Kurt P. Spindler, MD, Todd A. Warren, ACNP, and Eric C. McCarty, MD
Objective:
Ice and cryotherapy devices are ubiquitous in treatment of knee injuries; however,
no studies in normal or injured knees, in the absence of surgery, have evaluated
if intraarticular (IA) temperature changes. This is the first evaluation of
IA knee temperature comparing ice vs cryotherapy device in normal knees during
and after treatment.
Methods:
After IRB approval and consent, thermocouple probes were placed via 18G needle
intraarticularly in the suprapatellar pouch (SP) and on the skin of right and
left knees in twelve normal subjects. Treatment was crushed ice in a plastic
bag secured by plastic wrap applied to the anterior aspect of one knee with
a cryotherapy device (Cryocuff“) applied to the anterior aspect of the
contralateral knee. Both knees were treated for one hour, then both methods
of cryotherapy were removed for the second hour. Temperatures were simultaneously
recorded every minute for a total of two hours. Subjects were asked at six points
during the study to indicate discomfort levels of both knees through the use
of a 10cm visual analog pain scale (VAS).
Results:
As expected, ice significantly lowered skin temperature vs cryotherapy device
(30, 60, 90 min p<0.001) (see Table). IA temperatures were significantly
lowered from baseline in both groups with treatment. However, ice dropped the
temperature significantly greater than cryotherapy device at 60*, 90*, 120**
min. By VAS pain scores ice was more painful at 30*** and 60* min. Pain was
inversely correlated with IA temperature in the ice group at 120 minutes (rho=-0.65,
p=0.02).
Conclusions:
Both methods of cryotherapy showed significant declines in skin and intraarticular
temperatures in healthy knees. Ice produced significantly lower temperatures
and higher pain scores than the cryotherapy device. The increased pain scores,
however, are only clinically meaningful at 60 min (difference 2.4). Further,
pain was inversely correlated with IA temperature in the ice group. We hypothesize
a critical pain threshold may exist within the normal knee.
| |
0 Minutes |
30
Minutes |
60
Minutes |
90
Minutes |
120
Minutes |
|
Ice Skin (°C+/-SD) |
29.5 (1.0) |
8.7 (2.2) |
32.8 (1.0) |
17.0 (3.3) |
23.6 (2.4) |
|
Cryo Skin (°C+/-SD) |
29.8 (0.8) |
15.0 (1.9) |
13.1 (1.6) |
21.6 (1.5) |
25.1 (1.1) |
|
Ice IA (°C+/-SD) |
33.6 (1.0) |
29.6 (3.1) |
20.1* (3.8) |
18.2* (2.7) |
22.6** (3.2) |
|
Cryo IA (°C+/-SD) |
33.6 (0.8) |
30.9 (2.0) |
25.7 (2.3) |
23.7 (1.5) |
25.3 (1.2) |
|
VAS Ice/Cuff |
1.5/1.6 |
2.3***/1.4 |
4.0*/1.6 |
|
0.1/0.3 |
*p<0.001 **p=0.013 ***p=0.01