Conformational variations of the medial epicondyle of the humerus: A case study of fusion anomaly on dry bones.

The estimation of a biological profile in biological anthropology is a central point in the study of human remains. To specify this profile, the observation of variations, and pathologies on the skeleton is a tool that makes an individual unique. In this research, the focus was on the distal part of the humerus. Through the study of five individuals from an osteo-archaeological collection, conformational anomalies of the medial epicondyle of the humerus were highlighted. The aim is to describe them and to propose an etiology of appearance. For this purpose, observation of the rest of the skeleton was carried out, in order to search for the presence of other variations, in particular anomalies of fusion of secondary ossification centers. Overall, a non-fusion of the medial epicondyle of the humerus, two fused medial micro-epicondyles and two supplementary fusions were observed. These are very rare anomalies, with an estimated prevalence of 0.7%. Conformational abnormalities of this area can lead to pain. Therefore, medical imaging for diagnostic purposes may be available: useful data for antemortem documentation in case of a disturbing disappearance. Following the study of the entire skeleton, a common etiology for these different conformations cannot be proposed. However, two categories of etiologies can be proposed: a congenital anomaly and a developmental anomaly with an environmental influence (mechanical or deficiency). The new knowledge of this area will enrich the use of individualization factors, especially in the context of forensic anthropology.

Treatment results of adult patients with primary bone tumours of the humerus with the use of the oncological modular endoprosthesis.

AIM OF THE STUDY: Primary bone tumours are relatively rare, but their diagnosis and treatment is difficult and connected with a high risk of complications. The goal of this report is a retrospective evaluation of outcomes in patients with primary tumours of the humerus treated in our centre with the use of modular endoprosthetic reconstruction. MATERIAL AND METHODS: Currently, surgical treatment is a standard procedure for local therapy, with wide tumour-free margin resection after a planned multidisciplinary and individualised strategy of tumour management based on the diagnostic biopsy result. The best option for patients to avoid disability is simultaneous surgical reconstruction aiming to spare the limb and its functionality. RESULTS: In this report, we present the results of treatment of our 11 adult patients suffering from primary bone tumours of the humerus, who have undergone wide bone resection followed by reconstruction with the use of a modular MUTARS® endoprosthesis. CONCLUSIONS: The study showed that prosthetic reconstruction of the resected humerus due to a primary bone tumour is safe and acceptable for patients; despite the fact that limitation of active abduction of the shoulder is up to 20 grades, this surgical procedure provides satisfactory limb function.

Reverse Shoulder Megaprosthesis for Massive Proximal Humeral Bone Loss in Fracture Outcome Settings: A Report of Two Cases and Literature Review.

In trauma settings, including the management of outcomes, there is no consensus on the most appropriate reconstructive method in the presence of severe bone loss of the proximal humerus. The objective of this report is to evaluate the short-term functional outcomes of two patients in whom reverse shoulder megaprosthesis was used to treat the failure of trauma surgery with severe bone loss. The secondary objective was to compare the results obtained with the literature regarding the use of megaprosthesis in shoulder trauma surgery. The patients showed a satisfying functional recovery and increased quality of life. At the 12-month follow-up, no complications occurred. Regarding the risk of complications, especially the risks of mobilization of the megaprosthesis, the CT-based intraoperative navigation system optimizes the configuration of the screw for the initial fixation of the glenoid component. Shoulder megaprosthesis appears to be a viable option not only in oncologic surgery but also in cases of failed trauma surgery. The functional results, considering functional score and range of motion, are encouraging and allow patients to improve their quality of life.

Design and validation of a novel 3D-printed glenohumeral fusion prosthesis for the reconstruction of proximal humerus bone defects: a biomechanical study.

Background: All available methods for reconstruction after proximal humerus tumor resection have disadvantages, and the optimal reconstruction method remains uncertain. This study aimed to design a novel 3D-printed glenohumeral fusion prosthesis and verify its feasibility and safety using biomechanical methods. Methods: We verified the feasibility and safety of the 3D-printed glenohumeral fusion prosthesis by finite element analysis and biomechanical experimentation. In the finite element analysis, three reconstruction methods were used, and displacement and von Mises stress were observed; on this basis, in the biomechanical experiment, models constructed with sawbones were classified into two groups. The force‒displacement curve of the 3D-printed prosthesis was evaluated. Results: In terms of displacement, the finite element analysis showed greater overall stability for the novel prosthesis than traditional glenohumeral joint arthrodesis. There was no obvious stress concentration in the internal part of the 3D-printed glenohumeral fusion prosthesis; the stable structure bore most of the stress, and the force was well distributed. Adding lateral plate fixation improved the stability and mechanical properties of the prosthesis. Furthermore, the biomechanical results showed that without lateral plate fixation, the total displacement of the prosthesis doubled; adding lateral plate fixation could reduce and disperse strain on the glenoid. Conclusion: The design of the 3D-printed glenohumeral fusion prosthesis was rational, and its stability and mechanical properties were better than those of traditional glenohumeral joint arthrodesis. Biomechanical verification demonstrated the feasibility and safety of this prosthesis, indicating its potential for proximal humerus bone defect reconstruction after tumor resection.

A Retrospective Study of the Functional Outcomes in Patients with Proximal Humeral Bone Defect after Shoulder Fusion or Prosthetic Replacement.

AIMS: The reconstruction of proximal humeral defects resulting from tumor resection is challenging. The purpose of this work was to retrospectively study the functional outcomes in patients with large bone defects after the resection of proximal humeral tumors. METHODS: We performed a retrospective analysis of 49 patients with malignant or aggressive benign tumors in the proximal humerus at our institution between 2010 and 2021. Forty-nine patients were included in the study (prosthetic replacement, n = 27; shoulder arthrodesis, n = 22). The mean follow-up was 52.8 months (range, 14-129 months). The factors evaluated included the Musculoskeletal Tumor Society (MSTS) functional score, Constant Murley Score (CMS), and complications. RESULTS: Of the 49 patients enrolled in the study, 35 were disease-free by the time of the latest follow-up, and 14 died because of the disease. Adjuvant therapies and medical comorbidities were similar between the two groups. Osteosarcoma was the most common abnormality among all the patients. The mean MSTS scores for surviving patients in the prosthesis and arthrodesis groups were 57.4% and 80.9%, respectively. The mean CMS score for the surviving patients in the prosthesis group was 43.47, and it was 61.44 for arthrodesis cases. Patients with shoulder arthrodesis demonstrated evidence of bony union at a mean of 4.5 months. CONCLUSIONS: Shoulder arthrodesis is a reliable reconstructive procedure in patients with large bone defects after the resection of proximal humeral tumors for pediatric osteosarcoma patients. Moreover, prosthetic replacement with anatomical implants results in poor function in older metastasis patients with large bone defects and resection of the deltoid muscle.

Experimental characterization and micromechanical modeling of the elastic response of the human humerus under bending impact.

This paper investigates the characterization and numerical modeling of the elastic behavior of the human humerus bone using a recently developed micromechanical approach coupled to nanoindentation measurements. At first, standard three-point bending experiments were conducted under low static loading, using several humerus diaphysis in order to identify the apparent elastic modulus of the bone in static regime. Then, a drop tower impact experiment was used on the same set of humerus diaphysis specimens, in order to assess the elastic modulus in dynamic regime. These measurements will be used as reference bases for comparison purpose. The originality of this work, lies in the coupling between a two-phase micromechanical approach based on Mori-Tanaka homogenization scheme for cylindrical voids and nanoindentation measurements of the elastic modulus of the bone matrix phase. This model has been implemented using a user defined material subroutine VMAT in ABAQUS© Explicit code. The bone mechanical response prediction using the proposed methodology was validated against previous standard experimental data. Finally, it was shown that the numerical predictions are consistent with the physical measurements obtained on human humerus via the good estimation of the ultimate impact load.