title: Histologic evaluation of the shoulder capsule in normal shoulders, unstable shoulders, and after failed thermal capsulorrhaphy.
abstract: BACKGROUND
  Attenuation of the shoulder capsule has been noted during revision surgery for failed thermal capsulorrhaphy.
  
  
  OBJECTIVE
  The attenuated capsule seen in patients who have undergone failed thermal capsulorrhaphy will show histologic characteristics distinguishing it from the capsule of normal shoulders and dislocating shoulders.
  
  
  METHODS
  Case control study.
  
  
  METHODS
  The shoulder capsules were studied in 12 patients with traumatic anterior instability and in 7 patients who experienced recurrent instability after a thermal capsulorrhaphy. The capsules of six fresh-frozen cadavers with no shoulder lesions were used as controls.
  
  
  RESULTS
  Among patients who had a history of traumatic instability, a denuded synovial layer was present in 58%, subsynovial edema in 58%, increased cellularity in 25%, and increased vascularity in 83%. At the time of surgery, five of seven shoulders in the failed thermal capsulorrhaphy group (71%) were subjectively felt to be thin and attenuated. Denuded synovium was found in 100% of these patients, subsynovial edema in 43%, and changes in the collagen layer in 100%. Changes in the collagen layer in these patients included a "hyalinization" appearance in five cases (71%), increased collagen fibrosis in two cases (29%), and increased cellularity in two cases (29%).
  
  
  CONCLUSIONS
  There was no one characteristic observable on histologic evaluation that would explain the attenuation of the capsule in cases of failed thermal treatment. Morphologic collagen structure can be histologically abnormal for up to 16 months after thermal capsulorrhaphy.
authors.affiliation: Division of Sports Medicine and Shoulder Surgery, Department of Orthopaedic Surgery, The Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Edward G
authors.initials: EG
authors.lastname: McFarland
authors.forename: Tae Kyun
authors.initials: TK
authors.lastname: Kim
authors.forename: Prachan
authors.initials: P
authors.lastname: Banchasuek
authors.forename: Edward F
authors.initials: EF
authors.lastname: McCarthy
mesh_terms: D000293:Adolescent; D000328:Adult; D001182:Arthroscopy; D002102:Cadaver; D016022:Case-Control Studies; D006358:Hot Temperature; D006801:Humans; D017746:Joint Capsule / Q000473:pathology* / Q000601:surgery; D007593:Joint Instability / Q000473:pathology*; D008875:Middle Aged; D012044:Regression Analysis; D012783:Shoulder Dislocation / Q000473:pathology*; D012785:Shoulder Joint / Q000473:pathology*