Reliability of computer-assisted periacetabular osteotomy using a minimally invasive approach

Background

Periacetabular osteotomy (PAO) is the treatment of choice for younger patients with developmental hip dysplasia. The procedure aims to normalize the joint configuration, reduce the peak-pressure, and delay the development of osteoarthritis. The procedure is technically demanding and no previous study has validated the use of computer navigation with a minimally invasive transsartorial approach.

Methods

Computer-assisted PAO was performed on ten patients. Patients underwent pre- and postoperative computed tomography (CT) scanning with a standardized protocol. Preoperative preparation consisted of outlining the lunate surface and segmenting the pelvis and femur from CT data. The Biomechanical Guidance System was used intra-operatively to automatically calculate diagnostic angles and peak-pressure measurements. Manual diagnostic angle measurements were performed based on pre- and postoperative CT. Differences in angle measurements were investigated with summary statistics, intraclass correlation coefficient, and Bland–Altman plots. The percentage postoperative change in peak-pressure was calculated.

Results

Intra-operative reported angle measurements show a good agreement with manual angle measurements with intraclass correlation coefficient between 0.94 and 0.98. Computer navigation reported angle measurements were significantly higher for the posterior sector angle (\(1.65^{\circ }\), \(p=0.001\)) and the acetabular anteversion angle (\(1.24^{\circ }\), \(p=0.004\)). No significant difference was found for the center-edge (\(p=0.056\)), acetabular index (\(p=0.212\)), and anterior sector angle (\(p=0.452\)). Peak-pressure after PAO decreased by a mean of 13% and was significantly different (\(p=0.008\)).

Conclusions

We found that computer navigation can reliably be used with a minimally invasive transsartorial approach PAO. Angle measurements generally agree with manual measurements and peak-pressure was shown to decrease postoperatively. With further development, the system will become a valuable tool in the operating room for both experienced and less experienced surgeons performing PAO. Further studies with a larger cohort and follow-up will allow us to investigate the association with peak-pressure and postoperative outcome and pave the way to clinical introduction.

     

Peripheral bronchial identification on chest CT using unsupervised machine learning

Purpose

To automatically identify small- to medium-diameter bronchial segments distributed throughout the lungs.

Methods

We segment the peripheral pulmonary vascular tree and construct cross-sectional images perpendicular to the lung vasculature. The bronchi running with pulmonary arteries appear as concentric rings, and potential center points that lie within the bronchi are identified by looking for circles (using the circular Hough transform) and rings (using a novel variable ring filter). The number of candidate bronchial center points are further reduced by using agglomerative hierarchical clustering applied to the points represented with 18 features pertaining to their 3D position, orientation and appearance of the surrounding cross-sectional image. Resulting clusters corresponded to bronchial segments. Parameters of the algorithm are varied and applied to two experimental data sets to find the best values for bronchial identification. The optimized algorithm was then applied to a further 21 CT studies obtained using two different CT vendors.

Results

The parameters that result in the most number of true positive bronchial center points with > 95% precision are a tolerance of 0.15 for the hierarchical clustering algorithm and a threshold of 75 HU with 10 spokes for the ring filter. Overall, the performance on all 21 test data sets from CT scans from both vendors demonstrates a mean number of 563 bronchial points detected per CT study, with a mean precision of 96%. The detected points across this group of test data sets are relatively uniformly distributed spatially with respect to spherical coordinates with the origin at the center of the test imaging data sets.

Conclusion

We have constructed a robust algorithm for automatic detection of small- to medium-diameter bronchial segments throughout the lungs using a combination of knowledge-based approaches and unsupervised machine learning. It appears robust over two different CT vendors with similar acquisition parameters.

     

AR in VR: assessing surgical augmented reality visualizations in a steerable virtual reality environment

Purpose 

Augmented reality (AR) has emerged as a promising approach to support surgeries; however, its application in real world scenarios is still very limited. Besides sophisticated registration tasks that need to be solved, surgical AR visualizations have not been studied in a standardized and comparative manner. To foster the development of future AR applications, a steerable framework is urgently needed to rapidly evaluate new visualization techniques, explore their individual parameter spaces and define relevant application scenarios.

Methods 

Inspired by its beneficial usage in the automotive industry, the underlying concept of virtual reality (VR) is capable of transforming complex real environments into controllable virtual ones. We present an interactive VR framework, called Augmented Visualization Box (AVB), in which visualizations for AR can be systematically investigated without explicitly performing an error-prone registration. As use case, a virtual laparoscopic scenario with anatomical surface models was created in a computer game engine. In a study with eleven surgeons, we analyzed this VR setting under different environmental factors and its applicability for a quantitative assessment of different AR overlay concepts.

Results 

According to the surgeons, the visual impression of the VR scene is mostly influenced by 2D surface details and lighting conditions. The AR evaluation shows that, depending on the visualization used and its capability to encode depth, 37% to 91% of the experts made wrong decisions, but were convinced of their correctness. These results show that surgeons have more confidence in their decisions, although they are wrong, when supported by AR visualizations.

Conclusion 

With AVB, intraoperative situations are realistically simulated to quantitatively benchmark current AR overlay methods. Successful surgical task execution in an AR system can only be facilitated if visualizations are customized toward the surgical task.

     

Robust extraction for low-contrast liver tumors using modified adaptive likelihood estimation

Purpose

Liver tumor extraction is essential for liver ablation surgery planning and treatment. For accurate and robust tumor segmentation, we propose a semiautomatic method using adaptive likelihood classification with modified likelihood model.

Methods

First, a minimal ellipse (or quasi-ellipsoid) that encloses a liver tumor is generated for initialization. Then, a hybrid intensity likelihood modification based on nonparametric density estimation is proposed to enhance local likelihood contrast and reduce its inhomogeneity. A prior elliptical (or quasi-ellipsoid) shape constraint is directly integrated into the likelihood to further prevent leakage of the algorithm into adjacent tissues with similar intensity. Finally, an adaptive likelihood classification is proposed for accurate segmentation of tumors with low contrast, high noise or heterogeneous densities.

Results

Experiments were performed on 3Dircadb and LiTS datasets. The average volumetric overlap errors of the 3Dircadb and LiTS datasets were 27.05 and 35.72%, respectively. The algorithm’s robustness was validated by comparing results of 5 operators with multiple selections on different tumors.

Conclusions

The proposed method achieved good results in different tumors, even in low-contrast tumors with blurred boundaries. Reliable results can still be achieved over different initializations by different operators using the proposed method.

     

Outcomes following cardiopulmonary resuscitation in an emergency department of a low- and middle-income country

Background

Cardiopulmonary resuscitation (CPR) is a key component of emergency care following cardiac arrest. A better understanding of factors that influence CPR outcomes and their prognostic implications would help guide care. A retrospective analysis of 800 adult patients that sustained an in- or out-of-hospital cardiac arrest and underwent CPR in the emergency department of a tertiary care facility in Karachi, Pakistan, between 2008 and 15 was conducted.

Methods

Patient demographics, clinical history, and CPR characteristics data were collected. Logistic regression model was applied to assess predictors of return of spontaneous circulation and survival to discharge. Analysis was conducted using SPSS v.21.0.

Results

Four hundred sixty-eight patients met the study’s inclusion criteria, and overall return of spontaneous circulation and survival to discharge were achieved in 128 (27.4%) and 35 (7.5%) patients respectively. Mean age of patients sustaining return of spontaneous circulation was 52 years and that of survival to discharge was 49 years. The independent predictors of return of spontaneous circulation included age ≤?49 years, witnessed arrest, ≤?30 min interval between collapse-to-start, and 1–4 shocks given during CPR (aOR (95% CI) 2.2 (1.3–3.6), 1.9 (1.0–3.7), 14.6 (4.9–43.4), and 3.0 (1.4–6.4) respectively), whereas, age ≤?52 years, bystander resuscitation, and initial rhythm documented (pulseless electrical activity and ventricular fibrillation) were independent predictors of survival to discharge (aOR (95% CI) 2.5 (0.9–6.5), 1.4 (0.5–3.8), 5.3 (1.5–18.4), and 3.1 (1.0–10.2) respectively).

Conclusion

Our study notes that while the majority of arrests occur out of the hospital, only a small proportion of those arrests receive on-site CPR, which is a key contributor to unfavorable outcomes in this group. It is recommended that effective pre-hospital emergency care systems be established in developing countries which could potentially improve post-arrest outcomes. Younger patients, CPR initiation soon after arrest, presenting rhythm of pulseless ventricular tachycardia and ventricular fibrillation, and those requiring up to four shocks to revive are more likely to achieve favorable outcomes.

     

Injury Prevention in Baseball: from Youth to the Pros

Purpose of Review

This review examines recent literature on injury epidemiology and prevention in the sport of baseball from youth to professional levels.

Recent Findings

Overuse is the predominant mechanism of injury in youth baseball players. Newer stretching and exercise protocols may help prevent these injuries. At the professional level, however, overuse has not been proven to correlate with increased injury incidence, but pitch counts are still monitored. There continues to be a rise in operations performed for baseball-related injuries, including ulnar collateral ligament (UCL) reconstruction, particularly in younger athletes. As the level of play increases, there is significant loss of participation due to injuries, such as the UCL in the upper extremity and the hamstrings in the lower extremity.

Summary

Baseball is a widely popular sport, which has led to a focus on injury epidemiology and prevention. While the majority of research regarding baseball injuries focuses on pitchers, fielders and catchers are also at risk. In an attempt to decrease non-contact injuries in the upper and lower extremities, stretching and strengthening exercises are vitally important. Because injury profiles demonstrate significant variability from youth to professional baseball, unique prevention strategies are likely necessary at each level. More research is needed to develop and validate appropriately targeted injury prevention programs.

     

Nonreconstruction Options for Treating Medial Ulnar Collateral Ligament Injuries of the Elbow in Overhead Athletes

Purpose of Review

This review aims to describe the nonreconstructive options for treating ulnar collateral ligament (UCL) injuries ranging from nonoperative measures, including physical therapy and biologic injections, to ligament repair with and without augmentation.

Recent Findings

Nonoperative options for UCL injuries include guided physical therapy and biologic augmentation with platelet-rich plasma (PRP). In some patients, repair of the UCL has shown promising return to sport rates by using modern suture and suture anchor techniques. Proximal avulsion injuries have shown the best results after repair. Currently, there is growing interest in augmentation of UCL repair with an internal brace.

Summary

The treatment of UCL injuries involves complex decision making. UCL reconstruction remains the gold standard for attritional injuries and complete tears, which occur commonly in professional athletes. However, nonreconstructive options have shown promising results for simple avulsion or partial thickness UCL injuries. Future research comparing reconstructive versus nonreconstructive options is necessary.

     

Treatment of Partial Thickness Rotator Cuff Tears in Overhead Athletes

Purpose of Review

To review the etiology, classification, presentation, evaluation, treatment strategy, and outcomes in overhead athletes with partial thickness rotator cuff tears.

Recent Findings

Despite advances in surgical repair techniques, return to play following surgical repair of partial rotator cuff tears remains modest at best.

Summary

Overhead athletes may be particularly prone to rotator cuff pathology due to the supraphysiological strains within the tendon during the throwing motion, as well as mechanical stress with contact between the undersurface of the rotator cuff and the glenoid. The true prevalence of partial tears may be underestimated given the high incidence of asymptomatic tears. Both dynamic ultrasound and enhanced contrast MRI have improved our understanding of this pathology. For most overhead athletes, nonoperative management is the most common course. Despite advances in imaging, diagnosis, and surgical techniques, our ability to return these patients to their elite level is modest at best when nonoperative management fails and surgical treatment is performed. If a surgical route is needed, debridement alone is the most frequent procedure given concerns of over constraint and poor return to play with surgical repair of the partial thickness rotator cuff tear.

     

Return to Throwing after Shoulder or Elbow Injury

Purpose of review

Throwing places high demands on the human body, and specific characteristics are developed over time unique to these athletes. When returning to throw after injury, it is important to follow a criterion-based progression that allows the body to be prepared appropriately for the stresses that throwing will require. There is currently a void in the literature for criteria-based progression that helps these athletes return to the highest level of play.

Recent findings

As injury rates continue to rise in baseball, there is increased evidence showing contributions of the core and lower extremity to the baseball pitch. There is also additional data showing pitcher specific characteristics such as range of motion and scapular position in this unique population. The rehab professional should take into account every phase of the pitch starting from balance through ball release when designing a comprehensive return-to-throwing program.

Summary

Returning an athlete back to a throwing sport can be an overwhelming task. The rehabilitation specialist must have a sound understanding of the throwing motion as well as any biomechanical implications on the body, contributions throughout the kinetic chain, range of motion, and strength characteristics specific to the thrower as well as proper tissue loading principles. It is important that these athletes are not progressed too quickly through their programs and that a criteria-based progression is followed. They should have normalized range of motion, strength, and scapular mechanics, followed by a sound plyometric progression. Once this is achieved, they are advanced to an interval throwing program with increasing distance, effort, and volume which should be tracked for workload, making sure they do not throw more than their body is prepared for.