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

The Role of Arthroscopy in Contemporary Glenoid Fossa Fracture Fixation

Glenoid fossa fractures are rare injuries accounting for 10 to 29% of all intra-articular scapula fractures. They are usually the result of high-energy trauma, and concomitant injuries are not uncommon. Patients with glenoid fractures are admitted with shoulder pain and restricted range of motion. Although shoulder plain radiographs could establish the diagnosis, a computed tomography scan is necessary to adequately define the fracture pattern and characteristics. The most commonly used classification system is that of Ideberg (modified by Goss), which includes five glenoid fossa fracture types according to the location, extension, and complexity of the lesion. Articular surface displacement and step-off are the most important factors that should be taken under consideration when deciding for conservative or surgical management. Operative treatment includes open reduction and internal fixation through a posterior or anterior approach depending on fracture morphology and displacement. However, open surgical techniques are related to extensive soft-tissue disruption, risk of neurovascular injury, and inadequate exposure of the entire glenoid cavity. Introduction of arthroscopy could facilitate better visualization of the glenoid articular surface and improved fracture reduction. However, it is a technically demanding procedure with many challenges and pitfalls. The aim of this review is to summarize the current evidence regarding the treatment of glenoid fossa fractures and present the beneficial effect of arthroscopy in improving the quality of fracture fixation and overall functional outcomes.

Interobserver reliability of scapula fracture classifications in intra- and extra-articular injury patterns

Background

Morphology and glenoid involvement determine the necessity of surgical management in scapula fractures. While being present in only a small share of patients with shoulder trauma, numerous classification systems have been in use over the years for categorization of scapula fractures. The purpose of this study was to evaluate the established AO/OTA classification in comparison to the classification system of Euler and Rüedi (ER) with regard to interobserver reliability and confidence in clinical practice.

Methods

Based on CT imaging, 149 patients with scapula fractures were retrospectively categorized by two trauma surgeons and two radiologists using the classification systems of ER and AO/OTA. To measure the interrater reliability, Fleiss kappa (κ) was calculated independently for both fracture classifications. Rater confidence was stated subjectively on a five-point scale and compared with Wilcoxon signed rank tests. Additionally, we computed the intraclass correlation coefficient (ICC) based on absolute agreement in a two-way random effects model to assess the diagnostic confidence agreement between observers.

Results

In scapula fractures involving the glenoid fossa, interrater reliability was substantial (κ = 0.722; 95% confidence interval [CI] 0.676–0.769) for the AO/OTA classification in contrast to moderate agreement (κ = 0.579; 95% CI 0.525–0.634) for the ER classification system. Diagnostic confidence for intra-articular fracture patterns was superior using the AO/OTA classification compared to ER (p < 0.001) with higher confidence agreement (ICC: 0.882 versus 0.831). For extra-articular fractures, ER (κ = 0.817; 95% CI 0.771–0.863) provided better interrater reliability compared to AO/OTA (κ = 0.734; 95% CI 0.692–0.776) with higher diagnostic confidence (p < 0.001) and superior agreement between confidence ratings (ICC: 0.881 versus 0.912).

Conclusions

The AO/OTA classification is most suitable to categorize intra-articular scapula fractures with glenoid involvement, whereas the classification system of Euler and Rüedi appears to be superior in extra-articular injury patterns with fractures involving only the scapula body, spine, acromion and coracoid process.

Identification of recurring scapular fracture patterns using 3-dimensional computerized fracture mapping

BACKGROUND

Scapular fracture fixation and implant selection are guided by the fracture pattern and classification, which requires accurate understanding and interpretation of the fracture lines. Three-dimensional (3D) computed tomography (CT)-based fracture pattern analysis enhances a more accurate understanding of the scapular fracture patterns. The purpose of this study was to create scapular fracture maps and identify the frequent fracture patterns using 3D reconstructed CT images.

METHOD

Seventy patients treated for scapular fractures, in a single hospital, were considered for this study. Their CT images were reconstructed into 3D models and the fracture fragments were virtually reduced. The reduced 3D models were first aligned on a 3D template and 2D images were captured on the anterior, posterior, and lateral views. Then each fracture image was aligned on a corresponding 2D template and the fracture lines were transferred to the template. The 3 separate views were used to accurately capture the propagation and exit of the fractures through the scapular anatomy. These fracture lines were compiled and heat maps were generated to identify the frequent fracture zones of the scapula.

RESULT

The observed scapular fractures propagated through multiple regions of the bone. Overall, the 3 most common exit zones in the scapula were the lateral (69%), medial (67%), and superior borders (60%). More specifically, the superior lateral border, medial base of the scapula spine, spinoglenoid notch, and mid-superior border were the most frequent zones of fracture in the scapular body. Simple intra-articular fractures (transverse or oblique type) were the most common (92%) fracture type in the glenoid region.

CONCLUSION

Scapular fractures reveal repeatable patterns. The zones of recurrent fracture patterns can be identified from fracture and heat maps. Graphical plots of fracture and heat maps may assist surgical planning and implant design optimization.

Greater radial tuberosity size is associated with distal biceps tendon rupture: a quantitative 3-D CT case-control study

PURPOSE

During pronation, the distal biceps tendon and radial tuberosity internally rotate into the radioulnar space, reducing the linear distance between the radius and ulna by approximately 50%. This leaves a small space for the distal biceps tendon to move in and could possibly cause mechanical impingement or rubbing of the distal biceps tendon. Hypertrophy of the radial tuberosity potentially increases the risk of mechanical impingement of the distal biceps tendon. The purpose of our study was to determine if radial tuberosity size is associated with rupturing of the distal biceps tendon.

METHODS

Nine patients with a distal biceps tendon rupture who underwent CT were matched 1:2 to controls without distal biceps pathology. A quantitative 3-dimensional CT technique was used to calculate the following radial tuberosity characteristics: 1) volume in mm³, 2) surface area in mm², 3) maximum height in mm and 4) location (distance in mm from the articular surface of the radial head).

RESULTS

Analysis of the 3-dimensional radial tuberosity CT-models showed larger radial tuberosity volume and maximum height in the distal biceps tendon rupture group compared to the control group. Mean radial tuberosity volume in the rupture-group was 705 mm³ (SD: 222 mm³) compared to 541 mm³ (SD: 184 mm³) in the control group (p = 0.033). Mean radial tuberosity maximum height in the rupture-group was 4.6 mm (SD: 0.9 mm) compared to 3.7 mm (SD: 1.1 mm) in the control group, respectively (p = 0.011). There was no statistically significant difference in radial tuberosity surface area (ns) and radial tuberosity location (ns).

CONCLUSION

Radial tuberosity volume and maximum height were significantly greater in patients with distal biceps tendon ruptures compared to matched controls without distal biceps tendon pathology. This supports the theory that hypertrophy of the radial tuberosity plays a role in developing distal biceps tendon pathology.

LEVEL OF EVIDENCE

Level III.

Acute Fractures of the Glenoid

Glenoid fractures are unique in which they span the fields of orthopaedic traumatology and sports medicine. Treatment of glenoid fractures, whether surgical or nonsurgical, may be challenging and have long-term implications on pain and shoulder function. Plain radiographs are always indicated, and most glenoid fractures will require advanced imaging in the form of CT scan. Two general categories of glenoid fractures exist and differ in mechanism of injury, fracture morphology, and treatment. The first category is glenoid fractures with extension into the scapular neck and body. These fractures are typically from high-energy trauma and are often associated with other orthopaedic and nonorthopaedic injuries. The second category includes glenoid rim fractures, which are typically consequent of lower energy mechanisms and are associated with shoulder instability events. Treatment of glenoid rim fractures is dictated by the size and displacement of the fracture fragment and may be nonsurgical or surgical with either open and arthroscopic techniques. The purpose of this review was to discuss the current evidence on glenoid fractures regarding diagnosis, classification, management, and outcomes.

Intra- and interobserver reliability of glenoid fracture classifications by Ideberg, Euler and AO

Background

Representing 3%–5% of shoulder girdle injuries scapula fractures are rare. Furthermore, approximately 1% of scapula fractures are intraarticularfractures of the glenoid fossa. Because of uncertain fracture morphology and limited experience, the treatment of glenoid fossa fractures is difficult. The glenoid fracture classification by Ideberg (1984) and Euler (1996) is still commonly used in literature. In 2013 a new glenoid fracture classification was introduced by the AO. The purpose of this study was to examine the new AO classification in clinical practice in comparison with the classifications by Ideberg and Euler.

Methods

In total CT images of 84 patients with glenoid fossa fractures from 2005 to 2018 were included. Parasagittal, paracoronary and axial reconstructions were examined according to the classifications of Ideberg, Euler and the AO by 3 investigators (orthopedic surgeon, radiologist, student of medicine) at three individual time settings. Inter- and intraobserver reliability of the three classification systems were ascertained by computing Inter- and Intraclass (ICCs) correlation coefficients using Spearman’s rank correlation coefficient, 95%-confidence intervals as well as F-tests for correlation coefficients.

Results

Inter- and intraobserver reliability for the AO classification showed a perspicuous coherence (R = 0.74 and R = 0.79). Low to moderate intraobserver reliability for Ideberg (R = 0.46) and Euler classification (R = 0.41) was found. Furthermore, data show a low Interobserver reliability for both Ideberg and Euler classification (R < 0.2). Both the Inter- and Intraclass reliability using AO is significantly higher than those using Ideberg and Euler (p < 0.05). Using the new AO classification, it was possible to find a proper class for every glenoid fossa fracture. On average, according to Euler classification 10 of 84 fractures were not classifiable whereas to Ideberg classification 21 of 84 fractures were not classifiable.

Conclusion

The new AO classification system introduced 2013 facilitates reliable grading of glenoid fossa fractures with high inter- and intraobserver reliability in 84 patients using CT images. It should possibly be applied in order to enable a valid, reliable and consistent academic description of glenoid fossa fractures. The established classifications by Euler and Ideberg are not capable of providing a similar reliability.

Finite element analysis of intramedullary nailing and double locking plate for treating extra-articular proximal tibial fractures

Background

Proximal tibia fractures are one of the most familiar fractures. Surgical approaches are usually needed for anatomical reduction. However, no single treatment method has been widely established as the standard care. Our present study aims to compare the stress and stability of intramedullary nails (IMN) fixation and double locking plate (DLP) fixation in the treatment of extra-articular proximal tibial fractures.

Methods

A three-dimensional (3D) finite element model of the extra-articular proximal tibial fracture, whose 2-cm bone gap began 7 cm from the tibial plateau articular surface, was created fixed by different fixation implants. The axial compressive load on an adult knee during single-limb stance was imitated by an axial force of 2500 N with a distribution of 60% to the medial compartment, while the distal end was fixed effectively. The equivalent von Mises stress and displacement of the model was used as the output measures for analysis.

Results

The maximal equivalent von Mises stress value of the system in the IMN model was 293.23 MPa, which was higher comparing against that in the DLP fixation model (147.04 MPa). And the mean stress of the model in the IMN model (9.25 MPa) was higher than that of the DLP fixation system in terms of equivalent von Mises stress (EVMS) (P < 0.0001). The maximal value of displacement (sum) in the IMN system was 8.82 mm, which was lower than that in the DLP fixation system (9.48 mm).

Conclusions

This study demonstrated that the stability provided by the locking plate fixation system was superior to the intramedullary nails fixation system and served as an alternative fixation for the extra-articular proximal tibial fractures of young patients.

Comparison of 2 versus 3 dimensional fracture mapping strategies for 3 dimensional computerized tomography reconstructions of scapula neck and body fractures

Fracture mapping has been used in the understanding of injury patterns in different bones. To our knowledge, there are no applications of this technique using three-dimensional (3D) morphologic fracture characteristics. Previously, scapula fractures were mapped by transferring information from 3D computed tomography to a two-dimensional (2D) template. Cole et al. determined that 3D Computerized Tomography (CT) scans were more reliable compared to plain radiographs in terms of scapular angulation, translation, and glenopolar angle measurements. Thus, we hypothesized that if there is a difference between fracture lines drawn in 3D and in 2D, then the 3D mapping would yield more accurate fracture patterns. We completed a retrospective, comparative study (evidence level III) utilizing CT imaging from a single center scapular registry. We studied ten patients with scapula fractures in whom bilateral CT scans were obtained. Fractures were mapped both two and three-dimensionally, and we measured deviations between the fracture lines that were drawn with each approach. The measured deviations ranged from 10.4 mm to 28.0 mm when comparing 2D versus 3D techniques, with the mean deviation being 4.0 mm and 10.4 mm, respectively. Half of the 2D renderings possessed hidden fracture lines that were later revealed on 3D imaging. Three-dimensional renderings were more accurate when compared to 2D fracture mapping methods. This more accurate technique will allow for better understanding of 3D morphology and provide a basis for future fracture mapping in any bone. Accurate mapping is important because surgical approach, reduction, fixation, and implant design and selection are based on fracture patterns. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:265-271, 2018.

Osteochondritis dissecans of the capitellum: lesion size and pattern analysis using quantitative 3-dimensional computed tomography and mapping technique

BACKGROUND

The goals of this study were to evaluate the reliability of a quantitative 3-dimensional computed tomography (Q3DCT) technique for measurement of the capitellar osteochondritis dissecans (OCD) surface area, to analyze OCD distribution using a mapping technique, and to investigate associations between Q3DCT lesion quantification and demographic characteristics and/or clinical examination findings.

METHODS

We identified patients with capitellar OCD who presented to our orthopedic sports medicine practice between January 2001 and January 2016 and who had undergone a preoperative computed tomography scan (slice thickness ≤1.25 mm). A total of 17 patients with a median age of 15 years (range, 12-23 years) were included in this study. Three-dimensional polygon models were reconstructed after osseous structures were marked in 3 planes. Surface areas of the OCD lesion as well as the capitellum were measured. Observer agreement was assessed with the intraclass correlation coefficient (ICC). Heat maps were created to visualize OCD distribution.

RESULTS

Measurements of the OCD surface area showed almost perfect intraobserver agreement (ICC, 0.99; confidence interval [CI], 0.98-0.99) and interobserver agreement (ICC, 0.93; CI, 0.86-0.97). Measurements of the capitellar surface area also showed almost perfect intraobserver agreement (ICC, 0.97;CI, 0.91-0.99) and interobserver agreement (ICC, 0.86; CI, 0.46-0.96). The median OCD surface area was 101 mm² (range, 49-217 mm²). On the basis of OCD heat mapping, the posterolateral zone of the capitellum was most frequently affected. OCDs in which the lateral wall was involved were associated with larger lesion size (P = .041), longer duration of symptoms (P = .030), and worse elbow extension (P = .013).

CONCLUSIONS

The ability to quantify the capitellar OCD surface area and lesion location in a reliable manner using Q3DCT and a mapping technique should be considered when detailed knowledge of lesion size and location is desired.

Pathoanatomy and computed tomography classification of glenoid fossa fractures based on ninety patients

PURPOSE

The aim of the article is to present the pathoanatomy and a new classification of glenoid fractures developed on the basis of analysis of 3D computed tomography (CT) examinations and intra-operative findings.

MATERIALS AND METHODS

The study group comprised 90 patients (69 men and 21 women) who sustained glenoid fractures. Mean patient age was 47 years (17-92). In 77 nonpolytraumatised patients, anteroposterior (AP) radiographs of the affected shoulder girdle were taken, including Neer I and II views. All 90 patients underwent CT examination, combined in 73 of them with 3D CT reconstruction including subtraction of the humeral head, ribs and clavicle, from the anterior and posterolateral views. In total, 52 patients (58 %) were operated on and 38 42 %) were treated non-operatively.

RESULTS

In total, five basic types of injuries to the glenoid were identified based on analysis of the separated portion of the glenoid fossa: including fractures of the superior glenoid (14 cases, 16 %), the anterior glenoid (23 cases, 23 %), the posterior rim of the glenoid (5 cases, 6 %), the inferior glenoid (38 cases, 42 %) and the entire glenoid (10 cases, 11 %).

CONCLUSION

The proposed classification of glenoid fractures defines five basic types of fractures verified by 3D CT reconstructions and intra-operative findings. It respects the anatomical architecture of scapula, fracture mechanism, associated injuries to the shoulder girdle and, where appropriate, the preferred surgical approach.