Patient Cushion Interface Pressure during Scoliosis Surgery

  • Author / Creator
    Behzadi Fard, Negar
  • Scoliosis is the deformation of the spine and, in some cases, surgery is suggested in order to correct the curvature and prevent progression. During scoliosis surgery, the patient is positioned on the surgical frame face down in such a way that the hips and chest are placed over cushions. Lateral femoral cutaneous nerve (LFCN) compression is a complication which is seen after surgery in some cases. Tingling, numbness and pain are the symptoms some patients have as a result of LFCN injury and it is hypothesized that high intraoperative patient cushion interface pressure may cause LFCN compression. The main objective of this work is to quantify the pressure at the patient cushion interface during surgery. To measure the pressure during scoliosis surgery, a Force Sensing Array (FSA) pressure mapping system including a set of four pressure mats is used in the operating room. Previous research on FSA pressure mats show a number of errors, so the mats were examined in the lab to see if this error affects the data measurements in the operating room. Data from a total of twenty-three patients was collected in the operating room. The patients were positioned on the operating table with the pressure mats on the cushions. In addition to pressure measurement, the patient’s body mass index (BMI) and the duration of the surgery were recorded. LFCN injury was determined after surgery by physical examination using light touch sensation tests and asking the patient if they feel any numbness, tingling or pain. Results from pressure measurements indicate that the average pressure for patients with LFCN injuries is 32 mmHg and 29.5 mmHg for the left and right hips, respectively. By comparison, those who did not have LFCN problems experienced pressures of 27 mmHg and 26 mmHg for the left and right hip, respectively. There was a significant difference between the duration of the surgery for patients with (350 minutes) and without (264 minutes) LFCN injury. BMI was also evaluated as a risk factor for LFCN injury but there were no significant findings. Somatosensory evoked potentials (SSEPs) recorded during the surgery were analyzed to see if they show any abnormal signals in patients with LFCN injury. A detailed analysis of the SSEPs is reserved for future work. It is concluded that the duration of the surgery was the only significant factor in determining LFCN injury during scoliosis surgery.

  • Subjects / Keywords
  • Graduation date
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
    • Department of Mechanical Engineering
  • Specialization
    • Mechanical Engineering
  • Supervisor / co-supervisor and their department(s)
    • Duke, Kajsa.K (Mechanical Engineering)
  • Examining committee members and their departments
    • Vette, Albert H (Mechanical Engineering)
    • Duke, Kajsa K (Mechanical Engineering)
    • Rouhani, Hossein (Mechanical Engineering)