Analysis of surgical treatment of severe angular kyphosis with keeping the spinal cord length constant in osteotomy area

Abstract

Objective: To explore the surgical methods and clinical outcomes of severe angular kyphosis with the length of the spinal cord constant in the osteotomy area. Methods: Clinical data from 20 patients with severe angular kyphosis who underwent surgical treatment from January 2017 to December 2020 in the Department of Spinal Surgery,Hangzhou Xiaoshan District Hospital of Traditional Chinese Medicine were retrospectively analyzed. There were 11 males and 9 females, aged (28.5±8.9) years (range:17 to 46 years).There were 15 cases with congenital angular kyphosis,5 cases with tuberculous angular kyphosis.The angle of kyphosis was (107.1±12.9)° (range:93.2° to 131.4°).Frankel classification:2 cases with grade B,4 cases with grade C,3 cases with grade D.The kyphotic vertex is located at the T9 to T12 segments.Pedicle screws were placed in 3 or 4 adjacent segments at the proximal and distal kyphosis apex of the patients using a surgical navigation system.Piezosurgery combined with a grinding drill was used to complete the osteotomy in the apical vertebral region.Titanium mesh or artificial vertebral body was implanted,and the osteotomy surface was closed using this as the fulcrum to complete osteotomy.Spinal X-ray examination was performed before surgery,immediately after surgery and at the last follow-up,and sagittal and coronal Cobb angle,sagittal and coronary balance parameters,anterior vertebral height,posterior vertebral height,and spinal cord length were measured.Pulmonary function,visual analogue scale (VAS),and Oswestry's disability index (ODI) were collected and estimated before and after treatment.The analysis of variance of repeated measurement data was used for each evaluation index before and after treatment,and the t test was used for pairwise comparison. Results: All patients successfully completed surgery,with artificial vertebral body in 11 cases and double titanium mesh in 9 cases.The follow-up time was (28.2±2.3) months (range:26 to 31 months).Sagittal vertical axis improved from (46.9±13.7)mm(range:21.7 to 75.7 mm) before surgery to (10.7±5.5)mm (range:3.6 to 28.1 mm) after surgery,and (11.0±5.7)mm(range:3.6 to 29.3 mm) at the last follow-up,the differences were statistically significant compared to before surgery (all P<0.01).The mean kyphotic Cobb angle was corrected from (107.1±12.9) ° (range:93.2 ° to 131.4°) before surgery to (30.6±8.5) ° (range:20.0 ° to 47.8 °) after surgery (all P<0.01),and (32.1±8.7) ° (range:18.2 ° to 50.8°) at the last follow-up,the differences were statistically significant compared to before surgery(all P<0.01).The anterior vertebral height improved from (14.2±2.9)mm(range:11.04 to 23.6 mm) before surgery to (45.3±7.5)mm(range:29.4 to 56.5 mm) after surgery,and (44.3±6.8)mm(range:29.6 to 56.0 mm) at the last follow-up,the differences were statistically significant compared to before surgery (all P<0.01).The posterior vertebral height was improved from (51.8±5.3)mm (range:43.1 to 61.4 mm)before surgery to (57.6±4.7)mm (range:45.7 to 64.1 mm)after surgery,and (56.3±5.0) mm (range:49.7 to 68.5 mm) at the last follow-up,the differences were statistically significant compared to before surgery (all P<0.01).The spinal cord length of the osteotomy segment was (73.1±12.0)mm (range:56.8 to 98.4 mm) before surgery and (74.8±12.8)mm (range:53.5 to 100.2 mm) after surgery and (75.2±13.7)mm (range:53.9 to 102.4 mm) at the last follow-up,the difference was not statistically significant among them(F=0.144,P=0.866).The ODI and VAS scores improved significantly after surgery and at the last follow-up,and the differences were statistically significant (all P<0.01). Conclusion: The posterior vertebral column resection technique combined with titanium mesh or an artificial vertebral body implant for the treatment of severe angular kyphosis can significantly improve the kyphosis,neurological function,and life quality of patients without affecting the length of the spinal cord.