Hook nail treatment – a bulky palmar flap as an alternative to the “antenna” procedure and to the thenar flap for fingertip coverage

Dear Sir,

Deformities of the fingernail mostly represent aesthetic rather than functional indication for surgical correction. The hook nail (claw nail or parrot beak) deformity following partial distal phalangeal bone and pulp loss develops because of palmar pull of the terminal nailbed by wound contraction or by wound suture. The treatment concepts include proximal relocation of the entire nail complex [1], excision of the curved part of the nailbed [2], the “antenna” procedure that along with restoration of deficient soft tissue of the fingertip includes K-wiring to keep the repositioned nailbed straight [3], and osteocutaneous reconstruction of the fingertip.

In the “antenna” procedure cross finger flap and homodigital advancement flap have been used for fingertip coverage. These approaches carry certain disadvantages. The use of K-wires is associated with traumatization of the nail and inconveniences of the space-occupying hardware removal. The cross finger flap may jeopardize function of the donor digit and result in unsightly dorsal scars. The advancement flaps require extensive dissection, are limited in size, tend to contract, and may leave interfering scars. The other fingertip reconstruction approaches, such as sliding, island, and microvascular flaps, are technically demanding, require extensive dissection, and may also produce problematic scars.

The named risks could be alleviated by employing the pedicled thenar flap, which, however, is cumbersome to use for the two ulnar digits and restricts mobility of the thumb. Furthermore, the thenar flap, as well as the cross finger flap, is of limited thickness, which may lead to nail deformity recurrence. In comparison, non-thenar palmar flaps, rarely used because of fear of contractures [4], offer durable skin and ample of bulk. Leaving the thenar eminence intact preserves postoperative mobility of the thumb. Palmar skin defects have great potential for uneventful spontaneous healing.

Recently, a pedicled midpalmar flap has been employed in reconstruction of traumatic defects of the fingertip of the middle finger [4]. The authors designed the flap radial to the proximal (oblique) palmar crease, i.e., at the base of the thenar eminence, to hide the donor scar in the fold. Similarly, as in the thenar flap, this feature of the technique may be difficult to apply for the two ulnar digits.

Fig. 1 and 2 represent cases of curved nails to show not only a solution of the latter problem with ulnopalmar pedicled flaps but also an alternative treatment of this deformity. In both cases, following excision of scars, pedicled ulnar palmar flaps were used to support the repositioned nail complex. K-wire pinning to keep the nailbed straight was not necessary due to the robustness of the palmar skin. No immobilization except bandage and finger-to-palm suture was used, which afforded thumb-index pinch for daily activities. The recipient wounds of both patients and the donor wound in case 2 were left for spontaneous healing to avoid wound tension and necrosis. The patients were satisfied with the improvement of nail appearance and reported no functional problems.

Restoration of the fingernail length was not attempted. A simple way of nail lengthening is to move the eponychial tissue proximally to expose the hidden part of the nail plate. This procedure could be performed at a later time after correction of the nail deformity. Nail dimensions could also be increased by bone support restoration along with nailbed grafting. This approach lengthens the overall healing time and may fail due to bone resorption. Furthermore, skeletal lengthening necessitates a larger skin flap, since the normal nailbed is projecting well beyond the phalangeal bone (Fig. 1A). Osteocutaneous fingertip restoration could probably be best done by partial toe transfer, which would be associated with the difficulties of microvascular surgery and complexities due to mismatch between the finger and toe nail sizes as well as between the recipient and donor wound circumferences.

Inconveniences of staged surgery is a shortcoming of pedicled hand flaps. However, in terms of the time required for regrowth of the removed nail plate, the overall length of treatment may be similar across all reconstructive approaches for hook nail deformity.

Avoiding any manipulation of the inset flap right after pedicle division is a classical approach to prevent necrosis of the weakly perfused flap edges. Due to limited fingertip tissue mobility, it is safer to leave the recipient wounds for complete secondary healing rather than to attempt direct closure early after pedicle division. This is particularly noteworthy in the cases of miniature flaps. Spontaneous remodeling can even be expected in oversized flaps (Fig. 1C, E).

Preventing late sequelae of fingertip injuries is an important strategy in their management [5]. Literature search did not reveal cases of pedicled palmar flap application for correction of the hook nail deformity. The proposed flap-only technique fits well into the “reconstructive ladder” concept by leaving perspectives for other surgical options open. This report suggests that injury to the nail complex by supportive K-wires could be avoided by ample soft tissue cushioning of the repositioned nailbed. Scars are less conspicuous in the non-thenar palm than in the thenar. Some recurrence of hook nail deformity is usually seen regardless of reconstruction technique, which seems to be due to shrinkage of the restored soft tissue padding of the distal nailbed. A bulky pedicled ulnopalmar flap could be a useful treatment in the hook nail deformity as well as in other cases of fingertip defects of the two ulnar digits.

Conflict of interest: No conflict of interest.

Acknowledgment: The presented patients were treated by the author from 2012 till 2015 at Vilnius University Hospital “Santaros Klinikos”.

Valdas Macionis, MD, PhD

Independent researcher

Vilnius

Lithuania

e-mail: valdas.macionis.md@gmail.com