Kinematics of the ligamentous unstable elbow joint after application of a hinged external fixation device: a cadaveric study

We studied the kinematics of 8 ligamentous unstable elbow joint preparations after application of the Orthofix elbow external fixation device. Valgus, varus, external rotatory, and internal rotatory load tests were performed in lateral collateral ligament (LCL)-deficient and LCL/medial collateral ligament (MCL)-deficient joints. After placement of the fixator, the mean extension decreased significantly to 19.5 degrees +/- 7.2 degrees in the LCL-deficient joint and to 19.1 degrees +/- 6.6 degrees in the LCL/MCL-deficient joint compared with the mean extension of the intact joint, which was 10.5 degrees +/- 4.2 degrees. After application of the fixator, valgus displacement was significantly decreased by 4.0 degrees +/- 3.4 degrees in the LCL-deficient joint and by 3.6 degrees +/- 3.3 degrees in the LCL/MCL-deficient joint compared with the intact joint. External rotatory displacement was significantly decreased in the LCL-deficient joint by 4.9 degrees +/- 3.7 degrees and in the LCL/MCL-deficient joint by 5.0 degrees +/- 4.7 degrees. Internal rotatory displacement was significantly decreased by 3.3 degrees +/- 2.7 degrees in the LCL-deficient joint, but it was not significantly changed in the LCL/MCL-deficient joint. The Orthofix elbow external fixator guided elbow motion to a more varus position compared with the intact elbow and decreased the range of motion of the joint, constraining mainly extension. We conclude that the fixator stabilized the ligamentous unstable elbow joint efficiently but at the expense of changes in the normal motion pattern.     

Dislocation of the elbow: an experimental study of the ligamentous injuries

The stability of human cadaveric elbow specimens was investigated using an experimental apparatus. Posterior dislocation of the elbow could only be produced when a combined valgus and external rotatory torque was applied to the specimen. None of the elbows were dislocated during varus and internal rotatory torque or in the extreme positions. In ten elbow specimens with an experimentally produced posterior dislocation, simultaneous rupture of the anterior part of the medial collateral ligament and the annular ligament were the most frequent findings. A lateral collateral ligament tear was only seen in two cases. Posterior elbow dislocation seems to be due to a combined valgus and external rotatory stress to the semiflexed elbow, resulting in a bilateral ligamentous injury.     

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.     

桡骨头切除对肘关节稳定性影响的生物力学研究

目的：探讨桡骨头粉碎性骨折不同治疗方法对肘关节稳定性的影响。方法：将10个尸体标本，分别测定在其它组织无损伤时，肘内侧副韧带切断时，肘内侧副韧带和前臂骨间膜均切断时的力－位移曲线（纵向位移）及肘外翻角。结果：肘内侧副韧带切断时的纵向位移及肘外翻角均大于其它组织无损伤时；肘内侧副韧带和前臂骨间膜均切断时的纵向位移及肘外翻角均大于其它组织无损伤时和肘内侧副韧带切断时，两两间比较均有显著性差异（P＜0．001）。结论：在其它组织无损伤时，单纯桡骨头切除是安全的；合并肘内侧副韧带损伤时，可在有效修补韧带的同时作单纯头切除，必要时行假体置换；合并肘内侧副韧带和前臂骨间膜均损伤时，最好作假体置换。     

尺骨鹰嘴部分切除对肘关节稳定性影响的研究

目的探讨尺骨鹰嘴尖部截骨短缩对肘关节稳定性的影响。方法取10具20侧男性新鲜上肢标本，随机分为四组，每组5侧标本，即尺骨鹰嘴完整组、截骨3mm组、截骨6mm组、截骨9mm组，截骨在尺骨鹰嘴尖部。每组分别在肘关节屈曲30°、60°、90°、120°时，前臂加1．96Nm力矩的情况下，测量外翻位肘外翻角度和内侧副韧带前束长度及内翻位肘内翻角度和桡侧尺副韧带长度。结果尺骨鹰嘴尖部截骨时，于同一肘关节屈曲位，随着尺骨鹰嘴尖部截骨量增大，肘关节内侧副韧带前束的长度逐渐变长，外翻角逐渐增大，当截骨量大于3mm上述变化差异显著，有统计学意义（P〈0．05）。结论尺骨鹰嘴尖部截骨量超过3mm时，肘关节出现不稳定。因此临床上当尺骨鹰嘴尖部严重粉碎性骨折片不超过3mm时，可予以手术切除，对肘关节稳定性影响不大，否则应给予修复重建。而对于尺骨鹰嘴尖部后内侧骨赘，建议仅切除骨赘或切除范围不超过正常鹰嘴尖部3mm。     

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.     

Medial collateral ligament injury in the overhand-throwing athlete

Medial collateral ligament injuries are rare and occur almost exclusively in overhand-throwing athletes. The late cocking phase of the overhand throw places a marked valgus moment across the medial elbow. This repetitive force reaches the tensile limits of the medial collateral ligament, subjecting it to microtraumatic injury and attenuation. The anterior bundle of the medial collateral ligament has been identified as the primary restraint to valgus load and is the focus of reconstruction. Diagnosis of medial collateral ligament injuries should be suspected in any overhand-throwing athlete with a history of medial-sided elbow pain, decreased control, and reduced throwing velocity. Injury to the medial collateral ligament can be confirmed by physical examination (moving valgus stress test) and appropriate imaging studies (computed tomography arthrogram and magnetic resonance imaging). Reconstructive techniques of the medial collateral ligament have evolved over time and currently provide superior outcomes, with 80% to 90% of athletes returning to the same level of competitive play. As our understanding of the pathoanatomy of medial elbow injuries progresses and newer hybrid techniques evolve, our ability to care for the overhand-throwing athlete can be expected to improve.     

Acute elbow injuries in the National Football League

We performed a retrospective review to evaluate acute medial collateral ligament injuries of the elbow in professional football players from 1991 to 1996 (5 seasons). There were 5 acute medial collateral ligament injuries in 4 players (1 player with bilateral involvement). All injuries occurred with the hand planted on the playing surface while a valgus or hyperextension force was applied to the elbow. There were 2 centers, both involved with long-snapping situations, 1 running back, and 1 quarterback. All elbows had valgus instability on physical examination. Despite this instability, all players were able to function without operative reconstruction of the medial collateral ligament. No evidence of valgus instability was seen at the time of follow-up (average, 3.4 years). Next, we reviewed all acute elbow injuries in the National Football League from the same 5-season period. Ninety-one acute elbow injuries were reviewed. Overall, there were 70 (76.9%) elbow sprains, 16 (17.6%) dislocation/subluxation patterns, 4 (4.4%) fractures, and 1 (1.1%) miscellaneous injury. Review of the acute elbow sprains revealed 39 (55.7%) hyperextension injuries, 14 (20%) medial collateral ligament injuries, 2 (2.9%) lateral collateral ligament sprains, and 15 (21.4%) nonspecific sprains. The epidemiology of the 14 medial collateral ligament injuries was studied in more detail. The 2 most common mechanisms of injury were blocking at the line of scrimmage (50%) and the application of a valgus force with the hand planted on the playing surface (29%). There were 8 linemen, 4 receivers, 1 running back, and 1 quarterback. All injuries were managed with nonoperative treatment. The average time lost was 0.64 games (range, 0 to 4). We report 19 acute medial collateral ligament injuries of the elbow in elite football players, 2 of whom are considered overhead throwing athletes, who were able to function at a competitive level without surgical repair or reconstruction, in contrast to baseball players, in whom the mechanics and demands may differ.     

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.     

Capitellum excision: Mechanical implications and clinical consequences

Controversy exists regarding the optimal treatment of isolated fractures of the capitellum that are not amenable to open reduction and internal fixation. Excision of the capitellum could result in instability of the elbow, though only limited the clinical or laboratory evidence exists to support this outcome. The aim of our study was to determine if capitellum excision leads to significant instability by measuring the relative change in varus–valgus displacement of the elbow. The varus–valgus displacement was recorded in 11 cadaveric elbows before and after isolated excision of the capitellum. Specimens were testing in varus‐loaded and valgus‐loaded positions with and without a 1 kg weight on the forearm. The varus–valgus displacement at the elbow was measured using a 3D motion capture system. Capitellum excision did not significantly change varus–valgus displacements in either the adducted, varus, or valgus position of the elbow (p = 0.80, p = 0.28, p = 0.51). Furthermore, the addition of the 1 kg external functional load to the forearm did not produce a significant change in the varus and valgus loaded positions (p = 0.16, p = 0.36). Our results demonstrate that excision of the capitellum in the setting of intact ligamentous structures does not result in significant instability in either the adducted varus loaded or valgus loaded positions of the elbow. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:346–350, 2014.     

Diagnostik und Therapie der ligamentären Ellenbogeninstabilitäten

Posttraumatic or acute instability of the elbow can develop after complete or incomplete dislocation of the elbow. Isolated medial collateral ligament ruptures can be a result of valgus trauma and lateral collateral ligament ruptures of pivot shift or varus trauma. Chronic instability of the elbow may occur after conservative or operative treatment of a traumatic ligament rupture without stable healing. Repetitive overuse in sports or professions may also cause chronic instability. This article provides the reader an overview about current concepts in elbow instability.     

Instabilitätsrelevante Anatomie des Ellenbogens

Background

Detailed knowledge of elbow anatomy is crucial for diagnosis and therapy of instabilities around the elbow joint.

Discussion

Several anatomical structures stabilize the elbow joint. Due to its high congruency, the ulnohumeral joint protects the joint especially against varus as well as valgus stress and distraction particularly in full extension. The radiohumeral joint and proximal radioulnar joint are secondary stabilizers against valgus stress. The primary stabilizer against valgus stress is the medial collateral ligament which can be divided into an anterior and a posterior bundle. The lateral collateral ligament consists of the radial collateral ligament, the lateral ulnar collateral ligament and the annular ligament. The lateral collateral ligament in its entirety stabilizes the elbow against varus forces and posterolateral rotatory instability.

Conclusion

In addition, muscles spanning over the elbow joint are dynamic and static stabilizers via joint compression forces of the muscles and the orientation of muscle fibers that resemble those of the collateral ligaments.

     

Muscle forces and pronation stabilize the lateral ligament deficient elbow.

The influence of muscle activity and forearm position on the stability of the lateral collateral ligament deficient elbow was investigated in vitro, using a custom testing apparatus to simulate active and passive elbow flexion. Rotation of the ulna relative to the humerus was measured before and after sectioning of the joint capsule, and the radial and lateral ulnar collateral ligaments from the lateral epicondyle. Gross instability was present after lateral collateral ligament transection during passive elbow flexion with the arm in the varus orientation. In the vertical orientation during passive elbow flexion, stability of the lateral collateral ligament deficient elbow was similar to the intact elbow with the forearm held in pronation, but not similar to the intact elbow when maintained in supination. This instability with the forearm supinated was reduced significantly when simulated active flexion was done. The stabilizing effect of muscle activity suggests physical therapy of the lateral collateral ligament deficient elbow should focus on active rather than passive mobilization, while avoiding shoulder abduction to minimize varus elbow stress. Passive mobilization should be done with the forearm maintained in pronation.     

冠突前内侧面骨折与外侧副韧带损伤的治疗

目的探讨冠突前内侧骨折后,外侧副韧带是否需要全部修复。 方法选自2012年7月至2016年7月天津医院共收治的19例冠突前内侧骨折患者,排除1例合并桡骨远端骨折患者,1例既往关节炎患者。术前行影像学检查,包括肘关节正侧位X线片、CT检查,以明确损伤类型。根据O’Driscoll分型2-1型4例,2-2型9例,2-3型4例。所有患者均采用肘关节内侧入路（尺侧腕屈肌入路）,固定冠突骨折后,给予内翻应力试验,如为阳性,修复外侧副韧带;如为阴性,不修复。采用Mayo肘关节功能评分（mayo elbow performance score,MEPS）、上肢功能障碍评分（disability of arm shoulder and hand,DASH）、视觉模拟评分法（visual analogue scale/score,VAS）对肘关节功能进行评价。 结果冠突骨折固定后,内翻试验阳性患者13例,给予外侧副韧带修补术,阴性患者4例,未给予外侧副韧带修补。所有患者均获得满意的肘关节评分,MEPS平均97.6分,DASH平均4.13分,VAS平均0.4分;关节炎Broberg-Morrey标准I度5例。 结论在冠突前内侧骨折的治疗中,冠突固定后的内翻试验对于判断肘关节稳定性至关重要,外侧副韧带修复与否取决于内翻应力试验。     

Strain in the human medial collateral ligament during valgus loading of the knee

The medial collateral ligament is one of the most frequently injured ligaments in the knee. Although the medial collateral ligament is known to provide a primary restraint to valgus and external rotations, details regarding its precise mechanical function are unknown. In this study, strain in the medial collateral ligament of eight knees from male cadavers was measured during valgus loading. A material testing machine was used to apply 10 cycles of varus and valgus rotation to limits of +/- 10.0 N-m at flexion angles of 0 degrees, 30 degrees, 60 degrees, and 90 degrees. A three-dimensional motion analysis system measured local tissue strain on the medial collateral ligament surface within 12 regions encompassing nearly the entire medial collateral ligament surface. Results indicated that strain is significantly different in different regions over the surface of the medial collateral ligament and that this distribution of strain changes with flexion angle and with the application of a valgus torque. Strain in the posterior and central portions of the medial collateral ligament generally decreased with increasing flexion angle, whereas strain in the anterior fibers remained relatively constant with changes in flexion angle. The highest strains in the medial collateral ligament were found at full extension on the posterior side of the medial collateral ligament near the femoral insertion. These data support clinical findings that suggest the femoral insertion is the most common location for medial collateral ligament injuries.     

Medial instability of the elbow: Findings on valgus load radiography and MRI in 16 athletes

Medial discomfort of the elbow in athletes can be due to valgus instability after acute ligament rupture or attenuation of the medial collateral ligament caused by repetitive microtrauma during overhead throwing. We studied 16 athletes with medial instability of the elbow due to insufficiency of the medial collateral ligament. 4 patients had sensory ulnar nerve symptoms, of whom 2 had abnormalities of the ulnar nerve on electromyography. 13 showed an increase in the ulno-humeral joint space on dynamic radiography under valgus load. MRI of 10 of these 13 elbows revealed rupture of the medial collateral ligament or avulsion of the medial collateral ligament. Dynamic radiography under valgus load seems to be of value for the diagnosis of chronic medial collateral ligament insufficiency.     

Medial instability of the elbow: findings on valgus load radiography and MRI in 16 athletes

Medial discomfort of the elbow in athletes can be due to valgus instability after acute ligament rupture or attenuation of the medial collateral ligament caused by repetitive microtrauma during overhead throwing. We studied 16 athletes with medial instability of the elbow due to insufficiency of the medial collateral ligament. 4 patients had sensory ulnar nerve symptoms, of whom 2 had abnormalities of the ulnar nerve on electromyography. 13 showed an increase in the ulno-humeral joint space on dynamic radiography under valgus load. MRI of 10 of these 13 elbows revealed rupture of the medial collateral ligament or avulsion of the medial collateral ligament. Dynamic radiography under valgus load seems to be of value for the diagnosis of chronic medial collateral ligament insufficiency.     

Ligamentous reconstruction around the elbow using triceps tendon

Posttraumatic instability of the elbow joint can be osseous or ligamentous. Ligamentous instability can be in valgus or in posterolateral rotatory direction. Rupture of both the lateral and medial collateral ligament of the elbow can be seen as an isolated injury, or it can be part of a more complex injury such as a dislocation. Persistent insufficiency of the lateral collateral ligament of the elbow results in posterolateral rotatory instability. Insufficiency of the medial collateral ligament, the anterior part in particular, results in valgus instability. Persistent symptoms after nonoperative treatment are an indication for reconstruction. In the past, ligamentous reconstruction at both the lateral and medial side was performed using palmaris tendon graft through bony drill holes. In this article I describe a new technique using ipsilateral triceps tendon, fixed in drill holes using bioabsorbable interference screws. This technique allows simplified graft tensioning and improved graft fixation, and avoids the risk of fracturing of the bony tunnels. An accelerated rehabilitation protocol can be applied. The final result depends on proper isometric reconstruction, associated lesions or degeneration of the elbow joint and adequate after-treatment. Taking these factors into account, the technique described shows promising short-term results.     

Medial instability of the elbow: Findings on valgus load radiography and MRI in 16 athletes

Medial discomfort of the elbow in athletes can be due to valgus instability after acute ligament rupture or attenuation of the medial collateral ligament caused by repetitive microtrauma during overhead throwing. We studied 16 athletes with medial instability of the elbow due to insufficiency of the medial collateral ligament. 4 patients had sensory ulnar nerve symptoms, of whom 2 had abnormalities of the ulnar nerve on electromyography. 13 showed an increase in the ulno-humeral joint space on dynamic radiography under valgus load. MRI of 10 of these 13 elbows revealed rupture of the medial collateral ligament or avulsion of the medial collateral ligament. Dynamic radiography under valgus load seems to be of value for the diagnosis of chronic medial collateral ligament insufficiency.     

Effects of elbow flexion and forearm rotation on valgus laxity of the elbow

BACKGROUND: Clinical evaluation of valgus elbow laxity is difficult. The optimum position of elbow flexion and forearm rotation with which to identify valgus laxity in a patient with an injury of the ulnar collateral ligament of the elbow has not been determined. The purpose of the present study was to determine the effect of forearm rotation and elbow flexion on valgus elbow laxity. METHODS: Twelve intact cadaveric upper extremities were studied with a custom elbow-testing device. Laxity was measured with the forearm in pronation, supination, and neutral rotation at 30 degrees, 50 degrees, and 70 degrees of elbow flexion with use of 2 Nm of valgus torque. Testing was conducted with the ulnar collateral ligament intact, with the joint vented, after cutting of the anterior half (six specimens) or posterior half (six specimens) of the anterior oblique ligament of the ulnar collateral ligament, and after complete sectioning of the anterior oblique ligament. Laxity was measured in degrees of valgus angulation in different positions of elbow flexion and forearm rotation. RESULTS: There were no significant differences in valgus laxity with respect to elbow flexion within each condition. Overall, for both groups of specimens (i.e., specimens in which the anterior or posterior half of the anterior oblique ligament was cut), neutral forearm rotation resulted in greater valgus laxity than pronation or supination did (p < 0.05). Transection of the anterior half of the anterior oblique ligament did not significantly increase valgus laxity; however, transection of the posterior half resulted in increased valgus laxity in some positions. Full transection of the anterior oblique ligament significantly increased valgus laxity in all positions (p < 0.05). CONCLUSIONS: The results of this in vitro cadaveric study demonstrated that forearm rotation had a significant effect on varus-valgus laxity. Laxity was always greatest in neutral forearm rotation throughout the ranges of elbow flexion and the various surgical conditions. CLINICAL RELEVANCE: The information obtained from the present study suggests that forearm rotation affects varus-valgus elbow laxity. Additional investigation is warranted to determine if forearm rotation should be considered in the evaluation and treatment of ulnar collateral ligament injuries of the elbow joint.