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

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.

Developmental pattern of tibiofemoral angle in healthy north-east Indian children

PURPOSE

Physiological range of tibiofemoral angle (TFA) is poorly defined and may lead to unnecessary therapeutic interventions. Studies on TFA developmental pattern suggest that racial and ethnic differences are present; children in north-east India who have not yet been studied need to be evaluated.

PATIENTS AND METHODS

Cross-sectional study of clinical TFA, intermalleolar distance and intercondylar distance in 1020 healthy north-east Indian children aged from 2 to 18 years was done. Height, weight and body mass index were also recorded.

RESULTS

At two years of age the mean TFA was valgus. The values reached a peak of 8.55° (standard deviation (SD) 1.01) valgus at seven years of age. The TFA then gradually stabilised to 3.18° (SD 1.18) valgus by 18 years of age. There was no significant difference in TFA between male and female patients.

DISCUSSION

The present study is the largest and only the third such study on Indian children and the first on healthy northeast Indian children. By the end of two years most children had valgus angulation. This, along with the peak angulation observed, was similar to most of the other studies. The age at peak angulation and subsequent stabilisation of valgus angulation varied greatly among children of different origins, especially non-Indian children.

CONCLUSIONS

Data can be used to identify children who require further follow-up/evaluation and can serve as guidelines during deformity correction and future studies. The development of TFA in this cohort is not different from other children of India but differs from children of other ethnic origins.