The Curious Case Of The Non-swollen Knee - Page #4
 

Working Diagnosis:
ACL tear with small lateral meniscus tear and bone contusion

Treatment:
ACL reconstruction with small lateral meniscectomy

Outcome:
Return to sport depends on recovery and rehabilitation. Studies have shown that without appropriate rehabilitation and return to full strength and range of motion that the chance of re-injury is significantly higher. There is also increased risk of injury to the contralateral ACL. Not only that but the risk of injury of other joints including the ankle increases as well after ACL reconstruction. The athlete described here has been progressing through his rehabilitation very nicely. He had full ROM at his follow up visits and was regaining his strength. His goal is to be ready for the start of the upcoming season.

Author's Comments:
The ACL receives it blood supply from a branch of the middle genicular artery and an anastomosis of the inferior medial genicular artery and inferior lateral genicular artery. The former supplies the proximal portion of the ACL and the latter provides blood supply to the distal portion of the ACL. In comparison, the middle portion of the ACL is less vascular than the proximal and distal portions. This brings up the question of 'if someone tears their ACL in the middle aspect, will they not swell as much or at all?' Based on expert opinion, the likelihood of an ACL tear with little to no effusion on exam is probably less than 10%. It does occur, but not very often. Of the times that it occurs different hypotheses arise as to how: prior partial tear that is now completely torn, prior complete tear that was stabilized by surrounding musculature, or tear through the relatively avascular component of the ACL with minimal disruption of the surrounding vasculature. Little information on incidence or prevalence of ACL tears with no effusion can be discovered in the literature. Discussions with orthopedic surgeons has shown that ACL tears do occur with minimal to no effusion present on exam, but the exact mechanism is not completely understood although different feasible hypotheses exist. If the exam and history are concerning for ACL tear, but there is little swelling associated with the injury, consider obtaining additional imaging and further work up. ACL tears can occur without a large joint effusion on exam.

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