What is the cause of a lump on the medial aspect of the left knee, present for 3 weeks, with associated paresthesia and radiation of symptoms down the front of the knee, worsened by activity and at night, in a patient who experienced a twisting injury 2 months prior and has been taking Ibuprofen (ibuprofen) and Tylenol (acetaminophen)?

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From the Guidelines

The patient's presentation of a lump on the medial aspect of her left knee with associated pins and needles sensation and radiation of pain down the front of her knee, especially worsening at night and with physical activity, suggests a possible meniscal injury or other soft tissue pathology, and thus, a referral for physical therapy and consideration of pharmacotherapy such as topical NSAIDs or duloxetine should be prioritized. The patient's history of twisting her knee 2 months ago, which caused significant pain, supports the possibility of an underlying musculoskeletal issue that has not fully resolved. Given her current symptoms and the fact that she has been self-treating with ibuprofen and acetaminophen, it is essential to reassess her treatment plan. According to the 2020 VA/DoD Clinical Practice Guideline for the Non-Surgical Management of Hip & Knee Osteoarthritis 1, consideration should be given to early referral for physical therapy based on pain severity, functional limitations, and adherence.

The guideline also suggests offering acetaminophen and/or oral NSAIDs for pain associated with OA of the hip and knee, with duloxetine being an option for patients with moderate-to-severe OA pain 1. It is crucial to educate the patient on the proper use of duloxetine, including taking it daily and tapering it over at least 2 to 4 weeks when discontinuing 1. The patient's request for laboratory tests should be evaluated in the context of her clinical presentation, but the primary focus should be on addressing her symptoms and improving her quality of life through appropriate management of her potential meniscal injury or other soft tissue pathology.

Key points to consider in the patient's management include:

  • Referral for physical therapy to address pain severity and functional limitations
  • Consideration of pharmacotherapy such as topical NSAIDs or duloxetine for pain management
  • Education on the proper use of duloxetine and potential side effects
  • Evaluation of the need for laboratory tests based on the patient's clinical presentation
  • Focus on improving the patient's quality of life through appropriate management of her symptoms.

From the Research

History of Present Illness (HPI)

The patient reports a lump in the medial area of her left knee for 3 weeks. The onset of the lump was 3 weeks ago, and it is characterized by a pins and needles sensation. The patient experiences radiation of the sensation down the front of her knee. She denies any associated symptoms. The timing of the sensation is worse at night and when walking at work. The patient reports that activity exacerbates the sensation, with a pain scale of 3/10 to 6/10.

Relevant Medical History

The patient reports twisting her knee 2 months ago, which caused her enough pain to sit down. She has been taking ibuprofen and Tylenol for pain management. The patient also requests labs to be done.

Possible Diagnostic Approaches

  • The patient's symptoms could be related to a soft-tissue lump or bump, and a systematic approach to evaluation, diagnosis, and management may be necessary 2.
  • Laboratory tests such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) may be used to aid in diagnosis, but it is essential to understand the physiologic principles behind these tests and their limitations 3, 4, 5.
  • The patient's use of ibuprofen and Tylenol may affect the results of ESR and CRP tests, as statin or nonsteroidal anti-inflammatory drug use has been associated with lower ESR in patients with certain conditions 6.

Key Points to Consider

  • The patient's symptoms and medical history will guide the diagnostic approach and laboratory tests.
  • A thorough understanding of the patient's condition and the limitations of laboratory tests is necessary for proper diagnosis and management.
  • The patient's request for labs will be considered in the context of her symptoms and medical history.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Evaluating Soft-Tissue Lumps and Bumps.

Missouri medicine, 2017

Research

Erythrocyte Sedimentation Rate and C-reactive Protein Measurements and Their Relevance in Clinical Medicine.

WMJ : official publication of the State Medical Society of Wisconsin, 2016

Research

Statin or nonsteroidal anti-inflammatory drug use is associated with lower erythrocyte sedimentation rate in patients with giant cell arteritis.

Journal of neuro-ophthalmology : the official journal of the North American Neuro-Ophthalmology Society, 2011

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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