title: Changes in Wrist Motion After Simulated Scapholunate Arthrodesis: A Cadaveric Study.
abstract: OBJECTIVE
  A high incidence of nonunion and relatively poor outcomes with prior fixation techniques has precluded scapholunate (SL) arthrodesis as a standard treatment for SL instability. Our purpose was to determine the impact on range of motion (ROM) of simulated SL arthrodesis via headless screw fixation.
  
  
  METHODS
  We performed baseline wrist ROM for 10 cadaveric wrists using a standardized mounting-and-weights system. Extension, flexion, radial deviation, ulnar deviation, dart-thrower's extension, and dart-thrower's flexion were assessed. Two 3.0-mm headless compression screws were inserted across the SL joint to simulate SL arthrodesis. Goniometric measurements and fluoroscopic imaging were repeated to assess ROM differences after simulated SL arthrodesis. We assessed SL angle and gap during testing to ensure there was no significant motion between the scaphoid and lunate, thus confirming stable simulated fusion. Differences in ROM were compared between baseline and simulated SL arthrodesis using paired t tests.
  
  
  RESULTS
  Mean SL angle remained constant between pre- and post-arthrodesis imaging (47° ± 6° vs 46° ± 4°) and did not change during post-arthrodesis ROM testing, indicating a stable simulated fusion. Compared with baseline, SL arthrodesis had a statistically significant reduction in maximum flexion of 6° and 9° based on fluoroscopy and goniometry, respectively, in dart-thrower's extension of 5° and 9° based on fluoroscopy and goniometry, respectively, and in dart-thrower's flexion of 6° for both fluoroscopy and goniometry. No other ROMs after simulated SL arthrodesis were significantly different compared with baseline.
  
  
  CONCLUSIONS
  The effects of simulated SL arthrodesis on radiocarpal and midcarpal motion compare favorably with motion after SL soft tissue repair and other reconstructive techniques that have been previously reported. The statistically significant decreases in wrist flexion and dart-thrower's extension-flexion after simulated SL arthrodesis are of questionable clinical importance.
  
  
  CONCLUSIONS
  These results may support reconsidering SL arthrodesis as a viable treatment option for acute or chronic SL instability with regard to apparent minimal adverse effects on functional wrist ROM.
authors: Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, MD.
authors: Kevin D
authors: KD
authors: Han
authors: Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, MD.
authors: Jaehon M
authors: JM
authors: Kim
authors: Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, MD.
authors: Michael V
authors: MV
authors: DeFazio
authors: Universidad Central de Venezuela, Caracas, Venezuela.
authors: Ricardo J
authors: RJ
authors: Bello
authors: Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, MD.
authors: Ryan D
authors: RD
authors: Katz
authors: Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, MD.
authors: Brent G
authors: BG
authors: Parks
authors: Curtis National Hand Center, MedStar Union Memorial Hospital, Baltimore, MD. Electronic address: anne.mattson@medstar.net.
authors: Kenneth R
authors: KR
authors: Means
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001174:Arthrodesis; D053587:Arthrometry, Articular; D001863:Bone Screws; D002102:Cadaver; D005471:Fluoroscopy; D006801:Humans; D012667:Lunate Bone / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D016059:Range of Motion, Articular; D021361:Scaphoid Bone / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D014955:Wrist Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*
keywords: Scapholunate arthrodesis; cadaveric study; scapholunate fusion; scapholunate instability; wrist arthritis