Medical diagnosis of cubital tunnel syndrome ameliorated with thrust manipulation of the elbow and carpals

This case report describes the effectiveness of thrust manipulation to the elbow and carpals in the management of a patient referred with a medical diagnosis of cubital tunnel syndrome (CuTS). The patient was a 45-year-old woman with a 6-week history of right medial elbow pain, ulnar wrist pain, and intermittent paresthesia in the ulnar nerve distribution. Upon initial assessment, she presented with a positive elbow flexion test and upper limb neurodynamic test with ulnar nerve bias. A biomechanical assessment of the elbow and carpals revealed a loss of lateral glide of the humerus on the ulna and a loss of palmar glide of the triquetral on the hamate. After the patient received two thrust manipulations of the elbow and one thrust manipulation of the carpals over the course of four sessions, her pain and paresthesia were resolved. This case demonstrates that the use of thrust manipulation to the elbow and carpals may be an effective approach in the management of insidious onset CuTS. This patient was successfully treated with thrust manipulation when joint dysfunction of the elbow and wrist were appropriately identified. This case report may shed light on the examination and management of insidious onset CuTS.     

Tissue resistance of the tension-free procedure: What about healing?

The aim of our work was to objectify and quantify the mechanical benefits of healing with regards to tearing meshes off of tissues and maximal resistance after cicatrization. In vivo, we tested the mechanical gain in resistance by healing after implantation of a Prolene® mesh. We measured the value of forces when traction was exerted until mobilization at different stages of cicatrization. Resistance increased progressively at the beginning of tissue inclusion. A maximal plateau was reached around the 25th day. It is important to understand the role of sustaining and reinforcement we hope tissue integration of the mesh will play. We can thus adapt procedures to have the best kinetics and maximal resistance of montages. Study of the kinetics and maximal plateau allows us to make the best clinical recommendations.     

改良股骨髓内钉治疗不稳定股骨颈骨折的生物力学研究

目的将改良股骨髓内钉与动力髋螺钉（DHS）用于不稳定型股骨颈部骨折模型,探讨改良股骨髓内钉对股骨颈部骨折的治疗作用及力学性能优劣。方法男性健康成人股骨成对防腐尸骨湿标本左右侧各5根,均于股骨颈基底部锯断,制成pauwel角为60°的不稳定股骨颈骨折内固定模型,模拟髋关节动载荷,对两种治疗方式在髋载荷下的压缩试验及抗扭转性能进行测评。结果髓内钉组及DHS组对髋载荷的压缩反应张力侧均表现为张应变和张开位移,但髓内钉组的对抗断端分离移位能力大大优于DHS组;在压力侧,DHS组的断端间相应靠近嵌插反应较髓内钉实验组大,对不稳定骨折而言,这种反应有使压力侧骨折块挤压移位的可能。抗扭转性能DHS组显然不如髓内钉组强大。结论改良股骨髓内钉用于不稳定型股骨颈骨折的固定,其力学性能可保证骨折端的复位和固定要求,固定效果明显优于DHS。     

Effects of compressive loading on biomechanical properties of disc and peripheral tissue in a rat tail model

Intervertebral disc degeneration induced by mechanical compression is an important issue in spinal disorder research. In this study, the biomechanical aspect of the rat tail model was investigated. An external loading device equipped with super-elastic TiNi springs was developed to apply a precise load to the rat tail. By using this device, rat tail discs were subjected to compressive stress of 0.5 or 1.0 MPa for 2 weeks. Discs in the sham group received an attachment of the device but no loading. After the experimental period, first the intact tail with peripheral tissues (PT) such as tendon and skin and then the retrieved disc without PT were subjected to a uniaxial tension–compression test; biomechanical characteristics such as range of motion (ROM), neutral zone (NZ), and hysteresis loss (HL) were evaluated. Furthermore, the load-bearing contribution of PT in the intact tail was estimated by comparing the load–displacement curves obtained by the mechanical tests performed with and without PT. The experimental findings revealed that the continuous compressive stress induced reduction in disc thickness. The intact tail demonstrated decreases in ROM and NZ as well as increases in HL. On the other hand, the retrieved disc demonstrated increases in ROM, NZ, and HL. Further, a significant increase in the load-bearing contribution of PT was indicated. These findings suggest that the load-bearing capacity of the disc was seriously deteriorated by the application of compressive stress of 0.5 or 1.0 MPa for 2 weeks.     

Design and biomechanical properties of dental implant pore structure based on three-dimensional finite element analysis北大核心

BACKGROUND: Studies have shown that the elastic modulus can be changed by changing the pore internal unit structure when designing porous implants, providing a new way to better balance implant strength and elastic modulus. OBJECTIVE: To analyze dental implant biomechanical properties with different micro pore structures by finite element analysis so as to elucidate the effects of different micro pore structures on the surrounding bone stress and implant physical properties. METHODS: A mandibular model and three finite element models of dental implants with different pore structures (conventional structural pores, composite structural pores, and G7 structural pores) were built by CT scanning with porosity of 40%, the thickness of the porous layer of 1.2 mm, and the pore size of 0.45 mm. The ultimate force state was simulated to apply load to each model, which was operated by ANSYS finite element software and analyzed by surrounding bone stress and strain of the implants. RESULTS AND CONCLUSION: (1) When implants were subjected to the ultimate force, the maximum values of effector forces such as 38.324, 56.574, 64.694 MPa for conventional structure, composite structure and G7 structure dental implants on the surrounding cortical bone were respectively 1.836, 10.221, 9.439 MPa, and the maximum values of effector forces such as implants were 156.38, 476.23, 457.76 MPa. The maximum surrounding bone stress of the composite structure implant was within the range of promoting osseointegration. (2) When only lateral forces were applied to the implants, the maximum strain values of dental implants placed in the conventional structure, composite structure and G7 structure were 2.222 9×10-2, 1.661 9×10-2, 3.210 9×10-2 mm/mm. When only axial forces were applied to the implants, the maximum strain values of dental implants placed in the conventional structure, composite structure and G7 structure were 2.266 2×10-3, 1.844 6×10-3, 2.971 5×10-3 mm/mm, indicating that when subjected to lateral static load and axial load, the strain of the composite structure implant was smallest and the micro-movement was small, which helped to improve the osseointegration effect. (3) The results showed that the surrounding bone stress changed significantly with the change of pore unit cell structure inside the porous implant, and the mechanical properties of the implant also changed, and the change of unit cell structure shape of the porous structure on the implant surface significantly affected the elastic modulus and the mechanical properties of the implant. Dental implants with a composite pore structure had better biomechanical properties compared with conventional constructs and G7 constructs. © 2022, Publishing House of Chinese Journal of Tissue Engineering Research. All rights reserved.     

Plate osteosynthesis of the mandibular condyle

The aim of this study is to evaluate and compare the biomechanical stability of various osteosynthesis materials for mandible condylar-process fractures. On 160 porcine mandibles, four different monocortical plating techniques (40 per group) were investigated. Condyles were fractured at a defined location from the incisure to the posterior border. After correct anatomical reduction the fractures were plated, using four different techniques. Osteosynthesis materials used were the delta plate, the trapezoid plate, the dynamic compression plate and double mini-plates. Each group was subjected to linear loading in lateral to medial, medial to lateral, anterior to posterior and posterior to anterior directions by a universal mechanical testing machine TIRAtest 2720. Yield load, yield displacement were measured for the different plates. Statistically significant differences were noted between the fixation groups in all four directions. Rigid internal fixation with double mini plates showed the best stability in all directions except posterior to anterior. In this direction, the delta-plate resisted the highest loads. In the three other directions, the delta plate was second best with data similar to double miniplates but lower in magnitude.     

Biomechanical Properties of the Pelvic Floor and its Relation to Pelvic Floor Disorders

Pelvic organ prolapse and stress urinary incontinence remain a clinical challenge as they have unclear pathophysiology and suboptimal treatments. These common pelvic floor disorders (PFD) are characterized by the weakening of the pelvic floor supportive tissues that are directly related to their biomechanical properties. Characterizing the biomechanical properties of the pelvic floor tissues has been the focus of recent studies and researchers are using tools that are not always well understood by clinicians. Therefore, the aim of this review is to provide an overview of the most used methods to test the passive biomechanical properties of the human pelvic floor tissues. We also summarize recent findings from studies looking into the passive properties of the pelvic floor in pelvic floor disorders using the ex vivo tensile test and emerging in vivo techniques. Together, these studies provide valuable quantitative information about the different biomechanical properties of the supportive tissues of the pelvic floor under normal and pathological conditions. Results from ex vivo tests provide valuable data that needs to be correlated to the in vivo data and the clinical manifestations of the symptoms of the PFD. As more research is conducted we will obtain an enhanced understanding of the effect of age, PFD, and treatments on the biomechanical properties of the pelvic floor. This information can contribute to better identify individuals at risk, improve clinical diagnosis, and develop new treatments to advance clinical practice.     

The application of 3D-printed transparent facemask for facial scar management and its biomechanical rationale

Introduction

Deep facial burns leave conspicuous scar to the patients and affect their quality of life. Transparent facemask has been adopted for the prevention and treatment of facial hypertrophic scars for decades. Recently, with the advancement of 3D printing, the transparent facemask could facilitate the fitting of the facial contour. However, the effectiveness of the device and its biomechanical characteristics on pressure management of hypertrophic scar would need more objective evaluation.

The stabilizing potential of anterior, posterior and combined techniques for the reconstruction of a 2-level cervical corpectomy model: biomechanical study and first results of ATPS prototyping

Clinical studies reported frequent failure with anterior instrumented multilevel cervical corpectomies. Hence, posterior augmentation was recommended but necessitates a second approach. Thus, an author group evaluated the feasibility, pull-out characteristics, and accuracy of anterior transpedicular screw (ATPS) fixation. Although first success with clinical application of ATPS has already been reported, no data exist on biomechanical characteristics of an ATPS-plate system enabling transpedicular end-level fixation in advanced instabilities. Therefore, we evaluated biomechanical qualities of an ATPS prototype C4–C7 for reduction of range of motion (ROM) and primary stability in a non-destructive setup among five constructs: anterior plate, posterior all-lateral mass screw construct, posterior construct with lateral mass screws C5 + C6 and end-level fixation using pedicle screws unilaterally or bilaterally, and a 360° construct. 12 human spines C3–T1 were divided into two groups. Four constructs were tested in group 1 and three in group 2; the ATPS prototypes were tested in both groups. Specimens were subjected to flexibility test in a spine motion tester at intact state and after 2-level corpectomy C5–C6 with subsequent reconstruction using a distractable cage and one of the osteosynthesis mentioned above. ROM in flexion–extension, axial rotation, and lateral bending was reported as normalized values. All instrumentations but the anterior plate showed significant reduction of ROM for all directions compared to the intact state. The 360° construct outperformed all others in terms of reducing ROM. While there were no significant differences between the 360° and posterior constructs in flexion–extension and lateral bending, the 360° constructs were significantly more stable in axial rotation. Concerning primary stability of ATPS prototypes, there were no significant differences compared to posterior-only constructs in flexion–extension and axial rotation. The 360° construct showed significant differences to the ATPS prototypes in flexion–extension, while no significant differences existed in axial rotation. But in lateral bending, the ATPS prototype and the anterior plate performed significantly worse than the posterior constructs. ATPS was shown to confer increased primary stability compared to the anterior plate in flexion–extension and axial rotation with the latter yielding significance. We showed that primary stability after 2-level corpectomy reconstruction using ATPS prototypes compared favorably to posterior systems and superior to anterior plates. From the biomechanical point, the 360° instrumentation was shown the most efficient for reconstruction of 2-level corpectomies. Further studies will elucidate whether fatigue testing will enhance the benefit of transpedicular anchorage with posterior constructs and ATPS.