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Faiz U. Ahmad and Michael Y. Wang

Object

Over the past decade percutaneous pedicle screws have become popular for the minimally invasive treatment of spinal disorders. However, until the last 5 years the presence of a significant spinal deformity was regarded as a relative contraindication for percutaneous instrumentation. Recent advances in surgical technique and intraoperative technology have made percutaneous fixation in complex spinal pathologies more commonplace. The authors report their experience using a parsimonious method for uniplanar fluoroscopic targeting of pedicles in challenging cases.

Methods

The authors performed a retrospective analysis of patients with adult spinal deformity who underwent percutaneous pedicle screw instrumentation from 2008 to 2013. Cases were included if a spiral slice postoperative CT scan was obtained. All cases had a minimum of 10° of axial rotation and typically had additional accompanying anatomical abnormalities. Screws were assessed for any pedicle violations as well as any impingement of the surrounding facet joints.

Results

A total of 410 pedicle screws were placed in 36 patients with an average 6.4 levels of instrumentation per patient. The mean age was 67 years (range 44–86 years) and there were 25 females. Of the 410 screws, 29 (7.1%) had some medial or lateral pedicle violation. Of these, 15 (3.7%) were Grade 1, 6 (1.4%) were Grade 2, and 8 (2.0%) were Grade 3 violations. Of the Grade 3 violations, 2 each were at the L-4, L-5, and S-1 levels, and 1 each was at the T-10 and L-1 levels. Two of the patients had symptoms and both underwent screw repositioning, one during the same admission and the other in a delayed fashion. Both were at the L-5 and S-1 levels with anatomically highly medialized pedicles. There were no motor deficits, and both removals were for numbness. Of the 72 screws at the proximal end of the construct, there were 6 facet violations (8.3%). Four (5.6%) of these were Grade 1, 1 (1.4%) was Grade 2, and 1 (1.4%) was Grade 3.

Conclusions

The anteroposterior fluoroscopic technique can be effectively used by spinal surgeons to cannulate the pedicles in patients with rotational deformities. The complication rate in this challenging population is acceptable and is in accordance with the existing literature. However, caution should be used at L-5 and S-1 when the pedicle is narrow and highly medialized, rendering an indistinct medial wall on anteroposterior imaging.

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Patrick C. Hsieh, John C. Liu and Michael Y. Wang

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Sanjay S. Dhall, Rishi Wadhwa, Michael Y. Wang, Alexandra Tien-Smith and Praveen V. Mummaneni

Object

Minimally invasive spinal (MIS) surgery techniques have been used sporadically in thoracolumbar junction trauma cases in the past 5 years. A review of the literature on the treatment of thoracolumbar trauma treated with MIS surgery revealed no unifying algorithm to assist with treatment planning. Therefore, the authors formulated a treatment algorithm.

Methods

The authors reviewed the current literature on MIS treatment of thoracolumbar trauma. Based on the literature review, they then created an algorithm for the treatment of thoracolumbar trauma utilizing MIS techniques. This MIS trauma treatment algorithm incorporates concepts form the Thoracolumbar Injury Classification System (TLICS).

Results

The authors provide representative cases of patients with thoracolumbar trauma who underwent MIS surgery utilizing the MIS trauma treatment algorithm. The cases involve the use of mini-open lateral approaches and/or minimally invasive posterior decompression with or without fusion.

Conclusions

Cases involving thoracolumbar trauma can safely be treated with MIS surgery in select cases of burst fractures. The role of percutaneous nonfusion techniques remains very limited (primarily to treat thoracolumbar trauma in patients with a propensity for autofusion [for example, those with ankylosing spondylitis]).

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Raqeeb M. Haque, Gregory M. Mundis Jr., Yousef Ahmed, Tarek Y. El Ahmadieh, Michael Y. Wang, Praveen V. Mummaneni, Juan S. Uribe, David O. Okonkwo, Robert K. Eastlack, Neel Anand, Adam S. Kanter, Frank La Marca, Behrooz A. Akbarnia, Paul Park, Virginie Lafage, Jamie S. Terran, Christopher I. Shaffrey, Eric Klineberg, Vedat Deviren and Richard G. Fessler

Object

Various surgical approaches, including open, minimally invasive, and hybrid techniques, have gained momentum in the management of adult spinal deformity. However, few data exist on the radiographic outcomes of different surgical techniques. The objective of this study was to compare the radiographic and clinical outcomes of the surgical techniques used in the treatment of adult spinal deformity.

Methods

The authors conducted a retrospective review of two adult spinal deformity patient databases, a prospective open surgery database and a retrospective minimally invasive surgery (MIS) and hybrid surgery database. The time frame of enrollment in this study was from 2007 to 2012. Spinal deformity patients were stratified into 3 surgery groups: MIS, hybrid surgery, and open surgery. The following pre- and postoperative radiographic parameters were assessed: lumbar major Cobb angle, lumbar lordosis, pelvic incidence minus lumbar lordosis (PI−LL), sagittal vertical axis, and pelvic tilt. Scores on the Oswestry Disability Index (ODI) and a visual analog scale (VAS) for both back and leg pain were also obtained from each patient.

Results

Of the 234 patients with adult spinal deformity, 184 patients had pre- and postoperative radiographs and were thus included in the study (MIS, n = 42; hybrid, n = 33; open, n = 109). Patients were a mean of 61.7 years old and had a mean body mass index of 26.9 kg/m2. Regarding radiographic outcomes, the MIS group maintained a significantly smaller mean lumbar Cobb angle (13.1°) after surgery compared with the open group (20.4°, p = 0.002), while the hybrid group had a significantly larger lumbar curve correction (26.6°) compared with the MIS group (18.8°, p = 0.045). The mean change in the PI−LL was larger for the hybrid group (20.6°) compared with the open (10.2°, p = 0.023) and MIS groups (5.5°, p = 0.003). The mean sagittal vertical axis correction was greater for the open group (25 mm) compared with the MIS group (≤ 1 mm, p = 0.008). Patients in the open group had a significantly larger postoperative thoracic kyphosis (41.45°) compared with the MIS patients (33.5°, p = 0.005). There were no significant differences between groups in terms of pre- and postoperative mean ODI and VAS scores at the 1-year follow-up. However, patients in the MIS group had much lower estimated blood loss and transfusion rates compared with patients in the hybrid or open groups (p < 0.001). Operating room time was significantly longer with the hybrid group compared with the MIS and open groups (p < 0.001). Major complications occurred in 14% of patients in the MIS group, 14% in the hybrid group, and 45% in the open group (p = 0.032).

Conclusions

This study provides valuable baseline characteristics of radiographic parameters among 3 different surgical techniques used in the treatment of adult spinal deformity. Each technique has advantages, but much like any surgical technique, the positive and negative elements must be considered when tailoring a treatment to a patient. Minimally invasive surgical techniques can result in clinical outcomes at 1 year comparable to those obtained from hybrid and open surgical techniques.

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Juan S. Uribe, Armen R. Deukmedjian, Praveen V. Mummaneni, Kai-Ming G. Fu, Gregory M. Mundis Jr., David O. Okonkwo, Adam S. Kanter, Robert Eastlack, Michael Y. Wang, Neel Anand, Richard G. Fessler, Frank La Marca, Paul Park, Virginie Lafage, Vedat Deviren, Shay Bess and Christopher I. Shaffrey

Object

It is hypothesized that minimally invasive surgical techniques lead to fewer complications than open surgery for adult spinal deformity (ASD). The goal of this study was to analyze matched patient cohorts in an attempt to isolate the impact of approach on adverse events.

Methods

Two multicenter databases queried for patients with ASD treated via surgery and at least 1 year of follow-up revealed 280 patients who had undergone minimally invasive surgery (MIS) or a hybrid procedure (HYB; n = 85) or open surgery (OPEN; n = 195). These patients were divided into 3 separate groups based on the approach performed and were propensity matched for age, preoperative sagittal vertebral axis (SVA), number of levels fused posteriorly, and lumbar coronal Cobb angle (CCA) in an attempt to neutralize these patient variables and to make conclusions based on approach only. Inclusion criteria for both databases were similar, and inclusion criteria specific to this study consisted of an age > 45 years, CCA > 20°, 3 or more levels of fusion, and minimum of 1 year of follow-up. Patients in the OPEN group with a thoracic CCA > 75° were excluded to further ensure a more homogeneous patient population.

Results

In all, 60 matched patients were available for analysis (MIS = 20, HYB = 20, OPEN = 20). Blood loss was less in the MIS group than in the HYB and OPEN groups, but a significant difference was only found between the MIS and the OPEN group (669 vs 2322 ml, p = 0.001). The MIS and HYB groups had more fused interbody levels (4.5 and 4.1, respectively) than the OPEN group (1.6, p < 0.001). The OPEN group had less operative time than either the MIS or HYB group, but it was only statistically different from the HYB group (367 vs 665 minutes, p < 0.001). There was no significant difference in the duration of hospital stay among the groups. In patients with complete data, the overall complication rate was 45.5% (25 of 55). There was no significant difference in the total complication rate among the MIS, HYB, and OPEN groups (30%, 47%, and 63%, respectively; p = 0.147). No intraoperative complications were reported for the MIS group, 5.3% for the HYB group, and 25% for the OPEN group (p < 0.03). At least one postoperative complication occurred in 30%, 47%, and 50% (p = 0.40) of the MIS, HYB, and OPEN groups, respectively. One major complication occurred in 30%, 47%, and 63% (p = 0.147) of the MIS, HYB, and OPEN groups, respectively. All patients had significant improvement in both the Oswestry Disability Index (ODI) and visual analog scale scores after surgery (p < 0.001), although the MIS group did not have significant improvement in leg pain. The occurrence of complications had no impact on the ODI.

Conclusions

Results in this study suggest that the surgical approach may impact complications. The MIS group had significantly fewer intraoperative complications than did either the HYB or OPEN groups. If the goals of ASD surgery can be achieved, consideration should be given to less invasive techniques.

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Adam S. Kanter, Christopher I. Shaffrey, Praveen Mummaneni, Michael Y. Wang and Juan S. Uribe

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Michael Y. Wang, Praveen V. Mummaneni, Kai-Ming G. Fu, Neel Anand, David O. Okonkwo, Adam S. Kanter, Frank La Marca, Richard Fessler, Juan Uribe, Christopher I. Shaffrey, Virginie Lafage, Raqeeb M. Haque, Vedat Deviren and Gregory M. Mundis Jr.

Object

Minimally invasive surgery (MIS) options for the treatment of adult spinal deformity (ASD) have advanced significantly over the past decade. However, a wide array of options have been described as being MIS or less invasive. In this study the authors investigated a multiinstitutional cohort of patients with ASD who were treated with less invasive methods to determine the extent of deformity correction achieved.

Methods

This study was a retrospective review of multicenter prospectively collected data in 85 consecutive patients with ASD undergoing MIS surgery. Inclusion criteria were as follows: age older than 45 years; minimum 20° coronal lumbar Cobb angle; and 1 year of follow-up. Procedures were classified as follows: 1) stand-alone (n = 7); 2) circumferential MIS (n = 43); or 3) hybrid (n = 35).

Results

An average of 4.2 discs (range 3–7) were fused, with a mean follow-up duration of 26.1 months in this study. For the stand-alone group the preoperative Cobb range was 22°–51°, with 57% greater than 30° and 28.6% greater than 50°. The mean Cobb angle improved from 35.7° to 30°. A ceiling effect of 23° for curve correction was observed, regardless of preoperative curve severity. For the circumferential MIS group the preoperative Cobb range was 19°–62°, with 44% greater than 30° and 5% greater than 50°. The mean Cobb angle improved from 32° to 12°. A ceiling effect of 34° for curve correction was observed. For the hybrid group the preoperative Cobb range was 23°–82°, with 74% greater than 30° and 23% greater than 50°. The mean Cobb angle improved from 43° to 15°. A ceiling effect of 55° for curve correction was observed.

Conclusions

Specific procedures for treating ASD have particular limitations for scoliotic curve correction. Less invasive techniques were associated with a reduced ability to straighten the spine, particularly with advanced curves. These data can guide preoperative technique selection when treating patients with ASD.

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Praveen V. Mummaneni, Christopher I. Shaffrey, Lawrence G. Lenke, Paul Park, Michael Y. Wang, Frank La Marca, Justin S. Smith, Gregory M. Mundis Jr., David O. Okonkwo, Bertrand Moal, Richard G. Fessler, Neel Anand, Juan S. Uribe, Adam S. Kanter, Behrooz Akbarnia and Kai-Ming G. Fu

Object

Minimally invasive surgery (MIS) is an alternative to open deformity surgery for the treatment of patients with adult spinal deformity. However, at this time MIS techniques are not as versatile as open deformity techniques, and MIS techniques have been reported to result in suboptimal sagittal plane correction or pseudarthrosis when used for severe deformities. The minimally invasive spinal deformity surgery (MISDEF) algorithm was created to provide a framework for rational decision making for surgeons who are considering MIS versus open spine surgery.

Methods

A team of experienced spinal deformity surgeons developed the MISDEF algorithm that incorporates a patient's preoperative radiographic parameters and leads to one of 3 general plans ranging from MIS direct or indirect decompression to open deformity surgery with osteotomies. The authors surveyed fellowship-trained spine surgeons experienced with spinal deformity surgery to validate the algorithm using a set of 20 cases to establish interobserver reliability. They then resurveyed the same surgeons 2 months later with the same cases presented in a different sequence to establish intraobserver reliability. Responses were collected and tabulated. Fleiss' analysis was performed using MATLAB software.

Results

Over a 3-month period, 11 surgeons completed the surveys. Responses for MISDEF algorithm case review demonstrated an interobserver kappa of 0.58 for the first round of surveys and an interobserver kappa of 0.69 for the second round of surveys, consistent with substantial agreement. In at least 10 cases there was perfect agreement between the reviewing surgeons. The mean intraobserver kappa for the 2 surveys was 0.86 ± 0.15 (± SD) and ranged from 0.62 to 1.

Conclusions

The use of the MISDEF algorithm provides consistent and straightforward guidance for surgeons who are considering either an MIS or an open approach for the treatment of patients with adult spinal deformity. The MISDEF algorithm was found to have substantial inter- and intraobserver agreement. Although further studies are needed, the application of this algorithm could provide a platform for surgeons to achieve the desired goals of surgery.

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Christoph P. Hofstetter and Michael Y. Wang