Acute Knee Pain- College Lacrosse Player


Christine S. Persaud, Mark Mirabelli, University of Rochester Medical Center, Rochester, NY.

Acknowledgments: Ilya Voloshin, John Goldblatt

email: ChristineSPersaud@gmail.com

HISTORY: 22 year old male lacrosse player with right knee pain and swelling x 2 days. Pain was described as diffuse with no associated erythema, fevers, chills, swelling in other joints, or mechanical symptoms. There was no inciting event. He had no limitation in his activities. He attempted to rest and elevate with no relief. On initial visit X-rays and MRI were ordered that were only remarkable for an effusion. On follow-up, an aspiration was done with 55mL of clear yellow joint fluid removed.


Vital Signs- normal

Gait- normal

Right knee - 1+ effusion, mild tenderness to palpation over the medial and lateral joint lines, pain with flexion, vague non focal pain with McMurrays ; neurovascularly intact.

DIFFERENITAL DIAGNOSIS: Meniscal Injury, Septic Arthritis, Rheumatologic Disease, Osteochondral injury

TESTS/RESULTS: Right Knee X-ray-moderate size joint effusion.

MRI right knee without contrast-ACL, PCL, MCL, LCL, distal quadriceps tendon, patellar tendon, patellar retinaculum intact, medial and lateral menisci intact; Small effusion.

Knee Aspiration#1: Aerobic culture- Staphylococcus epidermidis -broth only

Knee Aspiration#2: Aerobic culture Staphylococcus epidermidis - broth only

Culture from OR: Aerobic culture Staphylococcus epidermidis - broth only

CRP-9 RF5.3

FINAL DIAGNOSIS: Septic arthritis


The culture from the first aspirate showed Staphylococcus epidermidis from broth culture only and patient was advised to go to ER. In the ER a repeat aspiration was done showing Staphylococcus epidermidis from broth culture only. Although clinically the patient did not appear to have a septic knee, on follow-up he had persistent swelling with two positive cultures and was recommended for arthroscopic I&D. In the OR patient he had an arthrotomy with exploration, irrigation and drainage of copious green-tinged and straw-colored fluid. Cultures from the OR grew Staphylococcus epidermidis from broth only. Patient was seen by Infectious Disease, they felt the significance of the cultures were unclear because it only grew from the broth. Given that he had no other obvious cause for an effusion he was continued on Keflex for septic arthritis for 5 weeks. He was able to return to full activity and symptomatically improved.

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