Orthopedic Surgery

PCP submission

39 yo F presents to clinic to discuss R knee popping out x 1 year and pain during this but otherwise no pain or swelling with movements. will be sitting on the couch weird and has to pop it back into place in order to walk; had skiing accident years ago and never had imaging afterwards; declines PT.
EXAM: normal knee exam, no laxity.
Differential: Possible patella dislocation, ordered knee xray 3 views
R KNEE XRAY:
Findings: No fractures or dislocations. Articular surfaces are intact. No joint effusions. Bone mineralization and soft tissues are unremarkable.
Impression: No acute bony pathology.

1. What is your likely diagnosis based on this description? Could it be patella subluxation? What about if she feels like the whole joint is popping out of place?
2. What would you recommend for this, especially since it only occurs intermittently and then resolves when she pops it back into place?

Specialist response

Thank you for this consult. Based on the history, this does sound like episodes of patellar subluxation (which is relatively common in females of this age group). The first lines of treatment include physical therapy to work on quad strengthening, a patellar stabilization brace (can get online such as Amazon), avoidance of offending activities (squatting, crouching, kneeling), rest, ice, and NSAIDs. Many cases of patellar subluxation are related to the patient’s underlying anatomy and can improve with conservative treatment. Given her history of injury, it is possible that the patient injured her medial patellofemoral ligament (MPFL) which may make the problem less likely to resolve with non-surgical methods. If she does not respond to 6-8 weeks of the above measures, it is reasonable to consider MRI to evaluate for MPFL injury and/or patellar chondromalacia (early kneecap arthritis). The episodes of subluxation are not necessarily dangerous but could risk damaging the kneecap cartilage if they are recurrent. Hope this helps.