Failure of Posterior Lower Lumbar/Lumbosacral Hemi‐Vertebra Resection: An Analysis of Reasons and Revision Strategies

OBJECTIVE: To investigate the causes of failed primary surgery and the revision strategies for congenital scoliosis (CS) patients with lower lumbar/lumbosacral (LL/LS) hemi‐vertebra (HV). METHODS: Fifteen CS patients with LL/LS HV (seven females and eight males) with a mean age of 20.4 ± 10.4 years undergoing revision surgery in our center were retrospectively reviewed. The radiographic parameters including Cobb angle, distance between C(7) plumb line and center sacral vertical line (C(7)PL‐CSVL), thoracic kyphosis (TK), lumbar lordosis (LL) and sagittal vertical axis (SVA) were assessed at pre‐revision, post‐revision and the last follow‐up. The causes of failure in primary operation, and radiographic and clinical outcomes of revision procedures were analyzed. RESULTS: The revision rate of patients undergoing LL/LS HV resection and correction surgery was 11.4%. The average time interval between primary surgery and revision surgery was 18.2 ± 10.6 months. The operation duration and estimated blood loss of revision surgery were 194 ± 56 min and 326 ± 74 ml, respectively. Reasons for failed primary operations were as follows: internal fixation fracture in 10 cases, curve progression in two cases, implant loose in two cases and post‐operative coronal imbalance in one case. The post‐revision Cobb angle was significantly improved from 29.9° ± 8.3° to 18.7° ± 6.7° (P < 0.001) with a correction rate of 37.5% ± 12.6%. At the final follow‐up, the average Cobb angle was 18.9° ± 6.2° and the correction was well maintained (P = 0.788). The C(7)PL‐CSVL at pre‐revision, post‐revision and at last follow‐up were 23.2 ± 9.3 mm, 14.8 ± 4.8 mm and 14.9 ± 5.4 mm, respectively. Significant improvements (P = 0.004) were observed after revision surgery and there was no evident loss of correction (P = 0.703). There was no significant difference in TK, LL and SVA before and after revision surgery (all P > 0.05). At the last follow‐up, no significant correction loss of above coronal and sagittal parameters were observed (all P > 0.05). The revision methods were individualized according to the primary surgical procedures and the reasons for revision. The recommended revision strategies include incision of pseudarthrosis with sufficient bone graft, fixation of satellite rods, thorough residual HV excision, prolonged fusion to S(2) and transforaminal lumbar interbody fusion at lumbosacral region. Solid bony fusion and no implant‐related complication were detected during the follow‐up. CONCLUSIONS: The causes of revision surgery for patients with congenital scoliosis (CS) due to lumbosacral HV were verified and implant failure with pseudarthrosis was the main reason for failed primary operation.