Wednesday, May 7, 2008

Dermatomes

dermatome /der·ma·tome/ (der´mah-tom)

1. an instrument for cutting thin skin slices for grafting.

2. the area of skin supplied with afferent nerve fibers by a single posterior spinal root.

3. the lateral part of an embryonic somite.

It's the first definition that I will be discussing.

Padgett invented the first dermatome in 1939. This one was a drum dermatome and was manually operated. It was a surgical instrument for easily removing large flaps of skin of a prescribed depth. This helped move skin grafting to common practice from a miraculous one.

Today dermatomes can be operated manually, air-powered, or electrically. Many are named after their inventors. There are what I would consider three main types:

Blade dermatomes

  • These provides rapid harvest of large grafts of uniform thickness. These may be air powered, electric, or manually operated.
  • All of these harvest by the same mechanism: a rapidly oscillating side-to-side blade is advanced over the skin with thickness and width settings adjusted by the surgeon.
  • Commonly used dermatomes include the Castroviejo, Reese, Padgett-Hood, Brown, Davol-Simon, and Zimmer (photo credit)
  • When using the air or electric powered dermatomes, the operating surgeon must be familiar with the installation of the blade and how to adjust the setting for graft thickness and must check these before operating the device. There is a correct and an incorrect orientation of the blade, and the two may easily be confused.
  • Insertion of a No. 15 blade scalpel simulates a thickness of 0.015 inches and can be used to check that thickness settings are uniform and correct. After the blade orientation, width guard and depth setting are confirmed, and harvesting may begin.

Drum dermatomes

  • Drum dermatomes are less frequently used today but are available for specialized grafting needs.
  • On these instruments, the oscillating blade is manually powered as the drum is rolled over the skin surface. These dermatomes can be used to harvest broad sheets of skin of exacting thickness.
  • They are useful when the donor site is irregular, with a convexity, concavity, or bony prominence (neck, flank, buttock), because the skin to be harvested is first made adherent to the drum with a special glue or adhesive tape.
  • These dermatomes also allow precise irregular patterns to be harvested by varying the pattern of adhesive applied to the skin and drum.
  • Disadvantages include the risk of injury to operating personnel by the swinging blade, the need to use flammable agents such as acetone or ether to cleanse the donor site and remove surface oils to ensure secure adhesion of the skin to the dermatome drum, and greater technical expertise required to safely and effectively operate these devices.
  • Reese and Padgett-Hood (photo credit) are examples of this type. Check out the 5th reference article.

Free-hand Knives

  • Called knives and not dermatomes, these still fit the definition. Examples include the Humby knife (photo credit), Weck blade, and Blair knife.
  • The disadvantages include grafts with irregular edges and varying thicknesses. As with the drum dermatomes, greater technical expertise is necessary, and graft quality tends to be operator dependent.
  • Check out this link on "preparing a Humby knife"

REFERENCES

1. Hand Knife Versus Powered Dermatome: Current Opinions, Practices, and Evidence; Annals of Plastic Surgery. 57(1):77-79, July 2006; Tehrani, Hamid MBBS, MRCSEd; Lindford, Andrew MBBS, MRCSEd; Logan, Andrew M. FRCS (abstract online)

2. Skin, Grafts; eMedicine Article, Feb 17, 2006; Don Revis Jr MD and Michael Seagle MD

3. Applying Split-Thickness Skin Grafts: A Step-by-Step Clinical Guide and Nursing Implications; Ostomy/Wound Management , Volume 47, Issue 11, November 2001 , Pages: 20 - 26;

4. History of Skin Grafting; Brown University Online Article

5. Grafting of Skin: Advantages of the Padgett Dermatome; Calif West Med. 1942 July; 57(1): 16–18; George Warren Pierce

5 comments:

Øystein said...

Interesting. I saw a blade dermatome in action last week. It was used to graft skin from the thigh to cover a defect on the shin after resection of a sarcoma.

A blade dermatome actually resembles the Norwegian cheese slicer, pictured here, which of course makes for lots of jokes.

rlbates said...

They remind me of the old straight razor

Dean said...

I could only read so much of this one. I kept thinking, "ouch, ouch, ouch..." :)

I'm not overly squeamish, but I don't think I could ever be a surgeon.

SeaSpray said...

Hi Ramona -interesting although I admit made me a little squeamish...the idea of shaving skin. I was also struck by the ingenuity of creating such an instrument and how precise it and the surgeon must be.

I hope you don't mind that I linked you and the image of surgery blog to my blog. Fascinating site!

rlbates said...

Sorry, Dean.

Seaspray, I don't mind at all. Am flattered actually.