Imaging the Athlete s Knee Peter Lowry, MD Musculoskeletal Radiology University of Colorado
None Disclosures
Knee Imaging: Radiographs Can be performed weight-bearing or non-weight-bearing View options AP Oblique Lateral (weight-bearing partially flexed vs x-table) Merchant/Sunrise Notch/Rosenberg view
AP view
Lateral
Sunrise View
Merchant View
Notch View
Rosenberg View
Knee Imaging: MRI Utilize proton density ( PD ) and fat-saturated proton density ( PD fat-sat ) sequences Modality of choice to evaluate ligaments, meniscus, and musculature surrounding knee
Knee Imaging: MRI Our protocol: Coronal PD and PDFS Sagittal PD and PDFS Axial PDFS Can we replace these with volumetric imaging?
Injuries of the athlete s knee Dislocation Transient patellar dislocation Ligament Injury ACL MCL Posterolateral corner Associated avulsions Meniscal Injury
Low velocity Nerve injury 20% Vascular injury 5% High velocity Higher rates of nerve and vascular injury Direction of tibia relative to femur Anterior Posterior Medial/Lateral Knee Dislocation
Anterior Dislocation 31% dislocations, hyperextension mechanism ACL and PCL usually torn MCL and LCL usually injured Vascular injury common, as popliteal artery is tethered at adductor hiatus and at soleus
Posterior Dislocation ACL and PCL usually injured Vascular injury can be more focal (transection) Peroneal nerve injury commonly accompanies vascular injury
Lateral knee dislocation Rare No vascular injury Peroneal nerve at risk Collateral and cruciate damage
Patellar Dislocation Usually transient Common knee dislocation Predisposing factors ELPS (excessive lateral pressure syndrome)-many causes Shallow trochlear groove Patella alta Distinctive pattern Please look for these in patients with effusion Look through the femur
Patellar Dislocation Usually transient Most common knee dislocation Predisposing factors ELPS (excessive lateral pressure syndrome)-many causes Shallow trochlear groove Patella alta Findings Kissing contusion pattern Edema/tearing of MPFL
Ligament Injury Radiographs Effusion Radiographic drawer sign Avulsions ACL PCL Segond/Reverse Segond Arcuate MCL Deep femoral sulcus sign
Ligament Injuries ACL Pivot-shift mechanism Radiographic drawer sign Segond fracture Deep femoral sulcus sign Tibial spine avulsion
Segond Fracture Avulsion fracture of the lateral aspect of the proximal tibia at the insertion of the lateral capsular ligament Injury associations ACL tear(75-100%) Meniscal injury (66-70%)
Arcuate sign of fibular head avulsion Avulsion of fibular tip can either be due to conjoined tendon avulsion (more anterolateral) or avulsion of posterolateral ligamentous insertions (more posterior) Necessitates MRI PLC injury requires early treatment to approximate tissues before significant scarring PLC is associated with ACL and/or PCL tears in approx 90% ACL repair with unrecognized PLC injury will fail
Deep sulcus sign/kissing contusions
Tibial spine avulsion Insertion site of ACL Seen almost exclusively in children Usually associated with lipohemarthrosis
Ligament Injuries PCL Much less common in athletics than ACL/MCL Radiographic posterior drawer sign Reverse Segond or tibial spine avulsion
Can be subtle PCL Avulsion
Ligament Injuries MCL Valgus stress or twisting mechanism Medial pain Pellegrini-Stieda avulsion Deep femoral sulcus sign
MCL Avulsion Can avulse from femoral or tibial attachment Tibial attachment is 6cm distal to the joint line Distal tear is a surgical lesion
Posterolateral Corner Components: Fibular collateral ligament Biceps/conjoint tendon Popliteus Arcuate ligamentous complex Popliteofibular ligament Assessed on PDFS MRI
Meniscal Injury Types: Radial Free Edge Horizontal cleavage Vertical longitudinal Bucket handle
Meniscal Injury Vertical Long
Meniscal Injury - Radial
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