Activation of the hypoxia-inducible factor-1 in overloaded temporomandibular joint, and induction of osteoclastogenesis

Vascular endothelial growth factor (Vegf) was previously shown to be expressed specifically in the condylar cartilage of temporomandibular joint-osteoarthritis (TMJ-OA) model rats. Here we demonstrate for the first time that hypoxia-inducible factor-1α (Hif-1α) is activated in mature chondrocytes of temporomandibular joint-osteoarthritis (TMJ-OA) model rat by mechanical overload, and that activated Hif-1 in chondrocytes can induce osteoclastogenesis via repression of osteoprotegerin (Opg) expression.In rat TMJs, degeneration of the condylar cartilage became prominent in proportion to the duration of overloading. Hif-1α expression was observed specifically in mature and hypertrophic chondrocytes, and Hif-1α-positivity, level of Vegf expression, and tartrate-resistant acid phosphatase (TRAP)-positive cell numbers all increased in the same manner. When ATDC5 cells induced differentiation by insulin were cultured under hypoxia, Hif-1α induction was observed in mature stage, but not in immature stage. Inductions of Hif-1-target genes showed a similar expression pattern. In addition, expression of Opg decreased in hypoxia, and Hif-1α played a role, in part, in its regulation.     

Effect of surface roughness on squeeze film poroelastic bearings with special reference to synovial joints

A simplified mathematical model has been developed for understanding the combined effects of surface roughness and couple stresses on lubrication aspects of synovial joints. The modified Reynolds equation which incorporates the elastic as well as randomized surface roughness structure of cartilage with couple-stress fluid as lubricant is derived. The mean pressure, load carrying capacity and time of approach as functions of film thickness during normal articulation of joints are obtained by using Christensen stochastic theory with the assumption that the roughness asperity heights are to be small compared to the film thickness. The effects of surface roughness and elasticity are considerably pronounced for the poroelastic bearings with couple-stress fluid as lubricant compared with classical case.     

Bone density spatial patterns in the distal radius reflect habitual hand postures adopted by quadrupedal primates

Primates adopt diverse hand postures during terrestrial and above-branch quadrupedal locomotion--knuckle-walking, digitigrady, and palmigrady--that incorporate varying degrees of wrist dorsiflexion (i.e., extension). Although relationships between hand postures, wrist joint range of motion, and the external properties of wrist bones (e.g., surface morphology) have been examined, the relationship between hand postures and the internal properties of wrist bones (e.g., bone density) remains largely unexplored. Because articular joint surfaces transmit mechanical loads between conjoining limb bones, measures of density (e.g., magnitudes and patterns) in the subchondral cortical plate of bone of the distal radius can be used to evaluate load regimes experienced by the wrist joint in different hand postures. We assessed apparent (i.e. optical) density patterns in several extant catarrhine primate taxa partitioned into different hand posture groups: knuckle-walking apes, digitigrade monkeys, and palmigrade monkeys. Computed tomography osteoabsorptiometry (CT-OAM) was used to construct maximum intensity projection (MIP) maps of apparent densities. High apparent density areas were characterized relative to a dorsal-volar reference plane and compared across hand posture groups. All groups had large percentage areas of high apparent density in the dorsal region of the distal radial articular surface. Only knuckle-walking apes, however, had a large percentage area of high apparent density in the volar region of the distal radial articular surface. These patterns are consistent with radiocarpal articulations in specific hand postures as evidenced by available radiographic data and suggest that the different habitual hand postures adopted by monkeys and African apes during quadrupedal locomotion have different stereotypic loading patterns. This has implications for understanding the functional morphology and evolution of knuckle-walking and digitigrade hand postures in primates.     

Anterior hip joint force increases with hip extension, decreased gluteal force, or decreased iliopsoas force

Abnormal or excessive force on the anterior hip joint may cause anterior hip pain, subtle hip instability and a tear of the acetabular labrum. We propose that both the pattern of muscle force and hip joint position can affect the magnitude of anterior joint force and thus possibly lead to excessive force and injury. The purpose of this study was to determine the effect of hip joint position and of weakness of the gluteal and iliopsoas muscles on anterior hip joint force. We used a musculoskeletal model to estimate hip joint forces during simulated prone hip extension and supine hip flexion under four different muscle force conditions and across a range of hip extension and flexion positions. Weakness of specified muscles was simulated by decreasing the modeled maximum force value for the gluteal muscles during hip extension and the iliopsoas muscle during hip flexion. We found that decreased force contribution from the gluteal muscles during hip extension and the iliopsoas muscle during hip flexion resulted in an increase in the anterior hip joint force. The anterior hip joint force was greater when the hip was in extension than when the hip was in flexion. Further studies are warranted to determine if increased utilization of the gluteal muscles during hip extension and of the iliopsoas muscle during hip flexion, and avoidance of hip extension beyond neutral would be beneficial for people with anterior hip pain, subtle hip instability, or an anterior acetabular labral tear.     

陈旧性肘关节脱位并骨性强直的治疗研究

目的研究陈旧性肘关节脱位并骨性强直的手术治疗和康复方法。方法采用MeConnell肘后皮肤切口结合Campbell后侧入路显露肘关节及肱三头肌腱延长,肘关节松解复位术,并早期进行康复训练。结果全部患者的伤口均一期愈合,无明显异位骨再生,活动无疼痛,无并发症,短期随访功能恢复良好。结论后入路松解复位术适于陈旧性肘关节后脱位并伸肘位骨性强直未超过12周的病例,结合康复治疗能有效减轻组织反应,促进功能恢复。     

关节镜下多种移植物联合重建膝关节前、后交叉韧带

目的：评估关节镜下膝关节前交叉韧带（ACL）与后交叉韧带（PCL）同时重建的技术和临床效果。方法：自2003年6月～2009年10月,27例病人（28膝）经MRJ检查及关节镜检查证实ACL和PCL均断裂,其中9膝伴内侧副韧带损伤（MCL）,8膝伴后外侧角损伤（PLC）,5膝伴内侧半月板破裂,4膝伴外侧半月板损伤。27例患者于伤后3～10周在关节镜下行膝关节前、后交叉韧带联合重建。结果：本组术后早期均未发生严重并发症。术后随访12-88个月,平均（42．67±3．34）个月,Lysholm膝关节功能评分为78-93分,平均（86．67±5．21）分。国际膝关节文件编制委员会（mDC）综合评定由术前显著异常（D级）28膝,改进为随访时正常（A级）9膝、接近正常（B级）16膝、异常（C级）3膝。结论：关节镜下膝关节前交叉韧带（ACL）与后交叉韧带（PCL）同时重建创伤小、手术操作精细,术后膝关节功能恢复满意。     

关节镜下多种移植物联合重建膝关节前、后交叉韧带

目的:评估关节镜下膝关节前交叉韧带(ACL)与后交叉韧带(PCL)同时重建的技术和临床效果。方法:自2003年6月～2009年10月,27例病人(28膝)经MRI检查及关节镜检查证实ACL和PCL均断裂,其中9膝伴内侧副韧带损伤(MCL),8膝伴后外侧角损伤(PLC),5膝伴内侧半月板破裂,4膝伴外侧半月板损伤。27例患者于伤后3～10周在关节镜下行膝关节前、后交叉韧带联合重建。结果:本组术后早期均未发生严重并发症。术后随访12～88个月,平均(42.67±3.34)个月,Lysholm膝关节功能评分为78～93分,平均(86.67±5.21)分。国际膝关节文件编制委员会(IKDC)综合评定由术前显著异常(D级)28膝,改进为随访时正常(A级)9膝、接近正常(B级)16膝、异常(C级)3膝。结论:关节镜下膝关节前交叉韧带(ACL)与后交叉韧带(PCL)同时重建创伤小、手术操作精细,术后膝关节功能恢复满意。     

咬合运动与注射醋酸泼尼松龙治疗滑膜炎的疗效比较

目的:比较咬合运动和关节下腔注射醋酸泼尼松龙治疗颞下颌关节滑膜炎的临床效果。方法:选择牙列完整、无第三磨牙阻生、符合颞下颌关节滑膜炎诊断标准的120例患者,随机分为实验组和对照组,每组60例。实验组行咬合运动,每次3-4个循环,每日3-4次,治疗周期为12个月;对照组给予醋酸泼尼松龙0.0125g+0.5ml2%利多卡因关节下腔注射一次,比较两种方法的治疗效果。结果:实验组的60例患者均在治疗后1-2w疼痛消失,追踪3-12个月无复发。对照组的60例患者,2个周后有18例无效,无效率为30%,两组比较其结果有显著性差异(P<0.001);3个月后有22例无效,无效率为36.67%,两组比较其结果有显著性差异(P<0.001)。结论:咬合运动组的治疗效果显著高于醋酸泼尼松龙注射组,咬合运动能有效的治疗滑膜炎并减少患者的治疗痛苦。     

The predatory behaviour of the thylacine: Tasmanian tiger or marsupial wolf?

The extinct thylacine (Thylacinus cynocephalus) and the extant grey wolf (Canis lupus) are textbook examples of convergence between marsupials and placentals. Craniodental studies confirm the thylacine's carnivorous diet, but little attention has been paid to its postcranial skeleton, which would confirm or refute rare eyewitness reports of a more ambushing predatory mode than the pack-hunting pursuit mode of wolves and other large canids. Here we show that thylacines had the elbow morphology typical of an ambush predator, and propose that the 'Tasmanian tiger' vernacular name might be more apt than the 'marsupial wolf'. The 'niche overlap hypothesis' with dingoes (Canis lupus dingo) as a main cause of thylacine extinction in mainland Australia is discussed in the light of this new information.