(A) Juncture of S2-3
(B) Juncture of S3-4
(C) Juncture of S4-5
(D) Juncture of the coccyx and sacrum
(E) Mid coccyx

The correct response is Option A.

The juncture of S2-3 is the highest level at which bony debridement can be performed without risking entry into the dural space. Extensive debridement in the dural space may damage the nerve plexuses of the sacrum and coccyx.

The conus medullaris, which is the terminal end of the neural portion of the spinal cord, lies at the level of L2. The cauda equina, or intravertebral portion of the nerves of the lower spine, continues on through the sacral canal to the coccyx, and the dural and subarachnoid sheaths terminate at the level of the second vertebral body. Vascular fibrofatty tissue surrounds the dura mater. The coccyx is formed by the fusion of four rudimentary vertebrae at the end of the spinal cord; it articulates with the caudal end of the sacrum.

References
1. Clemente CD, ed. Anatomy: A Regional Atlas of the Human Body. 2nd ed. Baltimore, Md: Urban & Schwarzenburg; 1981:494-500.
2. Netter FH. Atlas of Human Anatomy. Summit, NJ: Ciba-Geigy Corporation; 1989:19, 36-37, 122.

A 52-year-old man with quadriplegia has pressure ulcers of the left and right ischia after sitting in his wheelchair for prolonged periods. Physical examination of the ulcers shows involvement of the reticular dermis on the left and exposure of underlying muscle with purulent drainage on the right.

Which of the following is the correct clinical staging of these ulcers?

The correct response is Option B.

The National Pressure Sore Advisory Panel Consensus Development Conference has developed a system to classify pressure ulcers according to four stages:

Stage I The skin is intact, but has a red discoloration more than one hour after relief of pressure
Stage II There is a blister or other break in the dermis, with or without infection
Stage III There is subcutaneous destruction into the muscle, with or without infection
Stage IV There is bony or joint involvement, with or without infection

This 52-year-old quadriplegic man has pressure ulcers on both the left and right ischia. Because the pressure ulcer on the left involves the reticular dermis, it would be correctly classified as stage II. In contrast, the pressure ulcer on the right involves muscle and is thus classified as Stage III.

Staging systems for pressure ulcers address depth only and do not consider the presence of osteomyelitis, rates of recurrence, and the nutritional status and compliance of the patient. In addition, they do not necessarily reflect the underlying cause of the ulcer.

References
1. Colen SR. Pressure sores. In: McCarthy, JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;6:3797.
2. Mancoll JS, Phillips LG. Pressure sores. In: Aston SJ, Beasley RW, Thorne CH, eds. Grabb & Smith’s Plastic Surgery. 5th ed. Philadelphia, Pa: Lippincott-Raven; 1997:1083.

Which of the following is the primary advantage of using Integra (artificial skin) for coverage of full-thickness burns?

(A) Allowing for immediate use of cultured epithelial autografts
(B) Allowing for use of thinner autografts
(C) Avoidance of autografting
(D) Complete revascularization within seven days
(E) Prevention of fibroblast ingrowth into the dermal replacement layer

The correct response is Option B.

Integra, or artificial skin, is the most widely used skin substitute. It is a synthetic bilaminar membrane composed of a dermal matrix of porous bovine collagen cross-linked with shark-derived chondroitin-6-sulfate and covered by temporary Silastic epidermis. It does not contain neonatal fibroblasts or autologous keratinocytes. A two-stage application process is required; the initial stage is application of the dressing.

Following its application, the dermal matrix of the Integra dressing acts as a template, becoming infiltrated with host fibroblasts, endothelial cells, and inflammatory cells. The host collagen gradually replaces the bovine collagen during the healing process, and the silicone cover controls moisture loss and protects the wound. Adequate revascularization occurs within two to three weeks, at which time the superficial silicone layer will have sloughed off as a result of ingrowth through the collagen and glycosaminoglycan matrix. At this time, the Integra graft can be removed, and a thinner autograft, such as a very thin sheet of split-thickness skin graft, can be applied for durable coverage.

In addition to allowing for use of thinner autografts, advantages of Integra include immediate temporary coverage, more rapid healing of donor sites, and improved cosmesis.

Because the revascularization process is delayed, cultured epithelial autografts would fail to take if applied immediately because of the lack of vascularization in the wound bed.

Although Integra can be used to cover partial-thickness burns, it does not relieve the need for autografting over full-thickness burns.

As mentioned above, Integra is revascularized in two to three weeks, not within seven days, and allows for fibroblast ingrowth into the dermal replacement layer.

References
1. Dantzer E, Braye FM. Reconstructive surgery using an artificial dermis (Integra): results with 39 grafts. Br J Plast Surg. 2001;54:659-664.
2. Hansbrough JF, Franco ES. Skin replacements. Clin Plast Surg. 1998;25:407-423.
3. Jones I, Currie L, Martin R. A guide to biological skin substitutes. Br J Plast Surg. 2002;55:185-193.
4. Kao CC, Garner WL. Acute burns. Plast Reconstr Surg. 2000;105:2482-2492.
5. Stanton RA, Billmire DA. Skin resurfacing for the burned patient. Clin Plast Surg. 2002;29:29-51.