INTRODUCTION

The thumb is crucial to hand function and the ability to carry out daily duties like gripping, holding, opposing, circumducting, and movement. Traumatic injuries to the thumb are common in injuries to the hand [1], and the thumb has a greater impact on hand function than other fingers [2]. The end organ for touch is the tip of the thumb, which is covered in unique sensory receptors that allow the hand to detect touch. Loss of fingertip sensation due to complex damage to the thumb tip presents difficult issues for hand surgeons [1]. Preserving length and regaining function, sensibility, and a pleasing appearance are the goals of reconstruction. In addition to soft tissue coverage, trauma can cause soft tissue loss, which is linked to vascular injuries that require revascularization [1]. After a thumb amputation, replantation is the most frequently advised surgical procedure to regain both function and appearance. When the severed section cannot be replanted, alternative reconstruction methods include skin grafting and the use of local, distal, and free flaps. The degree and scope of the injury influence the treatment decision. For wounds with exposed bone or tendon, flap reconstructions are typically preferred over secondary healing or skin grafting [3]. The neurovascular island pedicle flap is a dependable method for reconstructing the thumb pulp. In 1953, the island flap taken from the medial side of the third or fourth finger for reconstruction of the thumb was initially demonstrated by Littler [4]. The island flap offers robust fasciocutaneous structures and sufficient tissue with a comparable morphology for one-stage repair. Furthermore, the process has a reduced operation time and only needs one operation field, making it quite simple and safe. Venous congestion, scar contracture, numbness, cold sensitivity, and hyperesthesia are among the problems associated with flap surgery. Specifically, the “double sensibility" of the flap, or the inability of the donor and recipient to switch senses, can be a concerning postoperative clinical issue [5]. We report how the heterodigital island flap achieved an excellent outcome in the reconstruction of a thumb-pulp defect.

CASE REPORT

A 48-year-old right-handed female housewife was referred to the hospital for an injury to her left thumb caused by a blender machine. Inspection showed a soft tissue defect, mostly on the volar region at the level of the distal interphalangeal thumb. She had partial loss of the nail and pulp and thrombosis of the digital artery, but no fracture of the distal phalanx (Fig. 1A). The preoperative QuickDASH (quick Disability of the Arm, Shoulder and Hand) score was 36.4. Debridement and primary sutures were done to maintain the integrity of the original thumb (Fig. 1B). A few days later, the thumb blackened and was not viable (Fig. 1C). A heterodigital island flap raised from the ulnar aspect of the middle finger was used to revascularize the thumb and resurface the 2.5×2.0-cm defect over the distal thumb. Meanwhile, the donor defect from the middle finger was resurfaced with a skin graft from the radial forearm (Fig. 2). A 2-month follow-up revealed appropriate skin color and texture, good soft tissue cover, and a high level of resemblance to the contralateral thumb (Fig. 3). The skin graft also looked good. The flap demonstrated outstanding vitality, with no flap loss, partial necrosis, or superficial sloughing with the interphalangeal fusion. Sufficient sensory recovery without discomfort or double sensation was also attained. No hypoesthesia, hyperpigmentation, donor site morbidity, or cold intolerance of the ulnar aspect of the donor digit were present. At the 4-month follow-up, the flap had settled well (Fig. 4), and the patient had a postoperative QuickDASH score of 11.4, allowing her to resume normal activities. Her keloid scar, however, caused the flap shape to appear larger than it actually was.

Ethics statement

Written informed consent for publication of the research details and clinical images was obtained from the patient.

DISCUSSION

The thumb is rich in nerve endings and is essential for actions like pinching, gripping, and grasping. Therefore, sensory restoration is crucial in thumb-tip deformities. Modes of injury can include assaults, traffic accidents, mixer/grinder injuries, and injuries from workplace machinery. Injuries caused by rapidly moving blades are typically the result of carelessness, as demonstrated in this instance, where an attempt to retrieve an object with her fingers from between ostensibly fixed blades resulted in injury.

A quick diagnosis can be made using clinical history, examination, and plain photo of the injured digit. Because the thumb is the main component of hand function, it is necessary to make every effort to restore the thumb's mobility, length, stability, and sensation following a hand injury [2]. Direct suture is the gold standard approach for emergency restoration of normal palmar digital nerves [1]. Depending on the specific circumstances of an injury, there are various methods for repairing the remaining thumb when replanting a severely injured thumb is not an option [6]. The goal of thumb reconstruction is to restore sensory function to the tip by employing tissue that has the volume, texture, and contour of volar pulp [1].

Treatment modalities include dressing changes, diverse local transfer flaps, and free flaps [7]. The best course of action for fixing a thumb-tip deformity without exposing the phalangeal bone is to change the dressing [6]. Nonetheless, flap covering is advised if the thumb-tip deformity is accompanied by phalangeal bone exposure. In our clinical practice, both the free lateral great toe flap and the modified heterodigital neurovascular island flap have produced positive outcomes [8].

The ulnar aspect of the middle finger or the radial aspect of the ring finger can be used to create the sensate, vascularized Littler flap [4]. For significant finger abnormalities, this flap can offer a comparable texture and sensory covering; it is particularly well suited for the pulp of the thumb. The heterodigital neurovascular island flap has undergone modifications since it was initially described by Littler [4] in 1953. These modifications include those made by Adani et al. [5], Wang et al. [7], and Lee et al. [9].

All of these techniques produce acceptable results when compared to the island flap and free flap, although the effects on donor site morbidity vary. Patients are more likely to have numbness, cold intolerance, and other symptoms when the donor site is on the hand, especially when damage to the donor site is unavoidable. In more extensive hand wounds, flap removal and transposition are necessary since the finger flap donor site is on the same hand as the wounded thumb. When the donor site is on the foot, the toe flap approach seems to provide a more satisfactory overall appearance of the hand. In terms of cold intolerance, the toe flap technique is preferable to the finger flap method. However, with the finger flap, the site of cold intolerance is mostly concentrated at the donor site, which is covered with a skin graft. This may be because there is less obstruction of blood flow to the affected hand after a toe flap procedure. Large wounds at the operative sites and a sacrificed digital artery on the donor finger are possible in the finger flap group. However, the finger flap has benefits of its own. Clearly, the operation is easier and requires less microsurgical skill than a free lateral great toe flap. When compared to the toe flap technique, individuals undergoing finger flap surgery typically spend less time in the hospital and do not need to remain in bed after the treatment. In addition, treatment costs are likely lower with the finger flap method than with a tissue transfer from the toe.

Although primary suturing and debridement were the initial treatments in this case because the patient's affected thumb side was still whole, failure occurred and the choice to reconstruct using a heterodigital island flap was made. This situation fits the criteria for applying a heterodigital island flap. As stated by Pham and Netscher [10], heterodigital island flaps can be used for the following reasons: (1) large dorsal and volar finger deformities, up to 3.5 cm long; (2) fingertip wounds that require a flap with a larger rotational arc, which cannot be accessed by immediately-adjacent tissue transfer; (3) when it allows for complete skin closure and reduces the possibility of infection to internal prosthetic devices, a single-stage repair of the soft tissues of the finger is preferred over a cross-finger flap; (4) in order to minimize stiffness and enable early digital motion, single-stage reconstruction is preferred; and (5) when a finger needs more blood flow to promote wound healing because it has been previously weakened by severe scarring, an earlier infection, or radiation damage. Contraindications for heterodigital island flaps are as follows: (1) a crushing or piercing wound, particularly if it affects more than one finger or the distal palm, which may contain pedicle vessels; (2) after serious infections in the distal palm that could jeopardize donor arteries; and (3) due to potential vascular compromise to both the donor finger and the transplanted flap, these arterialized pedicle flaps may be somewhat contraindicated in smokers and people with peripheral vascular disease.

In this case, a radial forearm skin graft was applied to the donor site, and the patient reported no significant pain, discomfort from scars, or difficulties in her recovery. Selection of this technique may reduce donor site morbidity. Many novel techniques for covering the donor site have been developed in response to concerns about cosmetic and functional morbidity at the site. One such technique is skin grafting. Because radial forearm skin grafts are placed close to the donor site, only the surgical site is draped, and the skin color of the recipient and surrounding area is nearly the same.

The primary drawbacks of this technique are reduced discrimination sensitivity over time, limited somatosensory cortical integration, flexion contracture, and cold intolerance. The morbidity at the donor site is almost always the same: partial hypoesthesia, trophic abnormalities, pain, and deficiencies in temperature perception [1,10].

Finger injuries are common. When digital reconstruction is required, replantation is still the gold standard. However, there are several reconstruction methods available in cases where replantation is not feasible. Covering massive digital defects that encompass the pulp with glabrous, sensitive, elastic, and well-vascularized skin in a single surgical step is made possible with the heterodigital island flap. Morbidity at the donor site is manageable. In addition to aiming for the best possible sensory recovery following surgery, postoperative rehabilitative care should also minimize issues related to donor digit healing. In summary, the heterodigital island flap is an excellent alternative for the reconstruction of thumb deformity and produces outstanding functional and aesthetic outcomes.

ARTICLE INFORMATION

Author contributions

Conceptualization: all authors; Methodology: all authors; Investigation: all authors; Supervision: DPSB, MS; Writing–original draft: BDS; Writing–review & editing: all authors. All authors read and approved the manuscript.

Conflicts of interest

The authors have no conflicts of interest to declare.

Funding

The authors received no financial support for this study.

Data availability

Data sharing is not applicable as no new data were created or analyzed in this study.

Fig. 1.

Clinical images before and after initial surgery. (A) A nearly amputated left thumb injury. (B) Palmar side after debridement and primary sutures. (C) Blackened left thumb several days after initial surgery.

Fig. 2.

Intraoperative images. (A) Design of a heterodigital island flap on the ulnar aspect of the middle finger. (B) The heterodigital island flap raised from the ulnar aspect of the middle finger. (C) Thumb defect resurfaced with the flap and the donor site defect resurfaced with a skin graft from the radial forearm region.

Fig. 3.

Two-month follow-up images. (A) Palmar view showing appropriate skin color and texture, as well as good soft tissue cover, although a keloid scar had begun to form. Functional outcomes such as (B) grasping and (C) opposition were accomplished.

Fig. 4.

Four-month follow-up images. (A) Palmar view showing that the flap and skin grafts more closely resemble the normal surrounding skin. Functional outcomes such as (B) opposition and (C) grasping were good and getting stronger.

REFERENCES

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Figure & Data

References

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