Imaging the Athlete s Knee. Peter Lowry, MD Musculoskeletal Radiology University of Colorado

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1 Imaging the Athlete s Knee Peter Lowry, MD Musculoskeletal Radiology University of Colorado

2 None Disclosures

3 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

4 AP view

5 Lateral

6 Sunrise View

7 Merchant View

8 Notch View

9 Rosenberg View

10 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

11 Knee Imaging: MRI Our protocol: Coronal PD and PDFS Sagittal PD and PDFS Axial PDFS Can we replace these with volumetric imaging?

12 Injuries of the athlete s knee Dislocation Transient patellar dislocation Ligament Injury ACL MCL Posterolateral corner Associated avulsions Meniscal Injury

13 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

14 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

15 Posterior Dislocation ACL and PCL usually injured Vascular injury can be more focal (transection) Peroneal nerve injury commonly accompanies vascular injury

16 Lateral knee dislocation Rare No vascular injury Peroneal nerve at risk Collateral and cruciate damage

17 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

18 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

19 Ligament Injury Radiographs Effusion Radiographic drawer sign Avulsions ACL PCL Segond/Reverse Segond Arcuate MCL Deep femoral sulcus sign

20 Ligament Injuries ACL Pivot-shift mechanism Radiographic drawer sign Segond fracture Deep femoral sulcus sign Tibial spine avulsion

21 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%)

22 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

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26 Deep sulcus sign/kissing contusions

27 Tibial spine avulsion Insertion site of ACL Seen almost exclusively in children Usually associated with lipohemarthrosis

28 Ligament Injuries PCL Much less common in athletics than ACL/MCL Radiographic posterior drawer sign Reverse Segond or tibial spine avulsion

29 Can be subtle PCL Avulsion

30 Ligament Injuries MCL Valgus stress or twisting mechanism Medial pain Pellegrini-Stieda avulsion Deep femoral sulcus sign

31 MCL Avulsion Can avulse from femoral or tibial attachment Tibial attachment is 6cm distal to the joint line Distal tear is a surgical lesion

32 Posterolateral Corner Components: Fibular collateral ligament Biceps/conjoint tendon Popliteus Arcuate ligamentous complex Popliteofibular ligament Assessed on PDFS MRI

33 Meniscal Injury Types: Radial Free Edge Horizontal cleavage Vertical longitudinal Bucket handle

34 Meniscal Injury Vertical Long

35 Meniscal Injury - Radial

36 Thank you!