Application of augmented reality technique in repairing soft tissue defects of lower limbs with posterior tibial artery perforator flap

Abstract

To investigate the accuracy and reliability of augmented reality (AR) technique in locating the perforating vessels of the posterior tibial artery during the repair of soft tissue defects of the lower limbs with the posterior tibial artery perforator flap. Between June 2019 and June 2022, the posterior tibial artery perforator flap was used to repair the skin and soft tissue defects around the ankle in 10 cases. There were 7 males and 3 females with an average age of 53.7 years (mean, 33-69 years). The injury was caused by traffic accident in 5 cases, bruising by heavy weight in 4 cases, and machine injury in 1 case. The size of wound ranged from 5 cm×3 cm to 14 cm×7 cm. The interval between injury and operation was 7-24 days (mean, 12.8 days). The CT angiography of lower limbs before operation was performed and the data was used to reconstruct the three-dimensional images of perforating vessels and bones with Mimics software. The above images were projected and superimposed on the surface of the affected limb using AR technology, and the skin flap was designed and resected with precise positioning. The size of the flap ranged from 6 cm×4 cm to 15 cm×8 cm. The donor site was sutured directly or repaired with skin graft. The 1-4 perforator branches of posterior tibial artery (mean, 3.4 perforator branches) in 10 patients were located by AR technique before operation. The location of perforator vessels during operation was basically consistent with that of AR before operation. The distance between the two locations ranged from 0 to 16 mm, with an average of 12.2 mm. The flap was successfully harvested and repaired according to the preoperative design. Nine flaps survived without vascular crisis. The local infection of skin graft occurred in 2 cases and the necrosis of the distal edge of the flap in 1 case, which healed after dressing change. The other skin grafts survived, and the incisions healed by first intention. All patients were followed up 6-12 months, with an average of 10.3 months. The flap was soft without obvious scar hyperplasia and contracture. At last follow-up, according to the American Orthopedic Foot and Ankle Association (AOFAS) score, the ankle function was excellent in 8 cases, good in 1 case, and poor in 1 case. AR technique can be used to determine the location of perforator vessels in the preoperative planning of the posterior tibial artery perforator flap, which can reduce the risk of flap necrosis, and the operation is simple.