Comparison of biomechanical characteristics in treatment of distal humerus fracture using different fixation plates: A finite element study

Biomechanical Design Optimization of Distal Humerus Fracture Plates: A Review

The goal of this article was to review studies on distal humerus fracture plates (DHFPs) to understand the biomechanical influence of systematically changing the plate or screw variables. The problem is that DHFPs are commonly used surgically, although complications can still occur, and it is unclear if implant configurations are always optimized using biomechanical criteria. A systematic search of the PubMed database was conducted to identify English-language biomechanical optimization studies of DHFPs that parametrically altered plate and/or screw variables to analyze their influence on engineering performance. Intraarticular and extraarticular fracture (EAF) data were separated and organized under commonly used biomechanical outcome metrics. The results identified 52 eligible DHFP studies, which evaluated various plate and screw variables. The most common plate variables evaluated were geometry, hole type, number, and position. Fewer studies assessed screw variables, with number and angle being the most common. However, no studies examined nonmetallic materials for plates or screws, which may be of interest in future research. Also, articles used various combinations of biomechanical outcome metrics, such as interfragmentary fracture motion, bone, plate, or screw stress, number of loading cycles to failure, and overall stiffness (Os) or failure strength (Fs). However, no study evaluated the bone stress under the plate to examine bone "stress shielding," which may impact bone health clinically. Surgeons treating intraarticular and extraarticular distal humerus fractures should seriously consider two precontoured, long, thick, locked, and parallel plates that are secured by long, thick, and plate-to-plate screws that are located at staggered levels along the proximal parts of the plates, as well as an extra transfracture plate screw. Also, research engineers could improve new studies by perusing recommendations in future work (e.g., studying alternative nonmetallic materials or "stress shielding"), clinical ramifications (e.g., benefits of locked plates), and study quality (e.g., experimental validation of computational studies).

Comparative study of a Y- anatomical and innovative locking plate versus double plate for supracondylar humeral fracture

INTRODUCTION

There is no "gold standard" for the type of plate to be used for distal extra-articular humeral fractures; the most used is plating of each column. The objective was to evaluate the short-term clinical and radiological results of a Y- anatomical and innovative locking plate (YALP).

HYPOTHESIS

The hypothesis is: this anatomical and innovative locking plate will produce satisfactory and reliable results on extra-articular distal humerus fracture superior to double plate fixation.

MATERIALS AND METHODS

In a retrospective observational multicenter study, all patients with a distal humerus fracture type 13 A2.2 according to AO classification fixed with a new Y-plate (YALP) were compared to the results of double plate fixation for the same type of fracture. With a follow-up of more than 12 months, the objective and subjective clinical elbow criteria as well as the overall function of the upper limb and radiological assessment were collected.

RESULTS

With an average follow up of 24±11 months, 26 patients met the inclusion criteria and received a YALP and 24 patients received double plate. All patients whose fracture had healed except one were pain-free (mean VAS 0.3±0.6). All patients had good subjective results (mean SEV 96%±4). Elbow function was excellent (mean total MEPS 96±4) with normal triceps strength (23/24 patients had a triceps strength graded 5/5 and one patient 4/5) and range of motion (flexion 139±8, extension -7±8 and pronosupination greater than 155 degrees). The operating time was shorter in the YALP group (84 ± 23minutes versus 97 ± 28minutes, p=0.03). The double plate group had more complications; the overall complication rate was significantly higher (p=0.02) in the double 90-degree plate group (12/24, 50%) with four nonunions, four symptomatic ulnar nerves, three hardware removals for pain and one radial nerve injury versus 5/26 complications (19%, p=0.02) in the Y-plate group: one iliac graft for nonunion, 1 plate removal due to functional discomfort, 1 twisted YALP, 1 broke interfragmentary screw and one symptomatic ulnar nerve. DASH, SEV, MEPS scores and flexion-extension range were better in the YALP group.

DISCUSSION

YALP produces satisfactory results in supracondylar fractures of the distal humerus. The results of YALP appear to be better than the results with two 90° plates for the same fracture type with a shorter operative time and easier management of fractures with proximal diaphyseal extension.

LEVEL OF EVIDENCE

III; case control study.

Full Regional Creep Displacement Map of Articular Cartilage Based on Nanoindentation Array

The elucidation of the mechanisms underlying articular cartilage lesions poses a formidable challenge in the field of cartilage repair. Despite significant strides in cartilage mechanics research, the region-dependent creep properties of articular cartilage remain elusive. In this study, we employ depth-sensing indentation tests to experimentally determine the creep properties of four distinct regions of articular cartilage, thereby unveiling a region-dependent full map of creep parameters. The measured creep displacement-time response curves indicate that the creep properties of the articular cartilage exhibit a clear regional correlation. Accordingly, the full regional creep map of articular cartilage is experimentally constructed for the first time. The correlation between the microstructures and the creep properties of cartilage in different regions is revealed. A three-parameter model is established to describe the creep velocity-displacement response of cartilage. Raman spectra reveal that the proteoglycan content is positively correlated with creep properties. The Raman shift directly indicates diverse residual stresses in different microregions. The obtained data facilitate a deep understanding of the potential creep dependent damage mechanism of cartilage and the further development of artificial cartilage materials.