Determination of the adequate vascular perfusion time of cross-leg free latissimus dorsi myocutaneous flaps in reconstruction of complex lower extremity defects.

[BACKGROUND] Lower limb defects may be present due to various causes including infections, vascular diseases, tumor resections, and crush or avulsion injuries. Management of lower leg defects is a complex problem, especially when they are large with deep soft tissue loss. These wounds are difficult to be covered with local skin flaps, distant skin flaps or even conventional free flaps because of the compromised recipient vessels. In such cases, the vascular pedicle of the free flap could be anastomosed to the recipient vessels of the contralateral healthy leg temporarily and then divided after adequate neo-vascularization of the flap from the wound bed. The ideal time to divide such pedicles should be investigated and accurately assessed to have the maximum success rate possible for these challenging conditions and procedures.

[METHODS] Sixteen patients who did not have a suitable adjacent recipient vessel for free flap reconstruction had been operated with cross leg free latissimus dorsi flap between February 2017 and June 2021. The mean soft tissue defect dimension was 12 × 11 cm (the smallest 6 × 7 cm; the largest 20 × 14 cm). Gustilo type 3B tibial fractures were present in 12 patients, while no fractures were present in the other 4 patients. Preoperatively, arterial angiography was performed on all patients. After the fourth week post-operatively, non-crushing clamp was applied around the pedicle for 15 minutes. The clamping time was increased by 15 minutes on each consequent day (average 14 days). On the last 2 days, the pedicle was clamped for 2 hours, and bleeding was assessed by a needle prick test.

[RESULTS] Clamping time was assessed in each case to reach a scientific calculation of the adequate vascular perfusion time needed for full flap nourishment. All flaps survived completely except two cases of distal flaps necrosis.

[CONCLUSION] Cross-leg free latissimus dorsi can provide a solution for large soft-tissue defects in lower extremities especially with absence of any suitable recipient vessels or when the use of vein grafts would not be feasible. However, ideal time before dividing the cross vascular pedicle should be identified to have the maximum success rate possible.