The primary purpose of this study was to determine if cannabinoid use decreases narcotic consumption in patients undergoing total knee arthroplasty (TKA).

Subjects enrolled will be randomized into one of two groups either receiving the study drug or a placebo and will be followed for the first 6 weeks with regards to outcomes data.

Inclusion Criteria:

• Provision of signed and dated informed consent from
• Stated willingness to comply with all study procedures and availability to attend all required visits for the duration of the study.
• Male or Female
• Age 21-75
• Unilateral total knee arthroplasty at Colorado Joint Replacement
• All individuals will be screened for drug use (including cannabis) at their preoperative appointment
• Ability to take oral medication and be willing to adhere to the dronabinol regimen
• For females of reproductive potential: use of highly effective contraception for at least 1 month prior to screening and agreement to use such a method during study participation.
• For males of reproductive potential: use of condoms or other methods to ensure effective contraception with partner.

Exclusion Criteria:

• Narcotic use in the past 6 weeks
• Regular cannabis use in the past 3 months
• Major depression or anxiety disorders
• Documented psychiatric illness (e.g. bipolar, schizophrenia)
• Seizure disorder
• Current or previous history of drug and alcohol abuse
• Known allergic reactions to components of dronabinol
• Tobacco use in the past 90 days
• Treatment with another investigational drug
• Patients that cannot receive spinal anesthesia
• Patients that cannot receive the standardized multimodal pain medications (i.e. Tylenol, gabapentin and meloxicam)
• Patients that are not able to go home after leaving the hospital and require a short term rehabilitation facility