Development of an additively-manufactured functionally-graded expandable implant via the application of the adaptive response surface method: feasibility study on intramedullary humerus nail.

The paper introduces the concept of the rational design of a deployable humeral intramedullary nail plug based on a honeycomb structure used for the surgical treatment of humeral shaft fractures. The concept serves for to restore the axial alignment of bone fragments and to maintain stability via bone-nail friction and locking screws. The design nail plug was gained by optimisation process the Latin Hypercube Sampling Design algorithm and Multi-Objective Genetic Algorithm. It was shown that we can use statistical shape function combined by 3 D printing for designing of a new rationally designed implants.

NON-UNIONS AFTER FIXATION OF HUMERAL FRACTURES USING HACKETHAL'S BUNDLE NAILING TECHNIQUE

ABSTRACT Objective: The aim of the study was to identify factors contributing to the development of non-union after fixation of diaphyseal humeral fractures using Hackethal's intramedullary nailing technique. Methods: In the time period from 2001 to 2010 156 patients with diaphyseal humeral fractures were treated surgically using Hackethal's technique. Six of them (3.8%) developed non-union. This group included three women and two men aged 63-69 years and one woman aged 37 years. The following parameters of the patients were recorded: age, gender, comorbidities, substance abuse, mechanism of injury, fracture type and location according to the AO/ASIF classification, and the operative technique. Results: A non-union developed in six patients treated with Hackethal´s method (3.8%). Five of six non-unions (83%) were observed in patients in their sixties. In the subgroup of sexagenarians, non-union developed in 20.8% of surgically treated patients, as compared to 3.8 % in entire group. In the union group, fractures have been caused by high energy trauma in 52% of patients. In patients who developed non-union, high energy trauma caused 67% of fractures. With correct surgical technique the development of a non-union was observed in 0.7% of patients, with incorrect technique in 35.7% (p<0.001). Conclusion: Treatment of diaphyseal humeral fractures with Hackethal's intramedullary elastic bundle nailing resulted in an overall high union rate. Factors contributing to the development of non-union were extension of this method to AO type B3 and C fractures and technical imperfection during implantation. Level of Evidence III, Prospective, Case-Control Study.

Computed modeling of humeral mid-shaft fracture treated by bundle nailing.

Elastic bundle nailing is a method for simple humeral mid-shaft fracture osteosynthesis. The aim of our subsequent numerical simulations was to find out torsional and bending stiffness of an elastic bundle nailed humerus. Parametrical 3D numerical model was developed. The diameter of nails was the varying parameter of 1.8, 2.5, 3 and 4 mm. From our results can be seen that the bending stiffness in bundle nailing technique does not depend on nail diameter. On the contrary the torsional stiffness does highly depend on nail diameter. The dependency of the maximal stress on a nail diameter during bending and torsion of the humerus is non-linear. It can be seen that the higher diameter is used the higher stress occurs. Achieved results allow us for the recommendation of optimal nail diameter for this method, which lies between 2 and 3 mm.

NON-UNIONS AFTER FIXATION OF HUMERAL FRACTURES USING HACKETHAL'S BUNDLE NAILING TECHNIQUE.

OBJECTIVE: The aim of the study was to identify factors contributing to the development of non-union after fixation of diaphyseal humeral fractures using Hackethal's intramedullary nailing technique. METHODS: In the time period from 2001 to 2010 156 patients with diaphyseal humeral fractures were treated surgically using Hackethal's technique. Six of them (3.8%) developed non-union. This group included three women and two men aged 63-69 years and one woman aged 37 years. The following parameters of the patients were recorded: age, gender, comorbidities, substance abuse, mechanism of injury, fracture type and location according to the AO/ASIF classification, and the operative technique. RESULTS: A non-union developed in six patients treated with Hackethal´s method (3.8%). Five of six non-unions (83%) were observed in patients in their sixties. In the subgroup of sexagenarians, non-union developed in 20.8% of surgically treated patients, as compared to 3.8 % in entire group. In the union group, fractures have been caused by high energy trauma in 52% of patients. In patients who developed non-union, high energy trauma caused 67% of fractures. With correct surgical technique the development of a non-union was observed in 0.7% of patients, with incorrect technique in 35.7% (p<0.001). CONCLUSION: Treatment of diaphyseal humeral fractures with Hackethal's intramedullary elastic bundle nailing resulted in an overall high union rate. Factors contributing to the development of non-union were extension of this method to AO type B3 and C fractures and technical imperfection during implantation. Level of Evidence III, Prospective, Case-Control Study.

Fractures of the scapular neck: diagnosis, classifications and treatment.

PURPOSE: Fractures of the scapular, or glenoid, neck are strongly debated in the relevant literature. Analysis of the respective studies, however, revealed a considerable confusion in terms of definition, terminology and diagnosis. In addition, there are few studies, primarily case reviews, dealing in detail with these fractures. The aim of this article is to present detailed information about fractures of the scapular neck, based on the analysis of our own experience and of the published literature. MATERIAL AND METHODS: Our group of 17 fractures of the scapular neck comprised 14 men and three women, with a mean age of 38 years (range, 24-55). The authors diagnosed four fractures of the anatomical neck, nine fractures of the surgical neck and five trans-spinous fractures of the neck. Of these 17 scapular neck fractures, six fractures were treated non-operatively, and 11 fractures were operated on via the posterior Judet approach. The mean follow-up was 4.9 years (range, 1-11). RESULTS: Fractures in all six non-operatively treated patients healed without complications in the anatomical position and with full function of the shoulder. In 11 operatively treated patients, all fractures of the scapula and clavicle healed within three months. In nine cases the function of the shoulder was subjectively and objectively assessed as normal, and in the remaining two cases as fair. CONCLUSION: The term "scapular, or glenoid, neck" covers three different types of fractures, i.e., fracture of the anatomical neck, fracture of the surgical neck and trans-spinous neck fracture. Fractures of the surgical neck are divided into stable, fractures with rotational instability and fully unstable fractures, depending on the integrity of the coracocacromial and coracoclavicular ligaments. Accurate diagnosis of fractures of the scapular neck requires 3D CT reconstructions. Undisplaced or minimally displaced fractures may be treated non-operatively, markedly displaced fractures constitute an indication for osteosynthesis via the Judet approach.