Axillary nerve temperatures during radiofrequency capsulorrhaphy of the shoulder.
OBJECTIVE
The purpose of this study was to determine the temperatures along the course of the axillary nerve during radiofrequency (RF) capsulorrhaphy of the shoulder in a cadaver model. The hypothesis of this project was that temperatures capable of damaging neural tissue would be recorded during simulated RF capsulorrhaphy.


METHODS
Basic science evaluation.


METHODS
This study used 9 fresh-frozen cadaver shoulder capsules removed en bloc along with the underlying axillary nerve and soft tissue. The axillary nerve was instrumented with 4 thermocouples placed along the course of the nerve (2 thermocouples anterior and 2 posterior to the 6 o'clock position, spaced 7 mm apart). Each of the specimens underwent RF thermal capsulorrhaphy during which the temperature at each of the thermocouple positions was continuously recorded.


RESULTS
The average of the maximum temperature at each of the 4 positions measured along the course of the axillary nerve were 52.2 +/- 18.0 degrees C at the most anterior place probed, 45.8 +/- 5.44 degrees C (mid anterior), 44.5 +/- 8.7 degrees C (mid posterior), and 42.8 +/- 10.1 degrees C at the most posteriorly positioned probe. Two specimens had a maximum temperature greater than the 67 degrees C set point of the device, and 7 specimens had a maximum temperature greater than 45 degrees C in at least 1 thermocouple position.


CONCLUSIONS
This study shows that heating of the axillary nerve can occur during RF capsular shrinkage of the shoulder and may potentially reach levels that can damage neural tissue.
Gryler
E C
EC
Department of Orthopedics, the University of Utah Health Sciences Center, Salt Lake City, Utah 84132, U.S.A. patrick.greis@hsc.utah.edu
Greis
P E
PE
Burks
R T
RT
West
J
J
D001831:Body Temperature; D002056:Burns / Q000209:etiology / Q000517:prevention & control; D002102:Cadaver; D017115:Catheter Ablation; D004564:Electrocoagulation / Q000009:adverse effects; D006801:Humans; D017746:Joint Capsule / Q000473:pathology* / Q000601:surgery*; D059348:Peripheral Nerve Injuries; D010525:Peripheral Nerves / Q000473:pathology* / Q000503:physiopathology*; D012785:Shoulder Joint / Q000294:innervation*; D013817:Thermography