Congenital defects usually have serious consequences in spinal growth. The severity of the congenital deformity depends on the type of anomaly, the site at which it occurred, and the overall growth potential of the individual. Without any treatment 85% of the patients will have spinal curves exceeding 41 degrees [1]. The non-surgical treatment is rarely successful. Seventy five percent of the curves are progressive and only 5 to 10% can be treated with bracing [2]. Winter studied the natural history and progression of congenital scoliosis on 234 patients and also classified them [34]. The classification was further modified and elaborated by McMaster, where the congenital vertebral anomalies were classified into four types (type I to III and unclassified) [5]. Hemivertebra excision is a safe and effective procedure for congenital scoliosis and results are better with early surgery [67]. However, results of multi-level hemivertebrectomies have not been reported. The present retrospective analysis assessed the outcome of 22 patients with congenital kyphoscoliosis who underwent one-stage posterior resection and short segment pedicle screw fixation in our centre.

Data of the 22 patients who underwent a single stage posterior hemivertebra resection and transpedicular fixation with a minimum two-year follow-up were analysed retrospectively (Table 1). There were nine male and 13 female patients. The mean age was 11.2 years (range, 2 years 4 months to 24 years 10 months). All the patients were evaluated with AP and lateral X-rays, computed tomography (CT) and magnetic resonance imaging (MRI) of the spine, and had been screened for associated congenital anomalies. 15 of 22 patients (68.2%) had pure failure of formation (type I anomaly) [5] while three were type III and four were type IV. Three of the 15 type I anomaly patients had two segmented hemivertebrae at two levels and one patient had three hemivertebrae (two segmented and one semi segmented), for a total of 20 hemivertebrae. Of these 20, 14 were segmented vertebrae and six were semi-segmented (Table 1). Among the remaining seven patients (31.8%), three (13.6%) had mixed (type III) defects (anterolateral bar associated with posterolateral hemivertebrae) and four (18.2%) had unclassifiable anomalies (type IV). None of the patients having type II defect required surgery. Of the 22 patients, two (9%) had associated foot/leg weakness and calf muscle atrophy. They had equino-varus deformity that was surgically corrected by a paediatric orthopaedic surgeon. Four patients (18.1%) had other congenital anomalies that included rectovaginal fistula and tethered cord, rectovestibular fistula, ileal atresia, and Tetrology of Fallot's in one case each (Table 1).

The mean operating time was 300 minutes (range, 150 to 400 minutes). The mean blood loss during the surgery was 611 mL (range, 200 to 1,300 mL). The mean duration of hospital stay was 10.4 days (range, 6 to 15 days).

All studies focussing on the congenital scoliosis have clearly pointed out that without treatment the outcome usually is unacceptable [8]. Of the untreated cases, only 10% have a curve of ≤20°—and 64% have curves that are greater than 40 degrees [1]. With increasing time, the deformities become more structural and maximum corgrection is achieved when the patient is operated on early (preferably before 5 years) [9]. In our series the mean age was 11.2 years with only seven patients (31.8%) <5 years of age. The mean sagittal (59.8% vs. 35.1%, p=0.03) and coronal (56.2% vs. 40.3%, p=0.02) correction was achieved in patients >5 years of age. This could be because five of seven of the patients <5 years of age had hemivertebrae present in the dorsal spine, where correction is difficult to achieve because of crowding and deformity of the ribs.

Posterior fusion is the simplest method in which the spine was fused from endvertebra to end-vertebra of the curve, posteriorly. Winter reported the bending of fusion mass posteriorly causing worsening in about 14% of cases [2]. Kesling et al. [10] reported a value of 15%. Hall et al. [11] reported that addition of Harrington instrumentation was a solution, allowing maintenance of the reduction achieved at the operative table as compared to postoperative casting, as well as reducing the incidence of pseudoarthosis.

The first excision of a hemivertebra from the front was performed in 1928 by Royle [12], followed later by Compere [13] and Von Lackum and Smith [14] in the lumbar spine. Wiles [15] performed thoracic spine surgery using a posterolateral approach by resecting ribs in two children but the patients developed kyphosis. Excision of the hemivertebrae as a two-stage procedure became popular [1617]. Bradford and Boachie-Adje [7] reported that the procedure can be done in a single stage. They described the procedure in seven patients who were treated with a single-stage anterior and posterior arthrodesis; approximately 70% correction was achieved after an average follow-up of 45.6 months. Kokubun et al. [18] and Leatherman [19] also reported single-stage anterior-posterior hemivertebrectomy as a safe and efficacious procedure.

However, the morbidity and complications of the anterior approach remain concerns. Wang et al. [20] retrospectively analysed 60 patients divided equally in single-stage anterior-posterior and posterior only group and analysed them with respect to operation time, blood loss, degree of correction of the main curve/segmental curve/kyphosis, average hospital stay, and complications. Mean operation time, blood loss, and hospital stay were significantly less in the posterior only group. The average correction rate of the main curve/segmental curve/kyphosis of the anterior-posterior group was marginally better (p>0.05). However, the author reported a complication rate of 6.7% in the former group vs. 10% in the posterior group (p>0.05), of which two-thirds were radiculopathies. We did not have any permanent nerve/cord injury because all the cases were done under intraoperative neurophysiological monitoring.

Shono et al. [21] retrospectively studied 12 patients 8 to 24 years of age with congenital kyphoscoliosis caused by a single hemivertebra. Preoperative scoliosis and kyphosis averaging 49° and 40° was corrected to 18° and 17°, respectively. The author concluded that single-stage posterior hemivertebrectomy is safe and effective in structural kyphoscoliotic deformity caused by a thoracic or thoracolumbar single hemivertebra. In our series, the maximum correction immediate postoperatively in both sagittal and coronal planes was achieved in thoracolumbar hemivertebrae followed by lumbar hemivertebrae followed by thoracic hemivertebrae. Correction was maintained at the last follow-up. This is attributable to the fact that in the thoracic region the deformity correction is resisted by the presence of deformed ribs and chest wall, whereas in the lumbar region the vertebrae are bigger and the ligaments are stronger, and so are able to resist correction. The thoracolumbar junction being a transition zone has floating ribs and relatively smaller vertebrae and weaker ligaments.

In a multi-center trial, Yaszay et al. [22] compared three modalities: hemiepiphysiodesis or in situ fusion, instrumented fusion without hemivertebra excision, and instrumented hemivertebra excision. The conclusion was that posterior hemivertebra resection in younger patients resulted in better percent correction than the other two techniques, although it also was associated with higher complication rate. However, despite some of its limitations posterior resection of hemivertebrae with transpedicular instrumentation is a safe and promising procedure [23]. Using a posterior-only approach we were able to correct deformity caused by hemivertebra at the single, two, and three levels. The deformity correction was maximum in three-level hemivertebrectomy in both the sagittal and coronal planes (Table 3).

The pedicle screw instrumentation quite safe in juvenile and adolescents [2425]. Harimaya et al. [26] reported 99% accuracy of pedicle screw placement in juvenile and children with no intraoperative or short-term screw-related complications. We did not have any implant related complications in our series.

Posterior hemivertebrectomy is a safe and effective procedure for congenital scoliosis. Single, two, and three-level hemivertebrae can be safely removed with good correction of deformity.