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

Jaremko JL, Guenther ZD, Jans LB, Macmahon PJ - Insights Imaging (2013)

Bottom Line: ACL injury usually occurs with axial rotation in the valgus near full extension.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.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. • 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology and Diagnostic Imaging, 2A2.42 Walter Mackenzie Health Sciences Centre, University of Alberta, Edmonton, Alberta, Canada, T6G 2B7, jjaremko@ualberta.ca.

ABSTRACT

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.

No MeSH data available.


Related in: MedlinePlus

Medial collateral ligament on coronal PD images, reoriented as if all were left knees for comparative purposes. a Normal MCL, appearing slightly thicker proximally (arrow) than distally, which is typical. Also note the intact ACL (arrowhead). b A low-grade partial tear of deep MCL fibres including medial meniscofemoral ligament (arrow). Superficial fibres are intact (arrowhead). c High-grade sprain involving nearly the entire length of MCL; note normal appearing tibial attachment (arrow). d MCL rupture just distal to knee joint line (arrow). e A distal rupture near tibial attachment (arrow), with associated tears of deep fibres including meniscofemoral and meniscotibial ligaments (arrowheads)
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Fig9: Medial collateral ligament on coronal PD images, reoriented as if all were left knees for comparative purposes. a Normal MCL, appearing slightly thicker proximally (arrow) than distally, which is typical. Also note the intact ACL (arrowhead). b A low-grade partial tear of deep MCL fibres including medial meniscofemoral ligament (arrow). Superficial fibres are intact (arrowhead). c High-grade sprain involving nearly the entire length of MCL; note normal appearing tibial attachment (arrow). d MCL rupture just distal to knee joint line (arrow). e A distal rupture near tibial attachment (arrow), with associated tears of deep fibres including meniscofemoral and meniscotibial ligaments (arrowheads)

Mentions: Valgus positioning in most ACL injuries results in tensile stress on the medial collateral ligament, which can lead to an MCL tear (Fig. 9). For MR diagnosis, in our experience the axial sequence is more sensitive and specific than coronal sequences, where apparent ligament thickening is often due to volume averaging. The coronal plane is useful to determine location and extent of tear once diagnosed in the axial plane. The MCL was sprained (low or high grade) in 22 % of patients in a paediatric series [3]. In the last 110 cases of ACL tears at our institution, there were seven high grade MCL tears, four proximal at femoral attachment, one at midsubstance and two distal avulsions at tibial attachment. Although our numbers are small, this distribution differs from an adult series in which combined ACL and MCL ruptures more often completely tore the MCL tibial attachment (53 %) than the femoral attachment (26 %) [31]. The variation might be spurious, or due to differences in relative tension of ACL, MCL and joint capsule compared with adults. The MCL is a complex structure with two main layers visible at MRI, the superficial tibiofemoral layer and deep meniscofemoral and meniscotibial fibres firmly adherent to the medial meniscus [32]. Isolated tears of deep MCL fibres are diagnosed when the main superficial fibres are intact but no low-signal struts are visible joining the MCL to the medial meniscus. These tears can occur with ACL injury (Fig. 9b) and can also extend into the attached medial meniscus. Most MCL tears, whether involving deep and/or superficial fibres, are treated non-operatively, but it is important to recognise the location of injury within the MCL because proximal tears may adhere to the capsule and limit motion, requiring aggressive physiotherapy, while distal avulsions may require surgical intervention since the pes anserinus tendons can become entrapped between ligament and bone [33].Fig. 9


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

Jaremko JL, Guenther ZD, Jans LB, Macmahon PJ - Insights Imaging (2013)

Medial collateral ligament on coronal PD images, reoriented as if all were left knees for comparative purposes. a Normal MCL, appearing slightly thicker proximally (arrow) than distally, which is typical. Also note the intact ACL (arrowhead). b A low-grade partial tear of deep MCL fibres including medial meniscofemoral ligament (arrow). Superficial fibres are intact (arrowhead). c High-grade sprain involving nearly the entire length of MCL; note normal appearing tibial attachment (arrow). d MCL rupture just distal to knee joint line (arrow). e A distal rupture near tibial attachment (arrow), with associated tears of deep fibres including meniscofemoral and meniscotibial ligaments (arrowheads)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Fig9: Medial collateral ligament on coronal PD images, reoriented as if all were left knees for comparative purposes. a Normal MCL, appearing slightly thicker proximally (arrow) than distally, which is typical. Also note the intact ACL (arrowhead). b A low-grade partial tear of deep MCL fibres including medial meniscofemoral ligament (arrow). Superficial fibres are intact (arrowhead). c High-grade sprain involving nearly the entire length of MCL; note normal appearing tibial attachment (arrow). d MCL rupture just distal to knee joint line (arrow). e A distal rupture near tibial attachment (arrow), with associated tears of deep fibres including meniscofemoral and meniscotibial ligaments (arrowheads)
Mentions: Valgus positioning in most ACL injuries results in tensile stress on the medial collateral ligament, which can lead to an MCL tear (Fig. 9). For MR diagnosis, in our experience the axial sequence is more sensitive and specific than coronal sequences, where apparent ligament thickening is often due to volume averaging. The coronal plane is useful to determine location and extent of tear once diagnosed in the axial plane. The MCL was sprained (low or high grade) in 22 % of patients in a paediatric series [3]. In the last 110 cases of ACL tears at our institution, there were seven high grade MCL tears, four proximal at femoral attachment, one at midsubstance and two distal avulsions at tibial attachment. Although our numbers are small, this distribution differs from an adult series in which combined ACL and MCL ruptures more often completely tore the MCL tibial attachment (53 %) than the femoral attachment (26 %) [31]. The variation might be spurious, or due to differences in relative tension of ACL, MCL and joint capsule compared with adults. The MCL is a complex structure with two main layers visible at MRI, the superficial tibiofemoral layer and deep meniscofemoral and meniscotibial fibres firmly adherent to the medial meniscus [32]. Isolated tears of deep MCL fibres are diagnosed when the main superficial fibres are intact but no low-signal struts are visible joining the MCL to the medial meniscus. These tears can occur with ACL injury (Fig. 9b) and can also extend into the attached medial meniscus. Most MCL tears, whether involving deep and/or superficial fibres, are treated non-operatively, but it is important to recognise the location of injury within the MCL because proximal tears may adhere to the capsule and limit motion, requiring aggressive physiotherapy, while distal avulsions may require surgical intervention since the pes anserinus tendons can become entrapped between ligament and bone [33].Fig. 9

Bottom Line: ACL injury usually occurs with axial rotation in the valgus near full extension.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.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. • 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology and Diagnostic Imaging, 2A2.42 Walter Mackenzie Health Sciences Centre, University of Alberta, Edmonton, Alberta, Canada, T6G 2B7, jjaremko@ualberta.ca.

ABSTRACT

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.

No MeSH data available.


Related in: MedlinePlus