Instrumentation Failure After Posterior Vertebral Column Resection in Adult Spinal Deformity

Retrospective study of instrumentation failure after posterior vertebral column resection (pVCR) in adult spinal deformity (ASD) patients.The morbidity and related risk factors of the instrumentation failure.Instrumentation failure is another common complication after pVCR. But no report about it has been published before. The safety of titanium mesh cages (TMCs) for this failure is still unknown so far.A total of 35 consecutive ASD patients (18 females and 17 males), who underwent pVCR between May 2005 and December 2014 in our hospital, were retrospectively reviewed. The mean age and follow-up period were 37.8 ± 12.8 years and 45.5 ± 27.3 months. Proportion was used to describe the morbidity of instrumentation failure. Potential risk factors were compared between patients with and without instrumentation failures by using Student t test or χ tests (Fisher exact tests). Risk factors related to TMCs were analyzed in TMC group.There were 70 vertebra resected in total, with the mean of 10.3 segments instrumented. The mean correction rates of main curve (n = 25) and segmental kyphosis (n = 35) were 68.8% and 67.9%, respectively. Five patients (14.3%) suffered rod breakage. The failure was noted an average of 6.8 months after surgery. The risk factors included BMI (>27, P = 0.026), comorbidity (Achondroplasia, P = 0.047), and anterior column defect (ACD>20 mm, P = 0.045). TMC subsidence of ≥5 mm was the risk factor related to TMC in TMC group (P = 0.041).It is safe to reconstruct with a TMC after pVCR in ASD, but the height should be as low as possible to reduce ACD. For those patients with risk factors, autologous bone graft and a satellite rod should be considered. If TMC subsidence ≥5 mm, a frequent follow-up should be performed.4.