The Biologic Effects of Traction in Hip Arthroscopy (SS-41)

Abstract

<h3>Introduction</h3> The purpose of this study was to evaluate the effects of traction on the lower extremity during hip arthroscopy by perioperative monitoring of venous blood flow, nerve conduction, and markers of soft tissue injury, blood clots, and patient pain. <h3>Methods</h3> (In progress at the time of this report.) In a prospective, nonrandomized design 30 subjects who had elected to undergo hip arthroscopy that required traction for access to the central compartment of the hip joint were analyzed. Measurements of visual analog pain scale (VAS), creatine phosphokinase (CPK-MM), and D-dimer were obtained preoperatively (pre), postoperatively (post), and 5 days postoperatively (5d). Perioperative documentation included operating room time, traction time, and force of traction. The sample population was divided into two cohorts, a Doppler ultrasound group (DUG, n=15) and a somatosensory evoked potentials group (SSEP, n=15). DUG were monitored for venous blood flow at the level of the femoral and popliteal veins prior to traction, and following application and removal of traction. SSEP of the posterior tibial nerve (PTN) and the superficial peroneal nerve (SPN) were monitored intra-operatively in 5-15 minute intervals beginning prior to traction and continued through the end of surgery. <h3>Results</h3> (Preliminary results at the time of this report, n=19.) Average operating room time was 114.9 minutes. Traction was applied for an average of 26.5 minutes at an average of 57.1 lbs. With the application of traction, 15 of 15 subjects in DUG experienced >50% decreased blood flow of the popliteal vein and 13% (2 subjects) experience decreased blood flow at the femoral vein. Blood flow returned to baseline following removal of traction in all subjects. Average CPK-MM levels were: pre=81.5 ± 35.8 milliunits/mL, post=173.8 ± 130.5 milliunits/mL, and 5d=120.3 ± 71.5 milliunits/mL. Two subjects were D-dimer positive at baseline which remained positive through 5d post. At the time of this report 4 SSEP subjects were complete. One of four showed >50% decrease in amplitude of the PTN in both the operative and non-operative legs, which returned to normal within 10 minutes of knee flexion of both legs. There were no significant correlations determined between VAS, BMI, CPK-MM, traction time, or operating room time. <h3>Conclusion</h3> The Doppler ultrasound group demonstrated greater than 50% decrease in blood flow at the popliteal vein with the application of traction, which returned to normal after the removal of traction. SSEP demonstrated changes both with and without traction on both operative and non-operative legs of the posterior peroneal nerve. Consideration should be given for knee flexion of the contralateral leg when traction is discontinued for the protection of the peroneal nerve. There is variability in the soft tissue damage with hip arthroscopy, which is independent of time (under 2 hours), BMI, or correlations of VAS. Traction in the present form affects vascular and neurologic structure of the operative and non-operative extremity independent of time. A better method to create space in the central compartment and prevent harm to the soft tissue, vascular, and neural structures is needed.