title: Biomechanical characteristics of hemi-hamate reconstruction versus volar plate arthroplasty in the treatment of dorsal fracture dislocations of the proximal interphalangeal joint.
abstract: OBJECTIVE
  To compare stability and range of motion after hemi-hamate reconstruction versus volar plate arthroplasty in a biomechanical proximal interphalangeal (PIP) joint fracture-dislocation model.
  
  
  METHODS
  Eighteen digits from 6 cadaver hands were tested. We created defects of 40%, 60%, and 80% in the palmar base of each digit's middle phalanx, simulating an acute PIP joint fracture-dislocation. Each defect scenario was reconstructed with a hemi-hamate arthroplasty followed by a volar plate arthroplasty. A computer-controlled mechanism was used to bring each digit's PIP joint from full extension to full flexion via the digital tendons in each testing state, and in the intact state. During each testing scenario we collected PIP joint cinedata in a true lateral projection using mini-fluoroscopy. A digital radiography program was used to measure the amount of middle phalanx dorsal translation (subluxation) in full PIP joint extension. We recorded the angle at which subluxation, if present, occurred during each testing scenario.
  
  
  RESULTS
  Average dorsal displacement of the middle phalanx in relation to the proximal phalanx was 0.01 mm for the hemi-hamate reconstructed joints and -0.03 mm for the volar plate arthroplasty, compared with the intact state. Flexion contractures were noted in each of the specimens reconstructed with volar plate arthroplasty. Degree of contracture was directly correlated with defect size, averaging 20° for 40% defects, 35° for 60% defects, and 60° for 80% defects. We observed no flexion contractures in the hemi-hamate reconstructions.
  
  
  CONCLUSIONS
  Surgeons can use both hemi-hamate and volar plate arthroplasty to restore PIP joint stability following a fracture dislocation with a large middle phalanx palmar base defect. Use of volar plate arthroplasty led to an increasing flexion contracture as the middle phalanx palmar base defect increased.
  
  
  CONCLUSIONS
  Clinicians can use the information from this study to help with surgical decision-making and patient education.
authors.affiliation: The Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, MD.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Tyser
authors.affiliation: The Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, MD.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Tsai
authors.affiliation: The Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, MD.
authors.forename: Brent G
authors.initials: BG
authors.lastname: Parks
authors.affiliation: The Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, MD. Electronic address: anne.mattson@medstar.net.
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Means
mesh_terms: D001178:Arthroplasty / Q000379:methods*; D001696:Biomechanical Phenomena / Q000502:physiology*; D001863:Bone Screws; D005384:Finger Joint / Q000503:physiopathology* / Q000601:surgery*; D051225:Hamate Bone / Q000637:transplantation*; D006801:Humans; D066298:In Vitro Techniques; D057072:Intra-Articular Fractures / Q000503:physiopathology* / Q000601:surgery*; D004204:Joint Dislocations / Q000503:physiopathology* / Q000601:surgery*; D008954:Models, Biological; D053401:Palmar Plate / Q000601:surgery*; D011183:Postoperative Complications / Q000503:physiopathology*; D016059:Range of Motion, Articular / Q000502:physiology*
keywords: Proximal interphalangeal joint fracture dislocation; hemi-hamate arthroplasty; volar plate arthroplasty