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Influence of postoperative immobilization on tendon length after radiofrequency-induced shrinkage. An in vivo rabbit
Wolfgang Pötzl1, Kai-Axel Witt, Lars Hackenberg
1Department of Orthopaedic Surgery, University Hospital Münster, Münster, Germany.
Background:
Despite the widespread use of radiofrequency-induced shrinkage of collagenous tissues, there have been no animal studies on the effects of postoperative immobilization after such treatment.
Purpose:
To examine the effects of postoperative immobilization after radiofrequency energy treatment, with special emphasis on any tissue length increases.
Study Design:
Controlled laboratory study.
Methods:
The right patellar tendon of 60 New Zealand White rabbits was shrunk with a radiofrequency probe. Tendon length was measured intraoperatively before and after shrinkage and via radiographs immediately postoperatively and at 3, 6, and 9 weeks. Twenty rabbits were not immobilized, 20 were immobilized for 3 weeks, and 20 were immobilized for 6 weeks.
Results:
In the nonimmobilized limbs, the tendon length increased 34.9% at 3 weeks and another 2.5% at 6 weeks, versus 11.2% at 3 weeks and 6.6% at 6 weeks in the immobilized limbs. Ten of the 20 rabbits that were immobilized for 6 weeks were sacrificed at 9 weeks and were found to have a further length increase of 10.8%. At 9 weeks, the tendons of this group were no longer significantly shorter than the tendons from rabbits that had not been immobilized.
Conclusions:
Careful postoperative rehabilitation is imperative after radiofrequency-induced shrinkage. Without protection, exposure to normal physiologic loads places the shrunken tissue at risk of stretching out beyond the preshrinkage length.
Clinical Relevance:
Shrunken tissue is at risk of stretching out after radiofrequency-induced shrinkage.
