Knee – ACL graft

CASE HISTORY

Pain incisional abscess.

TECHNICAL FACTORS

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

KEY IMAGES

This case has no key images.

CASE FINDINGS

• No evidence of patellofemoral chondromalacia. Small effusion. The physes are open. MCL and LCL complexes are intact. The PCL is intact. Peri- and retrocruciate capsulitis. 
• ACL graft again present. Mild swelling of the graft present without tear. However mild anterior tibial translation present suggesting functional insufficiency and graft impingement. There is now evidence of an approximately 13 x 9 x 12mm arthrofibrosis or cyclops lesion anterior to the tibial eminences. 
• There is widening of the osseous tunnel surrounding the tibial interference screw consistent with tunnel synovitis. Small fracture of the distal segment of the tibial interference screw also present. Dehiscence of the nearby anteromedial aspect of the proximal tibial metaphysis present which is contiguous with a small 1 x 0.7 x 0.9cm subcutaneous fluid collection suggestive of a small subcutaneous abscess smaller compared to the prior exam. However there is widening of the tibial tunnel surrounding the interference screw (crossing the physis) with large surrounding area of high-grade marrow edema concerning for infection or abscess of the tibial interference screw tunnel and also highly suggestive for surrounding osteomyelitis. Surrounding soft tissue swelling. 
• Medial and lateral menisci are intact without evidence of tear. No evidence of medial or lateral compartment chondromalacia.
• Open growth plates.

CASE CONCLUSION

• Intact ACL graft but within the suggestion of mild functional insufficiency and impingement. New small cyclops lesion. 
• Mildly increased tibial tunnel synovitis with mild widening of the osseous tunnel. Surrounding high-grade marrow edema highly suggestive of early or evolving osteomyelitis. Fracture of the distal segment of the distal tibial interference screw. 
• Dehiscence of the anteromedial aspect of the proximal tibial metaphysis contiguous with the tunnel synovitis with adjacent small fluid collection or possible abscess. This subcutaneous abscess has decreased in size compared to the prior exam. 
• Open growth plates.