Measurement of the Flexing Force of the Fingers by a Dynamic Splint With a Dynamometer

Abstract

PURPOSE AND METHODS:In order to determine forces acting upon an articular joint during hand rehabilitation, a dynamic splint was built and connected to a dynamometer (capable of measuring forces in the range 0 -600 gf). Through trigonometric calculation, the authors measured the flexing force in the proximal interphalangeal joint of the middle finger at 30°, 45°, 60°, and 90° of flexion. Measurements were obtained in a population of 40 voluntary adults, 20 females and 20 males, This flexing force was correlated with age, sex, and anthropometric measures. RESULTS: Force in the flexing tendon is maximal at the start of flexion, and decreases as the angle of joint flexion increases. A relationship was observed between finger length and the magnitude of the force exerted on the tendon: the longer the finger, the greater the force exherted upon the tendon. Force is greater at all the measured angles, (except 30°) in males and in individuals of higher stature, and bigger arm span. CONCLUSIONS: The flexing force can be effectively measured at all flexing angles, that it correlates with a number of different anthropometric parameters, and that such data are likely to open the way for future studies.

Establishing a reproducible protocol for measuring index active extension strength

“…Our results demonstrate that our measurement protocol of independent and dependent index extension strength is reproducible. Similar to Silva et al (2005) and Richards et al (1993), we believe that our reproducibility is due to a rigid construct that fastened the dynamometer and to a protocol in which the subject’s position was maintained to avoid compensation by wrist extensors. Nevertheless, these studies were looking at measuring different motions: Richards et al (1993) measured extension strength of the metarcapo-phalangeal joints; and Silva et al (2005) measured flexion force at the middle phalanx.…”

“…Published reproducible muscle strength measurement protocols of the upper limb exist. Silva et al (2005) used a dynamometer secured to a static splint to measure extrinsic flexor tendon strength of the middle finger at the middle phalanx. The splint held the wrist and metarcapo-phalangeal joints straight to limit compensation by wrist flexor and intrinsic muscles.…”

“…Dependent extension involved active index finger extension as well as active extension of all the fingers. The tests were performed three times in a row in both settings on each hand by three examiners (Day 0 – D0) and repeated at Day 7 (D7) to determine the intra-examiner reproducibility and the inter-examiner reproducibility (Richards et al, 1993; Silva et al, 2005). When active extension of the wrist was observed by an elevation of the metacarpal heads from the stand, the test was repeated to obtain isolated extension of the fingers.…”

On Fabrication and Mechanical Testing of a New Finger Support

“…The researchers used trigonometric equations to calculate the flexing force at angles ranging from 25°-45°. From the study, it was observed that the larger the finger, the greater the force that is exerted on the tendon (Silva, et al, 2005). Hofmann and Goebl8 explored the finger force profiles and tongue techniques of clarinet students and professional clarinetists under controlled performance conditions.…”

System for measuring finger force profiles for dexterity assessment

“…There are different devices described in the literature designed for measuring finger flexion force [4][5][6], measuring both single finger and whole hand extension force [7], devices directly attached to the finger or as a glove [8][9][10]. Aside from studies concerning voluntary finger forces, involuntary "crosstalk" between fingers was investigated for measuring synergistic finger contractions [11].…”