Postural coordination patterns associated with the swinging frequency of arms

Voluntary arm movements frequently perturb body equilibrium in an upright posture. The motions of leg joints need to be coordinated according to the properties of voluntary arm movements in order to maintain body equilibrium, and this may cause a change in postural pattern. The purpose of this study was to determine whether the kinematic pattern generation of upright posture is influenced by a change in the swinging frequency of arm movements and whether the pattern generation is correlated with a change in joint torque about the shoulder joint. Four male subjects in an upright posture were instructed to swing their arms at seven different frequencies, determined by the maximum swinging frequency of each subject (35%max, 40~60%max, 65%max). Segment rotations around the shoulder, hip, and ankle joints were analyzed at kinematic and kinetic levels. The results of kinematic analysis indicated that tight coupling between motions of the shoulder and hip joints was generated in lower-frequency trials (under 40–45%max), whereas tight coupling between motions of the shoulder and ankle joints was generated in higher frequency trials (more than 40–45%max). Furthermore, the results of kinetic analysis revealed that changes in the joint torque patterns about the shoulder and hip joints occurred in trials at 40–45%max. The mean value of 40–45%max was close to the eigenfrequency of each subject's arm. We concluded that (1) postural patterns associated with a gradual change in the swinging frequency of the arms can be divided into two coordination modes (a hip-shoulder in-phase mode and an ankle-shoulder in-phase mode), and (2) these two patterns may be divided by the eigenfrequency of the arm. Electronic Publication     

Differential effect of knee extension isometric training on the different muscles of the quadriceps femoris in humans

This study determined the effects of a short period of knee isometric training on the quadriceps muscles accessible to surface electromyography (EMG). For this purpose, a training (n=9) and a control (n=7) group were tested on five identical occasions at 1 week intervals during 4 weeks. The training group exercised three times a week by making isometric knee extensions at 80% of the maximal voluntary contraction (MVC). During the test sessions, maximal and submaximal torque and associated activations of the rectus femoris (RF), vastus lateralis (VL) and vastus medialis (VM) muscles were analysed. As a result of training, differences between MVC values of the two groups were highly significant (P < 0.001), whereas only RF-EMG showed significant differences (P < 0.05). The VL and VM did not present any significant changes in maximal activation. The EMG–torque relationships were analysed individually before and after the training period. For the control subjects, EMG–torque relationships did not present significant changes while for the training group, these relationships showed a significant increase in RF, VL, and VM maximal activation in 6, 6 and 4 subjects, respectively, and a significant decrease in 1, 2 and 5 subjects, respectively. In almost all cases, a significant downward shift of the relationship was observed. This study confirmed that the parts of the quadriceps muscle tested present different adaptation capacities and demonstrate inter-individual variability in the strategies used to enhance muscle strength. In conclusion, to analyse the neural effects resulting from training in a large and compartmentalized muscle like the quadriceps femoris, it is desirable to take into account each muscle independently. Moreover, we suggest that overall results obtained from the experiment population should be completed by an analysis on individuals. Accepted: 1 September 2000     

Commonalities and differences in control of various drawing movements

Characteristics of control at the shoulder and elbow during nine types of drawing movements were studied in the present work. The task was to repetitively track a template, depicted on a horizontal table, with the index finger at a cyclic frequency of 1.5 Hz. The templates were a circle, four ovals and four lines of different orientations. The wrist was immobilized and the movement consisted of rotations at the shoulder and elbow joints. The studied movements varied in a wide range with respect to the amplitude of elbow and shoulder movements and relative phase between them. Kinetic analysis included analysis of torque signs, impulses, and timing. It demonstrated that the role of muscle torque in movement production was different at the two joints. During eight out of the nine movement types, the muscle torque at the shoulder accelerated and decelerated this joint and almost completely coped with the influence of the interactive torque arising from elbow motion. Conversely, interactive torque generated by shoulder motion played a dominant role in elbow acceleration and deceleration, whereas muscle torque at the elbow adjusted passive elbow movement to the various template shapes. EMG data were in agreement with the conclusions made from the kinetic analysis. Collectively, these data support the hypothesis that the two joints have different functions in movement production. The shoulder creates a foundation for motion of the entire arm through the interactive torque, and the elbow serves as a fine-tuner of the end-point movement. Control of the shoulder was similar across the eight movement types and the differences in the end-point path were provided by variations in elbow control. The two joints exchanged roles during one movement type, namely, drawing the line tilted right. During this movement, the elbow musculature generated motion at this joint and the shoulder musculature counteracted mechanical influence of this motion on the shoulder position. The findings suggest that during drawing movements, the control strategy exploits intersegmental dynamics of the shoulder-elbow mechanical linkage.     

游离下鼻甲粘膜瓣修复鼻中隔术中穿孔

为２１７ 例鼻中隔偏曲患者行鼻中隔偏曲矫正术,９ 例术中出现鼻中隔粘骨膜对位性穿孔,经及时用游离下鼻甲粘膜瓣修复,其修复要点是（１）继续分离中隔穿孔周围粘骨膜,去除穿孔周围的偏曲骨质,以完成中隔矫正术,并扩大放置鼻甲粘膜瓣的空间;（２）取下鼻甲粘膜瓣较正常的部分,要略大于中隔穿孔的大创孔面积,光滑粘膜面可修整使之较为粗糙,以利粘膜瓣生长。８ 例修复成功,仅１ 例发生术后中隔穿孔。     

前牙外科正畸（附8例分析）

目的：本文是讲座牙外科正畸术在前牙中应用效果及并发症的防治,方法：采用不翻粘骨膜瓣的牙－骨块凿开移位术,结果与结论：本文认为对单个或少数前牙排列不齐的牙,采用此方法见效快,时间短。     

Histological,histomorphometrical, and radiological evaluation of an experimental implant design with a high insertion torque

Objectives: The aim of this study was to compare bone behaviour around an experimental implant design with a high insertion torque with the Astra‐Tech^© implant (control). Materials and methods: In ten 18‐month‐old male minipigs, the last premolars and first molars were extracted to provide space for two implants in each quadrant. A first set of 40 implants were placed 3 months after the extraction and 40 additional implants were installed another 2 months later. The animals were sacrificed 3 months after the first implant installation so that half of the implants had healed for 1 month and the other half for 3 months. Radiological evaluation was performed at baseline, 1 month, 2 months, and 3 months after implant installation. Bone defect depth and area, bone level changes, bone‐to‐implant contact density, and peri‐implant bone fraction were measured histomorphometrically. Results: Radiological analyses revealed a significantly higher bone loss around the experimental implants. Histomorphometric analyses confirmed significantly more bone loss, larger marginal bone defects, and a lower overall peri‐implant bone fraction around the experimental implants. Conclusion: The experimental implant design caused significantly more peri‐implant bone loss compared with the control implant. As strain gauge measurements indicate excessive marginal strains around the experimental implants, osseocompression might have played a role in the observed marginal bone loss. To cite this article:
Duyck J, Corpas L, Vermeiren S, Ogawa T, Quirynen M, Vandamme K, Jacobs R, Naert I. Histological, histomorphometrical, and radiological evaluation of an experimental implant design with a high insertion torque.
Clin. Oral Impl. Res. 21 , 2010; 877–884.     

Influence of lateral pressure to the implant bed on osseointegration: an experimental study in dogs

Aim: To study osseointegration and bone‐level changes at implants installed using either a standard or a reduced diameter bur for implant bed preparation. Material and methods: In six Labrador dogs, the first and second premolars were extracted bilaterally. Subsequently, mesial roots of the first molars were endodontically treated and distal roots, including the corresponding part of the crown, were extracted. After 3 months of healing, flaps were elevated and recipient sites were prepared in all experimental sites. The control site was prepared using a standard procedure, while the test site was prepared using a drill with a 0.2 mm reduced diameter than the standard one used in the contra‐lateral side. After 4 months of healing, the animals were euthanized and biopsies were obtained for histological processing and evaluation. Results: With the exception of one implant that was lost, all implants were integrated in mineralized bone. The alveolar crest underwent resorption at control as well as at test sites (buccal aspect ～1 mm). The most coronal contact of bone‐to‐implant was located between 1.2 and 1.6 mm at the test and between 1.3 and 1.7 mm at the control sites. Bone‐to‐implant contact percentage was between 49% and 67%. No statistically significant differences were found for any of the outcome variables. Conclusions: After 4 months of healing, lateral pressure to the implant bed as reflected by higher insertion torques (36 vs. 15 N cm in the premolar and 19 vs. 7 N cm in the molar regions) did not affect the bone‐to‐implant contact. To cite this article:
Pantani F, Botticelli D, Garcia IR Jr., Salata LA, Borges GJ, Lang NP. Influence of lateral pressure to the implant bed on osseointegration: an experimental study in dogs.
Clin. Oral Impl. Res. 21 , 2010; 1264–1270.
doi: 10.1111/j.1600‐0501.2009.01941.x     

Surface-modified zirconia implants: tissue response in rabbits

Aim: To evaluate the bone tissue response to zirconia implants with three different surface modifications in comparison with the oxidized titanium surface with the goal to optimize osseointegration in terms of strength and speed.
Materials and methods: A total of 18 rabbits with 143 implants were used. One hundred and twenty-three were threaded zirconia ceramic implants with three different surface topographies and 20 modified titanium oxide implants were controls. Each rabbit received eight implants and sacrificed after 3 weeks. The removal torque test (RTQ) and histology were performed.
Results: Sixteen out of 18 rabbits completed the study with a total of 110 implants. No statistical significance was observed between the chemical modification implants compared with the topographically modified zirconia implant in terms of interfacial shear strength proven by the RTQ applied. No statistical significance was also observed in the bone-to-implant contact between the zirconia implants and the control oxidized implants.
Conclusions: The findings suggest that additional specific chemical modifications of the topographically modified zirconia implants do not seem to enhance the bone-to-implant contact and appear not to increase the interfacial shear strength.     

Influence of Different Tightening Forces Before Laser Welding to the Implant/Framework Fit

Purpose: The aim of the present study was to evaluate the influence of abutment screw tightening force before laser welding procedures on the vertical fit of metal frameworks over four implants.
Materials and Methods: To construct the frameworks, prefabricated titanium abutments and cylindrical titanium bars were joined by laser welding to compose three groups: group of manual torque (GMT), GT10 and GT20. Before welding, manual torque simulating routine laboratory procedure was applied to GTM. In GT10 and GT20, the abutment screws received 10 and 20 Ncm torque, respectively. After welding, the implant/framework interfaces were assessed by optical comparator microscope using two methods. First, the single screw test (SST) was used, in which the interfaces of the screwed and non-screwed abutments were assessed, considering only the abutments at the framework extremities. Second, the interfaces of all the abutments were evaluated when they were screwed.
Results: In the SST, intergroup analysis (Kruskal Wallis) showed no significant difference among the three conditions of tightening force; that is, the different tightening force before welding did not guarantee smaller distortions. Intragroup analysis (Wilcoxon) showed that for all groups, the interfaces of the non-screwed abutments were statistically greater than the interfaces of the screwed abutments, evidencing distortions in all the frameworks. ANOVA was applied for the comparison of interfaces when all the abutments were screwed and showed no significant difference among the groups.
Conclusions: Under the conditions of this study, pre-welding tightness on abutment screws did not influence the vertical fit of implant-supported metal frameworks.