are safer to pass with in 2 cm from the tip of the styloid process of the fibula, Anterior half of the head of fibula, <8% of total fibular length, Ventral half of the anterior compartment to avoid injury to peroneal fan. The palpable landmark of fibula is a misinterpretation; it is just the prominent subcutaneous portion of fibula and not the styloid process of fibula which on dissection was located much posterior. Better to take fluoroscopic guidance in difficult cases where palpation of head of fibula is difficult.

Keywords: Common peroneal nerve; Fibula transfixation wire; Ilizarov fixation; Safe corridor.

Fig. 1

The Xray and CT images showing the Comminuted tibial plateau fracture with intact fibula, buttressing effect of fibula with fibular transfixation wire.

Fig. 2

The fibular head and joint line marked with red colour paint before wire insertion, perpendicular lines drawn tangential to superior, anterior and inferior palpable borders and its intersection point is marked as centre for wire insertion.

Fig. 3

1.8 mm k wire passing in to center of fibular head after palpation.

Fig. 4

The two needles marks the AP dimensions of broadest part of head of fibula.

Fig. 5

The needle on right shows tip of styloid process of fibula and on the left shows the point where nerve crosses fibula, CPN is painted yellow in this picture.

Fig. 6

Schematic representation of measurements and calculations.

Fig. 7

The CPN (yellow colour painted) is far posterior to posterior surface of fibula separated by the part of lateral belly of gastrocnimeus.

Fig. 8

The Close proximity of the nerve to posterior aspect of fibula as denoted by needle.

Fig. 9

Palpatory center of head of fibula.

Fig. 10

Actual center of fibular head was posterior as compared to palpatory center. Black border shows the palpatory center and red border shows the actual border of fibula.

Fig. 11

Quadrant diagram shows the Postero superior and Postero inferior locations of nerves in our study. The lowest was 14 mm from anteriormost part of head of fibula.

Fig. 12

Broad fanning of CPN with its branches shown in this picture.

Fig. 13

(a,b) Variable recommendations of proximal fibula wire placements; Red ring shows close proximity of the nerve when placed through head of fibula as in Fig b.

Fig. 14

Wires anterior to fibular head shows hardly any purchase on tibia but when given through fibula head we get good purchase and better hold of comminuted fragments.

Fig. 15

Safe corridor for placement of proximal fibula transfixation pin. A – Tibial tubercle, B – Tip of styloid process of fibula. A perpendicular from AB parallel to fibula will divide in to anterior and posterior compartments. Green shaded area shows the safe corridor for wire placements.