The incidence of surgical site infections and vascular and visceral complications following MIS-LIF in this large series was low and compared favorably with rates for alternative interbody fusion approaches. Although technically demanding, MIS-LIF is a reproducible approach for interbody fusion with a low risk of vascular and visceral complications and infections.

There is underreporting of postoperative lumbar plexus nerve injury and a lack of standardization of clinical findings of neural complications related to the minimally invasive lateral retroperitoneal transpsoas approach. The authors provide a diagnostic paradigm that allows for an efficient and accurate classification of postoperative lumbar plexopathies and nerve injuries.

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.

The object of this study was to evaluate a novel surgical technique in the treatment of adult degenerative scoliosis and present our early experience with the minimally invasive lateral approach for anterior longitudinal ligament release to provide lumbar lordosis and examine its impact on sagittal balance. Methods. All patients with adult spinal deformity (ASD) treated with the minimally invasive lateral retroperitoneal transpsoas interbody fusion (MIS LIF) for release of the anterior longitudinal ligament were examined. Patient demographics, clinical data, spinopelvic parameters, and outcome measures were recorded. Results. Seven patients underwent release of the anterior longitudinal ligament (ALR) to improve sagittal imbalance. All cases were split into anterior and posterior stages, with mean estimated blood loss of 125 cc and 530 cc, respectively. Average hospital stay was 8.3 days, and mean follow-up time was 9.1 months. Comparing pre- and postoperative 36′′ standing X-rays, the authors discovered a mean increase in global lumbar lordosis of 24 degrees, increase in segmental lumbar lordosis of 17 degrees per level of ALL released, decrease in pelvic tilt of 7 degrees, and decrease in sagittal vertical axis of 4.9 cm. At the last followup, there was a mean improvement in VAS and ODI scores of 26.2% and 18.3%. Conclusions. In the authors' early experience, release of the anterior longitudinal ligament using the minimally invasive lateral retroperitoneal transpsoas approach may be a feasible alternative in correcting sagittal deformity.

Object Minimally invasive (MI) fusion and instrumentation techniques are playing a new role in the treatment of adult spinal deformity. The open pedicle subtraction osteotomy (PSO) and Smith-Petersen osteotomy (SPO) are proven segmental methods for improving regional lordosis and global sagittal parameters. Recently the MI anterior column release (ACR) was introduced as a segmental method for treating sagittal imbalance. There is a paucity of data in the literature evaluating the alternatives to PSO and SPO for sagittal balance correction. Thus, the authors conducted a preliminary retrospective radiographic review of prospectively collected data from 2009 to 2012 at a single institution. The objectives of this study were to: 1) investigate the radiographic effect of MI-ACR on spinopelvic parameters, 2) compare the radiographic effect of MI-ACR with PSO and SPO for treatment of adult spinal deformity, and 3) investigate the radiographic effect of percutaneous posterior spinal instrumentation on spinopelvic parameters when combined with MI transpsoas lateral interbody fusion (LIF) for adult spinal deformity. Methods: Patient demographics and radiographic data were collected for 36 patients (9 patients who underwent MI-ACR and 27 patients who did not undergo MI-ACR). Patients included in the study were those who had undergone at least a 2-level MI-LIF procedure; adequate preoperative and postoperative 36-inch radiographs of the scoliotic curvature; a separate second-stage procedure for the placement of posterior spinal instrumentation; and a diagnosis of degenerative scoliosis (coronal Cobb angle > 10° and/or sagittal vertebral axis > 5 cm). Statistical analysis was performed for normality and significance testing. Results Percutaneous transpedicular spinal instrumentation did not significantly alter any of the spinopelvic parameters in either the ACR group or the non-ACR group. Lateral MI-LIF alone significantly improved coronal Cobb angle by 16°, and the fractional curve significantly improved in a subgroup treated with L5–S1 transforaminal lumbar interbody fusion. Fifteen ACRs were performed in 9 patients and resulted in significant coronal Cobb angle correction, lumbar lordosis correction of 16.5°, and sagittal vertebral axis correction of 4.8 cm per patient. Segmental analysis revealed a 12° gain in segmental lumbar lordosis and a 3.1-cm correction of the sagittal vertebral axis per ACR level treated. Conclusions The lateral MI-LIF with ACR has the ability to powerfully restore lumbar lordosis and correct sagittal imbalance. This segmental MI surgical technique boasts equivalence to SPO correction of these global radiographic parameters while simultaneously creating additional disc height and correcting coronal imbalance. Addition of posterior percutaneous instrumentation without in situ manipulation or overcorrection does not alter radiographic parameters when combined with the lateral MI-LIF.