The "moving valgus stress test" for medial collateral ligament tears of the elbow

BACKGROUND: The diagnosis of a painful partial tear of the medial collateral ligament in overhead-throwing athletes is challenging, even for experienced elbow surgeons and despite the use of sophisticated imaging techniques. HYPOTHESIS: The "moving valgus stress test" is an accurate physical examination technique for diagnosis of medial collateral ligament attenuation in the elbow. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: Twenty-one patients underwent surgical intervention for medial elbow pain due to medial collateral ligament insufficiency or other abnormality of chronic valgus overload, and they were assessed preoperatively with an examination called the moving valgus stress test. To perform the moving valgus stress test, the examiner applies and maintains a constant moderate valgus torque to the fully flexed elbow and then quickly extends the elbow. The test is positive if the medial elbow pain is reproduced at the medial collateral ligament and is at maximum between 120 degrees and 70 degrees. RESULTS: The moving valgus stress test was highly sensitive (100%, 17 of 17 patients) and specific (75%, 3 of 4 patients) when compared to assessment of the medial collateral ligament by surgical exploration or arthroscopic valgus stress testing. The mean shear range (ie, the arc within which pain was produced with the moving valgus stress test) was 120 degrees to 70 degrees. The mean angle at which pain was at a maximum was 90 degrees of elbow flexion. CONCLUSIONS: The moving valgus stress test is an accurate physical examination technique that, when performed and interpreted correctly, is highly sensitive for medial elbow pain arising from the medial collateral ligament.     

Anterior bundle of ulnar collateral ligament: evaluation of anatomic relationships by using MR imaging, MR arthrography, and gross anatomic and histologic analysis

PURPOSE: To evaluate the gross and microscopic anatomy and the magnetic resonance (MR) imaging and MR arthrographic appearance of the anterior bundle of the ulnar collateral ligament (UCL) of the elbow. MATERIALS AND METHODS: The origin and insertion of the anterior bundle of the UCL, the bundle's relationship to the overlying flexor tendons, and the presence of a layered configuration were assessed through inspection and dissection of an elbow specimen. T1-weighted spin-echo MR imaging and MR arthrography in standard imaging planes and a coronal oblique plane were performed in eight other elbow specimens. Additional MR arthrography was performed in four specimens by using the coronal plane with the elbow in 20 degrees of flexion. The specimens were then cut in planes corresponding to those of the MR images. Histologic analysis of two specimens was performed. RESULTS: The anterior bundle of the UCL appeared as a low-signal-intensity structure on T1-weighted spin-echo MR and MR arthrographic images. It consisted of a uniform layer of parallel collagen fibers attaching proximally to the base of the medial epicondyle of the humerus and distally to the medial aspect of the coronoid process of the ulna (sublime tubercle). A layer of synovium separated the anterior bundle from the more superficial tendon of the flexor digitorum superficialis muscle. MR imaging-anatomic comparison in four (50%) specimens revealed separation between the anterior bundle of the UCL and the sublime tubercle. Results of histologic analysis of two of these specimens confirmed insertion of the anterior bundle of the UCL 3 and 4 mm distal to the articular margin. Ligamentous degeneration was detected in only one of these specimens. CONCLUSION: There is variability in the distal insertion of the anterior bundle, and this suggests that caution should be exercised in the diagnosis of its partial detachment from the sublime tubercle of the ulna.     

Biomechanical evaluation of a new ulnar collateral ligament reconstruction technique with interference screw fixation

BACKGROUND: Techniques for ulnar collateral ligament reconstruction have evolved. HYPOTHESIS: Ulnar collateral ligament reconstruction with interference screw fixation restores elbow kinematics and failure strength to that of the native ligament. STUDY DESIGN: Controlled laboratory study. METHODS: Of 10 matched pairs of cadaveric elbows, one underwent kinematic testing under conditions of an intact, released, and reconstructed ligament. Single 5-mm diameter bone tunnels were created at the isometric anatomic insertion sites on the medial epicondyle and sublime tubercle. Graft fixation was achieved with 5 x 15 mm soft tissue interference screws. The reconstructed and contralateral intact elbows were then tested to failure. RESULTS: Average stiffness for intact elbows (42.81 +/- 11.6 N/mm) was significantly greater than for reconstructed elbows (20.28 +/- 12.5 N/mm). Ultimate moment for intact elbows (34.0 +/- 6.9 N.m) was not significantly different from reconstructed elbows (30.6 +/- 19.2 N.m). Release of the ulnar collateral ligament caused a significant increase in valgus instability. Reconstruction restored valgus stability to near that of the intact elbow. CONCLUSIONS: With this reconstruction method, failure strength was comparable with that of the native ligament and physiologic elbow kinematics were reliably restored. Clinical Relevance: This technique returns elbow kinematics to near normal, with less soft tissue dissection and risk of ulnar nerve injury and ease of graft insertion, tensioning, and fixation.     

Posterior cruciate ligament (PCL) reconstruction-an in vitro study of isometry

Isometric positioning of the posterior cruciate ligament (PCL) graft is important for successful reconstruction of the PCL-deficient knee. This study documents the relationship between graft placement and changes in intra-articular graft length during a passive range of motion of the knee. In eight cadaveric knees the PCL was identified and cut. The specimens were mounted in a stabilising rig. PCL reconstruction was performed using a 9-mm-thick synthetic cord passed through tunnels 10 mm in diameter. Three different femoral graft placement sites were evaluated: (1) in four specimens the tunnel was located around the femoral isometric point, (2) in two specimens the tunnel was positioned over the guide wire 5 mm anterior to the femoral isometric point, (3) in two specimens the tunnel was positioned over the guide wire 5 mm posterior to the isometric femoral point. In all knees only one tibial tunnel was created around the isometric tibial point. The location of the isometric points is described in part I of this study. The proximal end of the cord was fixed to the lateral aspect of the femur. Distally, the cord was attached to a measuring unit. The knees were flexed from 0° to 110°, and the changes in the graft distance between the femoral attachment sites were measured in 10° steps. Over the entire range of motion measured, the femoral tunnels positioned around the isometric point produced femorotibial distance changes of within 2 mm. The anteriorly and posteriorly placed tunnels produced considerable changes in femorotibial distance with knee flexion, e.g. about 8 mm at 110° of flexion.     

运动员肘关节尺侧肌肉韧带断裂与肘内侧不稳(附33例分析)

文章指出,运动员肘尺侧肌肉韧带装置断裂伤,若急性期内处理不当,可致肘关节尺侧不稳而发生肘习惯性外翻脱臼。作者介绍了治疗习惯性外翻脱臼的手术方法效果较好。     

Factors affecting the region of most isometric femoral attachments. Part II: The anterior cruciate ligament

During flexion of the intact knee, we measured the changes in distance between possible tibial and femoral attachments of an intraarticular ACL substitute. The change in distance during motion was described by the difference between the longest and shortest distances measured. Using knees from eight cadaver donors, we studied the effects of varying tibial and femoral attachment locations, applying anterior and posterior forces, and altering the range of flexion. We found that altering the femoral attachment had a much larger effect than had altering the tibial attachment. No femoral attachments were completely isometric. Femoral attachments that produced the smallest change in tibiofemoral distance, 2 mm and less, formed a band whose greatest width ranged from 3 to 5 mm. The axis of the 2 mm region was nearly proximal-distal in orientation and located near the center of the ACL's femoral insertion. Attachments located anterior to the axis moved away from the tibial attachment with flexion, whereas attachments located posterior to the axis moved toward the tibia. The AP position of the tibial attachment affected the orientation of the 2 mm region. Moving the tibial attachment posteriorly caused the proximal part of the region to move anterior, with little change in the location of the distal part of the region. Changing the applied joint force from anterior to posterior was similar to moving the tibial attachment posteriorly, but the effect was less pronounced. Increasing the range of flexion from 90 degrees to 120 degrees caused the 2 mm region to become narrower and changed its orientation.     

A clinical and roentgenographic study of Little League elbow

BACKGROUND: Comparisons of medial elbow injury rate and the incidence of clinical and radiographic findings among Little League baseball players have not been documented. HYPOTHESIS: Injury rate and clinical and radiographic findings in Little Leaguers of different positions may be similar. STUDY DESIGN: Survey and retrospective review. METHODS: Altogether, 343 Little Leaguers (120 pitchers, 40 catchers, and 183 fielders) participated in the study. The survey (including age, playing position, playing experience, and symptoms), clinical examination, and roentgenogram of both elbows were obtained for analysis using Pearson's chi-square test. RESULTS: Clinically, 58% of the pitchers presented with soreness compared to 63% in catchers and 47% in fielders. Radiographic examination revealed hypertrophy of the medial humeral epicondyle in all pitchers and catchers and 90% of the fielders. Separation of the medial epicondyle was found in 63% of pitchers, 70% of catchers, and 50% of fielders, while fragmentation was found in 19% of pitchers, 40% of catchers, and 15% of fielders. In subjects with separation or fragmentation, 49% and 56% complained of elbow soreness, respectively. CONCLUSION: Similar rates of medial elbow changes in Little Leaguers may imply that the roentgenological changes of the medial epicondyle could be an adaptive yet physiological reaction to the excessive valgus stress of throwing. The higher incidence of medial epicondylar separation and fragmentation in catchers that has not been reported before may be secondary to the increased stress placed on the elbow when throwing from the squatting position.     

膝关节内侧副韧带浅层(sMCL)止点的解剖学及有限元分析

目的:探究膝关节内侧副韧带浅层止点的位置、形态及大小,同时利用有限元软件分析内侧副韧带浅层的力学止点分布,从而为临床手术治疗内侧副韧带损伤提供解剖依据。方法:新鲜成人膝关节标本10例,沿膝关节内侧逐层切开,暴露内侧副韧带浅层,沿纤维走形确定内侧副韧带浅层的股骨及胫骨止点,标记止点并切断,测量止点与周围解剖标志的距离以及止点的长度和面积。利用三维薄层核磁共振及三维重建软件MIMICS建立膝关节三维模型,通过有限元分析软件ANSYS模拟侧翻应力试验,观察内侧副韧带浅层的应力分布情况。结果:内侧副韧带浅层的股骨止点近似一椭圆形,位于股骨内上髁后上方,距离内上髁距离为6.82±0.64 mm,平均止点面积为61.64±7.02 mm^2。内侧副韧带浅层的胫骨止点近似一矩形,其中心点距离关节线距离为60.02±0.55 mm,长28.69±4.13 mm,宽8.99±0.62 mm,长宽比为3.19︰1,止点面积为217.78±50.32 mm^2。有限元分析显示,sMCL股骨端应力较高区域靠近内上髁,胫骨端应力较高区域位于胫骨嵴上,与其解剖止点位置基本相符。其中胫骨端应力最大处位于sMCL胫骨止点的最近端。结论:解剖学结果定性及定量描述了sMCL股骨止点与胫骨止点的形状、位置、大小及与周围解剖标志的距离。有限元结果显示sMCL止点的应力与其止点形状及位置基本相符。在临床进行内侧副韧带浅层重建时,应依据其解剖特性及生物力学止点进行解剖重建,以期达到最好的临床效果。     

Elbow medial ulnar collateral ligament insufficiency alters posteromedial olecranon contact

BACKGROUND: The effect of elbow medial ulnar collateral ligament injury on posteromedial compartment contact is unknown. HYPOTHESIS: Medial ulnar collateral ligament injury causes altered contact area and pressure in the posteromedial compartment of the elbow. STUDY DESIGN: Controlled laboratory study. METHODS: Seven elbow cadaveric specimens were tested in an apparatus that positioned the elbow at 30 degrees and 90 degrees of flexion. Partial and full tears were simulated by releasing the medial ulnar collateral ligament. Pressure-sensitive film was placed in the posteromedial compartment for each condition. Valgus torques of 1.25 and 2.0 N.m were applied for each ligament condition, and kinematic data were obtained at each flexion angle using a 3-dimensional digitizer. RESULTS: Both ligament condition and valgus load had significant effects on contact area and pressure (P<.05). For a given load and flexion angle, the contact area decreased and the pressure increased with increasing medial ulnar collateral ligament insufficiency. Within these trends, statistical significance was found at 30 degrees of elbow flexion for both area and pressure (P<.05); at 90 degrees of elbow flexion, increasing medial ulnar collateral ligament insufficiency did not significantly affect contact area or pressure (P>.05). DISCUSSION: Medial ulnar collateral ligament insufficiency alters contact area and pressure between the posteromedial trochlea and olecranon and helps explain the development of posteromedial osteophytes.     

A comparative study of 'isometric' points for anterior cruciate ligament graft attachment

Anterior cruciate ligament (ACL) reconstruction depends critically on isometric graft placement. Unfortunately, different supposedly isometric points have been published, and no prior work has compared them to find out which are really isometric. The purpose of this study was to compare the isometry of previously published 'isometric' points for ACL reconstruction. The isometric points and knee loadings of previous studies were reproduced accurately in 12 fresh cadaveric knees. The length changes were measured through 140 degrees knee flexion, using an intra-articular suture attached to a displacement transducer. Six points had less than 1 mm length change and were located proximally in the natural ACL attachment at the posterior end of Blumensaat's line. The other seven points had length change patterns that would cause ACL graft tightening or slackening with knee flexion if they were used as the sites of bone tunnels for graft placement. This study confirms the existence of an isometric zone close to the posterior end of Blumensaat's line under several loading conditions. Other graft attachment points are less suitable for ACL reconstruction.     

The effect of tibial attachment site on graft impingement in an anterior cruciate ligament reconstruction.

Anterior cruciate ligament reconstructions were performed in 14 cadaveric knee specimens using a 6-mm wide polypropylene graft. The graft was passed through a femoral tunnel at the attachment site of the anterior medial bundle of the anterior cruciate ligament. Seven tibial positions were evaluated as to the change in attachment site distance with passive range of motion and impingement on the intercondylar notch as the knee was passively ranged from 0 degree to 90 degrees of flexion. Impingement was also evaluated while the knee was extended by pulling through the quadriceps tendon. The tibial placement site affects the change in attachment site distance with passive range of motion and impingement on the intercondylar notch. Grafts passed through drill holes anterior and lateral to the insertion of the anterior fibers of the anterior cruciate ligament consistently produced impingement on the anterior outlet of the intercondylar notch. Knee extension with quadriceps tendon pull produced graft impingement in a greater arc of flexion than passive extension. Based on this study, optimum placement of the tibial hole should be at the insertion of the anterior medial fibers of the anterior cruciate ligament. Impingement recognized during surgery can be alleviated with notchplasty. With passive extension there should be a 3-mm clearance between the anterior portion of the intercondylar notch and the ligament graft to prevent the graft from impinging when the knee is actively extended.     

Elbow injuries in throwing athletes: a current concepts review

Repetitive overhead throwing imparts high valgus and extension loads to the athlete's elbow, often leading to either acute or chronic injury or progressive structural change. Tensile force is applied to the medial stabilizing structures with compression on the lateral compartment and shear stress posteriorly. Common injuries encountered in the throwing elbow include ulnar collateral ligament tears, ulnar neuritis, flexor-pronator muscle strain or tendinitis, medial epicondyle apophysitis or avulsion, valgus extension overload syndrome with olecranon osteophytes, olecranon stress fractures, osteochondritis dissecans of the capitellum, and loose bodies. Knowledge of the anatomy and function of the elbow complex, along with an understanding of throwing biomechanics, is imperative to properly diagnose and treat the throwing athlete. Recent advantages in arthroscopic surgical techniques and ligament reconstruction in the elbow have improved the prognosis for return to competition for the highly motivated athlete. However, continued overhead throwing often results in subsequent injury and symptom recurrence in the competitive athlete.     

Fatigue fracture of the ulna occurring in pitchers of fast-pitch softball

We have reported three cases of fatigue fracture of the ulna in male pitchers of fast-pitch softball. To elucidate the etiology of injury, we first selected three healthy male and three healthy female pitchers from a well-trained college team and analyzed their forearm movement by high-speed cinematography. This showed slight flexion of the elbow joints during wind-up motion, dorsal flexion of the hand joints upon releasing the ball, and extreme pronation of the forearms during the follow-through. We then took 8 mm CT scanning sections of the forearms. Using these images, we investigated shapes and areas of cross-sections of the ulna and its cortical and cancellous bones from the elbow to the hand joints. Our results reveal that the shapes of the sections are significantly different from circles at around the center of the ulna, and the cross-sectional areas are smaller in the middle one-third of the ulna than in other parts. These observations imply that fatigue fractures of the ulna in pitchers of fast-pitch softball must be torsionally induced, tending to occur at the middle one-third of the bone.     

Factors affecting the region of most isometric femoral attachments. Part I: The posterior cruciate ligament

We measured how the distance between selected tibial and femoral attachments of the PCL changes with knee flexion in six intact cadaver knee. The femoral location was the primary determinant of whether the distance increased, decreased, or remained nearly constant. The proximal-distal location of a fiber's femoral attachment had a stronger effect than had the anterior-posterior location. The tibial location had only a small statistically significant effect. These results suggest that the function of fibers within the PCL is determined primarily by their femoral attachment location. We determined all femoral attachments whose tibio-femoral distance changed 0, 2, 4, 6, 8, and 10 mm during flexion from 0 degrees to 90 degrees. No absolutely isometric point existed. Attachments whose separation distance changed less than 2 mm formed a bullet-shaped region whose base was against the roof of the intercondylar notch and whose nose pointed posteriorly and slightly distally. The axis of the "bullet" was near the proximal edge of the femoral insertion of the PCL. Along the axis, anterior attachments, located near the roof of the intercondylar notch, were more isometric than were posterior attachments, located near the cartilage. Attachments located distal to the axis moved away from the tibial insertion of the PCL when the knee was flexed. The more distal the femoral attachment, the larger the increase in tibiofemoral distance that occurred with flexion. The opposite was true of attachments proximal to the 2 mm region.     

An experimental evaluation of isometric placement for extraarticular reconstructions of the anterior cruciate ligament

We measured the changes in distance between the tibial and femoral attachment points of the extraarticular ACL substitute during knee motion. To measure the changes in distance continuously and directly, a computer-assisted experimental system was developed using an electrolyte-in-rubber transducer. We used 6 cadaveric knees to measure changes in distance of 15 combinations during a simple flexion and extension knee motion. The distance became longer with flexion in each pair of attachment locations. Although the smallest change in distance was obtained between the posterolateral site of the femoral distal metaphysis and a point posterior to the Gerdy tubercle (percent average of the maximum strain was about 12%), it was concluded that the extraarticular ACL reconstruction is not recommended from a standpoint of isometry of the substitute.     

US of the anterior bundle of the ulnar collateral ligament: findings in five cadaver elbows with MR arthrographic and anatomic comparison--initial observations

PURPOSE: To characterize the ultrasonographic (US) appearance of the anterior bundle of the ulnar collateral ligament of the elbow by comparing US images with magnetic resonance (MR) arthrograms and anatomic slices. MATERIALS AND METHODS: The ulnar collateral ligament in four cadavers (eight elbows) was blindly evaluated with US by one musculoskeletal radiologist with experience in musculoskeletal US. These results were compared with standard arthrograms, MR arthrograms, and anatomic slices by consensus reading of two musculoskeletal radiologists. The criteria for an abnormal ulnar collateral ligament included contrast material extension into the ligament or fiber discontinuity, as documented by MR arthrography and anatomic slices. RESULTS: Standard arthrography, MR arthrography, and anatomic slices demonstrated the ulnar collateral ligament to be unequivocally normal in three specimens and abnormal in two. The remaining three elbows did not meet the criteria for classification as either normal or abnormal, and thus they were excluded from the study. With US, the normal ulnar collateral ligament was fibrillar and hyperechoic between the medial epicondyle and proximal ulna. In the two abnormal cases, abnormal hypoechogenicity and ligament fiber disruption were noted. In addition, the proximal aspect of the ulnar collateral ligament varied from a cordlike structure to a broad attachment to the undersurface of the medial epicondyle with variable fat. CONCLUSION: In this small sample, the anterior bundle of the ulnar collateral ligament is identified with US by its hyperechoic and compact fibrillar echotexture. The proximal attachment of the ulnar collateral ligament has a variable appearance. Hypoechogenicity and fiber disruption indicated ulnar collateral ligament abnormality.     

Femoral insertion site of the graft used to replace the medial patellofemoral ligament influences the ligament dynamic changes during knee flexion and the clinical outcome

Purpose

This study’s purpose was to investigate how an ideal anatomic femoral attachment affects the dynamic length change pattern of a virtual medial patellofemoral ligament (MPFL) from an extended to a highly flexed knee position; to determine the relative length and length change pattern of a surgically reconstructed MPFL; and to correlate femoral attachment positioning, length change pattern, and relative graft length with the clinical outcome.

Methods

Twenty-four knees with isolated nonanatomic MPFL reconstruction were analysed by three-dimensional computed tomography at 0°, 30°, 60°, 90°, and 120° of knee flexion. The lengths of the MPFL graft and a virtual anatomic MPFL were measured. The pattern of length change was considered isometric if the length distance changed <5 mm through the entire dynamic range of motion.

Results

Knee flexion significantly affected the path lengths between the femoral and patellar attachments. The length of the anatomic virtual MPFL decreased significantly from 60° to 120°. Its maximal length was 56.4 ± 6.8 mm at 30°. It was isometric between 0° and 60°. The length of the nonanatomic MPFL with a satisfactory clinical result decreased during flexion from 0° to 120°. Its maximal length was 51.6 ± 4.6 mm at 0° of knee flexion. The lengths measured at 0° and 30° were isometric and statistically greater than the lengths measured at higher flexion degrees. The failed nonanatomic MPFL reconstructions were isometric throughout the dynamic range, being significantly shorter (27.1 ± 13.3 %) than anatomic ligaments.

Conclusion

The femoral attachment point significantly influences the relative length and the dynamic length change of the grafts during knee flexion–extension and graft isometry. Moreover, it influences the long-term outcome of the MPFL reconstructive surgery. A nonanatomic femoral fixation point should not be considered the cause of persistent pain and instability after MPFL reconstruction in all cases.

Level of evidence

III.

     

Medial patellofemoral ligament anatomy: implications for its surgical reconstruction

The purpose of the present study, based on 23 cadaveric knees, was to perform a detailed anatomical analysis of the medial patellofemoral ligament (MPFL), especially its femoral attachment, its relationships with the vastus medialis obliquus (VMO) and the medial collateral ligament, with the objective of improving its surgical reconstruction. The femoral insertion of the MPFL was defined using an orthonormal frame centered on the middle of the femoral MPFL insertion. The whole measurements were taken using a millimetric compass with a precision of ±1 mm. The MPFL was always observed, its length was 57.7 ± 5.8 mm, the junction between the VMO and the MPFL always present measured 25.7 ± 6.0 mm. When it comes to MPFL reconstruction, the key point is its positioning in the femoral insertion because it is this insertion that is going to restore isometry. By using the orthonormal frame it has to be positioned 10 mm behind the medial epicondyle and 10 mm distal to the adductor tubercle.     

Positioning of the posterior cruciate ligament

The isometric position in ligament reconstruction is the one in which there is little or no change in the length of the graft with range of motion of the joint. It varies according to the positions of the tunnels that will become the attachment sites of whatever graft is being used. Better understanding of this concept that greatly improved the surgical results of intra-articular reconstructions of the anterior cruciate ligament. Unfortunately, the results of posterior cruciate ligament (PCL) reconstructions have lagged behind. A better understanding of the isometry of the PCL and how it relates to the positioning of a graft at the time of reconstruction should help improve the situation. The current scientific studies on the PCL as they relate to isometry are evaluated and summarised in this paper. The tibial isometric point was universally less sensitive to changes in position than was the femoral isometric point. However, all the points that were evaluated for the tibia fell within the normal insertion area of the PCL. This has important ramifications when extrapolating these laboratory studies to the operating room, where it is imperative to get the tibial tunnel or attachment site distal enough on the tibia so that it will be in the usual anatomic location of the PCL. There is less uniformity when it comes to the femoral isometric point, but once again the isometric point from each of the studies fell within the normal anatomic femoral attachment site. The differences between the selected points may be explained by the different study designs.