ABSTRACT Objective: The aim of this study was to investigate the effect of ultrasonography (USG)-guided Baker's cyst (BC) aspiration in the treatment of BC.

Design: A total of 40 patients presented to our polyclinic with the complaints of swelling at the back of the knee. The 40 patients were randomly divided into two groups: (I) aspiration group (n=20) and (II) control group (n=20). In the aspiration group, BC content was aspirated percutaneously under USG guidance, whereas no aspiration was performed in the control group. Additionally, the participants in both groups were trained on how to perform exercises and were also recommended to practice cold treatment for 15 min both in the morning and evening for 2 weeks. All the patients were followed up with USG at the first and third months, VAS, WOMAC, NHP , Lysholm and Cincinnati. The success of the treatment was demonstrated by the decrease in the width, length and area of the BCs and Lysholm, Cincinnati ,VAS, WOMAC and NHP scores.

Objective: The aim of this study was to investigate the effect of ultrasonography (USG)-guided Baker's cyst (BC) aspiration in the treatment of BC.

Design: This prospective study was conducted at Erzurum Atatürk University Medical Faculty Physical Medicine and Rehabilitation Department between January 2016 and June 2017 for a total period of 18 months. A total of 40 patients (11 males, 29 females) aged between 33-71 (mean age, 55.9 ± 9.6) years presented to our polyclinic with the complaints of swelling at the back of the knee. All the patients signed an informed consent form and the study was approved by the local ethics committee. (ERZURUM ATATUK UNIVERSITY MEDICAL FACULTY CLINICAL RESEARCH ETHICS COMMITTEE Date:03.12.2015 Meeting Number:8 Decision Number:24) Patients with a history of malignancy, coagulation disorder, and a neurological deficit and those receiving anticoagulant therapy were excluded from the study. The sample size was determined with a 95% confidence interval according to https://www.macorr.com/sample-size-calculator.htm website.

Prior to the procedure, all the patients were evaluated with grey-scale USG using an Esaote MyLab 60 USG device with a linear probe of 7.5 MHz. On USG examination, the area of transverse diameter(width-parallel to the knee joint), longitudinal diameter (length-perpendicular to the knee joint), and the USG area( from the widest place viewed) of BCs were calculated and recorded.

Clinical complaints of the patients, long-term complaints, and the history of medical, interventional, and surgical treatments were reviewed for each patient. Patients were also investigated for acute local or systemic infections.

The severity of clinical complaints was assessed using VAS, WOMAC knee osteoarthritis index, Lysholm knee scoring scale, Cincinnati knee rating system, and NHP. Patients with BC who had no contraindications for treatment and completed the WOMAC Knee osteoarthritis index, Lysholm knee scoring scale, Cincinnati knee rating system, VAS, and NHP and signed the patient consent form were included in the study. Patients were randomly divided into two groups by consecutive alternate allocation according to the time of admittance: (I) aspiration group (n=20) included the patients aspirated and (II) control group (n=20) included those who did not aspirated. In the aspirated group, the popliteal fossa areas were sterilized and BC content was aspirated from the popliteal fossa percutaneously under USG guidance with a 21-gauge needle (Figure 1). If the BC was septal, aspiration was performed from several different levels of the cyst so that the cyst content could be completely emptied. In contrast, no aspiration was performed in the control group. Additionally, the participants in both groups were trained on how to perform exercises and were also recommended to practice cold treatment for 15 min both in the morning and evening for 2 weeks.

After the aspiration, the patients were told how to exercise and practice cold treatment in the morning and evening for 2 weeks. Patients were discharged after a 30-min observation period following the procedure. Patients were allowed to apply bandages for 2 days after the procedure and were followed pre- and post-procedurally at the first and third months of treatment with WOMAC Knee osteoarthritis index, Lysholm knee scoring scale, Cincinnati knee rating system, VAS, and NHP and with USG. The appearance of BC at month 3 was examined on grey-scale USG and the length, width, and area of the cyst were recalculated. During the 3-month follow-up period, no additional treatment was performed in any patient. The success of the procedure was defined as reduction in BC width, length and area in sonographic measurements and decrease in the Lysholm knee scoring scale, Cincinnati knee rating system, VAS, WOMAC knee osteoarthritis index, and NHP scores.

Inclusion Criteria:

• To have baker's cyst..
• To comply with the treatment protocol
• Signing the information consent form

Exclusion Criteria:

• To have malignancy
• To have neurological deficit
• Those with coagulation disorders or those receiving anticoagulant therapy

: A total of 40 patients presented to our polyclinic with the complaints of swelling at the back of the knee. The 40 patients were randomly divided into two groups: (I) aspiration group (n=20) and (II) control group (n=20). In the aspiration group, BC content was aspirated percutaneously under USG guidance, whereas no aspiration was performed in the control group. Additionally, the participants in both groups were trained on how to perform exercises and were also recommended to practice cold treatment for 15 min both in the morning and evening for 2 weeks. All the patients were followed up with USG at the first and third months, VAS, WOMAC, NHP , Lysholm and Cincinnati. The success of the treatment was demonstrated by the decrease in the width, length and area of the BCs and Lysholm, Cincinnati ,VAS, WOMAC and NHP scores.

This prospective study was conducted at Erzurum Atatürk University Medical Faculty Physical Medicine and Rehabilitation Department between January 2016 and June 2017 for a total period of 18 months.

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