title: The effect of postoperative immobilization on the healing of radiofrequency heat probe modified tissue: assessment of tissue length, stiffness, and morphology.
abstract: The effect of postoperative immobilization on the length, stiffness, and structure of connective tissue after radiofrequency probe shrinkage was examined in a rabbit patellar tendon model. Tendon lengths were measured before, immediately following, and 2, 4, and 8 weeks following heat application, with the contralateral tendon as a control. The animals were randomly assigned to three groups. In Group I, the controls, the animals were allowed free caged activity for 8 weeks. In Groups II and III, the experimental limb was immobilized at 15 degrees of knee flexion for 2 and 4 weeks, respectively, after which the animals were allowed 6 and 4 weeks of free caged activity. Changes in tendon length, stiffness, and cross-sectional area were compared using repeated measures ANOVA and differences between groups examined using Tukey's post-hoc analysis. Patellar tendon lengths were increased in all 3 groups at 8 weeks (P< .001). Tissue elongation was less extensive in group III compared to group I at 8 weeks (P< .001), while tissue cross-sectional area was decreased in both groups II and III compared to group I at 8 weeks (P< .001). All groups demonstrated decreases in tensile strength when compared to controls (P< .001). These findings suggest that postoperative immobilization is important following thermal shrinkage of connective tissue, as early activity can lead to stretching of the heat-modified tissue.
authors.affiliation: Steadman Hawkins Denver Clinic, Denver, Colorado 80111, USA.
authors.forename: Theodore F
authors.initials: TF
authors.lastname: Schlegel
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Faber
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Chen
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Hawkins
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000379:methods*; D055119:Elastic Modulus; D007103:Immobilization / Q000379:methods*; D017847:Patellar Ligament / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*; D011817:Rabbits; D013314:Stress, Mechanical; D016896:Treatment Outcome; D014945:Wound Healing