title: Opening wedge trapezial osteotomy as possible treatment for early trapeziometacarpal osteoarthritis: a biomechanical investigation of radial subluxation, contact area, and contact pressure.
abstract: OBJECTIVE
  Radial subluxation and cartilage thinning have been associated with initiation and accelerated development of osteoarthritis of the trapeziometacarpal joint. Few investigators have reported on the benefits of opening wedge trapezial osteotomy for altering the contact mechanics of the trapeziometacarpal joint as a possible deterrent to the initiation or progression of osteoarthritis. We used cadaveric specimens to determine whether opening wedge osteotomy of the trapezium was successful in reducing radial subluxation of the metacarpal base and to quantify the contact area and pressure on the trapezial surface during simulated lateral pinch.
  
  
  METHODS
  We used 8 fresh-frozen specimens in this study. The flexor pollicis longus, abductor pollicis longus, adductor pollicis, abductor pollicis brevis, and flexor pollicis brevis/opponens pollicis tendons were each loaded to simulate the thumb in lateral pinch position. We measured radial subluxation from anteroposterior radiographs before and after placement of a 15° wedge. We used real-time sensors to analyze contact pressure and contact area distribution on the trapezium.
  
  
  RESULTS
  Center of force in the normal joint under lateral pinch loading was primarily located in the dorsal region of the trapezium. After wedge placement, contact pressure increased in the ulnar-dorsal region by 76%. Mean contact area increased in the ulnar-dorsal region from 0.05 to 0.07 cm(2), and in the ulnar-volar region from 0.003 to 0.024 cm(2). The average reduction in joint subluxation was 64%.
  
  
  CONCLUSIONS
  The 15° opening wedge osteotomy of the trapezium reduced radial subluxation of the metacarpal on the trapezium and increased contact pressure and contact area away from the diseased compartments of the trapezial surface. Trapezial osteotomy addresses the 2 preeminent theories about the initiation and progression of osteoarthritis.
  
  
  CONCLUSIONS
  By reducing radial subluxation and altering contact pressure and contact area, trapezial osteotomy may prove an alternative to first metacarpal extension osteotomy or ligament reconstruction in early stages of degenerative arthritis of the trapeziometacarpal joint.
authors.affiliation: Department of Orthopaedics, University of New Mexico, Albuquerque, NM, USA.
authors.forename: Tahseen
authors.initials: T
authors.lastname: Cheema
authors.forename: Christina
authors.initials: C
authors.lastname: Salas
authors.forename: Nathan
authors.initials: N
authors.lastname: Morrell
authors.forename: Letitia
authors.initials: L
authors.lastname: Lansing
authors.forename: Mahmoud M
authors.initials: MM
authors.lastname: Reda Taha
authors.forename: Deana
authors.initials: D
authors.lastname: Mercer
mesh_terms: D001696:Biomechanical Phenomena; D020342:Finite Element Analysis; D006801:Humans; D010003:Osteoarthritis / Q000503:physiopathology / Q000601:surgery*; D010027:Osteotomy / Q000379:methods*; D011312:Pressure; D011884:Radius / Q000503:physiopathology; D051222:Trapezium Bone / Q000601:surgery*; D014955:Wrist Joint / Q000503:physiopathology / Q000601:surgery