A Diagnosis of Exclusion

[iwhitney]

For this patient encounter reflection, I wanted to discuss a recent patient evaluation that challenged my ability to effectively rule out differential diagnoses and come to a conclusive diagnosis. The patient is a 50 y.o. female who presented with a referral for anterior L knee pain and medial thigh pain that began in July 2022 (I saw her in January 2023). Her pain began insidiously with no apparent cause or mechanism of injury other than resuming an exercise routine after being sick for a few weeks. The pain was initially quite intense and most severe at night, where it was unrelenting and did not go away if she changed position. This was obviously a red flag, so I wanted to make sure I dove deeper into the care she’s received and what’s been done to rule out any non-MSK involvement in her presentation. She had been seen by two of the sports medicine/orthopaedic doctors at UVA, who decided to perform imaging (MRI) because of these symptoms and her family history of breast cancer. The MRI was negative for any significant trauma or mass, although it did show a benign enchondroma at the medial femoral condyle, along with glute medius tendinopathy. Despite this imaging, I asked further red flag questions to be confident I didn’t need to refer the patient elsewhere. She denied any history of cancer, sudden weight gain/loss (5-10% BW over past 3-6 months), and she currently wasn’t experiencing any night pain. In early December, the patient was given a corticosteroid injection into her knee and was prescribed gabapentin and since has had very little to no pain. Her referring provider has scheduled her for an EMG study to determine any neural involvement since it is not entirely clear whether the injection or gabapentin helped.
Objective asterisks from my evaluation are as follows: full, pain-free knee/hip ROM, dynamic valgus during step down test, increased weakness/sway during SL balance on L, (-) McMurray’s/Thessaly’s, (-) knee ligamentous stability tests, (+) patellar compression, (+) patellar grind, weakness into hip abduction and knee extension, and pain reproduction with palpation superior, lateral to patella. It was pretty obvious at this point that her pain was likely coming from the patellofemoral joint, especially due to some of the muscle performance and movement coordination deficits I observed through strength and functional testing. Reflecting back on this patient and after our discussion on PFPS at the OMPTS this past weekend, I realize my examination could’ve definitely been more thorough, but also better at ensuring I ruled out differentials. For starters, I didn’t rule out any nerve involvement, which should’ve been on my radar given the patient was prescribed gabapentin and is currently scheduled for an EMG study. I also think I could’ve done a better job at evaluating both above and below the knee due to the multifactorial nature of PFPS and potential contributions from poor mechanics at the hip and ankle. I could’ve looked at more functional tests to observe movement coordination and I didn’t look at the ankle at all during my examination, which obviously could be an important asterisk early on if short term orthotics are deemed necessary.
Overall, I feel that our discussion this past course series weekend on PFPS made me realize I have some room for improvement in my evaluation of patients presenting with anterior knee pain. I have seen a good amount of patients with PFPS, so hopefully this reflection will shine some light on how I could improve my evaluation and treatment for this population. Some other aspects of this population that we discussed from this weekend that I plan to look more into with this patient include the biopsychosocial nature of PFPS and the potential for altered central pain processing. It’s definitely more clear to me that this needs to be a diagnosis of exclusion, not just from the standpoint of ruling out differentials, but also due to the potential influence of so many factors that could be contributing to the patient’s pain. I would love to hear about anyone else’s success with PFPS or how you approach your evaluations for this population. I also feel this brings up a good conversation topic on the need for an actual diagnosis in physical therapy. How do you approach patients that are adamant about receiving an actual diagnosis, especially if they are presenting without any biomedical contributions to their pain?

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