Transient electric changes immediately after surgical trauma

CONTEXT: Electric stimulation is frequently used to promote soft tissue healing, although we do not have a complete understanding of the tissue's electromagnetic properties. OBJECTIVE: To measure the transient electric changes in skin and muscle tissue immediately after trauma. DESIGN: 1-group time series. SETTING: Climate-controlled operating room in a public urban hospital. PATIENTS OR OTHER PARTICIPANTS: Eleven participants (8 females, 3 males) with a mean age of 65.18 +/- 11.36 years undergoing total hip arthroplasty. INTERVENTION(S): An incision approximately 10 cm distal to the posterior superior iliac spine extended distally over the greater trochanter and along the lateral limb. The incision was completed in 2 cuts: (1) skin and subcutaneous fat and (2) muscle tissue. MAIN OUTCOME MEASURE(S): Three measurement sessions were performed with an electrometer before and after a skin incision and after a muscle incision. Potential differences and current intensity were measured immediately after acute trauma to determine the transient electric changes associated with soft tissue injury. RESULTS: The electric potentials were significantly more negative after the skin incision (P = .036) and skin plus muscle incision (P = .008; preincision = 0.001 +/- 0.015 V, skin incision = -0.127 +/- 0.134 V, skin plus muscle incision = -0.192 +/- 0.153 V). Current intensity changed significantly after the skin plus muscle incision (P = .008; preincision = 0.046 +/- 0.112 pA, skin incision = -0.803 +/- 0.904 pA, skin plus muscle incision = -1.708 +/- 1.302 pA). CONCLUSIONS: Soft tissue trauma generated negative transient electric changes.