A 59-year-old man with no underlying disease visited the emergency department for penetration injury of the left palm caused by paint gun injection (Table 1). A small entry port with minor swelling and redness was noted from the initial examination (Fig. 1A). Computed tomography (CT) imaging workups of the left hand showed a 1×1 cm-sized foreign material located in the soft tissue above the flexor tendon sheath (Fig. 1B, 1C). Surgical debridement and foreign material removal were sequentially performed 2 days after injury. Unfortunately, through Bruner’s incision, the emulsion paint was shown to strongly adhere to the surrounding structures such as the lumbrical muscles, common digital nerves from the median nerve, and even to the skin and fat layers (Fig. 1D). Inspection revealed partial injury to the tendon sheath, while the tendon itself was preserved. Meticulous dissection and skeletonization of the affected structures were necessary. After copious irrigation, the surgical wound was closed by placing a Penrose drain (Fig. 1E). During daily observation, the drain was removed on postoperative day 2. In addition, wound culture revealed no pathogen presence. Accordingly, the approximated wound showed satisfactory progress, and the patient was discharged 4 days after surgical intervention. The wound and function of the hand including flexion and extension were completely healed without any infection, necrosis, or limitation of motion (Fig. 1F).

A 57-year-old male with hypertension suffered an injury to his left palm by a high-pressure injection gun (Table 1). The high-pressure water-soluble acryl emulsion paint penetrated the skin of the first web space (Fig. 2A). From the first inspection, the entry port was approximately 0.5 cm in size, and minor swelling and redness were noted. The patient complained of pain and tenderness, although no limitations of motor function and sensory impairment were observed. Wide spreading of the radiopaque lesion (considered as the foreign material) across the dorsal area of the hand was verified in the X-ray imaging test (Fig. 2B). The patient immediately received broad-spectrum antibiotics before undergoing surgery, including exploration and wide debridement, 5 hours after injury. Similar to the first case, the emulsion material was found to be strongly adhered to the first dorsal metacarpal artery and deep fascia; thus, debridement with skeletonization for nerves or vessels was performed under a microscope. Following the extension incision to the dorsal area, the same procedure was repeated for the accumulated material (Fig. 2C). No nerve or vessel injury was identified. Gentle closure of the wound after copious irrigation was performed, and the wound culture test showed normal skin flora. The patient returned home on the 7th day of hospitalization. His hand function was almost restored sufficiently for him to return to work. The patient reported no distinct discomfort throughout the 6 months of observation (Fig. 2D).

A 63-year-old male with diabetes, hypertension, and chronic kidney disease injured his left palm using a high-pressure injection gun (Fig. 3A, Table 1). CT scanning showed that the injected material spread through the palm and even the hand dorsum (Fig. 3B, 3C). Worse still, the radiopaque material was widespread to the third and fourth metacarpal area of the left palmar and dorsal hands. Initially, the patient was referred to an orthopedic surgeon on duty. After surgical exploration and debridement, he was subsequently transferred to the plastic surgery department for further debridement, removal of residual foreign bodies, and reconstruction. Prior to the reconstructive procedure, another wide debridement involving radical dissection of the surrounding structures was conducted (Fig. 3D). The infiltration of the emulsion paint into the skin and adipose layers was extensive, and wide resection of the volar skin envelope, including the entry port, was required. Subsequently, sequential flap reconstruction for soft tissue coverage was continued. A radial forearm flap from the contralateral side was chosen to cover the same defect; this flap was designed as a 3.5×10-cm elliptic shape with a long tail to ensure the anastomosis site from the injury zone of the palm. Consequently, the flap was raised and transferred to the defect with end-to-side anastomosis to the radial artery near the wrist and end-to-end anastomosis to the vena comminates and superficial branch of the cephalic vein. The flap settled into the area gradually, and rehabilitation therapy has begun. The flap debulking procedure with minor revision is ongoing to facilitate hand function, and his hand function was recovered up to 90° of flexion at the proximal interphalangeal joint and 30° of flexion at the distal interphalangeal joint at his 9-month follow-up (Fig. 3E, 3F, 3G). Furthermore, the patient was also able to perform activities such as grasping a cup.