Purpose: Shrinkage of the elongated anterior cruciate ligament (ACL) and its grafts with radiofrequency
(RF) energy has become increasingly popular as an alternative to ACL reconstruction
in the field of knee surgery. Although there have been a few clinical studies on the
outcome and complications of RF shrinkage of the elongated ACL, there is a substantial
lack of in vivo basic science studies to evaluate the mechanical and histologic changes
of such treated tissue. Therefore, it was the aim of this study to simulate an ACL
elongation in an animal model, treat this pathology with RF shrinkage, and analyze
the mechanical and histologic changes at 6 months after initial treatment. Type of Study: Experimental in vivo animal study. Methods: A chronic elongation of the ACL was simulated in 16 mature female merino sheep. In
group A, no treatment was applied; in group B, RF shrinkage was used. For biomechanical
testing anteroposterior (AP) laxity was measured at time zero and 24 weeks. A load-to-failure
test was also performed at 24 weeks. For histologic analysis, cell number and crimp
pattern were measured by conventional histologic examination and the vascular status
by immunohistochemical histologic examination. Results: The initial reduction of AP laxity after RF shrinkage could not be maintained at
24 weeks. A significant reduction in ultimate load was found at 24 weeks in the RF-treated
group B compared with the untreated group A. At 24 weeks, an intensive process of
tendon remodeling was ongoing in the RF-treated group that differed substantially
from the untreated elongated ACLs and the intact ACL. Conclusions: The treatment of an elongated ACL with RF energy resulted in a significant impairment
of its ultimate load and induced a process of intensive remodeling that was not completed
at 24 weeks. Therefore, strong caution is warranted during the time of rehabilitation,
considering the impaired ligamentous structure. Clinical Relevance: This study provides insights into the consequences of RF shrinkage of the ACL that
will guide the clinician in the appropriate rehabilitation of patients and informs
of possible complications associated with this procedure.
Key Words
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Article info
Footnotes
Supported in part by research funds from the Humboldt-University of Berlin.
This paper was the recipient of the John Joyce Award at the Congress of the International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine, Auckland, New Zealand, March 10–14, 2003.
Identification
Copyright
© 2005 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.
