Why and how do locking plates fail?

Gueorguiev, Boyko; Lenz, Mark

doi:10.1016/s0020-1383(18)30305-x

Cited by 35 publications

(39 citation statements)

References 40 publications

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“…Newly emerging implants such as angle-stable locking plates allow biological flexible fracture fixation based on the principle of an internal fixator [28]. Although they show excellent biomechanical performance [29], their clinical results are rather discouraging with catastrophic rates of nonunion (19%) and mechanical failure (38%) [30].…”

Section: Treatment Of Trochanteric Fracturesmentioning

confidence: 99%

Biomechanics of Osteoporotic Fracture Fixation

Hollensteiner

Sandriesser

Bliven

et al. 2019

Curr Osteoporos Rep

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Purpose of Review Fractures of osteoporotic bone in elderly individuals need special attention. This manuscript reviews the current strategies to provide sufficient fracture fixation stability with a particular focus on fractures that frequently occur in elderly individuals with osteoporosis and require full load-bearing capacity, i.e., pelvis, hip, ankle, and peri-implant fractures. Recent Findings Elderly individuals benefit immensely from immediate mobilization after fracture and thus require stable fracture fixation that allows immediate post-operative weight-bearing. However, osteoporotic bone has decreased holding capacity for metallic implants and is thus associated with a considerable fracture fixation failure rate both short term and long term. Modern implant technologies with dedicated modifications provide sufficient mechanical stability to allow immediate weight-bearing for elderly individuals. Depending on fracture location and fracture severity, various options are available to reinforce or augment standard fracture fixation systems. Summary Correct application of the basic principles of fracture fixation and the use of modern implant technologies enables mechanically stable fracture fixation that allows early weight-bearing and results in timely fracture healing even in patients with osteoporosis.

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Section: Treatment Of Trochanteric Fracturesmentioning

confidence: 99%

Biomechanics of Osteoporotic Fracture Fixation

Hollensteiner

Sandriesser

Bliven

et al. 2019

Curr Osteoporos Rep

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“…According to the currently existing fixation techniques, locking screws are not used to exert compression. Insertion of a locking screw crossing the fracture line should therefore be avoided, since it acts as a set screw . As a result, such a screw stabilizes the fracture, however, keeps a gap between the fragments and blocks micromotions at the fracture site .…”

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confidence: 99%

LagLoc—a new surgical technique for locking plate systems

Triana

Gueorguiev

Sommer

et al. 2018

Journal Orthopaedic Research

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Treatment of oblique and spiral fractures remains challenging. The aim of this study was to introduce and investigate the new LagLoc technique for locked plating with generation of interfragmentary compression, combining the advantages of lag screw and locking-head-screw techniques. Oblique fracture was simulated in artificial diaphyseal bones, assigned to three groups for plating with a seven-hole locking compression plate. Group I was plated with three locking screws in holes one, four, and seven. The central screw crossed the fracture line. In group II the central hole was occupied with a lag screw perpendicular to fracture line, whereas holes one and seven were occupied with locking screws. Group III was instrumented applying the LagLoc technique as follows. Hole four was predrilled perpendicularly to the plate, followed by overdrilling of the near cortex and insertion of a locking screw-crossing the fracture line-whose head was covered by a holding sleeve to prevent temporarily the locking in the plate hole and generate interfragmentary compression. Subsequently, the screw head was released and locked in the plate hole. Holes one and seven were occupied with locking screws. Interfragmentary compression in the fracture gap was measured using pressure sensors. All screws in the three groups were tightened with 4 Nm torque. Interfragmentary compression in group I (167 ± 25 N) was significantly lower in comparison to groups II (431 ± 21 N) and III (379 ± 59 N), p ≤ 0.005. The difference in compression between groups II and III remained not significant (p = 0.999). The new LagLoc technique offers an alternative tool to generate interfragmentary compression with the application of locking plates by combining the biomechanical advantages of lag screw and locking screw fixations. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

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“…The initial stability and screw fixation are essential because if they are compromised, the onset of head collapse commences. Implant loosening as a result of weak anchorage in poor bone quality is a still commonly reported complication with adverse effects on the recovery of a patient . In our study, the screw loosening event could be identified by the initial loss of stability before the onset of perforation accompanied by the head varus collapse.…”

Section: Discussionmentioning

confidence: 73%

Secondary Perforation Risk in Plate Osteosynthesis of Unstable Proximal Humerus Fractures: A Biomechanical Investigation of the Effect of Screw Length

Ciric

Mischler

Qawasmi

et al. 2019

Journal Orthopaedic Research

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Secondary perforation of screws into the joint surface is a commonly reported mechanical fixation failure mode in locked plating of proximal humerus fractures (PHF). This study investigated the influence that screws tip to joint distance (TJD) has on the biomechanical risk of secondary screw perforation and the stability of PHF. Ten pairs of cadaveric proximal humeri with a wide range of bone mineral density were used. Each specimen was osteotomized and instrumented with the PHILOS plate, simulating a highly unstable 3-part fracture. Bones were randomized into a long screw group (LSG) with 4 mm TJD, or a short screw group (SSG) with 8 mm TJD. A custom biomechanical setup was used to test the samples to failure cyclically with a constant valley load and an increasing ramp. The number of cycles to the initial screw loosening event was significantly higher for the LSG (mean ± standard deviation: 17,532 ± 6,458) compared with the SSG (11,102 ± 5,440) (p < 0.01). The mode of failure during testing was lateral-inferior displacement combined with varus collapse, with calcar screws perforating first. The number of cycles to failure event for LSG (27,849 ± 5,648) was not significantly different compared with SSG (28,782 ± 7,307) (p = 0.50). Screws that purchase closer to the joint had better initial stability and resistance against loosening. Placing longer screws, within limits dictated by the surgical guide, is expected to decrease the risk of secondary perforation failures in unstable PHF. These findings require clinical corroboration.

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Why and how do locking plates fail?

Cited by 35 publications

References 40 publications

Biomechanics of Osteoporotic Fracture Fixation

Biomechanics of Osteoporotic Fracture Fixation

LagLoc—a new surgical technique for locking plate systems

Secondary Perforation Risk in Plate Osteosynthesis of Unstable Proximal Humerus Fractures: A Biomechanical Investigation of the Effect of Screw Length

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