The purpose of this study is to assess the effects of joint effusion on proprioceptive status in patients with knee osteoarthritis (OA).

Proprioception is a sensory modality that provides feedback on the internal status of the body and enables us to perceive joint position and motion.

Osteoarthritis (OA), also called degenerative joint disease, is a major musculoskeletal condition characterized by loss of articular cartilage that leads to pain and loss of function. The most commonly affected joint is the knee, and OA may result in changes that affect not only intracapsular tissues, but also periarticular tissues, such as ligaments, capsules, tendons, and muscles. Many studies have examined the proprioceptive status of knee OA, and subjects with knee OA are known to have impaired proprioception compared with age-matched controls.

Joint effusion is a common symptom associated with chronic degenerative joint condition, but the effects of effusion on knee joint proprioception have not been investigated in detail.

A volume of 20 mL of normal saline was injected into the knee joint cavity of subjects in the experimental group under ultrasonographic guidance. Proprioceptive acuity was assessed by active repositioning of the lower limb using an electrogoniometer to measure knee joint position sense (JPS) under both non-weight-bearing and weight-bearing conditions twice, with a 20-min rest interval.

Inclusion Criteria:

Or at least two of criteria 2-6 established by the American College of Rheumatology (ACR):

1. Kellgren and Lawrence (K/L) grade ≥II
2. morning stiffness <30 min in duration
3. crepitus on movement of the knee joint
4. bony tenderness at the knee joint margins
5. palpable or visible bony enlargement
6. no palpable warmth.

Exclusion Criteria:

1. the presence of knee joint effusion determined by ultrasonography
2. a history of knee injury or surgery
3. a history of knee injection within 3 months
4. a history of inflammatory arthritis
5. taking anticoagulants
6. balance or gait disturbance
7. diabetes mellitus.