Reproducibility of anatomic tibial landmarks for anterior cruciate ligament reconstructions.

We evaluated the reproducibility of landmarks used for accurate anatomic placement of the tibial tunnel in anterior cruciate ligament reconstruction. Landmarks evaluated were the medial tibial eminence, the posterior cruciate ligament, the "over-the-back" position, the true posterior border of the tibia, and the posterior border of the lateral meniscus. Forty-two pairs of cadaveric knees were dissected, and anatomic measurements were made regarding the anterior cruciate ligament insertion and these various landmarks. Statistical analysis was used to confirm reproducibility and significance. Measurements based on the medial tibial eminence and posterior border of the meniscus were particularly erratic. The most reproducible anatomic landmark was the posterior cruciate ligament. The anterior border of the posterior cruciate ligament was consistently 6.7 mm posterior to the posterior border of the anterior cruciate ligament and 10.9 mm posterior to the central sagittal insertion point of the anterior cruciate ligament. The over-the-back position was consistently in contact with the anterior border of the posterior cruciate ligament if the knee was flexed with a posterior-directed force applied. In this position, the over-the-back position was equally reproducible as compared with the posterior cruciate ligament. Measurements gauged from the true posterior border of the tibia gave a second rigid bony landmark but with a wider standard deviation than the posterior cruciate ligament-based landmarks. The relative anterior-posterior dimension of the tibia did not correlate with the relationship between the anterior cruciate ligament and other anatomic landmarks.     

单束重建前交叉韧带骨道位置对临床效果影响的研究

目的:探讨前交叉韧带重建术骨道位置对临床效果的影响。方法:2005年5月至12月于我所行自体腘绳肌腱单束重建前交叉韧带手术患者72例,采用其侧位X线平片测量骨道位置,结合膝关节功能评分、KT-2000测试结果进行分析。结果:患者的IKDC、Lysholm和Tegner评分以及KT-2000在134N下屈膝30度和90度位膝关节前后位移情况均较术前显著改善(P<0.01)。股骨骨道位于Blumensaat’s线的后23.87%,胫骨骨道位于胫骨平台全长的前38.25%。膝关节伸直受限患者胫骨骨道位于胫骨平台前34.19%,伸直正常患者胫骨骨道位于胫骨平台的前38.91%,二者相比具有显著性差异(P<0.05〉。KT-2000屈膝30度位膝关节前后位移值大于等于3mm患者的胫骨骨道位于胫骨平台的前44.78%,位移小于3mm患者胫骨骨道位于胫骨平台的37.39%,二者相比具有显著性差异(P<0.01)。结论:单束重建前交叉韧带手术使患者关节稳定性与功能均得到显著改善。X线测量可较客观、准确地反映骨道定位情况,骨道位置与临床效果相关;本次研究显示比较理想的骨道位置在X线侧位片上位于胫骨平台的前34~37%。     

核磁图像上后交叉韧带止点位置的测量及临床应用

目的:在核磁共振图像(MRI)上观察和测量后交叉韧带(PCL)止点位置,为PCL重建骨道定位和术后骨道评估提供帮助。方法:选择102例PCL完整的患者,在MRI的SE T1WI序列矢状位图像上,分别测量PCL股骨和胫骨的止点位置和大小,以及胫骨止点中点到胫骨平台的垂直距离。利用术前MRI测量结果指导12例PCL断裂患者重建术中的骨道定位,术后利用CT评估骨道位置。结果:PCL股骨止点位于Blumensaat线的前下二分之一,止点长度为(11.08±1.51)mm,占Blumensaat线的37.55%;胫骨止点位于胫骨斜坡的后下二分之一,止点长度为(12.37±1.98)mm,占斜坡长度的44.48%。从胫骨止点中心点到胫骨平台最高点的垂直距离为(15.21±2.203)mm。利用术前测量结果指导术中骨道定位和术后骨道位置评估,骨道位置正确。结论:术前MRI测量结果,可以指导术中骨道定位,帮助术后骨道位置的评估。     

Lateral radiographic study of the tibial sagital insertions of the anteromedial and posterolateral bundles of human anterior cruciate ligament

Recently, the femoral attachments of anteromedial and posterolateral bundles of anterior cruciate ligament (ACL) have been extensively discussed, however, few publications have mentioned radiographic measurements of the tibial insertions of two bundles. The aim of this study is to determine the radiographic measurements of the tibial sagital insertions for anteromedial (AM) and posterolateral (PL) bundles of ACL. Thirty-one cadaveric proximal tibias were used. After identification of the AM and PL bundles insertion sites on the tibia, the insertion center and the other anatomic landmarks were marked with a lead pin, and lateral radiographs were taken. Sagital percentage is a percentage of the location of the insertion point calculated from the anterior margin of the tibia in the anteroposterior direction. Anterior edge of ACL averaged 25.0%, center of AM averaged 34.6%, center of PL averaged 38.4%, posterior edge of ACL averaged 50.2%. This study defines the radiographic location of the tibial insertions of the anteromedial and posterolateral bundles of ACL. This contributes to more precise evaluation of anatomical double bundle ACL reconstruction surgery postoperatively.     

Histological analysis of the tibial anterior cruciate ligament insertion

Purpose

This study was performed to investigate the morphology of the tibial anterior cruciate ligament (ACL) by histological assessment.

Methods

The native (undissected) tibial ACL insertion of six fresh-frozen cadaveric knees was cut into four sagittal sections parallel to the long axis of the medial tibial spine. For histological evaluation, the slices were stained with haematoxylin and eosin, Safranin O and Russell–Movat pentachrome. All slices were digitalized and analysed at a magnification of 20×.

Results

The anterior tibial ACL insertion was bordered by a bony anterior ridge. The most medial ACL fibres inserted from the medial tibial spine and were adjacent to the articular cartilage of the medial tibial plateau. Parts of the bony insertions of the anterior and posterior horns of the lateral meniscus were in close contact with the lateral part of the tibial ACL insertion. A small fat pad was located just posterior to the functional ACL fibres. The anterior–posterior length of the medial ACL insertion was an average of 10.8 ± 1.1 mm compared with the lateral, which was only 6.2 ± 1.1 mm (p < 0.001). There were no central or posterolateral inserting ACL fibres.

Conclusions

The shape of the bony tibial ACL insertion was ‘duck-foot-like’. In contrast to previous findings, the functional mid-substance fibres arose from the most posterior part of the ‘duck-foot’ in a flat and ‘c-shaped’ way. The most anterior part of the tibial ACL insertion was bordered by a bony anterior ridge and the most medial by the medial tibial spine. No posterolateral fibres nor ACL bundles have been found histologically. This histological investigation may improve our understanding of the tibial ACL insertion and may provide important information for anatomical ACL reconstruction.

     

The fixation strength of tibial PCL press-fit reconstructions

Purpose  

A secure tibial press-fit technique in posterior cruciate ligament reconstructions is an interesting technique because no hardware is necessary. For anterior cruciate ligament (ACL) reconstruction, a few press-fit procedures have been published. Up to the present point, no biomechanical data exist for a tibial press-fit posterior cruciate ligament (PCL) reconstruction. The purpose of this study was to characterize a press-fit procedure for PCL reconstruction that is biomechanically equivalent to an interference screw fixation.     

前交叉韧带解剖重建理念与方法

前交叉韧带(Anterior Cruciate Ligament,ACL)解剖重建技术是基于ACL解剖理论发展起来的一项手术技术。ACL解剖重建是根据ACL的解剖特点进行功能重建,恢复ACL原有的尺寸、韧带胶原走行方向和止点位置。解剖重建不仅包括双束和单束重建,而且包括以此理论为基础的ACL重建术后的翻修与加固。本文对ACL的解剖重建技术进行介绍,针对在关节镜下如何观察原ACL的止点位置,测量止点长宽,选择骨道位置,如何利用影像学进行评价进行了详细的阐述和解释,并介绍了该技术目前的临床评价结果。同时,本文对ACL解剖重建和传统"经典"重建方法的区别进行了重点说明与解释,为提高国内医师对ACL解剖重建技术的认识提供参考和帮助。     

Tibiofemoral relationship following anatomic triple-bundle anterior cruciate ligament reconstruction

Purpose

The purpose of this study was to investigate the tibiofemoral relationship sequentially before and after anatomic triple-bundle (TB) anterior cruciate ligament (ACL) reconstruction in the same patients.

Methods

Nine patients with complete unilateral ACL rupture participated in this study. Anatomic TB ACL reconstruction was performed using autogenous semitendinosus tendon grafts. Computed tomography images were obtained before surgery as well as 3 weeks and 6 months afterwards. During image acquisition, the patient’s knees were fully extended in the supine position. Using three-dimensional computer models, anterior–posterior and medial–lateral displacement of the tibia relative to the femur were evaluated for each period, as were internal–external and varus–valgus rotation, followed by calculation of side-to-side differences in parameters. As the control group, 7 healthy volunteers were evaluated.

Results

The tibia was located anteriorly by 1.4 ± 0.9 mm and rotated internally by 2.1 ± 1.7° before surgery, while the tibia was located posteriorly by 2.0 ± 1.2 mm and rotated externally by 3.4 ± 3.5° 3 weeks after surgery. Six months after surgery, there was no significant difference between the patient and control groups.

Conclusions

The anteriorly located and internally rotated tibia in ACL-deficient knees was over-constrained (posterior displacement and external rotation) 3 weeks after anatomic TB ACL reconstruction, but returned to the normal position 6 months afterwards. Therefore, anatomic tunnel placement, appropriate initial tension, and moderate rehabilitation can be the key for return to the normal tibiofemoral relationship after ACL reconstruction.

Level of evidence

Therapeutic study, Level IV.     

Tibial attachment area of the anterior cruciate ligament in the extended knee position

Knowledge of the anatomy of the anterior cruciate ligament (ACL), including its course and orientation in relation to the roof of the intercondylar fossa, is a prerequisite for successful intra-articular ACL reconstruction. To attain precision placement of the tibial attachment site and to avoid graft/roof conflict in the extended knee position, we assessed the anteroposterior tibial insertion of the ACL in the midsagittal plane of the extended knee. We measured the anterior-posterior (AP) limits and the center of the tibial attachment area of the ACL from the anterior tibial margin. The inclination angle of the intercondylar fossa roof was measured with respect to the shaft axis of the femur. The tibial attachment area of the ACL was determined in ten cadaveric knees. Using the cryoplaning technique, we determined the tibital attachment of the ACL in five knees. Using contrast magnetic resonance arthrography (MRA), we measured the tibial insertion of the ACL in 35 patients (23 male and 12 female) with intact ACLs. The total AP midsagittal diameter of the tibia averaged 51.0±5.8 mm in the cadaveric knees, 49 mm on cryosections, and 53.7 mm in men and 49.0 mm in women with MRA. The average anterior limit of the ACL, measured from the anterior tibial margin, was 14±4.2 mm in the cadaveric knees, 12.1 mm at cryosectional anatomy, and 15.2 mm in men and 13.4 mm in women with MRA. The center of the tibial attachment area was located at 21±2.6 mm in cadaveric knees, at 21.2 mm on cryosections, and at 23.7 mm in men and at 21.4 mm in women with MRA. The posterior limit of the tibial attachment area of the ACL was 29.0±4.1 mm in cadaveric knees, 30.6 mm on cryosections, 32.1 mm in male and 29.4 mm female patients with MRA. The roof inclination angle measured on average 39.8° on cryosections and 36.8° in men and 35.2° in women on MRA. Based on these morphometric data and to avoid notch/graft conflict in knee extension, we advocate placing the center of the tibial tunnel at 44% of the tibia diameter posterior and parallel to the individual intercondylar roof inclination angle.     

Roles of ACL remnants in knee stability

Purpose

This study evaluated knee laxity in anterior tibial translation and rotation following removal of anterior cruciate ligament (ACL) remnants using a computer navigation system.

Methods

This prospective study included 50 knees undergoing primary ACL reconstruction using a navigation system. ACL remnants were classified into four morphologic types: Type 1, bridging between the roof of the intercondylar notch and tibia; Type 2, bridging between the posterior cruciate ligament and tibia; Type 3, bridging between the anatomical insertions of the ACL on the lateral wall of the femoral condyle and the tibia; and Type 4, no bridging of ACL remnants. Anterior tibial translation and rotatory laxity were measured before and after remnant resection using a navigation system at 30°, 60°, and 90° of knee flexion. The amount of change in anterior tibial translation and rotatory laxity of each type was compared among the types.

Results

The different morphologic types of ACL remnants were as follows: Type 1, 15 knees; Type 2, 9 knees; Type 3, 6 knees; and Type 4, 20 knees. The amount of change in anterior tibial translation and rotatory laxity at 30° knee flexion in Type 3 was significantly larger than in the other types. There were no significant differences in either tibial translation or rotatory laxity at 60° and 90° knee flexion among the types.

Conclusions

In Type 3, ACL remnants contributed to anteroposterior and rotatory knee laxity evaluated at 30° knee flexion. The bridging point of the remnants is important to knee laxity. The Type 3 remnant should be preserved as much as possible when ACL reconstruction surgery is performed.

Level of evidence

Prognostic study, Level II.     

Postoperative evaluation of tibial footprint and tunnels characteristics after anatomic double-bundle anterior cruciate ligament reconstruction with anatomic aimers

Following anatomic double-bundle anterior cruciate ligament (ACL) reconstruction with hamstring tendon autografts, 38 consecutive patients were evaluated with high-speed three-dimensional computed tomography. Scans were performed within 3 days following surgery. The length and width of the reconstructed ACL footprint were measured on axial images. Then, 3D images were converted into 2D with radiologic density for measurement purposes. Tunnel orientation was measured on AP and lateral views. In the sagittal plane, the center of the anteromedial (AMB) and posterolateral bundle (PLB) tibial attachment positions was calculated as the ratio between the geometric insertion sites with respect to the sagittal diameter of the tibia. In addition, the length from the anterior tibial plateau to the retro-eminence ridge was measured; the relationship of this line with the centers of the AM and PL tunnels was then measured. The AP length of the reconstructed footprint was 17.1 mm ± 1.9 mm and the width 7.3 mm ± 1.2 m. The distance from retro-eminence ridge to center of AM tunnel was 18.8 mm ± 2.8 mm, and the distance from RER to center of PL tunnel was 8.7 mm ± 2.6 mm. The distance between tunnels center was 10.1 mm ± 1.7 mm. There were no significant differences between the intra- and inter-observer measurements. The bone bridge thickness was 2.1 mm ± 0.8 mm. In the sagittal plane, the centers of the tunnel apertures were located at 35.7% ± 6.7% and 53.7% ± 6.8% of the tibia diameter for the AMB and PLB, respectively. The surface areas of the tunnel apertures were 46.3 mm² ± 4.4 mm² and 36.3 mm² ± 4.0 mm² for the AM and PL tunnels, respectively. The total surface area occupied by both tunnels was 82.6 mm² ± 7.0 mm². In the coronal plane, tunnel orientation showed the AM tunnel was more vertical than the PL tunnel with a 10° divergence (14.8° vs. 24.1°). In the sagittal plane, both tunnels were almost parallel (29.9° and 25.4° for the AM and PL tunnels, respectively). When using anatomic aimers, the morphometric parameters of the reconstructed tibial footprint in terms of length and distances to the surrounding bony landmarks were similar to the native ACL tibial footprint. However, the native footprint width was not restored, and the surface area of the two tunnel apertures was in the lower range of the published values for the native footprint area.     

Equal tension in all four strands of a semitendinosus graft with a low profile tibial fixation device (Cobra LFD)

The article introduces a novel tibia fixation device, the Cobra Ligament Fixation Device (Cobra LFD), for anterior cruciate ligament reconstruction. The Cobra LFD has a low profile and is hooked upon the cortical bone of tibia. It is useful either for primary ACL reconstruction or for ACL revision surgery, mainly for fixation of hamstring grafts. Fixation in the cortical bone is of great importance, in particular for revision cases. Besides technical aspects, we also present the 4-year follow-up of 15 cases of ACL revision surgery, where the Cobra LFD has been used for the tibia fixation.     

Graft impingement in anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) graft impingement is one of the most troubling complications in ACL reconstruction. In the previous strategy of isometric “non-anatomical” ACL reconstruction, posterior tibial tunnel placement and notchplasty were recommended to avoid graft impingement. Recently, the strategy of ACL reconstruction is shifting towards “anatomical” reconstruction. In anatomical ACL reconstruction, the potential risk of graft impingement is higher than in non-anatomical reconstruction because the tibial tunnel is placed at a more anterior portion on the tibia. However, there have been few studies reporting on graft impingement in anatomical ACL reconstruction. This study will provide a review of graft impingement status in both non-anatomical and the more recent anatomical ACL reconstruction techniques. In conclusion, with the accurate creation of bone tunnels within ACL native footprint, the graft impingement might not happen in anatomical ACL reconstruction. For the clinical relevance, to prevent graft impingement, surgeons should pay attention of creating correct anatomical tunnels when they perform ACL reconstruction. Level of evidence IV.     

Coronal tibial anteromedial tunnel location has minimal effect on knee biomechanics

Purpose

Studies have found anatomic variation in the coronal position of the insertion site of anteromedial (AM) bundle of the anterior cruciate ligament (ACL) on the tibia, which can lead to questions about tunnel placement during ACL reconstruction. The purpose of this study was to determine how mediolateral placement of the tibial AM graft tunnel in double-bundle ACL reconstructions affects knee biomechanics.

Methods

Two different types of double-bundle ACL reconstructions were performed. The AM tibial tunnel was placed at either the medial or lateral portion of tibial AM footprint. Nine cadaveric knees were tested with the robotic/universal force-moment sensor system with the use of (1) an 89.0-N anterior tibial load at full extension (FE), 30°, 60° and 90° of knee flexion and (2) a combined 7.0-Nm valgus torque and 5.0-Nm internal tibial rotation torque at FE, 15°, 30°and 45° of knee flexion.

Results

Both medial (2.6?±?1.2 mm) and lateral (1.6?±?0.9 mm) double-bundle reconstructions reduced the anterior tibial translation (ATT) to less than the intact value (3.9?±?0.7 mm) at FE. At all other flexion angles, there was no significant different in ATT between the intact knee and the reconstructions. At FE, the ATT for the medial AM reconstruction was different from that of the lateral AM construction and closer to the intact ACL value.

Conclusion

The coronal tibial placement of the AM tunnel had only a slight effect on knee biomechanics. In patients with differing AM bundle coronal positions, the AM tibial tunnel can be placed anatomically at the native insertion site.

     

Histological changes and apoptosis of cartilage layer in human anterior cruciate ligament tibial insertion after rupture

The purpose of this study is to investigate the histological changes and apoptosis of cartilaginous layers in human anterior cruciate ligament (ACL) tibial insertion at different time periods after rupture. By using a core reamer, 35 tibial insertions of ruptured ACLs were obtained during primary ACL reconstructions (number of days after injury: 19–206 days). A histological examination was performed and a terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) staining assay was carried out to detect apoptosis. The average thickness of the cartilage layer, the glycosaminoglycan-stained area and the number of chondrocytes per millimeter decreased with time. The percentage average of TUNEL-positive chondrocytes was 42.0 ± 16.2. The histological degenerative changes of the cartilage layer in the ruptured ACL tibial insertion progressed with time, especially in the first 2 months. Moreover, chondrocyte apoptosis continued from 19 to 206 days after rupture. The results may help elucidate the etiology of the histological changes of the insertion, and may help in devising optimal treatment protocols for ACL injuries if apoptosis is controlled. Moreover, we consider that using a surviving ligament and minimizing a debridement of ACL remnant during ACL reconstruction may be important for ACL reconstruction to maintain cartilage layers in ACL insertions.     

Posterior horn instability of the medial meniscus a sign of posterior meniscotibial ligament insufficiency

Purpose  

In longstanding chronic anterior cruciate ligament (ACL) insufficiency, we identified an abnormal movement of the posterior medial meniscal horn, likely due to insufficiency of the posteromedial meniscotibial ligament. Passing from extension to flexion or vice versa, the medial posterior horn slides below the posterior rim of the tibia exposing the tibial plateau. Fixation with suture anchors of the meniscotibial ligament through a posteromedial portal restored normal meniscotibial tension and reduced instability of the meniscal posterior horn. The purpose of the present study was to present the arthroscopic features of posterior medial meniscus instability and to report results following arthroscopic repair.     

Current concepts in anatomic single- and double-bundle anterior cruciate ligament reconstruction

An anterior cruciate ligament (ACL) tear is one of the most common orthopedic sport injuries. The ACL consists of 2 functional bundles-the anteromedial and posterolateral-which are named for the position of their insertion sites on the tibia. Anatomic ACL reconstruction can be defined as the restoration of the ACL to its native dimensions, collagen orientation, and insertion sites. Some biomechanical studies have demonstrated that anatomic ACL reconstruction can restore knee motion significantly similar to that of the normal knee, as compared with traditional, nonanatomic single-bundle procedures. In vivo kinematic studies have also shown that nonanatomic single-bundle reconstruction fails to restore normal dynamic knee stability in all cases. Accurate restoration of knee kinematics with anatomic ACL reconstruction is critical to protect against the possibility that nonatomic sugical technique could result in early osteoarthritis, which is common in patients who sustain ACL tears. Surgical techniques for ACL reconstruction vary, and if different aspects of the surgery are compared for superiority (eg, single- vs double-bundle techniques), it is necessary that both procedures meet criteria to be designated as "anatomic." By emphasizing the importance of restoring the native anatomy of the knee, surgeons can give their patients the best chance at restoration of joint function and preservation of long-term knee health.     

Insertion of autologous tendon grafts to the bone: a histological and immunohistochemical study of hamstring and patellar tendon grafts

This study examined the structure of the insertion of autologous tendon grafts used for anterior cruciate ligament reconstruction. Biopsy specimens of the femoral ¶and tibial bone graft interface were obtained at revision surgery in 14 patients (6 with hamstring grafts, 8 with a patella tendon graft). The specimens were analyzed by light microscopy and immunohistochemistry (confirming type I, type II, and type III collagen). The insertions of hamstring autografts to the bone tunnel have three characteristic histological zones. Zone 1 is composed of the dense connective tissue of the graft. The collagen fibers of the graft enter the bone under oblique angles. Zone 2 is composed of woven bone with ¶a sharp transition to the lamellar bone of the tibia (zone 3). Immunohistochemistry revealed the presence of type I and type III collagen within the dense connective tissue of the graft. The woven and lamellar bone showed positive immunostaining for antibodies against type I collagen only. This structure resembled a fibrous ligament or tendon insertion. In the majority of patients with a patella tendon graft the structure of the insertion resembled a chondral enthesis. The chondral insertion of the graft to the bone is composed of four characteristic zones. Between the dense connective tissue of the graft (zone 1) and bone (zone 4) there is a zone of fibrocartilage (zone 2). Close to the bone the fibrocartilage is mineralized (zone 3). Within the fibrocartilage the immunohistochemical analysis confirmed type II collagen. This structure resembled the chondral enthesis of the normal anterior cruciate ligament. However, in cases in which the distal bone bloc has been fixated outside the tibial tunnel, the tibial insertion of the patellar tendon graft resembled a fibrous insertion. While both types of tendon grafts heal to the bone of femur and tibia, the insertion of patella tendon grafts healing by bone plug incorporation resembles the chondral insertion of the normal anterior cruciate ligament and may have a more physiological connection to the bone than hamstring grafts.