Hook nail deformity in a child – treatment option with bone graft and thenar flap. Case study with pros and cons
Deformacja „hook nail” paznokcia u dziecka – wady i zalety operacji z przeszczepem kostnym i płatem z kłębu kciuka. Analiza przypadku
Introduction. Hook nail deformity is a common complication following fingertip amputations. Loss of distal bone support and palmar pulp tissue, results in the volar curving of the nailbed, which may cause pain, and aesthetic and functional problems. A few procedures have been described to address nail deformity, including flaps, skin and bone grafts, and microsurgical transfer. Unfortunately, none of the techniques provides reliably good and persistent correction.
Case report. An 8-year-old boy sustained amputation of the distal phalanx of the middle finger and underwent surgical closure of the wound. After 4 years, the patient was admitted to our Department due to a deformed hook nail, which was aesthetically distressing. The hook nail was curved volarly and obliquely. The radiographs showed the lack of a significant part of the distal phalanx.
Treatment. Surgical reconstruction of deficient distal phalanx was performed. The iliac bone graft, inserted into the distal phalanx, was stabilized with two K wires. A Pedicled flap of full-thickness from the thenar was used to cover skin loss over the fingertip. Pedicle division was performed at around 4 weeks. “K” wires were removed after 4 months.
Results. The procedure was well-tolerated by the patient, and no complications occurred. Bone graft provided solid support for the nail bed during healing. Adequate growth and aesthetics of the hook nail were achieved. At 2 years follow-up, slight rotation of the nail was observed, which could have resulted from partial graft resorption and growth of the patient. The patient was satisfied with the treatment.
Conclusions. Although perfect restoration of the nail bed length and pulp contour remains unobtainable, our result showed stable correction of the hook nail deformity.
Wstęp. Wtórna deformacja płytki paznokciowej typu „hook nail” jest częstym skutkiem amputacji palca na poziomie paliczka dystalnego. Ubytek paliczka dystalnego, będącego podparciem kostnym, jak i ubytek tkanek miękkich w obrębie opuszki powoduje zagięcie płytki paznokciowej w kierunku dłoniowej, co skutkuje bólem, upośledzeniem funkcji oraz defektem kosmetycznym palca. Istnieje wiele technik chirurgicznych mających na celu odtworzenie prawidłowego wzrostu paznokcia, takie jak: wykorzystanie płatów skórnych, przeszczepy skóry i kości, jak również transfer mikrochirurgiczny. Najczęściej jednak żadna z wyżej wymienionych metod nie pozwala na odtworzenie pełnej, utrzymującej się korekcji deformacji paznokcia.
Opis przypadku. U ośmioletniego chłopca doszło do amputacji całkowitej części paliczka dystalnego palca środkowego, rana została zaopatrzona pierwotnie szwami skórnymi. Około 4 lata później pacjent został przyjęty do kliniki z powodu wtórnej deformacji płytki paznokciowej typu „hook nail”, z zagięciem w kierunku dłoniowym i skośnym, która powodowała dolegliwości bólowe oraz defekt kosmetyczny. Badanie radiologiczne wykazało brak większości paliczka dystalnego.
Leczenie. Wykonano chirurgiczną rekonstrukcję ubytku paliczka dystalnego z wykorzystaniem przeszczepu kości z talerza biodrowego, ustabilizowanego dwoma drutami „K”. Ubytek skóry w obrębie opuszki palca został pokryty uszypułowanym płatem z okolicy kłębu kciuka. Płat został odcięty po około 4 tygodniach. Druty „K” zostały usunięte po 4 miesiącach.
Wyniki. Leczenie było dobrze tolerowane przez pacjenta, w trakcie leczenia nie wystąpiły powikłania. Przeszczep kości stanowił podparcie dla macierzy paznokcia podczas okresu gojenia. Uzyskano prawidłowy wzrost paznokcia oraz zadowalający efekt kosmetyczny. W trakcie około 2-letniej obserwacji pacjenta, doszło do niewielkiego odchylenia rotacyjnego płytki paznokciowej, co mogło być skutkiem częściowej resorpcji przeszczepu kostnego oraz wzrostu pacjenta. Dla pacjenta wynik końcowy leczenia jest satysfakcjonujący.
Wnioski. Całkowite oraz trwałe odtworzenie prawidłowej płytki paznokciowej i obrysu opuszki jest praktycznie nieosiągalne. W opisywanym przypadku klinicznym zastosowane leczenie pozwoliło na odtworzenie zadowalającego efektu zarówno funkcjonalnego jak i kosmetycznego.
Hook nail deformity is a common complication following fingertip amputations. Multi-tissue damages and partial and complete finger amputations are prevalent injuries among the pediatric population [ref]. Loss of distal bone support and palmar pulp tissue result in the volar curving of the nail bed, which may cause pain and aesthetic and functional problems [1-4].
Hook nail deformity in a pediatric population may also result in considerable anxiety to both young patients and their parents.
Infections, burns, displaced fractures of the terminal phalanx or tension on the nail bed after terminalization resulting in loss of distal bone support are other causes that may be followed by hook nail deformity .
Many surgical techniques such as “antenna procedure”, homodigital flaps, osteocutaneous flaps, composite toe grafts and distraction osteogenesis of the distal phalanx have been described for correction of nail deformity [3, 6-11].
However, none of them provides reliably good and persistent correction.
Description of the original approach to correcting hook nail deformity consisting of bone graft and local flap.
An 8-year-old boy sustained amputation of a part of the distal phalanx of the middle finger and underwent surgical closure of the wound. After 4 years, the patient was admitted to our Department due to hook nail deformity, which was occasionally painful, negatively influencing working with the keyboard and aesthetically unpleasing. The hook nail was curved volarly and obliquely. The radiographs showed a typical lack of the major part of the distal phalanx (Fig. 1).
Surgical reconstruction of the deficient distal phalanx was performed. The hooked nail was removed. The fingertip was opened just below the nail bed, and careful dissection was performed to preserve this structure. After shaping, the unicortical compound iliac bone graft was inserted into the remaining refreshed base of the distal phalanx and stabilized with two K wires through the distal interphalangeal (DIP) joint. Afterwards, a pedicled flap from the thenar was used in order to cover the fingertip defect (Fig. 2). The donor site of the flap was closed primarily.
Pedicle division was performed at around 4 weeks
(Fig. 3), after confirmation of satisfactory vascularization and exercises of metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints were started. „K” wires were removed after 3 months in an outpatient clinic after confirmation of bony union.
The procedure was well-tolerated by the patient, and no intra or postoperative problems or complications occurred. The bone graft united with the base of the distal phalanx and provided solid support for the nail bed during healing. Adequate growth and aesthetics of the nail was achieved (Fig. 4). Range of motion of the distal interphalangeal joint obtained by the patient was full extension and 80 flexion. Pain of the distal phalanx was eliminated, and daily life activities function improved. The patient was satisfied with the treatment. At 2 years follow-up, slight rotation of the nail was observed, which could have resulted from partial graft resorption and growth of the patient (Fig. 5).
Although perfect restoration of the nail bed length and pulp contour remains unobtainable, our result showed stable and aesthetically satisfactory correction of the hook nail deformity.
Hook nail deformity, resulting from the traumatic loss of bony or soft tissue support of the distal phalanx, may be avoided when treated appropriately at the time of the initial injury. The recommended treatment method is to remove the portion of the sterile matrix that extends past the remaining distal phalanx support . However, in the presented case, the patient was admitted to our department four years after sustaining an injury, with established deformity.
Numerous surgical procedures have been reported for hook nail deformity management [4, 6, 8, 9, 12].
The literature describes methods such as V-Y or oblique Flap , island flap , cross finger flap  or homodigital advancement flap , which provide covering of the defect and restoration of the pulp. Although the methods mentioned above provide relatively good outcomes, the lack of bone graft may be followed by a recurrence of the hook nail deformity  or shortening of the finger. On the other hand, more advanced techniques such as composite toe graft  or microsurgical nail reconstruction  require microsurgical experience, longer operative time and better compliance. They are also connected with donor site morbidity, which the patient often does not accept.
The “antenna procedure” described by Atasoy and colleagues consists of the release and elevation of the full thickness of the nail bed from the distal phalanx, followed by splinting with multiple “K” wires to support the correction . The created defect of the pulp is next reconstructed with a cross-finger flap. The authors reported improvement in the appearance and function of the injured finger. However, in most cases, some degree of hook nail deformity remained. In a few cases, a recurrence of hooking of the nail was observed. Moreover, Atasoy’s antenna procedure requires sacrificing the adjacent finger. It is necessary to close the cross- finger flap site utilizing a full-thickness graft. Also, it has been suggested that “K” wire splinting may be insufficient for distal phalanx support . This procedure is also inadequate for significant loss of the distal phalanx, as in our case.
Bakhach established the method consisting of nail matrix separation followed by its proximal reinsertion, also known as eponychial flap . A review of 30 cases based on the Bakhach procedure revealed satisfactory aesthetic results, with the restoration of almost entire length of the visible nail compared to uninjured contralateral digits. However, in all patients, the surgical procedure was performed acutely. No data on managing chronic deformities using this technique is available. Moreover, the presence of extensive scarring over the eponychium is considered a contraindication for the use of eponychial flap .
In the presented case, severe injury caused the loss of a major part of the distal phalanx. We assumed that when performing a soft-tissue augmentation procedure alone, without solid bone support, a recurrence of hooking would be inevitable. Moreover, contrary to a cross-finger flap, we restored the defect of the pulp using a pedicled flap from the thenar. As a result, sacrificing an adjacent finger or performing skin grafting was unnecessary. We achieved satisfactory correction of the hook nail deformity and a good pulp contour. During the 2-year follow-up, no recurrence of hook nail deformity was observed; however, a slight rotation of the nail occurred, possibly caused by the rapid growth of our adolescent patient and partial resorption of the graft. This resorption was also observed by Dumontier et al. when analysing 18 cases treated by the advancement of a homodigital island flap and bone graft in selected situations . This could be explained by covering the graft with a pedicled flap, which could provide adequate vascularity in the initial stage of graft incorporation.
Moreover, thenar flap with forced flexion position over 3-4 weeks and DIP transfixation for 3 months can be questioned as possibly resulting in joint stiffness, but this was not observed in our patient, who quickly regained full MP and PIP range of motion and near full in DIP joint.
Although perfect restoration of the nail bed length and pulp contour remains almost unobtainable, our result showed satisfactory and discomfort-free correction of the hook nail deformity.
We propose a technique of bone graft and regional pedicled flap for hook nail deformity correction with acceptable functional and aesthetic improvement. The presented method may be an alternative for hook nail surgical management to avoid more advanced, usually microsurgical techniques that imply donor site morbidity. However, the expectations and goals should be carefully discussed with the patient, taking into consideration the pros and cons of the presented approach.
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