Gel shot vs standard injection: which quiets arthritic knees?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Signed and dated informed consent form * Stated willingness to comply with all study procedures and availability for the duration of the study * Male or female, aged ≥ 40 years * Clinical diagnosis of knee OA American College of Rheumatology criteria confirmed by radiology * Definite radiographic OA in the most symptomatic knee (target knee) at mild to moderate-stage (Kellgren-Lawrence grades 2 or 3) * Stable dose of analgesics for the past four weeks * NRS (11 points (0-10) pain intensity numerical rating scale) ≥ 4 in target knee, during the past week when walking * Body Mass Index (BMI) between 20-35 * For females of reproductive potential: use of adequate contraception must be used throughout the trial Exclusion Criteria: * Female participants who are pregnant, lactating or planning pregnancy during the course of the clinical investigation * Contraindications to PAAG-OA or Synvisc-One®, according to IB or Instruction for Use (IFU) * Previous intra-articular injection of polyacrylamide gel in the target knee * Previous intra-articular injection with hyaluronic acid or derivatives in target knee in the previous 6 months * Significant valgus/varus deformity of the knee, ligamentous laxity or meniscal instability * Other diseases in target knee than osteoarthritis * Intra-articular injection of any substance other than hyaluronic acid (e.g. corticosteroids) in the target knee within the last 3 months * Acute serious infection of any region that required hospital care or intravenous antibiotic treatment within the last 30 days, or oral antibiotic treatment within the last 14 days * Skin disease or infections in the area of the injection site * Infected or severely inflamed knees * History of sepsis in any joint or any clinical concern for a subacute infectious process in the target knee * History of surgery in the target knee within the past 6 months * Symptomatic osteoarthritis of the hips, spine or ankle, that interferes with the evaluation of the target knee * Planned surgery on any lower extremity * Clinically significant venous or lymphatic stasis present in the legs * Clinically apparent tense effusion or inflammation in the target knee * Suffering from any unstable or severe cardio-vascular disease * Any contraindication to intra-articular e.g. anticoagulant therapy or clinical concern for potential coagulopathy (e.g. liver disease) * Any foreign material in the target joint * Any significant medical condition (e.g. significant psychiatric or neurological disorders or active alcohol/drug abuse), any medical condition that is unstable/poorly controlled or other factors that may interfere with study participation * Treatment with systemic steroids * History of drug/alcohol abuse, mental dysfunction of other factors limiting their ability to cooperate fully * Change in physiotherapy within the previous month * Fibromyalgia * Inflammatory or other disease/condition which may affect joints (e.g. rheumatoid arthritis, psoriatic arthritis and ankylosing spondylitis among others) * Haemophilia * Any other condition that in the opinion of the investigator put a potential participant at risk or otherwise precludes participation in the trial * Known allergic reactions to components of Synvisc-One (avian protein) * Known allergic reactions to antibiotics (azithromycin and moxifloxacin) or local anaesthesia * Participation in any experimental device study within 6 months prior to enrolment, or participation in an experimental drug study within 1 month prior to enrolment