Working Diagnosis:
Calcium pyrophosphate dihydrate
crystal deposition (CPPD) complicating
complex meniscal tears and advanced
chondromalacia in a knee joint with
previous ACL reconstruction.

Treatment:
Initial treatment included aspiration of 140 mL of clear synovial fluid with normal string sign, subsequent
corticosteroid injection, knee compression, naproxen and relative rest. Upon recurrent swelling, a second aspiration resulted in 140 mL of clear synovial fluid which was sent for analysis.

Following positive CPPD analysis, treatment was initiated with colchicine following consultation with Rheumatology. Following a discussion with the athlete and orthopedic surgeon, an arthroscopy of the knee was completed including partial medial and lateral meniscectomy, abrasion arthroplasty, removal of chondral loose bodies, and chondroplasty of the patella.

Outcome:
The patient completed rehabilitation and was able to participate in the later stages of the college basketball season.
He appeared in multiple games during the season with no significant issue or subsequent injury. Recurrent swelling was successfully treated with naproxen.

Author's Comments:
CPPD disease (including pseudogout) is a common cause of joint arthropathy, but it is far more common in older populations. CPPD can be related to systemic diseases such as hyperparathyroidism or hemochromatosis but is often idiopathic. There is an increased risk of CPPD in patients with history of knee surgeries, namely meniscectomy.
This case demonstrates the importance of completing a thorough workup for young athletes with a knee effusion. While CPPD and other less common maladies may be a smaller contributor to pain and effusion, it is important to have all information available to assist with medical decision-making and return to play.

Editor's Comments:
While traumatic injury is the main cause of joint pain and swelling in a young athlete, we must not forget to maintain a broad differential including other less common pathologies such as CPPD disease or auto-inflammatory arthritis. Joint aspiration and synovial fluid analysis is helpful to identify the presence of crystals or other findings to help make the diagnosis. Treatment options for acute CPPD disease include intra-articular glucocorticoid injection, oral anti-inflammatory medications such as naproxen, and oral colchicine.

References:
Rosenthal AK, Ryan LM. Calcium Pyrophosphate Deposition Disease. N Engl J Med. 2016 Jun 30;374(26):2575-84. doi: 10.1056/NEJMra1511117. PMID: 27355536; PMCID: PMC6240444.

Hammoudeh M, Siam AR. Pseudogout in a young patient. Clin Rheumatol. 1998;17(3):242-5. doi: 10.1007/BF01451057. PMID: 9694062.

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