The purpose of this randomized, placebo controlled, single blind study is to determine if postoperative pain levels, as measured by a verbal numeric pain rating scale (VNRS), are reduced with the administration of IV acetaminophen when compared to a control group. Particular focus will be on the postoperative opioid consumption. In addition, we will ascertain if the total time the participant is in the PACU differs in those who receive the IV acetaminophen versus those who do not.

This is a randomized, placebo controlled, single blind study of intravenous (IV) acetaminophen in a postoperative arthroscopy patient population. Although use of this medication as a non-narcotic analgesia has been validated in other patient populations such as post operative pelvic and abdominal surgeries, it has not been demonstrated in those who have recently undergone knee arthroscopy with or without chondroplasty. In this study all participants will be injected with a standard of care intra-articular dose of ropivacaine HCl, .2% (Naropin) prior to transfer to the Post Anesthesia Care Unit (PACU). Each will be randomized 1:1 to receive IV acetaminophen in 100ml of 0.9% NS (treatment group) or a 100 ml 0.9 % NS placebo (control).

The PACU nursing staff will periodically ascertain the participants' pain scores on a 0-10 scale. All other pain medication or related treatment will be recorded. Statistical analysis will be done to determine if there is a difference in pain scores between the treatment versus control group. Further evaluation will examine if opioid consumption and total time in PACU differs between groups.

Inclusion Criteria:

• Is scheduled for knee arthroscopy with or without chondroplasty.
• Scheduled arthroscopy procedure will not include ligament repairs or ligament reconstructions and/or bone cutting or fixation procedures.
• Has not received any acetaminophen (IV, PR, PO) within at least 8 hours of the initiation of surgery.
• Is willing and able to sign an informed consent.

Exclusion Criteria:

• Is undergoing arthroscopy for ligament repairs/reconstructions and bone cutting or fixation procedures
• Has self-reported and/or documented previous hypersensitivity to acetaminophen.
• Has self-reported and/or documented history of hepatic disease or impairment.
• Pre-operative calculated creatinine clearance (CrCL) less than 40 ml/min.
• Has a medical history of alcohol abuse and/or currently drinks more than 3 alcoholic beverages per day.
• Has a medical history of substance dependence (i.e. prescription analgesics or illegal drugs such as cocaine, heroin, etc…). May be self-reported or maybe per the judgment of the physician PI/Sub-I.