title: Electrothermal shrinkage reduces laxity but alters creep behavior in a lapine ligament model.
abstract: Thermal denaturation of collagen in ligament tissue has the potential to enhance arthroscopic shoulder stabilization. Previous studies have shown that laser energy produces significant capsular shortening without alteration of viscoelastic properties, but little information is available on the effects of radio frequency electrothermal energy. We assessed the acute effects of radio frequency shrinkage with use of the lapine medial collateral ligament model, in which the tibial insertion was shifted proximally to produce abnormal laxity. Thermal treatment resulted in restoration of laxity from 3.33 +/- 0.25 mm to 0.66 +/- 0.31 mm, which was not significantly different from medial collateral ligaments replaced anatomically (0.50 +/- 0.34 mm). When tested at 4.1 megapascals, cyclic and static creep strains were increased twofold to threefold in thermally-treated ligaments (P <.01), and partial failure occurred in 2 of 8 cases. We conclude that radio frequency electrothermal shrinkage is effective at reducing laxity but significantly alters viscoelastic properties, posing a risk of recurrent stretching-out at "physiological" loads.
authors.affiliation: McCaig Centre for Joint Injury and Arthritis Research, University of Calgary, Alberta, Canada. andrew.wallace@ic.ac.uk
authors.forename: A L
authors.initials: AL
authors.lastname: Wallace
authors.forename: R M
authors.initials: RM
authors.lastname: Hollinshead
authors.forename: C B
authors.initials: CB
authors.lastname: Frank
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001182:Arthroscopy / Q000379:methods*; D003094:Collagen / Q000737:chemistry; D017885:Collateral Ligaments / Q000503:physiopathology*; D005260:Female; D006358:Hot Temperature; D007593:Joint Instability; D007719:Knee Joint / Q000503:physiopathology*; D007834:Lasers; D023421:Models, Animal; D011336:Probability; D011817:Rabbits; D011897:Random Allocation; D012680:Sensitivity and Specificity
chemical_list: D003094:Collagen