36-year-old female with knee locking after kickball game

Case
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36-year-old female injured knee playing kick ball one week ago knee has locked and unable to straighten. Prior ACL repair. Assess for MMT ACL retear internal derangement.

Long- and short-axis fat- and water-weighted images were performed. 

  • Susceptibility distortion distal femoral diaphysis associated with prior ACL autograft. 
  • Diffuse swelling about the autograft. Evidence of discontinuity of the anterior aspect of the autograft at the proximal tibial tunnel. The posterior aspect of the graft appears intact. Overall high grade tear of the graft. No passive anterior tibial translation. Correlate with physical exam to determine functional stability. 
  • Intact PCL despite adjacent swelling. 
  • Intact MCL which also shows mild swelling which may represent low grade MCL sprain. 
  • Intact LCL complex posterolateral stabilizers and iliotibial band. 
  • Intact extensor mechanism. Surgical changes of the patellar tendon from autograft surgery. 
  • No bone contusion microtrabecular or macrofracture. No intraarticular bodies. 
  • Diminutive medial meniscus and contour deformity of the meniscus. Anteromedially displaced 3cm bucket-handle tear. Undersurface partial thickness tear posterior horn.
  • Prominent medial joint line swelling. 
  • Small suprapatellar proteinaceous effusion. 
  • Postsurgical chronic patellar fibrosis and Hoffa fat pad fibrosis associated with prior ACL surgery. 
  • Intact lateral meniscus. 
  • Mild squaring of the medial femorotibial compartment narrowed joint space mild thinning of the weightbearing articular cartilage in keeping with posttraumatic moderate severity chondromalacia and mild arthrosis. No advanced lateral compartment or patellofemoral arthrosis or erosive chondromalacia. 
  • S/P ACL autograft repair and evidence of high grade retear of the graft. Clinical evaluation of femorotibial stability will determine functional integrity of the remaining ACL graft. 
  • Low grade MCL sprain. Remaining ligaments intact. 
  • Diminutive medial meniscus and contour deformity of the meniscus with anteromedially displaced 3cm bucket handle meniscal tear.  Undersurface partial thickness tear posterior horn.  Medial joint line capsulitis. 
  • Small proteinaceous suprapatellar and intercondylar notch effusion. 
  • No acute osseous injury.  
  • Posttraumatic moderate severity medial compartment chondromalacia and mild arthrosis.