title: Assessing Finger Joint Biomechanics by Applying Equal Force to Flexor Tendons In Vitro Using a Novel Simultaneous Approach.
abstract: BACKGROUND
  The flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) are critical for finger flexion. Although research has recently focused on these tendons' coactivity, their contributions in different tasks remain unclear. This study created a novel simultaneous approach to investigate the coactivity between the tendons and to clarify their contributions in different tasks.
  
  
  METHODS
  Ten human cadaveric hands were mounted on our custom frame with the FDS and FDP of the third finger looped through a mechanical pulley connected to a force transducer. Joint range of motion, tendon excursion and loading force were recorded during individual joint motion and free joint movement from rest to maximal flexion. Each flexor tendon's moment arm was then calculated.
  
  
  RESULTS
  In individual motions, we found that the FDP contributed more than the FDS in proximal interphalangeal (PIP) joint motion, with an overall slope of 1.34 and all FDP-to-FDS excursion (P/S) ratios greater than 1.0 with force increase. However, the FDP contributed less than the FDS in metacarpophalangeal (MCP) joint motion, with an overall slope of 0.95 and P/S ratios smaller than 1.0 throughout the whole motion except between 1.9% and 13.1% force. In free joint movement, the FDP played a greater role than the FDS, with an overall ratio of 1.37 and all P/S ratios greater than 1.0.
  
  
  CONCLUSIONS
  The new findings include differences in finger performance and excursion amounts between the FDS and FDP throughout flexion. Such findings may provide the basis for new hand models and treatments.
authors: Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.|Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan.|Biomechanics & Tendon and Soft Tissue Biology Laboratory, Division of Orthopedic Research, Mayo Clinic, Rochester, Minnesota, United States of America.
authors: Tai-Hua
authors: TH
authors: Yang
authors: Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.|Biomechanics & Tendon and Soft Tissue Biology Laboratory, Division of Orthopedic Research, Mayo Clinic, Rochester, Minnesota, United States of America.
authors: Szu-Ching
authors: SC
authors: Lu
authors: Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.|Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan.
authors: Wei-Jr
authors: WJ
authors: Lin
authors: Rehabilitation Medicine Research Center, Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, Minnesota, United States of America.
authors: Kristin
authors: K
authors: Zhao
authors: Biomechanics & Tendon and Soft Tissue Biology Laboratory, Division of Orthopedic Research, Mayo Clinic, Rochester, Minnesota, United States of America.
authors: Chunfeng
authors: C
authors: Zhao
authors: Biomechanics & Tendon and Soft Tissue Biology Laboratory, Division of Orthopedic Research, Mayo Clinic, Rochester, Minnesota, United States of America.
authors: Kai-Nan
authors: KN
authors: An
authors: Department of Orthopedic, National Cheng Kung University, Tainan, Taiwan.
authors: I-Ming
authors: IM
authors: Jou
authors: Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.|Department of Orthopedics, Show Chwan Memorial Hospital, Changhua, Taiwan.
authors: Pei-Yuan
authors: PY
authors: Lee
authors: Department of Occupational Therapy, National Cheng Kung University, Tainan, Taiwan.
authors: Li-Chieh
authors: LC
authors: Kuo
authors: Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.|Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan.
authors: Fong-Chin
authors: FC
authors: Su
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D005384:Finger Joint / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D008297:Male; D008662:Metacarpophalangeal Joint / Q000033:anatomy & histology / Q000502:physiology*; D008875:Middle Aged; D016059:Range of Motion, Articular; D013710:Tendons / Q000033:anatomy & histology / Q000502:physiology*