Smiley Face Shaped Rod Technique Versus Instrumented Posteriolateral Fusion in Treatment of Isthmic Lumbar Spondylolisthesis

Isthmic spondylolisthesis is considered to represent a fatigue fracture of the pars interarticularis of the neural arch, The clinical symptom is activity-related back pain in young and athletic patients . The cause of Isthmic spondylolisthesis in these patients is repetitive stress of the pars interarticularis with subsequent microfracture, which in turn may lead to a bony defect and cause progressive spondylolisthesis in up to 25% of cases. Surgical intervention is indicated for patients who are not responsive despite adequate period of conservative management such as activity modification , physical therapy, and occasionally bracing .

Techniques for repair of a pars defect include Scott wiring , a Buck screw , a pedicle screw and hook , multiple segment fixations or a U-rod . After repair, radiographic healing rates range from 67 percent to 90 percent; asymptomatic and return to sports rates range from 80 percent to 90 percent.

These methods have achieved variable success .In Buck screw fusion surgery,it is not effect on flexion and axial rotation of the spine but bone healing is compromised.

Stabilization with wiring and titanium cable had less success rate than other methods and requires the use of lumbar brace or prolonged immobilization.

The pedicle screw-vertebral plate hook system may complicated by injury to the dural sac or nerves ensues.