Faculty Bibliography

PURPOSE: Our aim was to revise the different strategies for treating an infected disc arthroplasty. METHODS: Despite recognition that disc replacement may reduce the incidence of adjacent-segment disease, the risk of potential complications associated with primary and revision total disc arthroplasty has diminished surgeon enthusiasm for the procedure. We performed a literature review of the different revision strategies for an infected disc arthroplasty. RESULTS: The need for revision of lumbar total disc arthroplasty has been reported in a number of prospective, randomised trials (level I or II evidence). Suboptimal patient selection and/or surgical technique accounted for the majority of failed disc arthroplasties. Revision procedures include posterior stabilisation or anterior extraction and conversion to arthrodesis. The risk of injury to the great vessels and retroperitoneal structures is greater during revision than primary procedures. The use of a distant lateral, or transpsoas, approach to the anterior column may reduce these adverse events. Also, the use of adhesion barriers has been shown to reduce adhesions in abdominal and pelvic surgery and may be of benefit in revision disc arthroplasty. CONCLUSION: This review article provides an update on the various treatments for infected lumbar disc prosthesis and the different surgical approaches used in these difficult cases. It also describes potential options to avoid complications associated with the revision surgical approach.

INTRODUCTION: Postoperative spondylodiscitis is a primary infection of the nucleus pulposus with secondary involvement of the cartilaginous endplate and vertebral bone. Although uncommon, postoperative spondylodiscitis causes major morbidity and may be associated with serious long-term sequelae. Several risk factors had been identified, including immunosuppression, obesity, alcohol, smoking, diabetes and malnutrition. MATERIALS AND METHODS: A review of the literature was done to analyse the diagnosis, treatment and prevention of postoperative spondylodiscitis. RESULTS: We found that the principles of conservative treatment are to establish an accurate microbiological diagnosis, treat with appropriate antibiotics, immobilise the spine, and closely monitor for spinal instability and neurological deterioration. The purpose of surgical treatment is to obtain multiple cultures of bone and soft tissue, perform a thorough debridement of infected tissue, decompress neural structures, and reconstruct the unstable spinal column with bone graft with or without concomitant instrumentation. CONCLUSIONS: Appropriate management requires aggressive medical treatment and, at times, surgical intervention. If recognised early and treated appropriately, a full recovery can often be expected. Therefore, clinicians should be aware of the clinical presentation of such infections to improve patient outcome. A review of the literature was done to advance our understanding of the diagnosis, treatment, prevention and outcome of these infections.

STUDY DESIGN: This study retrospectively compares the clinical and radiologic outcomes of unilateral transforaminal lumbar interbody fusion (TLIF) with those of transvertebral screw fixation of the lumbosacral spine in high-grade spondylolisthesis. OBJECTIVE: To examine the outcome and perioperative complications of unilateral TLIF and compare those results with Transvertebral Screw Fixation in the treatment of high-grade spondylolisthesis. SUMMARY OF BACKGROUND DATA: High-grade spondylolisthesis has been associated with a high complication and failure rate regardless of the method of treatment. We compare 2 techniques to improve success rates. METHODS: Forty patients were divided into 2 groups: group A, unilateral TLIF, and group B, transacral screws. The mean age was 33 years (range, 19-48 years), and the mean follow-up was 35 months (range, 24-48 months). The mean grade of spondylolisthesis measured by Meyerding grading was 3.6 (range, 3-5). A Scoliosis Research Society outcome score was obtained on all patients. Fusion was determined by both radiograph and computed tomography scan. RESULTS: Group A: 100% fusion. The slip angle improved from 38.6 degrees (range, 24-78 degrees ) before surgery to 23.8 degrees (range, 12-38 degrees ) after surgery. Group B: 95% of patients evidenced solid fusion by the 6-month follow-up. The slip angle, improved from 38.2 degrees (range, 22-78 degrees ) before surgery to 23 degrees (range, 9-36 degrees ) after surgery. There was no significant improvement in the percentage slip or the sacral inclination in any of the groups. Complications: A: 7 unintended durotomies and 3 wound infections. B: 1 unintended durotomy, 1 pseudarthrosis, 2 wound infections, and 1 implant failure. There were no neurologic complications in any of the groups. The Scoliosis Research Society outcome instrument demonstrated good postoperative pain control, function, self-image, and satisfaction in both groups. CONCLUSION: No significant differences in radiologic and clinical outcome were found, in either group. Both procedures appear to be safe and effective surgically and radiographically

STUDY DESIGN: Prospective multicentric study. OBJECTIVE: To present the preliminary results of an innovative method for standardized correction of scoliosis, vertebral coplanar alignment (VCA), based on a novel concept: the relocation of vertebral axis in a single plane. SUMMARY OF BACKGROUND DATA: Normal standing spine has no rotation in coronal or transverse planes, therefore X and Z axis of vertebrae are in the same plane: they are coplanar. VCA intends to relocate these axis in one plane, correcting rotation and translation, while X axis are returned to its normal posterior divergence in sagittal plane in thoracic spine. METHODS: Twenty-five consecutive adolescent idiopathic scoliosis patients (Lenke type 1) underwent posterior surgery with segmental pedicle screw fixation. Slotted tubes were attached to convex side screws. Two longitudinal rods were inserted through the end of tubes. Then, they were separated along the slots, driving the tubes into one plane, making the axis of the vertebrae coplanar and thus correcting transverse rotation and coronal translation. To obtain kyphosis, distal ends of the tubes were spread in thoracic spine. Correction was maintained by locking a definitive rod in the concave side, then tubes were retrieved and the convex side rod, inserted and tightened. Correction was assessed on preoperative and postoperative full-spine standing radiograph. Vertebral rotation was measured on computed tomography-scan and magnetic resonance imaging. RESULTS: Preoperative average thoracic curves of 61 degrees were corrected to 16 degrees (73%). Preoperative average thoracolumbar curves of 39 degrees were corrected to 12 degrees (70%). Preoperative average thoracic apical rotation of 24 degrees was corrected to 11 degrees (56%). Preoperative average thoracic kyphosis of 18 degrees remained unchanged after surgery; however, no patients had kyphosis <10 degrees after surgery. Rib hump improved from 30 to 11 mm (65%). There were no perioperative complications. CONCLUSION: VCA provided excellent correction of coronal and transverse planes with normalization of thoracic kyphosis in Lenke type 1 adolescent idiopathic scoliosis surgery

STUDY DESIGN: A prospective clinical study of high thoracic pedicle screws monitored with triggered electromyographic (EMG) testing. OBJECTIVE: To evaluate the sensitivity of recording intercostal muscle potentials to assess upper thoracic screw placement. SUMMARY OF BACKGROUND DATA: Triggered EMG testing from rectus muscle recordings, which are innervated from T6 to T12, has identified medially placed thoracic pedicle screws. No clinical study has correlated an identical technique with the intercostal muscle for upper pedicle screws placed in the upper thoracic spine (T3-T6). METHODS: A total of 311 high thoracic screws were placed in 50 consecutive patients. Screws were placed from T3 to T6 and were evaluated using an ascending method of stimulation until a compound muscle action potential was obtained from the intercostal muscles. Screw position was then evaluated using computed tomography and results were compared with evoked EMG threshold values. RESULTS: Fifteen screws (5%) showed penetration on postoperative computed tomography scans. Eleven screws showed medial cortical breakthrough (3.6%), 6 had stimulation thresholds <or=6 mA, and 5 had stimulation thresholds between 6 and 10 mA. Stimulation values for all breached screws decreases 60% to 65% from their mean. Four screws (1.3%) showed lateral cortical breakthrough with stimulation thresholds >20 mA. Of the 296 screws with thresholds between 6 and 20 mA, 285 (91%) were within the vertebra. No postoperative neurologic complications were noted in any of the 50 patients. CONCLUSION: In this series, cortical violation is highly unlikely in patients whose stimulation threshold lies between 6 and 20 mA with values 60% to 65% decreased from the mean (98% negative predictive value). Although verification of screw placement should not depend solely on stimulation thresholds, pedicle screw stimulation provides rapid and useful intraoperative information on screw placement during procedures involving the use of thoracic pedicle screws

We describe a 61 year-old caucasian male diagnosed with rheumatoid arthritis. He was started on methylprednisolone pulses because of a severe flare of symmetric polyarthritis while he was on weekly intramuscular methotrexate and low-dose oral prednisone. After the second pulse of methylprednisolone the patient suddenly developed severe abdominal pain with free air under the right hemidiaphragm in the chest roentgenogram. The emergency surgery revealed the perforation of a colonic diverticulum. We suggest that methylprednisolone pulses should be carefully used in those patients over 50 years of age and/or people with demonstrated or suspected diverticular disease