Transitioning from Microsurgery to Supermicrosurgery: The Recurrent Ulnar Artery Model

Supermicrosurgery refers to a technique of dissection and anastomosis of vessels smaller than 0.8 mm.¹ The technique is widely regarded as the natural evolution of microsurgery, as our preoperative planning and imaging improve, instruments become more precise, and microscopes more advanced.¹

To date, supermicrosurgery technique has been employed to treat distal finger amputations and lymphoedema, and allows for perforator-to-perforator reconstructive solutions.² However, its true potential and uptake may only be reached through more extensive and innovative training solutions, developing the surgeon’s fine motor skills and precision in anastomosis.³

Simulated training models have been shown to be effective in developing both microsurgical and supermicrosurgical skills.⁴ The authors aimed to develop a cheap and novel training model to enable a smooth transition from microsurgery to supermicrosurgery technique by facilitating both skill transfer and acquisition, without the need of supermicrosurgery instruments.

The recurrent ulnar artery model provides an excellent opportunity to develop both microsurgery and supermicrosurgery skill (See Video [online], which shows a demonstration of the recurrent ulnar artery chicken wing microsurgical model in practice). This is an ex-vivo model using a chicken wing, which is based on the ulnar artery and its side-branch, the recurrent ulnar artery. The lead author (R.Y.K.) of this video article dissected 20 chicken wing models over a 2-month period, and performed 20 microsurgical and 40 supermicrosurgical anastomoses. Standard microsurgery instruments (compromising a needle-holder, curved micro-scissors, jeweler’s forceps, and a vessel dilator), a table-top operating microscope, and 10-0 S&T Nylon sutures were utilized.

Video 1. displays the supermicrosurgery training model.

Download video file ^{(89.3MB, mp4)}

The recurrent ulnar artery was found at the first knuckle of the chicken wing in all 20 specimens. Twenty anastomoses were performed end-to-end at the ulnar artery, with a mean vessel diameter of 1 mm. Twenty anastomoses were performed end-to-side between the recurrent ulnar artery and ulnar artery, with a mean vessel diameter of 0.7 mm. Finally, 20 anastomoses of the recurrent ulnar artery were performed end-to-end, with a mean vessel diameter of 0.4 mm. The mean diameter of the ulnar artery was found to be 1 mm, and the recurrent ulnar artery to be 0.4 mm across all 20 dissections. The total cost of the training model was 22 pence GBP (or 27 cents USD).

The recurrent ulnar artery chicken wing model provides a consistent, easily dissected and cheap solution to develop microsurgery and supermicrosurgery skills. It allows for an effective transition from anastomoses of greater than 0.8 mm, to those between 0.4–0.7mm in a graduated approach and within the same training setting and session, differentiating it from other training models.^4,5 It is, however, limited by its inherent ex-vivo nature and inability to assess real-time flow. Although it does not require specific supermicrosurgery instrumentation, it does need higher magnifications of up to 45× through a tabletop microscope. Future research is needed to validate the model, assess flow through anastomotic repairs, and focus on the learning curve assessment.