The effect of coronal plane angulation on patient reported outcome measures of operatively treated distal femur fractures: A multi-center prospective evaluation.

OBJECTIVES: The goal of this trial was to determine whether coronal plane angulation affects functional and clinical outcomes after the fixation of distal femur fractures. DESIGN: Multicenter, randomized controlled trial SETTING: 20 academic trauma centers PATIENTS/PARTICIPANTS: 156 patients with distal femur fractures were enrolled. 123 patients were followed 12 months. There was clinical outcome data available for 105 patients at 3 months, 95 patients at 6 months and 81 patients at one year. INTERVENTION: Lateral locked plating or retrograde intramedullary nailing MAIN OUTCOME MEASUREMENTS: Radiographic alignment, functional scoring including SMFA, Bother Index, and EQ-5D. Clinical scoring of walking ability, need for ambulatory support and ability to manage stairs. RESULTS: At 3 months, there was no difference between groups (varus, neutral or valgus) with respect to any of the clinical functional outcome scores measured. At 6 months, compared to those with neutral alignment, patients with varus angulation had a worse Stair Climbing score (4.33 vs. 2.91, p = 0.05). At 12 months, the average patient with neutral or valgus alignment needed less ambulatory support than the average patient in varus. Walking distance ability was no different between the groups at any time point. With respect to the validated patient-based outcome scores, we found no statistical difference in in the SMFA, Bother, or EQ-5D between patients with valgus or varus mal-alignment and those with neutral alignment at any time point (p > 0.05). Regardless of coronal angulation, the SMFA trended towards lower (improved) scores over time, while EQ-5D scores for patients with varus angulation did not improve over time. CONCLUSIONS: Valgus angulation and neutral angulation may be better tolerated in terms of clinical outcomes like stair climbing and need for ambulatory support than varus angulation, though patient reported outcome measures like the SMFA, Bother Index and EQ-5D show no statistical significance. Most patients with distal femur fractures tend to improve during the first year after injury but many remain significantly affected at 12 months post injury.

Inadvertent intraforaminal iliosacral screw placement despite apparent appropriate positioning on intraoperative fluoroscopy.

We present the case of an intraforaminal iliosacral screw placed percutaneously with aid of C-arm using inlet, outlet, and lateral views of the pelvis. The iliosacral screw was placed above the S1 foramen on the outlet view, into the middle of S1 via the ala on the inlet view, and below the cortical shadow of the ala on the lateral view. The patient was neurologically intact postoperatively, but began to complain of severe radicular pain in the S1 distribution down to the foot within 1 week postsurgery. There was mild weakness of plantar flexion. Postoperative computed tomography scan showed that the iliosacral screw was within the S1 foramen. Because of the tangential nature of the S1 foramen, slight posterior placement of the screw into the S1 body and not into the promontory resulted in violation of the foramen despite it being above the cortical shadow on the outlet view.

Histomorphic analysis of the development of the pars interarticularis and its association with isthmic spondylolysis.

STUDY DESIGN: Descriptive study analyzing the histologic development of human fetal lumbar spine pars interarticularis. OBJECTIVES: To delineate the histologic development of the fetal pars interarticularis and correlate the development of the pars with isthmic spondylolysis. SUMMARY OF BACKGROUND DATA: Isthmic spondylolysis is present in 5% to 6% of the population. The incidence at birth is zero but rises sharply to 5% at age 4 to 5 years. The origin of the lesion is unknown; however, the current theory states that isthmic spondylolysis results from a fatigue fracture through a congenitally weak pars interarticularis. No study exists investigating the histologic development of the pars. METHODS: Microscopic examination of lumbar spines of human fetuses aged 8-20 weeks' gestation was performed. Specimens were dissected en bloc, decalcified, embedded in paraffin wax, sectioned and fixed on glass slides, and stained. RESULTS: The pars begins to ossify at 12 to 13 weeks' gestation by endochondral ossification. The ossification center originates in the region of the pars in lower lumbar vertebrae, resulting in uneven distribution of trabeculation and cortication in this region. The ossification center arises at the end of the pedicle in upper lumbar segments giving rise to uniform trabeculation through the pars. CONCLUSIONS: Uneven distribution of isthmic ossification results in formation of a potential stress riser in the region of the pars in lower lumbar vertebrae, which could be susceptible to fatigue fracture.

Comparative evaluation of single-level closing-wedge vertebral osteotomies for the correction of fixed kyphotic deformity of the lumbar spine: a cadaveric study.

STUDY DESIGN: Anatomic study. OBJECTIVES: To compare spinal osteotomies with respect to obtainable correction and change in anterior height and distance of the spinal column and to describe a modification of the decancellation closing-wedge osteotomy to obtain further correction. SUMMARY OF BACKGROUND DATA: Fixed kyphotic deformity of the lumbar spine can cause difficulty with sitting, lying flat, and pain and can pose a risk to adjacent spinal cord and nerves as well as impair respiratory and abdominal function. Various corrective osteotomies have been described. Osteotomies involving decancellation and a closing wedge of the apical vertebra theoretically decrease the risk to anterior vascular structures. METHODS: Single-level vertebral osteotomies were performed on three groups of fresh-frozen human cadaveric lumbar spines. Group 1 underwent a conventional anterior opening-wedge/posterior closing-wedge osteotomy, Group 2 underwent a conventional decancellation posterior closing-wedge osteotomy, and Group 3 underwent our modified decancellation posterior closing-wedge osteotomy. Sagittal plane angulation as well as anterior height and distance of the spinal column were measured before and after osteotomy. RESULTS: The mean correction was 38 degrees for Group 1, 36 degrees for Group 2, and 49 degrees for Group 3. The mean change in anterior height and distance was 20 and 30 mm, respectively, for Group 1. For Groups 2 and 3 it was only 2-4 mm. CONCLUSIONS: The authors recommend single-level posterior decancellation procedures for correction of fixed kyphotic deformities of the thoracolumbar spine to decrease the risk to anterior neurovascular structures. An additional 10-13 degrees of correction can be obtained with the authors' modification.

Biomechanical analysis of fixation for vertically unstable sacroiliac dislocations with iliosacral screws and symphyseal plating.

OBJECTIVES: To examine the effects of various iliosacral screw configurations with and without symphyseal plating on sacroiliac (SI) motion and hemipelvis stability in the vertically unstable pelvic model. DESIGN: Biomechanical, human cadaver. SETTING: Level 1 trauma center. INTERVENTION: Hemipelvis and SI motion were analyzed on a Materials Testing System before and after creation of a vertically unstable APC III pelvic injury. Posterior fixation constructs consisted of iliosacral screws: (1). one into S1, (2). two into S1, or (3). one into S1 and one into S2. Results were obtained for all posterior constructs with and without a two-hole symphyseal plate. MAIN OUTCOME MEASUREMENT: Hemipelvis and SI motion with axial loading. RESULTS: There was no statistically significant difference between one or two iliosacral screws when hemipelvis rotational or linear displacement was examined at the SI joint. The two-hole symphyseal plate significantly increased the stability of the fixation construct in resisting linear displacement in all three planes. Without the symphyseal plate, an abnormal loading response was seen at the SI joint, resulting in paradoxical posterior translation and sagittal plane rotation. The addition of the plate restored the normal response, and anterior rotation and translation were observed as in the intact state. CONCLUSIONS: Anterior symphyseal plating for the vertically unstable hemipelvis significantly increases the stability of the fixation construct and restores the normal response of the hemipelvis to axial loading. A significant benefit to supplementary iliosacral screws in addition to a properly placed S1 iliosacral screw was not shown.

Compressed-air power tools in orthopaedic surgery: exhaust air is a potential source of contamination.

OBJECTIVES: To determine if the exhaust from surgical compressed-air power tools contains bacteria and if the exhaust leads to contamination of sterile surfaces. DESIGN: Bacteriologic study of orthopaedic power tools. SETTING: Level I trauma center operative theater. PATIENTS/PARTICIPANTS: None. INTERVENTION: Part I. Exhaust from two sterile compact air drills was sampled directly at the exhaust port. Part II. Exhaust from the drills was directed at sterile agar plates from varying distances. The agar plates represented sterile surfaces within the operative field. Part III. Control cultures. A battery-powered drill was operated over open agar plates in similar fashion as the compressed-air drills. Agar plates left open in the operative theater served as controls to rule out atmospheric contamination. Random cultures were taken from agar plates, gloves, drills, and hoses. MAIN OUTCOME MEASUREMENT: Incidence of positive cultures. RESULTS: In Part I, all filters from both compressed-air drill exhausts were culture negative ( = 0.008). In Part II, the incidence of positive cultures for air drills number one and number two was 73% and 82%, respectively. The most commonly encountered organisms were, coagulase-negative Staphylococcus, and Micrococcus species. All control cultures from agar plates, battery-powered drill, gloves, and hoses were negative ( < 0.01). CONCLUSIONS: Exhaust from compressed-air power tools in orthopaedic surgery may contribute to the dissemination of bacteria onto the surgical field. We do not recommend the use of compressed-air power tools that do not have a contained exhaust.

Electromagnetic field-based image-guided spine surgery part one: results of a cadaveric study evaluating lumbar pedicle screw placement.

STUDY DESIGN: Human cadaveric. OBJECTIVES: Compare the accuracy of electromagnetic field (EMF)-based image-guided lumbar pedicle screw insertion to conventional techniques using anatomic landmarks, and fluoroscopy. BACKGROUND: Image-guided surgical systems that aid in spinal instrumentation seek to minimize radiation exposure and improve accuracy. EMF tracking-based image-guidance was developed in the hopes of eliminating line-of-sight restrictions seen with other systems. MATERIALS AND METHODS: Sixteen fresh-frozen human cadavers were randomly allocated into three groups. Pedicle screws were inserted from L1 to L5 using only anatomic landmarks in group 1, fluoroscopy in group 2, and image-guidance in group 3. Insertion and total fluoroscopic time were recorded. Anatomic dissections were performed to assess screw placement. RESULTS: Accuracy was 83%, 78%, and 95% for groups 1, 2, and 3, respectively. However, image-guided pedicle screw placement resulted in a 5% critical perforation rate whereas anatomic and fluoroscopic placement resulted in a 15% and 22% critical perforation rate, respectively. The average degree of perforation was 1.5 mm with image guidance, and 3.8 mm with fluoroscopic guidance (P < 0.05). Fluoroscopy time and insertion time per screw were not improved using image guidance. CONCLUSIONS: Our study has shown that when EMF tracking was used for image-guided lumbar pedicle screw placement, accuracy was improved and the incidence and degree of cortical perforations that may place neurovascular structures at risk was also reduced. Current system requirements for set-up and image acquisition, however, do add time to the procedure, and when factored in, do not yet result in a decrease in the use of fluoroscopy or screw insertion time.

Electromagnetic field-based image-guided spine surgery part two: results of a cadaveric study evaluating thoracic pedicle screw placement.

STUDY DESIGN: Human cadaveric. OBJECTIVES: Compare the accuracy of electromagnetic field (EMF)-based image-guided thoracic pedicle screw insertion to conventional techniques using anatomic landmarks and fluoroscopy. BACKGROUND: Image-guided surgical systems that aid in spinal instrumentation seek to minimize radiation exposure and improve accuracy. EMF image guidance was developed as an alternative to optical tracking to eliminate potential line of sight issues. MATERIALS AND METHODS: Four fresh-frozen human cadavers were randomly allocated into two groups. Pedicle screws were inserted from T1 to T12 using anatomic landmarks and fluoroscopy in group 1 and image guidance in group 2. Insertion and fluoroscopy time were recorded. Anatomic dissections were performed to assess screw placement. RESULTS: Image guidance placed 92% of thoracic pedicle screws safely, and conventional fluoroscopy placed 90% safely. The average degree of perforation was 2.4 mm with conventional fluoroscopy and 1.7 mm with image guidance (P = 0.055). Fluoroscopic time per screw was 5.9 seconds for conventional fluoroscopy and 3.6 seconds for image guidance (P = 0.045). Insertion time per screw was 4.35 minutes for conventional fluoroscopy and 2.98 minutes for image guidance (P = 0.007). However, when set-up time and image capture time were taken into account, the total insertion time per screw was not significantly different between the two groups. CONCLUSIONS: Our study has shown that EMF image-guided thoracic pedicle screw placement results in a similar incidence of safely placed screws as does conventional fluoroscopy. When set-up time and image-capture time were factored in for image guidance, the average time to insert a pedicle screw was equal for both techniques. The use of EMF image guidance significantly reduced fluoroscopic time and thus radiation exposure per screw compared with conventional fluoroscopic techniques.