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Background: Symptomatic leg length discrepancies (LLDs) are a significant complication after total hip arthroplasty. Many surgeons incorporate an intraoperative anteroposterior pelvis radiograph, to help prevent LLD; however, obtaining a high-quality radiograph is often difficult. The purpose of this study is to evaluate the accuracy and reliability of estimating LLD using different radiographic reference landmarks on suboptimal anteroposterior pelvis radiographs. Material and methods: We obtained 2 pelvis Sawbones models with attached femurs and created a true shortening of the left femur of the experimental model by 7 mm. We then obtained a series of radiographs manipulating each model in standardized increments for a total of 66 different permutations of suboptimal radiographs. Each radiograph was evaluated for LLD by 2 separate orthopedic surgeons using reference lines bisecting the following anatomic landmarks: ischial tuberosities, acetabular teardrops, obturator foramina, sacroiliac joints, and the femoral heads, to the lesser trochanters. The accuracy and reliability of each line were then analyzed. Results: The obturator foramina line yielded the most reliable LLD estimates with an intraclass correlation coefficient of 0.939. This reference line was also the most accurate, with an average difference of 1.5 mm from the true LLD (P < .001), with 95% confidence to be within 1.8 mm. Conclusion: The obturator foramen reference line on an intraoperative radiograph is an accurate and reliable tool that should be utilized by joint replacement surgeons to estimate LLD even if the radiograph is suboptimal. This estimate is reliably reproduced among multiple observers and puts the estimate within 1.8 mm of a true LLD.
ABSTRACT
[This retracts the article DOI: 10.7759/cureus.7206.].
ABSTRACT
PURPOSE: Tibia shaft fractures account for 15% of all pediatric fractures. These fractures are often treated nonoperatively with closed reduction and long leg casting. In children treated nonoperatively, refracture can cause significant frustration to both the patient and their family in addition to a delay in resuming normal activities for several months. The purpose of this study was to investigate the rate of refracture of tibia shaft fractures treated nonoperatively at our institution. METHODS: We performed a retrospective chart review of pediatric patients at one institution with the diagnosis of a tibia shaft fracture who were treated nonoperatively between January 1, 2000 and December 31, 2016. Exclusion criteria included those without complete retrievable radiographs or without radiographic confirmation of healed fracture. Patients who sustained a proximal or distal metaphysical tibia fracture or a toddler fracture were also excluded. Additionally, those with less than three months of clinic follow-up or an underlying metabolic bone disease were excluded. Data such as age, sex, body mass index, mechanism of injury, location of fracture, initial displacement, angulation, treatment, length of immobilization, and complications were recorded. The primary outcome for our study was the presence of refracture. Refracture was defined as a repeat fracture of the tibia at the same location within 18 months of the original fracture. RESULTS: A total of 64 patients met the inclusion criteria and were included in the study. Of the 64 patients, only one patient sustained a refracture. The refracture occurred eight months after the initial injury and required operative intervention. This rate of refracture is equated to roughly 1.5%. CONCLUSION: Conservative management of closed tibia shaft fractures with casting is an ideal treatment for pediatric fractures. Conservative management allows for avoidance of surgical intervention and low refracture rates. This study provides support regarding the adequacy of conservative management with limited complications. Although the rate of refracture still exists, patients and families should be counseled that the rate of healing without complications is about 98.5%.
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PURPOSE: The use of dynamic arcs for delivery of stereotactic body radiation therapy (SBRT) on Cyberknife is investigated, with a view to improving treatment times. This study investigates the required modeling of robot and multileaf collimator (MLC) motion between control points in the trajectory and then uses this to develop an optimization method for treatment planning of a dynamic arc with Cyberknife. The resulting plans are compared in terms of dose-volume histograms and estimated treatment times with those produced by a conventional beam arrangement. METHODS: Five SBRT patient cases (prostate A - conventional, prostate B - brachytherapy-type, lung, liver, and partial left breast) were retrospectively studied. A suitable arc trajectory with control points spaced at 5° was proposed and treatment plans were produced for typical clinical protocols. The optimization consisted of a fluence optimization, segmentation, and direct aperture optimization using a gradient descent method. Dose delivered by the moving MLC was either taken to be the dose delivered discretely at the control points or modeled using effective fluence delivered between control points. The accuracy of calculated dose was assessed by recalculating after optimization using five interpolated beams and 100 interpolated apertures between each optimization control point. The resulting plans were compared using dose-volume histograms and estimated treatment times with those for a conventional Cyberknife beam arrangement. RESULTS: If optimization is performed based on discrete doses delivered at the arc control points, large differences of up to 40% of the prescribed dose are seen when recalculating with interpolation. When the effective fluence between control points is taken into account during optimization, dosimetric differences are <2% for most structures when the plans are recalculated using intermediate nodes, but there are differences of up to 15% peripherally. Treatment plan quality is comparable between the arc trajectory and conventional body path. All plans meet the relevant clinical goals, with the exception of specific structures which overlap with the planning target volume. Median estimated treatment time is 355 s (range 235-672 s) for arc delivery and 675 s (range 554-1025 s) for conventional delivery. CONCLUSIONS: The method of using effective fluence to model MLC motion between control points is sufficiently accurate to provide for accurate inverse planning of dynamic arcs with Cyberknife. The proposed arcing method produces treatment plans with comparable quality to the body path, with reduced estimated treatment delivery time.
