The design and testing of external fixator bone screws

Evans, M.; Cunningham, J L; Harris, J D

doi:10.1016/0021-9290(90)90095-k

Cited by 6 publications

(15 citation statements)

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“…Aseptic loosening of screws is a significant clinical problem that is generally attributed to over or under exposure to strain (Huiskes et al 1985;Evans et al 1990;Turner et al 1997;Stoffel et al 2003). Moreover, this threshold may be below the yield strain of bone (Sugiura et al 2000) and osteoporotic bone is thought to be more susceptible to loosening than healthy bone (Gardner et al 2004).…”

Section: Introductionmentioning

confidence: 97%

Reasons why dynamic compression plates are inferior to locking plates in osteoporotic bone: a finite element explanation

MacLeod

Simpson

Pankaj

2014

Computer Methods in Biomechanics and Biomedical Engineering

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While locking plate fixation is becoming increasingly popular for complex and osteoporotic fractures, for many indications compression plating remains the standard choice. This study compares the mechanical behaviour of the more recent locking compression plate (LCP) device, with the traditional dynamic compression plates (DCPs) in bone of varying quality using finite element modelling. The bone properties considered include orthotropy, inhomogeneity, cortical thinning and periosteal apposition associated with osteoporosis. The effect of preloads induced by compression plating was included in the models. Two different fracture scenarios were modelled: one with complete reduction and one with a fracture gap. The results show that the preload arising in DCPs results in large principal strains in the bone all around the perimeter of the screw hole, whereas for LCPs large principal strains occur primarily on the side of the screw proximal to the load. The strains within the bone produced by the two screw types are similar in healthy bone with a reduced fracture gap; however, the DCP produces much larger strains in osteoporotic bone. In the presence of a fracture gap, the DCP results in a considerably larger region with high tensile strains and a slightly smaller region with high compressive strains. These findings provide a biomechanical basis for the reported improved performance of locking plates in poorer bone quality.

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Section: Introductionmentioning

confidence: 97%

Reasons why dynamic compression plates are inferior to locking plates in osteoporotic bone: a finite element explanation

MacLeod

Simpson

Pankaj

2014

Computer Methods in Biomechanics and Biomedical Engineering

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“…Other factors which have been found experimentally to increase the holding power of cancellous bone screws include: increasing the major diameter of the screw, 24 increasing the length of engaged screw thread, 12 inserting the screw in cancellous bone of greater apparent density and shear strength 6 and decreasing the thread pitch. 13 The holding power of a screw in bone is a function of both the design of the screw and the properties of the bone into which it is inserted. 1,32 Surgical screws are designed to generate a compressive force when a torsional moment is applied to the screw head.…”

Section: Cancellous Screwsmentioning

confidence: 99%

A modified operative technique for enhanced compression of medial malleolar non-union

Madhu

Morgan–Jones

2005

Injury Extra

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“…Artificial bone models created from photoelastic plastics have been used to evaluate the PBI (5,16,19,20). Photoelastic models are composed of synthetic resins which fluoresce under polarized light when a load is applied.…”

Section: Histological Evaluationmentioning

confidence: 99%

Enhancing External Skeletal Fixation Pin Performance: Consideration of the Pin-Bone Interface

Clary¹,

Roe²

1995

Vet Comp Orthop Traumatol

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SummaryThe integrity of an external skeletal fixator relies heavily on the pin-bone interface (PBI). Investigation of this interface have focused on histological, mechanical, thermal and clinical assessments. In this review the factors which are important for optimizing the strength and longevity of the PBI are presented. Pin design, pin insertion technique, bone quality and tissue response are considered.External skeletal fixation is used increasingly in human and veterinary orthopaedics. Pin loosening and infection are the primary causes of device failure and patient morbidity. Using several different techniques, researchers have identified a number of factors which affect the integrity of the pin-bone interface. These include pin design, pin insertion technique, initial bone quality and the osseous response to pin implantation and loading.

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The design and testing of external fixator bone screws

Cited by 6 publications

References 0 publications

Reasons why dynamic compression plates are inferior to locking plates in osteoporotic bone: a finite element explanation

Reasons why dynamic compression plates are inferior to locking plates in osteoporotic bone: a finite element explanation

A modified operative technique for enhanced compression of medial malleolar non-union

Enhancing External Skeletal Fixation Pin Performance: Consideration of the Pin-Bone Interface

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