The Load-Bearing Characteristics of the Forearm: Pattern of Axial and Bending Force Transmitted Through Ulna and Radius

Shaaban, Hassan; Giakas, Giannis; Bolton, M.; Williams, Robert Lee; Wicks, Paul; Scheker, Luis R.; Lees, Vivien C.

doi:10.1016/j.jhsb.2005.12.009

Cited by 55 publications

(36 citation statements)

References 14 publications

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“…20,21 Others have estimated that 60-90% of the load applied to the palm of the hand is transmitted through the radius, depending on the position of the arm and hand. [22][23][24] The cadaver donors tested here were considerably older and had lower bone massand thus probably higher surface strains-than the experimental subjects, Despite this limitation, the locations and patterns of peak strain are likely similar between specimens and subjects.…”

Section: Prospective Bone Adaptation In Womenmentioning

confidence: 99%

In vivo loading model to examine bone adaptation in humans: A pilot study

Troy

Edwards

Bhatia

et al. 2013

Journal Orthopaedic Research

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Bone is typically well suited for its habitual loading environment because of its ability to adapt. Although characteristics of the mechanical loading environment predict the bone adaptive response in animals, this has not been prospectively validated in humans. Here, we describe an in vivo loading model in which women apply forces to the radius by leaning onto their hand. We characterized the strain environment imposed on the radius using cadaveric experimentation and conducted a prospective study in which 19 adult women loaded their distal radii 50 cycles/day, 3 days/week, for 28 weeks and seven additional adult women served as controls. In four cadaveric specimens, loading caused compressive principal strains of À1,695 AE 396 me with radial bending dorsally and towards the ulna. Prospective in vivo loading produced measurable improvements to bone and appeared to protect against bone loss associated with seasonal fluctuations in physical activity and sun exposure. Experimental subjects had significant gains to bone volume (BV) and moments of inertia, while, control subjects had significant losses in BMC and moments of inertia. The loading model is thus suitable as a model system for exploring bone adaptation in humans, and may eventually be clinically useful for strengthening the radius of women. Keywords: upper extremity; wrist; quantitative computed tomography; CT; QCT Bone adapts its form and function to the mechanical loads it encounters during habitual activity. This adaptive process, accomplished via bone modeling and remodeling, is driven by mechanical stimuli (e.g., stress, strain, strain energy density, etc). The magnitude of the (re)modeling response depends on the degree to which the mechanical environment deviates from a particular set point. Here, the mechanical environment within the bone is a consequence of the collective applied external stimuli.1,2 In the physiologically normal bone, apposition will occur when the mechanical stimulus exceeds some maximum threshold, while resorption will occur when the mechanical stimulus falls below some minimum threshold. Most of the time, however, the mechanical stimulus falls within a range that initiates neither net apposition nor resorption, and the bone metabolic process is in homeostasis.Several studies have defined mechanical stimulus thresholds required to initiate an adaptive response within non-human bone. For example, it has been shown in the turkey ulna, that four wing flaps per day, which each provide a peak periosteal strain of approximately 2,000 micro-strain (me), is sufficient to maintain bone mass, as are 100 cycles of 1,000 me per day.3,4 Similarly, 10 jumps per day, 3 days per week is sufficient to elicit an osteogenic response in the tibiae of rats.5 Collectively, this animal work has established the importance of specific parameters for bone adaptation such as loading magnitude, 6 loading cycles, 7 loading frequency, 8 loading rate, 9 and timing between loads, 10,11 and between loading bouts. 12Because of challenges associated ...

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Section: Prospective Bone Adaptation In Womenmentioning

confidence: 99%

In vivo loading model to examine bone adaptation in humans: A pilot study

Troy

Edwards

Bhatia

et al. 2013

Journal Orthopaedic Research

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show abstract

“…1,2 The radius rotates about the fixed ulna via the DRUJ. 3 The stabilizing constraints of the DRUJ include its bony geometry and surrounding soft tissue support.…”

mentioning

confidence: 99%

Functional and Radiographic Outcomes Following Distal Ulna Implant Arthroplasty

Kakar

Swann

Perry

et al. 2012

The Journal of Hand Surgery

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“…The first series of these was undertaken on 12 cadaver limbs mounted on a custom-made jig. [19][20][21] Axial loads were applied via a balanced pulley system mounted to the rear of the jig. Force was measured in the DRUJ using Tekscan (Boston, MA, US) wrist sensors and, from these measurements, pressure profiles and contact areas and centroid positions were derived.…”

Section: Leesmentioning

confidence: 99%

Functional anatomy of the distal radioulnar joint in health and disease

Lees

2013

annals

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The distal radioulnar joint (DRUJ) is critical to the function of the forearm as a mechanical unit. This paper is concerned with the concepts and observations that have changed understanding of the function of the DRUJ, notably with respect to the biomechanics of this joint. The DRUJ has been shown to be important in acting to distribute load and removal of the ulna head leads to the biomechanical equivalent of a one-bone forearm. The soft tissues with topographical relations to the distal forearm and DRUJ have also been investigated in our experimental series with findings including the description of a clinical disorder termed subluxation-related ulna neuropathy syndrome.A working knowledge of the applied anatomy and biomechanics of the forearm and wrist is useful for any practitioner treating traumatic, developmental and degenerative disorders of the distal radioulnar joint (DRUJ), hand and forearm. The elbow, forearm and wrist act as a unified structure to provide a stable, strong and highly mobile strut for positioning the hand in space and for conducting load-bearing tasks. This paper is concerned with illuminating current concepts regarding the DRUJ and defining its place in the function of the forearm as a mechanical unit. What follows is a personal view and details some of our own experiments that have built on the contributions of other authors working in this field. Comparative anatomy of the DRUJThe DRUJ facilitates forearm rotation. During evolution the development of the DRUJ was probably as important as development of the opposable thumb in allowing human beings to manipulate their environment, facilitating development as hunter-gatherers. The human DRUJ is recognisable in that of the great apes whereas 'lower' mammals have a syndesmosis for a DRUJ. Mobility of the forearm allows apes to place the hand in three-dimensional (3D) space and enables them to swing through the tree branches, an action known as brachiation. Mobility of the hand and forearm in hominids that developed an upright stance was instability owing to ligament injury sustained as a result of falls on the outstretched hand. Applied anatomy of the DRUJ, TFC complex and osseoligamentous structures of the forearmThe DRUJ is one of a pair of hemijoints (uniaxial pivot joints) that function simultaneously permitting the movement of the forearm through the range of pronosupination, the other being the proximal radioulnar joint (PRUJ). The articulations occur between the head of the ulna on the sigmoid notch of the radius (DRUJ) and the head of the radius on the radial notch of the ulna (PRUJ). The key concept in understanding the pathophysiology of the DRUJ is to appreciate that one of its components, namely the ulna head, is essentially a fixed structure about which the specially adapted radius bone rotates.The ulna is essentially a straight bone with a dense, strong condensation of stabilising ligaments known as the triangular fibrocartilage (TFC) complex attaching the distal ulna to the hand and the ulna to the radius. The TFC...

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The Load-Bearing Characteristics of the Forearm: Pattern of Axial and Bending Force Transmitted Through Ulna and Radius

Cited by 55 publications

References 14 publications

In vivo loading model to examine bone adaptation in humans: A pilot study

In vivo loading model to examine bone adaptation in humans: A pilot study

Functional and Radiographic Outcomes Following Distal Ulna Implant Arthroplasty

Functional anatomy of the distal radioulnar joint in health and disease

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