Guidelines for the clinical application of the LCP

Distal femur fractures can exhibit extensive comminution, and open fractures may result in bone loss. These injuries are under high mechanical demands when stabilized with a lateral locked plate (LLP), and are at risk of non-union or implant failure. This study investigates the optimal LLP screw configuration for distal femur fractures with a large metadiaphyseal gap of 5 cm.

A finite element (FE) model, validated against experimentally measured strains and displacement, evaluated pull-out forces and stress concentration on typical implants under clinical conditions corresponding with the 10 % point during the stance phase of the gait cycle.

Maximum stress was up to 83 % less when the ratio (Cp) between the proximal screw-distribution-length and the distance of the first screw to the fracture was less than 0.2; maximum pull-out force was 99 % less when this ratio was higher than 0.4.

Screw configuration based on either normal or osteopenic bone quality plays an important role in determining the risk of construct failure for a major (50 mm) distal femoral metadiaphyseal segmental defect. This study provides valuable information when planning definitive fixation for distal femur fractures with extensive comminution or segmental bone defects, to mitigate the risk of implant failure and subsequent nonunion.

La reconnaissance d’une responsabilité repose sur 3 éléments : une faute, un dommage, et un lien de causalité direct et certain entre les deux. Dans la recherche de ces éléments, l’expert doit faire abstraction de ses premières impressions, et analyser précisément les éléments qui pourraient paraître évidents en l’absence de cette analyse. Dans cette affaire, un retour aux connaissances basiques de physique et de trigonométrie a permis de mettre en évidence l’impossibilité de lien entre la kinésithérapie réalisée et la rupture du matériel. La responsabilité du kinésithérapeute n’a donc pas été retenue, ce qui a permis de chercher ailleurs les causes d’une rupture de plaque d’ostéosynthèse.

Distal femoral fractures are fractures associated with high rates of morbidity and mortality, affecting to three different groups of individuals: younger people suffering high-energy trauma, elderly people with fragile bones and people with periprosthetic fractures around previous total knee arthroplasty. They have been classically treated with conventional plates and intramedullary nails and more recently with locked plates that have increased their indications to more types of fractures. The main objective of the present work is the biomechanical study, by means of finite element simulation, of the stability achieved in the osteosynthesis of femoral fractures in zones 4 and 5 of Wiss, by using locked plates with different plate lengths and different screw configurations, and analysing the effect of screw proximity to the fracture site. A three dimensional (3D) finite element model of the femur from 55-year-old male donor was developed, and then a stability analysis was performed for the fixation provided by Osteosynthesis System LOQTEC® Lateral Distal Femur Plate in two different fracture zones corresponding to the zones 4 and 5 according to the Wiss fracture classification. The study was focused on the immediately post-operative stage, without any biological healing process. The obtained results show that more stable osteosyntheses were obtained by using shorter plates. In the cases of longer plates, it results more convenient disposing screws in a way that the upper ones are closer to fracture site. The obtained results can support surgeons to understand the biomechanics of fracture stability, and then to guide them towards the more appropriate osteosynthesis depending on the fracture type and location.

The locking compression plate (LCP) and screw sets are widely used as internal fixator assemblies to treat long bone fractures. However, the surgeon's critical challenge is choosing the implant set (plate and screws) for each patient. The present study introduces a parametrized simulation-based optimization algorithm for determining an LC system with the best bone-implant stability. For this purpose, a three-dimensional fractured bone supported by an LC system was generated, and the discrete genetic optimization approach was utilized to design the optimum implant. Initially, an algorithm was developed to optimize the optimum layouts for different numbers of screws. For the middle third transverse fracture, six screws were selected as the optimal number of the screws. In a second stage, the model was run to determine the best LC plate dimensions for desired fractured bones. Finally, optimal plates were identified for simple middle third transverse, 60° middle third oblique, and distal third transverse femoral fractures. The results of these simulations and those for other fracture types can be exploited to achieve improved surgical outcomes by selecting proper implants and screws configurations.

Because of the irregular shape of the scapula and the different types of fractures, a standard internal fixation device is lacking in clinical practice, even though there are many options available. This study aimed to compare the therapeutic efficacy of titanium anatomic and reconstructive plates for extra-articular fractures of the scapula (Miller types IIb, IIc, and IV).

A retrospective study of 41 patients who underwent treatment for extra-articular fractures of the scapula between March 2017 and March 2020 was conducted. Patients were divided into 2 groups based on the fixation device: titanium anatomic plate group (20 patients) and titanium reconstructive plate group (21 patients). After follow-up for 12-18 months, the general characteristics, perioperative characteristics, postoperative follow-up findings, and imaging data of the 2 groups were compared.

The surgical procedures were uneventful in both groups. The anatomic plate group significantly outperformed the reconstructive plate group with respect to surgical duration and intraoperative blood loss (P < .001). At 3-month postoperative follow-up, the Constant-Murley score (P = .026), shoulder flexion range of motion, and shoulder abduction range of motion in the anatomic plate group were all significantly better than those in the reconstructive plate group (P < .001). The postoperative Western Ontario Shoulder Instability scores of the 2 groups were similar. Imaging showed functional recovery and stable and reliable fixation in both groups. Time to bone union was similar in both groups (9.10 ± 1.25 weeks in anatomic plate group and 9.24 ± 1.41 weeks in reconstructive plate group, P = .742). No complications occurred in any patient, such as fixation failure, instability, or bone nonunion.

Surgeons should favorably consider titanium anatomic plates for the treatment of extra-articular scapular fractures owing to their clear efficacy associated with a shorter surgical time, less intraoperative blood loss, better fixation, and rapid short-term functional recovery.

This study investigated the effects of screw hole merging, thread removal, and screw hole offset on the mechanical properties of locking plates.

Finite element models were used to develop the optimal design of the merged holes. Four titanium locking plates with different hole designs were analyzed. Type I had threaded round holes. Type II had merged holes. Type III had merged holes with partial thread removal. Type IV had threaded offset holes. Mechanical experiments similar to finite element analyses were conducted and compared. Screw bending tests were used to assess the screw holding power.

Finite element analyses showed the optimal merging distance between two round screw holes was 3.5 mm with 2/3 circumferences in each hole. The stresses of types II and III were respectively 6.42% and 7.33%, lower than that of type I. The stress of type IV was 1.66% higher than that of type I. In the mechanical tests, the fatigue lives of types II and III were respectively 3.86 and 7.16 times higher than that of type I. The fatigue life of type IV was 37% lower than that of type I. The differences in the bending strengths of screws were insignificant.

Merging holes could mitigate screw hole stress and increase the fatigue lives of the plates significantly. Partial thread removal could further improve the fatigue life. Merging holes and thread removal did not decrease the screw holding power significantly. The fatigue lives were significantly decreased in plates with offset holes.