Evaluation of acetabular fractures with two- and three-dimensional CT

Interobserver and intraobserver agreement for Letournel acetabular fracture classification system using 3-dimensional printed solid models

BACKGROUND

Acetabular fractures pose diagnostic and surgical challenges. They are classified using the Judet-Letournel system, which is based solely on X-ray. However, computed tomography (CT) imaging is now more widely utilized in diagnosing these injuries. The emergence of 3-dimensional (3-D) printing technology in varying orthopedic fields has provided surgeons a solid model that improves their spatial understanding of complex fractures and ability to plan pre-operatively.

AIM

To evaluate the reliability of the Judet-Letournel classification system of acetabular fractures, when using either CT imaging or 3-D printed models.

METHODS

Seven patients with acetabular fractures underwent pelvic CT imaging, which was then used to create solid, 3-D printed models. Eighteen orthopaedic trauma surgeons responded to questionnaires regarding fracture classification and preferred surgical approach. The same questionnaire was completed using only CT imaging, and two weeks later, using only 3-D printed models. The inter- and intra-observer agreement rates were then analyzed.

RESULTS

Inter-observer agreement rates based on CT imaging or 3-D printed models were moderate for fracture classification: κ = 0.44, κ = 0.55, respectively (P < 0.001) and fair for preferred surgical approach: κ = 0.34, κ = 0.29, respectively (P < 0.005). Intra-observer agreement rates for fracture classification and preferred surgical approach comparing CT imaging or 3-D printed models were moderate: κ = 0.48, κ = 0.41, respectively. No significant difference in intra-observer agreement was detected when comparing orthopedic pelvic specialists to general orthopedic traumatologists.

CONCLUSION

The Judet-Letournel classification demonstrated only moderate rates of agreement. The use of 3-D printed models increased the inter-observer agreement rates with respect to fracture classification, but decreased it with respect to the preferred surgical approach. This study highlights the role of 3-D printed models in acetabular fractures by improving spatial understanding of these complex injuries, thus providing more reliable fracture diagnoses and alternative viewpoints for pre-operative planning.

Imaging Acetabular Fractures

Acetabular fractures are encountered by radiologists in a wide spectrum of practice settings. The radiologist's value in the acute and long-term management of acetabular fractures is augmented by familiarity with systematic computed tomography-based algorithms that streamline and simplify Judet-Letournel fracture typing, together with an appreciation of the role of imaging in initial triage, operative decision making, postoperative assessment, prognostication, and evaluation of complications. The steep increase in incidence of acetabular fractures in the elderly over the past several decades places special emphasis on familiarity with geriatric fracture patterns.

Does 3DMR provide equivalent information as 3DCT for the pre-operative evaluation of adult Hip pain conditions of femoroacetabular impingement and Hip dysplasia?

OBJECTIVE:

Femoroacetabular impingement (FAI) and hip dysplasia (HD) are frequently evaluated by isotropic CT (3DCT) for preoperative planning at the expense of radiation. The aim was to determine if isotropic MRI (3DMR) imaging can provide similar quantitative and qualitative morphological information as 3DCT.

METHODS:

25 consecutive patients with a final diagnosis of FAI or HD were retrospectively selected from December 2016-December 2017. Two readers (R1, R2) performed quantitative angular measurements on 3DCT and 3DMR, blinded to the diagnosis and each other's measurements. 3DMR and 3DCT of the hips were qualitatively and independently evaluated by a radiologist (R3), surgeon (R4), and fellow (R5). Interobserver and intermodality comparisons were performed.

RESULTS:

The ICC was good to excellent for all measurements between R1 and R2 (ICC:0.60-0.98) and the majority of intermodality measurements for R1 and R2. Average inter-reader and inter-modality PABAK showed good to excellent agreement for qualitative reads. On CT, all alpha angles (AA) were significantly lower in dysplasia patients than in cam patients (p < 0.05). All lateral center-edge angle (LCEA) were significantly lower in dysplasia than in cam patients (p < 0.05). On MR, AA at 12, 1, and 2 o'clock, and LCEA at center were significantly lower in dysplasia patients than in cam patients (p < 0.05).

CONCLUSION:

3DMR offers similar qualitative and quantitative analysis as 3DCT in adult painful hip conditions.

ADVANCES IN KNOWLEDGE:

3DMR has good potential to replace 3DCT and serve as a one-stop modality for bone and soft tissue characterizations in the pre-operative evaluation of FAI and HD.

Biomechanical analysis of the fixation systems for anterior column and posterior hemi-transverse acetabular fractures

Objective

The aim of this study was to evaluate the biomechanical properties of common fixation systems for complex acetabular fractures.

Methods

A finite element (FE) pelvic model with anterior column and posterior hemi-transverse acetabular fractures was created. Three common fixation systems were used to fix the posterior wall acetabular fractures: 1. Anterior column plate combined with posterior column screws (group I), 2. Anterior column plate combined with quadrilateral area screws (group II) and 3. Double-column plates (group III). And 600 N, representing the body weight, was loaded on the upper surface of the sacrum to simulate the double-limb stance. The amounts of total and relative displacements were compared between the groups.

Results

The total amount of displacement was 2.76 mm in group II, 2.81 mm in group III, and 2.83 mm in group I. The amount of relative displacement was 0.0078 mm in group II, 0.0093 mm in group III and 0.014 mm in group I.

Conclusion

Our results suggested that all fixation systems enhance biomechanical stability significantly. Anterior column plate combined with quadrilateral area screws has quite comparable results to double column plates, they were superior to anterior column plate combined with posterior screws.

CT-generated radiographs in patients with pelvic ring injury: can they be used in lieu of plain radiographs?

Background

Pelvic ring injury classification traditionally is made using plain radiographs. Recent studies suggest that computed tomography (CT)-generated images have higher diagnostic accuracy than plain films for the classification of acetabular fractures. However, similar studies have not been performed for pelvic ring injuries. The purpose of this study was to compare CT-generated and plain radiographs in terms of the ability of surgeons at different experience levels to identify pelvic injury type.

Methods

CT-generated and plain radiograph image sets were created from 15 pelvic ring injury patients with known classification morphology. Three groups, each consisting of three orthopaedic surgeons representing different levels of expertise, viewed these image sets and recorded their diagnoses. These diagnoses were compared to the gold standard findings of the treating physician and to each other.

Results

Overall, there was a significantly improved ability to correctly classify pelvic ring injury type by CT-generated radiographs as compared to plain radiographs (p < 0.01). However, analysis of the groups revealed that this difference was limited to the less experienced groups (p < 0.05).

Conclusions

CT-generated radiographs are diagnostically beneficial for less experienced surgeons and at least as good as conventional plain radiographs for experienced surgeons in classifying pelvic ring injuries. Therefore, CT-generated radiographs may be clinically valuable: sparing the patient additional radiation exposure and discomfort by avoiding the reordering of plain radiographs when the initial studies are of poor quality, as well as serving as a possible alternative for supplemental initial injury plain radiographic views.

Acetabular fractures: what radiologists should know and how 3D CT can aid classification

Correct recognition, description, and classification of acetabular fractures is essential for efficient patient triage and treatment. Acetabular fractures may result from high-energy trauma or low-energy trauma in the elderly. The most widely used acetabular fracture classification system among radiologists and orthopedic surgeons is the system of Judet and Letournel, which includes five elementary (or elemental) and five associated fractures. The elementary fractures are anterior wall, posterior wall, anterior column, posterior column, and transverse. The associated fractures are all combinations or partial combinations of the elementary fractures and include transverse with posterior wall, T-shaped, associated both column, anterior column or wall with posterior hemitransverse, and posterior column with posterior wall. The most unique fracture is the associated both column fracture, which completely dissociates the acetabular articular surface from the sciatic buttress. Accurate categorization of acetabular fractures is challenging because of the complex three-dimensional (3D) anatomy of the pelvis, the rarity of certain acetabular fracture variants, and confusing nomenclature. Comparing a 3D image of the fractured acetabulum with a standard diagram containing the 10 Judet and Letournel categories of acetabular fracture and using a flowchart algorithm are effective ways of arriving at the correct fracture classification. Online supplemental material is available for this article.

Utility of three-dimensional computed tomography for the surgical management of rib fractures

BACKGROUND

Surgical stabilization of flail chest is increasingly recognized as a valid approach to improve pulmonary mechanics in selected trauma patients. The use of two-dimensional (2D) computed tomography (CT) has become almost universal in the assessment of blunt chest trauma and multiple rib fractures. We hypothesized that three-dimensional (3D) CT adds valuable information to the preoperative plan for fixation of rib fractures.

METHODS

Using a retrospective cohort of 35 consecutive adult patients with flail chest requiring surgery, we evaluated the intraobserver and interobserver reliability of plain radiographs, 2D CT and 3D CT, for the identification of rib fractures and identified how often the surgical plan changed with the addition of the information provided by the 3D CT. Two fellowship-trained orthopedic trauma surgeons who regularly operate on rib fractures in their clinical practice and were not involved in the treatment of the study population evaluated the radiographic data.

RESULTS

Intraobserver and interobserver reliability was excellent for both 2D CT and 3D CT and was the highest for 2D CT. Overall, 2D CT had the highest diagnostic accuracy for detecting rib fractures as compared with plain radiographs and 3D CT. However, 3D CT changed the surgical tactic in 65.7% of the cases.

CONCLUSION

We conclude that 3D CT is not as accurate as 2D CT for rib fracture diagnostic purposes; it seems to be an important tool for the preoperative planning of rib fracture fixation.

LEVEL OF EVIDENCE

Diagnostic study, level II.

CT-generated radiographs in obese patients with acetabular fractures: can they be used in lieu of plain radiographs?

BACKGROUND

Acetabular fracture diagnosis is traditionally made with AP and oblique pelvic plain radiographs. Obesity may impair diagnostic accuracy of plain radiographs. New CT reconstruction algorithms allow for simulated radiographs that may eliminate the adverse imaging effects of obesity.

QUESTIONS/PURPOSES

In obese patients with acetabular fractures, we compared CT-generated and plain radiographs in terms of (1) ability to classify fracture type, (2) agreement in fracture classification, and (3) surgeon performance at different experience levels.

METHODS

CT-generated and plain radiograph image sets were created for 16 obese (BMI>35) patients with 17 acetabular fractures presenting from 2009 to 2011. Three orthopaedic trauma attending physicians, three senior residents, and three junior residents independently viewed these sets and recorded their diagnoses. These diagnoses were compared to the postoperative findings, which we defined as the gold standard for diagnosis. To assess intraobserver reliability, the same observers reviewed a rerandomized set 1 month later. We had 80% power to detect a 25% difference in the percentage of correctly classified fractures based on a post hoc sample size calculation and 80% power to detect a 0.10 difference in κ value based on both a priori and post hoc sample size calculations.

RESULTS

With the numbers available (153 observations in each image set, 51 for each of the three observer groups), we found no differences between CT-generated and plain radiographs, respectively, in terms of percentage of correct diagnoses for the observer groups (all observers: 54% versus 49%, p=0.48; attendings: 61% versus 59%, p=0.83; senior residents: 51% versus 53%, p=0.84; and junior residents: 49% versus 35%, p=0.16). Furthermore, agreement between CT-generated and plain radiographic fracture classifications was substantial (κ=0.67). Nonetheless, the attending and senior resident groups performed better in correctly classifying the fracture than the junior residents when using plain radiographs (p=0.01 and p=0.049, respectively). Performance was not different when comparing the attendings to the senior resident and junior groups or comparing the senior residents to the junior residents using CT-generated radiographs (p=0.32, p=0.22, and p=0.83, respectively).

CONCLUSIONS

CT-generated radiographs are as good as plain radiographs for experienced surgeons for classifying acetabular fractures in obese patients. CT-generated imaging may be valuable in both teaching and clinical settings, and it may spare the patient additional radiation exposure and discomfort.

LEVEL OF EVIDENCE

Level II, diagnostic study. See the Instructions for Authors for a complete description of levels of evidence.

The study of broken quadrilateral surface in fractures of the acetabulum

PURPOSE

Three-dimensional computerised tomography (3DCT) can provide comprehensive patho-anatomy of complex bone on a single image. Though important, the key articular quadrilateral [Q] surface has not been a part of the systems developed for classifying acetabulum fractures. The purpose of the study was to simplify the complexity of classification by the direct sign of the broken Q surface which lies opposite the entire floor of the acetabulum.

METHODS

The study reviewed 84 acetabular fractures using 3DCT images of the interior lateral view (IL) taken between June 2002 to December 2009. Fractures were traditionally classified using the anatomical disruption, plane of the fracture line breaking through or not through the bone column described by Judet and Letournel.

RESULTS

The 3D images clearly show the primary site of impaction acting on the acetabulum and the whole course of fracture. The image could not illustrate disruption of the lips of acetabulum and congruity of hip joints in 20 cases of wall (W) fracture. There were 30 transverse (T) fractures classified when the acetabulum was divided horizontally from front to back into upper and lower parts and 34 cases of column (C) fracture when the main vertical lines run and collide along the anterior and posterior column.

CONCLUSIONS

This study showed that the well-known complex fractures can be satisfactorily classified with the broad flat inner plane of the Q surface.

Value of 3-D CT in classifying acetabular fractures during orthopedic residency training

The complex anatomy of the pelvis and acetabulum have historically made classification and interpretation of acetabular fractures difficult for orthopedic trainees. The addition of 3-dimensional (3-D) computed tomography (CT) scan has gained popularity in preoperative planning, identification, and education of acetabular fractures given their complexity. Therefore, the authors examined the value of 3-D CT compared with conventional radiography in classifying acetabular fractures at different levels of orthopedic training. Their hypothesis was that 3-D CT would improve correct identification of acetabular fractures compared with conventional radiography.The classic Letournel fracture pattern classification system was presented in quiz format to 57 orthopedic residents and 20 fellowship-trained orthopedic traumatologists. A case consisted of (1) plain radiographs and 2-dimensional axial CT scans or (2) 3-D CT scans. All levels of training showed significant improvement in classifying acetabular fractures with 3-D vs 2-D CT, with the greatest benefit from 3-D CT found in junior residents (postgraduate years 1-3).Three-dimensional CT scans can be an effective educational tool for understanding the complex spatial anatomy of the pelvis, learning acetabular fracture patterns, and correctly applying a widely accepted fracture classification system.

Can computed tomography predict hip stability in posterior wall acetabular fractures?

BACKGROUND

In a pilot study, two-dimensional (2-D) CT assessment of posterior wall fracture fragments predicted hip stability with small fracture fragments and instability for large fracture fragments.

QUESTIONS/PURPOSES

To confirm the previous findings, we determined whether there is sufficient observer consistency and accuracy to predict hip stability in posterior wall acetabular fractures for this CT assessment method and assessed its ease of clinical use.

METHODS

We selected 10 fractures having variable characteristics with known clinical outcome and created three study participant groups, based on level of training, for evaluation. Each observer reviewed the CT scans from the 10 fractures and applied the method in two separate sessions, the second after at least a 1-month washout period.

RESULTS

Participants reported subjective ease in using the method, averaging 5 minutes (range, 3-11 minutes) for each assessment. Intraobserver and interobserver reliability were both greater than 0.80 regardless of the level of experience. Although sensitivity was 90%, specificity was only 61% after comparison with examination under anesthesia (EUA). Inappropriate nonoperative treatment would have occurred in 6% of cases and inappropriate operative treatment in 16%.

CONCLUSIONS

This method for assessing hip instability is reliable, reproducible, and easy to learn and use. However, as a diagnostic tool in the clinical setting, it is useful only for fractures involving greater than 50% of the posterior wall owing to limited accuracy. For fractures less than 50%, EUA should be performed to determine hip stability.

Acetabular fracture reductions in the obese patient

OBJECTIVES

To evaluate the radiographic and computed tomographic reduction qualities after acetabular fracture repair in obese and nonobese patients.

DESIGN

Retrospective review.

SETTING

University medical center.

PATIENTS/PARTICIPANTS

Two hundred forty-two patients were treated with open reduction internal fixation for displaced acetabular fractures. The nonobese group (Group 1) consisted of 149 patients and the obese group (Group 2) had 93 patients. A nonmorbidly obese group (Group 3 = 221 patients) and a morbidly obese group (Group 4 = 21 patients) were also created from the same patient population.

INTERVENTION

Operative repair of acetabular fractures.

MAIN OUTCOME MEASUREMENTS

Reductions on postoperative radiographs were classified as anatomic with less than 1 mm, imperfect with 2 to 3 mm, and poor with greater than 3 mm of residual displacement. On postoperative computed tomographic scans, reductions were considered nonanatomic with persistent gap or step displacements greater than or equal to 2 mm.

RESULTS

Anatomic radiographic reductions were achieved in 72% of the nonobese patients, 70% of the obese patients, 72% of the nonmorbidly obese patients, and 61% of the morbidly obese patients. (P = 0.379) On postoperative computed tomographic scans, an acceptable reduction was obtained in 47% of the nonobese patients, 44% of the obese patients, 47% of the nonmorbidly obese patients, and 31% of the morbidly obese patients. (P = 0.232).

CONCLUSIONS

Anatomic or satisfactory reductions can be similarly achieved in all classes of nonmorbidly obese patients who have sustained displaced acetabular fractures. In the morbidly obese, anatomic reductions may be more difficult to obtain.

Proposed guidelines for increasing the reliability and validity of Letournel classification system

The aim of this study was to improve the reliability of Letournel classification system using a guideline algorithm protocol. The study was conducted upon two groups of orthopaedic surgeons with different experience and was consisted of two observation sessions (A and B). In session A, every observer studied, with no instructions or guidelines, a particular set of acetabular fractures on AP and Judet oblique views. In session B the observers had to examine the same set of radiographs by taking into account a guideline algorithm protocol. The unweighted kappa coefficient was utilised to estimate the observers' agreement arising from the examination of the given X-rays. Finally, the agreement of the observers, related to the intraoperative diagnosis was estimated. The main finding of the herein study lies on the improvement of the agreement rate experienced within both groups, in session B over session A. It is reasonable to assume that the main reason behind this result is the provision of the guideline algorithm protocol in the second session. The total agreement rate was increased from 59.9% in session A to 72.1% in session B, (p value=0.0267). Our findings confirm the reliability of Letournel classification system and the proposed guideline algorithm protocol further improve the ability to classify the most complex acetabular fractures types.

Imaging of the acetabulum in the era of multidetector computed tomography

Acetabular fractures are often complex injuries and the result of high-energy trauma with associated injuries. Understanding and classification of these rare injuries using radiography can be difficult and are much facilitated by the addition of computed tomography (CT). The purpose of this paper is to briefly review some of the underlying physical principles and technical factors for multidetector CT (MDCT) and to describe its use and imaging findings in the evaluation of acetabular fractures. Using MDCT with two-dimensional multiplanar reformatted (MPR) images and three-dimensional volume rendered images, the supplemental oblique radiographic Judet views can be omitted. MDCT is now an indispensable tool in preoperative imaging of acetabular fractures and also in postoperative imaging in complicated cases. Not only is MDCT excellent for a general overview but also for detailed imaging of fracture extent, joint congruency, step-offs or gaps in the joint surface, and entrapped osteochondral fragments.

Classification of common acetabular fractures: radiographic and CT appearances

OBJECTIVE

Accurate characterization of acetabular fractures can be difficult because of the complex acetabular anatomy and the many fracture patterns. In this article, the five most common acetabular fractures are reviewed: both-column, T-shaped, transverse, transverse with posterior wall, and isolated posterior wall. Fracture patterns on radiography are correlated with CT, including multiplanar reconstruction and 3D surface rendering.

CONCLUSION

In the evaluation of the five most common acetabular fractures, assessment of the obturator ring, followed by the iliopectineal and ilioischial lines and iliac wing, for fracture allows accurate classification. CT is helpful in understanding the various fracture patterns.

Interobserver agreement for Letournel acetabular fracture classification with multidetector CT: are standard Judet radiographs necessary?

PURPOSE

To retrospectively evaluate interobserver agreement for Letournel acetabular fracture classification with radiography alone and multidetector computed tomography (CT) alone and to retrospectively assess whether standard Judet views lead to a change in the classification.

MATERIALS AND METHODS

Institutional review board approval was obtained; informed consent was not required for this HIPAA-compliant study, which included 101 imaging studies performed in 99 patients (78 male, 21 female; mean age, 43 years; age range, 15-86 years) with acetabular fractures. Two musculoskeletal radiologists independently classified the fractures with radiography alone and multidetector CT alone. Multiplanar reformatted and three-dimensional (3D) CT images were reviewed at a computer workstation. Readers were shown radiographs at the end of multidetector CT image reading to see if this would change the multidetector CT-based classification. kappa Values were calculated to assess interobserver agreement. For surgically treated patients, the McNemar test was used to compare the accuracy of readers' classifications. The reference standard was a combination of preoperative radiographic and multidetector CT image findings and intraoperative findings.

RESULTS

Interobserver agreement was moderate (kappa = 0.42) with radiography and substantial (kappa = 0.70) with multidetector CT. Multidetector CT classification was changed in two cases (one case for each reader) after standard Judet views were added. In 73 surgically treated patients, agreement with the surgeons' classification was higher with multidetector CT than with radiography (P < .01 for one reader, P = .06 for the other reader).

CONCLUSION

There is substantial interobserver agreement for Letournel acetabular fracture classification with multiplanar reformatted and 3D multidetector CT images. Standard Judet pelvic radiographs add little information for changing the multidetector CT classification.

Die postoperative Kontroll-CT nach Acetabulumfraktur

Fractures of the acetabulum are severe injuries of the hip joint. Exact preoperative management is necessary to make possible an anatomical reconstruction. Postoperative quality control is done best with computed tomography. Is the higher radiation exposure caused by this routine examination justified?During the 5 years from 1995 to 1999, a total of 154 patients with fractures of the acetabulum were examined postoperatively at our clinic using CT to control reconstruction, implant position and the remaining free fragments in the joint. Thirteen of these patients (8.4%) had to be re-operated after postoperative CT control. The causes of the re-operation were four cases of an intra-articular implant position, three of free fragments remaining in the joint, and in 6 patients showed inadequate reconstruction. The mean radiation exposure was 25 mGy per patient. The low mean age of the patients and the long lasting consequences of a probably unrecognised complication, justify routine, postoperative CT control, even though the radiation exposure is about 10 mGy higher than the conventional radiological diagnosis. The use of CT diagnosis as a routine postoperative measure is an appropriate control procedure that allows an objective assessment of the quality of the result for the patient as well as for the surgeon.

Recent development on computer aided tissue engineering--a review

The utilization of computer-aided technologies in tissue engineering has evolved in the development of a new field of computer-aided tissue engineering (CATE). This article reviews recent development and application of enabling computer technology, imaging technology, computer-aided design and computer-aided manufacturing (CAD and CAM), and rapid prototyping (RP) technology in tissue engineering, particularly, in computer-aided tissue anatomical modeling, three-dimensional (3-D) anatomy visualization and 3-D reconstruction, CAD-based anatomical modeling, computer-aided tissue classification, computer-aided tissue implantation and prototype modeling assisted surgical planning and reconstruction.

Increasing spiral CT benefits with postprocessing applications

This paper reviews the current and future role of various postprocessing tools for epidemiologically important diseases. It introduces a generic business system for diagnosis and treatment using Spiral CT. Postprocessing of Spiral CT data should become a routine part of radiological practice. As viewing moves from film to monitor displays, interactive postprocessing tools support evaluation of CT studies and will in some cases also improve diagnostic accuracy. Track-ball controlled browsing through the volume data may be performed on axial images or on multiplanar reformats (MPR). These tools can be expected to become an integral part of most CT evaluations in the near future. Already now, MPR are important adjuncts for most orthopaedic applications. Presently, three-dimensional (3D) displays are used mainly in orthopaedic and trauma patients. In CT angiography, 3D surface displays and maximum intensity projections are routine display modalities. New volume rendering techniques (VRT) with interactive parameter changes will make 3D imaging of soft tissues feasible as well. The key input factor for many postprocessing applications will be Spiral CT data sets with high z-axis resolution (subsecond scanning, thin collimation, overlapping image reconstruction) and optimised application of contrast media. The most important benefit of postprocessing is the communication with the referring physician since 3D representations are becoming increasingly important for treatment planning and control. Postprocessing services will become a key ingredient of a successful radiological practice. If radiology does not provide it, the other physicians will do it themselves. For treatment simulation, virtual surgical instruments and tissue motion models are still in their infancy and will keep software architects and physicians busy for the next decade of Spiral-CT.

Current concepts in imaging of the pelvis and hip

Over the past decade, imaging evaluation of orthopedic conditions of the pelvis and hips has become increasingly complex. Although the conventional radiograph remains the initial examination of choice, the decision between secondary tests, such as computed tomography, MR imaging, or scintigraphy is far from clear. A thorough understanding of current imaging technology is necessary for the clinician to choose the most appropriate examination for a given situation. This article reviews the current status of orthopedic imaging in the areas of acute trauma, stress injuries, osteonecrosis, arthropathies, tumors, and interventional imaging.

User metaphors for health care professional workstations

The problem encountered by health care professionals and software developers has been a lack of demonstrable visions (prototypes) for Computer-based Patient Record (CPR) and Clinical Information System (CIS) applications. This deficiency has resulted in a quest for and consideration of models, metaphors, and mind maps for the Healthcare Professional Workstation (HPW)--the access mechanism for the CPR and the CIS. The familiar physician desktop and traditional paper-based metaphors are not adequate for all aspects of clinical information processes. In the clinical care environment, the flowsheet is a transporting metaphor because many different applications and tasks can be 'transported' into the flowsheet. 3D Rooms, Gopher and Genes are familiar and transporting metaphors to be exploited for HPWs. Using transporting metaphors for HPW software emphasizes commonality and de-emphasizes diversity. Each model and metaphor has an associated mind map. Only the mental model, mental metaphor or mind map for HPW software is important. Metaphors communicate real-world analogies, and communication is at the core of what defines usability. A mind map facilitates communication by building a model in the user's mind. The barriers to HPWs are not technical; they are related to economics, ownership of patient information, liability and information standards.

3D display: a survey from theory to applications

We survey some of the literature on three-dimensional medical imaging. We report both on technical developments and on medical applications, with a concentration on material that has been published within the years 1990-1992.