Lawrence G. Lenke

Monaxial versus multiaxial thoracic pedicle screws in the correction of adolescent idiopathic scoliosis

Study Design. Radiographic outcome analysis following thoracic fusion of Lenke Type I adolescent idiopathic scoliosis (AIS) curves with segmental pedicle screw fixation. Objective. To compare the correctional capacity of monaxial versus multiaxial pedicle screws in a matched cohort of AIS patients. Summary of Background Data. Thoracic pedicle screws provide improved curve correction over hook and wire or hybrid constructs for AIS. Further, both monaxial and multiaxial screws are available, with each offering certain advantages over the other. However, different screw types have not been evaluated against each other. Methods. We retrospectively reviewed the preoperative and final postoperative follow-up radiographs of an age- and curve-matched cohort of 35 consecutive Lenke Type I AIS patients. Fifteen were treated with monaxial and 20 were treated with multiaxial pedicle screw constructs. All patients had a minimum 2-year follow-up. The average age at surgery was 14 years 4 months (range, 12–17 years) in the monaxial group and 13 years 8 months (12–16 years) in the multiaxial group. Evaluation included coronal proximal thoracic (PT), main thoracic (MT), and thoracolumbar/lumbar (TL/L) Cobb angles and flexibility indexes, regional sagittal curvature, the sagittal apical rib hump (RH) deformity, the apical vertebral body-rib ratio (AVB-R: ratio of linear measures from left and right apical body to lateral rib), and the apical rib spread distance (ARSD, difference of the sums of the intercostal distances at the five periapical segments measured at the lateral transverse process). Results. There was no statistically significant difference with regard to the preoperative PT curves, MT curves, TL/L curves, flexibility indexes, regional sagittal curvature, AVB-R, or ARSD. The preoperative rib humps were significantly greater in the monaxial screw group (42.4 mm vs. 34.7 mm; P = 0.02). Postoperative follow-up averaged 59.9 months (range, 24–98 months) for the monaxial group and 38.0 months (range, 24–55 months) for the multiaxial group (P < 0.0001). An average of 7.7 vertebral levels were fused in the monaxial group compared with 7.2 levels in the multiaxial group (P = 0.39). After surgery, both constructs provided excellent instrumented correction of the MT curves (64.9% vs. 60.0% for the monaxial and multiaxial groups, respectively; P = 0.33), as well as good spontaneous correction of the PT (41.3% vs. 40.5%; P = 0.92) and TL/L curves (55.4% vs. 51.7%; P = 0.66). Monaxial screws demonstrated significantly greater absolute (13.9 mm vs. 25.2 mm; P < 0.0001) and relative (66.1% vs. 24.7%; P < 0.0001) correction of the apical RH. Additionally, AVB-R (77.9% vs. 54.1%; P = 0.0007) and ARSD (82.8% vs. 69.9%; P = 0.04) corrections were significantly greater in the monaxial group. There were no neurologic deficits or major complications in either group. Conclusion. Both monaxial and multiaxial thoracic pedicle screws provide excellent coronal deformity correction for thoracic fusion of main thoracic AIS. Monaxial screws provide superior derotation and restoration of thoracic symmetry as noted by significantly greater correction of the AVB-R, RH, and ARSD.

Optimal surgical care for adolescent idiopathic scoliosis: an international consensus.

AbstractPurposenThe surgical management of adolescent idiopathic scoliosis (AIS) has seen many developments in the last two decades. Little high-level evidence is available to support these changes and guide treatment. This study aimed to identify optimal operative care for adolescents with AIS curves between 40° and 90° Cobb angle.MethodsFrom July 2012 to April 2013, the AOSpine Knowledge Forum Deformity performed a modified Delphi survey where current expert opinion from 48 experienced deformity surgeons, representing 29 diverse countries, was gathered. Four rounds were performed: three web-based surveys and a final face-to-face meeting. Consensus was achieved with ≥70xa0% agreement. Data were analyzed qualitatively and quantitatively.ResultsConsensus of what constitutes optimal care was reached on greater than 60 aspects including: preoperative radiographs; posterior as opposed to anterior (endoscopic) surgical approaches; use of intraoperative spinal cord monitoring; use of local autologous bone (not iliac crest) for grafts; use of thoracic and lumbar pedicle screws; use of titanium anchor points; implant density of <80xa0% for 40°–70° curves; and aspects of postoperative care. Variability in practice patterns was found where there was no consensus. In addition, there was consensus on what does not constitute optimal care, including: routine pre- and intraoperative traction; routine anterior release; use of bone morphogenetic proteins; and routine postoperative CT scanning.ConclusionsInternational consensus was found on many aspects of what does and does not constitute optimal operative care for adolescents with AIS. In the absence of current high-level evidence, at present, these expert opinion findings will aid health care providers worldwide define appropriate care in their regions. Areas with no consensus provide excellent insight and priorities for future research.

Evaluation of complications and neurological deficits with three-column spine reconstructions for complex spinal deformity: a retrospective Scoli-RISK-1 study

OBJECTnThe goal in this study was to evaluate the risk factors for complications, including new neurological deficits, in the largest cohort of patients with adult spinal deformity to date.nnnMETHODSnThe Scoli-RISK-1 inclusion criteria were used to identify eligible patients from 5 centers who were treated between June 1, 2009, and June 1, 2011. Records were reviewed for patient demographic information, surgical data, and reports of perioperative complications. Neurological deficits were recorded as preexisting or as new deficits. Patients who underwent 3-column osteotomies (3COs) were compared with those who did not (posterior spinal fusion [PSF]). Between-group comparisons were performed using independent samples t-tests and chi-square analyses.nnnRESULTSnTwo hundred seven patients were identified-75 who underwent PSF and 132 treated with 3CO. In the latter group, patients were older (58.9 vs 49.4 years, p < 0.001), had a higher body mass index (29.0 vs 25.8, p = 0.029), smaller preoperative coronal Cobb measurements (33.8° vs 56.4°, p < 0.001), more preoperative sagittal malalignment (11.7 cm vs 5.4 cm, p < 0.001), and similar sagittal Cobb measurements (45.8° vs 57.7°, p = 0.113). Operating times were similar (393 vs 423 minutes, p = 0.130), although patients in the 3CO group sustained higher estimated blood loss (2120 vs 1700 ml, p = 0.066). Rates of new neurological deficits were similar (PSF: 6.7% vs 3CO: 9.9%, p = 0.389), and rates of any perioperative medical complication were similar (PSF: 46.7% vs 3CO: 50.8%, p = 0.571). Patients who underwent vertebral column resection (VCR) were more likely to sustain medical complications than those treated with pedicle subtraction osteotomy (73.7% vs 46.9%, p = 0.031), although new neurological deficits were similar (15.8% vs 8.8%, p = 0.348). Regression analysis did not reveal significant predictors of neurological injury or complication from collected data.nnnCONCLUSIONSnDespite higher estimated blood loss, rates of all complications (49.3%) and new neurological deficits (8.7%) did not vary for patients who underwent complex reconstruction, whether or not a 3CO was performed. Patients who underwent VCR sustained more medical complications without an increase in new neurological deficits. Prospective studies of patient factors, provider factors, and refined surgical data are needed to define and optimize risk factors for complication and neurological deficits.

Free-Hand Pedicle Screw Placement During Revision Spinal Surgery : Analysis of 552 Screws

Study Design. A retrospective study. Objective. To evaluate the safety of free-hand pedicle screw placement during revision surgery at levels with a solid posterior fusion mass and/or identified pseudarthroses of the thoracic and lumbosacral spine. Summary of Background Data. Placement of pedicle screws into previous fusion masses or pseudarthrosis levels of the spine is challenging because of the loss of anatomic landmarks. We are aware of no study focusing on screw placement without any type of radiographic or navigational assistance. Methods. Thirty-seven patients underwent revision spinal surgery with posterior spinal instrumentation and fusion using 552 transpedicular screws by a single surgeon from 1994 to 2003. Among 552 screws, 184 were inserted into virgin levels, 60 were inserted into the vertebral body through previous screw holes, 208 were inserted into fusion masses, and 100 were inserted into pseudarthrosis levels. We used the quadrangulation method to gain pedicle access in a prior fusion mass after diligent exposure of any and all visible anatomic landmarks. All screws were analyzed using radiographs, intraoperative monitoring data, and clinical outcomes. Results. There were 29 women and 8 men. The mean age of patients at the time of surgery was 38 + 6 years (range, 8–75 years). Six screws were removed intraoperatively according to the triggered electromyography criteria and 4 of them were repositioned after checking the integrity of the pedicle by a careful probing technique (1.09%). Six screws were removed after checking the intraoperative radiographs and 5 screws were misplaced, as noted, in postoperative radiographs (1.99%). Two patients underwent revision surgery at 3 days and 6 weeks after initial surgery, respectively, for root decompression at the osteotomy site although screw positions were correct. Conclusion. The free-hand technique of thoracic and lumbosacral pedicle screw placement in revision spinalsurgery is reliable and safe when using the quadrangulation method of gaining pedicle access in a prior fusion mass or at pseudarthrosis levels.

Neurologic Outcomes of Complex Adult Spinal Deformity Surgery: Results of the Prospective, Multicenter Scoli-RISK-1 Study.

Study Design. Prospective, multicenter, international observational study. Objective. To evaluate motor neurologic outcomes in patients undergoing surgery for complex adult spinal deformity (ASD). Summary of Background Data. The neurologic outcomes after surgical correction for ASD have been reported with significant variability and have not been measured as a primary endpoint in any prospective, multicenter, observational study. Methods. The primary outcome measure was the change in American Spinal Injury Association (ASIA) Lower Extremity Motor Scores (LEMS) obtained preoperatively, and at hospital discharge, 6 weeks and 6 months postoperatively. Results. A total of 273 patients with complex ASD underwent surgery at 15 sites worldwide. One patient was excluded for lack of preoperative LEMS. The remaining 272 patients were divided into two groups: normal preoperative LEMS (=50) (Preop NML, Nu200a=u200a204, 75%) and abnormal preoperative LEMS (<50) (Preop ABNML, Nu200a=u200a68, 25%). At hospital discharge, 22.18% of patients showed a decline in LEMS compared with 12.78% who showed an improvement. At 6 weeks, there was a significant change compared with discharge: 17.91% patients showed a decline in LEMS and 16.42% showed an improvement. At 6 months, 10.82% patients showed a decline in preoperative LEMS, 20.52% improvement, and 68.66% maintenance. This was a significant change compared with 6 weeks and at discharge. Conclusion. Although complex ASD surgery can restore neurologic function in patients with a preoperative neurologic deficit, a significant portion of patients with ASD experienced postoperative decline in LEMS. Measures that can anticipate and reduce the risk of postoperative neurologic complications are warranted. Level of Evidence: 3

Anterior thoracic scoliosis constructs: effect of rod diameter and intervertebral cages on multi-segmental construct stability

BACKGROUND CONTEXTnMany studies have reported on the use of anterior instrumentation for thoracolumbar scoliosis and more recently thoracic scoliosis. However, the optimal construct design remains an issue of debate.nnnPURPOSEnTo optimize construct design and enhance implant survival until a successful spinal arthrodesis is achieved.nnnSTUDY DESIGNnThis study evaluated the effect of rod diameter and intervertebral cages on construct stiffness and rod strain using a long-segment, anterior thoracic scoliosis model with varying levels of intervertebral reconstruction.nnnMETHODSnSixteen fresh-frozen calf spine specimens (T1 to L1) were divided into two groups based on rod diameter reconstruction (4 mm and 5 mm). Testing included axial compression, anterior flexion, extension and lateral bending with variations in the number and level of intervertebral cage reconstructions: apical disc (one), end discs (two), apical and end discs (three), all seven levels (seven). Multisegmental construct stiffness and rod strain were determined and normalized to the intact specimen for analysis.nnnRESULTSnThe seven-level intervertebral cage construct showed significantly greater stiffness in axial compression for both the 4-mm (366% increased stiffness) and 5-mm (607% increased stiffness) rod groups (p<.001). The remaining constructs were not significantly different from each other (p>.05). In flexion, similar results were obtained for the 4-mm construct (p<.001) but not the 5-mm construct, because the reconstruction-alone, one-, two- and three-cage constructs were all significantly stiffer than the intact specimen (p<.05). Multisegmental construct stiffness under extension loading, as well as right and left lateral bending, also exhibited significant differences between the seven-level interbody cage reconstructions and the remaining constructs. Apical rod strain for both the 4-mm-rod and 5-mm-rod groups were significantly higher for the two cage constructs (a cage at either end but not the apex where the strain gauges were located) as compared with the other constructs (p<.05). These differences were more pronounced in the 4-mm-rod group. Similar results were obtained in anterior flexion, extension and lateral bending.nnnCONCLUSIONSnIntervertebral cages at every level significantly improved construct stiffness compared with increasing rod diameter alone. Moreover, cages markedly decreased rod strain, and when structural interbody supports were not used, axial compression created the greatest rod strain.

Failure of Intraoperative Monitoring to Detect Postoperative Neurologic Deficits: A 25-year Experience in 12,375 Spinal Surgeries

Study Design. Retrospective. Objective. The purpose was to categorize and evaluate intraoperative monitoring (IOM) failure to detect neurologic deficits occurring during spinal surgery. Summary of Background Data. The efficacy of spinal cord/nerve root monitoring regarding undetected neurologic deficits is examined in a large, single institution series involving all levels of the spinal column and all spinal surgical procedures. Methods. Multimodality IOM included somatosensory-evoked potentials (SSEPs), descending neurogenic-evoked potentials (DNEPs), transcranial motor-evoked potentials (MEPs), dermatomal somatosensory-evoked potentials (DSEPs), and spontaneous and triggered electromyography (spEMG, trgEMG). We reviewed 12,375 patients who underwent surgery for spinal pathology from 1985 to 2010. There were 7178 females (59.3%) and 5197 males (40.7%); 9633 (77.8%) primary surgeries and 2742 (22.2%) revisions. Procedures by spinal level were cervical 29.7% (3671), thoracic/thoracolumbar 45.4% (5624), and lumbosacral 24.9% (3080). Age at surgery was >u200a18 years - 72.7% (8993) and <u200a18 years - 27.3% (3382). Results. Forty-five of the 12,375 patients (0.36%) had false negative outcomes. False negative results by modality were as follows: spEMG (nu200a=u200a22, 48.8%), trgEMG (nu200a=u200a8, 17.7%), DSEP (nu200a=u200a4, 8.8%), DNEP (nu200a=u200a4, 8.8%), SSEP (nu200a=u200a3, 6.6%), DSEP/spEMG (nu200a=u200a3, 6.6%), and trgEMG/spEMG (nu200a=u200a1, 2.2%). Thirty-seven patients had immediate postoperative deficits unidentified by IOM; 30 patients (81%) involved nerve root monitoring, four patients had spinal cord deficits, and three patients had peripheral sensory deficits. Eight patients had permanent neurologic deficits, six (0.048%) were nerve root and two (0.016%) were spinal cord in nature. Conclusion. Despite correct application and usage, IOM data failed to identify 45 (0.36%) patients with false negative outcomes out of 12,375 surgical patients. Eight patients (0.064%) of these 45 patients had permanent neurologic deficits, six patients had nerve root deficits in nature and two patients had spinal cord deficits. Although admittedly small, this represents the risk of undetected neurologic deficits even when properly using IOM. Deficits are at a higher risk to remain unresolved when not detected by IOM. Level of Evidence: 4

Recent and Emerging Advances in Spinal Deformity

BACKGROUNDnOver the last several decades, significant advances have occurred in the assessment and management of spinal deformity.nnnOBJECTIVEnThe primary focus of this narrative review is on recent advances in adult thoracic, thoracolumbar, and lumbar deformities, with additional discussions of advances in cervical deformity and pediatric deformity.nnnMETHODSnA review of recent literature was conducted.nnnRESULTSnAdvances in adult thoracic, thoracolumbar, and lumbar deformities reviewed include the growing applications of stereoradiography, development of new radiographic measures and improved understanding of radiographic alignment objectives, increasingly sophisticated tools for radiographic analysis, strategies to reduce the occurrence of common complications, and advances in minimally invasive techniques. In addition, discussion is provided on the rapidly advancing applications of predictive analytics and outcomes assessments that are intended to improve the ability to predict risk and outcomes. Advances in the rapidly evolving field of cervical deformity focus on better understanding of how cervical alignment is impacted by thoracolumbar regional alignment and global alignment and how this can affect surgical planning. Discussion is also provided on initial progress toward development of a comprehensive cervical deformity classification system. Pediatric deformity assessment has been substantially improved with low radiation-based 3-D imaging, and promising clinical outcomes data are beginning to emerge on the use of growth-friendly implants.nnnCONCLUSIONnIt is ultimately through the reviewed and other recent and ongoing advances that care for patients with spinal deformity will continue to evolve, enabling better informed treatment decisions, more meaningful patient counseling, reduced complications, and achievement of desired clinical outcomes.

Preoperative Bracing Affects Postoperative Outcome of Posterior Spine Fusion With Instrumentation for Adolescent Idiopathic Scoliosis

Study Design. Multicenter, prospective clinical series. Objective. To investigate the effect of preoperative bracing on postoperative outcome of posterior spine fusion with instrumentation for adolescent idiopathic scoliosis. Summary of Background Data. Bracing is the standard of care for adolescent idiopathic scoliosis between 25° and 45°, yet the efficacy of bracing is questionable. It is important to evaluate the effect of bracing on outcomes in the adolescent idiopathic scoliosis population. Methods. We reviewed the outcomes of 281 before surgery braced and 328 before surgery nonbraced patients who underwent posterior spine fusion with instrumentation for adolescent idiopathic scoliosis before operation and at 2 years after operation using the Scoliosis Research Society instrument (SRS-30) and the Spinal Appearance Questionnaire. Results. At 2 years after operation, nonbraced patients demonstrated a greater improvement in the SRS-30 Pain domain score (0.23 vs. 0.08, P < 0.001), more improvement in back pain at rest (26.7% vs. 20.5%, P = 0.0009), and more improvement in back pain in the past 6 months (42.4% vs. 32.6%, P = 0.039) compared to braced patients. Also at 2 years after operation, nonbraced patients reported higher SRS-30 Activity domain scores (4.38 vs. 4.32, P = 0.031), Satisfaction domain scores (4.53 vs. 4.42, P = 0.007), and Total scores (4.27 vs. 4.35, P = 0.036) compared with braced patients. The 2-year Spinal Appearance Questionnaire scores showed that nonbraced patients reported a greater “decrease in importance” than braced patients in having “more even shoulders” (79.4% vs. 70.5%, P = 0.03), “more even hips” (74.6% vs. 71.6%, P = 0.042), and “more even ribs in back” (78.4% vs. 69.5%, P = 0.05). Conclusion. Before surgery braced patients have more pain, lower activity levels, lower satisfaction, and lower total SRS-30 scores at 2 years after operation. Braced patients also have more “spine-specific” appearance concerns compared to nonbraced patients. These results suggest a negative impact of preoperative bracing on outcomes after posterior spinal fusion for adolescent idiopathic scoliosis. This “brace signature” should be taken into account when brace treatment is being considered.

Preoperative Halo-Gravity Traction for Severe Pediatric Spinal Deformity: Complications, Radiographic Correction and Changes in Pulmonary Function

BACKGROUND SUMMARYnThe use of preoperative halo-gravity traction (HGT) improves both spinal deformity and pulmonary function and is a helpful adjuvant in the treatment of complex spinal deformity. Despite the benefits of preoperative HGT, there is no consensus on the optimal traction protocol.nnnMETHODSnWe evaluated the treatment of 33 patients treated with preoperative HGT to determine the safety and efficacy of preoperative HGT with regards to deformity correction; to quantify changes in pulmonary function; and to better define an ideal preoperative traction protocol. All patients were treated at the same tertiary-care pediatric hospital between 1998 and 2007. Inclusion criteria were preoperative HGT (before anterior and/or posterior spinal fusion), pretraction spinal Radiographs, repeat Radiographs taken during the traction period, and repeat Radiographs taken at the completion of traction and final Radiographs after surgical correction. The average duration of preoperative HGT was 70.1 days. The average traction weight applied was 38.5% of total body weight. Maximal traction weight was achieved in an average of 30.5 days.nnnRESULTSnOur results, 35% correction of the coronal Cobb and 35% correction of the sagittal Cobb, are consistent with others reported in the literature. Pulmonary function tests taken before and after traction were available for 22 patients. Treatment with HGT improved pulmonary function results in 19xa0patients. There were no serious complications.nnnCONCLUSIONnWe found that preoperative HGT is a safe and useful adjuvant to the treatment of patients with severe scoliosis. Significant deformity correction averaging 35% percent can be expected, with the majority of deformity correction occurring after 3 to 4 weeks. In the majority of patients, this correction is maintained or even improved with subsequent surgical correction.