Antonio Faundez

Evidence showing the relationship between sagittal balance and clinical outcomes in surgical treatment of degenerative spinal diseases: a literature review

The measure of radiographic pelvic and spinal parameters for sagittal balance analysis has gained importance in reconstructive surgery of the spine and particularly in degenerative spinal diseases (DSD). Fusion in the lumbar spine may result in loss of lumbar lordosis (LL), with possible compensatory mechanisms: decreased sacral slope (SS), increased pelvic tilt (PT) and decreased thoracic kyphosis (TK). An increase in PT after surgery is correlated with postoperative back pain. A decreased SS and/or abnormal sagittal vertical axis (SVA) after fusion have a higher risk of adjacent segment degeneration. High pelvic incidence (PI) increases the risk of sagittal imbalance after spine fusion and is a predictive factor for degenerative spondylolisthesis. Restoration of a normal PT after surgery is correlated with good clinical outcome. Therefore, there is a need for comparative prospective studies that include pre- and postoperative spinopelvic parameters and compare complication rate, degree of disability, pain and quality of life.

Clinical and radiological outcome of anterior-posterior fusion versus transforaminal lumbar interbody fusion for symptomatic disc degeneration: a retrospective comparative study of 133 patients

Abundant data are available for direct anterior/posterior spine fusion (APF) and some for transforaminal lumbar interbody fusion (TLIF), but only few studies from one institution compares the two techniques. One-hundred and thirty-three patients were retrospectively analyzed, 68 having APF and 65 having TLIF. All patients had symptomatic disc degeneration of the lumbar spine. Only those with one or two-level surgeries were included. Clinical chart and radiologic reviews were done, fusion solidity assessed, and functional outcomes determined by pre- and postoperative SF-36 and postoperative Oswestry Disability Index (ODI), and a satisfaction questionnaire. The minimum follow-up was 24 months. The mean operating room time and hospital length of stay were less in the TLIF group. The blood loss was slightly less in the TLIF group (409 vs. 480 cc.). Intra-operative complications were higher in the APF group, mostly due to vein lacerations in the anterior retroperitoneal approach. Postoperative complications were higher in the TLIF group due to graft material extruding against the nerve root or wound drainage. The pseudarthrosis rate was statistically equal (APF 17.6% and TLIF 23.1%) and was higher than most published reports. Significant improvements were noted in both groups for the SF-36 questionnaires. The mean ODI scores at follow-up were 33.5 for the APF and 39.5 for the TLIF group. The patient satisfaction rate was equal for the two groups.

Biomechanical comparison of anterior lumbar interbody fusion and transforaminal lumbar interbody fusion.

Study Design An in vitro biomechanical comparison of 2 fusion techniques, anterior lumbar interbody fusion (ALIF) and transforaminal lumbar interbody fusion (TLIF), on cadaveric human spines. Objective To compare the immediate construct stability, in terms of range of motion (ROM) and neutral zone, of ALIF, including 2 separate approaches, and TLIF procedures with posterior titanium rod fixation. Summary of Background Data Both ALIF and TLIF have been used to treat chronic low back pain and instability. In many cases, the choice between these 2 techniques is based only on personal preference. No biomechanical performance comparison between these 2 fusion techniques is available to assist surgical decision. Methods Twelve cadaveric lumbar motion segments were loaded sinusoidally at 0.05 Hz and 5 Nm in unconstrained axial rotation, lateral bending and flexion extension. Specimens were randomly divided into 2 groups with 6 in each group. One group was assigned for TLIF whereas the other group for ALIF. In the ALIF group, there were 3 steps. First, the lateral ALIF procedure with the anterior longitudinal ligament (ALL) intact was performed. Afterwards, the ALL was cut without removing the ALIF cage. Finally, another appropriately sized ALIF cage was inserted anteriorly. Biomechanical tests were conducted after each step. Results In the ALIF group, the lateral ALIF and subsequent anterior ALIF reduced segmental motion significantly (P=0.03) under all loading conditions. Removing the ALL increased ROM by 59% and 142% in axial rotation and flexion extension, respectively (P=0.03). The anterior ALIF approach was able to achieve similar biomechanical stability of the lateral approach in lateral bending and flexion extension (P>0.05) under all loading conditions. The TLIF procedure significantly reduced the range of motion compared with the intact state (P=0.03). However, no statistical difference was detected between the TLIF group and the ALIF group (P>0.05). Conclusions Both ALIF and TLIF procedures combined with posterior instrumentation significantly improved construct stability of intact spinal motion segments. However, there was no statistical difference between these 2 fusion techniques. The 2 ALIF approaches (lateral and anterior) also had similar construct stability even though anterior longitudinal ligament severing significantly reduced stability.

Position of interbody spacer in transforaminal lumbar interbody fusion: effect on 3-dimensional stability and sagittal lumbar contour

Study Design Biomechanical study. Objective To test 2 different intervertebral positions of a semilunar cage and their effects on 3-dimensional stability and segmental lordosis in a model of transforaminal lumbar interbody fusion (TLIF). Summary of Background Data In his original TLIF description, Harms recommended decortication of endplates, followed by placement of mesh cages in the middle-posterior intervertebral third. Subsequent studies presented conflicting recommendations: anterior placement of the spacer-cage for better load-sharing versus placement on the stronger posterolateral endplate regions. Methods Six human lumbar spinal functional units were first tested intact. TLIF was performed using a semilunar poly-ether-ether-ketone cage randomly inserted in the anterior (TLIF-A) or posterior (TLIF-P) disc space. Pedicle screws and rods were added. Unconstrained pure moments in axial-torsion, lateral-bending (LB), and flexion-extension (FE) were applied under 0.05 Hz and ±5 Nm sinusoidal waveform. Segmental motions were recorded. Range of motion (ROM) and neutral zone (NZ) were calculated. Pairwise comparisons were made using nonparametric Wilcoxon-matched pairs signed rank sum test with statistical significance set at P<0.05. Results TLIF-A and TLIF-P significantly decreased ROM (P<0.05) of the intact spinal functional unit, in FE and LB. In axial-torsion, decrease of ROM after TLIF procedures was not significant (P>0.05). Δ-ROM between TLIF-A and TLIF-P was not significant (P>0.05). TLIF-A and TLIF-P significantly decreased NZ in LB (P<0.05). In FE, TLIF-P significantly decreased NZ (P<0.05); TLIF-A showed a trend toward significance (P=0.09). Δ-NZ between TLIF-A and TLIF-P was not significant (P>0.05). Segmental lordosis of TLIF-A and TLIF-P on C-arm views showed angle differences within the range of measurement error of Cobb angles. Conclusions Difference in ROM and NZ between anterior (TLIF-A) or posterior (TLIF-P) positions was not statistically significant. Similarly, both positions did not influence segmental lordosis.

Vertebral reconstruction with cortical allograft: long-term evaluation.

Abstract. Reconstruction of large anterior vertebral column defects is indicated in a number of pathological conditions including tumor, infection, trauma and post-traumatic deformity. Several substitutes and techniques are available for the functional restoration of the vertebral column. Vascularized bone transfers, autografts, allografts or xenografts have been used, as well as metal or ceramic implants. All of these bear potential advantages and drawbacks in terms of associated morbidity of graft harvesting, disease transmission, mechanical failure, implant incorporation and overall long-term clinical outcome. In the present paper we report our experience with the use of freeze-dried, gamma-irradiated, cortical allograft for the reconstruction of large, anterior segmental defects of the spine, involving at least one vertebral body with its two adjacent discs. Cortical allografts were used in 67 cases operated for a variety of conditions. No case of disease transmission, infection or long-term mechanical graft failure occurred in our entire series, with a mean follow-up of 31 months. Fusion and mechanical stability was reliably obtained. Specific advantages include the absence of donor site morbidity, the possibilities for exact trimming to the size of the defect, superior mechanical strength as compared to available autograft, and reliable fusion with the host bone with partial bone remodeling, preventing fatigue failure. We conclude that freeze-dried, irradiated cortical allografts are safe and effective for anterior reconstruction of the spine.

Bone morphogenetic protein use in spine surgery—complications and outcomes: a systematic review

PurposeBecause of significant complications related to the use of autologous bone grafts in spinal fusion surgery, bone substitutes and growth factors such as bone morphogenetic protein (BMP) have been developed. One of them, recombinant human (rh) BMP-2, has been approved by the Food and Drug Administration (FDA) for use under precise conditions. However, rhBMP-2-related side effects have been reported, used in FDA-approved procedures, but also in off-label use.A systematic review of clinical data was conducted to analyse the rhBMP-2-related adverse events (AEs), in order to assess their prevalence and the associated surgery practices.MethodsMedline search with keywords “bone morphogenetic protein 2”, “lumbar spine”, “anterolateral interbody fusion” (ALIF) and the filter “clinical trial”. FDA published reports were also included. Study assessment was made by authors (experienced spine surgeons), based on quality of study designs and level of evidence.ResultsExtensive review of randomised controlled trials (RCTs) and controlled series published up to the present point, reveal no evidence of a significant increase of AEs related to rhBMP-2 use during ALIF surgeries, provided that it is used following FDA guidelines. Two additional RCTs performed with rhBMP-2 in combination with allogenic bone dowels reported increased bone remodelling in BMP-treated patients. This AE was transient and had no consequence on the clinical outcome of the patients. No other BMP-related AEs were reported in these studies.ConclusionsThis literature review confirms that the use of rhBMP-2 following FDA-approved recommendations (i.e. one-level ALIF surgery with an LT-cage) is safe. The rate of complications is low and the AEs had been identified by the FDA during the pre-marketing clinical trials. The clinical efficiency of rhBMP-2 is equal or superior to that of allogenic or autologous bone graft in respect to fusion rate, low back pain disability, patient satisfaction and rate of re-operations. For all other off-label use, the safety and effectiveness of rhBMP-2 have not been established, and further RCTs with high level of evidence are required.

Pedicle subtraction osteotomy in the thoracic spine and thoracolumbar junction: a retrospective series of 28 cases

PurposePedicle subtraction osteotomy is a well-described surgical technique for treatment of kyphotic deformity in the spine. It is not widely used for treatment of thoracic kyphosis. We present the first documented series of 28 patients who underwent this procedure in 3 international centers. These patients presented with severe deformity with a wide range of aetiologies.IndicationsKyphosis larger than 70 degrees, which is demonstrably rigid based on dynamic imaging.Materials and methods28 patients underwent surgery following pre-op neurological and radiographic assessment to fully assess the deformity. A triangular osteotomy was carried out using intraoperative navigation techniques. The patients were assessed post-operatively again with clinical and radiographic parameters at regular follow-up.ResultsThe mean ODI score after surgery was 24.7 (16–42) while the pre-op was 53.4 (38–76). Mean thoracic kyphosis was improved from 64.2° (±20.1°) to 41.1° (±17.4°) resulting in a mean sagittal correction of 23.1°. Mean segmental correction at the PSO for all 28 cases was 17.8° (±8.1°). Stratified by region we found different values for the PSO correction: between T1 and T5 (6 cases) it was 17.5° (±5.4°) and between T6 and T9 (4 cases) 18.2° (±4.7°) and between T10 and L1 (18 cases) 26.2° (±5.2°). FBI index was 22.3° pre-op and improved to 7.8° post-op. Calculations were performed with Microsoft excel (2011 Microsoft, Redmond, WA).ConclusionsGlobal sagittal balance was statistically improved in this series as demonstrated by FBI and C7 SVA correction.

AN UNUSUAL MONTEGGIA TYPE-I EQUIVALENT FRACTURE IN A CHILD

A six-year-old girl sustained a Monteggia type-I equivalent fracture of the right forearm. We describe the method of treatment of this rare fracture and its outcome.

Revision of transforaminal lumbar interbody fusion using anterior lumbar interbody fusion: a biomechanical study in nonosteoporotic bone

OBJECT Transforaminal lumbar interbody fusion (TLIF) is a popular fusion technique for treating chronic low-back pain. In cases of interbody nonfusion, revision techniques for TLIF include anterior lumbar interbody fusion (ALIF) approaches. Biomechanical data of the revision techniques are not available. The purpose of this study was to compare the immediate construct stability, in terms of range of motion (ROM) and neutral zone (NZ), of a revision ALIF procedure for an unsuccessful TLIF. An in vitro biomechanical comparison of TLIF and its ALIF revision procedure was conducted on cadaveric nonosteoporotic human spine segments. METHODS Twelve cadaveric lumbar motion segments with normal bone mineral density were loaded in unconstrained axial torsion, lateral bending, and flexion-extension under 0.05 Hz and +/- 6-nm sinusoidal waveform. The specimens underwent TLIF (with posterior pedicle fixation) and anterior ALIF (with intact posterior fixation). Multidirectional flexibility testing was conducted following each step. The ROM and NZ data were measured and calculated for each test. RESULTS Globally, the TLIF and revision ALIF procedures significantly reduced ROM and NZ compared with that of the intact condition. The revision ALIF procedures achieved similar ROM as the TLIF procedure. CONCLUSIONS Revision ALIF maintained biomechanical stability of TLIF in nonosteoporotic spines. Revision ALIF can be performed without sacrificing spinal stability in cases of intact posterior instrumentation.

Variables associated with remission in spinal surgical site infections

BACKGROUND There is few medical literature regarding factors associated with remission after surgical and medical treatment of postoperative spine infections. METHODS Single-centre case-control study 2007-2014. Cluster-controlled Cox regression model with emphasis on surgical and antibiotic-related parameters. RESULTS Overall, we found 66 episodes in 48 patients (49 episodes with metalwork) who had a median follow-up of 2.6 years (range, 0.5 to 6.8 years). The patients had a median of two surgical debridements. The median duration of antibiotic therapy was 8 weeks, of which 2 weeks parenteral. Clinical recurrence after treatment was noted in 13 episodes (20%), after a median interval of 2 months. In 53 cases (80%), the episodes were considered as in remission. By multivariate analyses, no variable was associated with remission. Especially, the following factors were not significantly related to remission: number of surgical interventions [hazard ratio (HR) 0.9; 95% confidence interval (CI), 0.8-1.1]; infection due to Staphylococcus aureus (HR 0.9; 0.8-1.1), local antibiotic therapy (HR 1.2; 0.6-2.4), and, duration of total (HR 1.0; 0.99-1.01) (or just parenteral) (HR 1.0; 0.99-1.01) antibiotic use. CONCLUSIONS In patients with post-operative spine infections, remission is achieved in 80%. The number of surgical debridement or duration of antibiotic therapy shows no association with recurrence, suggesting that individual risk factors might be more important than the duration of antibiotic administration.