Dissipation of heat during polymerization of acrylics used for external skeletal fixator connecting bars.
OBJECTIVE
To determine the amount of heat conducted by transfixation intramedullary pins (IP) and Kirschner wires (KW) during polymerization of acrylics used for external skeletal fixator (ESF) connecting bars.


METHODS
Thermal conduction was measured using thermistors applied to IP and KW surfaces during the polymerization phase of acrylics.


METHODS
Type II ESF were created from IP or KW placed into wooden dowels and plastic tubing used to create connecting bars filled with one of two types of acrylic (Acrylic Pin External Fixation System or Technovit, Jorgensen Laboratories, Loveland, CO). Thermistors were positioned on the acrylic column surface and on IP or KW surfaces 5 or 10 mm from the acrylic column. Five ESF test groups were created. The maximum temperature (Tmax) of the acrylic column (Tmax-A), IP (Tmax-IP), KW (Tmax-KW), and duration that Tmax-IP or Tmax-KW remained greater than or equal to 55 degrees C were calculated.


RESULTS
All IP and KW thermistors placed 5 mm from acrylic columns reached mean temperatures greater than 50 degrees C and had peak temperature ranges greater than 55 degrees C compared with all IP and KW thermistors placed 10 mm from the acrylic columns in all groups. Thermistors placed 5 mm from the acrylic column in two groups maintained temperatures greater than 55 degrees C for greater than or equal to 0.5 minute.


CONCLUSIONS
Acrylic columns positioned 5 mm from a thermistor on a IP or KW had the potential to reach or exceed temperatures that have been reported to cause thermal necrosis of tissues.


CONCLUSIONS
Acrylic Pin External Fixation System or Technovit acrylic connecting bars used in ESF designs have the potential to cause thermal injury to soft and bony tissue by thermal conduction along transfixation pins or wires.
Martinez
S A
SA
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing 48824-1314, USA.
Arnoczky
S P
SP
Flo
G L
GL
Brinker
W O
WO
D000180:Acrylic Resins / Q000737:chemistry*; D000818:Animals; D001842:Bone and Bones / Q000473:pathology; D016267:External Fixators / Q000009:adverse effects / Q000662:veterinary*; D005592:Fracture Fixation / Q000009:adverse effects / Q000662:veterinary*; D006361:Heating / Q000009:adverse effects*; D009336:Necrosis; D009985:Orthopedics / Q000662:veterinary*; D011108:Polymers; D017695:Soft Tissue Injuries / Q000473:pathology; D013814:Thermal Conductivity
D000180:Acrylic Resins; D011108:Polymers