Timothy R. Kuklo

Minimum 5-year analysis of L5-S1 fusion using sacropelvic fixation (bilateral S1 and iliac screws) for spinal deformity.

Study Design. Clinical radiographic and outcomes investigation. Objective. To investigate clinical and radiographic outcomes for lumbosacral fusion (in patients with spinal deformity) using a combination of bilateral sacral and iliac screws with a minimum 5-year follow-up. Summary of Background Data. To our knowledge, long-term results (>5 years of follow-up) of bilateral S1 screw/bilateral iliac screw fixation have never been published or presented. Materials and Methods. A total of 67 patients (from an initial consecutive cohort of 81) undergoing lumbosacral fusion with bilateral sacral and iliac screws with a minimum follow-up of 5 years (range 5–10 + 5, average 6 + 3) were analyzed for radiographic outcome and clinical course by an outcome questionnaire (administered at ultimate follow-up) analysis. Patients were divided into 2 groups: group 1, 34 patients with mostly high-grade spondylolisthesis; and group 2, 33 with adult scoliosis fused mostly from the thoracic spine to the sacrum. A true anteroposterior pelvis film was obtained in all patients to assess for sacroiliac joint arthritis, as were standard spine radiographs. Patients were administered Oswestry and directed buttock pain questionnaires at latest follow-up. Results. There were no cases of sacral screw failure (i.e., screw loosening, partial screw pullout, or fracture of the sacral screw). There were 5 cases of nonunion at L5–S1. Of the 5 cases, 3 did not have anterior column support at L5–S1. Four of the 5 cases were revised, and, subsequently, 3 achieved union. Iliac screws were removed electively on 1 or both sides in 23 of the patients after 2 years postoperatively because of prominence. There were 7 cases of iliac screw breakage. Iliac screw halos were observed in 29 patients. No sacroiliac osteoarthritis was observed on the true anteroposterior pelvis films. At ultimate follow-up, average visual analog painscale (0–10) score to assess buttock pain was 2.4, and average Oswestry score was 20.1. Conclusions. For high-grade spondylolisthesis and long adult deformity fusions to the sacrum, a montage of bilateral S1 screws and iliac screws were effective in protecting the sacral screws from failure. Pseudarthrosis at L5–S1 was manifested by rod breakage at that level. We saw no evidence of a long-term effect of the iliac screws predisposing the sacroiliac joints to degeneration at follow-up ranging from 5 to 10 years.

Transforaminal lumbar interbody fusion: Clinical and radiographic results and complications in 100 consecutive patients

Objective: We retrospectively reviewed the results of 100 consecutive transforaminal lumbar interbody fusions (TLIFs) performed at one institution. The preoperative diagnoses included degenerative disk disease (55), spondylolisthesis (41; 22 isthmic, 19 degenerative), and degenerative adult scoliosis (4). There were 64 single-level, 33 two-level, 2 three-level, and 1 four-level TLIF (140 levels). Methods: The fusion mass was assessed by an independent observer using biplanar radiography, whereas clinical outcomes were assessed by means of several established outcome measures. Results: By level, the posterolateral fusion was judged to be probably or definitely solid in 78% of levels, whereas the interbody fusion was radiographically solid in 88% of levels, for an overall 93% fusion success/patient (94%/level). All patients had >24 months of postoperative clinical follow-up, and 82 patients (82%) were available for outcome measure assessment at an average follow-up of 34 months (range 24-61 months) postoperatively. Eighty-one percent of these patients reported a >50% decrease in their symptoms, and 76% of patients were satisfied with their results to the degree that they would have the procedure again. However, a large percentage of patients experienced incomplete relief of their symptoms. Twenty patients sustained minor complications, and there were no major complications. Conclusions: We conclude that TLIF is a safe and effective method of achieving lumbar fusion with a 93% radiographic fusion success and a nearly 80% rate of overall patient satisfaction but frequently results in incomplete relief of symptoms. Complications resulting from the procedure are uncommon and generally minor and transient.

Minimum 2-year analysis of sacropelvic fixation and L5-S1 fusion using S1 and iliac screws.

Study Design. An analysis of lumbosacral fusions for high-grade spondylolisthesis fusions with reduction and long fusions to the sacrum in ambulatory adults. Objective. To assess the clinical and radiographic results of lumbosacral fusions using bilateral S1 and iliac screws. Summary of Background Data. S1 screws often fail with lumbosacral fusions, whereas L5–S1 pseudarthrosis is common in patients with deformity. Materials and Methods. A total of 81 patients (38 revision, 43 primary) with minimum 2-year follow-up (average, 4.2 years; range, 2.0–7.1 years) underwent L5–S1 fusion using S1 and iliac screws (158 screws). Forty-nine of 81 constructs (61%) included an anterior load-sharing/fixation device. Group 1 included isthmic spondylolisthesis (n = 42), whereas Group 2 included long fusions (≥3 levels) to the sacrum (n = 39). In Group 2, 15 patients (Group 2A) were fused from L1, L2, or L3 to the sacrum (3–5 levels, average 3.3 levels) and 24 patients (Group 2B) were fused from the thoracic spine to the sacrum (6–17 levels, average 11.5 levels). Twelve patients had pseudarthrosis at L5–S1. A patient questionnaire was completed. Results. A total of 36 of the 38 revision patients had previous iliac crest harvesting, yet iliac screws were placed in 34 of 36 patients. Overall, 78 of 80 patients had iliac crest harvesting (one not attempted). None had loss of screw fixation or iliac crest fracture after harvesting. Four of the 81 patients (4.9%) had pseudarthrosis at L5–S1 after reconstruction. This included solid fusion in 10 of 12 patients presenting with L5–S1 pseudarthrosis. Fourteen percent of patients experienced some discomfort over the iliac screws; however, only one patient required screw removal. Conclusions. Bilateral iliac screws coupled with bilateral S1 screws provide excellent distal fixation for lumbosacral fusions with a high fusion rate (95.1%) in high-grade spondylolisthesis and long fusions to the sacrum. Previous iliac crest harvesting does not prevent ipsilateral screw placement (34 of 36 patients) or additional iliac harvesting (78 of 80 patients).

Accuracy and efficacy of thoracic pedicle screws in curves more than 90

Study Design. Retrospective study of large-magnitude thoracic curves (≥90°) treated with pedicle screw constructs. Objective. To evaluate the results of pedicle screw constructs for thoracic curves ≥ 90° in terms of sagittal and coronal correction/efficacy, as well as accuracy and safety of thoracic pedicle screw placement. Summary of Background Data. Thoracic pedicle screw constructs continue to become increasingly more common; however, the debate continues about the safety and efficacy of these constructs because of their perceived increased risk of neurologic injury and the increased cost of spinal instrumentation. Methods. Since 1998, all patients with adolescent idiopathic scoliosis, or adult progression of adolescent idiopathic scoliosis, a thoracic curve ≥ 90° and a minimum 2-year follow-up who were treated with pedicle screw constructs were included in this study. Standing anteroposterior (or posteroanterior), lateral and bending preoperative radiographs, and anteroposterior (or posteroanterior) and lateral postoperative radiographs were evaluated for curve magnitude, flexibility, and postoperative correction to assess the efficacy of these constructs in the immediate postoperative period and at latest follow-up. Postoperative CT scans were evaluated for screw accuracy using established 2-mm increments (intrapedicular, 0–2 mm breach, 2–4 mm breach, > 4 mm breach). Preoperative plans were also reviewed to evaluate the ability to place a pedicle screw at each planned level in these large-magnitude curves. Results. Twenty patients with thoracic curves ≥ 90° and an average follow-up of 3.3 years (range, 2.0–5.2 years) were included in the study. All patients underwent a posterior spinal fusion with a pedicle screw only construct. The average preoperative main thoracic curve measured 100.2° (range, 90°–133°), with an average side-bender of 71.6° (29% flexibility). The average postoperative main thoracic curve was 32.3° (68% correction). A total of 352 thoracic screws were placed in the 20 cases (17.6 screws/case). Screw accuracy (either intrapedicular or <2 mm breach) was 96.3% (339 of 352 screws) by postoperative CT scanning. Ten screws were considered to have a breach between 2 and 4 mm (3 medial, 7 lateral), while three screws were > 4 mm (2 medial, 1 lateral). The two medial screws were the only placed screws that were removed (0.57%). Overall, 94% of planned screws (352 of 374 screws) were placed according to the preoperative plan. There were no incidences of screw or instrumentation failure. Of note, there was a temporary decrease in motor-evoked potentials during curve correction in 2 cases; however, there were no identifiable neurologic complications. Conclusions. Thoracic pedicle screw constructs can be safely used for large-magnitude curves. Curve correction (68%) is powerful for these curves, which are stiff and difficult to manage. Correction should be performed carefully with consideration given to convex compression for cases with concomitant hyperkyphosis for these “at risk” spinal cords. Screw accuracy (96.3%) was excellent in this review. The authors found that screws can consistently be placed according to the preoperative plan even in these large-magnitude curves.

Intervertebral Disc Tissue Engineering Using a Novel Hyaluronic Acid–Nanofibrous Scaffold (HANFS) Amalgam

Degeneration of the intervertebral disc (IVD) represents a significant musculoskeletal disease burden. Although spinal fusion has some efficacy in pain management, spine biomechanics is ultimately compromised. In addition, there is inherent limitation of hardware-based IVD replacement prostheses, which underscores the importance of biological approaches to disc repair. In this study, we have seeded multipotent, adult human mesenchymal stem cells (MSCs) into a novel biomaterial amalgam to develop a biphasic construct that consisted of electrospun, biodegradable nanofibrous scaffold (NFS) enveloping a hyaluronic acid (HA) hydrogel center. The seeded MSCs were induced to undergo chondrogenesis in vitro in the presence of transforming growth factor-beta for up to 28 days. The cartilaginous hyaluronic acid-nanofibrous scaffold (HANFS) construct architecturally resembled a native IVD, with an outer annulus fibrosus-like region and inner nucleus pulposus-like region. Histological and biochemical analyses, immunohistochemistry, and gene expression profiling revealed the time-dependent development of chondrocytic phenotype of the seeded cells. The cells also maintain the microarchitecture of a native IVD. Taken together, these findings suggest the prototypic potential of MSC-seeded HANFS constructs for the tissue engineering of biological replacements of degenerated IVD.

Straight-Forward Versus Anatomic Trajectory Technique of Thoracic Pedicle Screw Fixation : A Biomechanical Analysis

Study Design. A biomechanical study on cadaveric thoracic vertebrae using pullout strength, insertional torque, and bone mineral density to determine the optimal sagittal trajectory of thoracic pedicle screws. Objective. To perform a biomechanical study on cadaveric thoracic vertebrae using insertional torque, pullout strength, and bone mineral density to determine the optimal biomechanical sagittal trajectory for placement thoracic pedicle screws. We compared the straight-forward (paralleling the vertebral endplate) with anatomic trajectory (directed along the true anatomic axis of the pedicle). Methods. Thirty cadaveric thoracic vertebrae were harvested and evaluated with dual-energy x-ray absorptiometry to assess bone mineral density. Matched, fixed-head pedicle screws were then randomly assigned by side and placed using the straight-forward or anatomic technique under fluoroscopic visualization while recording the maximum insertional torque. Pullout strength testing was then performed. Results. The maximum insertional torque for the straight-forward technique was 2.58 ± 0.14 (SE) in pounds, whereas the anatomic technique averaged 1.86 ± 0.14 (SE) in pounds (P = 0.0005). The maximum insertional torque at the neurocentral junction for the straight-forward technique averaged 1.89 ± 0.17 (SE) in-lbs. (73% of maximum insertional torque), whereas the anatomic trajectory averaged 1.39 ± 0.11 (SE) in pounds (75% of maximum insertional torque) (P = 0.007). The average pullout strength using a straight-forward trajectory was 611 ± 50 (SE) N compared to the anatomic trajectory, which averaged 481 ± 54 (SE) N (P = 0.034). The pullout strength correlated with mean bone mineral density for both the straight-forward (r = 0.461, P = 0.027) and anatomic (r = 0.598, P = 0.004) techniques. Conclusions. The straight-forward technique results in a 39% increase in maximum insertional torque and a 27% increase in pullout strength compared to the anatomic technique. The maximum insertional torque at the neurocentral junction resulted in a 36% increase using the straight-forward technique versus the anatomic trajectory. Bone mineral density directly correlates with pullout strength for both techniques.

Radiographic Outcomes of Anterior Spinal Fusion Versus Posterior Spinal Fusion With Thoracic Pedicle Screws for Treatment of Lenke Type I Adolescent Idiopathic Scoliosis Curves

Study Design. Analysis of radiographic outcomes following surgical correction of scoliosis. Objectives. To compare the curve correction and derotation following anterior spinal fusion (ASF) versus posterior spinal fusion (PSF) with thoracic pedicle screws. Summary of Background Data. The benefits of ASF in adolescent idiopathic scoliosis include saving distal fusion levels and historically greater correction and derotation compared with PSF. However, comparative studies between ASF and PSF have generally consisted only of posterior hook instrumentation or hybrid constructs, with no direct comparisons between anterior fusion and thoracic pedicle screw (TPS) series. Methods. We performed a retrospective review of the radiographic and medical records of 40 patients (two curve-matched groups) with Lenke Type I main thoracic adolescent idiopathic scoliosis. There were 20 patients who underwent open ASF with single-rod instrumentation with a mean age at surgery of 15 years + 6 months (range, 12–20 years) and 20 patients who underwent PSF with TPS constructs with a mean age at surgery of 13 + 6 (range, 12–15). Radiographic follow-up averaged 44.1 month (24–80) for the ASF group and 55.1 month (25–83) for the PSF/TPS group. We evaluated the sagittal alignment, Cobb angles, rib hump deformity (RH), apical rib spread difference (ARSD), and apical vertebral body-rib ratio (AVB-R), measures of rotation and thoracic torsion, between both groups. Results. Before surgery, the main thoracic curve was 55.1° (range, 47–66°) for the ASF group and 52.5° (range, 46–68°) for the PSF/TPS group (P = 0.16). Additionally, there was no difference in the pelvic tilt curves, thoracic kyphosis, lumbar lordosis, RH, or ARSD. However, there was a slightly greater preoperative thoracolumbar-lumbar (TL/L) curve (34.6° versus 29.5°, P = 0.04) and AVB-R (1.75 versus 1.5, P = 0.003) in the ASF group. After surgery, an average of 6.5 levels (range, 6–8) were fused in the ASF group, compared with 7.7 levels (range, 5–12) in the PSF/TPS group (P = 0.001) or 1.2 additional levels for PSF/TPS. At final postoperative follow-up, spontaneous pelvic tilt curve correction was greater in the ASF group (47% versus 35%), although this difference did not reach statistical significance (P = 0.07). For the main thoracic and TL/L curves, there was greater correction in the PSF/TPS group (62% versus 52%, P = 0.009; and 56% versus 41%, P = 0.03), respectively. Additionally, the PSF/TPS group demonstrated significantly greater RH correction (51% versus 26%, P = 0.005) and AVB-R ratio improvement (73% versus 32%, P < 0.0001). We also noted a trend towards increased correction of the ARSD in the PSF/TPS group (58% versus 32%, P = 0.07). Further, the postoperative thoracic kyphosis decreased 4.4° in the PSF/TPS group (postop avg. 25.0°) and increased 5.7° (average, 30.6°) in the ASF group (P = 0.04). Conclusions. In this curve-matched cohort of Lenke Type I curves, PSF with TPS provided superior instrumented correction of main thoracic curves and spontaneous correction of TL/L curves. Perhaps more importantly, PSF/TPS demonstrated improved correction of thoracic torsion and rotation as compared with ASF in terms of RH (P = 0.005) and AVB-R ratio (P= 0.0001), with only one additional spinal segment fused on average.

Measurement of Thoracic and Lumbar Fracture Kyphosis : Evaluation of Intraobserver, Interobserver, and Technique Variability

Study Design. Statistical analysis of various measurement techniques for thoracolumbar burst fracture kyphosis on lateral radiograph. Objective. To determine the most reliable measurement technique. Summary of Background Data. The treatment of thoracic and lumbar burst fractures involves many factors, including the degree of resultant kyphosis. Although various methods have been described, no study has directly compared these methods for reliability and reproducibility. Methods. Fifty lateral radiographs of thoracic and lumbar burst fractures were randomly selected and measured on two separate occasions by three spine surgeons using five different measurement techniques. Radiograph quality, fracture type, and the center beam location were determined. Statistical analysis included analysis of variance for repeated measures and analysis of variance using a generalized linear model. Results. Intraclass correlation coefficients were most consistent for Method 1 (rho = 0.83–0.94) followed by Method 4 (rho = 0.65–0.89) and Method 5 (rho = 0.73–0.85). Intraobserver agreement (% of repeated measures within 5° of the original measurement) ranged between 72% and 98% for all techniques for all three observers, with Method 1 showing the best agreement (84%–98%). Paired comparisons between observers varied considerably with interobserver reliability correlation coefficients ranging from 0.52 to 0.93. Method 1 showed the highest interobserver reliability coefficient (0.81, range 0.71–0.93) followed by Method 5 (0.71, range 0.68–0.75). Method 1 also had the highest percentage of agreement within categories (90% within 5°). Conclusions. Method 1 (measuring from the superior endplate of the vertebral body one level above the injured vertebral body to the inferior endplate of the vertebral body one level below) showed the best intraobserver and interobserver reliability overall.

Correlation of Radiographic, Clinical, and Patient Assessment of Shoulder Balance Following Fusion Versus Nonfusion of the Proximal Thoracic Curve in Adolescent Idiopathic Scoliosis

Study Design. Retrospective clinical, radiographic, and patient outcome review of surgically treated adolescent idiopathic scoliosis. Objectives. To correlate radiographic and clinical features of shoulder balance and the proximal thoracic curve with patient satisfaction outcomes at a minimum 2-year follow-up. Summary of Background Data. Traditionally, radiographic features of a structural proximal thoracic curve have been T1 tilt, proximal thoracic Cobb angle, and proximal thoracic side-bending Cobb; however, these do not always correlate with clinical shoulder balance. Methods. A total of 112 patients (single surgeon) with adolescent idiopathic scoliosis and a proximal thoracic curve ≥20° (average 32°, range 20–78°) were evaluated in terms of shoulder balance and curve flexibility/correction. Four groups were analyzed: Group 1, posterior spinal fusion to T2 (proximal thoracic curve included, n = 24); Group 2, posterior spinal fusion to T3 (proximal thoracic curve partially included, n = 23); Group 3, posterior spinal fusion to T4 or T5 (proximal thoracic curve not included, n = 21); and Group 4, anterior spinal fusion to T4 or below (proximal thoracic not included, n = 44). Proximal thoracic, main thoracic, and thoracolumbar-lumbar upright coronal, side-bending, and sagittal Cobb measurements were assessed before surgery, 1 week after surgery, and at a minimum 2-year postoperative follow-up (average 3.8 years, range 2.0–7.6 years). In addition to T1 tilt, clavicle angle (intersection of a horizontal line and the tangential line connecting the highest two points of each clavicle), coracoid height difference, trapezius length (horizontal distance of the T2 pedicle to second rib–clavicle intersection), first rib–clavicle height difference (vertical distance of first rib apex to superior clavicle), and proximal thoracic, main thoracic, and thoracolumbar-lumbar apical vertical translation were determined. Shoulder asymmetry as measured by the radiographic soft tissue shadow was graded as balanced (<1 cm), slight (1–2 cm), moderate (2–3 cm), or significant (>3 cm). A postoperative patient questionnaire addressed shoulder balance and overall appearance at most recent follow-up. Results. The four groups were found to be statistically equivalent in terms of preoperative proximal thoracic curve (P = 0.4146), proximal thoracic side-bending Cobb (P = 0.2199), main thoracic curve (P = 0.6999), and main thoracic side-bending curves (P = 0.7307). Radiographic: Preoperative proximal thoracic measurements correlating with postoperative shoulder balance (P < 0.05) included the clavicle angle (three of four groups with a trend toward statistical significance in the fourth group, P = 0.07) and coracoid height (two of four groups). No other measurement, including T1 tilt and proximal thoracic side-bending Cobb, correlated in more than one group. Proximal thoracic curve correction was greatest in Group 1 (posterior spinal fusion to T2; average 12°) and Group 4 (anterior spinal fusion to T4 or below; average 12°). Clinical: Shoulder balance improved in all four groups (range 0.38–1.00 grades). There was no difference in shoulder balance between groups (P = 0.2723). Patient assessment: All four groups also reported improvement in self-perceived shoulder balance (63% up to one grade, 37% over two-grade improvement), whereas no patient reported worsening of shoulder balance. There was no significant difference in patient outcomes between the four groups (P = 0.3654). Conclusion. The clavicle angle, not T1 tilt, upright proximal thoracic, or side-bending proximal thoracic Cobb, provided the best preoperative radiographic prediction of postoperative shoulder balance. In each of the four groups, postoperative shoulder balance and clinical appearance also improved and correlated with patient postoperative assessments.

Surgical Revision Rates of Hooks versus Hybrid versus Screws versus Combined Anteroposterior Spinal Fusion for Adolescent Idiopathic Scoliosis

Study Design. Multi-institution retrospective review. Objective. To determine the surgical revision rates of hook, hybrid, anteroposterior, and total pedicle screw constructs for adolescent idiopathic scoliosis (AIS). Summary of Background Data. Much debate continues on the safety, efficacy, and cost of thoracic pedicle screws. Nonetheless, there are no large series that have evaluated the revision rate of various constructs in AIS to determine the need for repeat surgery, and therefore, the added indirect costs and risks of additional procedures. Methods. We retrospectively reviewed the surgical case logs of 1428 patients with AIS at 2 institutions from 1990 to 2004, and the clinical records and radiographs of revision cases. Patients were classified into 1 of 4 groups: hook, hybrid hook and screw, all pedicle screw, and combined anteroposterior fusion constructs. Overall, there were 65 (4.6%) returns to the operating room, or 55 (3.9%) cases after excluding infections without concomitant pseudarthrosis. Results. Of the 65 revision cases, there were 52 females and 13 males, at an average age at first surgery of 13.9 years (range, 9–18 years), and an average age at revision of 14.7 years (range, 12–23 years). For the revision cases, the average initial Cobb was 61.9° (range 44°–110°), and this was not statistically different within the cohorts (P > 0.05). In terms of revision rate, all hook constructs had a higher revision rate secondary to instrumentation failure when compared with screws, while both hook and hybrid constructs had an overall higher surgical revision rate when compared with screw constructs or anteroposterior constructs (all P ≤ 0.05). The pseudarthrosis rate trended toward, but did not meet, statistical significance between these same groups. Conclusion. All pedicle screw and anteroposterior constructs have a lower surgical revision rate when compared with hook and hybrid constructs. The hidden patient and financial costs of these findings should be considered when evaluating overall instrumentation efficacy.