title: Cellularity and apoptosis after radiofrequency-induced shrinkage of collagenous tissue: assessment of postoperative immobilization using an in vivo rabbit model.
abstract: BACKGROUND
  Electrothermally-assisted capsular shrinkage has been gaining increased acceptance in the treatment of shoulder instability. Its indication in ACL-deficient knees has been discussed recently.
  
  
  METHODS
  We examined the influence of immobilization on cell homeostasis of healing collagenous tissue after radiofrequency energy was applied to the patellar tendon in 23 rabbits. The animals were killed immediately after surgery (n = 6) or 3 weeks after surgery (n = 17). 10 rabbits were allowed normal cage activity, whereas the treated hind limb of 7 animals was immobilized for 3 weeks in a cast. Feulgen staining was used to stain the DNA of cell nuclei. Cells undergoing apoptosis were identified by the TUNEL method. Quantitative histological assessment was performed using imaging analysis software.
  
  
  RESULTS
  Severe cellular damage in RF-treated collagenous tissue was partly induced by the immediate onset of apoptosis. At 3 weeks after surgery, non-immobilized tendon showed increased cellularity and apoptosis, whereas immobilization prevented the increase in cellularity and apoptosis significantly. The calculated ratio of apoptosis was not influenced by any postoperative treatment.
  
  
  CONCLUSIONS
  Diminished cellularity and apoptosis during tissue remodeling, due to immobilization, may protect the shortened collagenous scaffold from stretching and further optimize the clinical outcome after radiofrequency shrinkage. To stabilize the shrunken tissue, proliferation during postoperative wound healing should be minimized by careful rehabilitation.
authors.affiliation: Department of Orthopaedics, University Hospital Münster, Germany. pkuempers@htp-tel.de
authors.forename: Philipp
authors.initials: P
authors.lastname: Kümpers
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Pötzl
authors.forename: Till
authors.initials: T
authors.lastname: Heusner
authors.forename: Jörn
authors.initials: J
authors.lastname: Steinbeck
authors.forename: Thomas
authors.initials: T
authors.lastname: Szuwart
mesh_terms: D000818:Animals; D017209:Apoptosis; D017115:Catheter Ablation / Q000009:adverse effects*; D002452:Cell Count; D003094:Collagen; D005260:Female; D007103:Immobilization; D010329:Patella / Q000166:cytology* / Q000473:pathology / Q000601:surgery; D011182:Postoperative Care; D011817:Rabbits; D013710:Tendons / Q000166:cytology* / Q000473:pathology / Q000601:surgery; D014945:Wound Healing
chemical_list: D003094:Collagen