SUBACUTE KNEE PAIN IS NOT ALWAYS WHAT IT SEEMS Steven R. Sabo, MD Sports Medicine Fellow 2011-2012 University of South Florida and Morton Plant Mease.
Post on 28-Mar-2015
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SUBACUTE KNEE PAIN IS NOT ALWAYS WHAT IT SEEMS
Steven R. Sabo, MDSports Medicine Fellow 2011-2012University of South Florida and
Morton Plant Mease / BayCare Health System
History of Present Illness
• 36 y.o. male softball player and auto mechanic c/o right knee pain, stiffness, and swelling x 3 months
• Twisted right knee walking down stairs.
• Posterior knee joint 6/10 pain, increases with any knee flexion.
• No giving way, locking, or prior Hx of trauma.
R knee Injury x 3 months
• MHX/SHX: Prior left knee sprain 1 yr ago resolved. No chronic injuries or diseases.
• Meds: None Allergies: Pen causes rash.• Exam: 6/10 Pain @ deep popliteal fossa,Moderate size joint effusion without warmthNo joint line tendernessROM decreased (only 10 to 130 degrees)Equivocal Thessaly testNo ligament defect noted on stress tests
Differential Diagnosis:
• Meniscal tear with effusion
• Baker’s cyst
• partial ACL/PCL ligament injury with effusion
• Osteoarthritis, loose body, Stress fracture.
• infectious arthritis, gout or pseudogout
• RA autoimmune arthritis, psoriatic or seronegative arthritis, amyloidosis, SLE
Imaging and Special Studies:
• X-rays revealed mild osteoarthritis• CBC, ESR, CRP, RF and ANA ordered by PCM
and were normal• Aspiration of knee = 10 ml of blood tinged “rusty”
colored synovial fluid without evidence of crystals, infection, or malignant cells.
• Stiffness and effusion recurred rapidly before the next day
• Sports Med / Ortho ordered an MRI.
MRI of Right Knee
• Diffuse non-calcified nodular synovial thickening
• 8.5 cm diameter Baker’s popliteal cyst
• Chondromalacia Patella, mild diffuse
• No ligament derangement, meniscal tear, fracture, or bone contusion.
New Differential Diagnosis:
• Synovial Chondromatosis
• Chronic Hemarthrosis
• Rheumatoid Arthritis
• Pigmented Villonodular Synovitis
• Benign fibroblastic tumors
Surgery and Pathology Results:• Exploratory open arthrotomy with synovectomy
done because of MRI findings.• Dark Red 16 x 12 x 6 cm large lobulated mass
immediately extruded from the surgical wound as if under pressure.
• Multiple lesions had eroded partially into the undersurface and margins of the patella.
• Pathology: hypervascular proliferative synovium containing multinucleated giant cells, macrophages, and hemosiderin.
Normal Synovium vs.Pigmented Villonodular Synovitis
• Normal PVNS
Final Diagnosis:Pigmented Villonodular Synovitis
(PVNS)• Treatment: Synovectomy for complete
removal of lesion, post-op hinged knee brace, then physical therapy.
• Outcome: Patient had return of normal joint function. Normal ROM and strength. No recurrence of pain or effusion @ 6 months
• PX: Diffuse PVNS recurs up to 46%, Localized PVNS recurs at 8%
Tx options for recurrence
• Repeat Synovectomy• XRT Radiation Therapy 4000 cGy• If enough of joint is destroyed: bone grafting or
total joint replacement• Tumor Necrosis Factor α inhibitor (class of drugs):
off label use to decrease inflammatory response for refractory PVNS, reported in Rheumatology case studies. Examples: etanercept (Enbrel), infliximab (Remicade), adalimumab (Humira).
Take Home Messages:
• Relatively rare (incidence 1.8 cases/ million people), usually benign intra-articular and peri-articular hyperproliferation of synoviumCause debated: malignant transformation vs. chronic inflammatory
• Removal of the lesion is usually curative• Repeat imaging is prudent since it recurs• Important to occasionally widen your DDX for
knee pain.
Special Thanks:Our patient (written consent given to allow this case report)
Allen Hughes, MDOrthopedic Specialties of Clearwater FL
Sean Bryan, MD
USF / MPM Sports Medicine Fellowship andFamily Medicine Residency Program Director
Ted Farrar, MDUSF / MPM Sports Medicine Fellowship Associate Director
Jonathan Squires, MDRadiology Associates of Clearwater FL
Robert Schoer MD and Pathology DepartmentMorton Plant Mease Medical Center Clearwater FL
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