How common is acute pelvic fixation failure after adult spine surgery? A single-center study of 358 patients

Abstract

OBJECTIVE There is a paucity of literature on pelvic fixation failure after adult spine surgery in the early postoperative period. The purpose of this study was to determine the incidence of acute pelvic fixation failure in a large single-center study and to describe the lessons learned. METHODS The authors performed a retrospective review of adult (≥ 18 years old) patients who underwent spinal fusion with pelvic fixation (iliac, S2-alar-iliac [S2AI] screws) at a single academic medical center between 2015 and 2020. All patients had a minimum of 3 instrumented levels. The minimum follow-up was 6 months after the index spine surgery. Patients with prior pelvic fixation were excluded. Acute pelvic fixation failure was defined as revision of the pelvic screws within 6 months of the primary surgery. Patient demographics and operative, radiographic, and rod/screw parameters were collected. All rods were cobalt-chrome. All iliac and S2AI screws were closed-headed screws. RESULTS In 358 patients, the mean age was 59.5 ± 13.6 years, and 64.0% (n = 229) were female. The mean number of instrumented levels was 11.5 ± 5.5, and 79.1% (n = 283) had ≥ 6 levels fused. Three-column osteotomies were performed in 14.2% (n = 51) of patients, and 74.6% (n = 267) had an L5–S1 interbody fusion. The mean diameter/length of pelvic screws was 8.5/86.6 mm. The mean number of pelvic screws was 2.2 ± 0.5, the mean rod diameter was 6.0 ± 0 mm, and 78.5% (n = 281) had > 2 rods crossing the lumbopelvic junction. Accessory rods extended to S1 (32.7%, n = 117) or S2/ilium (45.8%, n = 164). Acute pelvic fixation failure occurred in 1 patient (0.3%); this individual had a broken S2AI screw near the head-neck junction. This 76-year-old woman with degenerative lumbar scoliosis and chronic lumbosacral zone 1 fracture nonunion had undergone posterior instrumented fusion from T10 to pelvis with bilateral S2AI screws (8.5 × 90 mm); i.e., transforaminal lumbar interbody fusion L4–S1. The patient had persistent left buttock pain postoperatively, with radiographically confirmed breakage of the left S2AI screw 68 days after surgery. Revision included instrumentation removal at L2–pelvis and a total of 4 pelvic screws. CONCLUSIONS The acute pelvic fixation failure rate was exceedingly low in adult spine surgery. This rate may be the result of multiple factors including the preference for multirod (> 2), closed-headed pelvic screw constructs in which large-diameter long screws are used. Increasing the number of rods and screws at the lumbopelvic junction may be important factors to consider, especially for patients with high risk for nonunion.

Biomechanical evaluation of multiple pelvic screws and multirod construct for the augmentation of lumbosacral junction in long spinal fusion surgery

“…Although SPF indeed reinforces the construct stiffness, 12.0%–46.9% of implant failure rate has been reported by previous studies ( Park et al, 2021b ; Gao et al, 2021 ). To reduce the incidence of mechanical complications, multiple pelvic screws or multirod construct have been applied as an advanced SPF technique ( Uotani et al, 2021 ; Lee et al, 2022a ; Lee et al, 2022b ; Tang et al, 2022 ). The current study revealed that both multiple pelvic screws and multirod construct could increase the mechanical stability of LSJ, reduce strain on the lumbosacral rod, and protect the S1-PS and sacrum.…”

“…In addition to pseudarthrosis, postoperative residual sagittal and/or coronal malalignment are risk factors for implant failure following long spinal fusion for ASD ( Lee et al, 2022b ; Martin et al, 2022 ). For complex cases with preoperative several sagittal and coronal malalignment, three-column osteotomy (3-CO) and sequential correction techniques are usually needed ( Lau et al, 2021 ; Shi et al, 2021 ).…”

“…Substantial rates ranging from 23.7% to 56.0% have been reported by previous cohort studies (Guler et al, 2015;Hallager et al, 2017;Eastlack et al, 2022). Among the implant failure, rod fracture (RF) was the most common complication, and 28.0%-81.3% of RF occurred at lumbosacral rods (Devlin et al, 1991;Lertudomphonwanit et al, 2018;Rabinovich et al, 2021). The culprits of RF were pseudarthrosis and the increasing fatigue cracks under external stress (Yamanaka et al, 2015;Sardi et al, 2022).…”

“…Although the application of SPF, the incidence of implant failure is still unsatisfactory, with reported rates ranging from 12.0% to 46.9% ( Park et al, 2021b ; Gao et al, 2021 ). In recent cohort studies, advanced SPF technique by multiple pelvic screws or multirod construct has been recommended following long spinal fusion to stabilize the LSJ further, protect the primary rod and screws, and reduce the persistent motion of SIJ ( Uotani et al, 2021 ; Lee et al, 2022a ; Lee et al, 2022b ). However, there was only one small-size cohort study reporting the application of combining the multiple pelvic screws and multirod construct, without any control groups ( Shen et al, 2018 ).…”