Bilateral vascularized rib grafts to promote spinopelvic fixation in patients with sacral agenesis and spinopelvic dissociation: a new surgical technique

Abstract

Background context: Sacral agenesis is a rare congenital disorder that may have spinopelvic instability due to sacroiliac joint malformation. Surgical indication in patients with sacral agenesis is to improve their sitting balance and protect the visceral organs. Achieving solid arthrodesis across this congenital malformation is challenging and prone to non-union.

Purpose: The purpose of this study was to describe a novel surgical technique with vascularized ribs for management of sacral agenesis and complex spinopelvic dissociation.

Study design: Retrospective study.

Patient sample: Six patients with sacral agenesis were reviewed and followed for a mean of 8.5 years after spinopelvic fusion augmented with vascularized rib graft spanning the lumbo-pelvic junction.

Outcome measures: The primary outcome measure was the presence or absence of a stable spinopelvic junction and fusion across the spine-vascular rib grafts-pelvis interface. The secondary outcome measures were maintenance of pelvic obliquity, lumbosacral kyphosis, and overall sagittal balance.

Methods: The surgical procedure consisted of two-stage surgeries performed 6-12 weeks apart. The first stage consisted of spinal instrumentation and correction of the deformity via a posterior approach and impaction of one of the vascularized ribs from the spine to the iliac crest. The second stage consisted of an anterior thoraco-lumbar approach for spinal fusion and the second vascularized rib spanning the spine to the iliac crest.

Results: All six patients eventually achieved a solid spinal and spinopelvic fusion. All vascularized ribs increased in diameter over time. A high complication rate consisted mainly of spinal infections and prominent hardware requiring revision surgeries (a total of seven procedures in four patients). Two patients had decreased mobility secondary to spinopelvic surgery at last follow-up.

Conclusions: Spinopelvic fusion can be successfully achieved with this novel surgical technique using vascularized rib grafts. This technique allows for biological long-term maintenance of the sagittal deformity correction. Fusion across the lumbosacral junction in patients with sacral agenesis may place them at risk of losing the ability to mobilize independently. Recent lower profile implants have prevented implant-related complications.

Keywords: Congenital scoliosis; Lumbosacral kyphosis; Pedicle screws; Sacral agenesis; Spinopelvic fusion; Vascularized rib graft.