Design and Validation of a Smile‐Necklace Plate for Treating Inferior Patellar Pole Avulsion Fractures: A Review and Hypothesis

Abstract

The patella's inferior pole transmits force generated by contraction of the quadriceps muscle to the tibial tuberosity through the attached patellar ligament, thus completing knee extension. Therefore, fractures of the patella's inferior pole disrupt the coherence of mechanical transmission in the lower extremities. There appears to be no consensus among trauma centers regarding the treatment of infrapatellar pole fractures, primarily because there is no consistent design or application of internal fixation for this type of fracture. We designed a new internal implant similar to the smile necklace based on our previous study. This smile‐necklace plate (SNP) has the advantage of both plate fixation and tension‐band wiring fixation, permitting early rehabilitation, especially in osteoporotic comminuted infrapatellar pole fractures. Finite element analysis helped verify the biomechanical advantages of the SNP in comparison with existing studies. Hence, this novel implant is a promising treatment option for inferior pole patellar fractures.

Computational evaluation of wire position using separate vertical wire technique and candy box technique for the fixation of inferior pole patellar fractures: a finite element analysis

“…The elastic modulus and Poisson’s ratio of bones and steel wires in the model were defined based on previous research (as shown in Table 1 ) ( Du et al, 2022 ). Frictional contact was set between the periphery of the patella and bone tunnel wire, as well as between the patella and vertical wire, with a friction coefficient of 0.2 ( Zhu et al, 2022 ). The friction coefficient of the fractured end of the inferior pole of the patella was set to 0.45 ( Chang et al, 2018 ; Demirtaş and Kati, 2023 ).…”

“…However, when steel wires are inserted into the fractured comminuted area at the inferior pole, it can result in weak fixation and potential displacement of small bone fragments. This increases the risk of internal fixation failure and nonunion ( Zhu et al, 2022 ; Fan et al, 2023 ).…”

Candy box technique for the fixation of inferior pole patellar fractures: finite element analysis and biomechanical experiments

“…Various parameters of the bone and wire in the 3D model were defined, such as the elastic modulus and Poisson’s ratio (as shown in Table 1 ) [ 4 ]. Three types of frictional contacts were set: the contact between the periphery of the patella and encircling wire, contact between the patella and vertical wire with a friction coefficient of 0.2 [ 23 ], and contact between fracture ends with a friction coefficient of 0.45 [ 24 , 25 ]. The portion where the wire passed through the patella was set as “bonded” (i.e., there was no relative displacement between them).…”