In vivo Mouse Model of Spinal Implant Infection.

Spine implant infections portend poor outcomes as diagnosis is challenging and surgical eradication is at odds with mechanical spinal stability. The purpose of this method is to describe a novel mouse model of spinal implant infection (SII) that was created to provide an inexpensive, rapid, and accurate in vivo tool to test potential therapeutics and treatment strategies for spinal implant infections. In this method, we present a model of posterior-approach spinal surgery in which a stainless-steel k-wire is transfixed into the L4 spinous process of 12-week old C57BL/6J wild-type mice and inoculated with 1 x 103 CFU of a bioluminescent strain of Staphylococcus aureus Xen36 bacteria. Mice are then longitudinally imaged for bioluminescence in vivo on post-operative days 0, 1, 3, 5, 7, 10, 14, 18, 21, 25, 28, and 35. Bioluminescence imaging (BLI) signals from a standardized field of view are quantified to measure in vivo bacterial burden. To quantify bacteria adhering to implants and peri-implant tissue, mice are euthanized and the implant and surrounding soft tissue are harvested. Bacteria are detached from the implant by sonication, cultured overnight and then colony forming units (CFUs) are counted. The results acquired from this method include longitudinal bacterial counts as measured by in vivo S. aureus bioluminescence (mean maximum flux) and CFU counts following euthanasia. While prior animal models of instrumented spine infection have involved invasive, ex vivo tissue analysis, the mouse model of SII presented in this paper leverages noninvasive, real time in vivo optical imaging of bioluminescent bacteria to replace static tissue study. Applications of the model are broad and may include utilizing alternative bioluminescent bacterial strains, incorporating other types of genetically engineered mice to contemporaneously study host immune response, and evaluating current or investigating new diagnostic and therapeutic modalities such as antibiotics or implant coatings.

Increasing loads and diminishing returns: a biomechanical study of direct vertebral rotation.

STUDY DESIGN: Biomechanical simulation of DVR and pure-moment testing on thoracic spines. OBJECTIVES: Characterize load-deformation response of thoracic spines under DVR maneuvers until failure, and compare to pure-moment testing of same spines. Despite reports of surgical complications, few studies exist on increase in ROM under DVR torque. Biomechanical models predicting increases from surgical releases have consistently used "pure-moments", a standard established for non-destructive measurement of ROM. Yet, DVR torque is not accurately modeled using pure moments and, moreover, magnitudes of torque applied during DVR maneuvers may be substantially higher than pure-moment testing. METHODS: Cadaveric thoracic spines (N = 11) were imaged, then prepared. Polyaxial pedicle screws were implanted at T7-T10 after surgical releases. Bilateral facetectomies and Ponte osteotomies were completed at T10-T11. A custom apparatus, mounted into an 8-dof MTS load frame, was used to attach to pedicle screws, allowing simulation of surgical DVR maneuvers. Motions of vertebrae were measured using optical motion tracking. Torque was increased until rupture of the T10-T11 disc or fracture at the pedicle screw sites at any level. The torque-rotation behavior was compared to its behavior under pure-moment testing performed prior to the DVR maneuver. RESULTS: Under DVR maneuvers, failure of the T10-T11 discs accompanied in most cases by pedicle screw loosening, occurred at 13.7-54.7 Nm torque, increasing axial rotation by 1.4°-8.9°. In contrast, pure-moment testing (4 Nm) increased axial rotation by only 0.0°-0.9°. CONCLUSIONS: DVR resulted in substantially greater correction potential increases compared to pure-moment testing even at the same torque. These results suggest increased flexibility obtained by osteotomies and facetectomies is underestimated using pure-moment testing, misrepresenting clinical expectations. The present study is an important and necessary step toward the establishment of a more accurate and ultimately surgically applied model. LEVEL OF EVIDENCE: III.

Progress not panacea: vancomycin powder efficacy and dose evaluated in an in vivo mouse model of spine implant infection.

BACKGROUND: Intrawound vancomycin powder (VP) has been rapidly adopted in spine surgery with apparent benefit demonstrated in limited, retrospective studies. Randomized trials, basic science, and dose response studies are scarce. PURPOSE: This study aims to test the efficacy and dose effect of VP over an extended time course within a randomized, controlled in vivo animal experiment. STUDY DESIGN/SETTING: Randomized controlled experiment utilizing a mouse model of spine implant infection with treatment groups receiving vancomycin powder following bacterial inoculation. METHODS: Utilizing a mouse model of spine implant infection with bioluminescent Staphylococcus aureus, 24 mice were randomized into 3 groups: 10 infected mice with VP treatment (+VP), 10 infected mice without VP treatment (No-VP), and 4 sterile controls (SC). Four milligrams of VP (mouse equivalent of 1 g in a human) were administered before wound closure. Bioluminescence imaging was performed over 5 weeks to quantify bacterial burden. Electron microscopy (EM), bacterial colonization assays (Live/Dead) staining, and colony forming units (CFU) analyses were completed. A second dosing experiment was completed with 34 mice randomized into 4 groups: control, 2 mg, 4 mg, and 8 mg groups. RESULTS: The (+VP) treatment group exhibited significantly lower bacterial loads compared to the control (No-VP) group, (p<.001). CFU analysis at the conclusion of the experiment revealed 20% of mice in the +VP group and 67% of mice in the No-VP group had persistent infections, and the (+VP) treatment group had significantly less mean number of CFUs (p<.03). EM and Live/Dead staining revealed florid biofilm formation in the No-VP group. Bioluminescence was suppressed in all VP doses tested compared with sterile controls (p<.001). CFU analysis revealed a 40%, 10%, and 20% persistent infection rate in the 2 mg, 4 mg, and 8 mg dose groups, respectively. CFU counts across dosing groups were not statistically different (p=.56). CONCLUSIONS: Vancomycin powder provided an overall infection prevention benefit but failed to eradicate infection in all mice. Furthermore, the dose when halved also demonstrated an overall protective benefit, albeit at a lower rate. CLINICAL SIGNIFICANCE: Vancomycin powder is efficacious but should not be viewed as a panacea for perioperative infection prevention. Dose alterations can be considered, especially in patients with kidney disease or at high risk for seroma.

Telehealth: a novel approach for the treatment of nondisplaced pediatric elbow fractures.

Telehealth has seldom been used in the field of pediatric orthopaedics. The purpose of this study is to assess the efficacy of telehealth as a tool for the follow-up of children with nondisplaced elbow fractures. We hypothesize that patients treated via telehealth will have comparable clinical outcomes as those treated at our institution, with increased patient satisfaction. We conducted a randomized trial, which included 52 children with type I supracondylar humeral fractures, or occult elbow injuries, divided in two groups, based on the type of care provided during the fourth-week follow-up appointment: cast removal at our institution (group A) or cast removal at home via telehealth appointment (group B). The time duration and professional fees for this week 4 follow-up were calculated. Patients in both groups returned to our institution for a final follow-up in week 8. We measured the amount of fracture displacement, range of motion, pain, and patient satisfaction. There was no statistically significant difference in fracture displacement, range of motion, or pain scores between groups. The mean length of the fourth-week clinical encounter was higher in group A than group B (47.2 vs. 17.6 min, respectively; P < 0.001). Initially, the mean patient satisfaction scores were nearly identical in both groups (97%) until patients in group A were made aware of this difference in time duration, at which their mean satisfaction score decreased to 76.4% (P = 0.05). The use of telehealth as a tool in the treatment of nondisplaced pediatric elbow fractures is appealing. Patients managed via telehealth had higher satisfaction rates and spent only a third of the time for their clinical encounter.

The combined administration of vancomycin IV, standard prophylactic antibiotics, and vancomycin powder in spinal instrumentation surgery: does the routine use affect infection rates and bacterial resistance?

BACKGROUND: Surgical site infections (SSI) poses significant risk following spinal instrumentation surgery. The 2013 North American Spine Society (NASS) Evidence-Based Clinical Guidelines found that the incidence of SSI in spine surgery ranged from 0.7-10%, with higher rates with medical comorbidities. National guidelines currently recommend first-generation cephalosporins as first line prophylaxis. Due to an increase in MRSA cases in our institution, a combined antibiotic strategy using vancomycin IV, standard prophylactic antibiotics, and vancomycin powder was implemented for all spinal instrumentation surgeries. METHODS: All spinal instrumentation surgeries performed at this institution from 2013-2016 were identified. Chart review was then performed to identify the inclusion and exclusion criteria, demographic data, diagnosis, type of surgery performed, and bacterial culture results. Rates of SSI, as defined by the Center for Disease Control (CDC), were calculated and antibiotic resistance was determined. As control, SSIs were identified and reviewed from 2010, prior to the implementation of the combined strategy. RESULTS: One thousand and seventy four subjects were identified in the combined cohort. Mean age was 52.3 years, 540 males (50.2%), 534 females (49.8%). There were 960 primary surgeries (89.4%), 114 cases revision surgeries (10.6%). Cervical myelopathy (27.9%), lumbar stenosis (16.2%), lumbar spondylolisthesis (14.0%), and scoliosis (pediatric and adult)/deformity (13.7%) were leading diagnoses. The standard prophylactic antibiotic was cefazolin IV in 524 cases (48.8%), gentamicin IV in 526 cases (49.0%), vancomycin powder was used in 72.3% of cases. Four SSI cases out of 1,074 were identified (0.37%), 3 deep and 1 superficial, with no antibiotic resistance. In the control group, there were 11 infections of 892 cases (1.23%). There were significantly lower rates of SSI in the combined group versus control (P=0.05). CONCLUSIONS: The combined antibiotic strategy led to low SSI rates in this retrospective case control study. Limitations of this study include retrospective design and small sample size. A large multicenter randomized clinical trial may provide further insight in the effectiveness of this strategy. Level of evidence 3. Clinical relevance: the combined antibiotic protocol may be considered in institutions with concern for SSI and methicillin resistant infections associated with spinal instrumentation surgeries.

Combinatory antibiotic therapy increases rate of bacterial kill but not final outcome in a novel mouse model of Staphylococcus aureus spinal implant infection.

BACKGROUND: Management of spine implant infections (SII) are challenging. Explantation of infected spinal hardware can destabilize the spine, but retention can lead to cord compromise and biofilm formation, complicating management. While vancomycin monotherapy is commonly used, in vitro studies have shown reduced efficacy against biofilm compared to combination therapy with rifampin. Using an established in vivo mouse model of SII, we aim to evaluate whether combination therapy has increased efficacy compared to both vancomycin alone and infected controls. METHODS: An L-shaped, Kirschner-wire was transfixed into the L4 spinous process of 12-week-old C57BL/6 mice, and inoculated with bioluminescent Staphylococcus aureus. Mice were randomized into a vancomycin group, a combination group with vancomycin plus rifampin, or a control group receiving saline. Treatment began on post-operative day (POD) 7 and continued through POD 14. In vivo imaging was performed to monitor bioluminescence for 35 days. Colony-forming units (CFUs) were cultured on POD 35. RESULTS: Bioluminescence peaked around POD 7 for all groups. The combination group had a 10-fold decrease in signal by POD 10. The vancomycin and control groups reached similar levels on POD 17 and 21, respectively. On POD 25 the combination group dropped below baseline, but rebounded to the same level as the other groups, demonstrating a biofilm-associated infection by POD 35. Quantification of CFUs on POD 35 confirmed an ongoing infection in all three groups. CONCLUSIONS: Although both therapies were initially effective, they were not able to eliminate implant biofilm bacteria, resulting in a rebound infection after antibiotic cessation. This model shows, for the first time, why histologic-based, static assessments of antimicrobials can be misleading, and the importance of longitudinal tracking of infection. Future studies can use this model to test combinations of antibiotic therapies to see if they are more effective in eliminating biofilm prior to human trials.

Flexibility of thoracic spines under simultaneous multi-planar loading.

PURPOSE: The corrective potential of two posterior-only destabilization procedures for scoliosis deformity was quantified under single and multi-planar loading using cadaveric spines. METHODS: Ten full-length human cadaveric thoracic spines were mounted in an 8-df servohydraulic load frame. Cyclic, pure moments were applied in: (1) flexion-extension, (2) lateral bending, (3) axial rotation, (4) flexion-extension with axial rotation, and (5) lateral bending with axial rotation at 0.5°/s, to ±4 Nm. Each specimen was tested intact, and again after nine en bloc bilateral total facetectomies, and one, two, three, and four levels of Ponte osteotomies. Motion was measured throughout loading using optical motion tracking. RESULTS: Under single-plane loading, facetectomies and Ponte osteotomies increased thoracic spine flexibility in all three planes. Compared to total facetectomies, higher per-level increases were seen following Ponte osteotomies, with increases in total range of motion (total ROM) of up to 2.7° in flexion-extension, 1.4° in lateral bending, and 3.1° in axial rotation following each osteotomy. Compared to the facetectomies, four supplemental osteotomies increased total ROM by 23 % in flexion (p < 0.01) and 8 % in axial rotation (p < 0.01). Increases in lateral bending were smaller. Under multi-planar loading, each Ponte osteotomy provided simultaneous increases of up to 1.4°, 1.6°, and 2.2° in flexion-extension, lateral bending, and axial rotation. CONCLUSIONS: Ponte osteotomies provided higher per-level increases in ROM under single-plane loading than total facetectomies alone. Further, Ponte osteotomies provided simultaneous increase in all three planes under multi-planar loading. These results indicated that, to predict the correction potential of a surgical release, multi-planar testing may be necessary.

Management of Terminal Osseous Overgrowth of the Humerus With Simple Resection and Osteocartilaginous Grafts.

BACKGROUND: Osseous overgrowth is a common complication in children after humeral transcortical amputation. Capping tibial overgrowth with the proximal fibula has been shown to be the most effective treatment. However, best treatment practices are not clear for the humerus. We compared patients treated surgically for humeral osseous overgrowth with simple resection or autologous osteocartilaginous graft to determine if this treatment were as effective in the humerus as it has been in the tibia. METHODS: A retrospective review of humeral amputees from 1987 to 2011 at a pediatric hospital was performed. Patients with 2 years follow-up who underwent surgical treatment for established humeral overgrowth were included. Patients initially managed with simple resection were compared with those managed with autologous osteocartilaginous grafts. Descriptive statistics were calculated for demographic and outcome variables. T tests and χ tests were used to compare differences between groups. RESULTS: Eighteen humeri in 16 patients met inclusion criteria. Mean age at surgery was 8.3 (2.6 to 13.6) years and mean follow-up was 6.3 (1.5 to 10.4) years. Thirteen humeri underwent simple resection, with recurrent overgrowth in 9, and revision surgery in 8 at a mean 2.6 years. Five humeri were primarily managed with autologous osteocartilaginous grafts. Two developed non-overgrowth-related complications at 1 and 42 months. Including revision procedures after simple resection, 10 humeri were managed with autologous osteocartilaginous grafts. Thirty percent (3/10) required revision surgery; however, there were no cases of recurrent overgrowth. χ comparison showed lower rates of complications (P=0.004) and reoperation (P=0.012) with capping as compared with simple resection. CONCLUSIONS: Autologous osteocartilaginous capping of the humerus has a significantly lower rate of complications and reoperation compared with simple resection. However, the capping procedure has the potential for other complications related to difficulty with graft fixation. Surgeons should be aware that the outcomes are not as consistent as when the technique is applied to osseous overgrowth of the tibia and anticipate the possibilities of hardware prominence and difficulty with fixation. LEVEL OF EVIDENCE: Level 3-therapeutic-retrospective comparative.

Novel in vivo mouse model of implant related spine infection.

Post-operative spine infections are a challenge, as hardware must often be retained to prevent destabilization of the spine, and bacteria form biofilm on implants, rendering them inaccessible to antibiotic therapy, and immune cells. A model of posterior-approach spinal surgery was created in which a stainless steel k-wire was transfixed into the L4 spinous process of 12-week-old C57BL/six mice. Mice were then randomized to receive either one of three concentrations (1 × 102 , 1 × 103 , and 1 × 104 colony forming units (CFU)) of a bioluminescent strain of Staphylococcus aureus or normal saline at surgery. The mice were then longitudinally imaged for bacterial bioluminescence to quantify infection. The 1 × 102 CFU group had a decrease in signal down to control levels by POD 25, while the 1 × 103 and 1 × 104 CFU groups maintained a 10-fold higher signal through POD 35. Bacteria were then harvested from the pin and surrounding tissue for confirmatory CFU counts. All mice in the 1 × 104 CFU group experienced wound breakdown, while no mice in the other groups had this complication. Once an optimal bacterial concentration was determined, mice expressing enhanced green fluorescent protein in their myeloid cells (Lys-EGFP) were utilized to contemporaneously quantify bacterial burden, and immune response. Neutrophil fluorescence peaked for both groups on POD 3, and then declined. The infected group continued to have a response above the control group through POD 35. This study, establishes a noninvasive in vivo mouse model of spine implant infection that can quantify bacterial burden and host inflammation longitudinally in real time without requiring animal sacrifice. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:193-199, 2017.

Strength of Thoracic Spine Under Simulated Direct Vertebral Rotation: A Biomechanical Study.

BACKGROUND: Direct vertebral rotation (DVR) has gained increasing popularity for deformity correction surgery. Despite large moments applied intraoperatively during deformity correction and failure reports including screw plow, aortic abutment, and pedicle fracture, to our knowledge, the strength of thoracic spines has been unknown. Moreover, the rotational response of thoracic spines under such large torques has been unknown. PURPOSE: Simulate DVR surgical conditions to measure torsion to failure on thoracic spines and assess surgical forces. STUDY DESIGN: Biomechanical simulation using cadaver spines. METHODS: Fresh-frozen thoracic spines (n = 11) were evaluated using radiographs, magnetic resonance imaging (MRI) and dual-energy x-ray absorptiometry. An apparatus simulating DVR was attached to pedicle screws at T7-T10 and transmitted torsion to the spine. T11-T12 were potted and rigidly attached to the frame. Strain gages measured the simulated surgical forces to rotate spines. Torsional load was increased incrementally till failure at T10-T11. Torsion to failure at T10-T11 and corresponding forces were obtained. RESULTS: The T10-T11 moment at failure was 33.3 ± 12.1 Nm (range = 13.7-54.7 Nm). The mean applied force to produce failure was 151.7 ± 33.1 N (range = 109.6-202.7 N), at a distance of approximately 22 cm where surgeons would typically apply direct vertebral rotation forces. Mean right rotation at T10-T11 was 11.6°±5.6°. The failure moment was significantly correlated with bone mineral density (Pearson coefficient 0.61, p = .047). Failure moment also positively correlated with radiographic degeneration grade (Spearman rho > 0.662, p < .04) and MRI degeneration grade (Spearman rho = 0.742, p = .01). CONCLUSION: The present study indicated that with the advantage of lever arms provided with DVR techniques, relatively small surgical forces, <200 N, can produce large moments that cause irreversible injury. Although further studies are required to establish the safety of surgical deformity correction surgeries, the present study provides a first step in the quantification of thoracic spine strength.

Challenging the Conventional Standard for Thoracic Spine Range of Motion: A Systematic Review.

BACKGROUND: Segmental motion is a fundamental characteristic of the thoracic spine; however, studies of segmental ranges of motion have not been summarized or analyzed. The purpose of the present study was to present a summary of the literature on intact cadaveric thoracic spine segmental range of motion in each anatomical plane. METHODS: A systematic MEDLINE search was performed with use of the terms "thoracic spine," "motion," and "cadaver." Reports that included data on the range of motion of intact thoracic human cadaveric spines were included. Independent variables included experimental details (e.g., specimen age), type of loading (e.g., pure moments), and applied moment. Dependent variables included the ranges of motion in flexion-extension, lateral bending, and axial rotation. RESULTS: Thirty-three unique articles were identified and included. Twenty-three applied pure moments to thoracic spine specimens, with applied moments ranging from 1.5 to 8 Nm. Estimated segmental range of motion pooled means ranged from 1.9° to 3.8° in flexion-extension, from 2.1° to 4.4° in lateral bending, and from 2.4° to 5.2° in axial rotation. The sums of the range of motion pooled means (T1 to T12) were 28° in flexion-extension, 36° in lateral bending, and 45° in axial rotation. CONCLUSIONS: The pooled ranges of motion were similar to reported in vivo motions but were considerably smaller in magnitude than the frequently referenced values reported prior to the widespread use of biomechanical testing standards. Improved reporting of biomechanical testing methods, as well as specimen health, may be beneficial for improving on these estimations of segmental cadaveric thoracic spine range of motion.

Association between body mass index-for-age and slipped capital femoral epiphysis: the long-term risk for subsequent slip in patients followed until physeal closure.

BACKGROUND: Children who present with idiopathic slipped capital femoral epiphysis (SCFE) have an increased risk of developing bilateral disease. Predicting which patients will develop problems with bilateral hips is important for determining treatment algorithms. This is a retrospective observational study that evaluates the relationship and risk between body mass index (BMI)-for-age and unilateral and bilateral SCFE in patients followed until physeal closure. METHODS: This is a retrospective study of all patients with SCFE presenting to one institution from 1998-2005. Using the Center for Disease Control (CDC) references, BMI-for-age was calculated for each patient. The patients were followed up until complete closure of the bilateral proximal femoral physes, which was considered completion of the study. Statistical analysis for significant differences between groups was performed using the Kruskal-Wallis test for equality of populations. A logistic regression, controlling for age and gender, was used to identify BMI-for-age as a risk factor and to determine the significance of the odds ratios (ORs) for the relevant categorical variables-obese, overweight and healthy weight. RESULTS: Eighty patients (56 male, 24 female) presented to a single institution between 1998 and 2005 with a diagnosis of SCFE. The mean age of patients was 12.2 years at initial presentation (range 8.5-16). Forty-eight patients (32 male, 16 female) presented with unilateral SCFE, with 22 of the 48 patients having a BMI for-age percentile ≥95 %. Thirty-two patients (24 male, 8 female) presented with bilateral SCFE, with 29 of the 32 patients having a BMI-for-age percentile ≥95 %. Patients with a BMI-for-age ≥95 % had a significantly increased risk of presentation with bilateral slips (OR 4.83; relative risk [RR] 3.01; p < 0.05]. All but one patient in this study with bilateral SCFE or unilateral SCFE with subsequent contralateral involvement had a BMI-for-age ≥85 % (44 out of 45 patients). Additionally, the overall risk of developing bilateral SCFE until physeal closure with a BMI-for-age ≥95 % was significantly increased (OR 3.84; RR 2.02; p < 0.05; number needed to treat [NNT] 3.01). CONCLUSIONS: Previous work has established a relationship between BMI and SCFE. The CDC BMI-for-age growth charts more accurately measure obesity in the pediatric population compared to BMI and are therefore a more appropriate reference tool. This study demonstrates an association between obesity measured by BMI-for-age percentiles and SCFE. This study also demonstrates an association between BMI-for-age and risk for bilateral SCFE at presentation as well as overall incidence of developing bilateral SCFE in the obese pediatric population. By defining the at-risk population through BMI-for-age, physicians can screen the pediatric patient population and provide early strategies for therapeutic weight loss which may reduce the incidence of SCFE.

Osteocartilaginous transfer of the proximal part of the fibula for osseous overgrowth in children with congenital or acquired tibial amputation: surgical technique and results.

BACKGROUND: Osseous overgrowth is a common problem in children after tibial transcortical amputation. We present the results of forty-seven children (fifty tibiae) treated for tibial osseous overgrowth with an autologous osteocartilaginous cap from the proximal part of the ipsilateral fibula. METHODS: We reviewed the records of all patients who underwent amputation at a single pediatric hospital from 1990 to 2011. All patients who had been followed for a minimum of two years after undergoing osteocartilaginous capping with the proximal part of the ipsilateral fibula to treat established tibial overgrowth were included. Patients with acquired and congenital amputations were compared. RESULTS: Fifty tibiae in forty-seven patients met our inclusion criteria. There were thirty-one acquired and nineteen congenital amputations. The mean age at surgery was 7.6 years (range, 2.1 to 15.6 years), and the mean duration of follow-up was 7.2 years (range, 2.2 to 15.4 years). Five tibiae (10%) in four patients had recurrence of the overgrowth at a mean of 5.4 years (range, 2.8 to 7.6 years) after the osteocartilaginous transfer. There was no significant difference in the results between children with an acquired amputation and those with a congenital amputation. CONCLUSIONS: At a mean of 7.2 years after autologous osteocartilaginous capping with the proximal part of the fibula, 90% of the limbs had not had recurrent overgrowth. This is a safe and effective treatment of long-bone overgrowth following either congenital or acquired amputation in children.

Outcomes of lower extremity orthopedic surgery in ambulatory children with cerebral palsy with and without gait analysis: results of a randomized controlled trial.

This study examined the impact of gait analysis on surgical outcomes in ambulatory children with cerebral palsy (CP) through a randomized controlled trial. 156 children with CP (94 male; age 10.2 ± 3.7 years) underwent gait analysis and were randomized to two groups: Gait Report group (N = 83), where the referring surgeon received the patient's gait analysis report, and Control group (N = 73), where the surgeon did not receive the gait report. Outcomes were assessed pre- and 1.3 ± 0.5 years post-operatively. An intent-to-treat analysis compared outcomes between the two groups. Outcome measures included the Gillette Functional Activity Questionnaire (FAQ), Gait Deviation Index (GDI), oxygen cost, gross motor function measure, Child Health Questionnaire (CHQ), Pediatric Outcomes Data Collection Instrument (PODCI), and Pediatric Evaluation and Disability Inventory. The outcomes that differed significantly between groups were change in health from the CHQ, which was rated as much better for 56% (46/82) of children in the Gait Report group compared with 38% (28/73) in the Control group (p = 0.04), and upper extremity physical function from the PODCI. Gait outcomes (FAQ and GDI) improved more when over half of the recommendations for a patient were followed or the recommended extent of surgery (none, single, or multi-level) was done (p ≤ 0.04). On average, however, only 42% of the recommendations were followed in the Gait Report group, compared with 35% in the Control group (p = 0.23). This is much less than the >85% reported in previous studies and may account for the lack of differences between groups for some of the outcome measures.

Quantification of Increase in Three-dimensional Spine Flexibility Following Sequential Ponte Osteotomies in a Cadaveric Model.

BACKGROUND: Posterior-only procedures are becoming more popular for treatment of rigid adolescent idiopathic scoliosis, but little is known about the quantitative correction potential for Ponte osteotomies. The objective of this study was to quantify and compare the range of motion of intact multilevel thoracic spine segments with the same segments after each of 3 sequential Ponte osteotomies. METHODS: We tested 5 human cadaveric thoracic spine segments, spanning T-T6, or T7-T12, in an 8-degree-of-freedom servo-hydraulic load frame, monitoring motion of each vertebra with an optical motion tracker. We measured range of motion while we applied cyclic, pure moment loading to produce flexion-extension, lateral bending, and axial rotation at a rate of 0.5°/second, to a maximum of ± 6 Nm. Each specimen was tested intact and after each of 3 sequential Ponte osteotomies. RESULTS: Total range of motion for the segments (either T2-T5 or T8-T11) increased by as much as 1.6° in flexion, 1.5° in extension, 0.5° in lateral bending, and 2.8° in axial rotation with each osteotomy. Because of the variation in initial specimen stiffness, we normalized motions to the intact values. In flexion, average range of motion increased after each osteotomy compared with intact, by 33%, 56%, and 69%. In extension, slightly smaller increases were seen, increasing by as much as 56% after the third osteotomy. In lateral bending, Ponte osteotomies had little effect on range of motion. In axial rotation, range of motion increased by 16%, 29%, and 65% after 3 osteotomies. CONCLUSIONS: Sequential Ponte osteotomies increased range of motion in flexion, extension, and axial rotation, but not in lateral bending. These results suggest that the Ponte osteotomy may be appropriate when using derotational correction maneuvers, or to improve apical lordosis at the apex of curvature during posterior spinal fusion procedures. Although these techniques are effective in gaining correction for kyphotic deformities and rigid curvatures, they add time and blood loss to the procedure.

Influence of gait analysis on decision-making for lower extremity orthopaedic surgery: Baseline data from a randomized controlled trial.

Previous studies examining the influence of gait analysis on surgical decision-making have been limited by the lack of a control group. The aim of this study was to use data from a randomized controlled trial to determine the effects of gait analysis on surgical decision-making in children with cerebral palsy (CP). 178 ambulatory children with CP (110 male; age 10.3±3.8 years) being considered for lower extremity orthopaedic surgery underwent gait analysis and were randomized into one of two groups: gait report group (N=90), where the orthopaedic surgeon received the gait analysis report, and control group (N=88), where the surgeon did not receive the gait report. Data regarding specific surgeries were recorded by the treating surgeon before gait analysis, by the gait laboratory surgeon after gait analysis, and after surgery. Agreement between the treatment done and the gait analysis recommendations was compared between groups using the 2-sided Fisher's Exact test. When a procedure was planned initially and also recommended by gait analysis, it was performed more often in the gait report group (91% vs. 70%, p<0.001). When the gait laboratory recommended against a planned procedure, the plan was changed more frequently in the gait report group (48% vs. 27%, p=0.009). When the gait laboratory recommended adding a procedure, it was added more frequently in the gait report group (12% vs. 7%, p=0.037). These results provide a stronger level of evidence demonstrating that gait analysis changes treatment decision-making and also reinforces decision-making when it agrees with the surgeon's original plan.

Efficacy of intraoperative cell salvage systems in pediatric idiopathic scoliosis patients undergoing posterior spinal fusion with segmental spinal instrumentation.

STUDY DESIGN: Retrospective case-control study. OBJECTIVE: Determine whether intraoperative cell salvage system use during pediatric posterior spinal fusion (PSF) with segmental spinal instrumentation for idiopathic scoliosis decreases intraoperative and perioperative (intraoperative plus postoperative) allogeneic blood transfusion. SUMMARY OF BACKGROUND DATA: Intraoperative cell salvage and reinfusion can reduce or obviate perioperative allogeneic blood transfusion. Despite these benefits, their efficacy in pediatric PSF is unclear. Reported complications include transient hematuria, altered hemostasis, and electrolyte imbalance. METHODS: A total of 54 consecutive idiopathic scoliosis patients were studied: 21 non-cell saver and 33 cell saver patients. Data included age, body mass index, Cobb angle, perioperative hemoglobin levels, mean arterial pressure, surgical time, levels fused, perioperative estimated blood loss, and perioperative transfusions. A chi2 and t tests were performed for intraoperative and perioperative allogeneic transfusion between groups. A regression analysis was performed between selected covariates and allogeneic transfusion. Relative risk analysis examined significant covariates regarding allogeneic transfusion rate. RESULTS: Allogeneic transfusion rates were lower in the cell saver group (6% vs. 55% intraoperative and 18% vs. 55% perioperative, P < 0.05). Mean allogeneic transfusion volumes (mL/kg) were also lower (0.4 vs. 9.1 intraoperative and 1.9 vs. 11.1 perioperative, P < 0.05). Multivariate analysis confirmed these differences were independent of perioperative blood loss, and also demonstrated that surgical time and blood loss were significantly related to allogeneic transfusion volume. The allogeneic transfusion relative risk was 2.04 in patients with surgery >6 hours and 5.87 in patients not receiving cell saver blood. All patients with surgeries >6 hours and estimated blood loss >30% of total blood volume received cell saver system blood. CONCLUSION: Cell saver use decreased allogeneic transfusion, particularly in surgeries >6 hours with estimated blood loss >30% of total blood volume. This study confirms the utility of routine cell saver use during PSF with segmental spinal instrumentation for idiopathic scoliosis.

Decreased body mass index and restrictive lung disease in congenital thoracic scoliosis.

BACKGROUND: Pediatric patients with congenital thoracic scoliosis often have restrictive lung disease and low body weight for age. In other patients with respiratory disorders, the work of breathing can increase basal metabolic demands and predispose patients to cachexia. The primary study aim was to determine if severity of restrictive lung disease, as measured by pulmonary spirometry, correlates to decreased body mass index (BMI) in patients with congenital thoracic scoliosis. A secondary study aim was to determine what patient factors and radiographic measures correlate to low BMI. METHODS: Forty-nine consecutive patients with congenital thoracic scoliosis underwent pulmonary function testing, spinal radiographs, and BMI percentile for age calculations. Severity of restrictive lung disease was quantified by the forced vital capacity percentile (FVC%). The BMI percentile for age was also ranked as normal, moderately, or markedly decreased (0, <1, or <2 SDs below normal, respectively). The t tests were performed between BMI rank and FVC% as well as forced expiratory volume in 1 second (FEV1). A stepwise multivariate linear regression analysis was performed between BMI percentile and FVC%, age, sex, type and extent of previous spine fusion, radiographic measures, and pulmonary spirometry measures. RESULTS: The mean BMI percentile for all patients was 43% (range, 2%-98%). Both FVC% and FEV1 percentile were significantly decreased in patients with abnormal BMI (77% vs 51%, P = 2.78 *10(-1) for FVC%; 75% vs 52%, P = 0.00021 for FEV1 percentile). Multivariate analysis showed that FVC% was the only tested variable that significantly correlated to BMI percentile. There was a 13.6 times higher risk of having an abnormal BMI in patients with moderate to severe restrictive lung disease. CONCLUSIONS: Decreased pulmonary function compromise strongly correlates to low BMI in patients with congenital thoracic scoliosis. When considering moderate to severe restrictive lung disease as defined by FVC%, patients are at much higher risk of being significantly underweight. Body mass index is another important sign of thoracic insufficiency syndrome in these patients. LEVEL OF EVIDENCE: Prognostic case-control study, level III.

Does early thoracic fusion exacerbate preexisting restrictive lung disease in congenital scoliosis patients?

BACKGROUND: Congenital thoracic scoliosis is associated with diminished pulmonary function. Early posterior thoracic spinal fusion surgery may additionally impact pulmonary function beyond the natural history of the disease by further inhibiting thoracic growth. The primary study aim is to determine if early thoracic spine fusion patients have diminished pulmonary function versus untreated patients at a similar age. The secondary study aim is to determine how plain radiographic measurements of thoracic deformity change over time and correlate to pulmonary function in these patients. METHODS: Sequential spinal radiographs and one-time pulmonary function tests were performed in 43 consecutive congenital thoracic scoliosis patients with either a history of early posterior thoracic fusion or no surgery. Multiple stepwise t testing compared the patient-related and radiographic variables in the early surgery and no surgery groups. Multiple stepwise linear regression analysis examined the effect of the variables at final follow-up on forced vital capacity and forced expiratory volume. RESULTS: All patients exhibited decreased forced vital capacity, but there was no difference between early surgery and no surgery groups at an average follow-up age of 10.5 years. A mid- (versus low) thoracic apex, decreased space available for the lung, and decreased age-corrected thoracic width correlated with decreased forced vital capacity. Between initial and final radiographic follow-up, the rate of change in thoracic height and width was decreased in the early surgery versus no surgery group. CONCLUSIONS: Early posterior spinal fusion decreases radiographic measures of thoracic growth over time, but pulmonary function was similar to untreated patients at 10.5 years of age. The data suggest pulmonary function and thoracic size as measured on plain radiographs correlate directly. Therefore, pulmonary function testing at the end of growth should be performed to determine the ultimate pulmonary consequences of early surgery.

Concurrent and discriminant validity of Spanish language instruments for measuring functional health status.

BACKGROUND: Questionnaires translated into languages other than English are often not validated to the same extent as the English versions. This study examined the concurrent and discriminant validity of selected domains related to physical function from Spanish language versions of the Child Health Questionnaire (CHQ), Pediatric Outcomes Data Collection Instrument (PODCI), and Pediatric Evaluation and Disability Inventory (PEDI). METHODS: Concurrent validity was examined in 93 children with cerebral palsy by correlating questionnaire domain scores with Gross Motor Function Measure and Gillette Functional Assessment Questionnaire walking scale scores. Discriminant validity with respect to Gross Motor Function Classification System (GMFCS) level was examined using analysis of variance and nonparametric discriminant analysis. RESULTS: Concurrent validity was demonstrated for 3 domains from the PEDI (Mobility functional skills, tau = 0.62; Mobility caregiver assistance, tau = 0.46-0.55; and Self-care functional skills, tau = 0.30-0.36), 3 domains from the PODCI (Sports and physical function, tau = 0.48-0.51; Transfer and basic mobility, tau = 0.48-0.51; and Upper extremity physical function, tau = 0.28), and 1 domain from the CHQ (Physical function, tau = 0.31-0.36). Discriminant validity was demonstrated for the same domains based on significant decreases in domain scores with increasing GMFCS level. Discriminant validity was highest for the PODCI, which correctly classified 98% (91/93) of subjects into the correct GMFCS level when all 3 domains were considered. CONCLUSIONS: For the first time, concurrent validity and discriminant validity have been demonstrated for the physical function domains of Spanish language versions of the PODCI, PEDI, and CHQ questionnaires. PODCI and PEDI had the highest concurrent validity, and PODCI had the best discriminant ability. CLINICAL RELEVANCE: It is important to examine the validity of instruments when they have been translated from English into other languages. This importance will only increase as the population of non-English-speaking patients expands.