A Pilot Feasibility Study of IM OXT on Fear of Pain and Trust in Physical Therapist During OP Rehabilitation After TKA

This study will examine the effect that a dose of intramuscular (IM) oxytocin (naturally occurring hormone) has on fear of pain and movement and trust in the physical therapist during outpatient rehabilitation after total knee replacement has been performed. Investigators will ask participants to answer questions about fear of pain and movement before several outpatient physical therapy session and investigators will ask participants questions about trust of the physical therapist several times after the outpatient physical therapy sessions.

The purpose of this study is to determine feasibility of this study design and identify barriers that altered design could bring to overcome these barriers in the design of a large, pragmatic, multi-center clinical trial. It is also designed to estimate the effect size and variance of the main outcome measures, trust and fear, in patients undergoing rehabilitation after total knee arthroplasty (TKA). The study team hypothesizes that intramuscular (IM) oxytocin, in a dose and time determined by a series of previous studies under this grant to target the brain, will enhance trust and reduce fear and that these will be associated with improved outcomes. Again, the study is not designed to test this hypothesis, but to gather the critical data necessary to test it in a large, multi-center clinical trial that would follow this grant.

Participants that have decided to undergo unilateral TKA, will come to the Pain Clinical Research Unit at least 48 hours prior to surgery to confirm consent and complete a series of questionnaires. Participants surgery, anesthesia, and postoperative medication and therapy treatment will be routine. On the first outpatient study visit participants will complete a questionnaire of fear about pain and receive an intramuscular injection of oxytocin or placebo in a randomized, double blind manner. At the end of this session participants will complete a questionnaire assessing the degree of trust in the therapist. Physical therapy be will routine, and the fear and trust questionnaires will be completed at the 2nd, 4th, 8th, and last physical therapy session as well as routine measures of progress and function. The primary outcome measure is assessment of effect size and variability of the trust and fear questionnaires on the 1st and 2nd visit.

Eligibility Criteria:
Inclusion Criteria:

1. Male or female \> 18 and \< 75 years of age, Body Mass Index (BMI) \<40.
2. Generally in good health as determined by the Principal Investigator based on prior medical history, American Society of Anesthesiologists physical status 1, 2, or 3. Scheduled for unilateral TKA and postoperative physical therapy at Davie Medical Center.
3. Normal blood pressure (systolic 90-140 mmHg; diastolic 50-90 mmHg) resting heart rate 45-100 beats per minute) without medication or for those with hypertension, pressure controlled with anti-hypertensives and with a resting heart rate 45-100 beats per minute.
4. Female subjects of child-bearing potential and those \< 1 year post-menopausal, must be practicing highly effective methods of birth control such as hormonal methods (e.g., combined oral, implantable, injectable, or transdermal contraceptives), double barrier methods (e.g., condoms, sponge, diaphragm, or vaginal ring plus spermicidal jellies or cream), or total abstinence from heterosexual intercourse for a minimum of 1 full cycle before study drug administration.

Exclusion Criteria:

1. Hypersensitivity, allergy, or significant reaction to any ingredient of Pitocin®
2. Any disease, diagnosis, or condition (medical or surgical) that, in the opinion of the Principal Investigator, would place the subject at increased risk (active gynecologic disease in which increased tone would be detrimental e.g., uterine fibroids with ongoing bleeding), compromise the subject's compliance with study procedures, or compromise the quality of the data
3. Women who are pregnant (positive result for urine pregnancy test at screening visit), women who are currently nursing or lactating, women that have been pregnant within 2 years
4. Subjects with neuropathy, chronic pain, diabetes mellitus, or taking benzodiazepines or pain medications on a daily basis.