title: The safety of the posterior ankle arthroscopy in management of posterior ankle impingement: A cadaveric study.
abstract: BACKGROUND
  Arthroscopic management of the posterior ankle impingement with the patient in supine position has the advantage of dealing with anterior ankle pathology at the same time without the need to change position of the patient. This study aims at evaluation of the safety of portal establishment and instrumentation of this technique.
  
  
  METHODS
  Sixteen fresh-frozen cadaver specimens were used. The relationships of the posteromedial and posterolateral portals to the adjacent tendons and nerves and the relationship of the coaxial portal tract with the posterior ankle capsule and the flexor hallucis longus tendon were studied.
  
  
  RESULTS
  Angle θ1 between the intermalleolar line and the posterior ankle coaxial portal tract averaged 1° (-10° to 22°). Angle θ2 between the intermalleolar line and the metal rod where the neurovascular bundle started to move averaged 19° (10° to 30°). Angle θ3 between the intermalleolar line and the metal rod where it reached the lateral border of the Achilles tendon was larger than angle θ2 in all specimens. The angle of safety (θs) averaged 18° (-1° to 26°).
  
  
  CONCLUSIONS
  Injury to the tendon, nerves or vessels is possible during establishment of the portals and resection of the os trigonum.
authors.affiliation: Department of Orthopaedics and Traumatology, North District Hospital, 9 Po Kin Road, Sheung Shui, NT, Hong Kong SAR, China. Electronic address: luithderek@yahoo.co.uk.
authors.forename: T H
authors.initials: TH
authors.lastname: Lui
authors.affiliation: Institute of Medical and Health Sciences Education and Department of Anatomy, The University of Hong Kong, Li Ka Shing Faculty of Medicine, Hong Kong SAR, China. Electronic address: lapki@hkucc.hku.hk.
authors.forename: L K
authors.initials: LK
authors.lastname: Chan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016512:Ankle Injuries / Q000601:surgery*; D001182:Arthroscopy / Q000379:methods*; D002102:Cadaver; D006801:Humans; D007431:Intraoperative Complications / Q000517:prevention & control; D008875:Middle Aged; D009408:Nerve Compression Syndromes / Q000601:surgery*; D059348:Peripheral Nerve Injuries / Q000517:prevention & control; D053682:Tendon Entrapment / Q000601:surgery*; D013708:Tendon Injuries / Q000517:prevention & control
keywords: Ankle arthroscopy; Anterior ankle impingement; Endoscopy; Os trigonum; Posterior ankle impingement