Growing rod procedure

The growing rod is a surgical technique developed as an alternative procedure to spinal fusion to treat early-onset scoliosis (EOS), although the latter is the final and definitive treatment for scoliosis.

The growing rod can be considered a delaying tactic to spinal fusion and is a distraction-based method favorable to growth and development, especially ribcage.

Indications

The fundamentals of the treatment are to correct the deformity and allowing thoracic growth for optimal cardiopulmonary function and delay any surgical intervention for as long as possible.

Growing rod surgery is indicated when scoliosis progresses to more than 50°, and conservative management has failed.

ProceduresProcedure

The growing rod consists of proximal and distal anchors of pedicle screws or hooks attached to the spine and single or double vertical rods attached to the anchors. 

The distal and proximal rods are connected by a telescopic unit that allows distraction or lengthening, typically done at 6-month intervals through surgical exposure.

The traditional surgical technique for applying the growing rod involves a posterior midline incision. Submuscular dissection is performed along the incision. Proximal and distal anchor placement requires subperiosteal exposure.

Hooks or pedicle screws may be used for instrumentation. Pedicle screw constructions are mechanically more stable than hooks. Pedicle screws can be placed in young children because they do not affect the growth of the pedicle or spinal canal.

The lengthening procedure is performed every six months by distracting the rods through the connector. This procedure is an outpatient procedure and involves a small incision above the connector. In addition to growth preservation, common distraction every six months accelerates the growth of individual vertebral bodies within instrumentation levels.

On the other hand, the spine becomes stiffer overtime during the treatment of growing rods. Thus, repeated distraction requires more force in most patients but achieves less length; hence, the term "diminishing returns rule" emerged to describe this phenomenon.

When the patient reaches skeletal maturity, definitive fusion surgery is indicated.

Follow-up

Monitoring scoliosis and the integrity of the growing rods is done with radiographs of the spine in anteroposterior and lateral projections. Some authors suggest supplementing with flexion and extension projections.

Complications

Growing rod surgery is associated with a high risk of complications.

First, the exemplary fusion operation following treatment with growing rods is a demanding procedure due to the self-fusion and involves a spinal osteotomy in the vast majority of cases. In this regard, there is an ongoing debate on whether a spinal fusion should be performed in those patients who have completed treatment with growing rods and have reached skeletal maturity with good spinal alignment.

Among the complications closely associated with the procedure of using growing rods are:

• rod fracture
• proximal junctional kyphosis (PJK)
• the need for repetitive anesthesia
• deep surgical site infection
• failure of proximal fixation