Anthony Rinella

Proximal junctional kyphosis in adult spinal deformity following long instrumented posterior spinal fusion : Incidence, outcomes, and risk factor analysis

Study Design. To analyze patient outcomes and risk factors associated with proximal junctional kyphosis (PJK) in adults undergoing long posterior spinal fusion. Objectives. To determine the incidence of PJK and its effect on patient outcomes and to identify any risk factors associated with developing PJK. Summary of Background Data. The incidence of PJK and its affect on outcomes in adult deformity patients is unknown. No study has concentrated on outcomes of patients with PJK. Risk factors for developing PJK are unknown. Methods. Radiographic data on 81 consecutive adult deformity patients with minimum 2-year follow-up (average 5.3 years, range 2–16 years) treated with long instrumented segmental posterior spinal fusion was collected. Preoperative diagnosis was adult scoliosis, sagittal imbalance or both. Radiographic measurements analyzed included the sagittal Cobb angle at the proximal junction on preoperative, early postoperative, and final follow-up standing long cassette radiographs. Additional measurements used for analysis included the C7-Sacrum sagittal plumb and the T5–T12 sagittal Cobb. Postoperative SRS-24 scores were available on 73 patients. Results. Incidence of PJK as defined was 26%. Patients with PJK did not have lower outcomes scores. PJK did not produce a more positive sagittal C7 plumb. PJK was more common at T3 in the upper thoracic spine. Conclusions. Incidence of proximal junctional kyphosis was high, but SRS-24 scores were not significantly affected in patients with PJK. The sagittal C7 plumb was not significantly more positive in PJK patients. No patient, radiographic, or instrumentation variables were identified as risk factors for developing PJK.

Pseudarthrosis in primary fusions for adult idiopathic scoliosis: incidence, risk factors, and outcome analysis.

Study Design. A retrospective study. Objective. To analyze the incidence, characteristics, risk factors, and Scoliosis Research Society Instrument-24 (SRS-24) outcome scores of pseudarthrosis in adult idiopathic scoliosis primary fusions. Summary of Background Data. The healing of spinal fusion is complex and difficult to study in a clinical setting. There are no detailed reports on pseudarthrosis in primary fusion for adult idiopathic scoliosis since the introduction of “modern” segmental fixation techniques. Methods. A retrospective chart and radiographic review of 96 patients (average age 42.2 years; range 18.2–62.9 years) with adult idiopathic scoliosis undergoing first time (primary) spinal instrumentation and fusion with a minimum 2-year follow-up (average 5.9 years; range 2–16.8 years) treated at a single institution between 1985 and 2001 were analyzed. Results. Sixteen patients had pseudarthroses (17%). Fifty-nine percent of the pseudarthroses occurred between T9 and L1, and 81% presented with multiple levels involved (2–6 levels). The site of crosslinks or dominoes correlated with pseudarthrosis site in 69%. Pseudarthroses were detected radiologically at 32.4 months (range 12–67 months) postoperatively. Patient age at surgery more than 55 years significantly correlated with pseudarthrosis (P = 0.007). The number of fused levels more than 12 vertebrae is also significantly correlated with pseudarthrosis (P = 0.03). Smoking history and comorbidity did not increase the pseudarthrosis rate (P = 0.71 and 0.19, respectively). A larger preoperative Cobb angle (≥70°) and a greater thoracic kyphosis (T5–T12 >40°) did not correlate with a higher pseudarthrosis rate (P = 0.76 and 0.73, respectively). Thoracolumbar kyphosis (T10–L2 ≥20°) correlated with a significantly higher pseudarthrosis rate (P < 0.0001). Preoperative global sagittal and coronal imbalance did not increase the pseudarthrosis rate (P = 0.45 and 0.62, respectively). Patients with pseudarthrosis had lower SRS-24 scores than those without (P = 0.01). Conclusion. The incidence of pseudarthrosis following adult idiopathic scoliosis primary fusion was 17%. The pseudarthrosis was most likely to occur at the thoracolumbar junction. Older patients (>55 years), longer fusion (>12 vertebrae), and those with thoracolumbar kyphosis (≥20°) demonstrated increased risk for pseudarthrosis. Patients’ outcomes as measured by the SRS-24 were “negatively” affected by the pseudarthrosis.

Thoracolumbar deformity arthrodesis to L5 in adults: the fate of the L5-S1 disc.

Study Design. A retrospective clinical and radiographic analysis of long adult deformity fusions terminating at L5. Objectives. To define the results of thoracolumbar fusions to L5 in adult deformity patients with critical evaluation for potential subsequent L5-S1 disc degeneration and L5 implant loosening. Summary of Background Data. Few studies have reported the results of long adult fusions to L5 and the potential for subsequent advanced L5-S1 disc degeneration is unknown. Materials and Methods. Thirty-four consecutive patients fused from the thoracic spine to L5 at a single institution were evaluated at a mean follow-up of 5.6 years (2.1–14.3 years). SRS-24 functional outcome questionnaire results were obtained for all patients at most recent follow-up. Results. By latest follow-up, subsequent advanced L5-S1 disc degeneration (SAD) developed in 19 of 31 patients (61%) assessed as having “healthy” discs before surgery. SAD was associated with a forward shift in sagittal balance (P = 0.02) and need for revision surgery (P = 0.02). Risk factors for the development of SAD were preoperative positive sagittal balance (P = 0.01), younger age (P = 0.03), and the presence of even mild radiographic degeneration before surgery (P = 0.004). Loss of L5 implant fixation occurred in six patients (18%) and was associated with deep seating of L5 within the pelvis (P = 0.0001). Inferior SRS-24 outcome measures were associated with preoperative advanced L5-S1 disc degeneration and the development of postoperative sagittal imbalance. Conclusions. Subsequent L5-S1 DDD developed in 61% of patients after long adult fusions to L5 and was associated with a significant loss of sagittal alignment and an increased likelihood for or definite need for another operation. Loss of L5 implant fixation is not uncommon, especially in patients with a deep-seated L5 vertebra.

Perioperative halo-gravity traction in the treatment of severe scoliosis and kyphosis.

Study Design. A retrospective analysis of patients that underwent perioperative halo-gravity traction as an adjunct to modern instrumentation methods in the treatment of severe scoliosis and kyphosis. Objective. To review the clinical and radiographic results of perioperative halo-gravity traction in several time periods. Summary of Background Data. Few reports to our knowledge review the use of perioperative and intraoperative halo-gravity traction in this patient population. Methods. A total of 33 patients with severe operative scoliosis, kyphoscoliosis, or kyphosis were studied based on hospital records, standing pretreatment, traction (before anterior/posterior fusion), postoperative (each stage), and final radiographs. Patients were analyzed by age at date of examination (range, 2–20 years; mean, 13.8 years), gender (18 male, 15 female), major coronal curve magnitude (range, 22°–158°; average, 84°), major compensatory coronal curve magnitude (range, 8°–123°; average, 51°), major sagittal curve magnitude (range, 13°–143°; average, 78°), traction protocol, and procedure type. Halo-traction-related, short- and long-term complications were noted in each case. Results. The major coronal curve reduced 38° or 46% after posterior spinal fusion compared to pretreatment radiographs. At an average of 44 months radiographic follow-up (range, 24–107 months), the loss of correction averaged 7° for major coronal curves and 4° of thoracic kyphosis. Clinical complications were noted in the perioperative and long-term time periods. Conclusions. The treatment of severe scoliosis can be very challenging despite the benefits of modern instrumentation methods, especially if there is a significant kyphosis or a history of intraspinal pathology. Halo-gravity traction is a safe, well-tolerated method of applying gradual, sustained traction to maximize postoperative correction in this difficult population. There were no permanent neurologic deficits in this series.

Comparison of surgical treatment in Lenke 5C adolescent idiopathic scoliosis: anterior dual rod versus posterior pedicle fixation surgery: a comparison of two practices.

Study Design. Multicenter analysis of 2 groups of patients surgically treated for Lenke 5C adolescent idiopathic scoliosis (AIS). Objective. Compare patients with Lenke 5C scoliosis surgically treated with anterior spinal fusion with dual rod instrumentation and anterior column support with patients surgically treated with posterior release and pedicle screw instrumentation. Summary of Background Data. Treatment of single, structural, lumbar, and thoracolumbar curves in patients with AIS has been the subject of some debate. Advocates of the anterior approach assert that their technique spares posterior musculature and may save distal fusion levels, and that with dual rods and anterior column support the issues with nonunion and kyphosis have been obviated. Advocates of the posterior approach assert that with the change to posterior pedicle screw based instrumentation that correction and levels are equivalent, and the posterior approach avoids the issues with nonunion and kyphosis. This report directly compares the results of posterior versus anterior instrumented fusions in the operative treatment of adolescent idiopathic Lenke 5C curves. Methods. We analyzed 62 patients with Lenke 5C based on radiographic and clinical data at 2 institutions: 31 patients treated with posterior, pedicle-screw instrumented fusions at 1 institution (group PSF); and 31 patients with anterior, dual-rod instrumented fusions at another institution (group ASF). Multiple clinical and radiographic parameters were evaluated and compared. Results. The mean age, preoperative major curve magnitude, and preoperative lowest instrumented vertebral (LIV) tilt were similar in both groups (age: PSF = 15.5 years, ASF = 15.6 years; curve size: PSF = 50.3° ± 7.0°, ASF = 49.0° ± 6.6°; LIV tilt: PSF = 27.5° ± 6.5°, ASF = 27.8° ± 6.2°). After surgery, the major curve corrected to an average of 6.3° ± 3.2° (87.6% ± 5.8%) in the PSF group, compared with 12.1° ± 7.4° (75.7% ± 14.8%) in the ASF group (P < 0.01). At final follow-up, the major curve measured 8.0° ± 3.0° (84.2% ± 5.8% correction) in the PSF group, compared with 15.9° ± 9.0° (66.6% ± 17.9%) in the ASF group (P = 0.01). This represented a loss of correction of 1.7° ± 1.9° (3.4% ± 3.7%) in the PSF group, and 3.8° ± 4.2° (9.4% ± 10.7%) in the ASF group (P = 0.028). The LIV tilt decreased to 4.1° ± 3.4° after surgery in the PSF group, and 4.5° ± 3.7° in the ASF group. At final follow-up, the LIV tilt was 5.1° ± 3.5° in the PSF group, and 4.5° ± 3.7° in the ASF group. EBL was identical in both groups, and length of hospital stay was significantly (P < 0.01) shorter in the PSF group (4.8 vs. 6.1 days). There were no complications in either group which extended hospital stay or required an unplanned second surgery. Conclusion. At a minimum of 2-year follow-up, adolescents with Lenke 5C curves demonstrated statistically significantly better curve correction, less loss of correction over time, and shorter hospital stays when treated with a posterior release with pedicle screw instrumented fusion compared with an anterior instrumented fusion with dual rods for similar patient populations.

Effect of uncovertebral joint excision on the motion response of the cervical spine after total disc replacement

Study Design. In vitro biomechanical study. Objective. To quantify the effects of uncinatectomy on cervical motion after total disc replacement (TDR). Summary of Background Data. The effect of uncinatectomy on TDR motion is unknown. Partial uncinatectomy may be required to decompress the foramen; however, the residual uncinates can potentially limit TDR motion and serve as a source of progressive spondylosis. Complete resection of the uncinates may decrease this risk yet endanger destabilizing the segment. Methods. Seven human cervical spines (C3–C7) (age, 63.4 ± 6.9 years) were tested first intact and then after implantation of a metal-on-polyethylene ball-and-socket semiconstrained prosthesis at C5–C6. Following this, gradually increased uncinatectomy was performed in the following order: 1) right partial-posteromedial (two thirds), 2) right complete, and 3) bilateral complete resection. Specimens were tested in flexion-extension, lateral bending, and axial rotation (±1.5 Nm). Flexion-extension was tested under 150 N follower preload. Results. TDR without uncinatectomy increased C5–C6 flexion-extension range of motion from 8.4° ± 3.5° to 11.6° ± 3.4°, but statistical significance was not reached (P > 0.05). Lateral bending decreased from 6.2° ± 2.2° to 3.1° ± 1.4°, with a trend for statistical significance (P = 0.07). Axial rotation decreased from 5.5° ± 2.4° to 4.3° ± 1.4° after the implantation (P > 0.05). Both right partial and right complete uncinatectomy resulted in nearly symmetrical restoration of lateral bending to intact values and significantly increased flexion-extension compared with intact (P ≤ 0.05); however, axial rotation still did not differ from intact (P > 0.05). Complete bilateral resection also restored lateral bending to intact values (7.3° ± 2.7°, P > 0.05); however, it resulted in significant increase in range of motion in flexion-extension (14.1° ± 3.0°, P ≤ 0.05) and axial rotation (8.7° ± 2.4°, P ≤ 0.05). Conclusion. Unilateral complete or even partial uncinatectomy can normalize lateral bending after TDR. Bilateral complete uncinatectomy is not necessary to restore lateral bending and may result in significantly increased range of motion in flexion-extension and axial rotation compared with intact values.

Biomechanical evaluation of segmental occipitoatlantoaxial stabilization techniques.

Study Design. Biomechanical study using human cadaveric cervical spines. Objective. To evaluate the construct stability of 3 different segmental occipitoatlantoaxial (C0–C1–C2) stabilization techniques. Summary of Background Data. Different C0–C1–C2 stabilization techniques are used for unstable conditions in the upper cervical spine, all with different degrees of risk to the vertebral artery. Techniques with similar stability but less risk to the vertebral artery may be advantageous. Methods. Six human cadaveric cervical spines (C0–C5) (age: 74 ± 5.0 years) were used. After testing the intact spines, instability was created by transecting the transverse and alar ligaments. The spines were instrumented from the occiput to C2 using 3 different techniques which varied in their attachment to C2. All spines had 6 screws placed into the occiput along with lateral mass screws at C1. The 3 variations used in attachment to C2 were (1) C2 crossing laminar screws, (2) C2 pedicle screws, and (3) C1–C2 transarticular screws. The C1 lateral mass screws were removed before placement of the C1–C2 transarticular screws. Range of motion across C0–C2 was measured for each construct. The data were analyzed using repeated measures ANOVA. The following post hoc comparisons were made: (1) intact spine versus each of the 3 techniques, (2) laminar screw technique versus the pedicle screw technique, and (3) laminar screw technique versus the transarticular screw technique. The level of significance was α = 0.01 (after Bonferroni correction for 5 comparisons). Results. All 3 stabilization techniques significantly decreased range of motion across C0–C2 compared to the intact spine (P < 0.01). There was no statistical difference among the 3 stabilization methods in flexion/extension and axial rotation. In lateral bending, the technique using C2 crossing laminar screws demonstrated a trend toward increased range of motion compared to the other 2 techniques. CT scans in both axial and sagittal views demonstrated greater proximity to the vertebral artery in the pedicle and transarticular screw techniques compared to the crossing laminar screw technique. Conclusion. Occipitoatlantoaxial stabilization techniques using C2 crossing laminar screws, C2 pedicles screws, and C1–C2 transarticular screws offer similar biomechanical stability. Using the C2 crossing laminar screw technique may offer an advantage over the other techniques due to the reduction of the risk to the vertebral artery during C2 screw placement.