Microsurgical practice on avulsed skin

A Super-Microsurgery Training Model: The Mouse Caudal Artery Anastomosis Model

Objective

To establish a simple and practical model for super-microsurgery training using the middle caudal arteries of Kunming mice.

Methods

A ⊔-shaped incision was made approximately 1 cm from the root of the tail in the mouse, and the skin, together with the subcutaneous tissue, was turned up into a rectangular shape to the opposite side with exposure of the mouse middle caudal artery and the accompanying veins. The artery was freed for approximately 1 cm in length. The middle caudal artery was cut transversely at the site, and then the severed middle caudal artery was anastomosed end-to-end using 12-0 microsutures in the order of 6, 12, 3, and 9 o'clock with four stitches.

Results

The mouse caudal artery had a constant anatomical location accompanied by a vein. The immediate postoperative patency after vascular anastomosis was 100% (15/15) in all mouse models, the postoperative patency was 100% (5/5), 80% (4/5), and 75% (3/4) at 24 h, 3 days, and 1 week postoperatively, respectively. The outer diameter of the mouse middle caudal artery was 0.2 ~ 0.3 (0.22 ± 0.03) mm. The vascular anastomosis time was 6.5 ~ 15 (11.0 ± 2.5) min.

Conclusion

The mouse middle caudal artery was superficially located and anatomically constant, making it easy to be located and exposed. The small size of the opening made it suitable for establishing a useful model for training in super-microsurgery vascular anastomoses.

Silicone-based simulation models for peripheral nerve microsurgery

BACKGROUND

There is a need for a peripheral nerve model on which surgeons-in-training can simulate the repair of nerve injuries at their own pace. Although practicing on animal models/cadavers is considered the "gold standard" of microsurgical training, the proposed model aims to provide a platform for improving the technical skills of surgical trainees prior to their practice on cadaver/animal models. In addition, this model has the potential to serve as a standardized test medium for assessing the skill sets of surgeons.

METHODS

Several formulations of silicone were utilized for the design and fabrication of a model which realizes the hierarchical structure of peripheral nerves. The mechanical properties were characterized via the Universal Testing Machine; the damage caused by the needle on the entry sites was assessed through scanning electron microscopy (SEM).

RESULTS

Mechanical properties of the formulations of silicone were tested to mimic human peripheral nerves. A formulation with 83.3 wt% silicone oil and 0.1 wt% cotton fiber was chosen to be used as nerve fascicles. Both 83.3 wt% silicone oil with cotton fiber and 66.6 wt% silicone oil without fiber provided a microsuturing response similar to that of epineurium at a wall thickness of 1 mm. SEM also confirmed that the entry of the needle did not introduce significant holes at the microsuturing sites.

CONCLUSIONS

The proposed peripheral nerve model mimicked human tissues mechanically and cosmetically, and a simulation of the repair of a fifth-degree nerve injury was achieved.

Pulsatile Perfused Porcine Coronary Arteries for Microvascular Training

Microsurgery is today an established technique in specialties such as plastic surgery, neurosurgery, and trauma surgery. However, specialized training is a prerequisite for mastering anastomosis of small-diameter vessels or coaptation of nerves in the operating room. The training should be as realistic as possible and thus, laboratory animals such as the rat are preferably used as a substitute. In an attempt to minimize the use of living animals without jeopardizing a realistic training setting, we developed a pulsatile perfused porcine coronary artery model for microsurgical education. The training model consists of a membrane pump that generates a pulsatile flow within a coronary artery of a porcine heart. The pump is commercially available with a dimension of approximately 130 x 100 x 60 mm and a weight of 190 g. The pump is energized by 220 B and the motor is run on a transformed power of approximately 12 V (range, 1.5-12 V). Different fluids from simple saline solution to theoretically whole blood can be used for perfusion. The membrane pump proved to be very reliable during microvascular training because of its convenient size and wide range of feed rate providing a very realistic training setting. A maximum fluid output of 850 mL/min can be achieved. The pump has a high acceptance in microsurgical trainees evaluated by questionnaires during several microsurgical courses. The pulsatile perfused porcine coronary artery system for microsurgical training enables the trainee to work under the most realistic training settings. It proved to be a valuable tool during microsurgical education, reducing the costs and sparing living laboratory animals. Thus, we can recommend this system to anyone who is involved in training and teaching microsurgical skills.

Non-vital, prosthetic, and virtual reality models of microsurgical training

Many microsurgical training models exist. These can be broadly classified into living and non-living. The latter type can be further sub-classified into non-vital, prosthetic, and virtual reality models. We review each model within these sub-groups with reference to the ideal properties of a training model. The most important attribute of any model is that the skills acquired from it must translate efficiently into microsurgical skill in the clinical situation. We believe that non-vital and prosthetic models are an important complement to living ones in training and maintaining the skills of all microsurgeons. As virtual reality technology improves, virtual models may succeed the rat as the microsurgical training tool of choice.

New model for microsurgical training and skills maintenance

PracticeRat (Sharpoint, Reading PA) is a system containing a simulation vein, artery and nerve, designed as an alternative to live animal use in microsurgical training. We find PracticeRat to be more expensive than living models. However, it does decrease animal usage and provides a very convenient opportunity to practice microsurgical techniques and procedures in a fairly realistic manner. Trainees can practice anytime, for any length of time, wherever microscopes are available. In this regard we find PracticeRat+ to be a useful addition to microsurgical training programs and an excellent tool for skills maintenance.