Eric A. Brandser

Reliability of Standard Foot Radiographic Measurements

Fifty standing dorsoplantar and lateral foot radiographs were obtained on a consecutive series of patients seen in an orthopaedic foot and ankle clinic. These radiographs were duplicated, and eight common foot measurements were made on each pair by six experienced examiners. Measurements were made in two ways: first by a subjective visual assessment, and second by quantitative evaluation made according to strictly defined criteria. All measurements were made under controlled, ideal conditions with similar high quality goniometers. The results demonstrated overall greater reliability in the quantitative methods than the non-quantitative methods. For each of the quantitative techniques, a cumulated frequency distribution of differences between examiners was calculated. The approximate 95% bounds for these measures were: hallux-metatarsophalangeal angle = 6°, first intermetatarsal angle = 4°, metatarsophalangeal-5 angle = 11°, fourth intermetatarsal angle = 4°, AP talocalcaneal angle = 20°, lateral talocalcaneal angle = 12°, sesamoid station = 2 grades, and forefoot width = 5 mm. Physicians using these parameters to make decisions regarding patient care and clinical outcomes need to keep in mind these potential errors in making foot radiographic measurements.

Assessment of the AO/ASIF fracture classification for the distal tibia.

OBJECTIVES The purpose of this study was to assess the interobserver reliability and intraobserver reproducibility of the AO/ASIF and Rüedi and Allgöwer classifications for fractures of the distal tibia, and to determine the benefit of a computed tomography (CT) scan and experience on observer agreement for several fracture characteristics, including classification. METHODS The radiographs of forty-three fractures of the distal tibia, fourteen of which had CT scans, were assessed by groups of experienced and less-experienced observers. Each case was classified according to the AO/ASIF and Rüedi and Allgöwer systems. Several other fracture characteristics also were assessed. The kappa coefficient of agreement was calculated and used to compare the interobserver reliability and intraobserver reproducibility of the classification systems and to determine the benefit of experience and CT scans. The intraclass correlation coefficient was used to assess noncategoric data. RESULTS Interobserver and intraobserver agreements were good when classifying fractures into AO/ASIF types and significantly better than that for the Rüedi and Allgöwer system. However, agreement was poor when classifying the fractures into AO/ASIF groups. For most assessments, the experienced group tended to have higher levels of interobserver agreement, but not intraobserver agreement. Viewing the CT scans improved agreement on the percentage of articular surface involved, but it did not improve interobserver reliability or intraobserver reproducibility for either of the classification systems. CONCLUSION The AO/ASIF classification for fractures of the distal tibia has good observer agreement at the type level, but poor agreement at the group level. Experience tends to improve interobserver agreement, but not intraobserver agreement. Viewing CT scans does not improve agreement on classification, but it tends to improve agreement on articular surface involvement.

Imaging of muscle injuries

Abstract Although skeletal muscle is the single largest tissue in the body, there is little written about it in the radiologic literature. Indirect muscle injuries, also called strains or tears, are common in athletics, and knowing the morphology and physiology of the muscle-tendon unit is the key to the understanding of these injuries. Eccentric muscle activation produces more tension within the muscle than when it is activated concentrically, making it more susceptible to tearing. Injuries involving the muscle belly tend to occur near the myotendinous junction. In adolescents, the weakest link in the muscle-tendon-bone complex is the apophysis. Traditionally, plain radiography has been the main diagnostic modality for evaluation of these injuries; however, with the advent of MRI it has become much easier to diagnose injuries primarily affecting the soft tissues. This article reviews the anatomy and physiology of the muscle-tendon unit as they relate to indirect muscle injuries. Examples of common muscle injuries are illustrated.

Gaze Dwell Times on Acute Trauma Injuries Missed Because of Satisfaction of Search

RATIONALE AND OBJECTIVES The authors performed this study to determine whether satisfaction of search (SOS) errors in patients with multiple traumas are caused by faulty visual scanning, faulty recognition, or faulty decision making. MATERIALS AND METHODS A series of radiographs were obtained in patients with multiple traumas. Radiologists interpreted each series under two experimental conditions: when the first radiograph in the series included a fracture, and when it did not. In the first experiment, the initial radiographs showed nondisplaced fractures of the extremities (minor fractures); in the second experiment, the initial radiographs showed abnormalities of greater clinical importance (major fractures). Each series also included a radiograph with a subtle (test) fracture and a normal radiograph on which detection accuracy was measured. In each experiment, gaze dwell time was recorded as 10 radiologists reviewed images from 10 simulated cases of multiple trauma. RESULTS An SOS effect could be demonstrated only in the second experiment. Analysis of dwell times showed that search on subsequent radiographs was shortened when the initial radiograph contained a fracture; however, the errors were not based on faulty scanning. CONCLUSION The SOS effect in musculoskeletal trauma is not caused by faulty scanning. Demonstration of an SOS effect on test fractures with major but not minor additional fractures suggests that detection of other fractures is inversely related to the severity of the detected fracture.

A contaminated binormal model for ROC data

Rationale and Objectives. Receiver operating characteristic (ROC) data with false-positive fractions of 0 are often difficult to fit with standard ROC methods and are sometimes discarded. Some extreme examples of such data were analyzed to evaluate the nature of these difficulties. Materials and Methods. Rating reports of fracture for single-view ankle radiographs were analyzed with the binormal ROC model and with two ROC models that keep the ROC curve from crossing the chance line. Because fractures were almost never reported that were not present, some views and locations yielded only ROC points with false-positive fractions of 0, while others yielded at least one ROC point with a non-0 false-positive fraction. Results. The models tended to yield ROC areas close to or equal to 1. ROC areas of 1 imply a true-positive fraction close to 1; yet the data contained no such fractions. When all false-positive fractions were 0, the true-positive fraction could be much higher for one view than another for all observers. ROC areas gave little or no hint of these unmistakable differences in performance. Conclusion. These data challenge the validity and robustness of current ROC models. A key aspect of ankle fractures is that some may be visible on one view but not at all visible on another.

Coronal Plane Rotation of the First Metatarsal

A method for measuring first metatarsal rotation on weightbearing tangential radiographs is described. Under controlled conditions using cadaver specimens, 5° changes in first metatarsal rotation were associated with a mean change in radiographically measured rotation of 5.4° (SD = 1.7°). A clinical study of 30 hallux valgus and 30 control patients was undertaken to assess the reliability of the method of measurement. The overall reliability was high for both hallux valgus and control patients (r = 0.93 and 0.95, respectively). In these two groups, no significant difference was found between the mean values for first metatarsal rotation. Likewise, we found no correlation between first metatarsal rotation measured on tangential standing (“sesamoid” view) radiographs and the first metatarsophalangeal angle or the intermetatarsal 1–2 angle measured on anteroposterior standing radiographs.

Longitudinal tibial stress fractures: a report of eight cases and review of the literature.

PURPOSE We present the imaging features of longitudinal stress fractures in eight patients and evaluate the literature to determine which tests are most useful for making this diagnosis. METHOD Three musculoskeletal radiologists retrospectively reviewed eight cases of longitudinal tibial stress fractures presenting between 1988 and 1994. Reports on 36 cases, cited in the literature between 1960 and 1996, also were reviewed. Imaging modalities used and characteristic imaging features were noted. RESULTS Plain radiographs had a characteristic appearance in approximately 28% of patients. Initially, plain films were negative, and in most cases, they eventually showed characteristic radiographic features. However, 25% of cases failed to demonstrate a plain film abnormality, with the diagnosis made by other modalities. CT or MRI is often diagnostic, and longitudinal stress fractures have characteristic imaging features with each modality. While sensitive, bone scan has lower specificity than either CT or MRI. CONCLUSION Longitudinal stress fractures have characteristic imaging features, and familiarity with these features is necessary for timely and efficient diagnosis, avoiding morbidity due to delay or use of unnecessary tests.

Radiographic Abnormalities of the Lumbar Spine in College Football Players A Comparative Analysis

The purpose of this study was to make a direct comparison between lumbar spine radiographs of incoming college football players and of an age-matched control group to determine whether there is a higher prevalence of lumbar spine abnormalities in football players before competing at the Division I level. We reviewed 187 lumbar spine radiographs. Of these, 104 were taken as a standard part of the preparticipation physical examination for incoming college football players. The remaining 83 radiographs were taken during routine preemployment physicals at a local factory. Each radiograph was read independently by three separate orthopaedic radiologists in a blinded fashion. Data were collected and statistically evaluated for 13 variables. The rate of spondylolysis was only 4.8% in our group of athletes and 6.0% in the control group (not significantly different). Only in the category of degenerative changes was a significant difference found. The control group had a 16.9% incidence of disk space narrowing and spurring and the football players had a 6.7% incidence. The remainder of the variables were not significantly different between the two groups. Our findings differ from previously published reports and indicate that football players entering college at the Division I level may have a similar prevalence of radiographic lumbar spine abnormalities, including spondylolysis and spondylolisthesis, as age-matched controls.

Acetabular fractures: A systematic approach to classification

The classification of acetabular fractures is important for preoperative planning; interpretation of imaging studies, however, is often difficult. Plain radiography is the primary method for evaluation of these injuries, and computed tomography is now commonplace for the preoperative classification of patients with acetabular fractures. We have developed a systematic approach that aids in the classification of these fractures.

Missed fractures on emergency room ankle radiographs: An analysis of 433 patients

The purpose of this study was to review fractures and radiographic abnormalities that are detectable, but often overlooked, on a standard ankle radiographic series. We carried out a retrospective review of 556 consecutive ankle radiographic series obtained between June 1, 1995, and May 31, 1996. From this population, 433 complete ankle radiographic series on patients with suspected trauma were selected. The original radiologists interpretation was compared to a twostep “gold standard” interpretation, consisting of reinterpretation by a musculoskeletal radiologist with the patients medical and imaging records at hand, with review of discrepant cases by a consensus panel.Eighteen studies were incorrectly interpreted at the initial reading, yielding an overall error rate of 4.2%. Fifteen of the errors were missed fractures, ankle syndesmotic widening, or incorrect classification of old fractures as acute. The rate for this type of error was 3.5%. The most commonly missed fractures were of the talus (4 patients), followed by fracture of the base of the fifth metatarsal and calcaneal stress fracture (2 cases each); tibiofibular syndesmotic injury was missed in 2 cases.Missed fractures on ankle radiographs most commonly involved bones of the hindfoot, especially the talus. It is important to recognize these uncommon and easily missed fractures, so that a modified search pattern may result in improved accuracy of radiographic interpretation.