Lumbopelvic(spinopelvic) fixation for sacral nonunion

 Sacral fracture - Denis classification

Sacral fracture

Denis zone I

50% of fractures

Neurologic deficit : 5.9%

L5 nerve root


Denis zone II

34.3% of fractures

Neurologic deficit : 28.4%

Varying effect on L5-S2


Denis zone III 

15.7% of fractures

Neurologic deficit : 56.7%

Affects bower, bladder, L5-S2


Actual incidence of neurologic deficit was 3.5%, lower than 21.6% by Denis et al.



Definition – Delayed union and Nonunion

Delayed union

fracture has not healed in the time frame that would be expected

Generally between 3 and 6 months

time frame for healing varies for different parts of body

thought of as a precursor to nonunion


Nonunion

minimum 9 months after injury + shows no visible progress for 3 months

FDA definition

A fracture that, in the opinion of the treating physician, has no possibility of healing without further intervention

waiting 9 months may result:

 prolonged morbidity, inability to return to work, narcotic dependence, and emotional impairment

Nonunion

Nonunions are classified based on: location, infection, and etiology


Epiphyseal, metaphyseal, or diaphyseal

Septic or aseptic

Hypertrophic, oligotrophic, or atrophic

Pseudoarthrosis

Nonunion

Hypertrophic nonunion (Hypervascular)

Adequate vascularity, Abundant Callus, Lack of stability

Capable of biologic reaction (Fibrocartilage formation)

Elephant foot nonunion, Horse hoof nonunion

→ Maximizing mechanical stability


Oligotrophic nonunion

Adequate vascularity, Little or no callus

excess motion & impaired biological potential

→  increase both biologic and mechanical environment



Nonunion

Atrophic nonunion (Avascular)

Lack of vascularity, No callus

Incapable of biologic reaction

→ debridement, decortication and bone grafting, BMP


Nonunion of pelvis

Classified into three main groups:

anteroposterior compression, lateral compression, and vertical shear 


Signs and symptoms

pain, limp, instability, and clinical deformity


Tendency on fracture part

Sacroiliac area - avascular type

Ramus - hypervascular type


Insufficient immobilization thought to be the cause

fragments were not adequately reduced or sufficiently


Lumbopelvic fixation

Current indications

long arthrodesis constructs

high-grade spondylolisthesis

unstable sacral fractures

pelvic obliquity with associated lumbar deformity

in children with neuromuscular deformity


Lumbopelvic fixation

Goals of Lumbopelvic fixation

Stabilization of the spinopelvic junction

allow early weight bearing

particularly in patients with multiple injuries


Complications

screw pullout, breakage leads to removal

Lower risk on S2AI screw fixation


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