ABSTRACT
BACKGROUND: Different hexapod-based external fixators are increasingly used to treat bone deformities and fractures. Accuracy has not been measured sufficiently for all models. METHODS: An infrared tracking system was applied to measure positioning maneuvers with a motorized Precision Hexapod® fixator, detecting three-dimensional positions of reflective balls mounted in an L-arrangement on the fixator, simulating bone directions. By omitting one dimension of the coordinates, projections were simulated as if measured on standard radiographs. Accuracy was calculated as the absolute difference between targeted and measured positioning values. RESULTS: In 149 positioning maneuvers, the median values for positioning accuracy of translations and rotations (torsions/angulations) were below 0.3 mm and 0.2° with quartiles ranging from -0.5 mm to 0.5 mm and -1.0° to 0.9°, respectively. CONCLUSIONS: The experimental setup was found to be precise and reliable. It can be applied to compare different hexapod-based fixators. Accuracy of the investigated hexapod system was high.
Subject(s)
Equipment Failure Analysis/instrumentation , External Fixators , Imaging, Three-Dimensional/instrumentation , Robotic Surgical Procedures/instrumentation , Biomechanical Phenomena , Equipment Design , Equipment Failure Analysis/methods , Imaging, Three-Dimensional/methods , Motion , Reproducibility of Results , Robotic Surgical Procedures/methods , Sensitivity and SpecificityABSTRACT
BACKGROUND AND HYPOTHESIS: Nonoperative treatment is standard for most diaphyseal clavicle fractures, but recent studies have demonstrated improved outcomes with operative treatment of displaced fractures. The objectives of this diagnostic study were to assess agreement of orthopaedic surgeons regarding their treatment preferences for diaphyseal clavicle fractures and to compare them with recent recommendations. Interobserver and intraobserver agreement in treatment decisions were hypothesized to be only slight. METHODS: Anonymized case vignettes of 50 acute diaphyseal clavicle fractures including medical history, physical examination findings, and radiographs were independently reviewed by 32 orthopaedic surgeons from the United States. Four treatment options were offered and decisions were compared with current treatment recommendations. Interobserver agreement was calculated using Fleiss' kappa coefficient. Average intraobserver agreement for surgeons who completed a retest review (minimum interval of 8 weeks) was calculated. RESULTS: Thirty-two surgeons completed the first round of reviewing and 27 completed the retest (mean interval, 22 weeks). Interobserver agreement was overall fair (kappa = 0.36) and moderate (kappa = 0.56) when operative options were compared with nonoperative options. Median intraobserver agreement was 74% for the 4 treatment options offered and 84% in deciding on operative vs. nonoperative means. Concordance with recent recommendations for operative vs. nonoperative treatment was seen in 91% of decisions (median). DISCUSSION AND CONCLUSIONS: Recent recommendations appear to have been adopted by a selected subgroup of U.S. orthopaedic surgeons, showing a surprisingly high median concordance of 91% in this study. However, only fair to moderate interobserver and intraobserver agreement was present, leaving potential for improvement.
