Hemivertebral deformity is a defect in vertebral body formation that causes approximately 46% of congenital scoliosis. Since the upper and lower growth plates of fully segmented hemivertebrae are intact, most hemivertebral deformities, except for bilaterally symmetrical hemivertebrae, are characterized by progressive worsening of the deformity, averaging about 4° per year (1° to 33°). Therefore, early surgery is the only effective treatment for this type of deformity. Anterior and posterior one-stage hemivertebrectomy was carried out in our department from August 2000, and the results of its initial treatment have been reported, and the results of the 2-year and more than 2-year follow-up are summarized here.
1. Clinical data.
A total of 25 cases of this type of surgery were completed by the corresponding authors, and all 20 patients were followed up for more than 2 years, except for 5 cases due to loss of follow-up or follow-up time less than 2 years. Among them, 10 cases were male and 10 cases were female; age ranged from 5 to 16 years old, with a mean of 11.7 years. All patients had preoperative full frontal and lateral spine radiographs in the standing position, left and right Bending position, and posterior convex Fulcrum position, CT three-dimensional reconstruction, myelography or MRI to clarify the diagnosis, determine the position of the hemivertebral body and its relationship with the adjacent vertebrae, and exclude concomitant spinal cord abnormalities. Left and right Bending x-rays are used to evaluate compensatory bending flexibility and to determine the extent of fusion. The position of the hemivertebral body and the associated deformity.
2.Treatment methods.
(a) Surgical method: general anesthesia with tracheal intubation, and the patient is first placed in the lateral position. Depending on the location of the hemivertebral body, an open chest, combined extrapleural retroperitoneal approach via the 11th rib or retroperitoneal approach can be used. The spine is exposed and the segmental vessels on the surface of the hemivertebral body are electrocoagulated to fully expose the hemivertebral body and the two intervertebral discs above and below it. After removing the hemivertebral body, the upper and lower discs, and the cartilage endplates of the adjacent vertebral body, the hemivertebral body is resected posteriorly to the dura and the contralateral disc is removed using a bone knife and spatula. The pedicle is resected as far posteriorly as possible, and the residual space after resection is trimmed to a “V” shape. The dura is covered with gelatin sponge, and the occluded cancellous bone is sparsely implanted in the “V” shaped gap by cutting it into fragments, and the incision is closed by covering it with the pleura or lumbaris major muscle. If the deformity is stiff, two segments of the upper and lower hemivertebral body are released at the same time; for those younger than 10 years old, Risser’s sign is less than I degree, the “Y”-shaped cartilage is not closed or menarche has not yet arrived, epiphyseal block of the upper and lower hemivertebral body is performed at the same time. After suturing the wound, the position was changed to prone with a soft pillow underneath. The posterior structures are exposed according to the preoperative fusion range, and the pedicle nail is driven and temporarily fixed with a rod on the concave side to prevent shear injury to the spinal cord after removal of the posterior structures of the hemivertebral body. The transverse processes, spinous processes, laminae, and some of the remaining pedicles of the hemivertebral body are excised. The laminae of the upper and lower vertebral bodies are appropriately occluded to avoid compression of the dura and spinal cord by the laminae during compression. A rod of appropriate length is pre-bent and attached to the convex lateral nail and pressurized until the lamina gap is basically closed. The dura should be observed at any time during the compression process for obvious folds, and the compression should be stopped when folds are produced, and the vertebral plate should be further occluded to prevent spinal cord injury. Perform arousal test or perform spinal cord monitoring to monitor spinal cord somatosensory evoked potential (SSEP) during the compression process, and lock the device after determining that the spinal cord function is not affected. The device was then locked after placing a rod on the concave side with moderate support. Finally, the dura anteriorly is probed for any posterior displacement of debris bone, and any posteriorly displaced bone should be solidified. Close the incision after performing bone grafting between the vertebral plate, synovial joint and transverse process.
(B) Postoperative treatment: The postoperative day 2 to 5 can be removed from bed. Postoperative wear Boston brace, for uncooperative children generally wear 6 months, some cases depending on the healing and compensatory bending changes appropriate to extend the external fixation time.
3. Efficacy evaluation.
All patients had standing full frontal and lateral spine radiographs taken during the follow-up period. The parietal offset was defined as the vertical distance (cm) from the apex of the scoliosis to the plumb line passing through the C7 spinous process (thoracic bend) or to the sacral midline (lumbar bend/thoracolumbar bend).
4. Results.
The operative time ranged from 140 to 520 min, with a mean of 315 min. intraoperative bleeding ranged from 180 to 1600 ml, with a mean of 798 ml. fixed fusion segments ranged from 2 to 9 segments, with a mean of 4.7 segments. 5 routine 2-segment fixations were performed at a mean age of 10.6 years; all cases were followed up for 24 to 72 months, with a mean of 40.5 months. The coronal Cobb angle was corrected from a mean of 61.7° (30°-90°) to 18.3° (0°-46°) before surgery, with a mean correction rate of 70.3%; the mean was 20.6° at the last follow-up, with a loss of 2.3°. The sagittal Cobb angle was corrected from an average of 48.2° (8° to 118°) preoperatively to 16.6° (0° to 52°); the average was 18.7° at the last follow-up, with a loss of 2.1°. The parietal offset was corrected from an average of 3.7 cm (0.8 to 9 cm) to 1.9 cm (0 to 3.2 cm) preoperatively.
Intraoperative complications included: one case of intraoperative arch cut during compression, which was a longitudinal cut of the left T5 arch after hemivertebral resection of T6, with a 5.5 mm diameter arch nail, which was replaced with a compression fixation after hugging the arch hook and transverse process hook, and no neurological symptoms were found postoperatively.
Distant complications: one patient had loss of lumbar bending, which was a 10-year-old boy with T6 hemivertebrae, Risser’s sign 0 degrees, preoperative lumbar bending 100, and lumbar bending top vertebrae II degree rotation. Considering that fused lumbar curvature can significantly affect the patient’s height and possible varus imbalance. After hemivertebrectomy, only the thoracic curve (T4-T8) was fused, and the lumbar curve was automatically corrected to 70 after surgery, but follow-up revealed that the lumbar curve had gradually increased, and at 3 years after surgery, the lumbar curve was 88, so revision surgery was performed at 37 months after surgery to extend the fusion range (T4-L4). There was no loss of orthosis at 14 months of follow-up after revision surgery. 2 patients developed varus imbalance. Case 1 was a 12-year-old female patient with a T8 hemivertebra, Risser’s sign degree I, and unmenstrual menarche who underwent a one-stage anterior epiphyseal block, hemivertebrectomy, posterior T5-T12 CDH internal fixation, and bone graft fusion. At postoperative follow-up, the lower thoracic curve rotation increased and the lateral convexity arc was prolonged, and a revision surgery was performed at 48 months postoperatively to extend the fusion range (T5-L3). There was no loss of orthosis at the 4-month follow-up after revision surgery. Case 2 was a 5-year-old male patient with a T12 hemivertebra and 0 degree Risser’s sign who underwent a one-stage anterior epiphyseal block, hemivertebral resection, posterior Isola internal fixation at T7-L4, and fusion with bone graft. The postoperative epiphyseal block was performed in two intervertebral spaces above and below the hemivertebral body, and postoperative scoliosis and rotation were gradually aggravated, and an anterior epiphyseal block was performed on all intervertebral spaces within the fusion range at 37 months after revision, and there was no loss of orthosis at 21 months after the operation. The other 16 cases were followed up for an average of 38.2 (24-72) months, and no deformity arc lengthening or internal fixation loosening or fracture was observed.
4. Discussion.
I. Therapeutic results of anterior-posterior hemivertebrectomy.
Royle first described hemivertebrectomy in 1928. in 1979, Leatherman et al. reported 60 anterior-posterior hemivertebrectomies in patients with a mean age of 11 years and a mean correction of scoliosis from 77 to 43 before surgery, obtaining a 44% correction rate. in 1999, Lazar et al. reported 11 patients who underwent one-stage anterior-posterior hemivertebrectomy with a mean correction of scoliosis from 47 to 14 before surgery and a 44% correction rate. In 2006, Bollini et al. reported 34 patients who underwent one-stage anterior and posterior hemilaminectomy and achieved a correction rate of 69.3%. In our group of 20 patients, the correction rate of scoliosis was 70.3%, which is similar to the correction rate reported in the literature and much higher than that of in situ fusion and convex lateral epiphyseal block. Comparison with the degree of scoliosis reported in the literature for cases undergoing posterior hemivertebrectomy showed that anterior-posterior hemivertebrectomy achieved a correction rate similar to that of posterior hemivertebrectomy despite the greater average degree of preoperative scoliosis.
From the literature, it appears that the long-term postoperative orthopedic loss after anterior and posterior hemilaminectomy is less than 5°, especially in the sagittal plane. This is supported by the long-term follow-up results of our group. The reasons for this are mainly related to the complete hemivertebral body resection and the creation of a strong intervertebral fusion in the adjacent vertebrae after hemivertebral body resection. In addition, the release and fusion of the upper and lower 2 segments of the hemivertebral body is also responsible for less orthopedic loss. Therefore, the cartilage endplates of the adjacent vertebral bodies must be completely removed to expose cancellous bone, and the gap remaining after compression must be filled with cancellous bone or the occluded cancellous bone must be loosely implanted into the intervertebral space prior to compression to obtain a firm fusion. The cancellous bone of the hemivertebral body should be preserved as much as possible because of the small amount of bone in young children and the small number of sites available for bone extraction. In this group, we used a bone cutter and spatula to remove the hemivertebral cancellous bone, without grinding drills as much as possible. Usually short-segment fusion with autogenous cancellous bone is sufficient, while multi-segment fusion requires a mixture of allograft bone or artificial bone.
Therefore, anterior and posterior hemivertebrectomy can achieve satisfactory orthopedic results in both the coronal and sagittal planes, and long-term follow-up orthopedic results can still be obtained with the same orthopedic results as posterior hemivertebrectomy in cases of greater scoliosis and stiffness.
II. Complications and prevention of anterior and posterior hemilaminectomy.
Complications of anterior and posterior hemilaminectomy include perioperative pedicle dissection and neurological injury, and long-term complications include loss of compensation and varus imbalance. The most common complication reported in the literature after hemilaminectomy is neurological complications, mostly nerve root compression at the appropriate level, manifesting as transient muscle weakness. holte et al. reported a 20.5% (8/39) incidence of neurological complications, including one case of permanent injury. lazar et al. reported one case of transient lower extremity muscle weakness in 11 cases. king et al. also reported one case of L5 nerve root palsy in seven cases. King et al. also reported 1 case of L5 nerve root palsy in 7 cases. There were no neurological complications in this group, and the main precautions included the need to maintain axial turning when changing from the lateral to prone position intraoperatively. Distal temporary fixation must be performed before posterior resection of the posterior structures of the hemivertebral body in the posterior approach to prevent cut-and-pull injury of the neurospinal cord. Compression should be stopped immediately if the dural sac folds during compression, and the lamina should be further occluded distally and proximally to prevent spinal cord and nerve root compression.
The main cause of intraoperative pedicle dissection is injury to the pedicle caused by the large diameter of the pedicle nail, and the concentration of stress in the short segment fixation and the softness of the child’s bone are also factors in this complication. In order to avoid pedicle cutting, first of all, complete resection of the hemivertebrae should be ensured until there is no obvious resistance to compression; in addition, for the thoracic hemivertebrae, the corresponding level of the costal tuberosity should be resected and the fixation range should be extended appropriately. Finally, for children who may not cooperate after surgery, they should be fixed with a plaster undershirt at the end of surgery to prevent postoperative arch cuts caused by body twisting.
In this group, there were two cases of varus imbalance, both of which were in children with immature bone development. Although an anterior epiphyseal block was performed, postoperative varus imbalance occurred because the block was short in this group, covering only the upper and lower 2 intervertebral spaces of the hemivertebral body and not the entire vertebral body within the fusion arc. Therefore, it is recommended that anterior epiphyseal blocks should include all vertebral bodies within the fusion range as much as possible to prevent such complications.
III. Indications for anterior and posterior hemivertebrectomy.
Compared with posterior hemilaminectomy, anterior-posterior hemilaminectomy requires two surgical incisions, a long operation time, a large trauma, and the risk of intraoperative contamination. Although there were no neurological complications in this group, the incidence of postoperative neurological complications was reported in the literature and was much higher than that of the posterior approach. In contrast, in terms of orthopedic rate, there was no significant difference with posterior hemivertebrectomy. Therefore, with the improvement of surgical techniques, more and more operators tend to prefer posterior hemilaminectomy. However, anterior and posterior hemilaminectomy still has its advantages. For patients with greater degrees and more rigid scoliosis, anterior-posterior hemivertebrectomy allows more complete removal of the hemivertebrae and simultaneous anterior release for better orthopedic and fusion results; for patients with low bone age, epiphyseal block of multiple segments within the range of internal fixation can be performed simultaneously to reduce the occurrence of varus. Therefore, we believe that although posterior hemivertebrectomy is the main surgical treatment method, anterior and posterior hemivertebrectomy still has its indications, i.e., patients with long scoliosis arc, age less than 10 years, Risser’s sign less than II degrees, “Y” shape cartilage not closed or menarche not yet arrived, and patients with large scoliosis, stiffness, and the need for anterior hemivertebrectomy. Patients with large and stiff scoliosis requiring anterior release.
In summary, anterior and posterior hemivertebrectomy can directly remove the deforming factors and achieve the same orthopedic results as posterior hemivertebrectomy, but it has certain neurological complications due to the large trauma. Its indications are gradually narrowing, and it is only applicable to patients who need anterior release for scoliosis stiffness and those who need epiphyseal block for long fusion range with small bone age.