Quantitative 3-dimensional computed tomography measurements of coronoid fractures

Considerable variation in current coronoid height and fracture measurement techniques: a systematic review

BACKGROUND

Coronoid fractures usually occur in the presence of a significant osseoligamentous injury to the elbow. Fracture size and location correlate with degree of instability and many authors have attempted to analyze the effect of fracture variation on decision making and outcome. There remains no standardized technique for measuring coronoid height or fracture size. The aim of this study was to appraise the literature regarding techniques for coronoid height measurement in order to understand variation.

METHODS

Preferred Reporting Items of Systematic Reviews and Meta-Analyses guidelines were followed. A search was performed to identify studies with either a description of coronoid height, fracture size, or bone loss using the terms (Coronoid) AND (Measurement) OR (Size) OR (Height). Articles were shortlisted by screening for topic relevance based on title, abstract and, if required, full-text review. Exclusion criteria were non-English articles, those on nonhuman species or parts other than the ulna coronoid process, and studies that included patients with pre-existing elbow pathology. Shortlisted articles were grouped based on study type, imaging modality, measurement technique, and measurement parameter as well as its location along the coronoid.

RESULTS

Thirty out of the initially identified 494 articles met the inclusion criteria. Twenty-one articles were clinical studies, 8 were cadaveric studies, and 1 combined patients as well as cadavers. A variety of imaging modalities (plain radiographs, 2-dimensional computed tomography [CT], 3-dimensional CT, magnetic resonance imaging or a combination of these) were used with CT scan (either 2-dimensional images or 3-dimensional reconstructions or both) being the most common modality used by 21 studies. Measurement technique also varied from uniplanar linear measurements in 15 studies to multiplanar area and volumetric measurements in 6 studies to techniques describing various angles and indices as an indirect measure of coronoid height in 8 studies. Across the 30 shortlisted studies, 19 different measurement techniques were identified. Fifteen studies measured normal coronoid height while the other 15 measured intact coronoid and/or fracture fragment height. The location of this measurement was also variable between studies with measurements at the apex of the coronoid in 24/30 (80%) of studies. Measurement accuracy was assessed by only 1 study. A total of 12/30 (40%) studies reported on the interobserver and intraobserver reliability of their measurement technique.

CONCLUSION

The systemic review demonstrated considerable variability between studies that report coronoid height or fracture size measurements. This variability makes comparison of coronoid height or fracture measurements and recommendations based on these between studies unreliable. There is need for development of a consistent, easy to use, and reproducible technique for coronoid height and bone loss.

The value of digital 3D models in evaluating surgical outcomes using the uninjured contralateral acetabulum after acetabular fracture repair

BACKGROUND

Currently, assessment of acetabular fracture reduction is mainly performed by evaluating 2D slices of 3D CT scans. This subjective method can potentially be improved by using 3D models and objective analysis tools. In order to evaluate the potential value of digital 3D reconstructed models in the assessment of acetabular fracture reduction, 3D reconstructions of the fractured acetabulum were compared to the mirrored healthy contralateral side for both the pre-, and post-surgical setting.

METHODS

Thirteen patients with one-sided acetabular fractures were included in the study. All patients received a pre-, and postoperative CT scan. The similarity between the healthy acetabulum and the contralateral fractured acetabulum was determined by two observers for both the pre-, and postoperative setting by completing the following four steps; (1) mirroring of the fractured acetabulum, (2) initial manual alignment of this mirrored 3D model to the contralateral version, (3) surface-based matching (iterative closest point registration) using the acetabular cartilage surface, and (4) calculating the surface distances between affected and healthy acetabular 3D models. Descriptive statistics showed the surface distance between pre-, and post-surgical reduction, as well as the interobserver variability.

RESULTS

A total of 13 patients with an acetabular fracture were included; 11 males and 2 females with a mean ± SD age of 55.6 ± 14.7 years. Digital mirroring of the fractured acetabula to the healthy acetabula was successful for both preoperative and postoperative situations in all patients. The median distance between both fractured and mirrored healthy contralateral acetabula was significantly larger (p<0.01) for the preoperative group (2.21 mm (interquartile range (IQR): 1.30 mm)) compared to the postoperative group (0.93 mm (IQR: 0.59 mm)). The median distance deviation was not significantly different (p = 0.96) between observers.

CONCLUSIONS

The results of comparing 3D model of fractured acetabula with the contra-lateral healthy acetabula before, and after surgical repair indicate that this method can be a suitable tool to objectively assess acetabular fracture reduction. Further research is needed to confirm the usefulness to predict future arthrosis after surgical repair.

A new quantitative 3D gap area measurement of fracture displacement of intra-articular distal radius fractures: Reliability and clinical applicability

INTRODUCTION

Gap and step-off measurements are generally used in the surgical decision-making process of distal radius fractures. Unfortunately, there is no consensus on treatment choice as these measurements are prone to inter- and intraobserver variability. In this study, we aim to introduce a new 3D fracture quantification method and compare it to conventional fracture analysis.

METHODS

Forty patients with a minimally displaced intra-articular distal radius fracture that was treated nonoperatively between 2008-2015 were included. 2D-CT images were reassessed by three orthopedic trauma surgeons who performed gap and step-off measurements. Subsequently, 3D models were created and a 3D measurement method for fracture displacement was developed. For each fracture, the '3D gap area' (3D surface between all fracture fragments) was determined by three observers. Interobserver agreements were calculated for all measurements, and the intraobserver agreement was calculated for the new 3D measurement. All patients completed two questionnaires in order to link our measurements to functional outcome.

RESULTS

The interobserver agreement of the 2D measurements was fair (ICC = 0.54) for the gap and poor (ICC = 0.21) for the step-off. The median gap was 2.8 (IQR: 1.9-3.5) mm and step-off was 0.9 (IQR: 0.0-1.6) mm. Interobserver agreement on 3D gap area measurements was excellent (ICC = 0.81), with a median difference between measurements of 6.0 (IQR: 2.0-19.0) mm2, which indicates reliable assessment of 3D fracture displacement. Intraobserver agreement was also excellent (ICC = 0.98), with a median difference of 4.0 (IQR: 1.5-5.5) mm2. No significant differences in clinical outcome were found between the above and below 2mm displacement groups. The score of the DASH was 3.4 (IQR: 0.4-8.8) versus 4.2 (IQR: 0.0-11.6) respectively. Results from the PRWE questionnaire shows a similar result of 3.5 (IQR: 0.0-12.6) versus 5.0 (IQR: 0.0-25.5).

CONCLUSION

3D gap area is a more objective measurement method compared to the conventional gap and step-off measurements to quantify the level of fracture displacement of distal radius fractures. 3D fracture assessment can be used in addition to the currently used classification systems of distal radius fractures.

Quantitative Three-Dimensional Measurements of Acetabular Fracture Displacement Could Be Predictive for Native Hip Survivorship

This study aims to develop a three-dimensional (3D) measurement for acetabular fracture displacement, determine the inter- and intra-observer variability, and correlate the measurement with clinical outcome. Three-dimensional models were created for 100 patients surgically treated for acetabular fractures. The ‘3D gap area’, the 3D surface between all the fracture fragments, was developed. The association between the 3D gap area and the risk of conversion to a total hip arthroplasty (THA) was determined by an ROC curve and a Cox regression analysis. The 3D gap area had an excellent inter-observer and intra-observer reliability. The preoperative median 3D gap area for patients without and with a THA was 1731 mm2 versus 2237 mm2. The median postoperative 3D gap area was 640 mm2 versus 845 mm2. The area under the curve was 0.63. The Cox regression analysis showed that a preoperative 3D gap area > 2103 mm2 and a postoperative 3D gap area > 1058 mm2 were independently associated with a 3.0 versus 2.4 times higher risk of conversion to a THA. A 3D assessment of acetabular fractures is feasible, reproducible, and correlates with clinical outcome. Three-dimensional measurements could be added to the current classification systems to quantify the level of fracture displacement and to assess operative results.

Quantitative Three-Dimensional Computed Tomography Measurements Provide a Precise Diagnosis of Fractures of the Mandibular Condylar Process

As 2D quantitative measurements are often insufficient, a standardized 3D quantitative measurement method was developed to analyze mandibular condylar fractures, and correlate the results with the mandibular condylar fracture classifications of Loukota and Spiessl and Schroll and clinical parameters. Thirty-two patients with a unilateral mandibular condylar fracture were evaluated using OPT, 2D (CB)CT images, and 3D imaging to measure the extent of the fractures. The maximum mouth opening (MMO) was measured. Ramus height loss could be measured only in OPT, but not in 2D CT images. The Intraclass Correlation Coefficient was excellent in the 3D measurements. In the Loukota classification, condylar neck fractures had the largest median 3D displacement and the highest rotations of the fracture fragments. The largest fracture volume was observed in base fractures. According to the Spiessl and Schroll classification, type V fractures had the largest median 3D displacement and the highest rotation in the X-axis and Z-axis. Type I fractures had the largest fracture volume. We found a moderate negative correlation between MMO and 3D displacement and rotation on Z-axis. The 2D quantitative analysis of condylar fractures is limited, imprecise, and not reproducible, while quantitative 3D measurements provide extensive, precise, objective, and reproducible information.

Fracture patterns in midshaft clavicle fractures

Current classifications of midshaft clavicle fractures are based on radiography. The aim of the study was to evaluate the fracture pattern of clavicle fractures using 3-dimensional computed tomography (3D CT). A retrospective analysis was performed on CT scans of 65 acute clavicle fractures. Using quantitative 3D CT reconstruction techniques, the fracture of the clavicle was virtually reduced. Based on these reconstructions, a group-based fracture heat map and small fragment heat map, and the location of the most common fracture line were determined. Also, the direction and amount of displacement were evaluated. Three fracture patterns could be distinguished. The primary fracture line in type 1 is going from posteromedial to anterolateral and located between 50% and 68% of the clavicle’s length. In type 2, a transverse fracture line is located around 55%, and in type 3, a superolateral to inferomedial line is located between 47% and 56%. Wedged fracture fragments can be seen in types 1 and 2 and are mainly situated inferiorly. The displacement is similar in all types, but the main direction of displacement is specific for the different types (posterior, anterior, inferior). We can conclude that several fracture patterns can be seen in clavicle fractures. Most fractures are located laterally at the midshaft of the clavicle. Wedged segments are mainly located inferiorly, and at the posterior part of the clavicle, no comminution is ever seen. The direction of displacement depends on the fracture pattern.

Analysis of Fracture Characteristic and Medial Collateral Ligament Injury Relationships in Terrible Triad Elbow Injuries

PURPOSE

The objectives of this study were to identify the relationship between fracture characteristics and medial collateral ligament (MCL) injuries in terrible triad injuries of the elbow.

METHODS

Between 2010 and 2018, 60 patients who underwent surgery for terrible triad elbow injuries were retrospectively reviewed. Using magnetic resonance imaging (MRI) assessments, patients were stratified into those who had intact or low-grade partial MCL tears (low-grade MRI-MCL group) and those who had high-grade partial or full-thickness MCL tears (high-grade MRI-MCL group). We also analyzed patients according to whether they underwent MCL repair surgery. Fractures of the radial head were assessed according to Mason's classification system and measurements of fracture fragment arc on axial cuts. Fractures of the coronoid processes were assessed according to the system of Regan and Morrey and measurements of coronoid process volumes.

RESULTS

Patients in the high-grade MRI-MCL group (28 patients) had a more comminuted and higher fragment arc of radial head fractures than those in the low-grade MRI-MCL group (32 patients) (143º ± 45º vs 119º ± 31º). However, the volume of coronoid fracture fragments was smaller in the high-grade MRI-MCL than in the low-grade MRI-MCL group (359 ± 325 mm³ vs 722 ± 448 mm³). The MCL repair group (22 patients) also had a more comminuted and higher fragment arc in radial head fractures (153º ± 44º vs 117º ± 31º) and a smaller coronoid process fracture volume (236 ± 224 mm³ vs 735 ± 419 mm³) than the non-MCL repair group (38 patients).

CONCLUSIONS

Our results demonstrated that high-grade MCL injuries are associated with comminuted and larger-sized radial head fractures, as well as smaller-sized coronoid process fractures in terrible triad injuries. In making a decision regarding surgical treatment, these fracture characteristics could help to predict the severity for MCL injury in terrible triad injuries.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

Morphological characteristics of fractures of the anteromedial facet of the coronoid in posteromedial rotatory instability of the elbow: a three-dimensional CT remodeling study

BACKGROUND

Fractures of the anteromedial facet of the coronoid in posteromedial rotatory instability of the elbow are classified into 3 subtypes based on their location. The purpose of this study was to analyze the fracture morphology of anteromedial facet fractures in their 3 subtypes (anteromedial rim, anteromedial rim + tip, and anteromedial rim + sublime tubercle [±tip]).

METHODS

Three-dimensional computed tomography remodeling was used to evaluate anteromedial facet fractures in a consecutive series of 40 patients, all of whom were affected by posteromedial rotatory instability of the elbow. Characteristics of the fractures, including the number of fragments, size of fragments, plane of the fracture line, and involvement of the sublime tubercle and radial notch, were measured for each subtype of the anteromedial facet fractures.

RESULTS

Each subtype had a typical fracture pattern and distinct size. The fracture subtype 1 showed a single-fragment fracture, subtype 2 showed either a single- or dual-fragment fracture, and subtype 3 showed either a dual- or triple-fragment fracture. The angle between the fracture line and the coronal plane was greatest in subtype 3 fractures. The surface area of the fragment was largest in subtype 3 fractures. The percentages of articular involvement of the sublime tubercle were 0% in subtype 1, 47% in subtype 2, and 79% in subtype 3. The percentages of articular involvement of the radial notch were 0% in subtype 1, 7% in subtype 2, and 8% in subtype 3.

CONCLUSION

Analysis with quantitative 3-dimensional computed tomography showed the characteristic morphology of each subtype of anteromedial facet fracture. Subtype 1 comprised 1 fragment with the smallest fragment size. Subtype 2 was a single- or dual-fragment fracture, the size of which should be considered in the treatment plan. Subtype 3 was a large fragment comprising the sublime tubercle. Our findings are significant because they highlight unique fracture morphology that may help surgeons to distinguish one fracture subtype from another in clinical practice.

Classification of tibial plateau fractures using 3DCT with and without subtraction of unfractured bones

BACKGROUND

The addition of 3D CT scans for observers evaluating tibial plateau fractures decreases agreement and diagnostic accuracy, possibly due to obstruction of the view by unfractured bones (i.e., patella, fibula, and femur) in 3D reconstructions.

QUESTIONS/PURPOSES

This study compared (1) the interobserver agreement between (subgroups of) observers classifying 3DCT reconstructions of tibial plateau fractures according to Schatzker, Luo, and AO/OTA, (2) recognition of different fracture characteristics, and (3) the level of confidence on a scale from 0 to 10 with and without subtraction of the unfractured bones.

METHODS

We selected twenty consecutive 3DCT reconstructions of tibial plateau fractures treated in a level I trauma center between 2013 and 2014. Members of the Science of Variation Group were randomized (1:1) to evaluate reconstructions with or without subtraction of the unfractured bone. Forty-nine surgeons completed the survey. The interobserver agreement was determined using Fleiss' kappa, and bootstrapping (resamples = 1000) was used to calculate the standard error, z statistic, and confidence intervals.

RESULTS

Overall, subtraction of unfractured bones did not affect interobserver agreement in Schatzker, Luo, and AO/OTA classification systems, agreement on the presence of fracture characteristics, and level of confidence. In subgroup analysis, non-trauma surgeons had significantly higher agreement in the three classification systems with subtraction. For fracture characteristics, some subgroups had higher agreement while others had lower agreement with subtraction.

DISCUSSION

The finding that agreement on classification of tibial plateau fractures is limited on 3DCT scan and is not improved by subtraction of unfractured bones suggests that disagreement may be based on variations in understanding and bias. Reliability of these classification systems might benefit from a focus on accounting for these pre-existing conceptualizations rather than further emphasis on imaging detail.

LEVEL OF EVIDENCE

Diagnostic, level 1.

Quantitative 3D measurements of tibial plateau fractures

Fracture gap and step-off measurements on 2DCT-slices probably underestimate the complex multi-directional features of tibial plateau fractures. Our aim was to develop a quantitative 3D-CT (Q3DCT) fracture analysis of these injuries. CT-based 3D models were created for 10 patients with a tibial plateau fracture. Several 3D measures (gap area, articular surface involvement, 3D displacement) were developed and tested. Gaps and step-offs were measured in 2D and 3D. All measurements were repeated by six observers and the reproducibility was determined by intra-class correlation coefficients. Q3DCT measurements demonstrated a median gap of 5.3 mm, step-off of 5.2 mm, gap area of 235 mm², articular surface involvement of 33% and 3D displacement of 6.1 mm. The inter-rater reliability was higher in the Q3DCT than in the 2DCT measurements for both the gap (0.96 vs. 0.81) and step-off (0.63 vs. 0.32). Q3DCT measurements showed excellent reliability (ICC of 0.94 for gap area, 1 for articular surface involvement and 0.99 for 3D displacement). Q3DCT fracture analysis of tibial plateau fractures is feasible and shows excellent reliability. 3D measurements could be used together with the current classification systems to quantify the true extent of these complex multi-directional fractures in a standardized way.

Clinical and radiological evaluation of surgical management in olecranon fracture-dislocations

PURPOSE

The treatment of olecranon fracture-dislocations (OFDs) remains challenging. OFDs are often misdiagnosed as Monteggia lesions, and the real frequency is actually higher. However, studies on OFDs are limited. This study aimed to report on the surgical management of OFDs and to highlight the importance of three-dimensional computed tomography (3D CT) evaluation in the treatment of OFDs.

MATERIALS AND METHODS

The study participants included 18 patients (11 men, 7 women, mean age 44 years (range 24-78) with OFDs. Each patient's medical records, radiographs, and 3D CT scans were reviewed for demographics, injury details, operative findings, and information about radiological and functional outcomes. The patients were divided into 2 groups according to the direction of the dislocation: the posterior dislocation group (group 1, 7 patients) and anterior dislocation group (group 2, 11 patients). The clinical evaluation was performed according to Broberg-Morrey and the American Shoulder and Elbow Surgeons-Elbow (ASES-E) scoring systems.

RESULTS

The mean follow-up period was 39 months (range 25-62 months). The Broberg-Morrey results were excellent in 4, good in 9, fair in 3, and poor in 2 patients. The mean ASES-E score was 84.83 (range 48-100) points. There were signs of ulna-humeral arthrosis in 5 elbows. Arthrosis was graded as grade 1, grade 2, and grade 3 in 3, 1, and 1 elbows, respectively. Partial sensory recovery was observed in one patient with postoperative ulnar neuropathy at the last follow-up visit.

CONCLUSIONS

OFDs are complex injuries of the proximal ulna and may involve the radial head, coronoid process, and lateral collateral ligament. The effective treatment of OFDs begins with the proper identification of the injury with 3D CT. A secure fixation including the coronoid process is mandatory for the elbow joint stability. Insufficient restoration of the trochlear notch may lead to problems with loss of motion and arthrosis. Although an application of a pre-contoured locking anatomical olecranon plate can simplify the fixation procedure in most cases, the surgeons' equipment should also include radial head implant, coronoid plates, headless screws, small cannulated screw system, suture anchors, fluoroscopy, and articulated external fixator.

Introduction of a three-dimensional computed tomography measurement method for acetabular fractures

Introduction

Acetabular fractures consist of complex fracture patterns whereby bone fragments are displaced in different directions. Two-dimensional computed tomography (2DCT) gap and step-off measurements tend to underestimate the multidirectional features of these fractures. The aim was to develop a three-dimensional computed tomography (3DCT) measurement method for acetabular fractures and validate whether this method will provide an observer independent fracture characterization.

Materials and methods

Sixty patients, operated for an acetabular fracture between 2007 and 2018, were included. The displacement was measured on the pre- and postoperative CT scans. Pre- and postoperative CT-based 3D models were made for each patient. Multiple 3D measurements, namely the 3D step-off, gap and the total gap area were introduced to quantify the preoperative and postoperative displacement. The Wilcoxon signed rank analysis was used to compare the 2DCT and 3DCT measurements.

Results

The preoperative displacement was significantly underestimated by 2DCT measurements in comparison with 3DCT measurements (2D vs. 3D; step-off 8 vs. 16 mm with P < 0.001; gap 19 vs. 21 mm with P = 0.001). The same applies to the postoperative residual displacement (2D vs. 3D; step-off 0 vs. 6 mm; gap 3 vs. 8 mm; P < 0.001). The total gap area, defined as the surface area between all fracture lines in the 3D model, was measured for each patient, resulting in a median value of 722 mm² preoperatively and 168 mm² postoperatively, with excellent inter- and intra-rater reliability.

Conclusion

2DCT measurements tend to underestimate the initial and residual displacement in complex acetabular fractures. A 3DCT analysis of these injuries was developed to overcome this and should be used in addition to the Judet/Letournel and AO/OTA classification systems, in order to provide an observer independent quantifiable fracture description and accurate assessment of the fracture reduction.

Articular coronal fracture angle of posteromedial tibial plateau fragments: A computed tomography fracture mapping study

OBJECTIVES

The purpose of this study is to analyze posteromedial fragment morphology using two-dimensional computed tomography fracture mapping and to compare posteromedial fragment morphology in various Schatzker type tibial plateau fractures.

MATERIALS & METHODS

One hundred twenty-seven consecutive AO/OTA B- and C-type tibial plateau fractures were retrospectively analyzed using 2DCT fracture mapping. The posteromedial articular fracture angle and articular surface areas of all fractures with posteromedial fragments were calculated. Based on biomechanical studies, posteromedial fragments with coronal fracture angles >68° were considered amenable for anterolateral stabilization with standardized plating. Kruskall-Wallis non-parametric test was used for statistical comparison of morphological features of posteromedial fragments between the various Schatzker types.

RESULTS

Forty-seven out of 127 tibial plateau fractures included a posteromedial fragment. The mean posteromedial articular fracture angle was 44° (range: 2°-90^o, standard deviation: 23°). Forty fragments (85%) had a fracture angle of <68°, increasing the risk for insufficient stabilization with standardized anterolateral plating. The mean articular surface area was 34% of the entire tibial plateau (range: 7%-53%, SD: 12%). There were no significant differences in posteromedial fragment morphology between Schatzker type IV, V, and VI fractures.

DISCUSSION AND CONCLUSION

Posteromedial fragments commonly occur not only in Schatzker type V and VI, but also in Schatzker type IV tibial plateau fractures. Eighty-five percent of tibial plateau fractures with a posteromedial fragment may benefit from non-standard customized lateral plating, or may require an additional medial or posterior surgical approach for fracture-specific fixation to optimize screw purchase and biomechanical stability.

Quantitative measurements of facets on the ulnar coronoid process from reformatted CT images

Background

To quantify the size and angle of the medial and lateral facets of the ulnar coronoid process by reformatted computed tomography (CT) imaging.

Methods

Elbow CT images were retrospectively selected from the picture archiving and communication system in our hospital over a 5-year period (January 2011 to December 2015). The widths, heights, gradient and tilt angles of both the medial and lateral facet of the ulnar coronoid process were measured using two-dimensional (2D) reformations of CT images.

Results

Our database research yielded 120 elbow joints (53 right, 67 left) of 120 patients (54 males, 66 females) which fulfilled our criteria. The average width of the two facets of the ulnar coronoid process were 13.34±1.85 mm for the medial facet and 8.39±1.29 mm for the lateral facet. The average height of the medial facet was 18.45±3.38 mm and the lateral facet was 17.55±3.81 mm. The average tilt angles of medial and lateral facet were 80.34°±7.71° and 98.78°±5.71° respectively. The average gradient angles of the medial and lateral facet ridge were 60.02°±8.78° and 36.97°±4.99° respectively. The length of the lateral facet ridge was longer than the medial facet ridge.

Conclusions

Reformatted CT images allow for multiple, accurate measurements of facets on the ulnar coronoid process. These measurements can be applied to guiding appropriate surgical interventions for fractures in this area.

Topographic Analysis of 2 Alternative Donor Sites of the Ipsilateral Elbow in the Treatment of Capitellar Osteochondritis Dissecans

PURPOSE

To find the best topographic subchondral bone match between the capitellum and 2 proposed alternative donor sites of the ipsilateral elbow for capitellar osteochondral autologous transplantation: the non-articulating part of the radial head and the lateral olecranon tip.

METHODS

In our retrospective database, 20 patients with an unremarkable computed tomography scan of the elbow despite clinical suspicion were identified for analysis. Included were patients aged 11 to 20 years with intact osseous structures and a computed tomography slice thickness of 1.25 mm or less. Three-dimensional polygon models were created using a standard predefined threshold, after which 4 articular surface lesions on the capitellum were created: central 40°, central 60°, lateral 40°, and lateral 60°. In addition, 3 donor locations on the non-articulating part of the radial head (diameter, 5 mm) and the lateral olecranon tip (diameter, 3.5 mm) were created. For each of 24 donor-recipient combinations, the donor graft surface was virtually placed on the recipient surface to quantify the mean distance between surfaces.

RESULTS

The group of 20 patients consisted of 16 male and 4 female patients with a mean age of 15.9 years (range, 12-18 years). For a central 40° lesion, the mean distance across all 6 donor-recipient combinations ranged from 0.085 ± 0.023 to 0.118 ± 0.036 mm; for a central 60° lesion, the mean distance ranged from 0.075 ± 0.018 to 0.117 ± 0.062 mm; for a lateral 40° lesion, the mean distance ranged from 0.087 ± 0.030 to 0.182 ± 0.226 mm; and for a lateral 60° lesion, the mean distance ranged from 0.084 ± 0.048 to 0.115 ± 0.045 mm. There were no differences in topographic matching between donor-recipient combinations.

CONCLUSIONS

The findings of this study show a less than 0.2-mm difference in the topographic subchondral bone match between 4 common lesion locations on the capitellum and 2 alternative donor sites of the ipsilateral elbow for capitellar osteochondral autologous transplantation: the non-articulating part of the radial head and the lateral olecranon tip.

CLINICAL RELEVANCE

These findings suggest that the non-articulating part of the radial head and the lateral olecranon tip may potentially be used as a donor source when treating capitellar osteochondritis dissecans.

Comparing radial styloid size between osteoarthritic and healthy wrists: a pathoanatomical three-dimensional study

Radial styloid pointing due to spur formation is considered an early sign of osteoarthritis, but is sometimes difficult to distinguish from normal anatomic variation. In this pathoanatomical study we used three-dimensional imaging techniques to evaluate quantitatively whether the styloid size is larger in wrists with scaphoid non-union than in healthy wrists. We compared these findings with duration of the non-union and with the scaphoid non-union advanced collapse classification, which was based on radiographic assessment of the general level of wrist osteoarthritis. In 31 patients, the injured styloid was consistently larger than the contralateral healthy styloid. In 74% of the patients this pathoanatomical difference (maximum 5 mm) exceeded anatomical left-to-right variation in styloid size (maximum 2 mm), indicating significant pointing. Increased styloid pointing was associated with older non-unions, and with more severe osteoarthritis. Three-dimensional styloid pointing analysis is an objective method to assess osteoarthritic progression. Combining traditional qualitative evaluation and quantitative measurements may improve the classification of wrist osteoarthritis.

LEVEL OF EVIDENCE

IV.

Controversies in Fractures of the Proximal Ulna

The olecranon process, coronoid process, and greater sigmoid notch are important components of the complex proximal ulna. Along with providing bony stability to the ulnohumeral joint, the proximal ulna serves as the attachment site of many important muscles and ligaments that impart soft tissue stability to the elbow joint. Management of proximal ulnar fractures continues to evolve as advances in imaging and anatomic and biomechanical studies have led to improvements in available implants; however, controversies remain, as shown in the current relevant literature.

Involvement of the lesser sigmoid notch in elbow fracture dislocations

BACKGROUND

This study addressed the primary null hypothesis that there is no difference in the articular surface area of the lesser sigmoid notch involved among Mayo classes. Secondarily, we analyzed the fracture line location and the pattern of lesser sigmoid notch articular surface involvement among Mayo classes.

METHODS

Using quantitative 3-dimensional computed tomography, we reconstructed and analyzed fractures involving the lesser sigmoid notch articular surface in 52 patients. Further, we assessed the surface area involved in the fracture, the number of fracture fragments, and the location and direction of the fracture lines. Coronoid fractures were classified according to Mayo types.

RESULTS

There was no significant difference between Mayo types 1 and 2 in any characteristic of the involvement of the lesser sigmoid notch articular surface, whereas Mayo type 3 was significantly different from both Mayo types 1 and 2 in the area involved in the fracture (42% in Mayo type 3 vs. 9% in Mayo types 1 and 2), the number of articular fragments (>3 fragments in type 3 vs. 2 fragments in types 1 and 2), and the direction of fracture line (both horizontal and vertical lines in type 3 vs. only horizontal line in types 1 and 2).

CONCLUSION

Mayo type III results in a more complex fracture, which might need to be addressed directly or indirectly during open reduction with internal fixation of olecranon fracture dislocations because changes in the geometry of lesser sigmoid notch may affect the radioulnar joint if it remains incongruent.

Fracture mapping of displaced partial articular fractures of the radial head

BACKGROUND

Recognition of patterns of traumatic elbow instability helps anticipate specific fracture characteristics and associated injuries. The objective of this study was to assess the association of fracture line distribution and location of displaced partial articular radial head fractures with specific patterns of traumatic elbow instability using fracture mapping techniques.

METHODS

Fracture line distribution and location of 66 acute displaced partial articular radial head fractures were identified using quantitative 3-dimensional computed tomography reconstructions that allowed reduction of fracture fragments and a standardized method to divide the radial head into quadrants with forearm in neutral position. Based on qualitative and quantitative assessment of fracture maps, the association between fracture characteristics of displaced partial articular radial head fractures and specific elbow fracture patterns was determined.

RESULTS

In partial articular radial head fractures, the highest fracture line intensity was located in the anterolateral quadrant near the center of the radial head. Fracture location corresponded with fracture line distribution; most fractures involved the anterolateral quadrant (n = 65; 98%), whereas parts of the posteromedial quadrant were involved in a minority of the fractures (n = 10; 15%). The association of fracture line distribution and location with overall fracture patterns of the elbow, as depicted on fracture maps, was not statistically significant.

CONCLUSION

Fracture maps demonstrated no association between fracture line distribution and location of displaced partial articular fractures of the radial head and overall specific patterns of traumatic elbow instability, suggesting a common fracture mechanism that involves the anterolateral part of the radial head in most patients.

Quantitative 3-dimensional computed tomography analysis of olecranon fractures

HYPOTHESIS/BACKGROUND

Olecranon fractures have variable size of the proximal fragment, patterns of fragmentation, and subluxation of the ulnohumeral joint that might be better understood and categorized on the basis of quantitative 3-dimensional computed tomography analysis. Mayo type I fractures are undisplaced, Mayo type II are displaced and stable, and Mayo type III are displaced and unstable. The last is categorized into anterior and posterior dislocations. The purpose of this study was to further clarify fracture morphology between Mayo type I, II, and III fractures.

METHODS

Three-dimensional models were created for a consecutive series of 78 patients with olecranon fractures that were evaluated with computed tomography. We determined the total number of fracture fragments, the volume and articular surface area of each fracture fragment, and the degree of displacement of the most proximal olecranon fracture fragment.

RESULTS

Displaced olecranon fractures were more comminuted than nondisplaced fractures (P = .02). Displaced fractures without ulnohumeral subluxation were smallest in terms of both volume (P < .001) and articular surface involvement (P < .001) of the most proximal olecranon fracture fragment. There was no difference in average displacement of the proximal fragment between displaced fractures with and without ulnohumeral subluxation (P = .74). Anterior olecranon fracture-dislocations created more displaced (P = .04) and smaller proximal fragments than posterior fracture-dislocations (P = .005), with comparable fragmentation on average (P = .60).

DISCUSSION/CONCLUSION

The ability to quantify volume, articular surface area, displacement, and fragmentation using quantitative 3-dimensional computed tomography should be considered when increased knowledge of fracture morphology and fracture patterns might be useful.

Greater Tuberosity Fractures: Does Fracture Assessment and Treatment Recommendation Vary Based on Imaging Modality?

BACKGROUND

For greater tuberosity fractures, 5-mm displacement is a commonly used threshold for recommending surgery; however, it is unclear if displacement can be assessed with this degree of precision and reliability using plain radiographs. It also is unclear if CT images provide additional information that might change decision making.

QUESTION/PURPOSES

We asked: (1) Does interobserver agreement for assessment of the amount and direction of fracture-fragment displacement vary based on imaging modality (radiographs only; 2-dimensional [2-D] CT images and radiographs; and 3-dimensional [3-D] and 2-D CT images and radiographs)? (2) Does the likelihood of recommending surgery vary based on imaging modality? (3) Does the level of confidence regarding the decision for treatment vary based on imaging modality?

METHODS

We invited 791 orthopaedic surgeons to complete a survey on greater tuberosity fractures. One hundred eighty (23%) responded and were randomized on a 1:1:1 basis in one of the three imaging modality groups and evaluated the same set of 22 fractures. We described age, sex, mechanism of injury, days between injury and imaging, and that patients had no comorbidities or signs of neurovascular damage for every case. One hundred sixty-four of the 180 respondents completed the study and there was an imbalance in noncompletion between the three groups (two of 67 [3.0%] in the radiograph only group; nine of 57 [16%] in the 2-D CT and radiograph group; and five of 56 [8.9%] in the 3-D CT, 2-D CT, and radiograph group; p = 0.043 by Fisher's exact test). Participants assessed amount (in millimeters) and direction (posterosuperior/posteroinferior/anterosuperior/anteroinferior/no displacement) of displacement; recommended treatment (surgical or nonoperative); and indicated their level of confidence regarding the recommended treatment on a scale from 0 to 10 for every case. Overall recommendation for treatment was expressed as a surgery score per surgeon by dividing the amount of cases they would operate on by the total number of cases (n = 22) and presented as a percentage. Confidence regarding the decision for treatment was calculated by averaging the confidence score per surgeon, ranging from 0 to 10. We compared interobserver agreement using kappa for categorical variables and intraclass correlation (ICC) for continuous variables. We used multivariable linear regression to assess difference in surgery score and confidence level between imaging groups, controlling for surgeon characteristics.

RESULTS

Interobserver agreement for assessment of amount (radiographs: ICC, 0.55, 2-D CT + radiographs ICC, 0.53, 3-D CT + 2-D CT + radiographs ICC, 0.57; p values on all comparisons >0.7) and direction (radiographs: kappa, 0.30, 2-D CT + radiographs kappa, 0.43, 3-D CT + 2-D CT + radiographs kappa, 0.40; p values for all comparisons >0.096) of displacement did not vary by imaging modality. 2-D CT and radiographs (β regression coefficient [β], 3.1; p = 0.253) and 3-D CT, 2-D CT and radiographs (β, 1.6; p = 0.561) did not result in a difference in recommendation for surgery compared with radiographs alone. 2-D CT and radiographs (β, 0.40; p = 0.021) and 3-D CT, 2-D CT and radiographs (β, 0.44; p = 0.011) were associated with slightly higher levels of confidence compared with radiographs alone.

CONCLUSIONS

Imaging modality, with the numbers evaluated, does not influence interobserver agreement of greater tuberosity fracture assessment, nor did it influence the recommendation for surgical treatment. However, surgeons did feel slightly more confident about their treatment recommendation when assessing CT images with radiographs compared with radiographs alone. Our results therefore suggest no additional value of CT scans for assessment of greater tuberosity fractures when displacement seems to be minimal on plain radiographs. CT scans could be helpful in borderline cases, or in case other fractures can be expected (eg, an occult surgical neck fracture).

LEVEL OF EVIDENCE

Level III, diagnostic study.

Distal Radius Volar Rim Fracture Fixation Using DePuy-Synthes Volar Rim Plate

Background To assess the results of distal radius fractures with the involvement of the volar rim fixed with the DePuy-Synthes Volar Rim Plate. Case Description We searched for the patients with volar rim fracture and/or volar rim fractures as part of a complex fracture fixed with a volar rim plate. Ten patients met the inclusion criteria: three patients with type 23B3, six patients with type 23C, and one patient with very distal type 23A. The mean follow-up was 14 months (range: 2-26). Fractures healed in all patients. Of the three patients with isolated volar rim fractures (type 23B3), two patients had no detectable deficits in motion. These patients had an average Gartland and Werley score of 9 (range: 2-14). Of the other seven patients (six with type 23C and one with type 23A fracture), three patients healed with full range of motion and four had some deficits in range of motion. Two patients had excellent results, three had good results, and two had fair results using the Gartland and Werley categorical rating. One patient healed with a shortened radius and ulnar impingement requiring a second surgery for ulnar head resection arthroplasty. Literature Review Results after nonoperative treatment of volar rim fractures are not satisfactory and often require subsequent corrective osteotomy. Satisfactory outcomes are achieved when the fragments are well reduced and secured regardless of the device type. Clinical Relevance Volar rim plates give an adequate buttress of the volar radius distal to volar projection of the lunate facet and do not interfere with wrist mobility. Furthermore, the dorsal fragments can be fixed securely through the volar approach eliminating the need for a secondary posterior incision. However, patients should be informed of the potential problems and the need to remove the plate if symptoms develop.

Quantitative three-dimensional computed tomography analysis of glenoid fracture patterns according to the AO/OTA classification

HYPOTHESIS/BACKGROUND

This study measures the characteristics of glenoid fractures to determine if the AO Foundation and Orthopaedic Trauma Association (AO/OTA) classification captures the most common fracture patterns. The primary null hypothesis was that surface area and degree of fragmentation do not differ among the different fracture types. Secondarily, we tested if there was a relationship between high- vs. low-energy trauma and fracture classification.

METHODS

Three-dimensional models were created for a consecutive series of 53 fractures. The fracture classifications, the number of fragments, and the fragmented articular surface area were related to the type of injury. The difference of articular surface size and number of fragments among classification groups was analyzed with the Kruskal-Wallis test.

RESULTS

There is a significant difference in fractured articular surface area among classification groups. Compared with transverse and multifragmented fractures, both anterior and posterior fractures involved significantly less of the articular surface area. High-energy trauma is associated with transverse and multifragmented fractures in 93% of the cases. It is associated with a greater number of fracture fragments and fracture of a larger percentage of the glenoid surface area, with a mean fractured surface of 60% for high-energy fractures and 25% for low-energy injuries.

DISCUSSION/CONCLUSION

Quantitative 3-dimensional CT analysis confirms that the current AO/OTA classification adequately characterizes and discriminates glenoid fracture patterns. The classification groups are related to the fragmented articular surface area and the number of fragments. Also, the mechanism of injury is related to the classification group, which supports the clinical relevance of the classification.