title: An anatomic study of the triquetrum-hamate joint.
abstract: OBJECTIVE
  To investigate the articulating surface of the triquetrum-hamate joint (TqH).
  
  
  METHODS
  The carpal bones of 46 wrist specimens were examined. The shape of the TqH joint surfaces were investigated, with focus on variations in the shape of the hamate and corresponding triquetrum and the presence and position of convex and concave surfaces.
  
  
  RESULTS
  Two distinct patterns of hamate TqH articular surfaces were identified, designated type I (31 of 46) and type II (15 of 46). The triquetral TqH articular surface also was found to have 2 distinct patterns, designated type A (18 of 46) and type B (15 of 46). Of the triquetrums examined 13 of 46 had characteristics that were a variable mixture of the 2 identifiable triquetral surface types, but these did not have sufficient similarity to constitute a third triquetrum surface type. The corresponding articulation patterns of these joint surfaces showed a strong trend for a type A triquetrum to articulate with a type I hamate (18 of 46 of all joints) and for a type B triquetrum to articulate with a type II hamate (13 of 46 of all joints). No association was seen between lunate types and type I or type II hamates.
  
  
  CONCLUSIONS
  These findings suggest the existence of 2 distinct TqH joint patterns, which have been termed TqH-1 and TqH-2. There appears to be a spectrum of variation between these 2 identifiable types. As a result, the TqH is best described as a spectrum, with TqH-1 at one end and TqH-2 at the other. A TqH-1 joint is a helicoidal configuration. It is double-faceted, with the hamate and the triquetrum articular surfaces possessing complementary concave and convex parts. A TqH-2 joint has a predominantly oval convex shape, whereas the primarily concave triquetrum is better described as a dish for the flatter hamate. It has no hamate groove or distal ridge.
authors.affiliation: Department of Orthopaedic Surgery, Royal Adelaide Hospital, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: James
authors.initials: J
authors.lastname: McLean
authors.forename: Gregory
authors.initials: G
authors.lastname: Bain
authors.forename: Michael
authors.initials: M
authors.lastname: Eames
authors.forename: Quintin
authors.initials: Q
authors.lastname: Fogg
authors.forename: Nicholas
authors.initials: N
authors.lastname: Pourgiezis
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D050824:Carpal Joints / Q000033:anatomy & histology*; D051225:Hamate Bone / Q000033:anatomy & histology*; D006801:Humans; D008875:Middle Aged; D051221:Triquetrum Bone / Q000033:anatomy & histology*