The Baker cyst (BC), also known as the popliteal cyst or parameniscal cyst, is a fluid-filled sac that commonly develops in the posterior aspect of the knee, between the semimembranosus and medial head of the gastrocnemius. It is a common complication of knee osteoarthritis, and can also be associated with other conditions such as rheumatoid arthritis, gout, and meniscal tears.

BCs are typically asymptomatic, but can cause pain, stiffness, and swelling in the back of the knee. In severe cases, they can rupture, leading to inflammation and pain in the calf.

Physiotherapy is a common treatment for BCs, and has been shown to be effective in reducing size and symptoms. Intermittent vacuum therapy (IVT) is a type of physiotherapy that involves applying suction to the affected area. IVT is thought to work by increasing blood flow and lymphatic drainage, which can help to reduce inflammation and swelling.

This study aims to evaluate the effectiveness of IVT in the treatment of BCs. A total of 65 patients with knee osteoarthritis and BCs will be recruited and randomized to either a control group or an IVT group. The control group will receive standard physiotherapy treatment, while the IVT group will receive IVT in addition to standard physiotherapy treatment.

All patients will be assessed at baseline and after 10 days of treatment using a variety of clinical and functional measures, including the echo volume of the BC. The results of the study will be used to determine whether IVT is an effective treatment for BCs.

This study is designed to contribute to the existing body of knowledge on the treatment of BCs. The results of the study will be of interest to clinicians, researchers, and patients.

The study was a prospective, randomized, controlled, single-blind study conducted at the Balneal and Rehabilitation Sanatorium Techirghiol (BRST) in Romania. A total of 65 patients with knee osteoarthritis (OA) and Baker's cysts (BCs) were enrolled in the study. The patients were randomly assigned to either an intermittent vacuum therapy (IVT) group or a control group.

The IVT group received IVT in addition to standard physical therapy, while the control group received standard physical therapy only. IVT was performed daily for 30 minutes using a Vacumed device. The device consists of an airtight vacuum chamber and a pump connected to a pressure control system. During vacuum treatments, participants were asked to lay themselves comfortably in a supine position. The lower body was positioned in the vacuum chamber, which was sealed around the participant's trunk with a cuff at the level of the umbilicus to allow application of negative pressure. Negative pressure cycles are created by alternating between removing air and venting the chamber to atmospheric pressure.

The standard physical therapy program consisted of a general warm mud bath (20 minutes at 38 degrees Celsius), hydrokinetotherapy in saline water from Lake Techirghiol by a certified physical therapist (20 minutes at 35 degrees Celsius), massage therapy for paravertebral muscles, shoulder and pelvis girdle, kinesio-therapy with a standard program for peripheric joints for 30 minutes.

All patients were assessed at baseline and after 10 days of treatment using a variety of clinical and functional measures, including the volume of the BC. Data on demographics and clinical conditions was gathered. The investigators collect the next features: sex, age, level of education, occupation, environment, degree of functional deficit, body mass index (BMI) and Kellgren-Lawrence classification.

Also, scores for the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Functional Independence measurement (FIM), the Fall Risk Score, and the Visual Analogue Scale (VAS) were recorded at baseline and after 10 days.

All patients were recruited at the BRST by a clinician blinded as to group allocation. Each study group was composed through random allocation of the total sample with a 1:1 allocation ratio that was reported to patients by a different researcher, who was neither the one who performed the treatment nor the one who performed the evaluation, through a pre-specified allocation list who was concealed in a password-protected computer file.

Of the total of 102 patients who were presented for hospitalization in the BRST between November and December 2022, only 65 completed the participation conditions, being grouped into two groups of 33 and 32, respectively. Due to the relatively small number of patients, the statistical approach was a non-parametric one: Independent Samples Mann Whitney U test, Independent Sample Median Test, Reb test Samples Wilcoxon Signed Rank test and Chi-Square test.

Inclusion Criteria:

• free consent based on explaining and understanding all related procedural steps;
• age over 18 years;
• diagnosis of knee osteoarthritis with Baker Cyst.

Exclusion Criteria:

• neurological conditions
• rheumatological conditions
• trauma
• a history of knee or lower extremity joint surgery,
• a history of hip or ankle pain
• a history of steroid injection in the previous three months,
• conditions that would be contraindicated by Intermittent Vacuum Therapy.