For the past several decades, many surgeons have treated severe pediatric and adult spinal deformities with a circumferential approach. However, the recent ability to treat these deformities through an all-posterior VCR has obviated the need for a circumferential approach in primary and revision surgery. To confirm the appropriateness of the VCR approach, the purposes of our study were therefore to (1) describe our experience along with the surgical technique and radiographic and clinical results; (2) define the perioperative and postoperative morbidity; and (3) report complications of this approach. Through this description, we also hoped to describe the pearls, pitfalls, and warning signs associated with this procedure.
Our study had several limitations. First is the heterogeneity in the patient diagnoses and conditions. Second, we had no control group of untreated patients or those with alternative surgical approaches. Both of these limitations relate to the extremely rare and unusual clinical presentation of these types of severe spinal deformity patterns. Third, the followup is short on some of the patients; however, we believe it important to provide complete accounting of all intraoperative and early (1 to 2 months postoperative) complications in these patients and that would have been lost had we excluded patients with short followup.
The use of a vertebrectomy procedure has been around for quite some time with the first description in 1922 by MacLennan who described a posterior apical resection followed by postoperative casting for the treatment of severe scoliosis [13
]. After that, several authors recorded their experiences with vertebrectomies, most commonly for the surgical treatment of congenital scoliosis [3
]. In the modern era of spinal deformity surgery, Bradford was the first to describe the use of a circumferential vertebrectomy on patients with severe structural spinal deformities [2
]. His report consisted of 13 patients who underwent a one-to seven-level (average, three levels) vertebrectomy. Patients with scoliosis had a preoperative curve averaging 117°, correcting to an average 55°. Patients with kyphosis had a preoperative curve averaging 112°, correcting to an average 56°. The average estimated blood loss was 5800 mL, and the average operative time was 10.5 hours for these combined procedures. Bradford and Tribus later reported 24 patients with rigid coronal decompensation who underwent a circumferential VCR [3
]. The average preoperative scoliosis was 103° corrected by 52%. Importantly, coronal and sagittal imbalances were corrected to an average of 82% and 87%, respectively. However, there was an average operative time of over 12 hours, an average blood loss of 5500 mL, and 31 overall complications.
Suk et al. [17
] first promoted a posterior-only VCR. They believed the total operating time and blood loss was reduced through this one-stage posterior-only procedure. In 2005, Suk et al. reported 16 patients (average age, 29 years) who underwent a posterior VCR having a minimum 2-year followup [15
]. Their indication for this procedure was scoliosis of more than 80° with flexibility less than 25%. There was an average of 1.3 vertebrae removed, 15 performed in the thoracic spine and six performed in the lumbar spine. The mean preoperative scoliosis of 109° was corrected to 46° (59% correction). However, complications were encountered in four patients, including one with complete permanent paralysis. Suk et al. [15
] recommended this as an effective alternative for severe rigid scoliosis but cautioned that it was a highly technical procedure and should only be performed by an experienced surgical team. It is important to note, he did not use any form of motor tract monitoring during the surgeries, only SSEP monitoring. Our series of 43 patients undergoing posterior-only VCR for severe pediatric and adult spinal deformity is both complimentary and additive to these prior reports. The severe scoliosis cases had a correction rate of 69%, 54% for the global kyphosis cases, 63% for the angular kyphosis cases, and 56% for the combined kyphoscoliosis cases, which is as good as or better than other correction rates reported in the literature by either circumferential or posterior-only vertebrectomy (Table ).
Comparisons to the literature
We identified no spinal cord-related neurologic deficits in any of the patients in this series. We attribute this to several factors, including the routine use of NMEP monitoring in those patients who had available spinal cord monitoring potentials (40 of 43). Seven patients lost NMEP data some time during the surgical procedure, most commonly during the actual spinal shortening and correction. The most common reason for lost NMEP data was spinal subluxation, which can occur before, during, or even after the corrective procedure. The spine is rendered extremely unstable during this posterior reconstruction and thus it is imperative to regain primary stability with a dural sac that is free from compression and not excessively shortened ventrally (especially during kyphotic reconstructions). In three patients (two with and one without available spinal cord monitoring), overshortening of the ventral spinal cord led to the loss of data in one and a failed wake-up test in the other. Restoring appropriate anterior height through a larger anterior cage restored the NMEP data in two and neurologic function in the other. We also strongly believe it is important to maintain normotensive anesthesia during correction and closure of these deformities. We prefer to have the mean arterial pressure at least 75 to 80 mmHg during this time. Occasionally, this will require the adjunctive use of dopamine as a low-dose inotrope and providing blood products as needed. As one might anticipate, the occurrence of NMEP data loss was in patients with a primary or secondary kyphotic malalignment to the spine with the highest risk being the angular kyphosis group.
As evidenced by prior reports, these surgeries have a very high neurologic risk. This is in part the result of the severe nature of the deformity and in part the result of the instability created to correct these deformities with segmental instrumentation [12
]. Thus, we believe it imperative to use intraoperative spinal cord monitoring with some form of motor tract monitoring to provide early detection of data loss, which allows for immediate correction of the cause. In our series, we were fortunate to have the NMEP data return quickly with the aid of prompt and precise surgical techniques in the seven cases that lost data out of the 40 cases that had monitoring. Although difficult to prove, it is certainly realistic that our neurologic complication rate would have been much higher without the early detection that is obtainable with the use of multimodality SCM.
The contraindications for this procedure would be (1) surgeon unfamiliarity with this advanced technique; (2) ability to obtain adequate deformity correction with a less invasive approach (eg, posterior column-based osteotomies alone); and (3) inability to obtain spinal cord monitoring data (relative contraindication), which would create an increased neurologic risk during the surgery and require multiple wake-up tests to be performed.
The surgical treatment of severe spinal deformity is challenging. Traditionally, a circumferential approach with anterior releases through discectomies followed by posterior instrumentation and fusion has been the standard of care. A posterior-based VCR is a safe but challenging technique for treating severe primary or revision pediatric and adult spinal deformity. Intraoperative spinal cord monitoring, especially some form of motor tract monitoring, is mandatory to prevent spinal cord-related neurologic complications. This posterior-only approach also allows for dramatic radiographic and clinical correction of these severely deformed patients.