Microskills: The Soweto Knot
Updated: Jul 10
Penetrating injuries dominate at Bara,[1,2] and the thorax is the single most commonly involved body region. The intercostal chest drain (ICD) is therefore one of the most frequently performed procedures in the TEU,[2] and this high volume has bred innovation.
The procedure for inserting a surgical drain has become fairly standardised throughout the world: identify your triangle of safety, blunt dissect to the pleural space, and drain what needs draining. Whether you are managing a haemothorax, a pneumothorax, or the combination of both, the steps from incision to tube insertion follow a recognisable sequence that most trauma surgeons would agree on.
What's less standard is what happens after the drain goes in, or more accurately, what you do to stop it from coming back out. There are more ways of securing an ICD than there are surgeons, but everyone seems to have a different opinion on which is the best, and how you quantify the best. Is it dislodgement rate? Is it empyema rate? Is it scar cosmesis? Is it ease of later removal?
In our setting, dislodgement is a particular risk. About 1.4% of intercostal drains become dislodged [3] – and it’s a problem that’s easily preventable. The “Soweto knot” or “Jo'burg knot” is our unit’s choice, and it has been around for a while [4] – though seems to be “re-discovered” and “re-invented” in various forms every now and then.[5] Systematic reviews and cadaveric pig studies seem to show it’s the most robust of the common suture methods, and it’s about three times stronger than a purse string suture in particular.[6-9]
Because of the knot’s design, tension applied to the tube tightens the wound, reducing the danger that traction will result in dislodgement. The other benefit to the Soweto knot is in how it allows immediate closure of the wound after the suture is cut and the ICD is removed, theoretically reducing the risk of pneumothorax re-accumulation.
Note that the video above shows us using a horizontal mattress suture to initially close the thoracostomy incision. This is a variation described in the literature,[3,5] but the original technique described by Prof. Plani uses a vertical mattress suture.[4]
When removing the ICD, the suture should be cut just proximal to the knot. Once unwrapped, this leaves the two free ends for one clinician to grasp and keep tension on. This means that as another clinician removes the tube, and the patient forcibly exhales, the clinician holding the free ends of the suture material can pull the wound closed, immediately sealing the defect, and then use them to tie a knot to close it.
Legend has it that when applied correctly, a Soweto knot is secure enough that one could lift a patient clean off the bed by their drain. We do not recommend testing this hypothesis — our ethics committee would have questions, and the patient almost certainly would too.
Thank you to Dr Nick Chapman for providing his hands in the demonstration video above.
Dr Naeem Vallee is a general surgical registrar at the University of the Witwatersrand. He fell in love with surgery while working as an intern at Chris Hani Baragwanath in the Trauma Unit.
Naeem has a special interest in trauma and vascular surgery. He is also an avid barista and fountain pen collector.
References
[1] Bhana M, Fru P, Plani F. A long walk to freedom: the epidemiology of penetrating trauma in South Africa – analysis of 4,697 patients over a six-year period at Chris Hani Baragwanath Hospital. S Afr J Surg. 2022; 60(2):77-83.
[2] Chapman NG, Kinukawa R, Nudelman ER, Wineberg DL. The contemporary burden of major trauma in Soweto: a descriptive study from the resuscitation room of Chris Hani Baragwanath Academic Hospital. S Afr J Surg. 2026; in press.
[3] Ablett DJ, Navaratne L, Chua D, Streets CG, Tai NRM. The modified ‘Jo’burg’ technique for securing intercostal chest drains. J R Army Med Corps. 2017;163(5):319-23.
[4] Plani F. Securing intercostal drains in trauma surgical practice – how I do it. CME. 2004;22(7):388-390.
[5] Maritz D, McLauchlan C. A novel way to secure a chest drain. Ann R Coll Surg Engl. 2014;96(1):82.
[6] Wong C, Wright J, Siena FL, et al. What is the best way to secure a chest drain? A scoping review. J Intensive Care Soc. 2026;27(2):198-212.
[7] Fricke JJ, Schöbel T, Meißner R, et al. Modified Johannesburg technique sets the standard – superior biomechanical stability in chest tube fixation. Eur J Trauma Emerg Surg. 2026;52(1):27.
[8] Howes RJ, Calder A, Hollingsworth A, Jones A. The end for the ‘roman sandal’: observational study of methods of securing chest drains in a deployed military setting. J R Nav Med Serv. 2015;101(1):42-6.
[9] Ringel Y, Haberfeld O, Kremer R, et al. Intercostal chest drain fixation strength: comparison of techniques and sutures. BMJ Mil Health. 2021;167(4):248-50.
