title: [Use of a water jet for synovectomy: in vitro study of feasibility].
abstract: OBJECTIVE
  The selectivity of a water jet (WJ) is already used with clinical advantage in the surgery of liver, brain, kidney and herniated lumbar discs. The aim of the present study was to determine whether a WJ can be used for synovectomy without damaging the joint capsule and the cartilage.
  
  
  METHODS
  60 human cadaver knee specimens (67 +/- 14 years) were dissected into synovial and cartilage samples. They were randomly assessed to four pressure groups (pW = 3; 6; 9; 12 MPa) and three jet surface angles (beta = 30; 60; 90 degrees) The nozzle diameter was dD = 0.12 mm, the stand off distance of the jet was s = 10 mm with a feed rate of vV = 2 mm/s. The acquired parameters were depth of the cuts, histological layer, and change of the samples thickness.
  
  
  RESULTS
  There was a correlation of the cutting depth and the pressure (pW), whereas the jet-surface angle (beta) showed no correlation. The synovial layer of the cut likewise correlated with the pressure. At pW = 6 MPa the stratum subsynoviale could be cut selectively without damaging the fibrous capsule or the cartilage. The increase of the samples thickness was caused by an interstitial oedema.
  
  
  CONCLUSIONS
  The different mechanical properties of the joint capsule and the stratum subsynoviale lead to the selective cutting of the water jet. Since the joint capsule was not damaged, the feasibility of WJ synovectomy has been proven. The device can be used for synovectomy in parts of the joint that are not visible as well as in very small joints.
authors.affiliation: Orthopädische Klinik, AK Eilbek, Hamburg. honl@ortho-hamburg.de
authors.forename: M
authors.initials: M
authors.lastname: Honl
authors.forename: H
authors.initials: H
authors.lastname: Uebeyli
authors.forename: O
authors.initials: O
authors.lastname: Dierk
authors.forename: K
authors.initials: K
authors.lastname: Schwieger
authors.forename: R
authors.initials: R
authors.lastname: Rentzsch
authors.forename: V
authors.initials: V
authors.lastname: Carrero
authors.forename: S
authors.initials: S
authors.lastname: Dries
authors.forename: A
authors.initials: A
authors.lastname: Betthäuser
authors.forename: W W
authors.initials: WW
authors.lastname: Höpker
authors.forename: E
authors.initials: E
authors.lastname: Hille
authors.forename: M
authors.initials: M
authors.lastname: Morlock
mesh_terms: D000368:Aged; D002358:Cartilage, Articular / Q000473:pathology; D004867:Equipment Design; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D006874:Hydrostatic Pressure; D066298:In Vitro Techniques; D017746:Joint Capsule / Q000473:pathology; D007719:Knee Joint / Q000473:pathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures / Q000295:instrumentation*; D000074402:Synovectomy; D013583:Synovial Membrane / Q000473:pathology