# Establishing a best practice for the freeze-thaw cycle of cryopreservation to approximate living muscle, joint, and associated soft tissue properties in cadaveric upper limbs

## TL;DR

This study determines the optimal thawing time for fresh-frozen cadaveric upper limbs to simulate living tissue properties for surgical training.

## Contribution

The study establishes a best practice for thawing cadaveric limbs to approximate live tissue properties without damage.

## Key findings

- Limbs thawed for 2 hours achieved a flexibility score of 3/5, similar to healthy live limbs.
- Muscle biopsies showed no tissue damage in most samples taken up to 6 hours of thawing.
- Thawing for 2 hours after refrigeration allows 4 hours of effective surgical simulation.

## Abstract

Fresh-frozen cadavers are useful for surgical simulation and experimentation since they preserve many properties of live specimens, but achieving realistic physiological properties requires thawing that risks tissue damage.

Ten fresh-frozen cadaveric upper limbs were frozen at −17 °C, refrigerated at 4 °C for 48 h, then thawed at room temperature for 8 h. The core temperature of the limbs was measured hourly. Joint flexibility, durometric hardness, and shore hardness were measured every two hours. Four limbs had muscle biopsies acquired every 2 h.

The limbs were above freezing after about 1 h of thawing. The upper limbs achieved a flexibility score of 3/5 after 2 h of thawing, mimicking healthy live limbs. The limbs became softer and more pliable with more time thawing. Muscle biopsies showed no tissue damage in any samples taken at h 2 and 4 of thawing. Three limbs showed no tissue damage at h 6 or 8, either. One limb had biopsies at 6 and 8 h demonstrating moderate to severe tissue damage.

It was concluded that for ideal thawing, fresh-frozen cadaveric upper limbs should be thawed for 2 h after 48 h of refrigeration, permitting surgical simulation for 4 h after thawing, though potentially for 6 h.