title: Histological and magnetic resonance imaging alterations after irradiation of meniscus using Holmium:YAG laser.
abstract: OBJECTIVE
  The authors performed an experimental and a prospective clinical study to evaluate the histological and magnetic resonance imaging (MRI) alterations after irradiation of meniscus using holmium:YAG (Ho:YAG) laser VersaPulse Select 60 watts and InfraTome Delivery Systems 30 degrees Handpiece (spot size at fiber tip 0.4 mm; Coherent Medical, Palo Alto, CA).
  
  
  BACKGROUND
  Recently, some authors reported a few cases with articular cartilage damage or paraarticular osteonecrosis following arthroscopic knee surgery in which the laser was used to assist in the treatment of meniscal pathology.
  
  
  METHODS
  Meniscus specimens in saline immersion were exposed to Ho:YAG laser irradiation. The laser wavelength was 2.1 microm and pulse duration was 250 microsec. Power settings were 1-1.5 joules per pulse and 10-15 Hz. Total laser energy used in these procedures was 2, 3.5, and 6 K joules. Eight patients with meniscal problems underwent arthroscopic partial meniscectomy using Ho:YAG laser. Total laser energy used for these surgeries was 1.5-2.5 K joules. MRI was performed preoperatively and at 6 months postoperatively.
  
  
  RESULTS
  At higher energy levels (more than 3 K joules), separation of the gap between the collagen fibers, and a three-dimensional dispersion in the striation were observed on electron microscopic evaluation of meniscus specimens. No patient had abnormal signals in MRI (a sign of articular cartilage damage or osteonecrosis) following arthroscopic laser surgery.
  
  
  CONCLUSIONS
  When higher energy level is required, conventional instruments should be preferred in the treatment of meniscal lesions. Laser should be reserved for the posteriorly located and smaller meniscal lesions.
authors.affiliation: Department of Orthopaedic Surgery, Gazi University Medical Faculty, Ankara, Turkey. atik@tr.net
authors.forename: O S
authors.initials: OS
authors.lastname: Atik
authors.forename: D
authors.initials: D
authors.lastname: Erdogan
authors.forename: S
authors.initials: S
authors.lastname: Omeroglu
authors.forename: T
authors.initials: T
authors.lastname: Tali
authors.forename: F
authors.initials: F
authors.lastname: Korkusuz
authors.forename: M M
authors.initials: MM
authors.lastname: Uslu
authors.forename: F
authors.initials: F
authors.lastname: Eksioglu
mesh_terms: D006695:Holmium; D006801:Humans; D007834:Lasers; D008279:Magnetic Resonance Imaging; D008592:Menisci, Tibial / Q000473:pathology / Q000528:radiation effects*
chemical_list: D006695:Holmium