Incidence and location of bone bruises after acute posterior cruciate ligament injury

BACKGROUND: In patients suffering from an anterior cruciate ligament injury, the incidence and location of bone bruises are well documented. This study reports data regarding bone bruises after acute posterior cruciate ligament injury. HYPOTHESIS: Bone bruises associated with posterior cruciate ligament injury are common, and their location differs from those seen with anterior cruciate ligament injury. STUDY DESIGN: Retrospective cohort study. METHODS: Thirty-five consecutive patients were identified as having a grade II or III posterior cruciate ligament tear, with an intact anterior cruciate ligament, in which a magnetic resonance imaging scan had been obtained within 20 days of injury. Magnetic resonance imaging scans were reviewed to document bone bruises, associated medial or lateral ligamentous injury, and meniscal and chondral abnormalities. RESULTS: Of the 35 patients, 29 (83%) had a bone bruise in at least one location. Bone bruises were found throughout the joint, more widely dispersed than is commonly seen with anterior cruciate ligament injury. Also, 29 patients had magnetic resonance imaging findings of associated ligamentous injury. Lateral bone bruises were associated with medial collateral ligament injury, whereas medial bone bruises correlated with posterolateral injury. CONCLUSIONS: The incidence of bone bruises associated with posterior cruciate ligament injury is similar to that seen with anterior cruciate ligament injury. Their location is more widely dispersed. The location of a bone bruise should lead to careful magnetic resonance imaging inspection and physical examination for ligamentous injury to the opposite side of the joint. Truly isolated posterior cruciate ligament injuries are rare, as most occur with osseous and some degree of associated ligamentous injury.     

In vivo elongation of the anterior cruciate ligament and posterior cruciate ligament during knee flexion

BACKGROUND: Most knowledge regarding cruciate ligament function is based on in vitro experiments. PURPOSE: To investigate the in vivo elongation of the functional bundles of the anterior cruciate ligament and posterior cruciate ligament during weightbearing flexion. HYPOTHESIS: The biomechanical role of functional bundles of the anterior cruciate ligament and posterior cruciate ligament under in vivo loading is different from that measured in cadavers. STUDY DESIGN: In vivo biomechanical study. METHODS: Elongation of the anterior cruciate ligament and posterior cruciate ligament was measured during a quasi-static lunge using imaging and 3-dimensional computer-modeling techniques. RESULTS: The anterior-medial bundle of the anterior cruciate ligament had a relatively constant length from full extension to 90 degrees of flexion. The posterior-lateral bundle of the anterior cruciate ligament decreased in length with flexion. Both bundles of the posterior cruciate ligament had increased lengths with flexion. CONCLUSION: The data did not demonstrate the reciprocal function of the 2 bundles of the anterior cruciate ligament or the posterior cruciate ligament with flexion observed in previous studies. Instead, the data suggest that there is a reciprocal function between the anterior cruciate ligament and posterior cruciate ligament with flexion. The anterior cruciate ligament plays a more important role in low-flexion angles, whereas the posterior cruciate ligament plays a more important role in high flexion. CLINICAL RELEVANCE: Understanding the biomechanical role of the knee ligaments in vivo is essential to reproduce the structural behavior of the ligament after injury (especially for 2-bundle reconstructions) and thus improve surgical outcomes.     

Advanced MR imaging of the cruciate ligaments

The anterior and posterior cruciate ligaments are crucial stabilizers of the knee. These ligaments are named by the location of their tibial attachments. Each ligament is composed of separate functional bundles that differ in size but are equally important in function. MR imaging is accurate and sensitive, making it the imaging technique of choice for evaluating these ligaments. Acute and chronic injuries involving the cruciate ligaments have typical appearances and associated findings. MR imaging interpretation must take into account atypical injuries and imaging pitfalls. Knowledge of normal ligament reconstruction techniques allows differentiation of the normal postoperative appearance from reconstruction failure and complications. Ligament reconstruction techniques, complications, and appearances are reviewed in this article.     

MR imaging of anterior cruciate ligament reconstruction graft

OBJECTIVE. The objective was to determine the MR imaging findings that differentiate intact anterior cruciate ligament reconstruction graft, partial-thickness tear, and full-thickness tear, using arthroscopy as the gold standard. MATERIALS AND METHODS. Sixteen consecutive MR imaging examinations were retrospectively and independently evaluated by two musculoskeletal radiologists for primary signs (graft signal, orientation, fiber continuity, complete discontinuity, and thickness) and secondary signs (anterior tibial translation, uncovered posterior horn lateral meniscus, posterior cruciate ligament hyperbuckling, and abnormal posterior cruciate ligament line) of anterior cruciate ligament reconstruction graft tear in 15 patients with follow-up arthroscopy. Results were compared with arthroscopy, and both receiver operating characteristic curves and kappa values for interobserver variability were calculated. RESULTS. Arthroscopy revealed four full-thickness graft tears, seven partial-thickness tears, and five intact grafts. Of the primary signs, graft fiber continuity in the coronal plane and 100% graft thickness in the sagittal or coronal plane were most valuable in excluding full-thickness tear. Complete discontinuous graft in the coronal plane also was valuable in diagnosis of full-thickness tear. Of the secondary signs, anterior tibial translation and uncovered posterior horn lateral meniscus assisted in differentiating graft tear (partial or full thickness) from intact graft. The other primary and secondary signs were less valuable. Kappa values were highest for graft fiber continuity and graft discontinuity in the coronal plane. CONCLUSION. Full-thickness anterior cruciate ligament graft tear can be differentiated from partial-thickness tear or intact graft by evaluating for graft fiber continuity (coronal plane), complete graft discontinuity (coronal plane), and graft thickness (coronal or sagittal plane).     

Computed tomography of the anterior cruciate ligament

The anterior cruciate ligaments of 20 patients with suspected pathology in one ligament were studied by thin-section computed tomography (CT) and reformating techniques. In 19 patients, the suspect anterior cruciate ligament was abnormal and this was confirmed by subsequent arthroscopy or arthrotomy in thirteen. Thin-section CT and reformatting techniques provide a useful means of non-invasively imaging the anterior cruciate ligament.     

Anatomic single- and double-bundle anterior cruciate ligament reconstruction, part 2: clinical application of surgical technique

The anterior cruciate ligament has been and is of great interest to scientists and orthopaedic surgeons worldwide. Anterior cruciate ligament reconstruction was initially performed using an open approach. When the approach changed from open to arthroscopic reconstruction, a 2- and, later, 1-incision technique was applied. With time, researchers found that traditional arthroscopic single-bundle reconstruction did not fully restore rotational stability of the knee joint and a more anatomic approach to reconstruct the anterior cruciate ligament has been proposed. Anatomic anterior cruciate ligament reconstruction intends to replicate normal anatomy, restore normal kinematics, and protect long-term knee health. Although double-bundle anterior cruciate ligament reconstruction has been shown to result in better rotational stability in both biomechanical and clinical studies, it is vital to differentiate between anatomic and double-bundle anterior cruciate ligament reconstruction. The latter is merely a step closer to reproducing the native anatomy of the anterior cruciate ligament; however, it can still be done nonanatomically. To evaluate the potential benefits of reconstructing the anterior cruciate ligament in an anatomic fashion, accurate, precise, and reliable outcome measures are needed. These include, for example, T2 magnetic resonance imaging mapping of cartilage and quantification of graft healing on magnetic resonance imaging. Furthermore, there is a need for a consensus on which patient-reported outcome measures should be used to facilitate homogeneous reporting of outcomes.     

Kinematic MR imaging of the knee

This is an overview of the "cine magnetic resonance (MR) imaging" system and rapid (ultra-fast) MR imaging of the knee for evaluation of injury of the cruciate ligament including its function during flexion and extension. Cine MR imaging using a gating system and a cine acquisition delineates alterations of the signal and shape of the cruciate ligaments and menisci. Rapid (ultra-fast) MR images with a single acquisition time of half second or less using a mobile knee brace and a flexible surface coil has enabled rapid acquisition of moving knee motion in multi-image frames. Visualization of the moving normal and torn anterior cruciate ligaments indicates that kinematic MR imaging of the moving knee is advantageous in evaluating the continuity and tension in the cruciate ligaments.     

Magnetic resonance diagnosis of meniscal tears in patients with acute anterior cruciate ligament tears

OBJECTIVE: To evaluate the accuracy of magnetic resonance imaging in the diagnosis of meniscal tear in patients with acute anterior cruciate ligament tears. METHODS: Magnetic resonance images obtained from 41 patients imaged within 6 weeks of injury who had acute anterior cruciate ligament tears identified at arthroscopy were retrospectively reviewed for meniscal tear. RESULTS: With MR imaging the sensitivity, specificity and accuracy for diagnosing meniscal tears in the presence of acute anterior cruciate ligament tears were 71%, 93%, and 88%; for the lateral meniscal tears were 57%, 100% and 85%; and for the medial meniscal tears were 100%, 88%, 90%. All false negative cases (n = 6) involved the posterior horn of the lateral meniscus. CONCLUSION: In the presence of acute anterior cruciate ligament tears, MRI imaging has relatively low sensitivity for detecting meniscal tears due to missed tears in the lateral meniscus.     

The 6 degrees of freedom kinematics of the knee after anterior cruciate ligament deficiency: an in vivo imaging analysis

BACKGROUND: Previous studies of knee joint function after anterior cruciate ligament deficiency have focused on measuring anterior-posterior translation and internal-external rotation. Few studies have measured the effects of anterior cruciate ligament deficiency on 6 degrees of freedom knee kinematics in vivo. OBJECTIVE: To measure the 6 degrees of freedom knee kinematics of patients with anterior cruciate ligament deficiency. STUDY DESIGN: Controlled laboratory study. METHODS: The knee joint kinematics of 8 patients with unilateral anterior cruciate ligament rupture was measured during a quasi-static lunge. Kinematics was measured from full extension to 90 degrees of flexion using imaging and 3-dimensional modeling techniques. The healthy, contralateral knee of each patient served as a control. RESULTS: Anterior cruciate ligament deficiency caused a statistically significant anterior shift (approximately 3 mm) and internal rotation of the tibia (approximately 2 degrees ) at low flexion angles. However, ligament deficiency also caused a medial translation of the tibia (approximately 1 mm) between 15 degrees and 90 degrees of flexion. CONCLUSION: The medial shift of the tibia after anterior cruciate ligament deficiency might alter contact stress distributions in the tibiofemoral cartilage near the medial tibial spine. These findings correlate with the observation that osteoarthritis in patients with anterior cruciate ligament injuries is likely to occur in this region. CLINICAL RELEVANCE: The data from this study suggest that future anterior cruciate ligament reconstruction techniques should reproduce not only anterior stability but also medial-lateral stability.     

Acute grade III medial collateral ligament injury of the knee associated with anterior cruciate ligament tear. The usefulness of magnetic resonance imaging in determining a treatment regimen

BACKGROUND: The appropriate management of acute grade III medial collateral ligament injury when it is combined with a torn anterior cruciate ligament has not been determined. HYPOTHESIS: Magnetic resonance imaging grading of grade III medial collateral ligament injury in patients who also have anterior cruciate ligament injury correlates with the outcome of their nonoperative treatment. STUDY DESIGN: Prospective cohort study. METHODS: Seventeen patients were first treated nonoperatively with bracing. Eleven patients with restored valgus stability received anterior cruciate ligament reconstruction only, and six with residual valgus laxity also received medial collateral ligament surgery. RESULTS: Magnetic resonance imaging depicted complete disruption of the superficial layer of the medial collateral ligament in all 17 patients and disruption of the deep layer in 14. Restoration of valgus stability was significantly correlated with the location of superficial fiber damage. Damage was evident over the whole length of the superficial layer in five patients, and all five patients had residual valgus laxity despite bracing. Both groups had good-to-excellent results 5 years later. CONCLUSIONS: Location of injury in the superficial layer may be useful in predicting the outcome of nonoperative treatment for acute grade III medial collateral ligament lesions combined with anterior cruciate ligament injury.     

Surgical treatment of acute and chronic anterior and posterior cruciate ligament and lateral side injuries of the knee

Combined anterior cruciate ligament, posterior cruciate ligament, and lateral-sided injuries of the knee most often occurs secondary to a forced varus moment or after knee dislocation. Management controversies include the optimal timing of surgery, operative techniques, and postoperative rehabilitation. Recent systematic literature reviews have demonstrated higher rates of failure with repair of the lateral and posterolateral corner structures, as opposed to reconstruction. However, the ideal ligament reconstruction techniques remain unclear. This chapter will review the combined anterior cruciate ligament/posterior cruciate ligament/lateral-sided injury pattern, including the physical examination findings, imaging, timing of surgery, graft selection, operative techniques, and postoperative rehabilitation protocols.     

Correlation of anthropometric measurements, strength, anterior cruciate ligament size, and intercondylar notch characteristics to sex differences in anterior cruciate ligament tear rates

We performed a prospective study based on the hypothesis that physiologic differences exist between men and women in strength after adjustments for body weight; that the size of the anterior cruciate ligament is proportionate to the strength of its antagonists, the quadriceps muscles; and that women have a relatively small anterior cruciate ligament, thus predisposing them to a disproportionate number of anterior cruciate ligament injuries. One hundred matched high school basketball players, 50 male and 50 female, were evaluated with anthropometric measurements, body fat analysis, muscle strength evaluation, and magnetic resonance imaging measurements of the intercondylar notch and cross-sectional area of the anterior cruciate ligament at the outlet. The male players were taller and heavier than their female counterparts, although they had 11% less body fat. Male players had statistically greater quadriceps and hamstring muscle strength than female players, even when adjustments were made for body weight. With adjustments for body weight, the size of the anterior cruciate ligament in girls was found to be statistically smaller than in boys. There was no statistically significant difference in the notch width index between the sexes. The study data support our hypothesis that sex differences in anterior cruciate ligament tear rates are caused primarily by several interrelated intrinsic factors. Most importantly, stiffness and muscular strength increase stress on the anterior cruciate ligament in female athletes. The anterior cruciate ligament, when adjustments have been made for body weight, is smaller in female athletes, and therefore, probably does not compensate for the lack of stiffness and strength.     

The effect of anterior cruciate ligament deficiency on the in vivo elongation of the medial and lateral collateral ligaments

BACKGROUND: Although anterior cruciate ligament deficiency has been shown to lead to joint degeneration, few quantitative data have been reported on its effect on soft tissue structures surrounding the knee joint. HYPOTHESIS: Anterior cruciate ligament deficiency will alter the deformation of both collateral ligaments during in vivo weight-bearing knee function from 0 degrees to 90 degrees. STUDY DESIGN: Controlled laboratory study. METHODS: Six patients who had acute anterior cruciate ligament injury in 1 knee with the contralateral side intact participated in this study. Using magnetic resonance and dual orthogonal fluoroscopic imaging techniques, we measured the length of the fiber bundles of the superficial medial collateral ligament, deep medial collateral ligament, and lateral collateral ligament of the 6 patients; the healthy contralateral knee of each patient served as a control. RESULTS: Anterior cruciate ligament injury caused a significant elongation of the fiber bundles of the superficial and deep medial collateral ligament at every flexion angle. In contrast, the lateral collateral ligament fiber bundles shortened after anterior cruciate ligament injury. CONCLUSION: The altered deformations of the collateral ligaments associated with the changes in tibiofemoral joint kinematics after anterior cruciate ligament injury demonstrate that deficiency of 1 of the knee joint structures upsets the in vivo knee homeostasis. CLINICAL RELEVANCE: Restoring normal knee kinematics after anterior cruciate ligament reconstruction is critical to restore the normal function of the collateral ligaments.     

Anterior cruciate ligament reconstruction: evaluation with MR imaging

Fifty magnetic resonance (MR) imaging examinations were performed in 37 patients after arthroscopic anterior cruciate ligament (ACL) reconstruction with patellar bone-tendon-tibial bone autografts. T1-weighted sagittal and axial images were obtained. In 34 patients with clinically stable ACL autografts, 43 of 47 MR examinations demonstrated a well-defined, intact ACL autograft. All three patients with ACL laxity failed to demonstrate a well-defined autograft, for an overall correlation between MR imaging and clinical examination results of 92%. Of the 12 patients who underwent second-look arthroscopy, 100% correlation was present between MR imaging and arthroscopic results. As in the nonreconstructed knee, buckling of the posterior cruciate ligament was suggestive of ACL laxity. MR imaging also documented optimum placement of bone tunnels in the femur and tibia. MR imaging has proved to be an excellent noninvasive imaging modality for evaluating ACL reconstruction, while also providing ancillary information about the postoperative knee.     

Tears of the anterior cruciate ligament and menisci of the knee: MR imaging evaluation

In 242 of 3,000 patients who underwent magnetic resonance (MR) imaging of the knee between September 1986 and August 1987, original MR imaging reports were compared with subsequent arthroscopic reports to determine the value of MR imaging in the evaluation of suspected meniscal and complete tears of the anterior cruciate ligament. The overall accuracy for the menisci was 93% (sensitivity, 95%; specificity, 91%) with a false-negative rate of 4.8%. For the anterior cruciate ligament the overall accuracy was 95%. T2-weighted sequences were associated with greater sensitivity, specificity, and accuracy than were T1 sequences; the false-negative rate was 0% in the T2-weighted group. MR imaging of the knee is an extremely accurate means for noninvasive assessment of the integrity of the menisci and anterior cruciate ligament, and the accuracy exceeds that usually reported for arthrography.     

Risk of tearing the intact anterior cruciate ligament in the contralateral knee and rupturing the anterior cruciate ligament graft during the first 2 years after anterior cruciate ligament reconstruction: a prospective MOON cohort study

BACKGROUND: The risk of tear of the intact anterior cruciate ligament in the contralateral knee after anterior cruciate ligament reconstruction of the opposite knee and the incidence of rupturing the anterior cruciate ligament graft during the first 2 years after surgery have not been extensively studied in a prospective manner. Clinicians have hypothesized that the opposite normal knee is at equal or increased risk compared with the risk of anterior cruciate ligament graft rupture in the operated knee. HYPOTHESIS: The risk of anterior cruciate ligament graft rupture and contralateral normal knee anterior cruciate ligament rupture at 2-year follow-up is equal. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: The Multicenter Orthopaedic Outcome Network (MOON) database of a prospective longitudinal cohort of anterior cruciate ligament reconstructions was used to determine the number of anterior cruciate ligament graft ruptures and tears of the intact anterior cruciate ligament in the contralateral knee at 2-year follow-up. Two-year follow-up consisted of a phone interview and review of operative reports. RESULTS: Two-year data were obtained for 235 of 273 patients (86%). There were 14 ligament disruptions. Of these, 7 were tears of the intact anterior cruciate ligament in the contralateral knee (3.0%) and 7 were anterior cruciate ligament graft failures (3.0%). CONCLUSION: The contralateral normal knee anterior cruciate ligament is at a similar risk of anterior cruciate ligament tear (3.0%) as the anterior cruciate ligament graft after primary anterior cruciate ligament reconstruction (3.0%).     

Chronic anterior cruciate ligament tears and associated meniscal and traumatic cartilage lesions: evaluation with morphological sequences at 3.0 T

Purpose  

To investigate the diagnostic efficacy of morphological sequences at 3.0 T MR imaging in detecting anterior cruciate ligament (ACL), meniscal pathology and traumatic cartilage legions in young patients with chronic deficient anterior cruciate ligament knees.     

Magnetic Resonance Imaging of Cruciate Ligament Injuries of the Knee

The anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) are important stabilizers of the knee. These ligaments are commonly injured in sports and motor vehicle accidents. An accurate diagnosis of cruciate ligament injuries is vital in patient care. Magnetic resonance imaging (MRI) can diagnose cruciate ligament injuries with high accuracy. The imaging diagnosis should be based on primary signs, although the secondary signs are sometimes useful, particularly in chronic cases. The detection of associated injuries of other structures of the knee, including menisci, collateral ligaments, cartilage, and bone, are also important. Accurate interpretation of the MRI examination requires a meticulous MRI technique, knowledge of the imaging anatomy, and understanding of the lesion appearance. This pictorial essay reviews the MRI appearance of normal and injured cruciate ligaments. Mechanisms of injury, primary and secondary MRI signs, and associated abnormalities are discussed.     

膝关节前交叉韧带MR扫描方式的研究

目的：探讨前交叉韧带MRI最佳的扫描方式,提高前交叉韧带MR图像的显示程度。方法：回顾性分析100例前交叉韧带MRI图像。每住受检者都按两种不同扫描方式进行扫描,第一组：斜矢状面以轴面定位像进行扫描;第二组：斜矢状面在第一组定位方式基础上,再在冠状面上按前交叉韧带走行倾斜角度进行扫描,观察两组前交叉韧带MR图像的显示情况,将所得前交叉韧带图像分为可全程显示、可分段显示、不显示三种,最后将统计出的数据进行分析。结果：第一种扫描方式全程显示70例（70／100）、分段显示25例（25／100）、不显示5例（5／100）;第二种扫描方式全程显示95例（95／100）、分段显示5例（5／100）、不显示0例（0／100）。结论：两种扫描方式前交叉韧带的显示程度差异有显著性意义（P〈0．01）,第二种扫描方式对前交叉韧带的显示情况良好,是一种较为理想的扫描方式,能显著提高前交叉韧带的显示率。