A Clinical Prediction Algorithm to Stratify Pediatric Musculoskeletal Infection by Severity.

OBJECTIVE: There are currently no algorithms for early stratification of pediatric musculoskeletal infection (MSKI) severity that are applicable to all types of tissue involvement. In this study, the authors sought to develop a clinical prediction algorithm that accurately stratifies infection severity based on clinical and laboratory data at presentation to the emergency department. METHODS: An IRB-approved retrospective review was conducted to identify patients aged 0 to 18 who presented to the pediatric emergency department at a tertiary care children's hospital with concern for acute MSKI over a 5-year period (2008 to 2013). Qualifying records were reviewed to obtain clinical and laboratory data and to classify in-hospital outcomes using a 3-tiered severity stratification system. Ordinal regression was used to estimate risk for each outcome. Candidate predictors included age, temperature, respiratory rate, heart rate, C-reactive protein (CRP), and peripheral white blood cell count. We fit fully specified (all predictors) and reduced models (retaining predictors with a P-value ≤0.2). Discriminatory power of the models was assessed using the concordance (c)-index. RESULTS: Of the 273 identified children, 191 (70%) met inclusion criteria. Median age was 5.8 years. Outcomes included 47 (25%) children with inflammation only, 41 (21%) with local infection, and 103 (54%) with disseminated infection. Both the full and reduced models accurately demonstrated excellent performance (full model c-index 0.83; 95% confidence interval, 0.79-0.88; reduced model 0.83; 95% confidence interval, 0.78-0.87). Model fit was also similar, indicating preference for the reduced model. Variables in this model included CRP, pulse, temperature, and an interaction term for pulse and temperature. The odds of a more severe outcome increased by 30% for every 10 U increase in CRP. CONCLUSIONS: Clinical and laboratory data obtained in the emergency department may be used to accurately differentiate pediatric MSKI severity. The predictive algorithm in this study stratifies pediatric MSKI severity at presentation irrespective of tissue involvement and anatomic diagnosis. Prospective studies are needed to validate model performance and clinical utility. LEVEL OF EVIDENCE: Level II-prognostic study.

Effects of Antibiotic Timing on Culture Results and Clinical Outcomes in Pediatric Musculoskeletal Infection.

INTRODUCTION: Musculoskeletal infection (MSI) is a common cause of morbidity and hospital resource utilization in the pediatric population. Many physicians prefer to withhold antibiotics until tissue cultures can be taken in an effort to improve culture yields. However, there is little evidence that this practice improves culture results or outcomes in pediatric MSI. Therefore, investigating the effects of antibiotic timing may lead to improved clinical practice guidelines for treating children with MSI. METHODS: An IRB-approved retrospective review was conducted that identified 113 patients aged 0 to 18 who presented to the pediatric emergency room at a tertiary care children's hospital with MSI from 2008 to 2013. Demographic data, culture results, severity markers, and intervention timing were obtained from the medical record. Logistic regression and Cox survival analysis were performed to determine the relationship of antibiotic timing with culture sensitivity and time to discharge. RESULTS: No difference was seen in culture sensitivity antibiotic administration in either the local (55% culture before antibiotics vs. 89% after antibiotics) or disseminated group (76% before vs. 79% after), which persisted when further accounting for disease severity with C-reactive protein. However, later administration of antibiotics in the local infection group correlated with a decreased likelihood of discharge (3.91 d when cultured before antibiotics vs. 2.93 d when cultured after antibiotics; hazard ratio, 0.53; P<0.05). In patients with disseminated infection, antibiotic administration was not shown to correlate with any difference in time to discharge (hazard ratio, 1.08). CONCLUSIONS: The authors were surprised to find that tissue culture sensitivities were not decreased by antibiotic administration in either local or disseminated MSI, suggesting that antibiotic administration should not be delayed to obtain tissue cultures. The correlation of earlier antibiotic administration with shorter length of stay in children with local MSI led the authors to conclude that antibiotics should be initiated as quickly as possible. Further study is necessary to confirm these findings and establish clinical practice guidelines. LEVEL OF EVIDENCE: Level III-retrospective cohort.

Validation and Modification of a Severity of Illness Score for Children With Acute Hematogenous Osteomyelitis.

BACKGROUND: Children with osteomyelitis demonstrate a wide spectrum of illness. Objective measurement of severity is important to guide resource allocation and treatment decisions, particularly for children with advanced illness. The purpose of this study is to validate and improve a previously published severity of illness scoring system for children with acute hematogenous osteomyelitis (AHO). METHODS: Children with AHO were prospectively studied during evaluation and treatment by a multidisciplinary team who provided care according to evidence-based guidelines to reduce variation. A severity of illness score was calculated for each child and correlated with surrogate measures of severity. Univariate analysis was used to assess the significance of each parameter within the scoring model along with new parameters, which were evaluated to improve the model. The scoring system was then modified by the addition of band count to replace respiratory rate. The modified score was calculated and applied to the prospective cohort followed by correlation with the surrogate measures of severity. RESULTS: One hundred forty-eight children with AHO were consecutively studied. The original severity of illness score correlated well with length of stay and other established measures of severity. Band percent of the white blood cell differential ≥1.5% was found to be significantly associated with severity and chosen to replace respiratory rate in the model. The modified calculated severity scores correlated well with the chosen surrogate measures and significantly differentiated children with osteomyelitis on the basis of causative organism, length of stay, intensive care, surgeries, bacteremia, and disseminated or multifocal disease. CONCLUSIONS: The findings of this study validate the previously published severity of illness scoring tool in large cohort of children who were prospectively evaluated. The replacement of respiratory rate with band count improved the scoring system.

Dilutional coagulopathy in pediatric scoliosis surgery: A single center report.

BACKGROUND: Children undergoing posterior spinal fusion experience high blood loss often necessitating transfusion. An appropriately activated coagulation system provides hemostasis during surgery, but pathologic dysregulation can cause progressive bleeding and increased transfusions. Despite receiving antifibrinolytics for clot stabilization, many patients still require transfusions. AIMS: We sought to examine the association of dilutional coagulopathy with blood loss and blood transfusion in posterior spinal fusion for pediatric scoliosis patients. METHODS: A retrospective, single institution study of children undergoing posterior spinal fusion >6 levels with a standardized, prospective anesthetic protocol utilizing antifibrinolytics. Blood loss was evaluated using a hematocrit-based calculation. To evaluate transfusions, a normalized Blood Product Transfusion calculation was developed. Factors associated with blood loss and blood transfusions were determined by univariate analysis and multivariate regression modeling with multicollinearity and mediation analysis. RESULTS: Patients received 73.7 mL/kg (standard deviation ±30.8) of fluid poor in coagulation factors. Estimated blood loss was 42.6 mL/kg (standard deviation ±18.0). There was a significant association between estimated blood loss and total fluids delivered (Spearman's rho = 0.51, 95% confidence interval 0.33-0.65, P < 0.001). Factors significantly associated with normalized Blood Product Transfusion in this cohort included age, weight, scoliosis type, levels fused, total osteotomies, pelvic fixation, total fluid, maximum prothrombin time, and minimum fibrinogen. Regression modeling showed the best combination of variables for modeling normalized Blood Product Transfusion included patient weight, number of levels fused, total fluid administered, and maximum prothrombin time. CONCLUSION: Blood product transfusion remains a frustrating problem in pediatric scoliosis. Identifying and controlling dilutional coagulopathy in these patients may reduce blood loss and the need for blood transfusion.

A Novel Classification System Based on Dissemination of Musculoskeletal Infection is Predictive of Hospital Outcomes.

BACKGROUND: Musculoskeletal infections (MSKIs) are a common cause of pediatric hospitalization. Children affected by MSKI have highly variable hospital courses, which seem to depend on infection severity. Early stratification of infection severity would therefore help to maximize resource utilization and improve patient care. Currently, MSKIs are classified according to primary diagnoses such as osteomyelitis, pyomyositis, etc. These diagnoses, however, do not often occur in isolation and may differ widely in severity. On the basis of this, the authors propose a severity classification system that differentiates patients based on total infection burden and degree of dissemination. METHODS: The authors developed a classification system with operational definitions for MSKI severity based on the degree of dissemination. The operational definitions were applied retrospectively to a cohort of 202 pediatric patients with MSKI from a tertiary care children's hospital over a 5-year period (2008 to 2013). Hospital outcomes data [length of stay (LOS), number of surgeries, positive blood cultures, duration of antibiotics, intensive care unit LOS, number of days with fever, and number of imaging studies] were collected from the electronic medical record and compared between groups. RESULTS: Patients with greater infection dissemination were more likely to have worse hospital outcomes for LOS, number of surgeries performed, number of positive blood cultures, duration of antibiotics, intensive care unit LOS, number of days with fever, and number of imaging studies performed. Peak C-reactive protein, erythrocyte sedimentation rate, white blood cell count, and temperature were also higher in patients with more disseminated infection. CONCLUSIONS: The severity classification system for pediatric MSKI defined in this study correlates with hospital outcomes and markers of inflammatory response. The advantage of this classification system is that it is applicable to different types of MSKI and represents a potentially complementary system to the previous practice of differentiating MSKI based on primary diagnosis. Early identification of disease severity in children with MSKI has the potential to enhance hospital outcomes through more efficient resource utilization and improved patient care. LEVEL OF EVIDENCE: Level II-prognostic study.

Similar Clinical Severity and Outcomes for Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus Pediatric Musculoskeletal Infections.

BACKGROUND: Prior studies of pediatric musculoskeletal infection have suggested that methicillin-resistant Staphylococcus aureus (MRSA) infections result in worse outcomes compared with infections with methicillin-susceptible S aureus (MSSA) strains. Based on these results, clinical prediction algorithms have been developed to differentiate between MRSA and MSSA early in a patient's clinical course. This study compares hospital outcomes for pediatric patients with MRSA and MSSA musculoskeletal infection presenting to the emergency department at a large tertiary care children's hospital. METHODS: A retrospective study identified pediatric patients with S aureus musculoskeletal infection over a 5-year period (2008-2013) by sequential review of all pediatric orthopedic consults. Relevant demographic information, laboratory values, and clinical outcomes were obtained from the electronic medical record. RESULTS: Of the 91 identified cases of S aureus pediatric musculoskeletal infection, there were 49 cases of MRSA infection (53%) and 42 cases of MSSA infection (47%). There were no significant differences between MRSA and MSSA infections in median hospital length of stay (4.8 vs 5.7 days, P = .50), febrile days (0.0 vs 1.5 days, P = .10), and antibiotic duration (28 vs 34 days, P = .18). Methicillin-resistant S aureus infections were more likely to require operative intervention than MSSA infection (85% vs 62%, P = .15). A logistic regression model based on C-reactive protein, temperature, white blood cell count, pulse, and respiratory rate at presentation demonstrated poor ability to differentiate between MRSA and MSSA infection. CONCLUSIONS: The results demonstrated no significant differences between MSSA and MRSA musculoskeletal infections for most hospital outcomes measured. However, MRSA infections required more operative interventions than MSSA infections. In addition, a predictive model based on severity markers obtained at presentation was unable to effectively differentiate between MRSA and MSSA infection. The clinical utility and capacity for early differentiation of MRSA and MSSA depends on virulence patterns that may vary temporally and geographically.

Pediatric Musculoskeletal Infection: Hijacking the Acute-Phase Response.

Tissue injury activates the acute-phase response mediated by the liver, which promotes coagulation, immunity, and tissue regeneration. To survive and disseminate, musculoskeletal pathogens express virulence factors that modulate and hijack this response. As the acute-phase reactants required by these pathogens are most abundant in damaged tissue, these infections are predisposed to occur in tissues following traumatic or surgical injury. Staphylococcus aureus expresses the virulence factors coagulase and von Willebrand binding protein to stimulate coagulation and to form a fibrin abscess that protects it from host immune-cell phagocytosis. After the staphylococcal abscess community reaches quorum, which is the colony density that enables cell-to-cell communication and coordinated gene expression, subsequent expression of staphylokinase stimulates activation of fibrinolysis, which ruptures the abscess wall and results in bacterial dissemination. Unlike Staphylococcus aureus, Streptococcus pyogenes expresses streptokinase and other virulence factors to activate fibrinolysis and to rapidly disseminate throughout the body, causing diseases such as necrotizing fasciitis. Understanding the virulence strategies of musculoskeletal pathogens will help to guide clinical diagnosis and decision-making through monitoring of acute-phase markers such as C-reactive protein, erythrocyte sedimentation rate, and fibrinogen.

Hemiepiphysiodesis Implants for Late-onset Tibia Vara: A Comparison of Cost, Surgical Success, and Implant Failure.

BACKGROUND: The purpose of this study was to compare hemiepiphysiodesis implants for late-onset tibia vara and to evaluate patient characteristics that may predict surgical failure. METHODS: This is a retrospective review of late-onset tibia vara patients treated with temporary hemiepiphysiodesis from 1998 to 2012. Mechanical axis deviation (MAD), mechanical axis angle, mechanical lateral distal femoral angle, and medial proximal tibial angle were measured on standing bone length radiographs. Surgical failure was defined as residual deformity requiring osteotomy, revision surgery, or MAD exceeding 40 mm at the time of final follow-up. Implant failure was recorded. Costs included implants and disposables required for construct placement. Staple constructs included 2 or 3 staples. Plate constructs included the plate, screws, guide wires, and drill bits. RESULTS: A total of 25 patients with 38 temporary lateral proximal tibia hemiepiphysiodeses met the inclusion criteria. The average body mass index (BMI) was 39.1 kg/m with an average follow-up of 3.0 years (minimum 1 y). Surgical failure occurred in 57.9% of patients. Greater BMI (P=0.05) and more severe deformity (MAD, mechanical axis angle, and medial proximal tibial angle; P<0.01) predicted higher rates of surgical failure. Younger age predicted higher rates of implant failure (P<0.01). There were no differences in surgical or implant failure between staple and plate systems. Hospital costs of plate constructs ($781 to $1244) were 1.5 to 3.5 times greater than the staple constructs ($332 to $498). CONCLUSIONS: Greater BMI, more severe deformity, and younger age were predictive of surgical or implant failure. There was no difference in success between implant types, whereas the cost of plate constructs was 1.5 to 3.5 times greater than staples. The rate of surgical failure was high (58%) and consideration should be given to reserving hemiepiphysiodesis for patients with lower BMI and less severe deformity. In our population, if hemiepiphysiodesis was not offered to patients with BMI>35 or MAD>80 mm varus, the surgical failure rate would diminish to 28%. The failure rate outside these parameters would be 88%. LEVEL OF EVIDENCE: Level II­Prognostic.

Epidemiology, diagnosis, and treatment of pericapsular pyomyositis of the hip in children.

BACKGROUND: The yield of synovial fluid cultures in patients meeting clinical criteria for septic hip arthritis remains low. In the presence of positive blood cultures, these patients are diagnosed and treated as "presumed septic arthritis." We hypothesized that some of these patients may instead have an extra-articular infection, such as pericapsular pyomyositis. METHODS: An IRB-approved prospective study of children with suspected septic hip arthritis at a tertiary care children's hospital over a 2-year time period was conducted. Children were evaluated with a previously published clinical algorithm with the addition of magnetic resonance imaging (MRI). RESULTS: Of the 53 patients presenting with an acutely irritable hip, 32% were found to have pericapsular pyomyositis, whereas 15% were diagnosed with septic arthritis. Although C-reactive protein (CRP, ≥33.1 mg/L) performed well at predicting infection, there were no significant differences in CRP, erythrocyte sedimentation rate, white blood cell count, temperature, or weight-bearing status in children with septic arthritis compared with pericapsular pyomyositis. In addition to MRI, there was a difference in the size of hip effusion on ultrasound, which was significantly smaller in cases of pericapsular pyomyositis. CRP (≥74.3 mg/L) was found to be predictive of need for surgical intervention in children with pericapsular pyomyositis. CONCLUSIONS: Correct anatomic diagnosis of the site of infection is essential for the efficient care of the child. Herein, we found that pericapsular pyomyositis is twice as common as septic arthritis in children presenting with an acutely irritable hip. Clinical algorithms are incapable of differentiating these pathologies suggesting that both be considered under the current diagnosis previously referred to as "presumed septic arthritis." Incorrect diagnosis of a septic arthritis in the presence of a pericapsular pyomyositis could potentially lead to unnecessary debridement of the joint in the presence of extra-articular infection, thus contaminating the joint. Conversely, debriding the joint instead of the epicenter of the infection can prolong the infectious process. For these reasons, we conclude that MRI has the potential to improve the clinical care of children by providing a more precise diagnosis. LEVEL OF EVIDENCE: Level II-"Diagnostic" [Development of diagnostic criteria on the basis of consecutive patients (with universally applied reference "gold" standard)].

Medial approach for drainage of the obturator musculature in children.

BACKGROUND: In a recent study designed to determine the anatomic location of infection in children presenting with acute hip pain, fever, and elevated inflammatory markers, we demonstrated the incidence of infection of the musculature surrounding the hip to be greater than twice that of septic arthritis. Importantly, the obturator musculature was infected in >60% of cases. Situated deep in the pelvis, surrounding the obturator foramen, debridement of these muscles and placement of a drain traditionally requires an extensive ilioinguinal or Pfannenstiel approach, placing significant risk to the surrounding neurovascular structures. We hypothesized that the obturator internus and externus could be successfully debrided using a limited medial approach. METHODS: An IRB-approved prospective study of children (0 to 18 y) evaluated in the pediatric emergency department by an orthopaedic surgeon to rule out septic hip arthritis at a tertiary care children's hospital (July 1, 2010 to June 30, 2012) was conducted. Infected obturator musculature was identified and confirmed using magnetic resonance imaging. Cadaveric dissection was performed comparing the ilioinguinal, Pfannenstiel, and proposed minimally invasive medial approach. The proposed approach was utilized to debride and place drains in 7 consecutive patients. RESULTS: Anatomic information gained from magnetic resonance images of patients with abscess within the obturator musculature, and from the results of cadaveric studies, allowed for planning of a novel surgical approach. We found that through the surgical approach used to perform an osteotomy of the ischium (Tonnis) the obturator externus could be debrided through the adductor brevis and the obturator internus could be debrided through the obturator foramen. Using our medial approach, resolution of symptoms in all children who underwent surgical drainage resulted without complication. CONCLUSIONS: Our medial approach can safely access the obturator musculature for abscess decompression and drain placement with successful results. Advantages to this approach include: lower risk to neurovascular structures within the pelvis, less soft tissue trauma, and similarity to current techniques used for adductor lengthening, medial reduction of the dislocated hip, and osteotomy of the ischium. LEVEL OF EVIDENCE: Level II.

Fingertip injuries: an update on management.

Injuries to the fingertip are common. The goal of treatment is restoration of a painless, functional digit with protective sensation. The amount of soft-tissue loss, the integrity of the nail bed, and the age and physical demands of the patient should be considered when selecting a treatment method. Some new products are effective for management of injuries to the fingertip. The use of 2-octylcyanoacrylate for nail bed repair is faster than suture repair, with equivalent results reported. Dermal regeneration template is effective for coverage of digital injuries with exposed tendons or bones that lack peritenon or periosteum. Although fingertip replantation offers better functional results than does revision amputation, replantation is more technically demanding and requires longer recovery time. Complications associated with management of injuries to the fingertip include nail deformities, insensate digits, and painful neuromas.

Radiographic outcomes of volar locked plating for distal radius fractures.

PURPOSE: To assess the ability of volar locked plating to achieve and maintain normal radiographic parameters for articular stepoff, volar tilt, radial inclination, ulnar variance, and radial height in distal radius fractures. METHODS: We performed a retrospective review of 185 distal radius fractures that underwent volar locked plating with a single plate design over a 5-year period. We reviewed radiographs and recorded measurements for volar tilt, radial inclination, ulnar variance, radial height, and articular stepoff. We used logistic regression to determine the association between return to radiographic standard norms and fracture type. RESULTS: At the first and final postoperative follow-up visits, we observed articular congruence less than 2 mm in 92% of fractures at both times. Normal volar tilt (11°) was restored in 46% at the first follow-up and 48% at the final one. Radial inclination (22°) was achieved in 44% at the first follow-up and 43% at the final one, and ulnar variance (01 ± 2 mm) was achieved in 53% at the first follow-up and 53% at the final one. In addition, radial height (14 ± 1mm) was restored in 14% at the first follow-up and 12% at the final one. More complex, intra-articular fractures (AO class B and C and Frykman types 3, 4, 7, and 8) were less likely to be restored to normal radiographic parameters. However, because of the small sample size for some fracture types, it was difficult to discover significant associations between fracture type and radiographic outcome. CONCLUSIONS: Volar locked plating for distal radius fractures achieved articular stepoff less than 2 mm in most fractures but only restored and maintained normal radiographic measurements for volar tilt, radial inclination, and ulnar variance in 50% of fractures. The ability of volar locked plating to restore and maintain ulnar variance and volar tilt decreased with more complex intra-articular fracture types. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

The spectrum of group A streptococcal joint pathology in the acute care setting.

OBJECTIVES: Group A streptococcus (GAS) is a frequent cause of pediatric musculoskeletal infections including septic arthritis, acute rheumatic fever (ARF), and a more benign arthritis called post-streptococcal reactive arthritis. Children with painful joints are frequently evaluated in the acute care setting, and because the presentation of each of these entities is similar, the diagnosis can be difficult to make. Five cases of children with GAS arthridities are presented to demonstrate the spectrum of GAS-associated joint pathologies encountered in the acute care setting and also to discuss how GAS laboratory tests may assist in the evaluation and management of children presenting with a painful joint. METHODS: Five cases of GAS-associated joint pathology are presented. Evaluation of these patients was conducted using a diagnostic algorithm derived from a literature review of post-streptococcal reactive arthritis and ARF, as well as the current clinical practice guideline for the diagnosis and treatment of septic arthritis. RESULTS: The 5 cases presented include 1 case of transient synovitis, 2 cases of inflammatory synovitis, 1 case of septic arthritis, and 1 case of ARF. CONCLUSIONS: Determining the cause of joint pain in the acute care setting is challenging. The addition of the GAS laboratory tests to a diagnostic algorithm based on clinical examination and monitoring systemic inflammation can help to identify patients with ARF and septic arthritis in the acute care setting. In addition, GAS-specific laboratory tests may help to identify cases of nonseptic, non-ARF GAS joint pathology.