Antenna Procedure for the Correction of Hook Nail Deformity

INTRODUCTION

Hook nail deformity may occur following traumatic amputation of the fingertip, especially if the loss is palmar oblique in orientation. Loss of the terminal part of the distal phalanx and palmar pulp tissue leaves the nail bed unsupported and results in a characteristic curvature of the nail plate as it grows out from normal proximal germinal matrix. Pulp tissue is deficient and the fingertip is often tight and painful with inadequate padding over the bone. The claw-like appearance of the fingertip can be aesthetically distressing.

Hook nail deformity can also follow loss of distal bone support from other causes such as infection, burns, displaced fracture of the terminal phalanx or tension on the nail bed after terminalization.

Many procedures have been described for correction of nail deformity. Some of these are complex procedures such as free vascularized tissue transfer from other digits (Endo et al., 1997) or composite grafting (Bubak et al., 1992). Simpler procedures often fail to completely correct hook nail deformity and there is a tendency towards recurrence of the defect. Bone grafts may be used for distal support but are associated with problems of resorption (Dumontier et al., 1995).

Atasoy and colleagues (1983) described the antenna procedure for the correction of hook nail deformity. This differs from previously described procedures in that the nail bed is splinted into a suitable position and then support is provided to keep it there.

Atasoy suggests that the three important aspects to this procedure are (1) to free tethered pulp; (2) to free tethered nail bed and splint it with longitudinal K-wires inserted into the terminal phalanx; (3) to reconstruct the pulp by covering the defect with a cross-finger flap.

Our aim was to assess the results of this procedure with regard to patient satisfaction, improvement in appearance (subjective and objective), and recurrence of deformity.

PATIENTS AND METHODS

A total of seven antenna procedures for the correction of hook nail deformity were performed between 1990 and 2000. Six procedures were for fingertip amputations and one for an electrical burn. Indications for surgical correction were pain, discomfort and cosmesis. Case notes and photographs were reviewed retrospectively. Four patients returned for clinical review.

RESULTS

The results are shown in Table 1. The mean follow-up was 3 years 4 months. All patients, including children, tolerated the procedure well. There were no major complications.

In all seven patients the deformity was noticeably improved in the opinion of the reviewer and patient (Figs 3–5). All patients stated that they were pleased with their result in that the appearance was improved and function was good. In those patients who were formally assessed two-point discrimination, pulp sensation and finger function were good.

In all fingers there was some residual deformity including shortening and flattening of the nail and a degree of contour defect of the pulp. In two cases there was some recurrence of hooking of the nail plate (Fig 3).

DISCUSSION

Numerous techniques have been described to address the problem of hook nail including V–Y flaps, cross-finger flaps, full thickness skin grafts, bone grafts, toe-nail bed graft, composite toe grafts and even microsurgical transfer (Atasoy et al., 1983; Bubak et al., 1992; Dumontier et al., 1995; Endo et al., 1997). For most procedures some improvement in appearance is described. Review data are, however, often limited, some techniques are complex and no procedure provides reliably good correction. Atasoy’s antenna procedure differs from other procedures in that it provides rigid support of the nail bed during healing. By the time the K-wires are removed it is suggested that the nail bed is supported in its new, more “normal” position.

Dumontier et al. (1995) highlight the difficulties of achieving and maintaining a correction of hooknail deformity. They used a similar procedure to the Atasoy technique incorporating elevation of the entire nail bed and matrix from the distal phalanx through a fishmouth incision. If the nail bed remained convex it was splinted with longitudinal K-wires for 3 weeks. The defect was filled by a homodigital island advancement flap and instead of removing the nail plate they favoured parallel transverse cuts so that it could remain as a splint. Using this technique they achieved good corrections in six of 18 cases and partial corrections in another six but recurrence had occurred in the remaining six at 31 month follow-up (Dumontier et al., 1995). Incomplete correction and recurrence of the deformity are problems and correction often results in a shortened nail and a contour defect of the pulp. Our results concur with those of Dumontier. The Dumontier team also believed that the greater the bone loss the worse the results, but this fact was not statistically significant in their study. We have not specifically addressed this variable in our follow-up but it is certainly a logical deduction. X-rays were available in three of our cases and, interestingly, did not concur with this opinion as one of the cases showing some recurrence of hooking had an almost complete distal phalanx and one with significant distal phalanx loss obtained a very satisfactory result (Fig 5).

Kumar and Satku (1993) showed by means of cadavaric dissection that the normal nail bed is entirely supported by the terminal phalanx. They believe that loss of terminal phalanx support of the nail therefore allows the development of hook nail deformity. This may be an oversimplification of the situation with tension in the pulp, due to scarring or loss of volume, being a factor as well.

Kumar and Satku suggest that the antenna procedure is conceptually flawed as it fails to bring in bony support to replace the loss of terminal phalanx (Kumar and Satku, 1993). This is not an unreasonable assumption but our results suggest that the improved pulp bulk due to the cross-finger flap is able to support the nail bed adequately. The factors at surgery which may assist this include elevation of the nail bed, release of the tethered pulp, maintenance of the corrected position of the bed and distal excision of nail bed matrix. A shorter, flatter and less curved nail is obtained with improved pulp contour.

Although perfect restoration of nail bed length and pulp contour remain elusive, our result show that stable improvement was achieved in spite of severe preoperative deformities. The procedure was well tolerated by the patients and they and their parents were well satisfied with the improvement in appearance.