肘关节内侧副韧带前束重建的生物力学研究

目的通过测量肘关节内侧副韧带(medial collateral ligament,MCL)前束生物力学指标,探讨前束完整及重建后对肘关节外翻稳定性的影响,评价采用人工肌腱、界面螺钉重建MCL前束疗效。方法成人完整上肢标本12具,男8具,女4具;左、右侧各6具;制成肘关节"骨-韧带"标本。采用生物力学及压敏胶片测量方法,分别测量MCL前束完整(对照组)及使用人工肌腱、界面螺钉重建后(实验组)肘关节屈曲0、30、60、90°时关节外翻松弛度、肱尺关节受力面积及肘关节内压强。结果两组在肘关节不同屈曲角度下,组内及组间关节松弛度比较,差异均无统计学意义(P>0.05)。除肘关节屈曲0°时两组肘关节压强小于其余屈曲角度(P<0.05),及对照组小于实验组(P<0.05)外,两组其余各角度组内及组间比较差异均无统计学意义(P>0.05)。除对照组内肘关节屈曲0°时肱尺关节受力面积大于其余屈曲角度(P<0.05)外,两组其余各角度组内及组间比较差异均无统计学意义(P>0.05)。结论 MCL前束对维持肘关节外翻稳定性具有重要意义,金属界面螺钉加人工肌腱重建后可即刻恢复内侧稳定。     

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.     

Stability after medial collateral ligament release in total knee arthroplasty.

Six knees from cadavers were tested for change in stability after release of the medial collateral ligament with posterior cruciate-retaining and substituting total knee replacements. Load deformation curves of the joint were recorded in full extension and 30 degrees, 60 degrees, and 90 degrees flexion under a 10 N-m varus and valgus torque, 1.5 N-m internal and external rotational torque, and a 35 N anterior and posterior force to test stability in each knee. The intact specimen and posterior cruciate ligament-retaining total joint replacement were tested for baseline comparisons. The superficial medial collateral ligament was released, followed by release of the posterior cruciate ligament. The knee then was converted to a posterior-stabilized implant. After medial collateral ligament release, valgus laxity was statistically significantly greater at 30 degrees, 60 degrees, and 90 degrees flexion after posterior cruciate ligament sacrifice than it was when the posterior cruciate ligament was retained. The posterior-stabilizing post added little to varus and valgus stability. Small, but significant, differences were seen in internal and external rotation before and after posterior cruciate ligament sacrifice. The posterior-stabilized total knee arthroplasty was even more rotationally constrained in full extension than the knee with intact medial collateral ligament and posterior cruciate ligament.     

Single-strand ligament reconstruction of the medial collateral ligament restores valgus elbow stability

The purpose of this study was to determine the contribution of the central portion of the anterior bundle of the medial collateral ligament (MCL) to elbow stability and to evaluate the effectiveness of a single-strand MCL reconstruction in restoring elbow stability. Testing of 11 fresh-frozen upper extremities was first performed on the intact elbow and then with the capsule, flexor-pronator muscle group, posterior bundle, anterior or posterior band, and central band cut sequentially. Next, a single-strand reconstruction of the MCL was performed. The elbow was moved passively through a full arc of flexion in both varus and valgus gravity-loaded positions. Ulnar movement with respect to the humerus was analyzed by means of an electromagnetic tracking system. Maximum varus-valgus laxity throughout the arc of supinated flexion and pronated flexion was 6.6 degree plus minus 2.4 degree and 7.4 degree plus minus 2.0 degree, respectively, for the intact specimen, 34.2 degree plus minus 5.6 degree and 37.7 degree plus minus 11.8 degree for the specimen with all of the medial valgus elbow stabilizers cut, and 9.0 degree plus minus 2.5 degree and 10.5 degree plus minus 2.7 degree for the reconstructed specimen. Maximum varus-valgus laxity was not significantly different among any of the sectioning sequences until the central band was cut (P <.0001). There was no significant difference in maximum varus-valgus laxity between the intact and reconstructed elbows (P <.05). Our results demonstrate that the central band is an important valgus stabilizer of the elbow and that a simplified single-strand reconstruction is able to restore stability to the MCL-deficient elbow.     

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。     

Interaction between the ACL graft and MCL in a combined ACL+MCL knee injury using a goat model

The optimal treatment for the MCL in the combined ACL and MCL-injured knee is still controversial. Therefore, we designed this study to examine the mechanical interaction between the ACL graft and the MCL in a goat model using a robotic/universal force-moment sensor testing system. The kinematics of intact, ACL-deficient, ACL-reconstructed, and ACL-reconstructed/ MCL-deficient knees, as well as the in situ forces in the ACL, ACL graft, and MCL were determined in response to two external loading conditions: 1) anterior tibial load of 67 N and 2) valgus moment of 5 N-m. With an anterior tibial load, anterior tibial translation in the ACL-deficient knee significantly increased from 2.0 and 2.2 mm to 15.7 and 18.1 mm at 30 degrees and 60 degrees of knee flexion, respectively. The in situ forces in the MCL also increased from 8 to 27 N at 60 degrees of knee flexion. ACL reconstruction reduced the anterior tibial translation to within 2 mm of the intact knee and significantly reduced the in situ force in the MCL to 17 N. However, in response to a valgus moment, the in situ forces in the ACL graft increased significantly by 34 N after transecting the MCL. These findings show that ACL deficiency can increase the in situ forces in the MCL while ACL reconstruction can reduce the in situ forces in the MCL in response to an anterior tibial load. On the other hand, the ACL graft is subjected to significantly higher in situ forces with MCL deficiency during an applied valgus moment. Therefore, the ACL-reconstructed knee with a combined ACL and MCL injury should be protected from high valgus moments during early healing to avoid excessive loading on the graft.     

Experimental elbow instability after transection of the medial collateral ligament

In 12 osteoligamentous autopsy elbow preparations, the stability of the elbow was independent of the collateral ligament with flexion of less than 20 degrees and greater than 120 degrees. The anterior part of the collateral medial ligament was the prime stabilizer of the elbow in this range of motion, i.e., the flexion range of function. The maximum valgus and internal rotatory instability after transection of the medial collateral ligament, 20.2 degrees and 21.0 degrees, respectively, were found at elbow flexions from 60 degrees to 70 degrees. Selective repair or reconstruction of the anterior part of the elbow medial collateral ligament may prove to be effective in the treatment of acute or chronic elbow instability.     

Einfluss der Transplantatausrichtung des vorderen Bündels des medialen ulnaren Kollateralbandes auf die Valgusstabilität des Ellenbogens

Background

The aim of the present study was to examine whether the primary stability of the medial ulnar collateral elbow ligament (UCL) of a double-bundle technique with anatomic drill hole position is superior to a non-anatomical position or a single-bundle technique.

Materials and methods

Ten fresh-frozen upper extremities (mean age 76 years (range 58–89)) were mounted in the testing apparatus. First, the valgus-stability with intact medial UCL was tested in 120, 90, 60, 30 and 0?° of flexion with a continuously increasing load to 7.5 Nm. Afterwards the pronator was split and the anterior bundle of the medial UCL cut, followed by a new sequential testing. Ulnar drill holes were installed hereafter, both in an anatomical and non-anatomical position. Tendon grafts were placed to simulate two double bundle (double bundle 1?= drill hole anatomical position; double bundle 2?= drill hole extra-anatomical) and one single bundle reconstruction. Sequential testing was done of each reconstruction. Statistical analysis was performed by means of a variance analysis per Scheffe’s post hoc technique.

Results

In a valgus stress of 7.5 Nm, mean valgus deformation in an intact MUCL at 90° elbow flexion was 7.4?±?2.4?° and at full extension 7.4?±?2.6?°. A significant increase in valgus instability was observed (p?Conclusion In this biomechanical study, the single-bundle reconstruction proved equal to the double-bundle technique. Both techniques showed a sufficient stabilization against valgus stress.     

Distribution of in situ forces in the anterior cruciate ligament in response to rotatory loads.

The anterior cruciate ligament (ACL) can be anatomically divided into anteromedial (AM) and posterolateral (PL) bundles. Current ACL reconstruction techniques focus primarily on reproducing the AM bundle, but are insufficient in response to rotatory loads. The objective of this study was to determine the distribution of in situ force between the two bundles when the knee is subjected to anterior tibial and rotatory loads. Ten cadaveric knees (50+/-10 years) were tested using a robotic/universal force-moment sensor (UFS) testing system. Two external loading conditions were applied: a 134 N anterior tibial load at full knee extension and 15 degrees, 30 degrees, 60 degrees, and 90 degrees of flexion and a combined rotatory load of 10 Nm valgus and 5 Nm internal tibial torque at 15 degrees and 30 degrees of flexion. The resulting 6 degrees of freedom kinematics of the knee and the in situ forces in the ACL and its two bundles were determined. Under an anterior tibial load, the in situ force in the PL bundle was the highest at full extension (67+/-30 N) and decreased with increasing flexion. The in situ force in the AM bundle was lower than in the PL bundle at full extension, but increased with increasing flexion, reaching a maximum (90+/-17 N) at 60 degrees of flexion and then decreasing at 90 degrees. Under a combined rotatory load, the in situ force of the PL bundle was higher at 15 degrees (21+/-11 N) and lower at 30 degrees of flexion (14+/-6 N). The in situ force in the AM bundle was similar at 15 degrees and 30 degrees of knee flexion (30+/-15 vs. 35+/-16 N, respectively). Comparing these two external loading conditions demonstrated the importance of the PL bundle, especially when the knee is near full extension. These findings provide a better understanding of the function of the two bundles of the ACL and could serve as a basis for future considerations of surgical reconstruction in the replacement of the ACL.     

Medial collateral ligament insertion site and contact forces in the ACL-deficient knee.

The objectives of this research were to determine the effects of anterior cruciate ligament (ACL) deficiency on medial collateral ligament (MCL) insertion site and contact forces during anterior tibial loading and valgus loading using a combined experimental-finite element (FE) approach. Our hypothesis was that ACL deficiency would increase MCL insertion site forces at the attachments to the tibia and femur and increase contact forces between the MCL and these bones. Six male knees were subjected to varus-valgus and anterior-posterior loading at flexion angles of 0 degrees and 30 degrees. Three-dimensional joint kinematics and MCL strains were recorded during kinematic testing. Following testing, the MCL of each knee was removed to establish a stress-free reference configuration. An FE model of the femur-MCL-tibia complex was constructed for each knee to simulate valgus rotation and anterior translation at 0 degrees and 30 degrees, using subject-specific bone and ligament geometry and joint kinematics. A transversely isotropic hyperelastic material model with average material coefficients taken from a previous study was used to represent the MCL. Subject-specific MCL in situ strain distributions were used in each model. Insertion site and contact forces were determined from the FE analyses. FE predictions were validated by comparing MCL fiber strains to experimental measurements. The subject-specific FE predictions of MCL fiber stretch correlated well with the experimentally measured values (R2 = 0.95). ACL deficiency caused a significant increase in MCL insertion site and contact forces in response to anterior tibial loading. In contrast, ACL deficiency did not significantly increase MCL insertion site and contact forces in response to valgus loading, demonstrating that the ACL is not a restraint to valgus rotation in knees that have an intact MCL. When evaluating valgus laxity in the ACL-deficient knee, increased valgus laxity indicates a compromised MCL.     

Valgus medial collateral ligament rupture causes concomitant loading and damage of the anterior cruciate ligament

This study tested the hypothesis that application of a valgus force necessary to create a complete medial collateral ligament (MCL) injury causes damage to the anterior cruciate ligament (ACL). Twelve cadaveric knees were used to measure concomitant loading and damage to the ACL in valgus knee loading sufficient to cause a grade III MCL injury. Displacement sensors were placed on the anteromedial bundle of the ACL and posterior oblique ligament to monitor tensile strain during creation of the MCL injury. A valgus moment was applied to knees flexed at 30 degrees, displacing the joint into valgus rotation beyond MCL rupture. Following valgus loading and MCL injury, femur-ACL-tibia specimens were tested to failure to compare ACL mechanical integrity to noninjured control specimens. Average ACL strength in MCL ruptured knees (1250 +/- 90 N) was statistically lower (P < or = .05) than that for control knees (2110 +/- 50 N). Strain measurements exhibited concomitant posterior oblique ligament strain during valgus loading, whereas ACL strain increased substantially only after MCL rupture. These data indicate that the ACL can be compromised in isolated grade III MCL injuries.     

Elbow ligament strain under valgus load: a biomechanical study.

This study assessed the importance of the anterior and posterior bundles of the medial collateral ligament in the elbow by measuring in situ strain in response to valgus loads at three positions of forearm rotation throughout a full arc of motion. Strain in the anterior bundle was significantly greater than in the posterior bundle and increased with more flexion. The anterior bundle developed strain at a lower flexion angle (30 degrees) than the posterior bundle (60 degrees). Strain ratio increased with load increase for all flexion angles. Forearm position minimally affected strain. These results indicate that the anterior bundle is important in resisting a valgus load, particularly in mid-flexion, while the importance of the posterior bundle increases as the elbow approaches full flexion.     

Instability of knees with ligament lesions. Cadaver studies of the anterior cruciate ligament

We studied the importance of the two parts of the anterior cruciate ligament (ACL), the medial collateral ligament (MCL), and the posterior medial capsule (PMC) to translatory and spontaneous axial rotatory instability in 15 osteoligamentous knee preparations. Instability was recorded continuously from zero to 90 degrees of flexion with application of a constant force to the tibia. Isolated cutting of the ACL caused a moderate anterior translatory movement, which increased if the MCL was also cut. Transection also of the PMC resulted in an even larger range of anterior translatory movement. Combined lesions to the MCL and the PMC and the posterolateral part of the ACL did not cause such instability provided the anteromedial part of the ACL was intact. Application of a valgus moment to specimens with injured ACL and medial structures induced a spontaneous anteromedial subluxation of the tibia in a semiflexed position. When flexion was increased to 70-80 degrees, a sudden reduction was observed.     

Instability of knees with ligament lesions: Cadaver studies of the anterior cruciate ligament

We studied the importance of the two parts of the anterior cruciate ligament (ACL), the medial collateral ligament (MCL), and the posterior medial capsule (PMC) to translatory and spontaneous axial rotatory instability in 15 osteoligamentous knee preparations. Instability was recorded continuously from zero to 90 degrees of flexion with application of a constant force to the tibia. Isolated cutting of the ACL caused a moderate anterior translatory movement, which increased if the MCL was also cut. Transection also of the PMC resulted in an even larger range of anterior translatory movement. Combined lesions to the MCL and the PMC and the posterolateral part of the ACL did not cause such instability provided the anteromedial part of the ACL was intact.

Application of a valgus moment to specimens with injured ACL and medial structures induced a spontaneous anteromedial subluxation of the tibia in a semiflexed position. When flexion was increased to 70–80 degrees, a sudden reduction was observed     

Instability of knees with ligament lesions: Cadaver studies of the anterior cruciate ligament

We studied the importance of the two parts of the anterior cruciate ligament (ACL), the medial collateral ligament (MCL), and the posterior medial capsule (PMC) to translatory and spontaneous axial rotatory instability in 15 osteoligamentous knee preparations. Instability was recorded continuously from zero to 90 degrees of flexion with application of a constant force to the tibia. Isolated cutting of the ACL caused a moderate anterior translatory movement, which increased if the MCL was also cut. Transection also of the PMC resulted in an even larger range of anterior translatory movement. Combined lesions to the MCL and the PMC and the posterolateral part of the ACL did not cause such instability provided the anteromedial part of the ACL was intact.

Application of a valgus moment to specimens with injured ACL and medial structures induced a spontaneous anteromedial subluxation of the tibia in a semiflexed position. When flexion was increased to 70-80 degrees, a sudden reduction was observed     

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。     

Anatomical versus Non-Anatomical Single Bundle Anterior Cruciate Ligament Reconstruction: A Cadaveric Study of Comparison of Knee Stability

Background

The purpose of this study was to compare the initial stability of anatomical and non-anatomical single bundle anterior cruciate ligament (ACL) reconstruction and to determine which would better restore intact knee kinematics. Our hypothesis was that the initial stability of anatomical single bundle ACL reconstruction would be superior to that of non-anatomical single bundle ACL reconstruction.

Methods

Anterior tibial translation (ATT) and internal rotation of the tibia were measured with a computer navigation system in seven pairs of fresh-frozen cadaveric knees under two testing conditions (manual maximum anterior force, and a manual maximum anterior force combined with an internal rotational force). Tests were performed at 0, 30, 60, and 90 degrees of flexion with the ACL intact, the ACL transected, and after reconstruction of one side of a pair with either anatomical or non-anatomical single bundle ACL reconstruction.

Results

Under manual maximal anterior force, both reconstruction techniques showed no significant difference of ATT when compared to ACL intact knee state at 30° of knee flexion (p > 0.05). Under the combined anterior and internal rotatory force, non-anatomical single-bundle ACL reconstruction showed significant difference of ATT compared to those in ACL intact group (p < 0.05). In contrast, central anatomical single bundle ACL reconstruction showed no significant difference of ATT compared to those in ACL intact group (p > 0.05). Internal rotation of the tibia showed no significant difference in the ACL intact, the ACL transected, non-anatomical reconstructed and anatomical reconstructed knees.

Conclusions

Anatomical single bundle ACL reconstruction restored the initial stability closer to the native ACL under combined anterior and internal rotational forces when compared to non-anatomical ACL single bundle reconstruction.     

Biomechanics of a double prosthetic ligament in the anterior cruciate deficient knee

We have assessed the biomechanical properties of a 'double-bundle' prosthetic ligament replacing the anterior cruciate in cadaver knees. We compared the results with those of single bundle 'over-the-top' and 'through-the-condyle' techniques, performing anterior drawer tests at 20 degrees and 90 degrees knee flexion. The over-the-top reconstruction gave better anteroposterior stability at 20 degrees, while the through-the-condyle repair was more stable at 90 degrees. The double-bundle reconstruction gave practically normal anterior stability at both 20 degrees and 90 degrees.     

Anterolateral rotatory instability of the knee. Cadaver study of extraarticular patellar-tendon transposition

A cadaver knee-testing system was used to analyze the effect of an extraarticular reconstruction for anterolateral rotatory instability in which the lateral one third of the patellar tendon with a patellar bone block was transposed to the lateral femoral condyle. Ligament and reconstruction tendon forces were measured using buckle transducers, and joint motion was measured using an instrumented spatial linkage as 90 N anteriorly directed tibial loads were applied to seven knee specimens at 0 degree, 30 degrees, 60 degrees, and 90 degrees of flexion by a pneumatic load apparatus. This was done for each knee with first an intact, then an excised anterior cruciate ligament, and finally the extraarticular reconstruction. Forces in the transposed graft exhibited an isotonic pattern over the flexion range, unlike the intact anterior cruciate ligament, which was more highly loaded in extension than in flexion. The transposition of the patellar tendon led to external rotation of the tibia in both unloaded and anterior load conditions throughout flexion. Collateral ligament forces increased with anterior cruciate ligament excision, with the force in the medial ligament remaining higher than normal with the reconstruction, while the lateral forces became lower than normal.     

Interaction between the ACL graft and MCL in a combined ACL+MCL knee injury using a goat model

The optimal treatment for the MCL in the combined ACL and MCL-injured knee is still controversial. Therefore, we designed this study to examine the mechanical interaction between the ACL graft and the MCL in a goat model using a robotic/universal force-moment sensor testing system. The kinematics of intact, ACL-deficient, ACL-reconstructed, and ACL-reconstructed/MCL-deficient knees, as well as the in situ forces in the ACL, ACL graft, and MCL were determined in response to two external loading conditions: 1) anterior tibial load of 67 N and 2) valgus moment of 5 N-m. With an anterior tibial load, anterior tibial translation in the ACL-deficient knee significantly increased from 2.0 and 2.2 mm to 15.7 and 18.1 mm at 30° and 60° of knee flexion, respectively. The in situ forces in the MCL also increased from 8 to 27 N at 60° of knee flexion. ACL reconstruction reduced the anterior tibial translation to within 2 mm of the intact knee and significantly reduced the in situ force in the MCL to 17 N. However, in response to a valgus moment, the in situ forces in the ACL graft increased significantly by 34 N after transecting the MCL. These findings show that ACL deficiency can increase the in situ forces in the MCL while ACL reconstruction can reduce the in situ forces in the MCL in response to an anterior tibial load. On the other hand, the ACL graft is subjected to significantly higher in situ forces with MCL deficiency during an applied valgus moment. Therefore, the ACL-reconstructed knee with a combined ACL and MCL injury should be protected from high valgus moments during early healing to avoid excessive loading on the graft.