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This paper follows up on a recent systematic review of test methods and parameters for biomechanical testing of bone plates and it is the first study that contains recommendations for standardized mechanical testing of bone plate-screw constructs for osteosynthesis. Following the testing philosophy of ASTM F382 and ISO 9585, we have developed standardized quasi-static and dynamic testing methods for straight linear and anatomically shaped plates, including locked type and conventional systems. The test specification comprises torsion and bending tests along the implant axis and therefore modifies and extends the methods proposed by ASTM F382. We present specific test setups in order to determine product-specific characteristics of the mechanical construct, consisting of the bone plate with corresponding screws (such as construct stiffness, yield strength, ultimate strength and fatigue properties) under the condition that it is rigidly fixed to "healthy bone". We also address specific testing requirements that are important for the purpose of standardization, such as the positioning of the construct for testing or the number of screws in the diaphysis and metaphysis. Finally, we define the outcome parameters and associated failure criteria related to quasi-static and dynamic testing for comparative purposes. This paper does not intend to replace biomechanical testing of those devices under physiological loading conditions.

In the published literature there are controversial data to the biomechanical stability of monocortical comparing to the bicortical fixation of metacarpal fractures. The aim of this study was to compare the biomechanical stability of monocortical and bicortical locking osteosynthesis in quasi-static and dynamic 4-point bending tests of composite third metacarpal bone (4th Gen third metacarpal, Sawbones, Malmö, Sweden) fixed with 7-hole locking plate (XXS System, Biotech-Ortho, Wright, Memphis, TN). The tests to determine quasi-static yield and bending strength as well as fatigue strength were conducted in 4 groups of 10 samples after creating standardized mid-shaft transverse osteotomies using a diamont belt grinder (0.3 mm saw blade). The force applied was the dorsal apex loading, similar to the forces applied to metacarpals during normal finger flexion and extension.In the quasi-static testing, no plate breakage was observed in each group. All metacarpals broke at their thinnest part. The average bending strength of the bicortical samples (10.54 ± 0.998 Nm) was significantly higher comparing to the monocortical samples (8.57 ± 0.894 Nm) (P < .001).In the dynamic loading test, all constructs (8 monocortical samples and 7 bicortical) that failed broke at the osteotomy site and the average fatigue strength did not differ in both groups.Consequently, a unicortical plating method may provide adequate strength and stability to metacarpal fractures based on the results of the cyclical loading representative of in vivo loading.

Bone plates for osteosynthesis are subject to biomechanical testing for safety and regulatory purposes. International standards applicable for those devices are designed for bone plates used in the surgical fixation of the skeletal system but not necessarily for all device variants available. We intend to summarize the test methods and parameters presented in the literature to evaluate bone plates in a clinical environment, especially for modern anatomically shaped implants. We conducted a systematic review on published biomechanical studies for lower and upper extremities (clavicle, humerus, ulna, radius, metacarpal, femur, tibia, fibula, metatarsal). The search process led to the identification of 159 relevant articles containing 330 individual tests, which were analyzed concerning various test criteria including test methods and parameters per bone segment for static and dynamic loading tests, as well as number of cycles, chosen bone model and outcome variables. The biomechanical literature for bone plates is diverse, inconsistent and heterogeneous. Test methods are not commonly applied per bone plate location and test parameters are not uniformly specified and displayed. They vary in particular for bending and torsion tests as well as for the number of loading cycles for dynamic testing. Outcome variables are not commonly applied nor defined. Consequently this paper is the first in a planned chronological series of three to identify the need (this publication), to develop a systematic procedural approach (2. publication) and to apply the process exemplary on a bone plate sample (3. publication).

Open reduction and fixation of low condylar fractures of the mandible can be achieved by many osteosynthesis systems that differ in size, shape, and site of placement according to the surgical approach. We investigated the maximum load and rigidity of 4 osteosynthesis systems: the standard double 4-hole straight miniplates, the inverted y-miniplate (with and without self-drilling screws), and the TriLock Delta condyle trauma plate. The standard double 4-hole straight miniplate osteosynthesis achieved the best fixation and resistance in view of a mean (SD) maximum load of 539.8 (100.2)N, followed by the inverted y-miniplate with the self-drilling screws (246.5 (23.8)N), the inverted y-miniplate with standard screws (242.4 (27.2)N), and finally the TriLock Delta plate (167.4 (39.2)N). Analysis of the slope of the force-displacement diagram from 80N to 100N in each group showed that the TriLock Delta miniplate had the highest values for rigidity (17.3 (5.1)N/μm), followed by the inverted y-miniplate groups with self-drilling screws (14.1 (6.4)N/μm), and with standard screws (12.6 (2.5)N/μm). The double 4-hole straight miniplate osteosynthesis had the lowest rigidity (8.7 1.4)N/μm). Despite the significant difference in the maximum load between the double 4-hole miniplates and other investigated osteosynthesis patterns, all groups had sufficient load for the fixation of low condylar fractures of the mandible when postoperative bite forces and the slowly increasing voluntary clenching during healing were considered., (Copyright © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Purpose: A biomechanical study was performed to test the hypothesis that a new anatomically preformed, thinner, soft-tissue protecting plate system for distal humeral fractures (Tifix®-hybridplate [HP]) would show comparable results in the quasi-static and dynamic testings compared to two conventional implants: The 3.5-mm reconstruction plate (RP) providing primary stability with normal bone mineral density (BMD), and a multidirectional locking plate (Tifix(®)-plate [P]) which can be used with poor bone quality., Methods: The Tifix(®)-HP was developed by the working group. The biomechanical testing was performed on a C2-fracture-model in 24 synthetic humeri. Three groups, each with eight bone-implant-constructs, were analysed in quasi-static and dynamic tests., Results: The quasi-static measurements showed that under extension loading both locking plates (Tifix(®)-P, Tifix(®)-HP) were significantly stiffer than the reconstruction plate, and that the Tifix(®)-HP had a significantly lower stiffness than the two other implants under flexion loading. In the dynamic tests the Tifix(®)-P allowed significantly less fracture motion compared to the Tifix(®)-HP and the reconstruction plate. In an osteopaenic bone model locking plates failed only under much higher dynamic force than the reconstruction plate. The reconstruction plate and the Tifix(®)-P always failed through screw loosening, whereas the newly developed Tifix(®)-HP showed screw loosening in only one third of cases., Conclusion: The hypothesis that the newly designed plate system showed comparable results in the quasi-static and dynamic tests compared to the conventional implants with a significantly lower implant volume and thickness was confirmed.