膝关节粘连关节镜下射频汽化消融松解术

目的总结关节镜下射频汽化消融技术在膝关节粘连松解术中的应用体会及短期临床效果。方法2002年1月至2005年6月,对各种原因所致膝关节粘连32例行关节镜下射频汽化消融粘连松解术。依据关节造影所示粘连程度分为3组：A组18例髌上囊粘连,单纯做髌上囊及内外侧沟上方成形。B组8例主要为关节间隙粘连,在做髌上囊及侧沟粘连带清理后加髁问窝清理,加压屈曲膝关节,切断内外侧关节间隙粘连带。C组6例膝关节大部分粘连,进镜操作困难者加做髌骨内外上极小切口,先做髌上囊钝性分离造成腔隙,然后镜下进一步松解。松解配合推拿。射频汽化电极点凝行关节腔内彻底止血。术后不留置引流,第2天开始被动结合主动膝关节加压屈伸功能锻炼。结果A组术前屈曲35°～75°,术后3周115°～125°,平均改善78°；B组术前屈曲40°～60°,术后3周95°～120°,平均改善72°；C组术前屈曲25°～45°,术后3周90°～110°,平均改善64°。术后关节腔内无积血,关节及其周围组织肿胀轻。结论关节镜下射频汽化消融松解膝关节粘连出血少,创伤小,松解效果可靠,可避免以往方法的不利因素,对于髌上囊、侧沟或关节间隙粘连的患者尤为适用。     

Der Einfluß des Druckes in den Coronararterien auf die Druck-Volumen-Beziehung des linken Ventrikels

Summary The influence of coronary perfusion pressure on the pressure-volume relation of the left ventricle was investigated in isolated and arrested cat and dog hearts. The left coronary artery was separately perfused.The duration of the experiment, edema of the myocardium and the inflow through the Thebesian vessels complicate the measurement of the pressure-volume relation.Excluding these factors the experiments prove, that coronary perfusion pressure is a determinant of the pressure-volume relation of the heart. Increasing coronary pressure shifts the relation between pressure and volume upward and to the left (Figs. 3 and 4). increases with increasing coronary perfusion pressure, while the elasticity modulus is not changed (Fig. 5).

     

Adaptation to destabilizing dynamics by means of muscle cocontraction

Adaptive control of wrist mechanics was investigated by means of destabilizing dynamics created by a torque motor. Subjects performed a 20 degrees movement to a 3 degrees target under the constraint that no motion should occur outside of the target zone once 800 ms had elapsed from movement onset. This constraint served as the minimum acceptable level of postural stability. The ability of subjects to modify their muscle activation patterns in order to successfully achieve this stability was investigated by creating three types of destabilizing dynamics with markedly different features: negative stiffness, negative damping, and square-wave vibration. Subjects performed sets of trials with the first type of destabilizing dynamics and were then required to adapt to the second and third. The adaptive response was quantified in terms of the rms electromyographic (EMG) activity recorded during various phases of the task. Surface EMG activity was recorded from three muscles contributing to wrist flexion and three muscles contributing to wrist extension. With negative stiffness, a significant compensatory increase in cocontraction of wrist flexor and extensor muscles was observed for slow movements, but there was little change in the muscle activity for rapid movements. With negative damping, muscle cocontraction was elevated to stabilize rapid movements, declining only gradually after the target was reached. For slow movements, cocontraction occurred only when negative damping was high. The response to square-wave vibration (10 Hz, +/-0.5 Nm), beginning at movement onset, was similar to that of negative damping, in that it resulted in elevated cocontraction. However, because the vibration persisted after the target was reached, there was no subsequent decrease in muscle activity. When the frequency was reduced to 5.5 Hz, but with the same torque impulse, cocontraction increased. This is consistent with greater mechanical instability. In summary, agonist-antagonist cocontraction was adapted to the stability of the task. This generally resulted in less of a change in muscle activity during the movement phase, when the task was performed quickly compared with slowly. On the other hand, the change in muscle activity during stabilization depended more on the nature of the instability than the movement speed.     

Interaction between pre-landing activities and stiffness regulation of the knee joint musculoskeletal system in the drop jump: implications to performance

The purpose of the present study was to investigate the interaction between the pre-landing activities and the stiffness regulation of the knee joint musculoskeletal system and the takeoff speed during a drop jump (DJ). Nine healthy male subjects performed a DJ test from the height of 50 cm. The surface electromyographic (EMG) activity of the vastus lateralis (VL) muscle was recorded to evaluate both the pre-landing and post-landing muscle activation levels. Simultaneous recording of the jumping motion and ground reaction force was performed by a high-speed video camera (100 frames·s^–1), and a force platform was employed to allow joint moment analysis. Joint stiffness was calculated by a linear regression of the knee joint moment/angle relationship. Elasticity of the knee extensor muscle during DJ was estimated by means of a four-element muscle model consisting of a parallel elastic component, a series elastic component (SEC), a viscous damper, and a contractile element. DJ performance correlated positively with the positive peak power of the knee joint (P<0.01) and with the moment of the knee joint at the end of stretch (P<0.01). However, there was no significant relationship between DJ performance and the positive peak power of the ankle joint. The knee joint moment at the end of stretch correlated with the SEC stiffness during the transmission phase from the end of the initial impact to the onset of the concentric action (P<0.01) and with the maximum rate of isometric force development of the knee extensors (P<0.01). Multiple regression analysis showed that the SEC stiffness during the transmission phase of the knee joint can be explained by a combination of the pre-activity of the VL muscle and the knee joint angular velocity at touchdown (F=5.76, P<0.05). These results seem to emphasize the functional significance of the pre-programmed activity for controlling the subsequent stiffness regulation and then contributing to the performance in DJ. Thus, it can be suggested that the centrally pre-programmed activity and the associated elastic behavior of the SEC in the knee extensor muscle in conjunction with the muscle contractile property play a major role in regulating the performance in DJ. Electronic Publication     

Trabecular Shear Stresses Predict <Emphasis Type="Italic">In Vivo</Emphasis> Linear Microcrack Density but not Diffuse Damage in Human Vertebral Cancellous Bone

Linear microcracks and diffuse damage (staining over a broad region) are two types of microscopic damage known to occur in vivo in human vertebral trabecular bone. These damage types might be associated with vertebral failure. Using microcomputed tomography and finite element analysis for specimens of cancellous bone, we estimated the stresses in the trabeculae of human vertebral tissue for inferosuperior loading. Microdamage was quantified histologically. The density of in vivo linear microcracks was, but the diffuse damage area was not, related to the estimates of von Mises stress distribution in the tissue. In vivo linear microcrack density increased with increasing coefficient of variation of the trabecular von Mises stress and with increasing average trabecular von Mises stress generated per superoinferior apparent axial stress. Nonlinear increase in linear crack density, similar to the increase of the coefficient of variation of trabecular shear stresses, with decreasing bone stiffness and bone volume fraction suggests that damage may accumulate rather rapidly in diseases associated with low bone density due to the dramatic increase of shear stresses in the tissue. © 2003 Biomedical Engineering Society. PAC2003: 8719Rr, 8719Xx, 8759Ls, 8759Fm, 8710+e     

Inability to activate muscles maximally during cocontraction and the effect on joint stiffness

In order to determine the maximum joint stiffness that could be produced by cocontraction of wrist flexor and extensor muscles, experiments were conducted in which healthy human subjects stabilized a wrist manipulandum that was made mechanically unstable by using positive position feedback to create a load with the characteristics of a negative spring. To determine a subject's limit of stability, the negative stiffness of the manipulandum was increased by increments until the subject could no longer reliably stabilize the manipulandum in a 1° target window. Static wrist stiffness was measured by applying a 3° rampand-hold displacement of the manipulandum, which stretched the wrist flexor muscles. As the load stiffness was made more and more negative, subjects responded by increasing the level of cocontraction of flexor and extensor muscles to increase the stiffness of the wrist. The stiffness measured at a subject's limit of stability was taken as the maximum stiffness that the subject could achieve by cocontraction of wrist flexor and extensor muscles. In almost all cases, this value was as large or larger than that measured when the subject was asked to cocontract maximally to stiffen the wrist in the absence of any load. Static wrist stiffness was also measured when subjects reciprocally activated flexor or extensor muscles to hold the manipulandum in the target window against a load generated by a stretched spring. We found a strong linear correlation between wrist stiffness and flexor torque over the range of torques used in this study (20–80% maximal voluntary contraction). The maximum stiffness achieved by cocontraction of wrist flexor and extensor muscles was less than 50% of the maximum value predicted from the joint stiffness measured during matched reciprocal activation of flexor and extensor muscles. EMG recorded from either wrist flexor or extensor muscles during maximal cocontraction confirmed that this reduced stiffness was due to lower levels of activation during cocontraction of flexor and extensor muscles than during reciprocal contraction.     

细胞外基质在肝细胞性肝癌发生发展过程中的作用

肝细胞性肝癌（HCC）是我国常见的恶性肿瘤性疾病。近年来微环境对癌组织的影响受到重视,其中细胞外基质（ECM）作为HCC组织的重要微环境成分,在肿瘤发生发展过程中扮演着重要的角色,涉及肿瘤的生长、凋亡、耐药、侵袭、转移等。纤连蛋白（FN）、层粘连蛋白（LN）、透明质酸（HA）、胶原蛋白（COL）以及细胞外基质的硬度在HCC的发生发展过程中所起到的特殊作用。正是由于ECM各蛋白成分在HCC中的特殊作用,若盲目降解或敲除ECM中任意蛋白成分,可能无法达到预期的治疗效果,反而加速HCC的进展。所以需要探索某种特定的方法用于靶向调节ECM中成分,精准控制ECM重塑,从而调控HCC的发生发展。HCC微环境是一个持续变化的动态环境,为了尽可能模拟HCC细胞所处微环境,运用多种ECM蛋白成分而非单一成分联合培养HCC细胞以探究ECM多成分对细胞的共同作用是可行的研究方向。     

Exercise handout and one-on-one hand therapy for management of stiffness after plaster cast immobilization of simple phalangeal and metacarpal fractures in children: A randomized,noninferiority trial

Study DesignThis is a noninferior, single-blind, randomized controlled trial.IntroductionJoint stiffness is common after plaster cast immobilization for simple phalanx and metacarpal fractures in children. The limited literature suggests this joint stiffness in children resolves without one-on-one therapy; however, without robust studies confirming that there is no detrimental effect from withdrawing treatment, many children are still referred.Purpose of the StudyThe purpose of this study was to determine if an educational handout for self-management of stiffness is noninferior to one-on-one hand therapy for achieving full range of motion (ROM).MethodsParticipants were randomly assigned to group one who received the handout or group two who received hand therapy in addition to the handout. The ROM was measured by composite flexion and total active motion (TAM). The noninferiority margin was 10% difference between the two groups in the proportion of participants who achieved full ROM at two weeks after cast removal.ResultsSixty participants in each group completed the study. Group difference for composite flexion was 1.7% (95% CI: −3.9% to 7.2%), demonstrating noninferiority. Group difference for TAM was inconclusive at 8.3% (95% CI: −2.1% to 18.7%). Sensitivity analysis adjusting for participants with full composite flexion at the baseline resulted in the group difference for composite flexion of 3.1% (95% CI: −3.6% to 9.8%), maintaining noninferiority, but group difference for TAM at 10.4% (95% CI: 0.0% to 20.9%), was inconclusive with the handout group significantly worse.ConclusionAn educational handout is noninferior to hand therapy for achieving full ROM in composite flexion but not TAM. This needs to be taken into consideration for changing clinical practise.