https://orcid.org/0000-0003-4690-1712
Introduction
Surgery requires more attention to technical details and craftsmanship than other medical disciplines1. The systematic 360° twist of the needle holder each time a stitch is passed in a continuous suture avoids curling of the thread as the suture advances. During surgical teaching, most trainees were found to be unaware of this, and the same was noticed with some more senior surgeons.
Methods
The question of applying a 360° twist to the needle holder when performing a continuous suture was approached from the following perspectives. First, the issue and the mechanical principle behind it were described. Then, a search of the medical literature (MEDLINE) and online videos (Google) was undertaken on the technique of continuous sutures, with special focus on whether a twist was explicitly taught or applied. The first 20 video tutorials on the internet that could be found using the term ‘continuous suture’ were analysed. The list of the websites consulted is included in Table S1. Finally, the authors sent a video (Video 1) and an online questionnaire to surgeons of different specialties in Switzerland and abroad, enquiring about their knowledge of the technique, how it was learnt, and if they taught it routinely (Table S2).
Results
Description of the issue
When performing a continuous suture (such as closing the abdominal fascia with a loop of polydioxanone), torsional tension building up in the thread can be observed. Stitch after stitch, the thread tends to coil, and small false knots are created. If pulled through, this may traumatize the surrounding tissues. The suture can indeed be guided to run smoothly, but this requires the assistant or the surgeon to accompany the thread to ensure even apposition [Fig. 1 and Video 1]. On the other hand, when the needle holder is twisted each time the suture is passed (in a clockwise direction, if the suture is done from right to left) no torsional force builds up, and the thread falls down neatly, practically without the help of the assistant.
Examples of sutures with and without the Cambridge twist
Drawing of a suture without the Cambridge twist, showing twisting and curling of the thread along the running suture, and drawing of a suture after using the Cambridge twist, showing the thread falling down neatly, avoiding curls and irregularities along the running suture.
The Cambridge Twist is thoroughly explained in the video file accessible by clicking on the illustration above
Mechanics of a running suture
The geometry of a running suture, such as one used for closing the abdominal fascia, corresponds to that of a helix whose radius is determined by the stitch bite (distance between the wound margin and the stitch entry/exit point), while the step is the distance between two stitches. To perform an even suture, the whole thread should follow the helix trajectory with the needle constantly turning around the wound breach, entering one side and exiting the other side of the wound. In other words, the needle should always point in the direction of the trajectory. This means that during the in–out step the needle must point towards the ‘out’ side of the wound, whereas during the out–in step it should point towards the ‘in’ side of the wound. If the needle holder is not twisted, the tip of the needle still follows the helix trajectory, whereas the rest of the thread does not. This results in the creation of a new helix going in the opposite direction, because, when the thread is pulled, the new helix twists it in the opposite direction to the original one. In addition, when a loop suture is used, the threads of the loop then continue to wrap around each other during each stitch step.
Tutorials
No video explaining the technique of the twist could be found. Interestingly, in video 2 on the list (Table S1), the recommendation is made to ‘rotate the needle driver in your hand’ simply as a way of avoiding the use of tissue forceps when taking the needle out of the skin. Moreover, in videos 4 and 7, the observer can see the curls that could have been avoided had the twist been used.
Survey
152 questionnaires were sent, with 53 (response rate of 34.9 per cent). The questionnaires were completed by surgeons from different specialties and countries, and revealed that only 29 of 53 surgeons (55 per cent) knew and used the technique, and 72 per cent of them learnt it from their mentors. Half of the surgeons interviewed were also teaching it (27 of 53, 51 per cent). However, none of them were aware of a name for the technique (apart from 7 who named it after the corresponding author, from whom they had learnt it) (Table S2). Several senior colleagues also expressed their amusement at having ignored this simple point for such a long time.
Discussion
The use of the needle holder twist allows continuous sutures, ranging from simple skin or fascial closures to the more complex anastomoses, to run more smoothly. The results from the survey and literature search support the impression that the principle is seldom applied and taught. Yet, the curling of a thread in continuous suturing should be common knowledge as it also applies to other principles in daily life, for example when rolling up an electrical wire (such as the charger of a mobile phone, although in this case the relative stiffness of the wire makes the problem of curling more evident. In the nautical world, the coiling of ropes is avoided by rolling them up each time by alternating a twist with a countertwist so that they unfold properly when thrown.
No reference to this manoeuvre could be found in surgical literature. Previous investigations2–4 have shown that twisting the suture diminishes its tensile strength, but the authors of the publications suggest freeing the needle at regular intervals, rather than applying the twist; this solution is as effective in unfolding the thread, but is less ergonomic.
A quantifiable clinical advantage of applying the twist would be desirable, but difficult to demonstrate. This is because the final result of a suture without the twist is rendered equivalent by the small corrective actions that are performed to mitigate its absence (as shown in the video and in the internet tutorials). However, as the focus of the present study is ergonomics, and the pleasure that can be derived from respecting the sense of things, a more qualitative and visual approach can reasonably be offered.
This technique was named the ‘Cambridge twist’ as a tribute to the Cambridge Surgical Registrar Rotation where it was most likely picked up by the corresponding author. Indeed, the mentors in the rotation insisted on ‘palming’ the needle holder, a technique that—as well as allowing greater freedom to direct the needle by freeing the wrist—renders the twist easy and intuitive to apply.
Acknowledgements
L.F. and S.G.P. contributed equally to this study. The authors thank S. R. Large and W. G. Everett, from the Cambridge Registrar Rotation, for their commitment to surgical teaching and for granting the authors permission to write a technical note on a procedure that was probably learnt from them in the late 1980s; and M. Arigoni MD, for his contribution to the section on the mechanics of a running suture.
Disclosure. The authors declare no conflict of interest.
Supplementary material
Supplementary material is available at BJS online.
References
