NewThe Purist Q is open. Ten questions on the anatomy of skin, free.Try it
AnatomyM8
The Purist QNew

Series 1: The Skin · Episode 9, not yet released

When Skin Fails

The Anatomy Behind Every Complication

23 minutes. 17 references, each checked at source.

Follow the podcast
Listen on SpotifyListen on Apple Podcasts

A wound at three weeks, the day the sutures come out and the day you tell the patient they are healed, has about twenty per cent of the tensile strength of the skin around it. At one week it has three per cent. It plateaus at eighty per cent at three months, and eighty per cent is the ceiling. Skin never gets back to a hundred.

The "fifty per cent at six weeks" figure everybody quotes cannot be sourced to primary literature, and this episode says so rather than passing it on.

Episode 9 of The Anatomy Purist is the bridge episode, from anatomy into pathology. Ischaemia as the common pathway, with Landis's capillary pressures so you can see exactly what a suture pulled to blanching is doing. Robson's bacterial threshold, and the beta-haemolytic streptococcal exception that is the other half of the answer. Haematoma versus seroma, distinct aetiology, sometimes identical on a scan, different management.

And negative pressure wound therapy, which does not simply increase perfusion. That claim came from porcine laser Doppler work now understood to be measuring an artefact; Kairinos measured perfusion *falling* by forty per cent at minus four hundred millimetres of mercury in human

Themes from this episode

Practice what you just heard

Two questions on the themes of this episode, free, marked as you go. Then one from the Vault on the same ground.

Question 1 · Applied

Approximately what proportion of normal skin tensile strength has a wound regained at three weeks?

Answer to see the explanation and the source.

Question 2 · Foundation

What are the four phases of wound healing, in order?

Answer to see the explanation and the source.

From the Vault, on the same theme

General Principles: Vascular, Lymphatic & Metameric Organisation · Purist Locked

After a run-over injury, a wide sheet of skin and subcutaneous fat has been stripped from the underlying fascia of a limb. In the emergency department the sheet is pink and bleeds from its cut edges, yet over the following days much of it dies. Which feature of the skin’s blood supply explains the deceptive early appearance?

  • ALongitudinal vessels running within the dermis carry the main flow in from the attached margins
  • BSympathetic overactivity after injury throws an anatomically intact supply into vasospasm
  • CVenous return fails first, and congestion rather than arterial ischaemia kills the sheet
  • DPerforating vessels rising from below are divided while the plexuses they feed still hold blood
  • EThe main vessels travel in the subcutaneous fat, which has moved with the skin

Unlock to see the answer

Unlock the Vault, £49
Try ten free questions from the seriesWhat the Vault is

References

  1. Gurtner GC, Werner S, Barrandon Y, Longaker MT. Wound repair and regeneration. Nature. 2008;453(7193):314-21. PMID: 18480812. doi:10.1038/nature07039
  2. Diegelmann RF, Evans MC. Wound healing: an overview of acute, fibrotic and delayed healing. Front Biosci. 2004;9:283-9. PMID: 14766366. doi:10.2741/1184
  3. Levenson SM, Geever EF, Crowley LV, Oates JF, Berard CW, Rosen H. The healing of rat skin wounds. Ann Surg. 1965;161(2):293-308. PMID: 14260029. doi:10.1097/00000658-196502000-00019
  4. Lindstedt E, Sandblom P. Wound healing in man: tensile strength of healing wounds in some patient groups. Ann Surg. 1975;181(6):842-6. PMID: 1138634. doi:10.1097/00000658-197506000-00014
  5. Robson MC. Wound infection: a failure of wound healing caused by an imbalance of bacteria. Surg Clin North Am. 1997;77(3):637-50. PMID: 9194884. doi:10.1016/s0039-6109(05)70572-7
  6. Orgill DP, Bayer LR. Negative pressure wound therapy: past, present and future. Int Wound J. 2013;10 Suppl 1:15-9. PMID: 24251839. doi:10.1111/iwj.12170
  7. Kairinos N, Solomons M, Hudson DA. Negative-pressure wound therapy I: the paradox of negative-pressure wound therapy. Plast Reconstr Surg. 2009;123(2):589-98. PMID: 19182617. doi:10.1097/PRS.0b013e3181956551
  8. Kairinos N, Voogd AM, Botha PH, Kotze T, Kahn D, Hudson DA, et al. Negative-pressure wound therapy II: negative-pressure wound therapy and increased perfusion. Just an illusion? Plast Reconstr Surg. 2009;123(2):601-12. PMID: 19182619. doi:10.1097/PRS.0b013e318196b97b
  9. Bovill E, Banwell PE, Teot L, Eriksson E, Song C, Mahoney J, et al. Topical negative pressure wound therapy: a review of its role and guidelines for its use in the management of acute wounds. Int Wound J. 2008;5(4):511-29. PMID: 18808432. doi:10.1111/j.1742-481X.2008.00437.x
  10. Ehrlich HP, Desmoulière A, Diegelmann RF, Cohen IK, Compton CC, Garner WL, et al. Morphological and immunochemical differences between keloid and hypertrophic scar. Am J Pathol. 1994;145(1):105-13. PMID: 8030742.
  11. Friedman DW, Boyd CD, Mackenzie JW, Norton P, Olson RM, Deak SB. Regulation of collagen gene expression in keloids and hypertrophic scars. J Surg Res. 1993;55(2):214-22. PMID: 8412102. doi:10.1006/jsre.1993.1132
  12. Huang C, Ogawa R. Fibroproliferative disorders and their mechanobiology. Connect Tissue Res. 2012;53(3):187-96. PMID: 22329637. doi:10.3109/03008207.2011.642035
  13. Mustoe TA, Cooter RD, Gold MH, Hobbs FDR, Ramelet AA, Shakespeare PG, et al. International clinical recommendations on scar management. Plast Reconstr Surg. 2002;110(2):560-71. PMID: 12142678. doi:10.1097/00006534-200208000-00031
  14. Leventhal D, Furr M, Reiter D. Treatment of keloids and hypertrophic scars: a meta-analysis and review of the literature. Arch Facial Plast Surg. 2006;8(6):362-8. PMID: 17116782. doi:10.1001/archfaci.8.6.362
  15. Lee JW, Seol KH. Adjuvant radiotherapy after surgical excision in keloids. Medicina (Kaunas). 2021;57(7):730. PMID: 34357011. doi:10.3390/medicina57070730
  16. Landis EM. Micro-injection studies of capillary blood pressure in human skin. Heart. 1930;15:209-28. [Predates MEDLINE indexing; no PMID available. Cited for the classical human skin capillary pressure measurements only.]
  17. Hypertrophic Scarring and Keloids. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. Bookshelf ID: NBK537058. [Secondary source; cited for site distribution and clinical course only.]
Episode 8: The HypodermisEpisode 10: Skin Grafts Part One
All episodes

Before you go

Tell us how this one landed

What worked, what you had to replay, and what you would like covered next. Requests are the main way the running order gets decided.

Send feedbackReport an error in this episode