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.