Selective hemivertebrae resection in congenital scoliosis with multiple hemivertebrae

Abstract

There are no established guidelines regarding the surgical strategy to be adopted in congenital scoliosis with multiple hemivertebrae—decision has to be guided taking into account the contribution of each hemivertebra to the deformity and its growth potential. We describe a case of a 12-year-old woman with congenital scoliosis due to unbalanced multiple hemivertebrae. Preoperative imaging revealed the presence of three hemivertebrae—at D7, D10 and L5. Our surgical strategy was guided by various factors—the morphology of the hemivertebrae, the location, the contribution of each hemivertebra to the deformity and their relationship to each other. Based on this, we performed a selective hemivertebrae resection—completely resecting L5 hemivertebra and performing ‘egg-shell’ decancellation of D7 hemivertebra and in situ fusion of D10 hemivertebra, yielding satisfactory results. This case report illustrates a rational thought process that can guide a paediatric spinal deformity surgeon in treating scoliosis with multiple hemivertebrae.

Background

With a reported incidence of 1–10 per 10 000 live births, the presence of a hemivertebra is the most common vertebral anomaly causing congenital scoliosis.^{1 2} Treatment of a hemivertebra ranges from complete surgical resection to complete neglect. Apart from the age of the patient, McMaster and David determined that the progress of deformity depended on the morphology of the hemivertebra, its location, the number of hemivertebrae and their relationship to each other.³ When a single hemivertebra is implicated as a cause, early intervention in the form of hemivertebra resection with short fusion is warranted to halt the progress of the deformity while preserving the growth and mobility of the remaining spine.⁴ However, the management of patients with congenital scoliosis in the presence of multiple hemivertebrae is complex, with no established guidelines available in the literature.

Adopting the same approach of resecting all hemivertebrae would result in unacceptable morbidity and increased complications. A more pragmatic surgical strategy is needed, where each hemivertebra is seen in the context of its contribution to the deformity as well as its potential to progress in future. We describe a case of congenital scoliosis with multiple hemivertebrae while outlining our rationale and surgical strategy of selective hemivertebrae resection used in this case. The purpose is to highlight the factors that need to be considered for deciding the treatment meted out for each hemivertebra, the thought process that a clinician must undertake when dealing with such cases and to demonstrate that a well-executed strategy of selective hemivertebrae resection can produce a satisfactory result with less morbidity.

Case presentation

A short-statured 12-year-old woman presented to us with a spinal deformity. The patient’s parents were short-statured as well. The deformity was noticed 3 years back and had progressed since then. On physical examination (figure 1A–C), a right-sided rib hump was noted corresponding to right-sided thoracic scoliosis. The right shoulder was elevated and the trunk was shifted to the left. The patient was neurologically intact.

Figure 1.

Preoperative clinical photographs of the patient taken from the side (A), while bending forwards (B) and from the back (C). Note the right-sided rib hump (white arrow) and the elevated right shoulder.

Investigations

Preoperative whole spine standing radiographs revealed the presence of three curves (figure 2A, B): a right-sided thoracic curve, a left-sided lumbar curve and a right-sided lumbosacral fractional curve; bending radiographs confirmed that these curves were structural. A careful study of the CT scan showed the presence of three hemivertebrae—at D7, D10 and L5, all on the right side (figure 3A, B). The magnitude (Cobb angle) of the thoracic curve was 70°, whereas that of the lumbar curve was 52°. The clavicle angle was 13°, the radiographic shoulder height difference was 2.5 cm, the coronal shift was 7 mm to the left, the C7 sagittal vertical axis was +7 mm, the Risser grade was 3 and the triradiate cartilage was closed on both sides. No spinal cord abnormality was observed on MRI.

Figure 2.

Preoperative posteroanterior (A) and lateral (B) whole spine radiographs of the patient. Note the presence of multiple hemivertebrae at D7, D10 and L5 (white arrows).

Figure 3.

Preoperative CT scan images showing the presence of multiple hemivertebrae at D7, D10 and L5.

Treatment

The entire surgery was performed by a single-stage, posterior approach, with the patient positioned prone, under general anaesthesia and multimodality intraoperative neuromonitoring. A standard midline exposure was done from D3 to S2—anchors were placed from D3 to pelvis, including S2-alar-iliac screws as the most distal anchors. Fluoroscopy was used to confirm the location of each hemivertebra. Each hemivertebra was dealt with keeping in mind its location, morphology, contribution to the existing deformity and its potential to progress. The hemivertebra at L5 was a part of the lumbosacral fractional curve—addressal of this curve was of utmost importance as malalignment at this level translates into greater effects up the spinal column. Progress of deformity at the lumbosacral junction would lead to the entire spine taking off obliquely from the sacrum.³ In light of this, we performed a complete resection of the L5 hemivertebra—this was spanned by two short rods with compression done on the convex side to close the gap. The hemivertebra at D7 was located at the apex of the thoracic curve and contributed the most to the deformity and shoulder imbalance. At this level, we performed an ‘egg-shell’ decancellation osteotomy that has been previously described⁵—the pedicle was cannulated with a high-speed drill following which cancellous bone from the body of hemivertebra was removed using pedicle awl, tap and angled curettes. This left only a thin cortical rim of bone which crumbled as the osteotomy was closed. Opting for a decancellation procedure instead of complete resection obviated the need to resect the rib—lessening the risk of pulmonary complications while producing similar correction. The hemivertebra at D10 was neither at the apex nor at the end of the curve and did not contribute to the present deformity; hence, it was fused in situ. Uniaxial screws were used around the apex in both thoracic and lumbar curves to correct rotation. Multiple posterior column osteotomies at other levels were used as adjuncts to mobilise each segment. Long titanium rods were connected to the anchors—and connected to the short rods that spanned the L5 hemivertebra resection site by rod-to-rod connectors. Locally harvested bone graft from the excised and decancellated hemivertebrae was applied. The estimated blood loss was 450 mL and the operative duration was 220 min.

Outcome and follow-up

The patient had an uneventful recovery in the postoperative period—the Cobb angle of the thoracic curve was corrected to 39° and that of the lumbar curve was corrected to 3°. Both the shoulders were level and the coronal shift was corrected to 2 mm towards the right (figure 4A, B). The Scoliosis Research Society (SRS)-22r functional score improved from 3.7/5 preoperatively to 4.2/5 at the final follow-up. No loss of correction or implant-related complication was seen at the final follow-up of 24 months (figures 5A–C and 6A, B).

Figure 4.

Immediate postoperative posteroanterior (A) and lateral (B) radiographs of the patient.

Figure 5.

Postoperative clinical photographs of the patient taken from the side (A), while bending forwards (B) and from the back (C) at final follow-up.

Figure 6.

Postoperative posteroanterior (A) and lateral (B) whole spine radiographs of the patient (at final follow-up).

Discussion

Scoliosis due to unbalanced multiple hemivertebrae is expected to progress at a rate of 2°−5° per year, which is higher than a single hemivertebra (1°−3.5° per year).⁶ Management of these patients is more challenging compared with patients with a single hemivertebra—various factors need to be taken into account to decide which hemivertebra should be preserved or resected. Fully segmented, non-incarcerated hemivertebrae progress most rapidly, whereas an incarcerated hemivertebra has poor growth potential.³ A hemivertebra in the upper thoracic region progresses slowly, but can cause significant cosmetic deformity and shoulder imbalance. On the contrary, hemivertebra in the thoracolumbar region progresses rapidly, but the cosmetic deformity produced is less severe. Lumbosacral hemivertebrae can cause the lumbar spine to take off obliquely from the sacrum and lead to secondary structural curve in the lumbar/thoracolumbar region. When more than one hemivertebra is present on the same side, the deformity progresses even more rapidly; however, when they are on opposing sides, the prognosis depends on their relationship with each other.³

Zhou et al⁷ reported the results of hemivertebra resection in unbalanced multiple hemivertebrae in 12 children. An 80% correction rate was observed for the main curve, and both coronal and sagittal imbalance improved after surgery. The mean operating time reported in their case series was 282.1 min and the mean blood loss was 754.2 mL. Selective hemivertebrae resection in a case of congenital scoliosis with multiple hemivertebrae was first described by Zhang et al.⁸ The authors described the factors that merit consideration in the surgical decision-making in such a case—and achieved good correction of the curve and restoration of coronal and sagittal balance with their strategy. We approached our case with the twin goals of halting the progress of the deformity and correcting the deformity to address the patient’s cosmetic concern. A single posterior approach was used; a combined anterior-posterior approach in such cases would greatly increase the morbidity, particularly when hemivertebrae are in different regions of the spine. We describe how we factored in the location, morphology and contribution to the deformity for each hemivertebrae—and based on our assessment, meted out three different treatments, namely, complete resection (L5), decancellation procedure (D7) and fusion in situ (D10).

Patient’s perspective.

My wife first noticed that there was something wrong in my daughter’s back when she was helping her get dressed up for school—my daughter had just turned 9, a week before that. We thought initially that it was a problem related to faulty posture. However, over the next 2 years, the shape of her back changed even more —she now complained that her school friends had also started noticing it and she often became a subject of fun and ridicule due to the same. She also complained that when she carried her school bag over her shoulders, she felt that all the weight was being placed on her right shoulder. It was then that my wife noticed that her left shoulder was in fact drooping down. We visited our family physician who examined her and ordered an X-ray examination. We were told that our daughter had a curved spine and needed a specialist to see her. My daughter had begun to avoid playing with her schoolmates and was no longer as enthusiastic about going to school as she always was.

The specialists ordered some more investigations and then told us that my daughter needed surgery. They explained that the primary objective of the surgery was to halt the progress of the deformity since it was expected to grow for a few more years. Improving the appearance of her back was a secondary objective. We were explained regarding the risks involved. The surgical procedure went smoothly—as did the postoperative recovery. Two years after her surgery, my daughter has forgotten that she ever had a bent spine!

Learning points.

• This case highlights how a rationally formulated surgical strategy involving selective hemivertebrae resection can achieve a satisfactory clinical and radiological outcome in a patient with congenital scoliosis due to unbalanced multiple hemivertebrae with reduced morbidity.

• Various factors should be taken into account when guiding the treatment of such cases: morphology of the vertebral anomaly, location, remaining potential for growth and its contribution to the deformity.

• Close follow-up should be done to look for possible decompensation of the deformity.