Abstract
Introduction
Pedicle screw fixation commonly uses a manual probe technique for preparation and insertion of the screw. However, the accuracy of obtaining a centrally located path using the probe is often dependent on the experience of the surgeon and may lead to increased complications. Fluoroscopy and navigation assistance improves accuracy but may expose the patient and surgeon to excessive radiation. DSG measures electrical conductivity at the tip and provides the surgeon with real-time audio and visual feedback based on differences in tissue density between cortical and cancellous bone and soft tissue. The authors investigated the effectiveness of DSG for training residents on safe placement of pedicle screws.
Methods
15 male cadaveric thoracolumbar spine specimens were fresh-frozen at the time of expiration. Residents were assigned 3 specimens each and randomised by pedicle side and order of technique for pedicle screw placement (free-hand versus DSG). Fluoroscopy and other navigation assistance were not used for pedicle preparation. All specimens were imaged using CT following insertion of all pedicle screws. The accuracy was assessed by a senior radiologist and graded as within (≤ 2mm breach) or outside (> 2mm breach) the pedicle.
Results
15 specimens were dissected in standard fashion to expose the thoracolumbar spine (T7-L5). 5 residents were randomised and assigned 3 specimens each to prepare bilateral pedicles from T8 to L5 (60 pedicles per resident) using either PediGuard or free-hand technique. A total of 249 pedicle screws were placed. Post-procedure CT scans demonstrated 214 (85.9%) screws within the pedicle. Breach rate for the DSG group was 8.2% and 19.7% for the non-DSG group, with an overall reduction of 58% (p=0.025)
Conclusion
The use of Dynamic Surgical Guidance decreased the pedicle screw placement learning curve in residents, while improving breach rate by 58%. This study demonstrates that DSG has the potential for resident education and refinement in operative technique.
