ObjectiveTo observe the effectiveness of lateral arm free perforator flap by personalized design in repairing irregular defects of the hand. MethodsTwelve patients with irregular defects of the hand were repaired with lateral arm free perforator flaps by personalized design between January 2010 and January 2015. There were 7 males and 5 females with a mean age of 35 years (range, 18-52 years). The causes included crush injury in 5 cases, thermal injury in 3 cases, traffic accident injury in 2 cases, and friction injury in 2 cases. The time between injury and admission was 1.0-4.5 hours (mean, 3.1 hours). In 3 patients with skin and soft tissue defect of approximate square, the flap of less than 6 cm in width was designed and was segmented into foliated flaps to repair wound; the bilobed flaps were used in 5 cases of hand penetrating wounds; the bilobed flaps or trifoliate flaps were used in 4 cases of multiple finger skin soft tissue defects. The total area of the defects ranged from 6.0 cm×5.0 cm to 9.0 cm×8.0 cm, and the area of flap ranged from 10.0 cm×3.5 cm to 12.0 cm×6.0 cm. All the wounds at donor site were closed directly. ResultsAll the flaps survived, wounds and incisions at donor sites healed by first intention. The patients were followed up 6-15 months (mean, 10 months). Bulky flaps were observed in 2 cases of female patients, and flap thinning was performed at 3 months after operation. The hand function recovered satisfactorily, and the sensation was S1-S3 at 6 months after operation. According to the functional assessment criteria of upper limb formulated by the Hand Surgery Branch of Chinese Medical Association, the results were excellent in 2 cases, good in 7 cases, fair in 2 cases, and poor in 1 case. The linear scars was observed at the donor site. ConclusionThe lateral arm free perforator flap has constant vessels anatomy, and there are many perforators in the intermuscular septum. The lateral arm free perforator flap by personalized design can repair irregular defects of the hand.