We removed 23 Charité artificial discs in 19 patients due to severe back-and legpain and performed an anterior as well posterior fusion. Mean interval between insertion and retrieval is 8,4 years (3,0–16,0 years). The mean age at retrieval is 49,4 years (40–72 years). The cause of persistent or recurrent pain was one or more of several problems thought to be related to the pain: subsidence, migration, wear with or without breakage of the metal marker ring, facetjoint or adjacent degeneration. In all cases wear of the polyethylene core was seen in major or minor degree. The wear was related to posterior impingement possibly due to hyperlordosis and extension instability and was subsequently more pronounced in the peripheral rim than in the central dome. Also a relationship was noted to in vivo oxidation of the polyethylene, especially in the rim. In the periprosthetic tissue an inflammatory reaction was found, more in the severe wear cases. Polyethylene loaded macrophages were seen, also polyethylene particles lying freely in the tissue. The macrophages proved positive for Interleukin 6. The wear pattern and the inflammatory reaction resembles the pattern seen in total hips and knees. Probably a substantial number of patients will exhibit these wear changes some years after insertion. It is questionable whether changes in sterilization and packaging and better insertion and sizing techniques will prevent wear development in the future.

Introduction: In this study we focus on idiopathic scoliosis with a primary thoracic curve and a secondary lumbar curve. We were interested in how the lumbar curve corrects following selective thoracic fusion and whether one can predict the correction of the lumbar curve. In the literature it is said that the lumbar curve spontaneously corrects to balance the thoracic curve after selective thoracic fusion. Because of these findings we postulate there should be a correlation between the correction of the lumbar and thoracic curve of the scoliosis.

Recently we showed in patients treated with Harrington instrumentation with sublaminar wiring (second generation technique) that the correction of the lumbar curve was not a reflection of the thoracic correction. So it is interesting to know whether with the use of third generation instrumentation techniques and more sophisticated classification systems the correlation of the unfused lumbar cure becomes more predictable.

Objective: To establish whether in primary thoracic idiopathic scoliosis treated with selective thoracic fusion using CD instrumentation there is a significant correlation (p< 0.05) between the correction of the thoracic and lumbar curve. And to assess whether, in the in the individual patient, the lumbar modifier (A, B and C) according Lenke, can be used as a correct predictor of outcome results. The higher the correlation coefficient between the relative (%) corrections of the thoracic and lumbar curves, the higher the predictability of the correction of the unfused lumbar curve.

Material and methods: We performed a retrospective study on 38 patients with adolescent idiopathic scoliosis treated by selective thoracic fusion (CD instrumentation). There were 29 female and nine male patients. For radiographic evaluation we used the standing antero-posterior and lateral projections of the thoracic and lumbar spine, preoperatively and at least one year postoperative. We assessed the frontal and sagittal Cobb angles. The angles were all measured by the same investigator (second author).

Results: Using Pearson correlation analyses we found a significant correlation (p< 0.001) between the relative (%) corrections of thoracic and lumbar curves (table1). The correlation coefficient between the relative correction of the thoracic and lumbar curve decreased with the Lumbar modifier (A, B, C).

Conclusion: A significant correlation is present between the relative corrections of the main thoracic curve and the lumbar curve after selective thoracic fusion in idiopathic scoliosis. The recently introduced new classification system seems to be of great predictable value for the spontaneous correction of the lumbar curve. Depending on the curve-type, a different technique for predicting the outcome should be used.

Study design: A retrospective evaluation of screw position after double rod anterior spinal fusion in idiopathic scoliosis using computerised tomography (CT).

Objective: To evaluate screw position and complications related to screw position after double rod anterior instrumentation in idiopathic scoliosis.

Summary of Background Data: Anterior instrumentation and fusion in idiopathic scoliosis is gaining widespread use. However, no studies have been published regarding the accuracy of screw placement and screw related complications in double rod and double screw anterior spinal fusion and instrumentation in idiopathic thoracolumbar scoliosis surgery.

Methods: CT examinations were performed after anterior spinal fusion and instrumentation in 17 patients with idiopathic scoliosis. The vertebral rotation at each level was measured. At each instrumented level the position of the screw and the plate relative to the spinal canal, relative to the neural foramen and relative to the aorta was measured. Complications related to screw position were registered.

Results: 189 screws in 17 patients were evaluated. The average age of the patients was 31 years (range 15–53 years). Fourteen patients had a left convex thoracolumbar curve and three patients a right convex thoracolumbar curve. The mean lumbar apical rotation preoperatively was 27°. Malposition occurred in 23% of the total number of screws. Three screws were in the spinal canal (1%). This resulted in pain in the right leg. However, electromyography showed no abnormalities. On three levels there was contact between the instrumentation and the aorta. No vascular complications did occur. 113 screws (ten patients) were placed under fluoroscopic guidance and 76 screws (seven patients) were placed without use of fluoroscopy. No complications related to screw position were observed in the group in which the screws were placed under fluoroscopic guidance.

Conclusions: Adequate placement of two screws in the vertebra in idiopathic scoliosis is a technically demanding procedure, which results in frequent malposition, fortunately with a low risk of neurological and vascular complications.

Study design: Prospective study after minimally invasive anterior approach of the thoracolumbar spine in scoliosis correction.

Objective: To describe the technique and first results after minimally invasive anterior approach of the thoracolumbar junction with insertion of double rod and double screw instrumentation.

Summary of Background Data: Minimally invasive techniques are used at many areas of surgery nowadays. Minimally invasive surgery should have the same correction potential as with conventional approaches. Possible advantages of minimally invasive surgery are small incisions, less tissue damage, less morbidity and an improved cosmetic appearance.

Methods: In this study we describe the technique and the preliminary results of minimally invasive open approach of the thoracolumbar spine with insertion of double rod and double screw instrumentation. A consecutive series of seven patients were included. All patients were female with a mean age of 16.7 years (range 10–28). The cause of thoracolumbar scoliosis was mixed.

Results: The thoracolumbar curve was 59° preoperatively and 22° at six months follow up (63% correction). The unfused thoracic curve was 40° preoperatively and 29° at six months follow-up. In the sagittal plane of the fused levels Cobb angle was 61° of lordosis preoperatively and 35° of lordosis at six months follow up. Lumbar lordosis of the unfused spine was 16° preoperative and 5° at six months follow up. Thoracic kyphosis was 33° preoperatively and 24° at six months follow-up. The average time of surgery was 6.6 hours (range 5.5–7hours). The average estimated blood loss was 764ml (range 350–1200ml). Average hospital stay was 11 days (range 5–14days), and average stay at the intensive care unit was 1.7 days (range 0–3 days). One minor neurological complication with complete recovery was observed.

Conclusions: Minimally invasive surgery has the advantage of less tissue damage, less morbidity and a better cosmetic appearance. With newer implants a good correction of the scoliosis can be achieved.