The adaptive shortening or tightness of the pectoralis minor muscle (PMm) is one of the potential biomechanical mechanisms associated with altered scapular alignment at rest and scapular motion during arm elevation (scapular dyskinesis) in patients with shoulder complaints. This masterclass briefly reviews the role of the PMm in shoulder movement-related impairments and provides a critical overview of the assessment of PMm tightness and the conventional approaches to increase its resting length and extensibility. A rehabilitation approach focused on PMm stretching and simultaneous optimization of the kinematic chain of arm elevation is also discussed, hoping to improve the management of shoulder movement-related impairments and pain.

Abstract Objective: This study analyzed the effect of ionizing radiation on bone microarchitecture and biomechanical properties in the bone tissue surrounding a dental implant. Methodology: Twenty rabbits received three dental morse taper junction implants: one in the left tibia and two in the right tibia. The animals were randomized into two groups: the nonirradiated group (control group) and the irradiated group, which received 30 Gy in a single dose 2 weeks after the implant procedure. Four weeks after the implant procedure, the animals were sacrificed, and the implant/bone specimens were used for each experiment. The specimens (n=10) of the right tibia were examined by microcomputed tomography to measure the cortical volume (CtV, mm3), cortical thickness (CtTh, mm) and porosity (CtPo, %). The other specimens (n=10) were examined by dynamic indentation to measure the elastic modulus (E, GPa) and Vickers hardness (VHN, N/mm2) in the bone. The specimens of the left tibia (n=10) were subjected to pull-out tests to calculate the failure load (N), displacement (mm) up to the failure point and interface stiffness (N/mm). In the irradiated group, two measurements were performed: close, at 1 mm surrounding the implant surface, and distant, at 2.5 mm from the external limit of the first measurement. Data were analyzed using one-way ANOVA, Tukey’s test and Student’s t-test (α=0.05). Results: The irradiated bone closer to the implant surface had lower elastic modulus (E), Vickers hardness (VHN), Ct.Th, and Ct.V values and a higher Ct.Po value than the bone distant to the implant (P<0.04). The irradiated bone that was distant from the implant surface had lower E, VHN, and Ct.Th values and a higher Ct.Po value than the nonirradiated bone (P<0.04). The nonirradiated bone had higher failure loads, displacements and stiffness values than the irradiated bone (P<0.02). Conclusion: Ionizing radiation in dental implants resulted in negative effects on the microarchitecture and biomechanical properties of bone tissue, mainly near the surface of the implant.

OBJECTIVE: To analyze the results of biomechanical assays of fixation of Pauwels type III femoral neck fracture in synthetic bone, using 7.5mm cannulated screws in inverted triangle formation, in relation to the control group. METHODS: Ten synthetic bones were used, from a domestic brand, divided into two groups: test and control. In the test group, a 70° tilt osteotomy of the femoral neck was fixated using three cannulated screws in inverted triangle formation. The resistance of this fixation and its rotational deviation were analyzed at 5mm displacement (phase 1) and 10mm displacement (phase 2). The control group was tested in its integrity until the fracture of the femoral neck occurred. The Mann-Whitney test was used for group analysis and comparison. RESULTS: The values in the test group in phase 1, in samples 1-5, showed a mean of 579N and SD =77N. Rotational deviations showed a mean of 3.33°, SD = 2.63°. In phase 2, the mean was 696N and SD =106N. The values of the maximum load in the control group had a mean of 1329N and SD=177N. CONCLUSION: The analysis of mechanical strength between the groups determined a statistically significant lower value in the test group. Level of Evidence III, Control Case.

Objective: To analyze statistically results in biomechanical testing of fixation of femoral neck Pauwels type III fractures, on synthetic bone, with dynamic condylar screw (DCS) and control group.Methods: Ten synthetic bones of a national brand were used. Test Group: fixation was performed after osteotomy at 70o tilt using DCS plate with four holes. We analyzed the resistance of this fixation with 5 mm displacement and rotational deviation (Step 1) and with10 mm (Step 2). Control group: the models were tested in their integrity until the femoral neck fracture occurred.Results: The values of the test group in Step 1 showed a mean of 974N and SD = 114N. In Stage 2, we obtained on average 1335N and SD = 98N. The values in the control group were: 1544N, 1110N, 1359N, 1194N, 1437N, respectively. Statistical analysis using the Mann-Whitney test for comparison of the maximum force (N) between the test group and the control, in Step 2, demonstrated that there is no significant difference between the DCS and control plates (p = 0.91).Conclusion: There is no significant difference between the DCS boards and the control group exposed to full resistance. Level of Evidence III, Case Control.

Objective: To measure and compare tibial torsion values as assessed by goniometry and three-dimensional kinematics. In addition, the impact of each one of these measurements on kinematic and kinetic results for normal gait was determined.Methods: Twenty-three healthy and fully ambulatory patients were assessed, 11 women and 12 men, from 20 to 40 years old. Data were collected at a laboratory for the three-dimensional analysis of movement with 10 cameras and two force plates. Tibial torsion measurements were obtained using goniometry and three-dimensional kinematics based on the Plug-in Gait model. Afterwards, both procedures were compared, and the impact of each result was assessed on the kinematic and kinetic modeling of the knee and ankle.Results: Pearson's linear correlation coefficient (r=0,504) showed a moderate correlation between the three-dimensional kinematics and goniometry, and between the changes in the measurements. Regarding the processed kinematic and kinetic results for every torsion position, no significant differences were noticed among any of the studied variables (p>0.05).Conclusion: Although statistical correlation among tibial torsion angles by goniometry and three-dimensional kinematic were moderate, kinematic and kinetic analysis of the joints did not reveal any significant changes. Level of Evidence I, Diagnostic Studies - Investigating a Diagnostic Test.

The aim in the present study was to analyze the stress in the external hexagon implant (EH) in a situation of parafunction on three-unit implant-supported prostheses with and without the use of the acrylic occlusal device (AOD) using three-dimensional (3D) finite element analysis (FEA). Eight 3D models referring to the posterior maxilla with three EH supporting single and or splinted screwed metal-ceramic restoration and use of the AOD. AOD was modeled with a thickness of 2 mm. EHs were analyzed using von Mises criteria in the ANSYS 19.2 program. AOD showed to be effective in reducing stress in the EH. However, the use of the AOD was not effective enough to suggest the non-splinting of EH dental implant. The association of splinting and the use of an AOD in the posterior region of the maxilla may be an effective way to decrease the stress in the EH implant in a situation of parafunction.

Objective: To compare the pedobarographic findings of plantar pressure distribution in individuals with typical diabetic neuropathy with non-diabetic individuals. Methods: 25 patients with typical diabetic neuropathy were randomly selected and another 25 non-diabetic patients were selected electively. After undergoing clinical examination according to the report and recommendations of the San Antonio Conference on Diabetic Neuropathy, glycated hemoglobin (HbA1c) and static podobarography tests were performed to identify pressure points in the feet and distribution of plantar pressure. Results: The mean age of 62.24 (± 9.01) years, mean body mass index (BMI) of 29.69 (± 5.9) Kg / m² and mean HbA1c of 8.9 (± 3.29% of non-diabetic patients, mean age was 61.04 (± 9.69). The mean hallucin pressure in the diabetic group was 111.16 (± 64.25) kPa, in the non-diabetic group was 78.91 (± 4.43) Kg / m² and HbA1c was 5.3 (± 0.24) ± 38.48) kPa and the comparison showed ap = 0.015. Conclusion: An increase in pressure was found in the hallux region of diabetic patients when compared to non-diabetic patients.

The aim of this study is to evaluate by finite element analysis different techniques of totally edentulous maxilla rehabilitation, considering implants, bone tissue, metallic infra-structure, and prosthetic abutments characteristics, by means of a three-dimensional model. Stress distribution on bone tissue, implants, and abutments was analyzed with four configurations (six implants axially installed, all-on-four technique, M-4 technique, and four conventional implants with two zygomatic implants). Greater tension on bone tissue were found around distal implants, in all treatment groups, but not exceeding resistance limits of cortical bone. Von Mises stress was higher on the distal region of distal implants of all-on-four and M-4 techniques. Higher stress concentration was seen on angled abutments of zygomatic implants. The highest values of minimal compression stresses were concentrated on peri implant-bone tissue, especially in the model of All-on-4.  Therefore, the present finite element analysis revealed that the four configurations of treatment (six implants axially installed, all-on-four technique, M-4 technique, and four conventional implants with two zygomatic implants) for the totally edentulous maxilla are feasible and safe, from a biomechanical point of view.

ABSTRACT BACKGROUND AND OBJECTIVES: Walking is described as one of the abilities most affected by chronic low back pain. This study aimed to determine if chronic nonspecific low back pain and walking speed affect the spatiotemporal parameters (stride length, swing time, contact time, stride time, stride frequency and walking ratio) and the coefficients of variation of stride length and contact time. METHODS: Ten participants with chronic nonspecific low back pain (low back pain - LG) and ten healthy participants in the control group (CG) walked on the treadmill at preferred self-selected speed, slower and faster than the preferred speed. Spatiotemporal parameters and coefficients of variation were determined by kinematic analysis. Main effects (group and speed) and their interactions were tested using generalized estimating equations method. RESULTS: Our results showed that there were no significant differences between groups or significant interaction between group and speed factors. There was a speed effect. Stride frequency and length increased while contact and stride time decreased as the speed increased. The walking ratio (stride length/stride frequency) was relatively consistent across speeds (~1.6 m·stride-1.s) without statistical differences. The coefficients of variation were below 5%. CONCLUSION: The chronic nonspecific low back pain did not affect the gait spatiotemporal profile, at least for those patients classified as chronic nonspecific low back pain according to the signs and symptoms criteria. Although the preferred speed has affected the spatiotemporal parameters, both groups patients were able to adjust their kinematic parameters to each task demand.