UNIVERS 3-D肩关节假体置换治疗盂肱关节不稳性骨关节炎

目的评价UNIVERS3-D肩关节假体置换治疗盂肱关节不稳性骨关节炎的临床效果。方法采用UNIVERS3-D肩关节假体置换治疗16例盂肱关节不稳性骨关节炎,平均随访30.8个月(12～50个月),术前、术后12个月及最后随访均进行功能评估和摄X线片。功能评估采用Constant评分和Constant修正评分;评分内容包括:疼痛、日常生活、活动范围和肌力评分;根据性别及随访时的年龄进行功能修正评分。采用t检验对术前、术后12个月及最后随访的Constant评分和Constant修正评分进行统计学分析。X线片包括:前后位、轴位和“Y”型位。结果术前盂肱关节不稳性骨关节炎肱骨头、盂唇下缘外生骨赘轻度占72.7%(8/11)。Constant功能评分从术前(43.8±13)分(修正评分51.36%±15.40%)提高到(70.6±17.69)分(修正评分86.44%±22.12%)。疼痛、日常生活、活动范围和肌力评分术后均较术前有明显的提高。肱骨假体无松动、下沉和倾斜,盂假体无松动、位移和倾斜。无肱骨假体头-颈连接部的松动和脱位。1例出现肱骨假体周围X线透亮带,透亮带系数小于1,即没有松动。2例发生并发症,1例由骨赘引起假体间撞击征,1例聚乙烯衬垫松动。结论UNIVERS3-D肩关节假体置换治疗盂肱关节不稳性骨关节炎术后较术前功能有明显的提高,X线透亮带发生率及并发症发生率低。     

反式全肩关节置换治疗盂肱关节骨关节炎伴巨大肩袖撕裂

目的探讨反式全肩关节置换术治疗盂肱关节骨关节炎合并巨大肩袖撕裂的近期临床疗效。 方法回顾性分析2016年1月至2018年12月在南部战区总医院接受初次反式全肩关节置换术治疗的15例盂肱关节骨关节炎合并巨大肩袖撕裂患者,均有肩关节持续性疼痛、功能障碍,且三角肌无损伤具有功能;排除有臂丛或腋神经损伤以及有肩关节手术史的患者。评估其术前、术后1年的肩关节主动活动度,使用美国肩肘外科协会(ASES)肩关节评分、加州大学洛杉矶分校(UCLA)最终结果评分评价肩关节功能,分析X线及CT并发症出现情况。采用配对t检验对术前及术后的活动度和评分差异进行性分析。 结果15例患者均顺利完成手术并获得随访,随访时间17个月(范围12～36个月)。反式全肩关节置换术后1年肩关节主动前屈(124±11)°较术前(58±18)°提高(t＝14.316,P<0.01),外展(120±12)°较术前(58±20)°提高(t＝9.959,P<0.01),内旋较术前改善,外旋(26±8)°较术前(25±9)°无明显变化(t＝1.598,P>0.05),术后1年ASES评分(78±7)显著高于术前(33±8)(t＝16.487,P<0.01);术后1年UCLA评分(31±4)显著高于术前(15±3)(t＝12.826,P<0.01)。 结论RTSA能够有效治疗盂肱关节骨关节炎合并巨大肩袖撕裂,取得了良好的早期临床效果,但术后肩关节外旋无明显改善,术前需评价小圆肌情况以确定相关治疗方案。     

非限制性肩关节置换术

目的：作者对２９例肩关节炎和肱骨近端骨折患者的３６侧肩关节，采用非限制性假体做全肩关节置换术２４个、半肩（即人工肱骨头）置换术１２个。方法：所有３６个肱骨头假体和１３个肩盂假体为骨长入型非骨水泥假体，余１１个肩盂假体为骨水泥假体。患者术时平均年龄６３岁，术后平均随访６．２年（３．３～１０．４年）。结果：术后肩关节疼痛缓解率达９１．３％，主动活动度增加：前屈４７°、外展４３°、外旋３０°、内旋４个节段。６个日常生活动作能力平均评分由术前０．８分增加到术后３．１分。术后Ｘ线片示肱骨头假体上移８例，其中６例伴有肩袖撕裂甚或缺损。１例肱骨头假体和９例肩盂假体周围可见Ｘ线透亮线。肱骨头假体松动１例；肩盂假体松动２例。结论：显示非限制性肩关节置换术是一种疗效可靠满意的手术方法     

非限制性人工肩关节置换治疗肩关节和肱骨近端严重病损

目的观察并评估非限制性人工肩关节置换治疗肩关节及肱骨近端严重病损的疗效。方法自1999～2004年共进行11例人工肩关节置换术,患者平均年龄为65岁；肱骨近端复杂四部分骨折6例,陈旧性肱骨解剖颈骨折并脱位3例,肩关节骨关节炎2例。其中对2例肩关节骨关节炎采用非限制性假体全肩关节置换术,对9例复杂肱骨近端骨折采用非限制性假体半肩置换术。所有11个肱骨头假体和2个肩盂假体均使用骨水泥固定。结果所有患者均获得随访,时间为1～4年,平均2．3年。2例复杂骨折患者存在肩关节外旋部分受限和轻度疼痛,其余病例均无疼痛,假体无松动。采用Neer评分和美国矫形外科学会评定标准,术后Neer评分平均为88．7分,评定为满意,肩关节功能满意。结论非限制性人工肩关节置换治疗肱骨近端严重病损疗效可靠、安全,精确的假体安置、软组织修复及术后系统的康复训练是关节功能恢复及降低并发症的关键。     

肩关节置换术研究进展

肩关节置换术在过去30年间取得了巨大发展,最重要的进步来源于外科技术的发展,例如出现了压实骨移植法、"锉盂和活动重塑"法等。非骨水泥表面置换型假体具有一定的疗效,假体材料的改进有益于肩关节置换术的成功,一些方法在提高关节盂假体寿命上起了重要作用。理想的关节盂假体设计方案仍未取得一致,全聚乙烯、骨水泥、弧板设计是目前较好的选择。中长期研究显示,全肩关节置换术疗效优于半肩关节置换术,但存在关节盂假体长期松动问题,或许关节盂生物表面重建(成形)术是解决问题方法之一。肱骨头假体与关节盂假体最佳不匹配降低透亮线和松动发生率,而逆置式假体也有其应用指征。需进一步进行大样本、多中心的随机对照试验来解决肩关节置换术的基本问题,即应用哪种类型置换术和固定方法。实验室生物力学研究是临床研究的基础,主要集中于关节盂假体松动及假体周围出现透亮线意义的研究。     

人工肩关节表面置换术的应用

随着基础研究的进展和临床经验的积累,经过近二十年的发展,人工肩关节表面置换已成为一种治疗盂肱关节严重疾病的选择。与传统的人工肩关节置换术（包括肱骨头置换术和人工全肩关节置换术两大类）相比,表面置换只是磨去肱骨头的一部分,在肱骨头的剩余部分放上合成金属“帽”。由于其创伤小,恢复快,骨量丢失少等优点,在临床上运用越来越广泛。本文就肩关节表面置换的历史发展,假体设计的生物力学机制,假体类型,手术指征,禁忌证,手术技术以及临床短、中期随访结果做一个全面的综述。     

人工肩关节置换术研究进展

人体活动范围最大的肩关节的三维空间功能活动得益于肩关节骨性结构盂肱关节、肩锁关节、胸锁关节、肩胛骨的运动或旋转,以及周围肌肉和韧带组织对功能运动和稳定性的维持.人工肩关节假体的设计比人工髋关节、膝关节假体更复杂,仍不如人工髋关节、膝关节置换术满意.为避免人工肩关节置换术后并发症及改善预后,熟悉肩关节的解剖和力学机制、掌握精确的关节重建技术、合理选择假体尤为重要.该文就肱骨头假体设计的解剖学基础、关节盂假体、半肩置换与全肩置换的选择及影响预后的因素等方面的研究进展作一综述.     

半或全肩关节置换治疗肱骨近端严重病损

[目的]探讨采用半或全肩关节置换术治疗肱骨近端严重病损的手术适应证、手术要点以及假体的选择。[方法]选择12例患者,全肩关节置换4例,半肩关节置换8例;肱骨四分骨折6例,肱骨头坏死2例,肱骨头合并关节盂坏死1例,类风湿关节炎合并肩关节强直2例,骨巨细胞瘤1例。采用美国肩肘关节医师协会肩关节评估表对肩关节进行术后功能评估。平均随访14个月。[结果]9例无痛,3例轻微疼痛,12例均无松动,肩关节平均外展100°,10例患者对治疗效果表示满意。[结论]半或全关节置换是一种治疗肱骨近端严重病损的有效方法,成功的关键在于科学的手术治疗方案、适宜的假体和有效的康复计划。     

关节镜下双后入路结合前方入路盂肱关节囊松解治疗重度原发性冻结肩

目的研究肩关节镜双后入路结合前方入路盂肱关节囊松解治疗重度原发性冻结肩的临床效果。 方法2013年1月至2016年12月南京中医药大学附属医院对16例重度原发性冻结肩患者行关节镜下双后入路结合前方入路盂肱关节囊松解术,男2例、女14例,平均年龄46.6岁,左肩4例、右肩12例。所有患者术前均拍摄肩关节正位片、冈上肌出口位X线片和肩关节MRI检查,全部患者均行双后入路关节镜下盂肱关节囊松解术,所有病例均同时行肩峰下滑囊清理术,分别在术前和末次随访时采用视觉模拟评分（visual analogue scale,VAS）、Constant-Murley评分和美国加利福尼亚大学（University of California, Los Angeles,UCLA）肩关节评分标准进行评价。 结果随访时间10~37个月,平均26个月。术前、术后即刻和末次随访平均UCLA评分分别为（10.3±3.2）分、（28.2±3.3）分和（31.2±5.3）分,差异有统计学意义（P<0.01）;平均Constant-Murley评分为（38.3±4.2）分、（89.2±4.5）分和（95.2±3.3）分;VAS评分平均为（6.3±1.9）分、（1.3±0.3）分和（1.0±0.2）分（P<0.01）。所有患者均对手术效果表示满意。 结论关节镜下双后入路结合前方入路盂肱关节囊松解治疗重度原发性冻结肩,便于术中操作,可以显著地缓解疼痛、恢复肩关节功能。关节镜下双后入路结合前方入路盂肱关节囊松解为治疗重度原发性冻结肩提供有效方法。     

反向关节置换术中采用不同直径盂球假体治疗肩关节损伤的疗效比较

目的比较反向关节置换术(RAS)中采用不同直径盂球假体治疗肩关节损伤的临床疗效。方法回顾性分析自2010-01—2014-12采用RAS治疗的41例肩关节损伤,19例术中采用直径为42 mm的盂球假体(观察组),22例术中采用直径为38 mm的盂球假体(对照组),比较2组术后肩胛骨切迹形成情况、术后2年Constant评分,术后2年RAS术后有肩胛骨切迹形成与无肩胛骨切迹形成Constant评分。结果 41例均获得随访,随访时间14.5±2.8(12~24)个月,未出现切口感染,观察组出现1例肩关节脱位,对照组出现1例肩关节脱位,对症治疗后治愈。术后2年观察组肩胛骨切迹等级较对照组优,Constant评分较对照组高,前方上举角度较对照组大,盂球假体悬垂高度较对照组高,差异有统计学意义(P <0.05),术后2年15例RAS术后有切迹成形者Constant评分较26例RAS术后无切迹成形者低,差异有统计学意义(P <0.05)。结论 RSA术中使用较大直径的盂球假体能够有效降低患者术后肩胛骨切迹形成,促进患者术后肩关节功能的恢复,同时RSA术后肩胛骨切迹的形成将影响患者术后肩关节功能的改善。     

Current status and perspectives of shoulder replacement

Summary Basis of the modern shoulder implants is the Neer II-system, a non constrained total shoulder prosthesis with conforming radii of curvature and improved protection against dislocation. The second generation of shoulder prosthesis is based on the geometric shaft design of the Neer II prosthesis and offers not only a variety of modular head- and shaft-sizes but also through different radii a physiologic rotation-translation-mechanism. The third generation of humeral head prosthesis carries the concept of an anatomic reconstruction one step further and enables the surgeon to adjust the inclination and the eccentric offset of the humeral head to restore the centre of rotation. The latest development in shoulder arthroplasty are humeral head prosthesis with a fully variable 3-dimensional modularity to independently adjust the prosthestic head position regardless of the individual shaft geometry. This achieves a 3-dimensional adaptability of the prosthetic head about the stem axis in the coronary and in the sagittal plane. Besides of the humeral shaft prosthesis an alternative concept of shoulder joint replacement is established – the replacement of the humeral head articular surface. A hemispheric surface prosthesis – cup arthroplasty – is cemented onto the residual humeral head, which eliminates the obligatory humeral head resection and the reaming of the medullary canal. Bipolar shoulder prosthesis are humeral shaft prosthesis with a bi-rotational head system. Their indication is limited to pre-existing lesions of the rotator cuff and/or the glenoid surface. The inverse total shoulder prosthesis reverses the articular surface morphology of the humeral head and the glenoid. The hemispheric glenoid component serves as the centre of rotation for the concave epiphyseal proximal humerus component. This implant is especially used in cases of massive rotator cuff deficiences. The role of shoulder prosthesis in treating acute humeral head fractures needs special consideration. A fracture prosthesis has to restore the exact length of the humerus, the centre of rotation, and the anatomical retroversion. Positioning of the tubercula and their adequate osteosynthesis is most critical and fundamental to ensure a correct healing process. A failed consolidation of the tubercula does not lead to a satisfying result. The shoulder joint replacement can be sufficiently fixated in cemented, cementless or hybrid techniques. Today several component design variations of cemented glenoid implants exist. Their main distinction is the fixation system which can be divided into two main groups – the keel – and the peg-shaped glenoid components. The peg-shaped anchorage system shall guarantee a greater stability against shear-forces. Cementless glenoid components consist of a polyethylen inlay and a surface treated metal-back with an integrated fixation system. These fixation systems are object of intensive biomechanical research and range from conventional screw fixation to specialised cone systems and self-cutting cage-screw-systems. The critical area of cementless glenoid components is the transition zone of the PE-inlay and the metal-back because of high force development. The question of implanting a hemi- or total shoulder prosthesis is answered by the morphologic changes of the glenoid articular surface, which includes the size of the subchondral defect and the underlying etiology of the shoulder joint disease, and the age of the patient. Preoperative planning must consist of an adequate radiologic work-up – X-ray, CT or MRI – to accurately assess the glenoid morphology. G. Walch categorised the different glenoid lesions and developed a very important classification of possible glenoid deformations. To compare and evaluate the operative results one must consider the different shoulder prosthesis and the discrepancies between a hemi- and a total shoulder prosthetic replacement. Looking at the loosening and survival rate of the implant the results are related to the type of prosthesis and the preoperative diagnosis. The Neer total shoulder prosthesis has a 15 year survival rate of 87 %, compared to 74 % of the hemi-prosthesis. The objective for the future has to be to further advance the development of prosthetic components, especially for primary joint replacement in acute humeral head fractures. Another point of interest is how to reduce the still existing high loosening rates of the glenoid components. A fairly new research-field is the computer-assisted surgery, e. g. navigation systems and robotics. The computer-assisted navigation could be of great advantage to accurately find the individual resection plane (inclination and restroversion) of the humeral head. The use of a surgery-robot could be very helpful to reproducibly achieve the desired conformity of the articular surface when preparing the glenoid.      

Current status and perspectives of shoulder replacement

Basis of the modern shoulder implants is the Neer II-system, a non constrained total shoulder prosthesis with conforming radii of curvature and improved protection against dislocation. The second generation of shoulder prosthesis is based on the geometric shaft design of the Neer II prosthesis and offers not only a variety of modular head- and shaft-sizes but also through different radii a physiologic rotation-translation-mechanism. The third generation of humeral head prosthesis carries the concept of an anatomic reconstruction one step further and enables the surgeon to adjust the inclination and the eccentric offset of the humeral head to restore the centre of rotation. The latest development in shoulder arthroplasty are humeral head prosthesis with a fully variable 3-dimensional modularity to independently adjust the prosthestic head position regardless of the individual shaft geometry. This achieves a 3-dimensional adaptability of the prosthetic head about the stem axis in the coronary and in the sagittal plane. Besides of the humeral shaft prosthesis an alternative concept of shoulder joint replacement is established – the replacement of the humeral head articular surface. A hemispheric surface prosthesis – cup arthroplasty – is cemented onto the residual humeral head, which eliminates the obligatory humeral head resection and the reaming of the medullary canal. Bipolar shoulder prosthesis are humeral shaft prosthesis with a bi-rotational head system. Their indication is limited to pre-existing lesions of the rotator cuff and/or the glenoid surface. The inverse total shoulder prosthesis reverses the articular surface morphology of the humeral head and the glenoid. The hemispheric glenoid component serves as the centre of rotation for the concave epiphyseal proximal humerus component. This implant is especially used in cases of massive rotator cuff deficiences. The role of shoulder prosthesis in treating acute humeral head fractures needs special consideration. A fracture prosthesis has to restore the exact length of the humerus, the centre of rotation, and the anatomical retroversion. Positioning of the tubercula and their adequate osteosynthesis is most critical and fundamental to ensure a correct healing process. A failed consolidation of the tubercula does not lead to a satisfying result. The shoulder joint replacement can be sufficiently fixated in cemented, cementless or hybrid techniques. Today several component design variations of cemented glenoid implants exist. Their main distinction is the fixation system which can be divided into two main groups – the keel – and the peg-shaped glenoid components. The peg-shaped anchorage system shall guarantee a greater stability against shear-forces. Cementless glenoid components consist of a polyethylen inlay and a surface treated metal-back with an integrated fixation system. These fixation systems are object of intensive biomechanical research and range from conventional screw fixation to specialised cone systems and self-cutting cage-screw-systems. The critical area of cementless glenoid components is the transition zone of the PE-inlay and the metal-back because of high force development. The question of implanting a hemi- or total shoulder prosthesis is answered by the morphologic changes of the glenoid articular surface, which includes the size of the subchondral defect and the underlying etiology of the shoulder joint disease, and the age of the patient. Preoperative planning must consist of an adequate radiologic work-up – X-ray, CT or MRI – to accurately assess the glenoid morphology. G. Walch categorised the different glenoid lesions and developed a very important classification of possible glenoid deformations. To compare and evaluate the operative results one must consider the different shoulder prosthesis and the discrepancies between a hemi- and a total shoulder prosthetic replacement. Looking at the loosening and survival rate of the implant the results are related to the type of prosthesis and the preoperative diagnosis. The Neer total shoulder prosthesis has a 15 year survival rate of 87 %, compared to 74 % of the hemi-prosthesis. The objective for the future has to be to further advance the development of prosthetic components, especially for primary joint replacement in acute humeral head fractures. Another point of interest is how to reduce the still existing high loosening rates of the glenoid components. A fairly new research-field is the computer-assisted surgery, e. g. navigation systems and robotics. The computer-assisted navigation could be of great advantage to accurately find the individual resection plane (inclination and restroversion) of the humeral head. The use of a surgery-robot could be very helpful to reproducibly achieve the desired conformity of the articular surface when preparing the glenoid.     

复杂肱骨近端骨折人工肱骨头置换术中肩袖重建的长期疗效观察

目的探讨Neer 3、4部分肱骨近端骨折人工肱骨头置换术中肩袖重建的远期临床效果。方法回顾性分析自2001-01—2012-12采用人工肱骨头置换术治疗的25例Neer 3、4部分肱骨近端骨折。术前测量健侧大结节最低点至肱骨头最高点的距离,术中尽量解剖复位肱骨大、小结节,合理控制假体高度及后倾角度,尽可能修复重建损伤肩袖,术后分阶段康复锻炼。结果本组22例获得有效随访,随访时间平均120(49~190)个月。末次随访时ASES评分为80~92(86.28±3.36)分,肩关节内旋至T10水平,患肢主动前屈上举125°~135°,外旋36°~42°。1例合并臂丛神经损伤者术后肩关节功能恢复满意。结论对于骨折端无法良好复位、肱骨头缺血性坏死可能性大的复杂肱骨近端骨折,人工肱骨头置换同时进行精细的肩袖重建可以获得无痛和良好运动范围的肩关节。     

Design und Biomechanik inverser Schulterprothesen

Reverse shoulder arthroplasty has developed from a salvage procedure for a small group of selected patients with pseudoparalysis to a standard procedure for a variety of shoulder diseases associated with rotator cuff insufficiency. By inversing the joint surfaces the humeral head can be stabilized on the glenoid despite an insufficient rotator cuff. A normal shoulder function, however, cannot be expected after such a procedure. Reverse prostheses medialize the centre of rotation and distalize the humerus. This has an influence on the range of motion, the lever arms, the forces and the stability of the reconstructed joints. The currently used prosthesis models differ in many parameters. The following article describes the most important features and biomechanics of reverse prostheses.     

Prosthetic replacement in rotator cuff-deficient shoulders

We reviewed a series of 30 shoulders in 25 patients who had glenohumeral arthritis and rotator cuff deficiency and who underwent prosthetic replacement. Nineteen shoulders underwent humeral head replacement, and 11 shoulders had total shoulder arthroplasty. Meticulous mobilization and reconstruction of the deficiencies in the thin atrophic rotator cuff tissues were attempted in all shoulders. Emphasis was placed on anteroposterior stability, and this was achieved in all shoulders; superior coverage was fully achieved in 15 shoulders and was partially achieved in 11. All shoulders had less pain after surgery, and 93% achieved satisfactory pain relief. Total shoulder arthroplasty and humeral hemiarthroplasty were found to provide similar results with respect to pain relief, functional improvement, and patient satisfaction. Shoulders with hemiarthroplasty gained significantly more active elevation (+52° vs + 2°) after surgery. Cuff repair was easier when a humeral head prosthesis alone was used because less lateralization of the humerus occurred. Also, operative time, anesthesia time, and blood loss were decreased with hemiarthroplasty. Because the lack of glenoid resurfacing did not adversely affect pain relief or function and avoided the potential problem of glenoid loosening, we favor humeral hemiarthroplasty as a treatment for glenohumeral arthritis in the rotator cuff-deficient shoulder.     

Decision making in glenohumeral arthroplasty

Prosthetic replacement arthroplasty for glenohumeral arthritis is a well-developed and well-described technique with good and excellent results. The surgeon is faced with many decisions to make, however, regarding choice of implant, implant fixation, soft tissue management, and options for glenoid resurfacing. In general, when the precise cause of the arthritic condition is identified, the choices become more straightforward. For advanced osteoarthritis of the shoulder joint in an older patient with asymmetric posterior erosion of the glenoid, a total shoulder arthroplasty renders the best relief of pain and improvement in motion. Similarly, for advanced rheumatoid arthritis in patients with an intact rotator cuff, a total shoulder arthroplasty results in the best pain relief. If the rotator cuff is deficient and irreparable, an anatomically sized humeral head replacement is appropriate, taking care to preserve the coracoacromial arch. Acute, nonreducible fractures of the proximal humerus are treated best with a humeral head replacement. Post-traumatic arthropathy of the shoulder joint is treated with arthroplasty, and the decision to resurface the glenoid should take into account the age of the patient and the wear and concentricity of the glenoid. Many options exist for the choice of an implant; biomechanical and anatomic studies suggest that a better technical result can be achieved with a third-generation implant design that has the ability to recreate accurately the proximal anatomy of the humerus.     

Glenoid loosening in total shoulder arthroplasty. Association with rotator cuff deficiency

Seven cases of total shoulder arthroplasty exhibiting major glenoid radiolucent lines or actual translation of the glenoid component were evaluated to identify factors associated with glenoid loosening. The average time from arthroplasty was 30 months (range, 14-44 months). Six of the patients had severe, incompletely reconstructable rotator cuff tears present at the time of surgery, and one patient developed a cuff tear within 1 year of surgery. The amount of superior migration of the humeral component was closely correlated with the degree of glenoid loosening. With superior displacement of the humeral component, superior tipping of the glenoid component was observed: a "rocking horse" glenoid. For comparison, a contemporary group of 16 consecutive total shoulder arthroplasty patients with intact rotator cuffs were reviewed. The control group had no glenoid loosening an average of 5 years after operation. Upward riding of the prosthetic humeral head in patients with rotator cuff deficiency may contribute to loosening of the glenoid component in total shoulder arthroplasty.     

肱骨外展动作中肩袖生物力学的有限元分析

目的构建肩关节有限元模型，用于分析肩袖生物力学。 方法采集1名26岁健康男性志愿者右肩CT、MRI数据，构建肩关节有限元模型，包含肩胛骨、肱骨、锁骨，以及肩袖肌群（冈上肌、冈下肌、小圆肌、肩胛下肌）。模拟肱骨在肩胛骨平面外展，分析肩袖肌肉应力变化。 结果肱骨在肩胛骨平面外展0°~30°过程中，各组肌腱与肱骨头连接处的应力均增大。冈上肌腱应力变化速率较快；肩胛骨前方的肩胛下肌对比肩胛骨后方的冈下肌-小圆肌，两组肌腱的应力变化较为同步。当肱骨在肩胛骨平面外展30°时，冈上肌腱、肩胛下肌腱及冈下肌腱-小圆肌腱与肱骨头连接面的平均应力分别为7.894 8、4.721 7、3.768 8 Mpa，冈上肌腱关节面与滑囊面结点平均应力分别为7.931 4、4.099 0 Mpa。冈上肌腱的关节面与滑囊面应力有明显差异，应力差值随肱骨在肩胛骨平面外展而增大，造成的剪切力可造成冈上肌腱撕裂。 结论肩袖对肩关节的活动与稳定性有重要作用，其受力特点易引起肩袖损伤。     

The static rotator cuff does not affect inferior translation of the humerus at the glenohumeral joint.

BACKGROUND: The static contribution of the rotator cuff to the inferior stability of the shoulder is poorly understood. The purpose of this study was to determine the effect of static rotator cuff muscles on the inferior stability of the glenohumeral joint. METHODS: The humeral head positions relative to the glenoid were obtained in 12 shoulder specimens under the following conditions: with and without a 1.5-kg load; with the humerus adducted and abducted 90 degrees; and in three stages of dissection: (1) before release of any of the rotator cuff muscles, (2) after release of the supraspinatus or the cuff muscles other than the supraspinatus, and (3) after release of all of the cuff muscles. The order of release was changed in two ways: release of the supraspinatus followed by the release of other muscles in one group, and the opposite order in the other group. RESULTS: In both adduction and abduction, there were no significant differences in the positions of the humeral head either among the three stages of release or between the two different orders of release. CONCLUSION: The static contribution of the cuff muscles to the inferior stability of the shoulder is insignificant.     

Principles of shoulder prosthesis implantation

Patients with an intact rotator cuff and a humeral head that is centered in the glenoid fossa will benefit from both: a hemiarthroplasty and a total shoulder arthroplasty. However, the functional outcome following total shoulder arthroplasty is superior to that of hemiarthroplasty. Superior migration or mal-positioning of the humeral head in the anterior or posterior direction are generally associated with a maximum active flexion of 90 degrees and a high rate of loosening of the glenoid component. Total shoulder arthroplasty leads to superior results in patients with osteoarthritis and mal-positioning of the humeral head in the posterior direction. However, if the head can not be centralized in the glenoid fossa a significant risk of glenoid loosening remains. A superior functional outcome of total shoulder arthroplasty in patients with rheumatoid arthritis can be observed. On the other hand inferior bone quality and a rotator cuff might lead to loosening of the glenoid component. Radiographic signs of glenoid loosening are frequently observed. However, these hardly require operative revisions. If a glenoid component can not be inserted, a bipolar or inverse prosthesis might be considered an alternative.