Successful Triple Flap Procedure for Thumb Reconstruction in Severe Hand Crush Injury

Introduction

A mangled extremity injury or crushed injury is defined as damage to at least 3 out of 4 systems: soft tissue, bone, nerves, and vessels [1]. The resulting injuries to soft tissues, muscles, and nerves are often caused by blunt trauma and have been associated with very high amputation rates [1]. The human hand is an intricate biomechanical structure composed of sensors, nerves, tendons, ligaments, muscles, and joints. Among the 5 digits of the hand, the thumb is the most independent [2]. The thumb is crucial for grasping objects. Along with the foldable palm, it helps create oblique arches that stabilize the orientation and position of the fingers during the manipulation of objects [3]. Various efforts have been made to restore thumb function in cases of crushed injury.

The scapular flap is often used for reconstruction, particularly in the head and neck area. First described by Dos Santos in 1982, the scapular flap, along with the underlying subscapular arterial system, is recognized as the most dynamic donor site available for free tissue transfer [4]. The subscapular artery system provides various flap varieties, including fascio-cutaneous, osteofasciocutaneous, and musculo-osteocutaneous flaps [4,5].

This report presents the case of a 47-year-old man with severe crush trauma to the left hand and loss of the left thumb that was surgically managed using a triple surgical flap procedure to reattach the thumb. The challenge in this case was to maintain the function of the hand through reconstruction, aiming to restore functionality and appearance. This report aims to highlight the use of a triple flap procedure to preserve the function of the crushed thumb.

Case Report

A 47-year-old handyman with no history of comorbid conditions sustained a severe hand injury while installing a water tank at home. The tank fell on his left hand, causing significant deformation. In the Emergency Department, examinations revealed a serious injury, with tendon rupture and loss of dorsal and volar muscles in the thenar region. The vascular status of the distal radial and ulnar arteries was still palpable. Pulse oximetry showed no blood saturation in the thumb, index finger, and middle finger, while the ring and little fingers showed normal results. Imaging confirmed multiple fractures of the phalanges and metacarpals. The patient’s Mangled Extremity Severity Score (MESS) was 9 (Figure 1A, 1B). We recommended transradial amputation, but the patient refused. Therefore, it was agreed to attempt reconstruction to restore both the appearance and function of the hand.

Operative intervention was performed immediately, within 1 day after the incident. The first surgery focused on debriding nonviable tissue and performing a ray amputation on the index finger, as the local infection and MESS score was 9, with high likelihood association of amputation. We identified the damaged artery up to the point where it remained viable and performed anastomosis to preserve the function of the middle and ring fingers. Fractured phalanges and metacarpals were fixed with K-wires. Irreparable tendons were removed, and their remnants were sutured to the surrounding tissue. Three days later, we planned a second surgery to reconstruct the thumb and cover the soft tissue. Preparation was made to harvest a triple flap, consisting of a scapular flap, a parascapular flap, and an osteocutaneous parascapular flap. Vascular evaluation was conducted prior to the procedure by using Doppler ultrasound to identify the circumflex scapular artery and the thoracodorsal artery, tracing them laterally to locate the triangular space. The skin paddle was mapped according to the scapular and parascapular flap designs. The radial artery and vein were identified as recipient vascular sites.

The skin paddle flap was harvested carefully, ensuring all layers of the subcutis and fascia were lifted. The proximal end of the vascular located in the triangular space was ligated and cut. An incision was made on the teres minor 3 cm medial to the lateral scapular border and retracted medially. The teres major muscle and part of the latissimus dorsi muscle attached to the bone segment were exposed from the bone. A bone osteotomy was performed on the lateral border of the scapula, approximately 7 cm in length and 2 cm in width (Figures 1C, 2). A part of the teres minor muscle was left attached to the bone to maintain blood supply. The bone flap was fixed to the remaining carpal bones using two 1.2-mm K-wires, and the skin paddle was shaped and sutured to resemble a thumb. The remaining wound defect was covered with a full-thickness skin graft from the posterior contralateral arm (Figure 3).

Postoperatively, the patient was admitted for flap evaluation and antibiotic therapy. Intravenous heparin was administered as a 5000 IU bolus, followed by a continuous dose of 12 IU/kg/h for 5 days, to prevent vascular congestion. A light source was used to keep the flap warm. The patient was instructed to elevate his hand to about 30 degrees while resting, to improve vascular return. Blood tests were monitored to ensure optimal hemoglobin and albumin levels. Five days after surgery, the flap showed signs of survival, with a warm tactile impression, reddish color, and good capillary refill time. The patient was discharged with instructions for regular outpatient follow-up.

Six months after thumb reconstruction, imaging evaluation showed that the bone flap had fused well with the carpal bones, allowing for the removal of the K-wires. Clinically, his hand demonstrated excellent appearance and functionality, with strong grip strength and no symptoms of pain or disability (Figure 4A, 4B). The patient returned to his daily activities without issues. His Quick Disabilities of the Arm, Shoulder, and Hand score 6 months after surgery was 13.63.

Discussion

Crushed extremity injuries are limb-threatening conditions that can be fatal if not properly treated [6]. Crush injuries to the extremities often lead to these severe conditions, characterized by damage to at least 3 of the 4 systems: soft tissue, bones, nerves, and blood vessels [1]. The key aspects of crush injury management include careful assessment and a reconstruction plan based on the damaged structures [7]. In primary surgery, priorities are thorough debridement, skeletal stabilization, vascular repair, and soft tissue coverage for exposed vessels [7]. Meanwhile, the thumb contributes over 40% of the hand’s overall function, and it is unequivocally prioritized for replantation and reconstruction [8]. In this case, we aim to discuss and explain how the combined triple flap technique can serve as an option to preserve the function and integrity of the thumb.

In thumb reconstruction, the main goals are to restore functional length, stability, movement, sensation, and aesthetics [9]. Various methods for thumb reconstruction depend on injury specifics, defect size, and geometry, including local flaps, regional flaps, and distant free flaps [10]. For major thumb defects distal to the metacarpophalangeal joint, the research of Adani et al suggests that the extended osteo-onycho-cutaneous great toe transfer is the preferred method [11]. However, our patient declined this procedure. Alternative methods, such as using a radial forearm flap or Serratus anterior-rib composite flap, have also yielded good results [12,13].

A study by Matey and Peart reported successful thumb reconstruction in cases where thumb replantation was not feasible [14]. The reconstruction procedures included the pollicization of a partially amputated thumb and the replantation of another amputated digit to the thumb, provided it remained viable. The report also emphasized the importance of immediate reconstruction, as it offers superior functional and aesthetic outcomes, compared with that of delayed reconstruction [14]. Our patient’s condition presented with a bone defect that was more proximal than previously reported cases, necessitating not only the resolution of extensive soft tissue problems but also the reconstruction of hard tissue. Therefore, we opted for a triple flap from the scapula, as it provides an effective solution for both soft tissue and hard tissue reconstruction.

In this case report, we utilized a triple flap, an advanced variation of the scapular flap. The scapula’ unique anatomical structure and the surrounding soft tissue make it a popular source for flaps [15]. Its unique vascular anatomy allows this flap to be combined with other soft tissue flaps to form a chimeric flap, providing broader soft tissue coverage than other flaps [16]. According to Adani et al, dorsal thumb salvage can be reconstructed using various types of flaps, depending on the wound’s location and severity [11]. Koshima et al documented the use of a thoracodorsal artery perforator flap along with a scapular bone flap for the repair of congenital floating thumb [16]. However, to the best of our knowledge, the use of a triple flap for thumb reconstruction has not been reported before. A notable limitation of this procedure is the bulky appearance that results from the use of thicker tissue, compared with the typical tissue found in the hand [17]. Despite this, the procedure offers a viable solution for addressing extensive tissue defects; some clinicians even combine this with a latissimus dorsi flap to cover a large soft tissue defect [18]. Moreover, executing this technique requires a higher level of surgical expertise and advanced skills.

An alternative approach, such as the use of myoelectric prostheses for cases of hand or thumb amputation, can be considered as one of the options [19]. However, we did not consider myoelectric prostheses in this case, because they have not been previously used at our hospital, and government insurance does not cover this item. Despite this, the flap procedure remains advantageous, as it restores comprehensive hand function, preserves sensory capabilities, and provides psychological benefits. After all, this case not only demonstrates the satisfactory outcomes of the triple flap in reconstructing a patient’s thumb but also underscores the importance of tailoring the surgical strategy to the patient’s specific needs.

Conclusions

This report highlights the challenges and limitations of treating severe hand crush injuries and emphasizes the importance of personalized surgical approaches, such as a triple flap, for optimal outcomes. Based on our reported case, the triple flap has the potential for complex thumb reconstruction cases. Further studies with more cases are needed to validate the use of this flap in various settings.