Gonarthrosis is a frequent cause of knee pain and mostly related to altered function of the knee. Intra-articular injections are a valuable noninvasive medical treatment of choice for pain management and functional enhancement. This study aims to investigate the effects of intra-articular injections without local anesthesics which are well known to be chondrotoxic. For this purpose, functional data of the patients who received intra-articular injections have been collected and analyzed.

Intra-articular knee injections are commonly used treatment method. It is preferred to relieve the pain and functional limitation due to knee osteoarthritis. Studies have shown the benefit of intra-articular injections, including intra-articular sterile saline injection alone. In addition, studies have shown chondrotoxic effects of local anesthetics and corticosteroids such as triamcinolone. Local anesthetics are often added to the injection in intra-knee injections. Many previous studies stated that anesthetic agents were mixed with corticosteroid and NSAID intra-articular injections but not in this study. This creates confusion on which preparation is effective on pain and function. The aim of this study is to compare pain-reducing and function-improving effects of intra-articular injection with corticosteroids or NSAIDs, while avoiding local anesthetics whose chondrotoxic effects have been confirmed. In order to reveal the unmasked effect, an intra-articular saline injection group was introduced as a sham treatment. Thus, a study with a level of evidence 1 will make a significant contribution to the literature.

Patients who applied to the outpatient clinic and who were diagnosed with primary gonarthrosis by clinical and radiographic examinations have been randomized to four different groups by closed-envelope method following taking the informed consent. Accordingly, nonsteroidal anti-inflammatory (NSAI) drugs have been prescribed to all diagnosed patients. Demographic data of the patients have been noted and randomized into four equal groups of thirty individuals each. Afterwards, the first group received NSAID treatment, the second group received intra-articular methylprednisolone, the third group received intraarticular tenoxicam, and the fourth group received intra-articular sterile saline injection. All eligible patients have been given one random envelope by the secretary, then proceeded to the injection room with envelopes closed. The orthopedic technician prepared the injection depending on the information inside the envelope then the syringe is covered with opaque plaster or foil. Then, an injection was applied by the physician blindly. The patients' visual analog score(VAS) pain form and WOMAC scores are collected in each follow-up. Following the data has been obtained by an independent data recorder, all data have been saved to the database and statistical results were analyzed. According to the posthoc power analysis, the number of patients can be revised for statistical power.

Inclusion Criteria:

• Patients older than 18 years old
• Diagnosed as Osteoarthritis ( in weight-bearing standing Antero-Posterior and Lateral knee plain radiographs)

Exclusion Criteria:

• Patients refuse to enroll in the study voluntarily
• Patients refuse to give informed consent
• Patients who have received physiotherapy and/or intraarticular injection in the last 6 months.
• Patients who have used supporting brace treatment in the last 6 months
• Patients did not attend routine follow-up visits.
• Patients experienced any allergic reaction to the administered drug

Even recruitment has been closed this study is still on progress. We are willing the share all our available data for future studies.

Study Protocol will be available following the paper has been published.

patients were not aware of the ingredient of the injection they had received Care providers were not aware of the ingredient of injection during application