Imaging of Noncontact Anterior Cruciate Ligament Injuries and Associated Bone Marrow Contusion Patterns

Anterior cruciate ligament (ACL) tears are commonly associated with bone contusions. Bone contusions can lend important insight into increased risk for more subtle concurrent injuries based on common injury mechanisms and patterns, as higher energy trauma has been tied to patterns of specific bone contusions and concomitant injuries. Lateral compartment contusions are most common and occur in pivot shift injuries. Medial compartment contusions may represent a contrecoup mechanism after the initial lateral injuries. Patellotibial contusions require axial loading but are also typically seen in conjunction with lateral and medial compartment contusions. The differences in ACL injury mechanics and physiology as shown by imaging contusion patterns can help clinicians better identify and treat the concurrent associated injuries.

Distribution of Bone Contusion Patterns in Acute Noncontact Anterior Cruciate Ligament–Torn Knees

Background: Bone contusions are commonly observed on magnetic resonance imaging (MRI) in individuals who have sustained a noncontact anterior cruciate ligament (ACL) injury. Time from injury to image acquisition affects the ability to visualize these bone contusions, as contusions resolve with time. Purpose: To quantify the number of bone contusions and their locations (lateral tibial plateau [LTP], lateral femoral condyle [LFC], medial tibial plateau [MTP], and medial femoral condyle [MFC]) observed on MRI scans of noncontact ACL-injured knees acquired within 6 weeks of injury. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We retrospectively reviewed clinic notes, operative notes, and imaging of 136 patients undergoing ACL reconstruction. The following exclusion criteria were applied: MRI scans acquired beyond 6 weeks after injury, contact ACL injury, and previous knee trauma. Fat-suppressed fast spin-echo T2-weighted MRI scans were reviewed by a blinded musculoskeletal radiologist. The number of contusions and their locations (LTP, LFC, MTP, and MFC) were recorded. Results: Contusions were observed in 135 of 136 patients. Eight patients (6%) had 1 contusion, 39 (29%) had 2, 41 (30%) had 3, and 47 (35%) had 4. The most common contusion patterns within each of these groups were 6 (75%) with LTP for 1 contusion, 29 (74%) with LTP/LFC for 2 contusions, 33 (80%) with LTP/LFC/MTP for 3 contusions, and 47 (100%) with LTP/LFC/MTP/MFC for 4 contusions. No sex differences were detected in contusion frequency in the 4 locations ( P > .05). Among the participants, 50 (37%) had medial meniscal tears and 52 (38%) had lateral meniscal tears. Conclusion: The most common contusion patterns observed were 4 locations (LTP/LFC/MTP/MFC) and 3 locations (LTP/LFC/MTP).

Evaluation of Anterolateral Ligament Healing After Anatomic Anterior Cruciate Ligament Reconstruction

Background: Few studies have reported the healing process of anterolateral ligament (ALL) injuries. Purpose/Hypothesis: This study investigated the healing status of ALL injuries after primary anterior cruciate ligament (ACL) reconstruction (ACLR). Additionally, we investigated the association between the healing status of ALL injuries and associated lesions such as osseous lesions and meniscal tears occurring at the time of an ACL rupture. We hypothesized that acute ALL injuries show a high rate (more than two-thirds) of healing at the 1-year follow-up after ACLR and that concomitant lesions observed at the time of an ACL rupture affect the healing status of the ALL. Study Design: Case-control study; Level of evidence, 3. Methods: We retrospectively investigated patients with ALL injuries who underwent primary ACLR between March 2015 and February 2017. Using magnetic resonance imaging (MRI), we evaluated the features of ALL injuries and concomitant lesions, and MRI was performed at the 1-year follow-up to assess the healing status of the ALL. We investigated the association between the healing status of the ALL and concomitant lesions observed at the time of an ACL rupture. A subjective assessment was performed using the Lysholm score, International Knee Documentation Committee subjective score, and Tegner activity scale. Objective tests included an isokinetic strength assessment and functional performance testing. Results: With respect to the severity of ALL injuries, of 54 patients, a complete rupture occurred in 16 (29.6%) of the 54 patients and a partial rupture in 38 (70%). A significant association was observed between the severity of ALL injuries and bone contusions (lateral tibial plateau and medial tibial plateau [MTP]) and meniscus ramp lesions (Fisher exact test: P = .023, .012, and .023, respectively). Good and partial healing of the ALL occurred in 16 (29.6%) and 23 (42.6%) of 54 patients, respectively. Scar formation occurred in 12 (22.2%), and nonvisualization of the ALL was observed in 3 (5.6%) of 54 patients. Poor healing of the ALL was associated with preoperative MTP bone contusions and a high-grade pivot shift. Multivariate analysis showed that an MTP bone contusion was an independent risk factor associated with poor healing of the ALL. Among the functional tests performed, significant differences were observed between the good and poor healing groups with respect to the carioca test ( P = .039). The good healing group (n = 16) showed a negative pivot shift at the last follow-up, whereas 5 (13.2%) of the patients from the poor healing group (n = 38) showed a positive pivot shift, including 2 (5.3%) with a high-grade pivot shift. Conclusion: Approximately 70% of acute ALL injuries showed poor healing at the 1-year follow-up. Poor healing of ALL injuries was significantly associated with preoperative MTP bone contusions and a high-grade pivot shift. Therefore, a careful assessment of posteromedial bone contusions at the time of an ACL rupture is warranted, particularly in patients with a high-grade pivot shift.

Gender Differences in Intra-articular and Extra-articular Injuries Associated with Acute Anterior Cruciate Ligament Ruptures

Females are well known to have a two to nine times increase in relative risk of anterior cruciate ligament (ACL) rupture as compared with males. However, there is limited literature available regarding the rates of associated intra-articular and extra-articular injuries associated with ACL ruptures. The purpose of this study was to investigate the gender differences in intra-articular and extra-articular injuries associated with ACL ruptures in an acute setting. Therefore, in the cross-sectional study of consecutive patients, all patients who underwent ACL reconstruction in a single institution were identified if they had a magnetic resonance imaging (MRI) done within 6 weeks of sustaining the injury and if their injury was sustained during sports activities. Patients were excluded if they had prior surgery in the affected knee, including revision ACL reconstructions. A musculoskeletal MRI radiologist blinded to the study's purpose then reported the incidence of ligamentous injuries, meniscal tears, chondral injuries, and bone contusions. Correlations were then performed between the patient's gender and the prevalence of these associated injuries. A total of 304 patients were included in the study. Comparison between males and females revealed no gender differences for the associated intra-articular and extra-articular injuries of acute ACL rupture. These include the prevalence of medial collateral ligament injuries (p = 0.118), lateral collateral ligament injuries (p = 0.445), medial meniscus injuries (p = 0.874), lateral meniscus injuries (p = 0.612), chondral injuries (p = 0.331), medial (p = 0.143) and lateral femoral condyle bone contusions (p = 0.246), and medial (p = 0.787) and lateral tibial plateau bone contusions (p = 0.765). In conclusion, males and females have similar rates of associated intra-articular and extra-articular injuries after ACL rupture in the acute setting. These include associated collateral ligament injuries, meniscal injuries, chondral injuries, and bone contusions. The level of evidence is Level II.

Bone Contusion on the Medial Compartment is a Predictive Factor for more Associated Injuries After ACL Rupture

Objectives: Determine the frequency of bone contusion and associated injuries, observed in patients with anterior cruciate ligament (ACL) rupture. Methods: Seventy two patients with an ACL rupture were enrolled in our prospective study. Magnetic resonance images (MRI) and arthroscopic findings of all patients were examined in order to detect bone contusions and associated injuries, such as meniscal lesions and medial collateral ligament (MCL) injury. ACL rupture and meniscal lesions were also verified with knee arthroscopy. Correlation between bone contusions and meniscal lesions or MCL injury was performed. Statistical packet STATA 8.0 was used for data analysis and significance was set at p<0.05. Results: Fifty eight (80.5%) patients presented with associated bone contusions observed on magnetic resonance imaging. Lateral aspect of the tibia plateau (71%) and lateral femoral condyle (69%) were the most common sites with contusions. Medial compartment was associated with contusions of medial aspect of the tibia plateau and medial femoral condyle in 25% and 22% of patients respectively. The frequency of lateral meniscus (p = 0.022), medial meniscus (p = 0.036) and MCL (p = 0.05) injuries, significantly increased in patients with bone contusions of medial and lateral compartments compared to those with bone contusions on lateral only compartment or without bone contusions. Conclusion: Bone contusion on the medial compartment is a predictive factor for more associated injuries, seen after ACL rupture and it suggest a higher energy trauma.