The effect of cyclic forces upon finger joints with impaired ranges of motion

  • David Carus

    Student thesis: Doctoral Thesis


    The two aims of this research programme were;

    (1) To study the effects of the application of continuous passive motion (CPM) upon finger joints with limited range of motion (ROM).

    (2) To investigate the development of a prototype CPM machine for hand rehabilitation after flexor tendon repairs.

    The principal results of the research were;

    (1) Tests upon patients using purpose-built instrumented machines, performed in order to obtain data on the magnitudes and nature of the forces exerted during CPM therapy, revealed that the force magnitudes were surprisingly high. Tensile forces (pulling fingers into flexion) and compressive forces (pushing fingers into extension) of 15 and 10 Newtons respectively were recorded though typical maximum forces were 7 and 6 Newtons.

    (2) The trends observed in the force data were neither dramatic nor consistent. In part, this was caused by active finger movements, coupling effects between adjacent fingers and by some slight slippage of the machine’s attachment rod on the fingers.

    (3) Gains in the range of finger joint range of motion (ROM), were consistently obtained during CPM treatment, but were rarely retained in the non-CPM periods.

    (4) The practical problem of preventing the slippage of the CPM machine’s attachment rod on the fingers could be minimised by the application of a linkage, which was developed during the research programme. This linkage has the further benefit that it can be used to mobilise finger joints in a selective manner. The linkage was satisfactorily tested and is regarded as a significant contribution to orthotic design. Further research will be necessary to demonstrate the effectiveness of the linkage for patients who require hand rehabilitation after flexor tendon repairs.

    (5) A control group of patients with Dupuytren’s contractures was studied to find the time needed for the return of function when CPM is not applied. Using the assumption that hand strength is related to functional recovery (because of dispersal of oedema), it was found that recovery takes eight weeks. It was reasoned that, in the general case, CPM should be applied for eight weeks after surgery or injury.
    Date of AwardApr 1998
    Original languageEnglish
    SponsorsNorman Fraser Design Trust, British Council, Deutscher Akademischer Austauschdienst & Arthritis and Rheumatism Council

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