A comparative study of the influence of Halo-gravity and Halo-pelvic traction on osteotomy grades in severe spinal deformities

English Keywords:Scoliosis  Halo-gravity traction  Halo-pelvic traction  Osteotomy grade  Severe spinal deformity  Predictive model

English Abstract:

  【Abstract】 Objectives: To evaluate the influence of preoperative traction on osteotomy grades, and to compare the therapeutic effects of halo-gravity traction(HGT) and halo-pelvic traction(HPT) in patients with severe spinal deformities. Methods: We retrospectively reviewed 60 patients with severe spinal deformities who underwent preoperative traction followed by posterior spinal osteotomy and fusion between August 2008 and November 2019. There were 22 males and 38 females, aged 8-33 years(19.8±5.9years). Patients were assigned to the HGT group(n=37) or the HPT group(n=23) according to the traction method used. Full-length standing radiographs were used to measure the sagittal and coronal Cobb angles before traction, at the end of traction, and at 48-month postoperative follow-up. Sagittal deformity angular ratio(SDAR) was calculated based on the Cobb angle and the number of involved segments. The kyphosis correction rate was also calculated. An osteotomy-grade prediction model was used to evaluate changes in the predicted osteotomy grade after traction. Inverse probability of treatment weighting(IPTW) was applied to compare the two traction strategies with respect to osteotomy grade and correction outcomes. Results: All 60 patients completed the treatment successfully. Before traction, the mean sagittal kyphotic Cobb angle was 131.82°±30.29°, and the mean coronal Cobb angle was 132.70°±28.77°. The predicted osteotomy grade was 5.10±0.92. At the end of traction, the sagittal kyphotic Cobb angle was 97.56°±33.54°, and the coronal Cobb angle was 100.93°±30.93°. The predicted osteotomy grade was 4.14±1.20, which was significantly lower than that before traction(P<0.001). The actual osteotomy grade was 4.34±0.98, also significantly lower than that before traction(P<0.001). After IPTW adjustment, the sagittal Cobb angle in the HGT group decreased from 133.48°±23.68° pre-traction to 111.23°±29.35° post-traction, whereas in the HPT group it decreased from 134.96°±40.89° to 75.07°±25.49° post-traction. The two traction methods achieved similar reductions in osteotomy grade(P>0.05). However, HPT produced greater improvement in SDAR(P=0.014), which also yielded a higher kyphosis correction rate than HGT(P<0.001). Conclusions: Preoperative HGT and HPT can both reduce the osteotomy grade required for surgical correction in severe spinal deformity. HPT provides better sagittal correction and kyposis corrective rate than HGT.