应用生物力学方法探讨桡骨小头切除术后晚期并发症的原因

自１９７８年，共施行健骨头切除术３７例。２７例获２年以上随访。肘外翻畸形，肘关节慢性不稳定，桡骨干上移和下尺桡关节脱位是主要并发症。作者用２０只新鲜上肢标本进行生物力学实验，发现肘关节内侧副韧带损伤，骨间膜撕裂伤和下尺桡关节脱位是引起或加重并发症的主要原因。其中内侧副韧带损伤是最重要的原因。同时，临床上也以桡骨头损伤合并内侧副韧带损伤多见。作者强调：桡骨头切除时，应考虑上述三种软组织损伤是否存在及其对预后的影响；桡骨头切除在青少年患者应视为禁忌；桡骨头切除应作为改善前臂功能的最后选择。     

人工桡骨头假体置换的临床研究进展

桡骨头骨折是成人肘部最常见的骨折，占肘关节骨折的33％，在成人所有骨折中占1．7％～5．4％。桡骨头骨折还常伴有软组织损伤，如内侧副韧带或骨间膜破裂，当这些组织损伤后，桡骨头就成为维持肘关节轴向和外翻稳定的主要结构。对于不稳定的肘关节，切除桡骨头可发生许多远期并发症，包括桡骨向近端移位，外翻不稳定，肘关节僵硬，肘和腕关节退行性关节炎，肘、前臂和腕关节慢性疼痛。因此，对伴有内侧副韧带和（或）骨间膜损伤的桡骨小头粉碎性骨折通常采用人工桡骨头置换术”。     

冠突骨折行桡骨小头切除对肘关节稳定性的实验研究

[目的]桡骨小头粉碎骨折时往往行桡骨小头切除术。本研究目的是分析桡骨小头粉碎骨折伴尺骨冠突骨折时行桡骨小头切除前后肘关节的稳定性。[方法]选取骨密度值相近的上肢标本20对,经X线片证实无风湿、结核、肿瘤、骨折、畸形等。剥离上肢所有的皮肤、肌肉和筋膜,完整保留肘关节囊、内外侧副韧带、环状韧带及尺、桡骨骨间膜。调制好的牙托粉与标本两端固定后,将标本伸直侧位自由放置于生物力学机,关节轴与水平面垂直,肱骨外髁向上,于肱骨外髁处垂直向下载荷,记录肘外翻位移。将标本竖直固定于生物力学机,尺桡骨向下,肘关节伸直位,做肘外旋扭转,记录肘关节的转角。[结果]桡骨小头粉碎骨折伴冠突无骨折、Ⅰ型骨折、Ⅱ型骨折在桡骨小头切除后较切除前肘外翻位移及外旋角经统计学比较各组间并无显著性差异;伴冠突Ⅲ型骨折时在桡骨小头切除后较切除前肘外翻位移及外旋角显著增大。[结论]桡骨小头粉碎骨折伴冠突Ⅰ、Ⅱ型骨折行桡骨小头切除前后肘关节均稳定,可行桡骨小头切除术,Ⅲ型骨折不稳定,应修复桡骨小头或假体置换,并修复冠突及尺桡侧副韧带。     

应用生物力学方法探讨桡骨小头切除术晚期并发症的原因

自１９７８年，共施行桡骨头切除术３７例。２７例获２年以上随访。肘外翻畸形，肘关节慢性不稳定，桡骨干上移和下尺桡关节脱位是主要并发症。作者用２０只新鲜上肥标本进行生物力学实验，发现肘关节内侧副韧带损伤，有间膜撕裂狎和下尺桡关节痈位是引起或加重并发症的主要原因。其中内侧副韧带损伤是最重要的原因。同时，临床上也以桡骨头损伤合并内介副韧带损伤多见。作者强调：桡骨头切除时，应考虑上术三种软组织损伤是否存在及     

桡骨头骨折治疗方法的选择

目的讨论桡骨头骨折的治疗方法及效果。方法2001年1月至2006年1月治疗桡骨头骨折35例，按Manson分Ⅰ型，型9例；Ⅱ型11例，合并肘内侧副韧带损伤3例；Ⅲ型13例，合并肘内侧副韧带损伤5例，Essex—Lopresti损伤1例；Ⅳ型2例，均合并肘内侧副韧带损伤，其中尺骨冠状突骨折1例。Ⅰ型骨折肘关节制动2周后开始功能锻炼；Ⅱ型骨折桡骨头切开复位固定后，检查肘关节伸直位外翻稳定性，早期肘关节功能锻炼；Ⅲ型骨折切开复位或桡骨头切除，石膏固定3周；Ⅳ型骨折先复位肘关节，肘外侧入路切开复位固定桡骨头，合并冠状突骨折者肘前入路切开复位固定，石膏固定3周。结果30例患者得到平均2．1年随访，按照Anderson肘关节屈曲及前臂旋转功能评价标准评价。Ⅰ型7例：优5例，良2例；Ⅱ型9例：优4例，良4例，差1例；Ⅲ型12例：优5例，良2例，可1例，差4例；Ⅳ型2例：可1例，差1例。结论按桡骨头骨折Manson分型，随着损伤级别增加，治疗效果逐渐变差。合并肘内侧副韧带损伤者，术毕检查肘关节伸直位外翻稳定性，不稳定者石膏固定3周，不必切开修复。桡骨头切除适用于Manson型切开复位固定困难者，效果好。     

前臂纵向不稳定的生物力学研究

目的研究前臂纵向不稳定的生物力学机制,为临床诊断及治疗提供可靠的理论依据。方法12具新鲜冷冻尸体上肢标本制成生物力学模型,固定于MTS858型生物材料实验机上加载恒定100N的轴向负荷,测试不同解剖状态对桡骨纵向位移及前臂纵向稳定性的影响。结果单纯切断骨间膜对前臂的纵向稳定性影响甚微。切除桡骨头,前臂的纵向稳定性降低,桡骨向近端移位明显,再切断骨间膜,将使上述改变加重。结论桡骨是维持前臂纵向稳定的主要结构,前臂骨问膜是次要稳定结构。桡骨头切除后骨间膜损伤是前臂纵向不稳定产生并发症的主要原因。     

冠突骨折及合并桡骨小头粉碎骨折生物力学

[目的]分析尺骨冠突骨折及合并桡骨小头粉碎骨折时肘关节的稳定性。[方法]选取上肢尸体标本8对，测试各种冠突骨折及合并桡骨小头粉碎骨折时肘外翻位移及外旋角。[结果]肘关节稳定性在冠突无骨折、Ⅰ型骨折、Ⅱ型骨折各组间无显著差异，冠突Ⅲ型骨折时显著不稳定。[结论]冠突骨折及合并桡骨小头粉碎骨折在冠突Ⅰ型、Ⅱ型骨折时肘关节稳定，可行桡骨小头切除术，Ⅲ型骨折不稳定，应修复桡骨小头或假体置换，并修复桡侧副韧带。     

Essex-Lopresti损伤的生物力学研究

目的 探讨Essex-Lopresti损伤的生物力学机制,为诊治Essex-Lopresti损伤提供生物力学依据.方法 取12具成人新鲜冰冻上肢标本予以处理,先将12具标本("完整状态组")分别在旋前位、旋后位及中立位三种状态下把标本夹持固定于MTS 858生物材料试验机上进行力学测试,恒定加载100 N的压力负荷,每种状态持续30 s后减载.随后将12具标本随机分为2组,6具切除桡骨头为"切头留膜组";另6具切断前臂骨间膜(interosseous membrane,IOM)中间腱性部分为"留头切膜组".每组按上述方法进行生物力学测试.最后将所有标本均切除桡骨头并切断IOM("切头切膜组")按上述方法进行生物力学测试.结果 前臂旋转状态或单纯切断IOM对桡骨纵向位移无影响.单纯切除桡骨头或联合切断IOM和切除桡骨头增加了桡骨的纵向位移.前臂中立位时的桡骨刚度比前臂旋前位大,但比前臂旋后位小.单纯切断IOM对桡骨刚度没有影响,单纯切除桡骨头或联合切断IOM和切除桡骨头则会使桡骨刚度下降.结论 桡骨头骨折合并IOM损伤可能是Essex-Lopresti损伤产生并发症的重要原因,其中桡骨头骨折是Essex-Lopresti损伤主要原因,而IOM损伤是次要原因.桡骨头切除后IOM是维持前臂纵向稳定的主要结构.     

重建肘关节外翻稳定性的生物力学研究

目的　评价肘关节桡骨头 (radial head,RH)切除、尺侧副韧带 (medial collateral ligament,MCL )损伤以及 RH假体置换、MCL重建后的外翻稳定性。　方法　新鲜成人尸体上肢标本 12侧 ,制成肘关节“骨 -韧带”标本 ,在2 N· m的外翻力矩作用下 ,分别在肘关节 0°、30°、6 0°、90°和 12 0°伸屈时 ,测量肘关节外翻松弛度 :1完整肘关节(n=12 ) ;2 MCL切断 (n=6 ) ;3RH切除 (n=6 ) ;4 MCL切断 +RH切除 (n=12 ) ;5 RH假体置换 (n=6 ) ;6 MCL重建(n=6 ) ;7RH假体置换 +MCL重建 (n=12 )。用 SPSS 10 .0统计软件包作方差分析 ,比较各组的外翻稳定性。　结果　完整肘关节的平均外翻松弛度最小 ;RH切除后 ,外翻松弛度增大 ;单纯 MCL切断 ,外翻松弛度大于单纯 RH切除 (P<0 .0 1) ;MCL切断 +RH切除 ,外翻稳定性最差 ;行 RH假体置换 ,对稳定性有改善 ;MCL重建与完整 MCL差异无统计学意义 (P>0 .0 5 ) ;RH假体置换同时重建 MCL ,效果最好。　结论　 MCL是抵抗肘关节外翻应力最主要的因素 ,RH是次要因素。在重建肘关节的外翻稳定性方面 ,MCL的重建比 RH的假体置换更重要。在无条件行 RH假体置换时 ,修复MCL是较好的手术方式。     

桡骨小头切除晚期并发症的原因及机制探讨

目的：研究桡骨小头切除后晚期并发症产生的原因、发病机制和预防措施。方法：对２８例桡骨小头切除术后进行２年以上随访。同时对２０例新鲜上肢标本进行生物力学检测。结果：发现桡骨小头切除术后的晚期并发症有肘外翻畸形、创伤性关节炎、桡尺远侧关节脱位等。肘关节内侧副韧带损伤、骨间膜撕裂伤和桡尺关节远侧脱位是桡骨小头切除术后引起或加重晚期并发症的主要原因。结论：桡骨小头切除时,应考虑上述三种组织损伤是否存在及对预后的影响;桡骨小头切除在青少年患者应视为禁忌     

Metallic radial head arthroplasty improves valgus stability of the elbow

The stabilizing influence of radial head arthroplasty was studied in eight medial collateral ligament deficient anatomic specimen elbows. An elbow testing apparatus, which used computer controlled pneumatic actuators to apply tendon loading, was used to simulate active elbow flexion. The motion pathways of the elbow were measured using an electromagnetic tracking device, with the forearm in supination and pronation. As a measure of stability, the maximum varus to valgus laxity over the range of elbow flexion was determined from the difference between varus and valgus gravity loaded motion pathways. After transection of the medial collateral ligament, the radial head was excised and replaced with either a silicone or one of three metallic radial head prostheses. Medial collateral ligament transection caused a significant increase in the maximum varus to valgus laxity to 18.0 degrees +/- 3.2 degrees. After radial head excision, this laxity increased to 35.6 degrees +/- 10.3 degrees. The silicone implant conferred no increase in elbow stability, with a maximum varus to valgus laxity of 32.5 degrees +/- 15.5 degrees. All three metallic implants improved the valgus stability of the medial collateral ligament deficient elbow, providing stability similar to the intact radial head. The use of silicone arthroplasty to replace the radial head in the medial collateral ligament deficient elbow must be questioned. Metallic radial head arthroplasty provides improved valgus stability, approaching that of an intact radial head.     

Effectiveness of the lateral unilateral dynamic external fixator after elbow ligament injury

BACKGROUND: The optimum management of ligamentous injuries of the elbow is not known. Use of dynamic external fixators has been advocated to stabilize the joint while maintaining motion, but there are no published data to corroborate their efficacy. The purpose of this study was to test the hypothesis that a laterally applied unilateral dynamic external fixator is capable of stabilizing and restoring normal kinematics to elbows with varying degrees of soft-tissue injury. METHODS: Six fresh-frozen cadaveric upper extremities, from donors who were an average of seventy-six years of age at the time of death, were tested in a custom apparatus with an electromagnetic tracking device to analyze the kinematic behavior. Testing began with an injury of either the lateral or the medial collateral ligament, which was followed by a second test with an injury to the ligament on the contralateral side of the joint. In each test, the varus-valgus displacement and the forearm rotatory displacement were measured through the arc of elbow flexion under three loading conditions (hand weight alone, hand weight plus 3.5 N, and hand weight plus 7 N). After each test (with each injury), a unilateral external fixator was applied from the lateral aspect of the elbow, and the same measurements were conducted under the three loading conditions across the elbow joint. RESULTS: With varus stress testing, both after injury of the medial collateral ligament alone and after injury of the lateral collateral ligament and extensor mass alone, the laterally applied unilateral dynamic external fixator was capable of maintaining the displacements within the laxity envelope of an uninjured elbow. With valgus stress testing, after either lateral or medial ligamentous injury, the fixator was unable to maintain displacements within the normal laxity envelope when a 7-N load was applied to the elbow. When both medial and lateral injuries were present, the lateral fixator maintained varus displacement within normal limits, but valgus displacement was consistently maintained within normal limits only when no additional load was applied to the forearm. CONCLUSIONS: A lateral dynamic elbow external fixator is capable of maintaining varus displacements within normal limits in the presence of medial and lateral collateral ligament injuries and with a 7-N load added to the limb. However, valgus displacement is only consistently maintained within normal limits if no additional displacement force is added to the weight of the hand and forearm. The maintenance of valgus displacement is more sensitive to additional load and specifically to the extent of medial soft-tissue injury.     

Contribution of monoblock and bipolar radial head prostheses to valgus stability of the elbow.

BACKGROUND: The purpose of this study was to evaluate the stabilizing effect of radial head replacement in cadaver elbows with a deficient medial collateral ligament. METHODS: Passive elbow flexion with the forearm in neutral rotation and in 80 degrees of pronation and supination was performed under valgus and varus loads (1) in intact elbows, (2) after a surgical approach (lateral epicondylar osteotomy of the distal part of the humerus), (3) after release of the anterior bundle of the medial collateral ligament, (4) after release of the anterior bundle of the medial collateral ligament and resection of the radial head, and (5) after subsequent replacement of the radial head with each of three different types of radial head prostheses (a Wright monoblock titanium implant, a KPS bipolar Vitallium [cobalt-chromium]-polyethylene implant, and a Judet bipolar Vitallium-polyethylene-Vitallium implant) in the same cadaver elbow. Total valgus elbow laxity was quantified with use of an electromagnetic tracking device. RESULTS: The mean valgus laxity changed significantly (p < 0.001) as a factor of constraint alteration. The greatest laxity was observed after release of the medial collateral ligament together with resection of the radial head (11.1 degrees +/- 5.6 degrees). Less laxity was seen following release of the medial collateral ligament alone (6.8 degrees +/- 3.4 degrees), and the least laxity was seen in the intact state (3.4 degrees +/- 1.6 degrees). Forearm rotation had a significant effect (p = 0.003) on valgus laxity throughout the range of flexion. The laxity was always greater in pronation than it was in neutral rotation or in supination. The mean valgus laxity values for the elbows with a deficient medial collateral ligament and an implant were significantly greater than those for the medial collateral ligament-deficient elbows before radial head resection (p < 0.05). The implants all performed similarly except in neutral forearm rotation, in which the elbow laxity associated with the Judet implant was significantly greater than that associated with the other two implants. CONCLUSIONS AND CLINICAL RELEVANCE: This study showed that a bipolar radial head prosthesis can be as effective as a solid monoblock prosthesis in restoring valgus stability in a medial collateral ligament-deficient elbow. However, none of the prostheses functioned as well as the native radial head, suggesting that open reduction and internal fixation to restore radial head anatomy is preferable to replacement when possible.     

Kinematics of partial and total ruptures of the medial collateral ligament of the elbow

In this study the kinematics of partial and total ruptures of the medial collateral ligament of the elbow are investigated. After selective transection of the medial collateral ligament of 8 osteoligamentous intact elbow preparations was performed, 3-dimensional measurements of angular displacement, increase in medial joint opening, and translation of the radial head were examined during application of relevant stress. Increase in joint opening was significant only after complete transection of the anterior part of the medial collateral ligament was performed. The joint opening was detected during valgus and internal rotatory stress only. After partial transection of the anterior bundle of the medial collateral ligament was performed, there was an elbow laxity to valgus and internal rotatory force, which became significant after transection of 100% of the anterior bundle of the medial collateral ligament and was maximum between 70 degrees to 90 degrees of flexion. No radial head movement was seen after partial or total transection of the anterior bundle of the medial collateral ligament was performed. In conclusion, this study indicates that valgus or internal rotatory elbow instability should be evaluated at 70 degrees to 90 degrees of flexion. Detection of partial ruptures in the anterior bundle of the medial collateral ligament based on medial joint opening and increased valgus movement is impossible.     

The effect of radial head fracture size on elbow kinematics and stability.

This study determined the effect of radial head fracture size and ligament injury on elbow kinematics. Eight cadaveric upper extremities were studied in an in vitro elbow simulator. Testing was performed with ligaments intact, with the medial collateral (MCL) or lateral collateral (LCL) ligament detached, and with both the MCL and LCL detached. Thirty degree wedges were sequentially removed from the anterolateral radial head up to 120 degrees . Valgus angulation and external rotation of the ulna relative to the humerus were determined for passive motion, active motion, and pivot shift testing with the arm in a vertical (dependent) orientation. Maximum varus-valgus laxity was calculated from measurements of varus and valgus angulation with the arm in horizontal gravity-loaded positions. No effect of increasing radial head fracture size was observed on valgus angulation during passive and active motion in the dependent position. In supination, external rotation increased with increasing fracture size during passive motion with LCL deficiency and both MCL and LCL deficiency. With intact ligaments, maximum varus-valgus laxity increased with increasing radial head fracture size. With ligament disruption, elbows were grossly unstable, and no effect of increasing radial head fracture size occurred. During pivot shift testing, performed with the ligaments intact, subtle instability was noted after resection of one-third of the radial head. In this in vitro biomechanical study, small subtle effects of radial head fracture size on elbow kinematics and stability were seen in both the ligament intact and ligament deficient elbows. These data suggest that fixation of displaced radial head fractures less than or equal to one-third of the articular diameter may have some biomechanical advantages; however, clinical correlation is required.     

Valgus stability of the elbow. A definition of primary and secondary constraints

The stabilizing structures of the elbow that resist valgus stress were studied with a tracking device in a model simulating active motion and muscle activity. By varying the order of serial release of the medial collateral ligament complex and removal of the radial head, each structure's contribution to valgus stability against the effect of gravity was determined. In the otherwise intact elbow, absence of the radial head does not significantly alter the three-dimensional characteristics of motion in the elbow joint. Isolated medial collateral release, on the other hand, causes increases in abduction rotation of about 6 degrees-8 degrees in magnitude. Releasing both structures results in gross abduction laxity and elbow subluxation. This study defines the medial collateral ligament (MCL) as the primary constraint of the elbow joint to valgus stress and the radial head as a secondary constraint. This definition facilitates the proper management of patients with radial head fractures and MCL disruption. The comminuted radial head fracture uncomplicated by MCL insufficiency should be treated by excision without the need for an implant and without concern of altering the normal kinematics of the elbow.     

Radial head fracture in the medial collateral ligament deficient elbow; biomechanical comparison of fixation, replacement and excision in human cadavers

A widely used clinical recommendation is that in the presence of medial collateral ligament injuries, two-part radial head fractures should be fixed rather than excising or replacing the radial head. Direct biomechanical data comparing fracture fixation, radial head replacement and excision in a human cadaveric elbow model, have not been previously described. Such comparison is clinically important as with the increasing availability of radial head implants and promising follow up results, the role of radial head replacement in fracture management may have to be redefined. In this study, five fresh cadaveric elbows had radial head fracture creation and medial collateral ligament division, fracture fixation, radial head replacement and excision. Valgus and varus laxity were determined using an electromagnetic tracking system. Radial head replacement leads to a similar valgus (P=0.80) [corrected] laxity as compared to radial head fixation. Radial head excision resulted in a significantly greater valgus laxity as compared to radial head fixation (P=0.02) or replacement (P=0.03). Both radial head excision and replacement led to a greater varus laxity as compared to fixation. Our results suggest that in the elbow with medial collateral ligament injury and two-part radial head fracture, fixation is overall biomechanically superior as compared to replacement and excision.     

Biomechanical evaluation of the elbow using roentgen stereophotogrammetric analysis

The medial collateral ligament complex is the primary constraint of the elbow to valgus forces and is composed of the anterior bundle, the posterior bundle, and a transverse part. Total and partial ruptures have been described. Clinical and radiologic examinations of medial or valgus instability of the elbow are difficult. The effect of different stages of medial collateral ligament ruptures on ulnohumeral movement in cadavers was determined to rationalize the use of physical and radiologic examinations in different stages of valgus instability in vivo. Using roentgen stereophotogrammetric analysis, motion is determined between the humerus and ulna under valgus load and between the humerus and radius during maximal pronation of the forearm after various dimensions of medial collateral ligament lesions. The increase in distance between the humerus and ulna under a 15 N valgus load varied from 2.7 mm to 9.8 mm. The increase in distance between the humerus and proximal radius with the forearm in pronation in an intact specimen and after transsection of the anterior medial collateral ligament and posterior medial collateral ligament in the anterior direction was 9.7 mm. These results suggest that detection of partial ruptures with clinical and radiologic examinations is difficult. Anterior movement of the radial head can be used as an additional parameter of valgus instability.