Podium Presentation Abstracts
Summary: TrUGA is an effective method for selection of fusion levels and may help to save L4 when compared to traditional x‐ray methods in surgical treatment of Lenke type 3 and 6 curves.
Introduction: Several studies have shown the importance of saving L4 and stopping fusion lowest at L3 in patients with structural lumbar curves. However, fusing L4 may be necessary in many patients with structural lumbar curves (i.e, Lenke type 3 and 6) when the selection of fusion levels are done by using the traditional x‐ray methods (TXR) (side bending, fulcrum and traction). The aim of this retrospective study was to evaluate if TrUGA helps to save L4 in patients with Lenke type 3C and 6C patients.
Methods: Eighty‐nine consecutive patients (77 female and 12 male) with AIS Lenke type 3C (46 patients) and 6C (43 patients) curves underwent an instrumented posterior spinal fusion. The selection of fusion levels was done using the criteria of “stable vertebrae to be (SVTB)” and it was defined as the uppermost vertebrae of the lumbar curve curve that is not bisected by CSVL at the standing A‐P film, but becomes parallel to sacrum and is bisected by CSVL or CSVL passes through the medial side of the concave pedicule at the TXR or TrUGA. The disc wedging under “SVTB” should be corrected to paralel and rotation should be corrected at least one to 2 grades. Preoperative radiological evaluation included standing A‐P, lateral, supine lateral bending, traction radiographs, and also supine TrUGA. “SVTB” was determined by using TXR and TrUGA. Then pre‐postop and follow‐up curve magnitudes, LIV tilt, disc wedging below LIV and CSVL‐LIV distance were measured (Table 1).
Results: The average follow‐up was 5.4 years. Average age was 15.5 years. Pedicle screw constructs (PS) were used in all patients. LIV was L3 in 85 patients while it was L4 in 4 patients. Using the same selection criteria L3 was LIV according to both the TXR and TrUGA in 39 cases (44%) and fusion was stopped at L3. In 46 (52%) cases, TXR determined L4 as LIV while in all those patients L3 was the LIV according to TrUGA and fusion was stopped at L3 in all patients. LIV was L4 according to both methods in 4 (4%) patients and fusion was stopped at L4. None of the patients required additional surgery for decompensation and adding on.
Conclusion: TrUGA is an effective method for selection of fusion levels and may help to save L4 when compared to TXR in surgical treatment of Lenke type 3 and 6 curves.