Modified Scott Wire Technique

Kim W. Hammerberg and James M. Osborn

Goals of Surgical Treatment

To unite the pars defect and maintain the lumbar motion segment function.

Diagnosis

Repetitive stress spondylolysis is demonstrated by anteroposterior (AP), lateral, and oblique radiographs of the lumbar spine. Bone scans can be helpful in differentiating an acute lysis from a chronic lysis with pseudarthrosis. Computed tomography (CT) scans or magnetic resonance imaging (MRI) can also be helpful in detecting a lysis as well as determining its chronicity.

Indications for Surgery

1. Refractory back pain

2. Normal disc morphology on MRI

3. Low-grade slip (< 5 mm)

4. Less than 30 years of age

Contraindications

1. Significant disc degeneration

2. Radicular symptoms requiring decompression

3. Slips > 5mm

4. High-demand patients

5. Significant dysplasia in the posterior elements

6. Other mitigating factors (e.g., rheumatoid arthritis, chemotherapy)

Advantages of This Technique for Direct Repair of Spondylolytic Defect

1. Preservation of motion segment with less distortion of normal spinal mechanics.

2. Shorter operative time.

3. Less average blood loss.

4. Low-profile, inexpensive instrumentation.

5. Hardware can be retained.

6. Does not interfere with posterior segmental fusion if a salvage procedure is required.

Disadvantage

Pseudarthrosis rate of between 4 and 37%.

Procedure

The basic principles of pseudarthrosis surgery apply: meticulous debridement, autogenous bone graft, and compression across the fracture site.

Positioning and Incision