Friday, March 2, 2001
Twenty subjects (13 males, 7 females) diagnosed with unilateral glenohumeral instability, were treated with monopolar radiofrequency thermal capsulorraphy. Subjects were bilaterally tested 6-24 months (11.90 ± 5.65 months) following surgery. Each subject's ability to actively reproduce joint positions (ARJP) and reproduce paths of motion (RPM) were measured with an electromagnetic tracking device. Passive reproduction of joint positions (PRJP) and threshold to detect passive motion (TTDPM) were measured with a proprioception testing device. Function was quantified with the Shoulder Rating Questionnaire (SRQ).
Statistical analysis revealed a significant ARJP limb by direction interaction (p=.005) indicating that reproduction error was less with the involved limb moving into 90 degree abduction-external rotation, compared to the uninvolved limb. No difference existed moving into ADIR between limbs. No significant interactions were present for TTDPM, PRJP or RPM.
The SRQ indicates that the subjects returned to near normal function (91.86/100 ± 5.38 points) at the time of testing. Embedded within the triple helix collagenous structure of the glenohumeral joint capsule are mechanoreceptors that provide proprioceptive input to the central nervous system.
Application of thermal energy, whether with laser or radiofrequency energy, causes the helix structure to denature, which leads to the capsular shrinkage phenomenon. Accompanying this denaturation, it is suggested that the mechanoreceptors are also altered leading to deficits in proprioception. The results from our study do not support our hypothesis of proprioception and functional deficits from the thermal treatment, say the investigators. They include Joseph B. Myers, MA, Pittsburgh, Pa.; Scott M. Lephart, PhD, Pittsburgh, Pa.; James P. Bradley, MD, Pittsburgh, Pa.; and Freddie H. Fu, MD, Pittsburgh, Pa.
|2001 Academy News March 2 Index A|
Last modified 02/March/2001 by IS