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NAIL ANATOMY

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SUMMARY

  • Nail procedures are is frequently performed for diagnostic and reconstructive purposes.

  • A detailed understanding of nail anatomy and the implications of damage to specific areas of nail anatomy are a prerequisite for performing nail surgery.

  • Visualization of the nail unit is required for surgical intervention; therefore, tourniquets are used for many nail procedures.

image Beginner Tips

  • Ensure that the dermatopathology laboratory has experience with handling nail specimens.

  • Examination of the free edge of the nail allows the clinician to determine whether the disorder originates in the proximal matrix (if the pathology is on the outer surface of the nail plate) or in the distal matrix (if the pathology is on the inner surface of the nail plate).

  • A 15-minute dilute chlorhexidine soak may help limit the risk of infection.

image Expert Tips

  • The distal digital (wing) block is faster and safer than a proximal block.

  • The main indication for matrix biopsy is longitudinal melanonychia.

  • Because the proximal nail matrix gives rise to the upper part of the nail plate, biopsies in this area are more likely to induce surface dystrophy or nail scarring.

  • Tangential shave biopsy is highly effective for wide pigmented lesions of the matrix.

image Don’t Forget!

  • When possible, a partial nail avulsion is preferred to complete nail avulsion.

  • Matrixectomy is faster, easier, and more comfortable when performed in a chemical, rather than surgical, fashion.

  • Nail bed biopsies should be oriented longitudinally; matrix biopsies should be oriented transversely.

image Pitfalls and Cautions

  • A rare complication of the transthecal block is injury to the flexor tendon that can result in scar or trigger finger.

  • For moderate bleeding, oxidized cellulose or calcium alginate dressings work nicely; for severe postoperative bleeding, injection of some anesthetic (0.5 mL) in a wing block fashion will act as a volumetric tourniquet (anesthetic tamponade of the nail unit) until clotting occurs.

  • Postoperative dysesthesia after nail surgery is common.

image Patient Education Points

  • Describing the anatomy of the nail unit, the usual rate of nail growth and the patient’s specific surgery prepares the patient for a postoperative course that meets their expectations. Preoperative discussion should also include a discussion of risks including pain, infection, bleeding, scar, nerve damage, nondiagnostic biopsy, and permanent nail dystrophy.

  • If surgery is to be performed on a toenail, the patient should be advised to bring footwear with adequate space to accommodate the postoperative dressing and a driver to escort them home safely. Elevation of the surgically manipulated limb is mandatory in order to limit postoperative pain and edema.

image Billing Pearls

  • Nail biopsy is coded using 1175.

  • Avulsion is coded using 11730.

  • Graft repair is coded using 11762.

  • Lateral wedge resection is coded using 11765.

  • Excision for onychocryptosis or onychogryphosis is coded using 11750.

INTRODUCTION

The nail unit is a complex anatomic structure that is ...

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