Dynamic positioning of scoliotic patients during spine instrumentation surgery

Evaluation of a novel Dynamic Positioning Frame (DPF) for scoliosis surgery to improve presurgical correction.

To assess a DPF for scoliosis surgery and demonstrate how its design offers additional presurgical correction of the 3-dimensional deformity.

Patient positioning is an important step in scoliosis surgery. Although current positioning frames focus on supporting the patient and keeping the abdomen pendulous to reduce blood loss, not much has been carried out to explore the aspect of dynamic positioning during surgery. When lying prone, there is some spontaneous correction of the scoliotic deformity owing to gravity and anesthesia.

Trunk 3-dimensional geometry and pressure at the patient-cushion interface were measured for 12 unanesthetized patients in various positions-standing (PI), lying prone on the DPF (PII), lying prone on the DPF with applied corrective forces (PIII), and lying prone on the Relton-Hall (R-H) frame for comparison (PIV).

Spine height increased significantly in prone as compared with that in standing position. When lying on the DPF with corrective forces, there was an improvement in the patients' transverse plane deformity and rib hump with greater retention of kyphosis. There was also an improvement in the rib hump as compared with that in the R-H frame. Higher pressures were recorded on the DPF as compared with the R-H frame, but were reduced to similar values when larger cushions were used.

The DPF provides a novel way of modifying the patient's position preoperatively and intraoperatively. Dynamic patient positioning, coupled with applied corrective forces, allows for increased reduction of the scoliotic deformity as compared with the R-H frame. Further investigation is required to optimize cushion placement and thus, insure safe patient-cushion interface pressures.