Progressive Thoracic Idiopathic Scoliosis
The patient is a 15-and-7/12 year-old female with a right thoracic idiopathic scoliosis of 80º. She reports backache when seated for prolonged periods of time, such as the 9-hour car drive for this appointment. She is on the cheerleading squad and complains of some shortness of breath when running. She does not take medication for pain.
Her father and paternal grandmother have scoliosis.
The patient's gait is normal. Thoracolumbar range of motion is full and painless. There is a 15º right thoracic rotational prominence and lumbar region prominence of 5º as measured with the Scoliometer.
Leg lengths are equal. Motor, sensory, and reflex examination of the lower extremities is intact. Negative ankle clonus.
Forced vital capacity (FVC) and forced expiratory volume (FEV) are 74% and 67% of predicted values, respectively for her age and height of 64.75-inches.
Full-length AP (Figure 1A) and lateral (Figure 1B) reveal the above-noted scoliosis. Kyphosis is 17º and sagittal alignment is normal. The patient's spinal MRI was normal.
Figure 1A: AP x-ray
Figure 1B: Lateral x-ray
Figure 2A: Left bending x-ray
Figure 2B: Right bending x-ray
The patient was diagnosed with thoracic idiopathic scoliosis. The sagittal alignment reveals upper thoracic increased kyphosis and apical mid-thoracic loss of kyphosis.
Suggest TreatmentIndicate how you would treat this patient by completing the following brief survey. Your response will be added to our survey results below.
The patient underwent an anterior thoracoscopic (VATS) discectomy with posterior osteotomies followed by posterior pedicle screw instrumented fusion. The surgery was as described below with continuous intraoperative neuromonitoring utilized.
Prone Thoracoscopic Anterior Release
- The patient was placed on the Jackson spinal frame in the prone position. Her right chest and back was prepped and draped to allow lateral thoracoscopic portal placement within the same sterile field and the posterior spinal exposure.
- Three portals were made, the scope introduced, and an evaluation of the chest contents was performed. The pleura was dissected over the T6 through T10 vertebra and the anterior vessels were preserved. Discectomies were performed for purposes of increasing flexibility and achieving fusion from T6-T10.
- Lavage was performed; a chest tube was placed. This portion of the procedure was well-tolerated by the patient. Estimated blood loss was 100 cc, and she received 1.3 liters of lactated Ringer's.
Posterior Instrumentation and Fusion
- A posterior incision was made in the midline through skin and subcutaneous tissue down to the fascia. Bilateral subperiosteal dissection out to the tips of the transverse processes from T2 to L1 was performed.
- Bilateral facetectomies were performed from T2-L1.
- Ponte type osteotomies to the facet joints and laminae were done at T6-T7, T7-T8, T8-T9, T9-T10, T10-T11, and T11-T12. This was done to enhance the correctability of the patient's severe deformity.
- Spinal instrumentation included titanium screws and cobalt chrome rods. Polyaxial screws were placed at T2 and L1 bilaterally and uniplanar screws were utilized in a segmental fashion at other levels. Screw placement was checked with fluoroscopy. Voltage application was done for stimulated EMG to check all screws and satisfactory responses were obtained.
- The first rod (concave side) was cut, contoured, and seated in the screws on the left and set screws were applied. Rod derotation and direct vertebral derotation maneuvers were performed. Provisional tightening was performed. A second rod (convex side) was cut, contoured, and placed in the screws on the right and set screws were applied. Further direct vertebral derotation and compression distraction of the lowest instrumented vertebra was done to horizontalize this vertebra.
- Final tightening of all set screws was performed. Intra-operative x-rays were performed. Further lavage was performed. Decortication of the posterior bony elements was performed. Cancellous allograft combined with Vancomycin and Tobramycin was applied to the decorticated spine.
- A deep drain was placed. The fascia was closed. Further lavage was performed. The subcutaneous tissue was closed and a running subcuticular closure was performed. Sterile dressings were applied.
- She was extubated, moved all extremities, and tolerated the procedures well.
- Estimated blood loss from the posterior portion of the procedure was 1500 cc. She received 4.75 liters of crystalloid and 500 cc of cell saver blood.
Figure 3A: 3 months post-op AP radiograph
Figure 3B: 3 months post-op lateral radiograph
Figure 4: Comparison of pre-op and 3 months post-op AP views
At 1.5 weeks after surgery, the patient was well-balanced in her sagittal plane with a slight shift to her right on the coronal plane. Three small thoracic incisions were well-healed. Motor, sensory, and reflex examination of the lower extremities was intact and gait was normal.
At 3 months after surgery, radiographs (Figures 3A and 3B) revealed maintenance of alignment and correction with implants in good position. The 80º thoracic curvature is stable at 24º. She does not have pain. The patient gained 1.5 inches in height as a result of surgery.
In this patient with right thoracic adolescent idiopathic scoliosis, I do not think there is controversy regarding the indication for surgical treatment. Curves of this magnitude (80 deg) are thought to be universally progressive throughout life and spinal fusion is a successful method of limiting progression.That may be where the controversy ends. There are numerous options for the surgical management of this patient. A case can certainly be made for more traditional methods of instrumentation with hook and/or wire fixation (either with or without an anterior release). In addition there is wide debate over the need/utility of anterior discectomy in such a case especially if segmental pedicle screw instrumentation in utilized. Several authors have written about the increased power of pedicle screws that has obviated the "need" for an anterior procedure in such cases. Having brought up these concerns I would likely have used a very similar approach, with a few noted differences, and will attempt to justify this is the text that follows. Anterior release or not? I judge whether to add an anterior release or not based on several relatively poorly defined and inter-related variable. These include: Cobb angle (>75 deg), thoracic lordosis particularly at the apex (<10 deg), rotational deformity (angle of trunk rotation >20 deg), and skeletal immaturity (open triradiate cartilage). In some ill defined manner, I factor each of these variables into the equation that includes the desires of the patient for high degrees of 3 dimensional correction, their interest in limiting surgical exposure, pulmonary function, etc. My primary goal in most cases of disc excision is to gain the ability to shorten the anterior column. Allowing the disc spaces to collapse, makes the correction of kyphosis and transverse plane derotation substantially easier. If one has the expertise to perform disc excision via minimally invasive thoracoscopic methods, than the reduced morbidity compared to an open approach also should factor into the risk-benefit analysis and thus the decision making.
Posterior Osteotomies? Depending on your definition of an osteotomy, I think this should become routine for most cases of thoracic AIS and certainly for a case of this curve magnitude. The "osteotomy" I use in this situation is the type described by Alberto Ponte, although he described it for the treatment of hyperkyphosis, rather than relative lordosis found in scoliosis. In addition to the standard inferior articular facet excision, the "Ponte" involves excision of the interspinous ligament, ligamentum flavum and most importantly the superior articular facet. This results in a complete sectioning of the soft tissue connections between the vertebrae posteriorly.
Intraoperative Traction? It was not mentioned in this case, however, I am a proponent of intraoperative tong-boot traction and find it helpful in curves beginning at about 75 degrees. This required reliable intaoperative neuromonitoring especially of the motor tracts.
Implant Choice: I favor the use of the "strongest" rod material available if maximizing 3 D correction is the goal. For this particular curve pattern, I believe there is little risk of imbalance with maximal correction, and as such I would suggest a stronger rod. Today for any given rod diameter (I favor 5.5 mm as used here), work hardened steel rods are that material. Cobalt chromium rods offer slightly greater stiffness compared to steel, however, depending on how the rods are contoured, rod yield strength becomes the variable that determines the ultimate corrective force that is delivered to the spine.
In summary, there are a variety of viable and reasonable surgical approaches for this patient. The primary goal remains prevention of progression with the secondary goal of achieving a "balanced" correction in all 3 planes, hoping to minimize the clinical deformity and functional loss. The selection of fusion levels is a controversy that I have avoided in this discussion, but certainly has a large impact in the outcome.