Surgical anatomy of multipart fractures of the proximal humerus

Cortical thickness analysis of the proximal humerus

BACKGROUND

Structural changes within the proximal humerus influence the mechanical properties of the entire bone and predispose to low-energy fractures with complex patterns. The aim of the present study was to measure the cortical thickness in different regions of the proximal humerus.

METHODS

Thirty-seven proximal humeri were analyzed using novel engineering software to determine cortical thickness in 10 distinct anatomical zones.

RESULTS

The cortical thickness values ranged from 0.33 mm to 3.5 mm. Fifteen specimens demonstrated a consistent pattern of progressive cortical thinning that increased between the bicipital groove (thickest), the lesser tuberosity and the greater tuberosity (thinnest). Fifteen humeri were characterized by a progressive increase in cortical thickness between the greater tuberosity (thinnest), the bicipital groove and lesser tuberosity (thickest). The diaphysis exhibited the thickest cortical zone in 27 specimens, whereas the articular surface possessed the thinnest cortex in 18 cases.

CONCLUSIONS

In conclusion, this is the first study to comprehensively assess cortical thickness of the humeral head. Our findings suggest that proximal humeral fractures occur along lines of cortical thinning and are displaced by the hard glenoid bone. The identification of specific areas of thick cortices may improve pre-operative planning and optimize fracture fixation.

The complexity of proximal humeral fractures is age and gender specific

BACKGROUND

Studies that investigated possible associations between the complexity of proximal humeral fractures and patient characteristics are rare. We hypothesized that the grade of fracture complexity may correlate with age and gender of hospitalized, adult patients.

METHODS

Based on the Neer classification, we defined four radiological grades of fracture complexity. The data of adult patients that were treated during a 9-year period at a German hospital serving a town of 80,000 inhabitants was reviewed.

RESULTS

Seven hundred and eighty fractures were evaluated [518 female/262 male (66.41/33.59 %), average age 64.2 years (range 17.4-99.2)]. During the study period, the number of fractures increased to 167 %. Almost two-thirds of the patients were females and older than 60 years. Of all fractures, 86 % were displaced fractures. In patients younger than 60 years, 1.99-fold more complex fractures occurred in males (32.4 %) than in females (16.2 %). In contrast, in patients older than 60 years, 1.72-fold more complex fractures occurred in females (54.1 %) than in males (31.5 %). There was a significant association between low-energy trauma and female gender older than 60 years.

CONCLUSIONS

Our study demonstrated an overall increase of displaced proximal fractures. The vast majority of patients with more complex fractures consisted of female patients older than 60 years.

AST classification of proximal humeral fractures: introduction and interobserver reliability assessment

BACKGROUND

This article introduces an alphanumeric AST (Articular, Surgical neck, Tuberosities) classification of proximal humeral fractures, based on the number, localization, and displacement of articular and extra-articular fragments. All possible cases of proximal humeral fractures can be assessed from a single figure using this classification. The aim of the study was thus to describe the AST classification and to assess interobserver reliability.

METHODS

This classification is based on a single figure, allowing an easy description of the anatomic variants of different proximal humeral fractures. The severity of the fracture is determined by the fragment displacement in angular degrees and the major linear displacement in millimeters. AST reproducibility was assessed and compared with Neer, AO, and Duparc classifications, commonly used in clinical practice. The interobserver agreement was measured with Cohen's kappa coefficients and their 95% confidence intervals.

RESULTS

Thirteen independent observers analyzed a total of 64 X-rays. Overall kappa coefficients were 0.34, 0.29, 0.24, and 0.25 for AST, Neer, AO, and Duparc classifications, respectively.

CONCLUSION

The AST classification, which is easier to use because it is based on only one figure, is at least as reproducible as other proximal humeral fracture classifications.

Proximal humeral fracture classification systems revisited

HYPOTHESIS

This study evaluated several classification systems and expert surgeons' anatomic understanding of these complex injuries based on a consecutive series of patients. We hypothesized that current proximal humeral fracture classification systems, regardless of imaging methods, are not sufficiently reliable to aid clinical management of these injuries.

MATERIALS AND METHODS

Complex fractures in 96 consecutive patients were investigated by generation of rapid sequence prototyping models from computed tomography Digital Imaging and Communications in Medicine (DICOM) imaging data. Four independent senior observers were asked to classify each model using 4 classification systems: Neer, AO, Codman-Hertel, and a prototype classification system by Resch. Interobserver and intraobserver κ coefficient values were calculated for the overall classification system and for selected classification items.

RESULTS

The κ coefficient values for the interobserver reliability were 0.33 for Neer, 0.11 for AO, 0.44 for Codman-Hertel, and 0.15 for Resch. Interobserver reliability κ coefficient values were 0.32 for the number of fragments and 0.30 for the anatomic segment involved using the Neer system, 0.30 for the AO type (A, B, C), and 0.53, 0.48, and 0.08 for the Resch impaction/distraction, varus/valgus and flexion/extension subgroups, respectively. Three-part fractures showed low reliability for the Neer and AO systems.

DISCUSSION

Currently available evidence suggests fracture classifications in use have poor intra- and inter-observer reliability despite the modality of imaging used thus making treating these injuries difficult as weak as affecting scientific research as well. This study was undertaken to evaluate the reliability of several systems using rapid sequence prototype models.

CONCLUSION

Overall interobserver κ values represented slight to moderate agreement. The most reliable interobserver scores were found with the Codman-Hertel classification, followed by elements of Resch's trial system. The AO system had the lowest values. The higher interobserver reliability values for the Codman-Hertel system showed that is the only comprehensive fracture description studied, whereas the novel classification by Resch showed clear definition in respect to varus/valgus and impaction/distraction angulation.

Updated classification system for proximal humeral fractures

Proximal humeral fractures can restrict daily activities and, therefore, deserve efficient diagnoses that minimize complications and sequels. For good diagnosis and treatment, patient characteristics, variability in the forms of the fractures presented, and the technical difficulties in achieving fair results with surgical treatment should all be taken into account. Current classification systems for these fractures are based on anatomical and pathological principles, and not on systematic image reading. These fractures can appear in many different forms, with many characteristics that must be identified. However, many current classification systems lack good reliability, both inter-observer and intra-observer for different image types. A new approach to image reading, following a well-designed set and sequence of variables to check, is needed. We previously reported such an image reading system. In the present study, we report a classification system based on this image reading system. Here we define 21 fracture characteristics and apply them along with classical Codman approaches to classify fractures. We base this novel classification system for classifying proximal humeral fractures on a review of scientific literature and improvements to our image reading protocol. Patient status, fracture characteristics and surgeon circumstances have been important issues in developing this system.

Four-segment classification of proximal humeral fractures revisited: a multicenter study on 509 cases

BACKGROUND

The 4-segment classification of Neer (1970) was revised in 2002 with the inclusion of valgus-impacted fractures. However, the range of possible fracture types covered by this classification is not clear. With the aim to clarify actual fracture patterns of the proximal humerus, a retrospective, multicenter study was conducted.

METHODS

We retrospectively reviewed 509 cases for which anteroposterior and trans-scapular lateral views had been taken at the time of injury. Initially, three examiners from three facilities, independently read the radiographs of each case. In the second and third phases, for more difficult cases, consensus opinions were reached.

RESULTS

We found that 501 (98%) of the 509 fractures had an appropriate category in the revised Neer classification. There were 185 cases (36%) of one-part fractures, followed by 156 cases (31%) of 2-part surgical neck fracture, 60 cases (12%) of 2-part greater tuberosity fracture (dislocation included), 45 cases (8.8%) of 3-part fracture involving the greater tuberosity and the surgical neck (dislocation included), 31 cases (6.1%) of 4-part fracture (dislocation included), and 17 cases (3.3%) of valgus-impacted fracture.Eight fractures (1.6%) could not be classified with the revised Neer classification. They were "3-part" fractures in terms of the number of displaced segments but had a complete anatomic neck fracture.

CONCLUSION

We conclude that it would be appropriate to use the revised Neer classification in clinical practice. We would emphasize that, when there are 3 displaced segments, close attention should be paid to the fracture line on the anatomic neck.

LEVEL OF EVIDENCE

Level 4; Diagnostic study, case series.

Classification and imaging of proximal humerus fractures

The decision to operate and the selection of the appropriate surgical modality for proximal humerus fractures are largely based on the fracture pattern. Understanding the particular fracture pattern in each case is complicated. Most well-accepted classification systems were developed based on radiographs complemented by intraoperative findings. Three-dimensional reconstructions based on CT currently available in most institutions allow a much better understanding of complex fractures. Modern thinking about fracture classification probably should be revisited in the light of improved imaging techniques.

Radiographic evaluation of the shoulder

Imaging evaluation of shoulder disorders should begin with radiographs. Several radiographic projections have been developed to best show areas affected by particular clinical disorders. This paper reviews the radiographic examinations that are used at our hospital for evaluating arthritis, impingement, trauma and instability. The techniques used to obtain each of these radiographs are briefly described to better understand the resulting images. An organized approach to assessment of these radiographs is delineated including evaluation of the ABCs (alignment, bone density, cartilage spaces and soft tissues). The expected radiographic findings in normal individuals and in patients with common abnormal conditions are reviewed.

Inter- and intraobserver reliability of the MTM-classification for proximal humeral fractures: a prospective study

BACKGROUND

A precise modular topographic-morphological (MTM) classification for proximal humeral fractures may address current classification problems. The classification was developed to evaluate whether a very detailed classification exceeding the analysis of fractured parts may be a valuable tool.

METHODS

Three observers classified plain radiographs of 22 fractures using both a simple version (fracture displacement, number of parts) and an extensive version (individual topographic fracture type and morphology) of the MTM classification. Kappa-statistics were used to determine reliability.

RESULTS

An acceptable reliability was found for the simple version classifying fracture displacement and fractured main parts. Fair interobserver agreement was found for the extensive version with individual topographic fracture type and morphology.

CONCLUSION

Although the MTM-classification covers a wide spectrum of fracture types, our results indicate that the precise topographic and morphological description is not delivering reproducible results. Therefore, simplicity in fracture classification may be more useful than extensive approaches, which are not adequately reliable to address current classification problems.

A combined fracture of the greater and lesser tuberosity with head shaft continuity in the proximal humerus

We treated a combined fracture of the greater and lesser tuberosity with head shaft continuity in the proximal humerus. This case is impossible to classify in three of the classifications, the Neer classification, AO Müller classification, or Jakob classification. However, this case has been described as fracture types in two different categories in the Codman classification. Based on our experience with this case, we concluded that both the plain radiographs and the CT scans were necessary to make a correct diagnosis and classify the fractures of the proximal humerus.

Fractures of the greater tuberosity of the humerus

Isolated fractures of the greater tuberosity of the humerus can occur in anterior shoulder dislocations or as the result of an impaction injury against the acromion or superior glenoid. Greater tuberosity fractures may be associated with partial-thickness rotator cuff tears and labral tears, which may be the cause of persistent pain after fracture healing. Nondisplaced and minimally displaced fractures are typically treated successfully nonsurgically. Surgical fixation is recommended for fractures with >5 mm of displacement in the general population or >3 mm of displacement in active patients involved in frequent overhead activity. Open surgical repair is performed with suture or screw fixation. Recently, arthroscopic techniques have produced promising results. Careful follow-up and supervised rehabilitation optimize results after both nonsurgical and surgical treatment.

Proposed protocol for reading images of humeral head fractures

Fractures of the proximal humerus can be treated effectively but require proper characterization. None of the existing classifications intended to facilitate characterization have been satisfactory. We studied proximal humerus fractures using radiographs alone and radiographs plus computed tomography scans to ascertain which imaging studies were most useful to characterize these fractures. We designed an assessment protocol consisting of 17 parameters divided in four groups: cephalodiaphyseal relationship (six parameters), cephalotuberosity relationship (six parameters), humeral head (two parameters), and fracture fragment description (three parameters). The computed tomography scans were assessed using 11 parameters (the same parameters used for assessing radiographs except for the six cephalodiaphyseal parameters). Four observers analyzed the parameters in 30 selected fractures with biplanar radiographic projections (30 patients) and computed tomography scans (22 patients) on two occasions. We found good interobserver reliability and intraobserver reliability with radiographs alone for the cephalodiaphyseal parameters. The best interobserver reliabilities with radiographs plus computed tomography scans were with the number of fragments, displacement of the lesser tuberosity, and extraarticular or articular fractures. Computed tomography allows better assessment of some parameters in characterizing proximal humeral fractures. The use of a structured protocol in reading images seems useful and allows better reliability than reported for other approaches.

LEVEL OF EVIDENCE

Diagnostic study, Level III (study of nonconsecutive patients without consistently applied reference "gold" standard). See the Guidelines for Authors for a complete description of levels of evidence.

Proximal humerus fractures

Proximal humerus fractures are common injuries. Knowledge of local anatomy is paramount in the evaluation and treatment of these injuries. Information regarding humeral head vascularity, fracture patterns, bone quality, and overall geometry have direct implications for nonoperative treatment, internal fixation, and hemiarthroplasty. The ascending branch of the anterior circumflex artery perfuses most of the humeral head. When fractured, the greater tuberosity tends to displace posterosuperiorly, the lesser tuberosity and the shaft displace medially, and the head may be pulled by the attached tuberosity, impacted into valgus, or in more severe cases dislocated, impacted, or divided. Internal fixation of two-part, three-part, and selected four-part fractures may be compromised by local osteopenia; knowledge of the location of the strongest bone in the proximal humerus combined with the use of fixed-angle devices and occasionally bone graft or substitutes has improved the outcome of osteosynthesis. When the humeral head cannot be preserved, successful hemiarthroplasty requires tuberosity union and anatomic restoration of the overall geometry of the proximal humerus in terms of height, retroversion, and head-tuberosity relationships.