?ACL involvement

I work alone and need some advice please. i have a young lad who was doing a arduous course which involved walk/running for 8 miles while carrying weight. During the first mile he placed his foot which went medially and his body slipped laterally across his knee. He heard/felt a 'pop'. He was able to continue on for the other 7 miles with pain, but no giving way or locking. He then checked his knee and had some swelling. He continued on the course for another 3 days until the staff noticed he was limping. He was sent to see a physio, who checked for ACL which was -ve: gave a knee barce and took him off the course.

I now have him 10 days post off course (14 days post injury), He is wearing a brace as his knee feels unstable, but it has not given way/locked. Lachmans, Ant Drawer, Pivot shift are all negative. All Collat ligt and mensiscus tests are -ve. He did have some some PF jt swelling/crepitus which was sorted out by use of PEME. He was sore lateral and superior border of patella. He now just has soreness superior border of the patella, but still the feeling of instability. I am unable to get a scan for 28 days.
He is a very fit lad and wishes to attempt this course in 6 months time.

I am wondering if i have missed something ACL-wise; or if he could have disclocated his patella which spontaneously went back; or disrupted fibres of the capsule; torn quad fibres.

Does anyone have any ideas

Hey there,

To me it sounds like he's partially subluxed his patella if he is tender on the border of the patella and probably bruised or done damage to the cartilage in the patella. The pain has inhibited the muscle activity around the knee hence a feeling of instability with weightbearing.

I would do a scan anyways to hopefully clear the knee of ACL rupture. Sometimes I have felt a normal ACL on testing but scans have shown it has completely torn! Sometimes the hamstring is still active at rest and can affect the testing.

in the meantime, treat him conservatively in the meantime with your general knee strengthening stuff and work alot on his VMO/quads/core stability (as pain permits) and progress as required. Should probably take 6-8 weeks of rehab for his knee.

Hope this helps. all the best with the patient.

Agreed. sounds more like PFJ subluzation with spontaneous relocation. regaining quads strength should help with the sensation of instability and a scan is nice if it's easily accessible to see what else might be happening in the joint but retesting PCL/ACL when things settle further should be sufficient if the stability and strength restores well with exercises. loads of proprioception exercises and ankle strength for tib and and peroneals also should help.

cheers
msk101 :)