PRP vs Corticosteroid in Baker's Cyst

This is a Prospective study with Randomized patients into either Ultrasound-guided Platelets-Rich-Plasma injection and Ultrasound guided Corticosteroid Injection, with 3 months and 6 months follow ups after aspiration at our institution. There will be 25 patients in each group, including any patient with symptomatic baker's cyst.

The treatment of Baker's Cysts are based on its presentation, asymptomatic cysts are currently managed conservatively, symptomatic cysts are treated with joint aspiration and Corticosteroid injection, which have shown according to literature a decrease of the cyst size in approximately two-thirds of patients within 2-7 days but only complete disappearance in approximately 7 %. Ultrasound guided cyst aspiration and Corticosteroid injection are also used with reduction of cyst's size with recurrence in 6 months of 19%. Surgical options to remove the cyst include, Open Resection with a recurrence of 50%, 25% of patients have motion limitation recurrence, 37% have wound healing problems or tense swelling of the calf and 75% of patients have joint pain lasting more than 2 days. Arthroscopic resection, with no recurrence in ultrasound performed 6 and 12 months after procedure, pain lasting more than 3 days in 28% of patients, mild hematoma in 7% of patients and 7% where converted into an open procedure There is no study using ultrasound guided aspiration with platelet-rich-plasma injection (PRP). The rationale for the use of PRP is the belief that the additional platelets will exponentially increase the concentration and release of multiple growth and differentiation factors at the injury site to augment the natural healing process9. PRP does not have any described negative side effect due to the fact that is being prepared from subject's own blood, with no risk of allergy or cross infection, relatively easy for a practiced clinician, and reproducible.

Patients will be asked to stop taking any type of anti-inflammatory medication from 7 days before the procedure to 2 weeks after and fasting for 3 hours before the procedure. At the moment of the procedure, the radiology team will draw 60ml of venous blood from the patient, the blood will be processed with different components of the PRP kit and centrifuged in the SmartPrep PRP machine, to obtain the PRP. The patient is then scanned prone using a linear 14 or 9 megahertz (MHz) transducer. A 20 Gauge spinal needle is usually employed for purposes of aspiration. Sterile saline will be used to confirm needle placement in the cyst in lieu of lidocaine and then inject the PRP by the radiologist.

Patients will be asked to stop taking any kind of anti-inflammatory medication from 7 days before the procedure to 2 weeks after but fasting in this group won't be required. An ultrasound guided aspiration and triamcinolone (40 mg) diluted with lidocaine without epinephrine and ropivacaine will be used to anesthetize the tissues down to the cyst (including within the cyst for steroid injections). A compression bandage will be placed locally for 7 days. Investigators will monitor any side effect from the injection and treat the patients per standard care - this can include prescription of analgesics.

Outcome measure will be determined through the use of the Visual Analogue Score (VAS) and the Rauschning and Lindgren criteria which are used to clinically evaluate the presence of the popliteal cysts, pain, posterior sense of tension in the popliteal fossa and its clinical importance for range of motion reduction. The Knee Injury and Osteoarthritis Outcome Score (KOOS) will be used to assess short and long term outcome of knee related conditions.

Outcome measure will be determined through the use of the Visual Analogue Score (VAS) and the Rauschning and Lindgren criteria which are used to clinically evaluate the presence of the popliteal cysts, pain, posterior sense of tension in the popliteal fossa and its clinical importance for range of motion reduction. The Knee Injury and Osteoarthritis Outcome Score (KOOS) will be used to assess short and long term outcome of knee related conditions.

All disease signs and symptoms experienced by the patient, as defined as an Adverse Event (AE), Treatment Emergent Adverse Event (TEAE), Serious Adverse Event (SAE), and Unexpected Adverse Device Effect (UADE), will be recorded from questionnaires during each study visit.

All disease signs and symptoms experienced by the patient, as defined as an Adverse Event (AE), Treatment Emergent Adverse Event (TEAE), Serious Adverse Event (SAE), and Unexpected Adverse Device Effect (UADE), will be recorded from questionnaires during each study visit.

Inclusion Criteria: Patients at least 18 years old. Patients with baker's cyst who also present with at least one of the following: swelling, local pain or discomfort, limited range of motion or any other symptom directly caused by the baker's cyst. Exclusion Criteria: Patients younger than 18 years old Local or Systemic active infection Active cancer treatment Immunodeficiency Diabetes Hypersensitivity or allergy to Corticosteroid or Lidocaine

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