Skeletal muscle and plasma concentrations of cefazolin during complex paediatric spinal surgery.

BACKGROUND: Surgical site infections (SSIs) can have devastating consequences for children who undergo spinal instrumentation. Prospective evaluations of prophylactic cefazolin in this population are limited. The purpose of this study was to describe the pharmacokinetics and skeletal muscle disposition of prophylactic cefazolin in a paediatric population undergoing complex spinal surgery. METHODS: This prospective pharmacokinetic study included 17 children with adolescent idiopathic scoliosis undergoing posterior spinal fusion, with a median age of 13.8 [interquartile range (IQR) 13.4-15.4] yr and a median weight of 60.6 (IQR 50.8-66.0) kg. A dosing strategy consistent with published guidelines was used. Serial plasma and skeletal muscle microdialysis samples were obtained during the operative procedure and unbound cefazolin concentrations measured. Non-compartmental pharmacokinetic analyses were performed. The amount of time that the concentration of unbound cefazolin exceeded the minimal inhibitory concentration for bacterial growth for selected SSI pathogens was calculated. RESULTS: Skeletal muscle concentrations peaked at a median of 37.6 (IQR 26.8-40.0) µg ml(-1) within 30-60 min after the first cefazolin 30 mg kg(-1) dose. For patients who received a second 30 mg kg(-1) dose, the peak concentrations reached a median of 40.5 (IQR 30.8-45.7) µg ml(-1) within 30-60 min. The target cefazolin concentrations for SSI prophylaxis for meticillin-sensitive Staphylococcus aureus (MSSA) and Gram-negative pathogens were exceeded in skeletal muscle 98.9 and 58.3% of the intraoperative time, respectively. CONCLUSIONS: For children with adolescent idiopathic scoliosis undergoing posterior spinal fusion, the cefazolin dosing strategy used in this study resulted in skeletal muscle concentrations that were likely not to be effective for intraoperative SSI prophylaxis against Gram-negative pathogens.

The orthopedists' perspective: bone tumors, scoliosis, and trauma.

Although a detailed, comprehensive look at pediatric orthopedists' use of imaging is beyond the scope of this article, we offer an orthopedist's perspective of the role imaging plays in the care of children with tumors, scoliosis, and trauma. Given the growing, dynamic state of a child's skeleton, the long-term consequences of injury must always be considered.

Complications in children managed with immobilization in a halo vest.

Thirty-seven patients who were three to sixteen years old were managed with immobilization in a halo vest between 1987 and 1993. Twenty-four patients (65 per cent) had the halo vest applied in conjunction with operative arthrodesis of the cervical spine; the remaining thirteen patients (35 per cent) had the halo vest applied to immobilize the cervical spine after trauma. Complications occurred in twenty-five patients (68 per cent). Pin-site infections were the most common complications, developing in twenty-two patients. Grade-II infections (purulent drainage) developed more frequently in children who were eleven years old or more: they were identified in five of fourteen such patients, compared with two of twenty-three patients who were ten years old or less. There was a tendency toward more grade-I infections (non-purulent drainage, with or without erythema) and loosening of the pins in the children who were ten years old or less: eleven of twenty-three such patients had each of those complications, compared with four of fourteen children who were eleven years old or more. Both loosening and infection occurred more frequently at the anterior pin sites. Other complications included one dural penetration, one transient injury of the supraorbital nerve, and three pin-site scars that were considered by the family to be objectionable. There were no complications related to the vest part of the halo vest. Younger patients who had a halo construct with more than four pins (multiple-pin constructs) had a similar rate of complications compared with patients who were managed with a standard four-pin halo construct.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraoperative anaphylaxis due to exposure to latex (natural rubber) in children.

Intraoperative anaphylaxis secondary to exposure to latex is a serious and potentially life-threatening phenomenon that has been recognized more frequently in recent years. Between 1989 and 1992, twenty-one patients had a Type-I (anaphylactic) reaction to latex intraoperatively at The Children's Hospital of Philadelphia. Twelve (57 per cent) of these patients had spina bifida. Six patients (29 per cent) had cerebral palsy, and five of them had a ventriculoperitoneal shunt. Of the remaining three patients, one (5 per cent) had exstrophy of the bladder, one had VATER syndrome, and one had Duchenne muscular dystrophy. All of the patients had had at least two previous operative procedures. Overall, sixteen patients (76 per cent) had a ventriculoperitoneal shunt. The manifestations of the allergic reaction included a rash in fifteen patients (71 per cent), hypotension in fifteen, tachycardia in eleven (52 per cent), bronchospasm in ten (48 per cent), bradycardia in two (10 per ent), and cardiac arrest in two. The symptoms occurred within minutes after the induction of the anesthesia in all but one patient, in whom hypotension and cardiovascular arrest developed approximately one hour after the beginning of the operation. Two patients had a full cardiopulmonary arrest while under the anesthesia. All twenty-one patients responded to management; there were no deaths. Of the six patients who had cerebral palsy, five had been managed with a ventriculoperitoneal shunt because of hydrocephalus following a previous intraventricular hemorrhage that was related to prematurity.(ABSTRACT TRUNCATED AT 250 WORDS)

Occipitocervical arthrodesis in children. A new technique and analysis of results.

A new wiring technique for occipitocervical arthrodesis was used in sixteen consecutive children between 1985 and 1992. The twelve boys and four girls had an average age of nine years and six months (range, two years and five months to nineteen years and three months) at the operation. The arthrodesis was performed between the occiput and the second cervical vertebra in ten patients and between the occiput and the third cervical vertebra in six. The instability was related to congenital anomalies (six patients), decompression for cervical stenosis (four patients), Down syndrome (three patients), trauma (one patient), resection of a tumor (one patient), and neurofibromatosis (one patient). Six patients needed a laminectomy for decompression because of cervical stenosis or for removal of a tumor. All of the patients were managed with an autogenous bone graft from the iliac crest and postoperative immobilization with a halo device. Fusion was achieved in fifteen of the sixteen patients. Complications developed in seven patients. The use of wire fixation, combined with the inherent stability of the bone-graft construct, allowed for removal of the halo device relatively early (range, six to twelve weeks), before the fusion was fully mature. No graft was displaced. All of the patients were followed at least until there was radiographic evidence of fusion (fifteen patients) or until a reoperation was performed (one patient). The average duration of follow-up was thirty-seven months (range, twelve to 108 months).

Results of brace treatment of scoliosis in Marfan syndrome.

STUDY DESIGN: Retrospective review of a defined Marfan population with traditional indications for bracing. OBJECTIVES: To determine the success rate of brace treatment in keeping curves from progressing by more than 5 degrees or exceeding 45 degrees. SUMMARY OF BACKGROUND DATA: Few studies exist regarding brace treatment of Marfan syndrome, and they include many patients with curves of more than 45 degrees, as well as some who are near maturity. All of the prior studies risk the possibility of some selection bias. METHODS: Patients were selected from support groups and several institutions. Inclusion criteria were: Definite diagnosis of Marfan syndrome, curve of 45 degrees or less, Risser sign 2, 1, or 0 at inception of bracing, recommended wear of 18 hours or more per day, and follow-up until maturity or surgery (minimum, 2 years). Success was defined as curve progression of 5 degrees or less and final curve remaining 45 degrees or less. Failure was a final curve of more than 45 degrees. Twenty-four patients met the criteria. There were 15 girls and 9 boys. Twenty-two patients wore a brace as recommended. Two additional patients were unable to tolerate it. RESULTS: Mean age at inception of bracing was 8.7 years (range, 4-12 years). There were 14 double major, 6 thoracic, and 4 thoracolumbar curves with a mean size of 29 degrees at the beginning of bracing. The stated wearing time averaged 21 hours per day. Five patients had significant pain over bony prominences. Although correction of the curve in brace was good (45%), only 4 of the patients had success, and in 20 of the 24 treatment was considered a failure. Mean progression was 6 degrees +/- 8 degrees per year, for a final mean curve of 49 degrees. Sixteen of the patients had, or were advised to have, surgical correction. The difference in age and degree of curvature were not statistically significant between the success and nonsuccess groups. CONCLUSIONS: The success rate for brace treatment of Marfan scoliosis is 17%, which is lower than that reported for idiopathic scoliosis. Possible reasons include increased progressive forces, altered transmission of corrective pressure to the spine, and younger age at inception of bracing. Because there was no control group, it is unknown whether bracing slowed curve progression. Physicians should understand that most patients with Marfan syndrome who have a curve of more than 25 degrees and a Risser sign of 2 or less will reach the surgical range, even with brace treatment.

A technique of occipitocervical arthrodesis in children using autologous rib grafts.

STUDY DESIGN: Description of an operative technique with an illustrative case report. OBJECTIVES: The technique is presented to provide an alternative to iliac crest graft procedures for achieving occipitocervical fusion in children. This technique is particularly useful in children with instability after extensive decompression or laminectomy and in children with a large protuberant occiput. SUMMARY OF BACKGROUND DATA: The majority of techniques previously described for occipitocervical fusion in children rely on corticocancellous iliac crest autograft. Results generally have been promising; however, it can be difficult to harvest enough graft to span large defects after extensive decompression or to contour an iliac crest graft to a protuberant occiput. Structural rib autograft is superior in terms of availability and its unique and modifiable contour. Theoretical benefits of rib graft include superior strength and lower donor site morbidity. METHODS: The surgical technique is described. A case of a 2-year-old boy with Down's syndrome and myelopathy secondary to cervical instability is reviewed. RESULTS: The patient underwent occipitocervical arthrodesis using the technique described. The child made a full neurologic recovery, and at the 2-years follow-up evaluation, the graft had incorporated and the spine was stable. CONCLUSION: A technique of occipitocervical arthrodesis in children is described using autologous rib graft. This procedure was designed to span large defects or to deal with a large protuberant occiput; however, it is also useful for less demanding cases and may offer several advantages compared with procedures relying on iliac crest graft.

A comparison of various angles of halo pin insertion in an immature skull model.

STUDY DESIGN: A basic science biomechanical study involving an animal model. OBJECTIVES: To evaluate the effect of varying angles of halo pin insertion on the force generated at the pin-bone interface, and thereby the stability of the halo pin-bone interaction during insertion. BACKGROUND DATA: Because of variations in the shape and size of the pediatric skull, halo pins often are inserted at various angles rather than perpendicular to the skull. Concern exists that the high complication rate associated with pediatric halo use may result in part from less than ideal structural properties at the halo pin-bone interface. METHODS: The authors used a fetal calf skull model to simulate the thickness and structural properties of the pediatric skull. Halo pins were inserted at angles of 0 degree (perpendicular), 10 degrees, 15 degrees, and 30 degrees into skull segments via a halo ring. Load generated at the pin-bone interface was measured using a modified mechanical testing device. Twenty trials were conducted per angle, with the endpoint being specimen failure, pin penetration, or maximum load. RESULTS: Mean maximum loads per unit thickness were 82.15 +/- 7.54 N/mm at 0 degree, 68.80 +/- 4.79 N/mm at 10 degrees, 51.49 +/- 5.08 N/mm at 15 degrees, and 42.38 +/- 3.51 N/mm at 30 degrees, There was a significant difference between perpendicular insertion (0 degree) and 15 degrees angles of insertion. There was also a significant difference between the 10 degrees and 30 degrees angles of insertion. CONCLUSIONS: Perpendicular halo pin insertion in an immature skull model was shown to result in increased load at the pin-bone interface. This improved structural behavior may help to reduce the incidence of complications of halo application in children.

Anterior vertebral screw strain with and without solid interspace support.

STUDY DESIGN: This in vitro biomechanical study examines segmental anterior vertebral screw strain and solid rod construct stiffness with and without the addition of multilevel, threaded cortical bone dowels in a bovine model. OBJECTIVE: To determine whether strain at the bone-screw interface is higher at the end levels during physiologic range loading, and whether solid interspace support decreases segmental strain on the implant. SUMMARY OF BACKGROUND DATA: Anterior instrumentation provides greater correction and preserves distal motion segments. However, nonunion and implant failure are observed more frequently than with posterior segmental instrumentation, and when observed, loss of fixation occurs at the end levels. METHODS: Eight calf spines underwent mechanical testing in the following sequence: 1) intact condition, 2) anterior release with anterior solid rod and bicortical rib grafts, and 3) anterior release with anterior solid rod and threaded cortical bone dowels (L2-L5). Instrumented vertebral screws were used to assess strain within the vertebral body by the near cortex, whereas an anterior extensometer spanning the instrumented segments was used to measure segmental displacements to calculate construct stiffness. The protocol included axial compression (-400 N), right lateral bending (4 Nm (Newton-meter), away from the implant), and left lateral bending (4 Nm, toward the implant). Statistical analysis included a one-way analysis of variance and a Student-Newman-Keuls post hoc test. A pilot study was performed using four additional specimens loaded for 4000 cycles to investigate macroscopic loosening after fatigue loading. RESULTS: In lateral bending toward the implant, the strain was higher at both end levels, with no differences between the rib and dowel reconstructions. The stiffness values were greater than the intact values for both groups. In lateral bending away from the implant, the strain also was higher at both end screws, and the dowel group had less strain at these levels than the rib group. Both groups were stiffer than the intact condition, and the dowel group was stiffer than the rib group. Axial compressive strain also was higher at the end levels, but this difference did not reach statistical significance. The rib group did not reach intact stiffness values, whereas the dowel group was stiffer than the intact condition. The fatigue study showed gross loosening at one or both end levels in all cases. CONCLUSIONS: Higher strain was observed at the bone-screw interface in both end screws of an anterior solid rod construct during lateral bending, which correlates with the clinically observed failure location. This suggests that physiologic range loading may predispose to failure at the end levels. Disc space augmentation with solid implants increased construct stiffness in all three load paths and decreased strain at the end levels in lateral bending away from the implant. Future implant modifications should achieve better fixation at the end screws, and the current model provides a means to compare different strategies to decrease strain at these levels.

Augmentation of an anterior solid rod construct with threaded cortical bone dowels. A biomechanical study.

STUDY DESIGN: This static, nondestructive, in vitro biomechanical study examines anterior solid rod construct stiffness following the addition of multilevel, threaded cortical bone dowels in a bovine model. A comparison is made with a clinically relevant posterior construct with and without an anterior release. OBJECTIVES: To determine if the addition of solid, multilevel disc space implants will increase construct rigidity, while maintaining or enhancing anterior column length. SUMMARY OF BACKGROUND DATA: Anterior instrumentation for thoracolumbar and lumbar scoliosis has achieved greater correction and preserved distal motion segments; however, kyphosis over the instrumented segments and nonunion have been observed more frequently than with posterior segmental spinal instrumentation. METHOD: Fifteen calf spines underwent mechanical testing. Group A (n = 7) included anterior constructs: 1) intact, 2) anterior release/rod/rib graft (L2-L5), and 3) anterior release/rod/dowels (L2-L5). Group B (n = 8) included posterior constructs: 1) intact, 2) posterior rod without anterior release (T13-L5), 3) posterior rod (T13-L5)/anterior release/rib graft (L2-L5). The protocol included axial compression (-600 N), axial rotation (+7 Nm), flexion/extension (+7.5 Nm), and lateral bending (+7.5 Nm). An anterior extensometer measured segmental displacements to calculate construct stiffness. Lateral radiographs evaluated alignment for the anterior constructs. Statistical analysis involved a one way analysis of variance (ANOVA) and a Student-Newman-Keuls post hoc test. RESULTS: All reconstructions restored stiffness to intact values with the exception of the dowels alone in axial rotation. The rod/dowel construct was stiffer than all other groups in axial compression, flexion/extension, and lateral bending, with the exception of the posterior rod without discectomy, which was superior in flexion and statistically similar in extension, lateral bending, and axial rotation. The anterior construct with rib graft was equivalent to the posterior construct with rib graft in all modes of testing. The dowels created greater lordosis than the bicortical rib grafts. CONCLUSIONS: Disc space augmentation increased stiffness except in axial rotation, in which values were restored to the intact level. Stiffness was superior to a clinically relevant posterior instrumentation comparison group following anterior release, and was equivalent to a posterior construct without anterior release except in anterior flexion. In addition, the implants enhanced lordosis. Increased rigidity should improve rates of arthrodesis, while maintenance of sagittal alignment may prevent pathologic compensatory curves in adjacent spinal segments. Further research is required to determine the optimal method of achieving structural interspace support.

Orthopedic management of children with cerebral palsy.

Children with cerebral palsy are a diverse group. Many variables affect their orthopedic care, including age, type and severity of involvement, functional abilities, previous treatment, and access to treatment. The overall goals of orthopedic management include the detection of specific orthopedic problems at an early stage when simple and more effective treatment options may be instituted. Orthopedic intervention currently is almost more of an art than a science. With continued efforts and research, it is hoped that new and better ways will be found to improve the care of these children.

Benign pediatric bone tumors. Evaluation and treatment.

Several recent significant advances have been made in the evaluation and treatment for bone lesions in children. Most advances have come as a result of better imaging of these lesions, namely with magnetic resonance imaging. When a child presents with a bone lesion, several aids allow the treating physician to develop a differential diagnosis. Both recent advance and newer techniques in the diagnosis and treatment of children with benign bone lesions are discussed.

Malignant bone tumors of childhood.

Improvements in diagnosis and treatment have increased survival for many children with malignant bone tumors. New molecular genetic discoveries are providing insights into the mechanisms of tumorigenesis and may provide novel therapeutic modalities based on interfering with aberrant transcriptional activation by hybrid transcripts.

Differential diagnosis of pediatric musculoskeletal masses.

MR imaging plays a major role in the evaluation of children with soft tissue and bone tumors. While the imaging characteristics of these lesions are often nonspecific, MR imaging provides valuable information on the extent of disease and relationship of tumors to the neurovascular bundle and other vital structures. This article reviews the radiographic and MR imaging appearances and clinical presentations of a wide range of musculoskeletal masses that occur in children.

Cervical spine disorders in infants and children.

The evaluation of children with cervical spine disorders requires an understanding of the anatomic and developmental features that are particular to the pediatric spine. In this article, cervical spine developmental anatomy is briefly reviewed, along with common radiographic features of the pediatric cervical spine. The epidemiology, clinical presentation, and management of congenital cervical anomalies are considered. The evaluation and management of pediatric cervical trauma are also reviewed. Other disorders with common cervical spine involvement, such as skeletal dysplasias, connective tissue disorders, inflammatory arthritides, and storage disorders, are discussed.

Orthopaedics in the developing world: present and future concerns.

Half of the world's population lack access to adequate primary health care, and two thirds lack access to orthopaedic care. Globally, the need for health care outstrips the available resources. This problem is compounded in the developing world by a lack of trained medical personnel, a lack of medical facilities, and, in many regions, an inability to access existing facilities. There is little specific epidemiologic data about the exact burden of musculoskeletal disease in these countries, but most agree that it is reasonable to assume that it will increase. In the least developed and developing nations, problems with access are related to fundamental issues such as infrastructure, physical facilities, equipment, and trained personnel. There are a number of ways in which the orthopaedic community can become involved in ameliorating the burden. Education is the most effective method of providing a sustainable solution. The objective of educational organizations should be to train local health-care workers at all levels in their own environment to provide sustainable and appropriate care so that the programs become self-sufficient and ensure a continued supply of competent medical personnel.

The problem of Monteggia fracture-dislocations in children.

When a Monteggia fracture is recognized and treated immediately, the results are excellent. Poor results are mostly caused by initially missing the diagnosis. Operative intervention is usually required for those fractures that are unstable after manipulation or recognized too late after injury.

Fractures of the olecranon and radial neck in children.

Over one half of radial neck fractures are associated with other injuries about the elbow. Most radial neck fractures can be treated with closed reduction or with percutaneous probing, even if the other associated injuries require open reduction. The results are good, although radiologic imperfections may be seen after healing. In the older child, olecranon fractures that have significant displacement usually require open reduction with internal fixation.

Train injuries in children.

OBJECTIVE: To describe the pattern of injuries sustained in pediatric victims of train accidents. DESIGN: Retrospective review of patients identified in a search of two trauma registries for the years 1984-1994. SETTING: Two pediatric level one trauma centers in one metropolitan area. PATIENTS: Between 1984 and 1994, seventeen children were identified as treated for injuries sustained in train accidents. Children pronounced dead at the scene and those injured when a car was struck by a train were excluded. INTERVENTION: ATLS protocols were followed. All open musculoskeletal injuries were treated with multiple operative irrigation and debridement procedures and broad spectrum antibiotics. MAIN OUTCOME MEASUREMENTS: Variables included the following: age, sex, mechanism of injury, circumstances surrounding the injuries, all injuries sustained, operations performed during the acute hospitalization, subsequent operations, level of amputation(s), complications, and cost and length of hospitalization. RESULTS: Presenting injuries included eight patients with ten complete amputations and eight patients with ten near-complete amputations. The average number of operative procedures for the survivors during the initial hospitalization was 5.7 (range three to sixteen). Five patients (five extremities) required amputation revision to a more proximal level after the initial surgical intervention but prior to definitive wound closure. Secondary surgical procedures have been required in 50% of survivors to date. The financial cost of these injuries is substantial, with acute hospitalization costs averaging $61,000. CONCLUSION: Pediatric survivors of train-pedestrian accidents are likely to suffer isolated musculoskeletal injuries, the majority of which are amputations of the lower extremity. These injuries require multiple operative debridements and frequent revision to higher levels of amputation are expected. The percentage of these injuries in children at play around railroad tracks emphasizes the need for limitation of access to railroad areas and for prevention through public education.

Major pediatric hand trauma associated with fireworks.

OBJECTIVES: To characterize the injury pattern and economic impact of major pediatric hand trauma secondary to fireworks. DESIGN: Retrospective. SETTING: Pediatric Level I trauma center. INTERVENTION: N/A MAIN OUTCOME MEASUREMENTS: Fractures, amputations, soft tissue defects, length of hospitalization, number and type of procedures performed were obtained from charts, radiographs, and operative reports. Hospital charges were obtained from the billing office. PATIENTS/PARTICIPANTS: Records of patients with a diagnosis of fireworks-related injuries admitted over a period of ten years were reviewed. Twenty-two patients were identified to have sustained twenty-two hand injuries. The group consisted of nineteen boys and three girls, with an average age of 9.3 years (range, 4 to 17 years). RESULTS: There were thirty-one fractures, nineteen amputations, and one dislocation. The nineteen amputations occurred in nine hands. Local skin graft or flap coverage was required in six hands acutely, and delayed soft tissue procedures were performed on four hands. Four hands had digital neurovascular injuries; two required microsurgical repairs at the time of injury, and two were irreparable. Resource use included: average hospital stay of 4.3 days (range, 0 to 20), average number of trips to the operating room, 1.2 (range, 0 to 3), and average hospital charges of $11,582 (range, $1,035 to $39,489). CONCLUSIONS: This study illustrates the severity of pediatric hand injuries associated with fireworks and the significant burden placed on medical resources in treating these injuries. Efforts toward public education and legislative reforms may help to prevent these unnecessary injuries.