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HALO-SPINE-PELVIC EXTERNAL FIXATION OF SEVERE INFECTED PSEUDOARTHROSIS OF THE SPINE

Author: Dr. Mikhail Samchukov
Co - authors: Dr. Karl Rathjen, Dr. Alex Cherkashin, Dr. John Birch
Country: USA
E-mail: mike@globalmednet.com

Mikhail Samchukov, Karl Rathjen, Alex Cherkashin, John Birch
Texas Scottish Rite Hospital for Children, Dallas , Texas , USA

Introduction. Infected spinal pseudoarthrosis is a significant challenge for orthopedic surgeons. External skeletal fixation has an established role in the treatment of infected pseudoarthrosis of long bones. Use of external fixation in the treatment of infected pseudoarthrosis of the spine was originally described by Shufflebarger and Dubbousset 1 and has subsequently been occasionally reported in the literature 2-3 . The purpose of this study is to describe the use of a halo-spine-pelvic external fixation in the management of infected circumferential (anterior and posterior) pseudoarthrosis of the spine.

Materials & Methods. The patient is a 14-year-old boy with a thoracic-level myelomeningocele. At 10 years of age he had an anterior and posterior spinal fusion with Dunn McCarthy rod instrumentation for treatment of a 90° scoliosis. His postoperative course was uneventful until he was presented 4 years postoperatively with a 2-week history of fatigue, fever and back pain. Inflammation and fluctuance of the spinal wound was evident on examination. At surgery, a liter of purulent fluid was found engulfing the entire spine and extending into the retroperitoneal space through a lumbar pseudoarthrosis. The posterior spinal instrumentation was removed through the original incision (Fig. 1) and the retroperitoneal space drained through an anterior approach during multiple irrigations and debridements performed over several weeks.

Cultures grew MRSA, Interococus Fecalis and Pseudomonas, for which he received parenteral antibiotics (Vancomycin, Flagyl, and Ciprofloxacin). Radiographic evaluation showed pseudoarthroses at L1/L2 and at L4/L5 junctions (Fig. 2). It was felt that the gross motion present through the L4/L5 circumferential pseudoarthrosis would likely prevent soft tissue healing. Subsequently, a decision was made to stabilize the patient in a circular type halo-spine-pelvic external fixator.

Initially, a halo ring was applied with 4 pins. This was followed by the placement of 2 anterior-to-posterior half pins and 2 posterior-to-anterior cross stopper-wires through the iliac wing as well as 1 coronal plane wire through the sacrum. The pelvic wires were tensioned and attached to the custom modified pelvic ring, which was connected to 2 small arches previously attached to the anterior half pins. Eight 5-mm diameter half pins were then placed through pedicles at L4, L3, and 3 more levels proximally. These half pins were attached to 4 arches interconnected by threaded rods. Using the external fixator, the translational deformity at the L4/L5 pseudoarthrosis was reduced and the spine was compressed between the L1/L2 and L4/L5 junctions creating lordosis via universal lockable hinges. Finally, the interconnected arches were attached to the halo ring proximally and pelvic support distally creating a stable halo-spine-pelvic external frame (Fig. 3).

Results

The patient's soft tissue wounds were managed with a VAC wound closure system and healed in 3 months at which time the external fixator was removed. At follow-up evaluation, the patient was doing well, taking an oral diet and having returned to normal wheel chair activities and school. His back has completely healed and spine deformity has significantly improved (Fig. 4).