The significance of the supratrochlear aperture (STA) in elbow range of motion: an anatomical study

Assessment of the range of motion at a joint is among the methods employed by orthopedic surgeons and physiotherapists to determine courses of therapy and joint recovery. Females tend to have a greater range of motion at the elbow joint than males. In the present case–control study, the elbow extension angle was compared between males and females with and without the supratrochlear aperture. A total of 453 dry humeri and their corresponding ulnae were included in the study, and elbow extension angle was measured using a goniometer. The average extension angle in this sample was 173°, and it was significantly greater when the STA was present (\(\bar{X}\) = 175.4°) than when it was absent (\(\bar{X}\) = 171°). It was greater in females (\(\bar{X}\) = 174.5°) than in males (\(\bar{X}\) = 171.3°) irrespective of STA status, and was greater on the left in both sexes. Hyperextension characterized 13 % of the sample, whereas the majority (76 %) showed hypoextension and only a few (11 %) exhibited normal extension. Trochlear notch depth and olecranon–coronoid distance would found to be useful for predicting the presence of the supratrochlear aperture, while the transverse and vertical diameters of the supratrochlear aperture were found to be the most useful parameters when predicting the degree of extension. The functional benefits of hyperextension at the elbow joint are not fully understood. However, these results are important to orthopedic surgeons and physiotherapists as they permit a greater understanding of normal elbow range of motion in the South African population.     

应用动态双平面成像技术研究在体肘关节主动屈伸运动特征

目的 探讨健康肘关节屈伸运动时关节的相对位移和旋转角度变化,为肘关节不稳以及严重肘关节损伤的治疗提供参考。方法 选取10名健康并且无上肢外伤史的受试者。应用动态双平面X线透视成像系统,测量右侧肘关节从旋后最大伸直位至旋后最大屈曲位运动过程中,肱桡与肱尺关节6自由度运动学数据。使用相关性分析评价肘关节不同自由度运动的耦合度。结果 从最大伸直位到最大屈曲位,肱尺关节外翻角从15.2°±3.1°降低到5.3°±2.3°,肱桡关节外翻角从19.7°±4.2°减小到8.2°±2.4°, 肱尺与肱桡关节外翻角与屈曲角呈线性相关;肱尺关节内外旋角先内旋后外旋,呈二次非线性相关,在屈曲110°时达到最大内旋值（4.0°±4.9°）,后达到最大外旋值（5.1°±4.2°）;肱桡关节一直呈内旋增大变化,从内旋3.2°±16.0°增加到内旋27.2°±18.0°。结论 在正常肘关节屈伸过程中,肱尺关节存在外翻角线性减小、内外旋角先内旋后外旋的非线性变化,肱桡关节存在外翻角线性减小、内旋角线性增大的变化。在屈伸过程中,肘关节并非单纯铰链关节,并且肱尺、肱桡关节存在运动学差异。临床上治疗复杂肘关节损伤、肘关节不稳以及肘关节置换手术时,应考虑关节间不同运动特征,以提高术后临床效果。     

Physiological in vitro sacroiliac joint motion: a study on three‐dimensional posterior pelvic ring kinematics

The sacroiliac joint (SIJ) is a well‐known source of low back and pelvic pain, of increasing interest for both conservative and surgical treatment. Alterations in the kinematics of the pelvis have been hypothesized as a major cause of SIJ‐related pain. However, definitions of both the range and the extent of physiological movement are controversial, and there are no clear baseline data for pathological alterations. The present study combined a novel biomechanical setup allowing for physiological motion of the lumbosacral transition and pelvis without restricting the SIJ movement in vitro, combined with optical image correlation. Six fresh human pelvises (81 ± 10 years, three females, three males) were tested, with bodyweight‐adapted loading applied to the fifth lumbar vertebra and both acetabula. Deformation at the lumbopelvises was determined computationally from three‐dimensional image correlation data. Sacroiliac joint motion under the loading of 100% bodyweight primarily consisted of a z‐axis rotation (0.16°) and an inferior translation of the sacrum relative to the ilium (0.32 mm). Sacroiliac joint flexion‐extension rotations were minute (< 0.02°). Corresponding movements of the SIJ were found at the lumbosacral transition, with an anterior translation of L5 relative to the sacrum of ?0.97 mm and an inferior translation of 0.11 mm, respectively. Moreover, a flexion of 1.82° was observed at the lumbosacral transition. Within the innominate bone and at the pubic symphysis, small complementary rotations were seen around a vertical axis, accounting for ?0.10° and 0.11°, respectively. Other motions were minute and accompanied by large interindividual variation. The present study provides evidence of different SIJ motions than reported previously when exerted by physiological loading. Sacroiliac joint kinematics were in the sub‐degree and sub‐millimeter range, in line with previous in vivo and in vitro findings, largely limited to the sagittal rotation and an inferior translation of the sacrum relative to the ilium. This given physiological loading scenario underlines the relevance of the lumbosacral transition when considering the overall motion of the lumbopelvis, and how relatively little the other segments contribute to overall motion.     

Intraoperative assessment of midflexion laxity in total knee prosthesis

BackgroundSoft-tissue balancing of the knee is fundamental to the success of a total knee arthroplasty (TKA). In posterior-stabilized TKA, there is no stabilizer of the anterior–posterior translation in the midflexion range in which the cam-post mechanism does not engage yet. Therefore, instability in the midflexion range is suspected to occur in posterior-stabilized TKA. The purpose of this study was to measure the joint gap throughout a full range of motion and to analyze the joint gap laxity in the midflexion range after implantation of a mobile-bearing posterior-stabilized total knee prosthesis.MethodsJoint gap kinematics in 259 knees with varus osteoarthritis were measured during TKAs using a tensor device with the same shape of a total knee prosthesis of the same design was used. After the implantation of a mobile-bearing posterior-stabilized prosthesis and the reduction of the patellofemoral joint, the joint gap was measured at 0°, 30°, 60°, 90°, 120°, and 145° of flexion.ResultsThe center size of the joint gap was tight in extension and deep flexion and loose at midflexion ranges, especially at 30° of flexion (p < 0.001). The symmetry of the joint gap was varus at 0° and 145° of flexion (p < 0.001).ConclusionsOur results showed the joint gap laxity in the midflexion range after the implantation of a mobile-bearing posterior-stabilized prosthesis. Our new tensor device, which can attach the polyethylene insert trial, will provide the important information about the joint gap kinematics after implantation of total knee prostheses.Level of evidenceIV.     

Successive motor nerve blocks to identify the muscles causing a spasticity pattern: example of the arm flexion pattern

Botulinum Toxin A has been the main treatment for spasticity since the beginning of the 1990s. Surprisingly, there is still no consensus regarding injection parameters or, importantly, how to determine which muscles to target to improve specific functions. The aim of this study was to develop a systematic approach to determine this, using the example of the arm flexion pattern. We first determined anatomical landmarks for selective motor block of the brachialis nerve, using 20 forearms from 10 fresh cadavers in Ecole Européenne de Chirurgie and a university‐based dissection centre, Paris, France. We then carried out selective blocks of the motor nerves to the brachialis, brachioradialis and biceps brachii in patients with stroke with an arm flexion pattern, in a University Rehabilitation Hospital, Garches, France. We measured: the resting angle of the elbow angle in standing (manual goniometer), active and passive range of extension, and spasticity using the Held and Tardieu and the Modified Ashworth scales. Range of passive elbow extension was also measured with the shoulder in 90° of flexion. The resting angle of the elbow in standing decreased by 35.0° (from 87.6 ± 23.7 to 52.6 ± 24.2°) with inhibition of brachialis, by a further 3.9° (from 52.6 ± 24.2 to 48.7 ± 23.7°) with inhibition of brachioradialis and a further 14.5° (from 48.7 ± 23.7to 34.2 ± 20.7°) with inhibition of biceps brachii. These results were consistent with the clinical evaluation of passive elbow range of motion with the shoulder at 90°. Sequential blocking of the nerves to the three main elbow flexors revealed that the muscle that limited elbow extension the most, was brachialis. This muscle should be the main target to improve the arm flexion pattern. These results show that it is important not simply to inject the most superficial or powerful muscles to treat a spastic deformity. A comprehensive assessment is required. The strategy proposed in this paper should increase the effectiveness of botulinum toxin injections by ensuring that the relevant muscles are targeted.     

Investigating canine elbow joint stabilisation through mechanical constraints of the deep fascia and other soft tissues

The objective of this research was to investigate how the range of flexion and extension of the canine elbow joint is constrained by the mechanical connections and attachments of soft tissue structures. The skin, a section of deep fascia and several muscles from both forelimbs from six adult greyhounds and seven other breeds were sequentially transected or removed, over 13 steps. During each step, repeated measurements of elbow flexion and extension were recorded using a goniometer. Only marginally significant changes to the range of flexion occurred in any of the 13 steps or overall for the greyhounds. Clearly significant changes to extension occurred in several dissection steps. Removing the skin resulted in a significant increase in elbow extension of 1.7° ± 0.3 (P < 0.001) in the greyhounds and 1.6° ± 0.3 (P < 0.001) in the other breeds. Severing the deep fascia from the humerus and its connections across the elbow joint resulted in the largest significant change in elbow extension of 9.9° ± 0.3 (P < 0.001) in the greyhounds and 6.9° ± 0.7 (P < 0.001) in the other breeds. Transecting the biceps brachii m. close to the elbow resulted in an increase of 2.8° ± 0.3 (P < 0.001) in the greyhounds but a non‐significant change in the other breeds. Transecting the extensor carpi radialis m. from its origin resulted in an increase of 5.5° ± 0.4 (P < 0.001) in the greyhounds and 3.9° ± 0.7 (P < 0.001) in the other breeds. These results suggest that the collagenous framework and attachments of the skin, deep fascia, and extensor carpi radialis m., play a significant role in the function of the canine elbow by restricting it from overextension and hence stabilising it during periods of loading, in a variety of different canine breeds, and that these structures are functionally integrated into the way the forelimb supports the bodyweight separately from any involvement of muscle tone or muscle movements. Observations on the anatomical connections of the deep fascia between the cranial distal humerus and the antebrachial fascia highlighted its probable importance in relating movements between the shoulder and the carpus.     

解剖型锁定钢板联合Lost K-wire技术治疗Schatzker B型尺骨鹰嘴骨折的近期临床疗效观察

目的 观察解剖型锁定钢板联合Lost K-wire技术治疗Schatzker B型尺骨鹰嘴骨折的近期临床疗效。方法 对2016年6月至2018年6月在本院骨科行手术治疗的13例Schatzker B型尺骨鹰嘴骨折患者的临床资料进行回顾性分析。其中,男5例,女8例;年龄24～56岁,平均36.3岁;摔伤10例,车祸伤3例。均采用Lost K-wire技术结合解剖型锁定钢板治疗。结果 13例患者均获随访12个月,末次随访时肘关节屈伸活动范围105°～145°,平均(124.2±13.2)°;旋转活动范围100°～155°,平均(130.3±16.8)°。根据Mayo法评价术后患肘功能:优8例,良4例,中1例,优良率为92.3%。结论 解剖型锁定钢板联合Lost K-wire技术治疗Schatzker B型尺骨鹰嘴骨折能有效恢复并维持半月切迹关节面平整,增加关节面的稳定性,有利于早期功能锻炼,近期临床疗效满意。     

The relationship between main elbow flexion skin crease and osseous anatomy of the elbow joint

Background  Studies that investigate the relationships between the main elbow flexion crease and the underlying osseous anatomy are lacking. Methods  The relationship between the flexion skin crease and osseous anatomy of the elbow joint was studied. Markers were placed along the main flexion skin crease of both elbows in 50 healthy volunteers. Measurements were expressed in millimeters of perpendicular distance from each skin crease to the osseous structures of the elbow joint including medial and lateral epicondyles, tip of the olecranon, and radial head. Results  The mean perpendicular distances between the elbow crease from osseous structures were found to be as follows: from medial epicondyle, 6.93 mm; from lateral epicondyle, −0.25 mm; from olecranon, 9.97 mm; and from radial head, −21.97 mm. There was no statistical significant difference between the dominant versus non-dominant hand. Conclusions  The association between the main flexion elbow crease and the bony structures observed in this study seems to support that the elbow crease can be a useful surface anatomy landmark and expected to aid in the placement of surgical incisions.     

Kinematics of a cementless mobile bearing posterior cruciate ligament-retaining total knee arthroplasty

Mobile bearing (MB) total knee arthroplasty (TKA) was developed to provide low contact stress and unconstrained joint motion. We studied a consecutive series of 41 knees with mobile-bearing, posterior cruciate-retaining (CR) TKAs to determine if kinematics resembled normal knees or if kinematics changed over time. Patients were studied at 3 and 21 months average follow-up with weight-bearing radiographs at full extension, 30° flexion and maximum flexion. Shape-matching techniques were used to measure TKA kinematics. Implant hyperextension, maximum flexion and total ROM increased with follow-up. Tibial rotation and condylar translations did not change with time. The medial condyle did not translate from extension to 30°, but translated 5 mm anteriorly from 30° to maximum flexion. Lateral condylar translation was 3 mm posterior from extension to 30°, with no translation from 30° to maximum flexion. Tibiofemoral kinematics in CR-MB-TKAs were stable over time, but did not replicate motions observed in healthy knees. The mobile tibial insert showed rotation and translation at both follow-up examinations, but the patterns of translation were not predictable.     

The mechanical hypothesis of septal aperture formation tested in an early medieval population from Ostrów Lednicki (Poland)

The aetiology of septal aperture formation is still an open question. The influence of bone robusticity, osteoarthritis, osteoporosis, and the size and shape of ulnar processes has been discussed. Some researchers have shown that weaker muscles lead to greater joint hypermobility, the impingement of ulnar processes on the humeral lamina, and, consequently, septal aperture formation. Assuming this theory is correct, the question is whether flexion or extension or both play a role in septal lamina perforation. The aim of the study was to examine the mechanical hypothesis of septal aperture formation in samples of skeletal material derived from an early medieval cemetery in Ostrów Lednicki (Poland). A total of 136 pairs of bones (humeri and ulnae) were examined. Septal aperture was scored as present or absent. Entheseal changes in ulna were used as markers of activity patterns, especially involving elbow extension and flexion. Entheseal changes were assessed based on a three‐point rating scale. A significant negative correlation between septal aperture and triceps muscles was noted in right bones in females (τ = –0.331) and in both sexes combined (τ = ?0.322). The relationship between septal aperture and the brachialis muscle was positive but non‐significant. This means that looser triceps lead to greater looseness of the elbow, greater protrusion of the olecranon process, and consequent septal aperture formation. Different results were obtained for the brachialis, which may suggest that forearm flexion does not significantly affect septal lamina perforation.     

老年人左、右手喝水动作的运动特性研究

目的通过采集和分析人体三维运动数据,研究老年人左、右手喝水动作的运动学特性。分析左、右手动作的差异,为镜像康复设备的设计和精准康复训练方案的制定提供数据支持和理论基础。方法选取16名右利手的老年人为实验对象,实验对象分别用左、右手完成喝水动作。应用运动捕捉系统采集实验者上肢的三维运动轨迹,分析实验对象在喝水动作中,左、右肩、肘、腕关节的三维运动角度和角速度的相关性。结果左、右手在肩关节的矢状轴角度、肘关节的屈伸角度、肩关节的旋内旋外角度、肘关节旋内旋外的角度上具有高度相关性(相关系数r0.8);在肩关节冠状轴的角度、腕关节掌屈背伸的角速度上具有低度相关性(0.3r0.5);在肩关节冠状轴的角速度上具有微弱相关性(0.1r0.3);在其余上肢的关节角度和角速度上具有显著相关性(0.5r0.8)。结论健康老年人在完成喝水动作中,主要利用肩关节的旋内旋外活动和肘关节的屈伸、旋内旋外活动。右手在关节屈伸角度的运动幅度上大于左手,而在关节旋内旋外角度的运动幅度方面小于左手。在镜像康复机器人设计和康复轨迹规划中,应尊重左、右手的差异,实现精准康复的目的。     

Relationship between stretch reflex thresholds and voluntary arm muscle activation in patients with spasticity

Previous studies have shown that deficits in agonist–antagonist muscle activation in the single-joint elbow system in patients with spastic hemiparesis are directly related to limitations in the range of regulation of the thresholds of muscle activation. We extended these findings to the double-joint, shoulder-elbow system in these patients. Ten non-disabled individuals and 11 stroke survivors with spasticity in upper limb muscles participated. Stroke survivors had sustained a single unilateral stroke 6–36 months previously, had full pain-free passive range of motion of the affected shoulder and elbow and had some voluntary control of the arm. EMG activity from four elbow and two shoulder muscles was recorded during quasi-static (<5°/s) stretching of elbow flexors/extensors and during slow voluntary elbow flexion/extension movement through full range. Stretches and active movements were initiated from full elbow flexion or extension with the shoulder in three different initial positions (60°, 90°, 145° horizontal abduction). SRTs were defined as the elbow angle at which EMG signals began to exceed 2SD of background noise. SRT angles obtained by passive muscle stretch were compared with the angles at which the respective muscles became activated during voluntary elbow movements. SRTs in elbow flexors were correlated with clinical spasticity scores. SRTs of elbow flexors and extensors were within the biomechanical range of the joint and varied with changes in the shoulder angle in all subjects with hemiparesis but could not be reached in this range in all healthy subjects when muscles were initially relaxed. In patients, limitations in the regulation of SRTs resulted in a subdivision of all-possible shoulder-elbow arm configurations into two areas, one in which spasticity was present (“spatial spasticity zone”) and another in which it was absent. Spatial spasticity zones were different for different muscles in different patients but, taken together, for all elbow muscles, the zones occupied a large part of elbow-shoulder joint space in each patient. The shape of the boundary between the spasticity and no-spasticity zones depended on the state of reflex inter-joint interaction. SRTs in single- and double-joint flexor muscles correlated with the positions at which muscles were activated during voluntary movements, for all shoulder angles, and this effect was greater in elbow flexor muscles (brachioradialis, biceps brachii). Flexor SRTs correlated with clinical spasticity in elbow flexors only when elbow muscles were at mid-length (90°). These findings support the notion that motor impairments after CNS damage are related to deficits in the specification and regulation of SRTs, resulting in the occurrence of spasticity zones in the space of elbow-shoulder configurations. It is suggested that the presence of spatial spasticity zones might be a major cause of motor impairments in general and deficits in inter-joint coordination in particular in patients with spasticity.     

脊柱颈胸结合部C5~T2三维有限元建模与验证

目的基于CT图像数据建立人体脊柱颈胸结合部C5~T2的三维有限元模型,并验证模型的正确性和有效性。方法采用Mimics、Geomagic和Hypermesh软件对人体脊柱颈胸结合部C5~T2椎体进行三维重建、模型修复和有限元前处理,对模型顶面施加±0.5、1、1.5、2 N·m扭矩,用于模拟人体前屈和后伸活动时所产生的载荷作用,使用ANSYS软件计算脊柱颈胸结合部C5~T2节段在前屈和后伸承受扭矩载荷作用时的关节活动度(range of motion,ROM),将计算结果与前人研究结果进行对比分析。结果人体脊柱颈胸结合部C5~T2三维模型中C5~6、C6~7、C7~T1和T1~2各节段椎体在1 N·m载荷作用下,前屈时ROM分别为4.30°、3.21°、1.66°和1.41°,后伸时ROM分别为3.47°、2.86°、0.96°和0.92°。前屈时最大应力出现在椎体前缘,后伸时椎体后缘出现较大应力。ROM和应力分布的趋势与前人研究结果相一致。结论建立的脊柱颈胸结合部三维模型精确逼真,符合脊柱颈胸结合部的生物力学特性,模拟结果可为临床病理研究和颈胸部手术术式的评价提供理论依据。     

3D kinematics of the glenohumeral joint during abduction motion: an ex vivo study

The clinical tolerance of rotator cuff tears is extremely variable, so the question is, what is the role of the deltoid in the shoulder stability? First of all, ex vivo experiments are necessary to analyse its effect. The aims of this study were: (1) to propose a testing protocol to measure the glenohumeral joint kinematics during the abduction motion by pulling on the deltoid without constraining the humerus and (2) to evaluate the repeatability of the 3D measurements. Six fresh-frozen anatomic specimens were tested. The kinematics follow-up of the osseous parts was carried out using an optoelectronic system (Polaris^®, NDI, Canada). The abduction motion is realized by the pulling on anterior and medium fibers of the deltoid. For a 25 mm displacement, the range of motion: for the abduction was 24° to 30.5°, for the flexion was 1.5° to ?30.5° (extension), for the medio-lateral rotation was 12° (lateral rotation) to ?5° (medial rotation). For a displacement of the whole acromion-clavicle between 0 and 25 mm, the three humeral head translations were less than 5 mm. The three rotations and three translations were (with SD 95%): abduction: 0.5°, flexion: 1°, medio-lateral rotation: 1.5°, three translations: 0.5 mm. The results showed a very high repeatability of the values. Results suggest that the deltoid alone can realize a motion of lateral elevation with a good stability in the glenohumeral joint as shown by the slight translation motion of the head and the value reproducibility. The protocol can be used to validate a finite element model of the glenohumeral joint.     

Development and Validation of a Computational Musculoskeletal Model of the Elbow and Forearm

Computational modeling is a powerful tool to study normal, injured, and repaired joint function. Existing musculoskeletal models of the elbow have all limited their applicability by assuming fixed joint axes of rotation or prescribing specific kinematics. The purpose of this study was to develop and validate a model of the elbow and forearm whereby joint behavior was dictated by articular contact, ligamentous constraints, muscle loading, and external perturbations. A three-dimensional computer representation of the humerus, ulna, and radius was produced from computed tomography scans, ligaments were modeled as linear springs, select muscles were represented as constant-magnitude force vectors, and reaction forces were automatically applied at points of bone-to-bone contact. A commercial rigid body dynamics program was used to simulate joint function, and validation was accomplished through a comparison of model predictions to results obtained in published studies which explored elbow range of motion and the effects of coronoid process removal on joint stability. The computational model accurately predicted flexion–extension motion limits, and relationships between coronoid process removal, flexion angle, and varus constraining forces. The model was also able to compute parameters that the experimental investigations could not, such as forces within ligaments and contact forces between bones. The potential medical applications for this model and modeling approach are significant, and are anticipated to ultimately have value as a predictive clinical tool.     

Three-dimensional morphology of the distal femur based on surgical epicondylar axis in the normal elderly population

BackgroundWe aimed to analyze the surface morphology of the distal femur in three dimensions for the healthy elderly, based on the concept that the surgical epicondylar axis (SEA) is a better surrogate for the flexion–extension axis of the knee joint.MethodsWe studied 77 healthy elderly volunteers (40 males and 37 females; age, 68 ± 6 years). The medial and lateral contact lines were calculated three-dimensionally, using the highest points of the medial and lateral condyles in 201 cross-sectional planes around the SEA (every 1°, −60° (hyperextension) to 140° (flexion)). A piecewise fitting function consisting of two linear segments was applied to detect the inflection point of the constant radii in the sagittal plane. The main assessment parameters were knee flexion angle at the inflection point of the radius (inflection angle), mean radius from 0° to the inflection angle (constant radius), and coronal tilt angle of the contact line.ResultsThe inflection angles, constant radii, and coronal tilt angles were 78.2 ± 8.6°, 26.1 ± 2.3 mm, and −0.6 ± 3.2° and 65.6 ± 9.2°, 23.9 ± 2.2 mm, and 6.2 ± 3.2° in the medial and lateral condyles, respectively (all, P < 0.001). The coronal alignment was 88.7 ± 2.2°.ConclusionsThe medial and lateral femoral condyles showed asymmetrical morphologies with the almost ‘constant’ radius of sagittal curvature from 0° to around 80° and 65° of knee flexion, respectively.     

Computational Model of the Human Elbow and Forearm: Application to Complex Varus Instability

Computational modeling is an effective way to predict the response of complex systems to perturbations that are difficult or impossible to measure experimentally. A computational model of the human elbow was developed wherein joint function was dictated by three-dimensional osteoarticular interactions, soft tissue constraints, muscle action, and external loading. The model was validated against two cadaveric experiments that examined the significance of coronoid process (CP) fractures, lateral ulnar collateral ligament (LUCL) ruptures, and radial head (RH) resection in varus stability. The model was able to accurately reproduce the trend of decreasing resistance to varus displacement with increased CP resection, with a significant drop in stability observed at >50% resection. In addition, the model showed that isolated repair of either the LUCL or RH conferred significant varus stability to the joint in the presence of a deficient coronoid, with the ligament responsible for the greatest increase in stability. Predicted magnitudes of joint contact force support claims that the ulnohumeral articulation is the most significant osseous stabilizer of the joint in varus, with the radiohumeral articulation having an increased role with increasing coronoid resection at low flexion angles. With confidence in the predictive ability of this computational model, future simulations could further investigate joint function under other loading scenarios and injury states.     

Effect of 3D physiological loading and motion on elastohydrodynamic lubrication of metal-on-metal total hip replacements

An elastohydrodynamic lubrication (EHL) simulation of a metal-on-metal (MOM) total hip implant was presented, considering both steady state and transient physiological loading and motion gait cycle in all three directions. The governing equations were solved numerically by the multi-grid method and fast Fourier transform in spherical coordinates, and full numerical solutions were presented included the pressure and film thickness distribution. Despite small variations in the magnitude of 3D resultant load, the horizontal anterior–posterior (AP) and medial–lateral (ML) load components were found to translate the contact area substantially in the corresponding direction and consequently to result in significant squeeze-film actions. For a cup positioned anatomically at 45°, the variation of the resultant load was shown unlikely to cause the edge contact. The contact area was found within the cup dimensions of 70–130° and 90–150° in the AP and ML direction respectively even under the largest translations. Under walking conditions, the horizontal load components had a significant impact on the lubrication film due to the squeeze-film effect. The time-dependent film thickness was increased by the horizontal translation and decreased during the reverse of this translation caused by the multi-direction of the AP load during walking. The minimum film thickness of 12–20 nm was found at 0.4 s and around the location at (95, 125)°. During the whole walking cycle both the average and centre film thickness were found obviously increased to a range of 40–65 nm, compared with the range of 25–55 nm under one load (vertical) and one motion (flexion–extension) condition, which suggested the lubrication in the current MOM hip implant was improved under 3D physiological loading and motion. This study suggested the lubrication performance especially the film thickness distribution should vary greatly under different operating conditions and the time and location that potential wear may occur was very sensitive to specific loading and motion conditions. This may provide some explanation to the large variations in wear from hip simulators and clinical studies, and also stress the importance of using more realistic loading and motion conditions in the tribological study of MOM hip prostheses.     

双柱固定原则在骨质疏松性AO 13C型骨折的临床应用和疗效分析

目的 运用双柱固定原则,手术治疗AO 13C型骨质疏松性骨折,评价患者肘关节重建情况及其功能。方法对本院骨科自2008年1月至2017年12月期间治疗的54例AO 13C型骨质疏松性骨折的患者进行回顾性分析,均采用切开复位肱骨远端解剖型LCP双钢板固定治疗。本组患者男21例,女33例;平均年龄(65.4±5.8)岁;根据AO/ASIF分型,13C1型21例,13C2型27例,13C3型6例;受伤至手术时间平均(7.9±1.6)d。用Mayo Clinic肘关节功能评分标准来评估手术疗效。结果 平均随访时间(20.8±2.1)个月。平均手术时间103.5min;平均骨折愈合时间(13.5±1.0)周。术后伸肘平均9.4°±5.6°,屈肘平均108.1°±7.4°,活动范围平均99.2°±10.3°。Mayo Clinic肘关节功能评估平均(84.7±8.1)分;优20例,良29例,中5例,差0例。结论 运用双柱固定原则,使用解剖型LCP治疗AO 13C型骨质疏松性骨折临床效果优良,肘关节功能恢复良好。     

Morphological integration in the forelimb of musteloid carnivorans

The forelimb forms a functional unit that allows a variety of behaviours and needs to be mobile, yet at the same time stable. Both mobility and stability are controlled, amongst others, at the level of the elbow joint. This joint is composed of the humero‐ulnar articulation, mainly involved during parasagittal movements; and the radio‐ulnar articulation, mainly allowing rotation. In contrast, the humero‐radial articulation allows both movements of flexion–extension and rotation. Here, we study the morphological integration between each bone of the forelimb at the level of the entire arm, as well as at the elbow joint, in musteloid carnivorans. To do so, we quantitatively test shape co‐variation using surface 3D geometric morphometric data. Our results show that morphological integration is stronger for bones that form functional units. Different results are obtained depending on the level of investigation: for the entire arm, results show a greater degree of shape co‐variation between long bones of the lower arm than between the humerus and either bone of the lower arm. Thus, at this level the functional unit of the lower arm is comprised of the radius and ulna, permitting rotational movements of the lower arm. At the level of the elbow, results display a stronger shape co‐variation between bones allowing flexion and stability (humerus and ulna) than between bones allowing mobility (ulna and radius and humerus and radius). Thus, the critical functional unit appears to be the articulation between the humerus and ulna providing the stability of the joint.