Excessive Knee Internal Rotation during Grand Plié in Classical Ballet Female Dancers

Classical ballet dancers are exposed daily to physically demanding movements. Among these, the Grand Plié stands out for its biomechanical complexity, particularly the stress applied to the knee joint. This study investigates the knee kinematics of healthy professional classical ballet dancers performing the Grand Plié. Twenty dancers were evaluated with a motion analysis system using a marker-based protocol. Before measurements, the self-reported Global Knee Functional Assessment Scale was delivered for the knees' functional ability, and the passive range of knee motion was also assessed. The average score on the Global Knee Functional Assessment Scale was 94.65 ± 5.92. During a complete circle of the Grand Plié movement, executed from the upright position, the average maximum internal rotation of the knee joint was 30.28° ± 6.16°, with a simultaneous knee flexion of 134.98° ± 4.62°. This internal rotation observed during knee flexion exceeds the typical range of motion for the joint, suggesting a potential risk for knee injuries, such as meniscal tears. The findings provide an opportunity for future kinematic analysis research, focusing on the movement of the Grand Plié and other common ballet maneuvers. These data have the potential to yield valuable information about the knee kinematics concerning meniscus damage.

Shear wave elastography demonstrates different material properties between the medial collateral ligament and anterolateral ligament

BACKGROUND

Anterolateral ligament and medial collateral ligament injuries could happen concomitantly with anterior cruciate ligament ruptures. The anterolateral ligament is injured more often than the medial collateral ligament during concomitant anterior cruciate ligament ruptures although it offers less restraint to knee movement. Comparing the material properties of the medial collateral ligament and anterolateral ligament helps improve our understanding of their structure-function relationship and injury risk before the onset of injury.

METHODS

Eight cadaveric lower extremity specimens were prepared and mechanically tested to failure in a laboratory setting using a hydraulic platform. Measurements of surface strains of superficial surface of each medial collateral ligament and anterolateral ligament specimen were found using three-dimensional digital image correlation. Ligament stiffness was found using ultrasound shear-wave elastography. t-tests were used to assess for significant differences in strain, stress, Young's modulus, and stiffness in the two ligaments.

FINDINGS

The medial collateral ligament exhibited greater ultimate failure strain along its longitudinal axis (p = 0.03) and Young's modulus (p < 0.0018) than the anterolateral ligament. Conversely, the anterolateral ligament exhibited greater ultimate failure stress than the medial collateral ligament (p < 0.0001). Medial collateral ligament failure occurred mostly in the proximal aspect of the ligament, while most anterolateral ligament failure occurred in the distal or midsubstance aspect (P = 0.04).

INTERPRETATION

Despite both being ligamentous structures, the medial collateral ligament and anterolateral ligament exhibited separate material properties during ultimate failure testing. The weaker material properties of the anterolateral ligament likely contribute to higher rates of concomitant injury with anterior cruciate ligament ruptures.

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.

Magnetic resonance imaging (MRI) and Computed topography (CT) analysis of Schatzker type IV tibial plateau fracture revealed possible mechanisms of injury beyond varus deforming force

BACKGROUND

Schatzker type IV tibial plateau fractures (type IV TPFs) are known for complex fracture morphology and high frequency of knee subluxation. Varus deforming force has been believed to be the cause but which fails to explain the lateral tibial plateau comminution and the lateral femoral condyle bone edema observed on injury MRI. The purpose of this study is to further explore the mechanisms of injury of type IV TPFs by synthetically analysing the information obtained from MRI and CT of a cohort of patients.

METHODS

Between 2010 and 2019, 49 type IV TPFs were surgically treated in our hospital. The patients with complete preoperative CT and MRI were enrolled. They were classified according to OTA/AO and Luo's updated three-column classification (uTCC) after fracture morphology analysing and measuring. Then the injuries of cruciate/collateral ligaments and bone contusion were studied on MRI. The discrepancy between obvious fracture and occult bone contusion/soft tissue disruption among the groups of uTCC were compared and analysed.

RESULTS

Thirty patients were eligible for this study. Under uTCC system, all the cases were caused by varus force according to the tibial plateau angle and were classified into three groups of uTCC referring the posterior tibial slope angle: 4 were into hyperextension-varus, 21 into the extension-varus and 5 into the flexion-varus group. Fracture morphology analysis found in the extension-varus group, there were two distinct subgroups: OTA/AO 41B1.2 (medial+posteromedial columns disruption) and 41B3.3f (41B1.2 +posterolateral column disruption). Injury MRI revealed 28 of the 30 cases had more than 2 ligamentous injuries. The incidences of anterior and posterior cruciate injury were 96.7% and 43.3% respectively while 70% for medial collateral ligament (MCL). Eighteen out of 30 demonstrated apparent lateral femoral condyle bone contusion sign. Chi-square analysis found in the extension-varus group, the posterolateral column comminution was closely associated with lateral femoral condylar contusion (p<0.05) and MCL injuries (p<0.05). This finding and the absence of medial femoral condylar contusion was unlikely caused by uTCC proposed varus deforming force.

CONCLUSION

In contrast to varus impaction, some type IV TPFs was probably caused by valgus or rotation force.

Bone Marrow Edema: Overview of Etiology and Treatment Strategies

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Bone marrow edema (BME) is a nonspecific but relevant finding, usually indicating the presence of an underlying pathology.

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The gold standard technique for detecting BME is magnetic resonance imaging (MRI), as it allows for a correct diagnosis to be made, which is extremely important given the heterogeneity of BME-related diseases.

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Depending on the severity of painful symptomatology and the MRI evidence, different treatment strategies can be followed: physical modalities, pharmacological options, and surgical therapy.

Five Overlooked Injuries on Knee MRI

This article highlights five knee injuries that, in the author's experience, are commonly overlooked by readers inexperienced in knee MRI: ramp lesions, meniscocapsular tears, meniscal root ligament tears, posterior capsular ligament tears, and partial anterior cruciate ligament tear. While these injuries are readily apparent when the images are assessed for the given abnormality, the author's belief is that these may be overlooked because either the injury is not considered, or the affected area is not closely inspected. While these injuries may not alter immediate clinical management or require surgical intervention, they may, nevertheless, result in patient symptoms and may potentially increase the risk of further knee injury. Further, these injuries are difficult to recognize clinically and arthroscopically. In this review, we present these five injuries, emphasising relevant anatomy, normal MRI appearances, common injury patterns, and tips to avoid their being overlooked. Routine review of these areas when interpreting knee MRI, with additional imaging as necessary, will allow these injuries to be recognized more regularly.

Edema-like marrow signal intensity: a narrative review with a pictorial essay

The term edema-like marrow signal intensity (ELMSI) represents a general term describing an area of abnormal signal intensity at MRI. Its appearance includes absence of clear margins and the possibility of exceeding well-defined anatomical borders (for example, physeal scars). We can define "ELMSI with unknown cause" an entity where the characteristic MR appearance is associated with the absence of specific signs of an underlying condition. However, it is more often an important finding indicating the presence of an underlying disease, and we describe this case as "ELMSI with known cause." It presents a dynamic behavior and its evolution can largely vary. It initially corresponds to an acute inflammatory response with edema, before being variably replaced by more permanent marrow remodeling changes such as fibrosis or myxomatous connective tissue that can occur over time. It is important to study ELMSI variations over time in order to evaluate the activity state and therapeutic response of an inflammatory chronic joint disease, the resolution of a trauma, and the severity of an osteoarthritis. We propose a narrative review of the literature dealing with various subjects about this challenging topic that is imaging, temporal evolution, etiology, differential diagnoses, and possible organization, together with a pictorial essay.

Strain distribution of the anterolateral ligament during internal rotation at different knee flexion angles: A biomechanical study on human cadavers

BACKGROUND

Injuries of the anterolateral ligament (ALL) are fairly common in patients with ruptures of the anterior cruciate ligament (ACL). Before considering repair or reconstruction of the ALL, the lack of knowledge with regard to the biomechanical behavior of this ligament must be considered. The purpose of this study was to analyze the strain of the ALL induced by tibial internal rotation at different flexion angles and find out the strain distribution features.

METHODS

The ALLs of ten fresh-frozen cadaver knees were dissected. All specimens underwent tibial internal rotation from 0° to 25° at 30°, 60°, 90°, and 120° of knee flexion. Strain distribution of the ALL during internal rotation was recorded by digital image correlation (DIC). The overall strain and sub-regional strain were measured.

RESULTS

The strain of the ALL increased with increasing tibial internal rotation. With 25° of internal rotation, the overall strain at each flexion angle was 12.89 ± 2.73% (30°), 15.32 ± 2.50% (60°), 18.94 ± 2.34% (90°), and 20.10 ± 3.27% (120°). The sub-regional strain was significantly different at all flexion angles. The strain of the distal 1/3 of the ALL was the greatest, followed by the middle 1/3, while the proximal 1/3 was the smallest (all P < 0.001).

CONCLUSION

The ALL resisted internal rotation of the tibia by becoming more tense with increasing rotation. A significantly high strain was observed in the distal portion near the tibial insertion site of the ALL, which may suggest that this region is prone to injury with excessive internal rotation.

Acute posterior cruciate ligament injuries: effect of location, severity, and associated injuries on surgical management

OBJECTIVE

To correlate MRI findings of patients with posterior cruciate ligament (PCL) injury and surgical management.

MATERIALS AND METHODS

A retrospective search yielded 79 acute PCL injuries (36 ± 16 years old, 21 F, 58 M). Two independent readers graded PCL tear location (proximal, middle, or distal third) and severity (low-grade or high-grade partial/complete) and evaluated injury of other knee structures. When available, operative reports were examined and the performed surgical procedure was compared with injury grade, location, and presence of associated injuries.

RESULTS

The most commonly injured knee structures in acute PCL tears were posterolateral corner (58/79, 73%) and anterior cruciate ligament (ACL) (48/79, 61%). Of the 64 patients with treatment information, 31/64 (48%) were managed surgically: 12/31 (39%) had PCL reconstruction, 13/31 (42%) had ACL reconstruction, 10/31 (32%) had posterolateral corner reconstruction, 9/31 (29%) had LCL reconstruction, 8/31 (26%) had meniscectomy, and 8/31 (26%) had fixation of a fracture. Proximal third PCL tear and multiligamentous injury were more commonly associated with surgical management (P < 0.05). Posterolateral and posteromedial corner, ACL, collateral ligament, meniscus, patellar retinaculum, and gastrocnemius muscle injury, and fracture were more likely to result in surgical management (P < 0.05). Patients with high-grade partial/complete PCL tear were more likely to have PCL reconstruction as a portion of surgical management (P < 0.05).

CONCLUSIONS

Location of PCL tear and presence of other knee injuries were associated with surgical management while high-grade/complete PCL tear grade was associated with PCL reconstruction. MRI reporting of PCL tear location, severity, and of other knee structure injuries is important for guiding clinical management.

Osteochondral Lesions of the Knee: Differentiating the Most Common Entities at MRI

Several pathologic conditions may manifest as an osteochondral lesion of the knee that consists of a localized abnormality involving subchondral marrow, subchondral bone, and articular cartilage. Although understanding of these conditions has evolved substantially with the use of high-spatial-resolution MRI and histologic correlation, it is impeded by inconsistent terminology and ambiguous abbreviations. Common entities include acute traumatic osteochondral injuries, subchondral insufficiency fracture, so-called spontaneous osteonecrosis of the knee, avascular necrosis, osteochondritis dissecans, and localized osteochondral abnormalities in osteoarthritis. Patient demographics, the clinical presentation, and the role of trauma are critical for differential diagnosis. A localized osteochondral defect can be created acutely or can develop as an end result of several chronic conditions. MRI features that aid in diagnosis include the location and extent of bone marrow edema, the presence of a fracture line, a hypointense area immediately subjacent to the subchondral bone plate, and deformity of the subchondral bone plate. These findings are essential in diagnosis of acute traumatic injuries, subchondral insufficiency fracture, and its potentially irreversible form, spontaneous osteonecrosis of the knee. If the lesion consists of a subchondral region demarcated from the surrounding bone, the demarcation should be examined for completeness and the presence of a "double-line sign" that is seen in avascular necrosis or findings of instability, which are important for proper evaluation of osteochondritis dissecans. Subchondral bone plate collapse, demonstrated by the presence of a depression or a fluid-filled cleft, can be seen in advanced stages of both avascular necrosis and subchondral insufficiency fracture, indicating irreversibility. Once the diagnosis is established, it is important to report pertinent MRI findings that may guide treatment of each condition. ^©RSNA, 2018 An earlier incorrect version of this article appeared online. This article was corrected on August 23, 2018.

Reliability assessment of a mechanism-based approach to post-injury knee magnetic resonance imaging interpretation by general radiologists

Background

A mechanism-based approach to post-injury knee magnetic resonance imaging (MRI) interpretation, following acute complex knee injury, is cited by several authors to provide increased reporting accuracy and efficiency, by allowing accurate prediction of injury to at-risk structures. This remains to our knowledge untested in a developing world setting and is of interest to us as South African general radiologists.

Objective

To assess the reliability of a mechanism-based approach to complex post-trauma knee MRI interpretation when implemented by general radiologists in a South African setting, and compare our results with the findings of North American authors who compiled and assessed the same classification. To measure the agreement between the observers.

Methods

A quantitative, observational, investigative, retrospective study was performed using a sample of 50 post-trauma knee MRI studies conducted at Grey's Hospital, Pietermaritzburg. Two investigators independently applied the consolidated mechanism-based approach compiled by Hayes et al. as a research tool to interpret the knee MRI studies, blinded to each other's findings.

Results

Injury mechanism was assigned in 32% of cases by the principle investigator and in 20% of cases by the supervisor, with fair agreement between the observers (k = 0.39). The investigators agreed that 62% of cases were not classifiable by mechanism, 26% because of highly complex injury and 26% because of non-specific findings.

Conclusion

Our findings indicate that the Hayes et al. classification is a non-ideal tool when used by general radiologists in our setting, as the pure injury mechanisms described in the classification were rare in our study group. Patient epidemiology and investigator experience are highlighted as potential limiting factors in this study. Despite this, we advocate that the concept of a mechanism-based approach for the interpretation of acute post-trauma knee MRI holds value for general radiologists, particularly in patients imaged before resolution of bone bruising (within 12-16 weeks of injury), and those injured in sporting and similar athletic activities.

Imaging of Athletic Injuries of Knee Ligaments and Menisci: Sports Imaging Series

Acute knee injuries are a common source of morbidity in athletes and if overlooked may result in chronic functional impairment. Magnetic resonance (MR) imaging of the knee has become the most commonly performed musculoskeletal MR examination and is an indispensable tool in the appropriate management of the injured athlete. Meniscal and ligamentous tearing are the most frequent indications for surgical intervention in sports injuries and an understanding of the anatomy, biomechanics, mechanisms of injury, and patterns of injury are all critical to accurate diagnosis and appropriate management. These will be discussed in reference to meniscal tears and injuries of the cruciate ligaments as well as injuries of the posterolateral and posteromedial corners of the knee. (©) RSNA, 2016.

Study of Imaging Pattern in Bone Marrow Oedema in MRI in Recent Knee Injuries and its Correlation with Type of Knee Injury

INTRODUCTION

The knee is a major weight bearing joint that provides mobility and stability during physical activity as well as balance while standing. If the knee is exposed to forces beyond its physiologic range, risk of injury to bone or soft tissue structures increases. A thorough understanding of knee injury patterns and their mechanisms may help in achieving more accurate assessment of injuries.

AIM

To identify imaging pattern in bone marrow oedema and to correlate the pattern of bone marrow oedema retrospectively with type of knee injury from clinical history.

MATERIALS AND METHODS

A cross-sectional study was done on all patients referred to Krishna Hospital, Karad for MRI knee with history of recent (< 6 weeks) knee injury. Study was conducted between May 2014 to September 2015 with a sample size of 200 patients. Plain radiograph of knee was done in all patients and they were scanned using 1.5 Tesla Seimens Avanto (Tim + Dot) with Tx/Rx 15 channel knee coil # Tim.

RESULTS

Among the 200 cases, bone marrow contusion was noted in 138 cases (69%) and absent contusion in 62 cases (31%). Bone marrow contusion showed five patterns (according to Sanders classification) i.e., Clip injury in 39 cases (28.3%), Pivot shift injury in 78 cases (56.5%), Dashboard injury in eight cases (5.8%), Hyperextension injury in four cases (2.9%), Lateral patellar dislocation in three cases (2.2%). In six cases (4.3%) no pattern of bone marrow contusion could be explained and was categorized as unclassified pattern.

CONCLUSION

Pivot shift pattern is most common contusion pattern and the most common type/mode of sports related injury. By analysing bone marrow contusion pattern, type/mode can be determined in most of the cases. By applying a biomechanical approach in MR interpretation, it is possible to detect lesions like ligament rupture and osseous contusion, to predict subtle but it might overlook important abnormalities.

A biomechanical approach to interpreting magnetic resonance imaging of knee injuries

This article discusses common injury mechanisms and the subsequent constellation of magnetic resonance (MR) imaging findings in the knee following trauma in the context of instability, as distinguished by the degree of knee flexion and tibial rotation at the time of initial injury, in addition to the direction and magnitude of the responsible force vectors. Using 3-dimensional imaging, common injury mechanisms are illustrated and correlated with MR imaging findings of the resulting osteochondral, ligamentous, meniscal, and musculotendinous lesions. The most common classification and grading systems for these individual lesions and their subsequent treatment implications are discussed.

Spectrum of injuries associated with paediatric ACL tears: an MRI pictorial review

OBJECTIVE

Magnetic resonance imaging (MRI) findings in anterior cruciate ligament (ACL) injury are well known, but most published reviews show obvious examples of associated injuries and give little focus to paediatric patients. Here, we demonstrate the spectrum of MRI appearances at common sites of associated injury in adolescents with ACL tears, emphasising age-specific issues.

METHODS

Pictorial review using images from children with surgically confirmed ACL tears after athletic injury.

RESULTS

ACL injury usually occurs with axial rotation in the valgus near full extension. The MRI findings can be obvious and important to management (ACL rupture), subtle but clinically important (lateral meniscus posterior attachment avulsion), obvious and unimportant to management (femoral condyle impaction injury), or subtle and possibly important (medial meniscocapsular junction tear). Paediatric-specific issues of note include tibial spine avulsion, normal difficulty visualising a thin ACL and posterolateral corner structures, and differentiation between incompletely closed physis and impaction fracture.

CONCLUSION

ACL tear is only the most obvious sign of a complex injury involving multiple structures. Awareness of the spectrum of secondary findings illustrated here and the features distinguishing them from normal variation can aid in accurate assessment of ACL tears and related injuries, enabling effective treatment planning and assessment of prognosis.

TEACHING POINTS

• The ACL in children normally appears thin or attenuated, while thickening and oedema suggest tear. • Displaced medial meniscal tears are significantly more common later post-injury than immediately. • The meniscofemoral ligaments merge with the posterior lateral meniscus, complicating tear assessment. • Tibial plateau impaction fractures can be difficult to distinguish from a partially closed physis. • Axial MR sequences are more sensitive/specific than coronal for diagnosis of medial collateral ligament (MCL) injury.

MR imaging of anterior knee pain: a pictorial essay

Anterior knee pathology is a frequent cause of joint pain and limitation of function and mobility among patients presenting to an orthopaedic department. Proper recognition and treatment of pathologic conditions depend on the knowledge of normal anatomy and of the various abnormalities, which affect this area of the knee and may present with anterior knee pain. A broad array of benign and malignant processes may be manifested as anterior knee discomfort, and this common clinical entity is among the most frequent indications for MR imaging of the lower extremities. Clinical history and physical examination are also of paramount importance. The disorders can be categorized and differentiated primarily according to their location. Traumatic or non-traumatic disorders of the patella, patellar retinacula, quadriceps and patellar tendons and supra or infrapatellar fat pad can be the source of symptoms. This article includes a comprehensive pictorial essay of the characteristic MR features of common and uncommon disorders causing anterior knee pain. For accurate assessment of the aforementioned clinical problem, a radiologist should be able to identify typical MR imaging patterns that contribute in establishing the correct diagnosis and thus tailoring the appropriate therapy. Level of evidence IV.

The trochlear cleft: the “black line” of the trochlear trough

OBJECTIVE

The “cartilage black line sign” is a recently described T2 dark cartilage lesion that we have identified appearing as a cleft in the trochlear trough. The purpose of our study was to define the MR imaging characteristics of a trochlear cleft, determine its incidence, and correlate the MR findings with arthroscopy.

MATERIALS AND METHODS

A total of 1,300 consecutive MR examinations of the knee were retrospectively reviewed by consensus of two fellowship-trained musculoskeletal radiologists. The MR imaging characteristics and location of a trochlear cleft were determined. Imaging results were compared to arthroscopy when available. Patient age and gender were compared to 25 randomly selected control patients without trochlear clefts.

RESULTS

A total of 25 (1.9%) individuals (11 females and 14 males; age range 19–45 years; mean age 28 years) were diagnosed with a trochlear cleft. The control group consisted of 11 females and 14 males; age range 19–83 years; mean age 46 years. Mean cleft length was 7 mm (range 6–12 mm); cleft location was consistently in the lower trochlear trough. No full-thickness cartilage defects were identified in the eight individuals in whom arthroscopic correlation was available. A grade 2 cartilage lesion was identified in a single individual; another progressed from grade 0 to a full-thickness trochlear lesion over an 8-month interval. Eight individuals were athletes. No significant difference in gender was noted between the two groups, however, the study group was significantly younger p<0.0001.

CONCLUSIONS

A trochlear cleft is a rare finding in young active individuals. It most likely indicates an incomplete cartilage fissure which may rarely progress to a full-thickness defect.