The purpose of this study is to determine whether intra-articular injection of botulinum toxin is effective in the treatment of chronic knee paindue to arthritis.

Chronic knee pain unresponsive to oral medications and intra-articular corticosteroids and viscosupplements is an important treatment problem, especially for the young, very old and those with complex medical problems that preclude joint reconstructive surgery. We hypothesized that intra-articular botulinum toxin could provide important joint pain relief in these patients. This is a prospective, double blined, placebo controlled 6month trial with an open label extension phase when pain returns to baseline levels (re-injection with 100units of botulinum toxin and 6 months followup thereafter.

Comparisons: Intra-articular injection of bootulinum toxin type a will be compared to intra-articular injection of lidocaine the saline.

Inclusion Criteria:

• Male or female subjects, 18 years of age or older.

  • Written informed consent and written authorization for use or release of health and research study information have been obtained.
  • Subject has chronic Knee pain for more than 1 year.
  • Subject has pain >4.5 on numerical rating scale of 0 to 10.
  • Ability to follow study instructions and likely to complete all required visits.
  • Negative urine pregnancy test on the day of treatment prior to the administration of study medication (for females of childbearing potential if applicable)
  • Patients previously treated with intra-articular corticosteroid or viscosupplementation injections.
  • Patients with rheumatoid arthritis must have failed therapy with standard DMARDs (disease modifying anti-rheumatic drugs) and anti-TNF agents unless they have a contraindication to TNF blockers.
  • Patients who were considered not to be candidates for Knee joint replacement because of young age, abnormalities in periarticular tissues or because of co-morbid conditions.
  • Must be ambulatory and able to perform sit to stand.

Exclusion Criteria:

• Use of aminoglycoside antibiotics, curare-like agents, or other agents that might interfere with neuromuscular function.
• Any medical condition that may put the subject at increased risk with exposure to botulinum neurotoxin including diagnosed myasthenia gravis, Eaton-Lambert syndrome, amytrophic lateral sclerosis, any other disorder that might interfere with neuromuscular function or the presence of severe peripheral neuropathy.
• Females who are pregnant, breast-feeding, or planning a pregnancy during the study or who think that they may be pregnant at the start of the study, or females of childbearing potential who are unable or unwilling to use a reliable form of contraception during the study.
• Known allergy or sensitivity to any of the components in the study medication.
• Evidence of recent alcohol or drug abuse.
• Infection at injection site or systemic infection (postpone study entry until one week following recovery.
• Known, uncontrolled serious systemic disease and/or life expectancy less than 12 months.
• Concurrent participation in another investigational drug or device study or participation in the 30 days immediately prior to study enrollment.
• Any condition or situation that, in the investigator's opinion, may put the subject at significant risk, confound the study results, or interfere significantly with the subject's participation in the study.
• Patients whose pain is rated as less than 4.5 on a 10 point Numerical Pain Rating scale at the screening visit
• Patients on coumadin or heparin because of increased risk of bleeding in the joint
• Serious or unstable psychiatric disease or cognitive impairment that would limit evaluation of response to treatment.