The effect of coronoid fractures on elbow kinematics and stability

Type II coronoid fracture in a terrible triad elbow: An experimental study of the elbow kinematics using dynamic radiostereometric analysis

BACKGROUND

The aim of this study was to evaluate the elbow kinematics with and without a Regan-Morrey type II coronoid fracture in an experimental setting of terrible triad injury with intact collateral ligaments and radial head arthroplasty.

METHODS

Eight human donor arms were examined following radial head arthroplasty with and without a 1/3 coronoid fracture by CT and dynamic radiostereometry during elbow flexion with the forearm in unloaded neutral position, and in supinated- and pronated position without and with 10 N either varus or valgus load, respectively. The elbow kinematics were described using anatomical coordinate systems.

FINDINGS

The coronoid fracture changed the elbow kinematics. In the valgus loaded pronated forearm position, the radius shifted mean 1.7 mm (95 %CI 0.2; 3.2) posterior, and the ulna shifted mean 0.6 mm (95 %CI 0.0; 1.2) in the radial direction. In the unloaded supinated position, the radius shifted 0.8 mm (95 %CI 0.0; 1.5) posterior and 1.0 mm (95 %CI 0.4; 1.6) in the ulnar direction, while the ulna shifted 0.7 mm (95 %CI 0.1; 1.4) posterior. In the varus loaded supinated position, the radius shifted 1.4 mm (95 %CI 0.2; 2.6) in the ulnar direction.

INTERPRETATION

The Regan-Morrey type II coronoid fracture imposed slight kinematic changes to the elbow joint, which may not be clinically relevant. This indicates that a type II coronoid fracture may not need fixation in the setting of optimal radial head arthroplasty with intact collateral ligaments. However, elbow stability should be evaluated intraoperatively in every terrible triad case.

A proposal for computed tomography-based algorithm for the management of radial head and neck fractures: the Proximal and Articular Radial fractures Management (PARMa) classification

Background

Owing to the great variety of fracture patterns and limitations of the standard radiographic investigation, all the already available classification systems for radial head and neck fractures (RHNFs) are limited by a poor-to-moderate degree of intraobserver and interobserver reliability. Although computed tomography (CT) is being increasingly used to better understand the fracture characteristics, a CT-based classification system of RHNFs is still lacking. Therefore, in this agreement study, we aimed to propose a classification system based on two-dimensional and three-dimensional (2D/3D) CT to test the hypothesis that this classification has good intraobserver and interobserver reliability. We have also provided a treatment algorithm.

Methods

Our proposed classification-Proximal and Articular Radial fractures Management (PARMa)-is based on 2D/3D CT imaging. It is divided into four types based on different fractures patterns. The 2D/3D scans of 90 RHNFs were evaluated in a blinded fashion by eight orthopedic and one radiology consultant, according to the proposed classification. The first phase of observation aimed to estimate the interobserver agreement. The second phase involved a new observation, 4 weeks after the first analysis, and estimated the intraobserver reliability. The standard radiographs of these 90 fractures were also evaluated by the same observers, with the same timing and methods, based on the same classification. Cohen's Kappa was applied for intraobserver agreement. Fleiss's Kappa was used both within and among the evaluators. Kendall's coefficient of concordance was employed to determine the strength of association among the appraisers' rankings. Furthermore, Krippendorff's alpha was chosen as an adjunctive analysis to assess between evaluators' agreement.

Results

For the intraobserver agreement, Fleiss' Kappa statistics confirmed the consistency (overall kappa values: 0.70-0.82). Cohen's Kappa statistics aligned with Fleiss' Kappa, with similar kappa values and significant P values (P < .001). For interobserver agreement, Fleiss' Kappa statistics for between appraisers showed moderate-to-substantial agreement, with kappa values ranging from 0.54 to 0.82 for different responses. The results relating to the appraisers' observation of standard radiographs showed that the overall Fleiss' Kappa values for intraobserver agreement ranged from 0.34 to 0.82, whereas Fleiss' Kappa statistics for interobserver agreement ranged from 0.40 to 0.69.

Conclusions

The proposed classification system is expected to be reliable, reproducible, and useful for preoperative planning and surgical management. Both 2D and 3D CT allow the identification of the magnitude and position of displacement and articular surface involvement.

Creation of a replicable anatomic model of terrible triad of the elbow

BACKGROUND

Terrible triad of the elbow (TTE) is a complex dislocation associating radial head (RH) and coronoid process (CP) fractures. There is at present no reproducible anatomic model for TTE, and pathophysiology is unclear. The main aim of the present study was to create and validate an anatomic model of TTE. Secondary objectives were to assess breaking forces and relative forearm rotation with respect to the humerus before dislocation.

METHODS

An experimental comparative study was conducted on 5 fresh human specimens aged 87.4 ± 8.6 years, testing 10 upper limbs. After dissection conserving the medial and lateral ligaments, interosseous membrane and joint capsule, elbows were reproducibly positioned in maximal pronation and 15° flexion, for axial compression on a rapid (100 mm/min) or slow (10 mm/min) protocol, applied by randomization between the two elbows of a given cadaver, measuring breaking forces and relative forearm rotation with respect to the humerus before dislocation.

RESULTS

The rapid protocol reproduced 4 posterolateral and 1 divergent anteroposterior TTE, and the slow protocol 5 posterolateral TTE. Mean breaking forces were 3,126 ± 1,066 N for the lateral collateral ligament (LCL), 3,026 ± 1,308 N for the RH and 2,613 ± 1,120 N for the CP. Comparing mean breaking forces for all injured structures in a given elbow on the rapid protocol found a p-value of 0.033. Comparison of difference in breaking forces in the three structures (LCL, RH and CP) between the slow and rapid protocols found a mean difference of -4%. Mean relative forearm rotation with respect to the humerus before dislocation was 1.6 ± 1.2° in external rotation.

CONCLUSIONS

We create and validate an anatomic model of TTE by exerting axial compression on an elbow in 15° flexion and maximal pronation at speeds of 100 and 10 mm/min.

Diagnosis and Treatment of Varus Posteromedial Rotational Instability of the Elbow Joint in Children: Re-Understanding of the Injury Mechanism Associated With Coronoid Process Fractures

PURPOSE

To investigate the injury mechanism, diagnosis, and treatment of varus-posteromedial rotational instability of the elbow joint in children.

METHODS

According to the diagnostic criteria of varus posteromedial rotational instability of elbow joint, 16 children with coronoid process fractures treated in our department from July 2013 to July 2017 were re-evaluated. There were 14 males and 2 females, aged 7 to 14 years, with an average age of 11.6 years. Eight cases on left and 8 cases on right side. An associated elbow dislocation occurred in 8 of 16 cases. Nine patients were treated with a lateral soft tissue repair only. In 7 other patients in addition to the lateral soft tissue repair, the coronoid process fractures were treated with open reduction and fixation. At the last clinical follow-up, each elbow joint range of motion was recorded, radiographs were obtained, and functional performance was evaluated by the Mayo elbow performance score (MEPS).

RESULTS

The average follow-up time was 81.9 months for the 9 patients treated with lateral elbow soft tissue repair. At the last follow-up, 2 of the patients had MEPS scores as excellent, 1 was good, and 6 were rated as moderate or poor. Four patients had a cubitus varus deformity. The average follow-up time was 30.3 months for the 7 patients treated with both soft tissue repair and coronoid fracture stabilization. The elbow joint MEPS scores for each of these 7 patients was excellent at the last follow-up, and no complications such as cubitus varus occurred.

CONCLUSION

The results of the study suggest that children could also develop elbow varus-posterior medial rotational instability injuries under the same mechanism. Although the morbidity rate is low, due to insufficient understanding of the injury mechanism, it is prone to missed diagnosis, misdiagnosis, and delayed treatment, resulting in severe complications such as elbow instability, dislocation, traumatic arthritis, and elbow stiffness. On the contrary, according to the treatment principle of the posterior medial rotational instability of the elbow joint in adult, while the lateral repair is carried out, strong and effective reduction and fixation of the coronoid process fractures are adopted, it is expected that such children with rare elbow injuries can obtain excellent treatment outcomes.

Complex Elbow Fracture-Dislocations: An Algorithmic Approach to Treatment

Elbow stability arises from a combination of bony congruity, static ligamentous and capsular restraints, and dynamic muscular activation. Elbow trauma can disrupt these static and dynamic stabilizers leading to predictable patterns of instability; these patterns are dependent on the mechanism of injury and a progressive failure of anatomic structures. An algorithmic approach to the diagnosis and treatment of complex elbow fracture-dislocation injuries can improve the diagnostic assessment and reconstruction of the bony and ligamentous restraints to restore a stable and functional elbow. Achieving optimal outcomes requires a comprehensive understanding of pertinent local and regional anatomy, the altered mechanics associated with elbow injury, versatility in surgical approaches and fixation methods, and a strategic rehabilitation plan.

Coronoid fractures and complex elbow instability: current concepts

Fractures of the coronoid process typically occur as part of more complex injury patterns, such as terrible triads, trans-olecranon fracture-dislocations, posteromedial rotatory injuries or Monteggia-like lesions. Each pattern is associated with a specific type of coronoid fracture with regard to shape and size and specific soft-tissue lesions. O' Driscoll classification incorporates those associations identifying three major types of fractures: tip, anteromedial facet, and basal fractures. The objective of this study is to review the most common types of complex elbow instability, identify the indications for coronoid fixation and guide the appropriate management. Tip fractures as those seen in terrible triads can conditionally left untreated provided that elbow stability has been restored after radial head fixation and ligaments repair. Anteromedial facet fractures benefit from a buttress plate, while large basilar fractures can be effectively secured with posteroanterior screws. Coronoid reconstruction with a graft should be considered in post-traumatic cases of chronic coronoid deficiency.

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.

Coronoid fractures and traumatic elbow instability

The coronoid process is key to concentric elbow alignment. Malalignment can contribute to post-traumatic osteoarthritis. The aim of treatment is to keep the joint aligned while the collateral ligaments and fractures heal. The injury pattern is apparent in the shape and size of the coronoid fracture fragments: (1) coronoid tip fractures associated with terrible triad (TT) injuries; (2) anteromedial facet fractures with posteromedial varus rotational type injuries; and (3) large coronoid base fractures with anterior (trans-) or posterior olecranon fracture dislocations. Each injury pattern is associated with specific ligamentous injuries and fracture characteristics useful in planning treatment. The tip fractures associated with TT injuries are repaired with suture fixation or screw fixation in addition to repair or replacement of the radial head fracture and reattachment of the lateral collateral ligament origin. Anteromedial facet fractures are usually repaired with a medial buttress plate. If the elbow is concentrically located on computed tomography and the patient can avoid varus stress for a month, TT and anteromedial facet injuries can be treated nonoperatively. Base fractures are associated with olecranon fractures and can usually be fixed with screws through the posterior plate or with an additional medial plate. If the surgery makes elbow subluxation or dislocation unlikely, and the fracture fixation is secure, elbow motion and stretching can commence within a week when the patient is comfortable.

Coronoid Fracture Reconstruction with Ipsilateral Olecranon Osteoarticular Autograft in the Acute Setting: A Case Report

CASE

An 18-year-old male polytrauma patient sustained a high-energy posterior fracture dislocation of his left elbow associated with a comminuted and irreparable O'Driscoll type 2 subtype 3 anteromedial facet coronoid fracture. He underwent early coronoid reconstruction using ipsilateral olecranon osteoarticular autograft with incorporation of the sublime tubercle attachment of the medial collateral ligament and repair of the lateral ulnar collateral ligament. A 3-year follow-up revealed a functional, painless, congruent, and stable elbow.

CONCLUSION

Early reconstruction of a highly comminuted coronoid fracture may be a useful salvage option for the polytrauma patient, thereby avoiding complications associated with late reconstruction of posttraumatic elbow instability.

Three-dimensional cortical and trabecular bone microstructure of the proximal ulna

INTRODUCTION

The three-dimensional (3D) microstructure of the cortical and trabecular bone of the proximal ulna has not yet been described by means of high-resolution 3D imaging. An improved characterization can provide a better understanding of their relative contribution to resist impact load. The aim of this study is to describe the proximal ulna bone microstructure using micro-computed tomography (micro-CT) and relate it to gross morphology and function.

MATERIALS AND METHODS

Five dry cadaveric human ulnae were scanned by micro-CT (17 μm/voxel, isotropic). Both qualitative and quantitative assessments were performed on sagittal image stacks. The cortical thickness of the trochlear notch and the trabecular bone microstructure were measured in the olecranon, bare area and coronoid.

RESULTS

Groups of trabecular struts starting in the bare area, spanning towards the anterior and posterior side of the proximal ulna, were observed; within the coronoid, the trabeculae were orthogonal to the joint surface. Consistently among the ulnae, the coronoid showed the highest cortical thickness (1.66 ± 0.59 mm, p = 0.04) and the olecranon the lowest (0.33 ± 0.06 mm, p = 0.04). The bare area exhibited the highest bone volume fraction (BV/TV = 43.7 ± 22.4%), trabecular thickness (Tb.Th = 0.40 ± 0.09 mm) and lowest structure model index (SMI = - 0.28 ± 2.20, indicating plate-like structure), compared to the other regions (p = 0.04).

CONCLUSIONS

Our microstructural results suggest that the bare area is the region where most of the loading of the proximal ulna is concentrated, whereas the coronoid, together with its anteromedial facet, is the most important bony stabilizer of the elbow joint. Studying the proximal ulna bone microstructure helps understanding its possible everyday mechanical loading conditions and potential fractures.

LEVEL OF EVIDENCE

N.A.

Finite element analysis of coronoid prostheses with different fixation methods in the treatment of comminuted coronoid process fracture

BACKGROUND

Comminuted fractures of the coronoid process significantly compromise the stability and function of the elbow joint. Reconstruction of the coronoid process with a prosthesis has been suggested as an alternative to restore the architecture. The purpose of this study was to investigate the strength and stability of various methods for the fixation of a coronoid prosthesis by finite element analysis.

MATERIALS AND METHODS

A coronoid prosthesis was designed based on the morphological information from computed tomography images acquired from 64 subjects in whom the top 40% of the coronoid process height was replaced. Four methods for the fixation of the prosthesis were suggested: (1) a double 2.0-mm fixation bolt, anterior to posterior; (2) a double 2.5-mm fixation bolt, anterior to posterior; (3) a single 4.0-mm fixation bolt, posterior to anterior; (4) a single 4.5-mm fixation bolt, posterior to anterior. The integrated prosthesis-bone constructs were analyzed via the finite element analysis of 10 simulated proximal ulna models with loading applied along the axis of the humerus and with three different elbow flexion angles (30°, 90°, and 130°). The maximum principal stress and the total deformation were quantified and compared.

RESULTS

A coronoid prosthesis was developed. The maximum principal stress of the fixation bolts occurred around the neck of the fixation bolt. For a comparison of the strengths of the four fixation methods, the maximum principal stress was the lowest for fixation using a single 4.5-mm fixation bolt. The value of the maximum principal stress significantly decreased with increased elbow flexion angle for all fixation methods. The maximum deformation of the fixation bolts occurred at the head of the fixation bolt. For a comparison of the maximum deformations in the four fixation methods, the maximum deformation was the lowest for fixation using a single 4.5-mm fixation bolt. The value of the maximum deformation significantly decreased with increased elbow flexion angle for all fixation methods.

CONCLUSIONS

The present study suggested that fixation of a coronoid prosthesis with a single 4.5-mm fixation bolt from posterior to anterior is an excellent option in terms of the strength and stability. Level of Evidence Experimental study.

The coronoid opening angle: a novel radiographic technique to assess bone loss in coronoid trauma

BACKGROUND

Elbow fracture dislocations are complex injuries that often require surgical treatment in order to obtain a stable and congruent elbow joint. The coronoid plays a key role in the stability of this joint. Accurately identifying the degree of coronoid bone loss in the setting of traumatic elbow injuries is challenging. The purpose of this study is to describe a new radiographic measure, the coronoid opening angle (COA), to assist in estimating bone loss in these challenging fractures.

METHODS

Radiographs were drawn from a regional database in a consecutive fashion. Candidate radiographs were excluded on the basis of radiographic evidence of degenerative changes, previous surgery or injury, bony deformity, and inadequate lateral view of the elbow. Normal COA, coronoid height, and calculated COA at varying amounts of bone loss were determined by 3 reviewers.

RESULTS

A total of 120 subjects were included. The normal coronoid opening angle was 34° (95% CI 32.9°-34.0°) and the coronoid height, 18.8 mm (18.1-19.6). Ninety-five percent of the population had an opening angle greater than 29° (95% CI 27.2°-29°). The COA limit was calculated at 20%, 33%, and 50% of baseline coronoid height corresponding to degree of bone loss. Coronoid opening angles of 24°, 20°, and 16°, respectively, indicate the minimum bone loss of interest in 95% of the population. The intraclass correlation coefficient was found to be 0.89 or higher.

CONCLUSION

In the setting of elbow trauma, it is often challenging to predict the amount of coronoid bone loss. The coronoid opening angle is a new technique and an adjunct for lateral elbow radiographs to predict the minimum coronoid bone loss. This can be used to guide clinical decision making, aid in predicting instability, and guide treatment. Future research will aim to validate this tool in the clinical trauma setting.

Greater sigmoid notch dysplasia causing elbow instability: Lateral ligament reconstruction and Stamp osteotomy

The coronoid is one of the elbow's primary static stabilisers, and the importance of reconstruction following fracture with instability has been established. In the developing elbow, instability can lead to greater sigmoid notch dysplasia that can make reconstruction challenging. A novel technique to improve osseous stability with an opening wedge 'stamp osteotomy' reconstruction of the coronoid is described combined with a lateral ligament reconstruction, in two patients with recurrent posteromedial rotatory instability. The technique improves congruity and coverage of the greater sigmoid notch with the trochlea whilst maintaining articular cartilage. Extra-articular iliac crest bone graft is used to maintain the position with buttress plate support. The surgical technique is described and the clinical and radiographic outcome reported in two patients. Level of evidence: IV.

[Coronoid reconstruction with autologous iliac crest bone graft in chronic elbow instability through a medial approach]

OBJECTIVE

Neutralizing a posteromedial rotatory instability (PMRI) caused by coronoid deficiency by restoration of the humeroulnar joint surface with an autologous iliac crest bone graft.

INDICATIONS

Surgery is indicated in patients with chronic deficiency of the anteromedial facet of the coronoid with subsequent PMRI.

CONTRAINDICATIONS

Coronoid reconstruction is not recommended in patients with advanced osteoarthritis of the elbow caused by subluxation of the humeroulnar joint. General contraindications like acute infection, pregnancy and lack of operability should also be taken into account.

SURGICAL TECHNIQUE

First, a medial approach is established and the base of the coronoid is prepared. Afterwards an autologous iliac crest bone graft is placed onto the defect and secured by screws or a plate. In addition, a reconstruction of the anterior bundle of the medial collateral ligament with an autologous tendon graft is performed.

POSTOPERATIVE MANAGEMENT

An elbow orthesis is worn for 6 weeks after surgery to avoid valgus or varus stress. There is no restriction in range of motion. A continuous passive motion elbow chair supports the patient in regaining elbow mobility.

RESULTS

Between 2015 and 2017, we treated 10 patients suffering from chronic coronoid defects with coronoid reconstruction. Eight of the patients were available for follow-up 86 weeks after surgery. The mean age was 41.4 years. In all patients, elbow range of motion and patient-related outcome measures were improved after surgery. Plain radiographs illustrated correct centering of the elbow joint. One patient had to undergo elbow arthroplasty and was excluded. Coronoid reconstruction with an autologous iliac crest bone graft restored humeroulnar joint congruency and improved satisfaction in patients suffering from chronic coronoid deficiency.

The inter-individual anatomical variation of the trochlear notch as a predisposition for simple elbow dislocation

PURPOSE

Besides the multi-layered capsule-ligamentous complex of the elbow joint the high bony congruence in the ulnohumeral joint contributes to elbow stability. Therefore, we assume that specific anatomical configurations of the trochlear notch predispose to dislocation. In case of ligamentous elbow dislocation both conservative and surgical treatment is possible without a clear treatment algorithm. Findings of constitutional bony configurations could help deciding for the best treatment option.

METHODS

In this retrospective matched-pair analysis we compared MRI imaging from patients sustaining a primary traumatic elbow dislocation (instability group) with patients suffering from chronic lateral epicondylitis (control group), treated between 2009 and 2019. Two independent observers measured different anatomical landmarks of the trochlear notch in a multiplanar reconstructed standardized sagittal trochlear plane (SSTP). Primarily, opening angle and relative depth of the trochlear notch were determined. After adjustment to the proximal ulnar rim in the SSTP, coronoid and olecranon angle, the articular angle as well as the ratio of the tip heights of the trochlear notch were measured.

RESULTS

We compared 34 patients in the instability group (age 48 ± 14 years, f/m 19/15) with 34 patients in the control group (age 47 ± 16 years, f/m 19/15). Instability group showed a significantly larger opening angle (94.1° ± 6.9° vs. 88.5° ± 6.9°, p = 0.0002), olecranon angle (60.9° ± 5.3° vs. 56.1° ± 5.1°, p < 0.0001) and articular angle (24.7° ± 6.4° vs. 22.3° ± 5.8°, p = 0.02) compared to the control group. Measuring the height from the coronoid (ch) and olecranon (oh) tip also revealed a significantly larger tip ratio (tr = ch/oh) in the instability group (2.7 ± 0.8 vs. 2.2 ± 0.5, p < 0.0001). The relative depth (61.0% ± 8.3% vs. 62.7% ± 6.0%, p = 0.21) of the trochlear notch as well as the coronoid angle (32.8° ± 4.5° vs. 31.7° ± 5.2°, p = 0.30) showed no significant difference in the instability group compared to the control group. The interrater reliability of all measurements was between 0.83 and 0.94.

CONCLUSION

MRI of patients with elbow dislocation show that there seems to be a bony anatomical predisposition. According to the results, it seems reasonable to include predisposing bony factors in the decision-making process when surgical stabilization and conservative treatment is possible. Further biomechanical studies should prove these assumptions to generate critical bony values helping surgeons with decision making.

LEVEL OF EVIDENCE

III.

Novel Radiographic Indexes for Elbow Stability Assessment: Part A-Cadaveric Validation

INTRODUCTION

Elbow bony stability relies primarily on the high anatomic congruency between the humeral trochlea and the ulnar greater sigmoid notch. No practical tools are available to distinguish different morphotypes of the proximal ulna and herewith predict elbow stability. The aim of this study was to assess inter-observer reproducibility, evaluate diagnostic performance and determine responsiveness to change after simulated coronoid process fracture for three novel elbow radiographic indexes.

METHODS

Ten fresh-frozen cadaver specimens of upper limbs from human donors were available for this study. Three primary indexes were defined, as well as two derived angles: Trochlear Depth Index (TDI); Posterior Coverage Index (PCI); Anterior Coverage Index (ACI); radiographic coverage angle (RCA); olecranon-diaphisary angle (ODA). Each index was first measured on standardized lateral radiographs and subsequently by direct measurement after open dissection. Finally, a type II coronoid fracture (Regan and Morrey classification) was created on each specimen and both radiographic and open measurements were repeated. All measurements were conducted by two orthopaedic surgeons and two dedicated musculoskeletal radiologists.

RESULTS

All three indexes showed good or moderate inter-observer reliability and moderate accuracy and precision when compared to the gold standard (open measurement). A significant change between the radiographic TDI and ACI before and after simulated coronoid fracture was observed [TDI: decrease from 0.45 ± 0.03 to 0.39 ± 0.08 (p = 0.035); ACI: decrease from 1.90 ± 0.17 to 1.58 ± 0.21 (p = 0.001)]. As expected, no significant changes were documented for the PCI. Based on these data, a predictive model was generated, able to identify coronoid fractures with a sensitivity of 80% and a specificity of 100%.

CONCLUSION

New, simple and easily reproducible radiological indexes to describe the congruency of the greater sigmoid notch have been proposed. TDI and ACI change significantly after a simulated coronoid fracture, indicating a good responsiveness of these parameters to a pathological condition. Furthermore, combining TDI and ACI in a regression model equation allowed to identify simulated fractures with high sensitivity and specificity. The newly proposed indexes are, therefore, promising tools to improve diagnostic accuracy of coronoid fractures and show potential to enhance perioperative diagnostic also in cases of elbow instability and stiffness.

LEVEL OF EVIDENCE

Basic science study.

CLINICAL RELEVANCE

The newly proposed indexes are promising tools to improve diagnostic accuracy of coronoid fractures as well as to enhance perioperative diagnostic for elbow instability and stiffness.

Novel Radiographic Indexes for Elbow Stability Assessment: Part B-Preliminary Clinical Study

INTRODUCTION

The coronoid process plays a key-role in preserving elbow stability. Currently, there are no radiographic indexes conceived to assess the intrinsic elbow stability and the joint congruency. The aim of this study is to present new radiological parameters, which will help assess the intrinsic stability of the ulnohumeral joint and to define normal values of these indexes in a normal, healthy population.

METHODS

Four independent observers (two orthopaedic surgeons and two radiologists) selected lateral view X-rays of subjects with no history of upper limb disease or surgery. The following radiographic indexes were defined: trochlear depth index (TDI); anterior coverage index (ACI); posterior coverage index (PCI); olecranon-coronoid angle (OCA); radiographic coverage angle (RCA). Inter-observer and intra-observer reproducibility were assessed for each index.

RESULTS

126 subjects were included. Standardized lateral elbow radiographs (62 left and 64 right elbows) were obtained and analysed. The mean TDI was 0.46 ± 0.06 (0.3-1.6), the mean ACI was 2.0 ± 0.2 (1.6-3.1) and the mean PCI was 1.3 ± 0.1 (1.0-1.9). The mean RCA was 179.6 ± 8.3° (normalized RCA: 49.9 ± 2.3%) and the mean OCA was 24.6 ± 3.7°. The indexes had a high-grade of inter-observer and intra-observer reliability for each of the four observers. Significantly higher values were found for males for TDI, ACI, PCI and RCA.

CONCLUSION

The novel radiological parameters described are simple, reliable and easily reproducible. These features make them a promising tool for radiographic evaluation both for orthopaedic surgeons and for radiologists in the emergency department setting or during outpatient services.

LEVEL OF EVIDENCE

Basic Science Study (Case Series).

CLINICAL RELEVANCE

The novel radiological parameters described are reliable, easily reproducible and become handy for orthopaedic surgeons as well as radiologists in daily clinical practice.

Elbow Fracture-Dislocations: Determining Treatment Strategies

Elbow dislocations represent common injuries. A quarter of these injuries involve at least 1 fracture. The sequel of elbow fracture-dislocations can be fraught with complications, including recurrent instability, posttraumatic arthritis, elbow contracture, and poor functional results. The 3 main patterns of injury are valgus posterolateral rotatory instability, varus posteromedial rotatory instability, and transolecranon fracture-dislocation. This article discusses each pattern individually, including the anatomy, the typical injury pattern, and treatment strategies. It also discusses common complications that can occur.

Functional Outcome of Surgically Treated Isolated Coronoid Fractures With Elbow Dislocation in Young and Active Patients

Coronoid fractures are less frequent injuries seen in around one-tenth of patients with elbow dislocation. Any injury to the coronoid process can be associated with elbow instability, in which injury to collateral ligaments co-exists, resulting in a loss of congruency of the elbow joint. However, there is a scarcity of evidence regarding patients' management with elbow dislocation and associated coronoid fractures. So, our aim is to assess the functional outcome of the elbow after operative fixation in patients with any type of coronoid fracture with associated elbow dislocation. A total of six patients with closed coronoid fracture of the elbow, with associated elbow dislocation, without any other associated trauma or previous surgery to the same limb, were included in our study. After closed reduction, patients with an incongruent reduction of the elbow joint were operated. The injured structures were repaired in an inside-out sequence: the coronoid fragment was first reduced by using a lasso-type suture. The larger fragments of the coronoid were fixed with either a screw or a plate when deemed necessary. Then, the lateral collateral ligament was repaired either using a suture anchor or transosseous (No. 2 Arthrex; Naples, Florida) sutures.

After repair, the elbow was examined for stability radiologically using the hanging arm test; a concentric reduction of the elbow in lateral view during this test indicates a stable elbow. All patients showed a good to excellent outcome on the Mayo elbow performance score (MEPS) at the final follow-up (three patients had an excellent score while three had a good score). At the final follow-up, mean elbow flexion was 124º, loss of extension was 10º in only one patient, mean supination was 80º, and mean pronation was 72º. Isolated fractures of the coronoid associated with elbow dislocation require appropriate evaluation and management. Closed reduction and immobilization alone in young and active patients may not be sufficient, especially in patients with incongruent ulnohumeral joint. Surgical fixation of the coronoid fragment and repair of the collateral ligament, whenever indicated, can provide good functional outcomes.

Prediction of the Size of the Fragment in Comminuted Coronoid Fracture Using the Contralateral Side: An Analysis of Similarity of Bilateral Ulnar Coronoid Morphology

OBJECTIVE

To evaluate the morphological similarity of bilateral coronoid process.

METHODS

A total of 128 sets of computed tomography images of bilateral coronoid process from patients between January 2015 and December 2016 were acquired for three-dimensional reconstruction to generate a coronoid process model. The patients were aged between 31.4 ± 9.3 years. The upper 40% of the coronoid process was trimmed as targeted fragment for morphological analysis. The height, length, width as well as the radius of the medial and lateral facet of the targeted fragment were compared in terms of laterality, age, and gender. To evaluate the similarity of the articular surface of the coronoid process, a local coordinate was created and coordinate transformation algorithm was developed to realign the bilateral coronoid process for the following matching. Then Delaunay triangulation was introduced for calculation of the area of the articular surface. After matching of articular surface of the upper 40% of bilateral coronoid process, the overlapping area of the articular surface was quantified to assess the similarity in morphology and compared in regard to age and gender.

RESULTS

In this study, the height of the target fragment was 12.40 ± 2.74 mm, which was 12.62 ± 2.06 mm for male patients and 12.13 ± 3.76 mm for female patients (t = 0.94, P = 0.35). The height of the target fragment was 12.79 ± 1.76 mm for patients >40 years and 13.23 ± 3.16 mm for patients <40 years (t = 1.11, P = 0.27). The height of the target fragment of left and right coronoid process was 12.26 ± 3.40 mm and 12.74 ± 2.79 mm (t = 1.15, P = 0.25). The length of the target fragment was 23.81 ± 2.67 mm, which was 23.86 ± 2.11 mm for male patients and 23.76 ± 2.85 mm for female patients (t = 0.23, P = 0.82). The length of the target fragment was 22.92 ± 1.96 mm for patients >40 years and 23.23 ± 2.14 mm for patients <40 years (t = 0.76, P = 0.45). The length of the target fragment of left and right coronoid process was 22.52 ± 2.89 mm and 21.66 ± 3.01 mm, respectively (t = 1.00, P = 0.32). The width of the target fragment was 23.12 ± 1.92 mm on average, which was 23.06 ± 1.54 mm for male patients and 23.19 ± 2.82 mm for female patients (t = 0.33, P = 0.74). The width of the target fragment was 24.82 ± 2.23 mm for patients >40 years and 23.46 ± 3.38 mm for patients <40 years (t = 1.56, P = 0.12). The width of target fragment of left and right coronoid process was 24.42 ± 2.22 mm and 24.47 ± 2.69 mm, respectively (t = 1.31, P = 0.19). The radius of medial facet was 6.44 ± 1.01 mm, which was 6.41 ± 1.39 mm for male patients and 6.47 ± 0.95 mm for female patients (t = 0.28, P = 0.78). The radius of medial facet was 6.82 ± 1.28 mm for patients >40 years and 6.46 ± 0.94 mm for patients <40 years (t = 1.31, P = 0.19). The radius of medial facet of left and right coronoid process was 6.43 ± 1.24 mm and 6.64 ± 1.34 mm (t = 1.60, P = 0.11). The radius of lateral facet was 11.84 ± 3.71 mm, which was 11.61 ± 4.24 mm for male patients and 12.11 ± 3.09 mm for female patients (t = 0.74, P = 0.46). The radius of medial facet was 11.82 ± 3.28 mm for patients >40 years and 12.46 ± 3.94 mm for patients <40 years (t = 1.02, P = 0.31). The radius of lateral facet of left and right coronoid process was 11.97 ± 5.31 mm and 10.29 ± 3.29 mm, respectively (t = 1.70, P = 0.09). The covering percentage of the articular surface of the upper 40% of bilateral coronoid process was 87% ± 12% with the covering percentage as 85.3% ± 14.2% for male patients and 90.0% ± 11.2% for female patients (t = 0.75, P = 0.41). The covering percentage was 88.2% ± 11.7% for patients >40 years and it was 87.4% ± 13.2% for patients <40 years (t = 0.98, P = 0.33).

CONCLUSIONS

The present study suggested that bilateral coronoid process shares high similarity in terms of 3D structure and articular surface morphology, which suggested that the osseous architecture of the coronoid process with comminuted fracture could be predicted by the morphological information of the contralateral side.

Radial head fractures

The shape and size of the radial head is highly variable but correlates to the contralateral side. The radial head is a secondary stabilizer to valgus stress and provides lateral stability. The modified Mason-Hotchkiss classification is the most commonly used and describes three types, depending on the number of fragments and their displacement. Type 1 fractures are typically treated conservatively. Surgical reduction and fixation are recommended for type 2 fractures, if there is a mechanical block to motion. This can be done arthroscopically or open. Controversy exists for two-part fractures with >2 mm and <5 mm displacement, without a mechanical bloc as good results have been published with conservative treatment. Type 3 fractures are often treated with radial head replacement. Although radial head resection is also an option as long-term results have been shown to be favourable. Radial head arthroplasty is recommended in type 3 fractures with ligamentous injury or proximal ulna fractures. Failure of primary radial head replacement may be due to several factors. Identification of the cause of failure is essential. Failed radial head arthroplasty can be treated by implant removal alone, interposition arthroplasty, revision radial head replacement either as a single stage or two-stage procedure.

Most coronoid fractures and fracture-dislocations with no radial head involvement can be treated nonsurgically with elbow immobilization

HYPOTHESIS

Conservative treatment of isolated coronoid fractures and fracture-dislocations focused on soft-tissue healing can provide good clinical results in the majority of patients. Our aims were (1) to evaluate the outcome of a conservative treatment protocol designed for isolated coronoid fractures with or without associated elbow dislocations (ICFs) and (2) to characterize the fractures with a dedicated image analysis protocol.

METHODS

Of 38 consecutive patients sustaining acute ICFs, 28 were treated nonsurgically after meeting specific inclusion criteria, prospectively followed up, and clinically evaluated at least 1 year after sustaining their injuries. All cases underwent elbow computed tomography scans with tri-plane and 3-dimensional reconstructions according to a specific protocol referenced to the proximal ulna.

RESULTS

The study included 15 male and 13 female patients, with a mean follow-up period of 32 ± 14 months (range, 12-61 months). An associated dislocation was presented in 8 (29%). Mean extension and flexion were 2° ± 8° (range, -10° to 30°) and 139° ± 11° (range, 110°-155°), respectively. Mean pronation and supination were 74° ± 3° (range, 60°-75°) and 83° ± 9° (range, 40°-85°), respectively. Of the patients, 78% rated their elbow as being normal or nearly normal. The mean Mayo Elbow Performance Score was 95 ± 9 (range, 70-100). The mean Disabilities of the Arm, Shoulder and Hand score was 7 ± 13 (range, 0-57). The mean coronoid fracture height was 5.7 ± 1.2 mm (range, 3.7-7.9 mm). The mean percentage of coronoid height fractured was 33% ± 6% (range, 23%-43%). Mean fracture displacement was 2.7 ± 2 mm (range, 1-9 mm). Of the fractures, 23 (82%) were located at the anteromedial coronoid.

CONCLUSION

An ICF with a perfectly reduced ulnohumeral joint, a competent sublime tubercle, and a fractured coronoid height up to 50% can be treated without surgery with excellent or good results in more than 90% of cases regardless of the location of the fracture in the coronoid or the type of soft tissue-associated disruptions.

The Acutely Injured Elbow

The acutely injured elbow can present as a diagnostic challenge, encompassing a spectrum of conditions that involve the various osseous and soft tissue structures of this complex joint. Imaging plays a vital role in the management of these patients by providing an accurate interpretation of the underlying trauma sustained, which can have important implications on the preservation of joint function and stability. This article examines the mechanisms, patterns, classifications, and imaging findings of acute elbow injuries, providing key concepts for the radiologist in the interpretation of these injuries.

The shape match of the olecranon tip for reconstruction of the coronoid process: influence of side and osteotomy angle

BACKGROUND

The integrity of the coronoid process is critical to maintaining elbow stability. Unreconstructible fractures and chronic coronoid deficiency are challenging clinical problems with no clear solution. The purposes of this study were to investigate the shape match of the ipsilateral and contralateral olecranon tips as graft options and to determine the influence of the osteotomy angle on fitment.

METHODS

Nineteen paired cadaveric elbow joints were investigated by 3-dimensional digital analysis of computed tomography DICOM (Digital Imaging and Communications in Medicine) data. After construction of an ulnar coordinate system, the ipsilateral and contralateral olecranon tips were digitally harvested at 10°, 20°, 30°, 40°, 50°, and 60° osteotomy angles. In an overlay analysis, we compared the shape match of the ipsilateral and contralateral grafts and the different angles.

RESULTS

The ipsilateral grafts showed an average mismatch of 1.8 mm (standard deviation, 1.38 mm), whereas the contralateral grafts had a significantly lower (P < .001) mean mismatch of 1.3 mm (standard deviation, 0.95 mm). The 50° osteotomy plane showed the best shape match in comparison with the native coronoid-in both the ipsilateral and contralateral grafts. Evaluation of the intraclass correlation coefficient was calculated at r = 0.944, showing high repeatability of the measurements.

CONCLUSIONS

The contralateral olecranon tip graft showed significantly better shape matching to the native coronoid than the ipsilateral olecranon graft. Specifically, the contralateral graft more closely matched the biomechanically critical anteromedial coronoid facet. Finally, both the contralateral and ipsilateral olecranon grafts had better shape matching with the native coronoid when osteotomy was performed at higher angles, specifically 50°.

Posteromedial rotatory incongruity of the elbow: a computational kinematics study

BACKGROUND

Our objective was to analyze the effect of different anteromedial coronoid fracture patterns with different combinations of ligamentous repairs. We hypothesized that smaller fractures would be sufficiently treated with ligamentous repair alone but that larger fragments would require a combination of ligament and bony repair versus reconstruction.

METHODS

Two multibody models were created from cadaveric specimens in the ADAMS program. Four different conditions were simulated: (1) no fracture, (2) O'Driscoll anteromedial subtype I (2.5-mm) fracture, (3) subtype II 2.5-mm fracture, and (4) subtype II 5-mm fracture. In each of these conditions, 3 ligament repairs were studied: lateral ulnar collateral ligament (LUCL), posterior bundle of the medial collateral ligament (pMCL), and both LUCL and pMCL. For each condition, kinematics and articular contact areas were calculated.

RESULTS

LUCL repair alone increases whereas pMCL repair decreases internal rotation of the ulna relative to all tested posteromedial rotatory instability conditions; their rotational effects are summative when both ligaments are repaired. With a subtype I fracture and both pMCL and LUCL injuries, repairing the LUCL alone corrects angulation whereas rotational stability is satisfactory through the arc from 0° to 90°. In a subtype II 2.5-mm fracture, isolated repair of the LUCL or pMCL is not capable of restoring rotation or angulation. For a subtype II 5-mm fracture, no combination of ligamentous repairs could restore rotation or angulation.

CONCLUSIONS

This study suggests that LUCL repair alone is sufficient to restore kinematics for small subtype I fractures for an arc avoiding deep flexion; whereas nearly normal kinematics throughout the arc of motion can be achieved if the pMCL is also repaired. Larger anteromedial coronoid fractures should ideally have fragments fixed in addition to ligament repairs.

Anteromedial fractures of the ulnar coronoid process: correlation between surgical outcomes and radiographic findings

BACKGROUND

This study aimed to report the radiographic findings and surgical outcomes of anteromedial facet (AMF) fracture of the ulnar coronoid process and to suggest an optimal approach.

METHODS

In this retrospective study, 20 consecutive patients with unilateral AMF fracture of coronoid process were surgically treated and divided into two groups without (group A) and with (group B) additional proximal ulnar fractures in equal case number. Time from injury to surgery averaged 4.38 ± 2.56 weeks. Mayo Elbow Performance Score (MEPS) and Shortened Disability of the Arm and Shoulder and Hand (quickDASH) score were used for functional evaluation. Cohen kappa coefficient (kappa) analysis was used to determine interobserver reliability on a radiographic reading.

RESULTS

All cases had a mean follow-up of 2.3 years. MEPS at 2 years averaged 87.75 ± 12.51; quickDASH, 7.05 ± 6.19. A significantly higher MEPS was found in subtype 3 than in subtype 2 (p = 0.036) and in group B than in group A (p = 0.020). Significantly lower quickDASH cores were found in group B than in group A (p = 0.011). Kappa analysis showed moderate agreement in the O'Driscoll classification (kappa = 0.56) and substantial agreement in categorization of the additional proximal ulnar fractures (kappa = 0.76).

CONCLUSIONS

Additional proximal ulnar lesions were considered an integral part of varus posteromedial rotatory instability and required further categorization in the management of AMF fractures. Significantly better functional outcomes were achieved when those lesions were fully addressed.

Osteochondral coronoid allograft in chronic coronoid process bone loss reconstruction: an original technique with encouraging clinical and radiological outcomes at a mid-term follow-up

Objectives

Ulnar coronoid apophysis is a primary stabiliser of the elbow; a relatively small amount of bone loss, quantifiable in 40%, could be sufficient to make an elbow incongruent. If coronoid fixation is not possible, the only way of achieving a stable elbow is to reconstruct it. This case series describes the senior author’s original surgical technique in reconstructing the coronoid with a fresh-frozen osteochondral coronoid allograft, reporting a mid-term follow-up (average of 55.5 months, minimum of 26 months) of four patients (described one by one) with subjective and objective outcomes.

Methods

The senior author operated on four patients with his original surgical technique, fully explained in the text. The mean follow-up at the time is 55.5 months (up to 10 years in one case). Preoperatively and postoperatively, the patients were asked to answer three types of validated scales: Visual Analogue Scale (VAS), Quick-Disabilities of the Arm Shoulder and Hand (Quick-DASH) and Mayo Elbow Performance Index (MEPI). All patients underwent preoperative X-rays and CT scans. Afterwards, they were asked to have further X-rays and a dual- energy CT scan in the last-follow up.

Results

Three patients achieved 100 points on the MEPI scale. Three patients achieved full range of motion (ROM), while the fourth one easily achieved functional ROM. The VAS score mean improvement was 50%, and two patients were completely pain-free; the Quick-DASH average improvement score was 56.82 points.

Conclusions

This case series presents an original technique using a coronoid allograft. Three of four patients achieved full ROM, and two were pain-free at follow up. Everyone resumed previous levels at work and in sports. The good outcomes suggest that this procedure seems to be safe and does not necessarily require autologous structures. The lack of registered cases of graft reabsorption may encourage the use of an osteochondral coronoid allograft.

Level of evidence

Level IV.

[Research progress of posteromedial rotatory instability of the elbow]

Objective

To summarize the research progress in posteromedial rotatory instability (PMRI) of the elbow joint.

Methods

The recent researches about the management of PMRI of the elbow joint from the aspects of pathological anatomy, biomechanics, diagnosis, and therapy were analyzed and summarized.

Results

The most important factors related to PMRI of the elbow joint are lateral collateral ligament complex (LCLC) lesion, posterior bundle of the medial collateral ligament complex (MCLC) lesion, and anteromedial coronoid fracture. Clinical physical examination include varus and valgus stress test of the elbow joint. X-ray examination, computed tomography, particularly three-dimensional reconstruction, are particularly useful to diagnose the fracture. Also MRI, arthroscopy, and dynamic ultrasound can assistantly evaluate the affiliated injury of the parenchyma. It is important to repair and reconstruct LCLC and MCLC and fix coronoid process fracture for recovering stability of the elbow joint. There are such ways to repair ligament injury as in situ repairation and functional reconstruction, which include direct suturation, borehole repairation, wire anchor repairation, and transplantation repairation etc. The methods for fixation of coronal fracture include screw fixation, plate fixation, unabsorbable suture fixation, and arthroscopy technology.

Conclusion

It is crucial that recovering the stability of the elbow joint and early functional exercise for the treatment of PMRI. Individual treatment is favorable to protect soft tissue, reduce surgical complications, and improve the functional recovery and the quality of life.

Articular Contact Area and Pressure in Posteromedial Rotatory Instability of the Elbow

BACKGROUND

Joint incongruity in posteromedial rotatory instability (PMRI) has been theorized to determine early articular degenerative changes. Our hypothesis was that the articular contact area and contact pressure differ significantly between an intact elbow and an elbow affected by PMRI.

METHODS

Seven cadaveric elbows were tested under gravity varus stress using a custom-made machine designed to simulate muscle loads and allow passive elbow flexion (0° to 90°). The mean contact area and contact pressure data were collected and processed using the Tekscan sensor and software. After testing the intact specimen (intact elbow), a PMRI injury was simulated (PMRI elbow) and the specimen was tested again.

RESULTS

The PMRI elbows were characterized by initial joint subluxation and significantly elevated articular contact pressure. Both worsened, corresponding with a reduction in contact area, as the elbow was flexed from 0° until the joint subluxation and incongruity spontaneously reduced (at a mean [and standard error] of 60° ± 5° of flexion), at which point the mean contact pressure decreased from 870 ± 50 kPa (pre-reduction) to 440 ± 40 kPa (post-reduction) (p < 0.001) and the mean contact area increased from 80 ± 8 mm to 150 ± 58 mm (p < 0.001). This reduction of the subluxation was also followed by a shift of the contact area from the coronoid fracture edge toward the lower portion of the coronoid. At the flexion angle at which the PMRI elbows reduced, both the contact area and the contact pressure of the intact elbows differed significantly from those of the PMRI elbows, both before and after the elbow reduction (p < 0.001).

CONCLUSIONS

The reduction in contact area and increased contact pressures due to joint subluxation and incongruity could explain the progressive arthritis seen in some elbows affected by PMRI.

CLINICAL RELEVANCE

This biomechanical study suggests that the early degenerative changes associated with PMRI reported in the literature could be subsequent to joint incongruity and an increase in contact pressure between the coronoid fracture surface and the trochlea.

A novel anterior approach for the fixation of ulnar coronoid process fractures

BACKGROUND

There is no universally accepted approach to the elbow for the fixation of coronoid process fractures. This study aims to introduce a novel anterior surgical approach for the fixation of the ulnar coronoid fracture, with minimal surgical dissection damage and excellent visualization for reduction and internal fixation.

HYPOTHESIS

The anterior approach can facilitate satisfactory outcomes for coronoid process fractures.

MATERIAL AND METHODS

From February 2010 to July 2014, 12 patients (8 males and 4 females; range 14-62years; mean age 31years) with a closed fracture of the coronoid process of the ulna were included in this study. According to Adams classification, we included 5 type II, 3 type III, 3 type IV AM, and 1 type IV AL. The fractures were treated operatively via an anterior approach between nerves and blood vessels. The anatomical reduction and fixation with cannulated screws or a mini plate was easily performed. One elbow showed significant joint instability, necessitating, another incision to repair the lateral collateral ligament, and a subsequent operation with a hinged external fixator was required. The remaining patients received a splint for 2 weeks followed by functional exercises.

RESULTS

Mean follow-up was 21 months (13-36). Fracture union was achieved in each patient. The arc of elbow flexion and extension were (135±15)°, and forearm pronation/supination were restored to (165±15)°. When compared with the normal side, there was no significant difference in the functional outcome (P>0.05). According to Morrey' scale, the functional recovery of the injured arms was assessed as excellent in eleven patients and good in one. Mild heterotopic ossification was found in one case, which had not impaired the elbow function. No other complications were noted.

CONCLUSIONS

The anterior approach has the benefits of simplicity, safety, minimal invasion, excellent exposure, and satisfactory prognosis for coronoid process fractures.

LEVEL OF EVIDENCE

Prospective study, Level IV.

Simple elbow dislocation

The elbow is the second most commonly dislocated major joint in adults. Good long-term outcomes have been reported after non-operative management; however, a small proportion (<10%) of patients have a poor outcome and some do require surgical intervention. A review of the anatomy, pathoanatomy, management and outcomes of simple elbow dislocations is presented. Emphasis is placed on emerging concepts regarding the soft tissue injury, the stabilising structures that are injured, the sequence and mechanism of injury and the relationship to elbow stability. The benefits of nonsurgical and surgical management are discussed and a treatment algorithm based on the pathoanatomy is proposed.

Complex instability of the elbow

Injuries to the elbow are commonly encountered in orthopaedic practice. They range from low energy, simple isolated fractures, to high energy complex fracture dislocations with severe ligamentous disruption. Recognising the precise pattern of injury is critical in restoring elbow function and preventing chronic instability, pain and weakness. This article discusses the important osseous and ligamentous stabilisers of the elbow joint and provides management protocols for the common patterns of complex injury encountered by the practising surgeon.

Arthroscopic Management of Elbow Fractures

Several types of elbow fractures are amenable to arthroscopic or arthroscopic-assisted fracture fixation, including fractures of the coronoid, radial head, lateral condyle, and capitellum. Other posttraumatic conditions may be treated arthroscopically, such as arthrofibrosis or delayed radial head excision. Arthroscopy can be used for assessment of stability or intra-articular fracture displacement. The safest portals are the midlateral (soft spot portal), proximal anteromedial, and proximal anterolateral. Although circumstances may vary according to the injury pattern, a proximal anteromedial portal is usually established first. Arthroscopy enables a less invasive surgical exposure that facilitates visualization of the fracture fragments in select scenarios.

Varus Posteromedial Instability

Varus posteromedial instability of the elbow is a result of traumatic injury to the medial facet of the coronoid and usually the lateral collateral ligament. Treatment of these fractures is usually surgical; poor outcomes have been described with nonoperative treatment. Surgical management consists of coronoid fracture fixation with plates, screws, or sutures and radial collateral ligament repair. Outcomes of these injuries are mixed, but most series report fair to good objective scores. The purpose of this article is to describe the pathophysiology of varus posteromedial instability, discuss the management of this injury, and report the outcomes of treatment.

A novel approach for coronoid fractures

The coronoid process serves as an important constraint that provides ulnohumeral joint stability. We describe a novel approach to coronoid fractures that minimizes surgical dissection, without compromising fracture visualization. We present the case of a 65-year-old woman who sustained an anteromedial facet fracture of the coronoid process. The elbow demonstrated intractable posteromedial instability and the inability to maintain reduction even up to 90 degrees. This report describes a surgical approach to the coronoid process that minimizes extensive soft tissue dissection. It is a variation of the previously described approach by Taylor and Scham, although it can achieve a similar exposure without elevation of the entirety of the flexor-pronator mass. Our approach involves a limited skin incision, followed by elevation of enough of the flexor-pronator mass such that adequate visualization of the posterior medial collateral ligament (which was repaired), anteromedial facet, and the fractured fragment of coronoid were achieved. Moreover, this approach enables the course of the ulnar nerve to remain unaltered.

Single-staged treatment using a standardized protocol results in functional motion in the majority of patients with a terrible triad elbow injury

BACKGROUND

Terrible triad injuries of the elbow, defined as elbow dislocation with associated fractures to the radial head and coronoid, are associated with stiffness, pain, and loss of motion. Studies to date have consisted of small sample sizes and used heterogeneous surgical techniques, which render comparisons difficult and unreliable.

QUESTIONS/PURPOSES

In a group of patients treated under a standard surgical protocol, we sought to determine the early dislocation rate, the range of motion in those not undergoing secondary procedures, the frequency and types of secondary surgical interventions required, the difference in motion between those undergoing secondary surgery and those who did not, and the frequency of heterotopic ossification and patient-reported stiffness.

METHODS

Patients underwent a surgical protocol that involved fixing the coronoid, fixing the radial head if possible, otherwise performing radial head arthroplasty, and repairing the lateral ligamentous structures. Patients were excluded if ipsilateral upper extremity fractures from the humerus to the distal forearm were present. Fifty-two patients had a minimum followup of 6 weeks and were included for the early dislocation rate, and 34 of these (65%) had a minimum of 6 months followup and were included for the rest of the data. Eighteen of the 52 (35%) were considered lost to followup because they were seen for less than 6 months postsurgically and were excluded from further analysis. Chart review was performed to determine the presence of early dislocation within the first 6 weeks after surgery, range of motion in patients not requiring a secondary procedure, the frequency and types of secondary procedures required, the range of motion before and after a secondary procedure if it was required, and postoperative stiffness. Postoperative radiographs were analyzed to determine the presence and severity of heterotopic ossification.

RESULTS

One of 52 patients sustained a dislocation within the first weeks of surgery (1.9%). Those not undergoing a secondary procedure were able to achieve a flexion arc of 110° and a supination-pronation arc of 148°. Nine of 34 patients (26%) underwent a secondary surgical procedure with stiffness, heterotopic ossification, and ulnar neuropathy being the most common surgical indications. Before secondary surgical procedures, patients had a flexion arc of 57° and a supination-pronation arc of 55°, which was less than those only requiring primary surgery alone (p < 0.001). After secondary surgery, patients were able to achieve a flexion arc of 96° and a supination-pronation arc of 124°, which was not different from those who did not undergo reoperation (p = 0.09 and p = 0.08, respectively). Twenty-eight of 34 patients demonstrated evidence of heterotopic ossification on radiographs, whereas 20 patients, including all nine undergoing secondary procedures, reported stiffness at the elbow.

CONCLUSIONS

Using a standardized surgical protocol, a low early dislocation rate was observed, although stiffness remains a challenge. Many patients who initially do not attain functional range of motion can usually attain this after secondary procedures aimed at removing the heterotopic ossification.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See guidelines for authors for a complete description of levels of evidence.

Biomechanical testing of a novel osteosynthesis plate for the ulnar coronoid process

BACKGROUND

The present study aimed to biomechanically evaluate a novel locking plate intended for osteosynthesis of coronoid fracture compared to mini L-plates and cannulated screws.

METHODS

Biomechanical tests were performed on a fracture model in synthetic bones. Three groups, each with eight implant-bone-constructs, were analyzed in quasi-static and dynamic tests. Finally, samples were tested destructively for maximum strength.

RESULTS

The mean (SD) highest stiffness was measured for the novel plate [693 (18) N/mm], followed by the mini L-plate [646 (37) N/mm] and the cannulated screws [249 (113) N/mm]. During the cycling testing of the novel plate and the mini L-plate, no failures occurred, although three of the eight samples of cannulated screws failed during the test. The mean (SD) maximum strength during the destructive testing was 1333 (234) N for the novel plate, 1338 (227) N for the mini-L-plate and 459 (56) N for the cannulated screws. No statistical differences were found during the destructive testing between the two plates (p = 0.999), although statistical differences were found between both plates and the cannulated screws (p = 0.000 each).

CONCLUSIONS

Osteosynthesis of the coronoid process using the novel plate is mechanically similar to the mini L-plate. Both plates were superior to osteosynthesis with cannulated screws.

Reconstruction of the coronoid process using the tip of the ipsilateral olecranon

BACKGROUND

Autograft reconstruction of the coronoid using the tip of the olecranon has been described as a treatment option for comminuted coronoid fractures or coronoid nonunions that are not repairable. The purpose of this in vitro biomechanical study of the coronoid-deficient elbow was to determine whether coronoid reconstruction using the tip of the ipsilateral olecranon would restore elbow kinematics.

METHODS

An elbow motion simulator was used to perform active and passive extension of six cadaveric arms in the horizontal, valgus, varus, and vertical orientations. Elbow kinematics were quantified with use of the screw displacement axis of the ulna with respect to the humerus. Testing was performed with an intact coronoid, a 40% coronoid deficiency, and a coronoid reconstruction using the tip of the ipsilateral olecranon.

RESULTS

Creation of a 40% coronoid deficiency resulted in significant changes (range, 3.6° to 10.9°) in the angular deviations of the screw displacement axis relative to the intact state during simulated active and passive extension in the varus orientation with the forearm in pronation and in supination (p < 0.05). Reconstruction of the coronoid using the ipsilateral olecranon tip restored the angular deviations to those in the intact state (p > 0.05) with the arm in all orientations except valgus, in which there was a small but significant difference (0.4° ± 0.2°, p = 0.04) during passive motion with forearm supination.

CONCLUSIONS

Reconstruction of the coronoid using the tip of the ipsilateral olecranon was an effective method for restoring normal kinematics over a range of elbow motion from 20° to 120° in a cadaveric model of an elbow with a 40% coronoid deficiency. This reconstruction technique may prove beneficial for patients with elbow instability due to coronoid deficiency.

The effect of a coronoid prosthesis on restoring stability to the coronoid-deficient elbow: a biomechanical study

PURPOSE

The coronoid process has been recognized as a critical component in maintaining elbow stability. In the case of comminuted coronoid fractures, where repair is not possible or has failed, a prosthesis may be beneficial in restoring the osseous integrity of the elbow joint. The hypothesis of this in vitro biomechanical study was that a coronoid prosthesis would restore stability to the coronoid-deficient elbow.

METHODS

An anatomically shaped metallic coronoid prosthesis was designed and developed based on computed tomography-derived measurements and optimized to account for average cartilage thickness. Elbow kinematics and stability were determined for 8 cadaveric arms in active and passive elbow flexion in the varus, valgus, horizontal, and vertical positions using an elbow motion simulator. Varus-valgus angulation and internal-external rotation of the ulna relative to the humerus were quantified in the intact state, after collateral ligament sectioning and repair (control state), after a simulated 40% transverse coronoid fracture, and after implantation of the coronoid prosthesis.

RESULTS

Internal rotation of the ulna increased with a 40% coronoid fracture in the horizontal and varus positions. Increases in varus angulation after coronoid fracture were also observed in the horizontal and varus positions, during active and passive flexion, respectively. Following implantation of the coronoid prosthesis, elbow kinematics were restored similar to control levels in all elbow positions.

CONCLUSIONS

Our findings support our hypothesis that an anatomically shaped coronoid prosthesis would be effective in restoring stability to the coronoid-deficient elbow.

CLINICAL RELEVANCE

This study provides evidence that the use of an anatomical implant restores stability to the coronoid-deficient elbow and rationale for further study and development of this method. For comminuted coronoid fractures, where repair is not possible or has failed, our research indicates that a prosthesis may be a feasible treatment option.

Surgical reconstruction of comminuted coronoid fracture in terrible triad injury of the elbow

The terrible triad injury of the elbow is the combination of an elbow dislocation, a radial head fracture and a coronoid process fracture. In this study, we explored the outcome of a modified protocol for terrible triad injury of the elbow in a consecutive series of 14 patients, with a focus on reconstruction of comminuted coronoid fractures. Fourteen patients with terrible triad injuries of the elbow were retrospectively reviewed at a mean follow-up of 23 months (range, 15-30 months) and were clinically and radiographically evaluated. For comminuted coronoid fractures, autografting with resected radial head fragment or ilium fragment with cartilage surface and transosseous suture with non-absorbable suture were performed. Internal fixation of the radial head was performed in six cases and arthroplasty in five. The collateral ligaments were repaired. Mean flexion at last follow-up was 125°, ranging from 100° to 135°. Mean extension loss was 13°, ranging from 0° to 38°. Mean pronation was 70° and mean supination was 66°. No patient experienced dislocation of the radial head prosthesis. The mean Mayo Elbow Performance Score (MEPS) was 87 (range, 75-100), with six excellent cases and eight good cases. According to our intraoperative examination, no patient demonstrated unacceptable residual instability in extension following restoration of all of the osseous and ligamentous lesions. In conclusion, our protocol can achieve stable reconstruction of the coronoid process, which promotes the functional outcome of surgical treatment on terrible triad injuries of the elbow.

Reconstruction of the coronoid using an extended prosthesis: an in vitro biomechanical study

BACKGROUND

When repair of comminuted coronoid fractures is not possible, prosthetic replacement may restore elbow stability. The purpose of this biomechanical study was to determine whether a coronoid implant with an extended tip would improve elbow stability compared with an anatomic prosthesis in the setting of collateral ligament insufficiency.

MATERIALS AND METHODS

Passive elbow extension was performed in 7 cadaveric arms in the varus and valgus positions and active and passive extension in the horizontal position by use of an elbow motion simulator. Varus-valgus laxity of the ulna relative to the humerus was quantified with a tracking system with a native coronoid, a 40% coronoid deficiency, an anatomic prosthesis, and an extended prosthesis, with the collateral ligaments sectioned and repaired.

RESULTS

Laxity significantly increased after a 40% coronoid deficiency with both repaired and sectioned collateral ligaments (P ≤ .01). With the ligaments repaired, there was no significant difference in laxity between the native coronoid, the anatomic implant, or the extended implant. Ligament sectioning alone produced severe instability, with a mean laxity of 42.75° ± 11.54° (P < .01). With insufficient ligaments, the anatomic prosthesis produced no change in laxity compared with the native coronoid, whereas the extended implant significantly reduced laxity by 21.56° ± 17.70° (P = .02).

CONCLUSIONS

An anatomic coronoid implant with ligament repair restores stability to the coronoid-deficient elbow to intact levels. In the setting of ligament insufficiency, an extended implant improves stability relative to an anatomic implant, but the elbow remains significantly less stable than an intact elbow. Studies are needed to evaluate the feasibility of these designs.

Fractures of the coronoid: morphology based upon computer tomography scanning

HYPOTHESIS/BACKGROUND

Coronoid fractures have traditionally been described by the Regan-Morrey classification system, based upon lateral plain film radiographs. However, use of computer tomography (CT) scans to determine fracture morphology, define associated injuries, and make treatment plans is now commonplace. In addition, it is increasingly recognized that classification systems based upon plain film imaging studies may not be adequate to describe complex fracture patterns. The purpose of the present investigation was to review CT scans obtained for elbow trauma to describe coronoid fracture morphology and determine inter- and intra-observer reliability.

METHODS

CT scans performed for elbow trauma over a 2-year period were examined to identify coronoid fractures, and recurring patterns were sought. After patterns were identified, the scans were reviewed by 3 observers to determine inter- and intra-observer reliability.

RESULTS

Of 373 CT scans, 52 identified coronoid fractures were appropriate for review. Five common patterns were identified, including a tip type, mid-transverse type, basal type, anteromedial oblique fractures, and an anterolateral oblique type fracture that has not been well described previously. Inter- and intra-observer reliability ranged from good to very good in this series.

DISCUSSION/CONCLUSION

In this series, we describe anatomic patterns by which coronoid fractures break. Five common patterns were noted: a "tip" type fracture seen in 29% of the cases; a "mid-transverse" type fracture (24%); a "basal" type fracture (23); and 2 "oblique" type fracture patterns (24%), including an "anteromedial" type fracture (17%) and an "anterolateral" type (7%). There was a high rate of intra- and inter-observer reliability between and within 3 observers.

Radial head replacement with unipolar and bipolar SBi system: a clinical and radiographic analysis after a 2-year mean follow-up

Radial head prosthetic replacement is indicated in case of comminuted fracture not amenable to internal fixation, especially when the radial head fracture is part of a pattern of lesions configuring a complex instability of the elbow. Thirty-one SBi radial head prostheses were implanted in 30 patients (one bilateral simultaneous fracture) over a 2 years period. In 10 patients, the mean time from trauma to surgical treatment was 2.4 days, while the remaining 20 patients were treated as "second opinion" cases presenting with elbow stiffness or instability after an average of 19 days from trauma. The implants were monopolar in 12 cases and bipolar in 19. The clinical results were evaluated through the Mayo Elbow performance scoring system. At an average follow-up of 2 years (range 13-36 months), the mean MEPS was 90 points (range 65-100). At late radiographic analysis, radiolucent lines around the stem were found in 11 of the 31 cases. Heterotopic ossifications were found in 14 cases. Bone resorption was observed in 9 cases. Two of the 31 prostheses were removed after 16 and 20 months, in one case to correct stiffness in pronation/supination, in the other one for asymptomatic aseptic mobilization. These short-term results are satisfactory, especially when considering that they were obtained in complex elbow lesions treated in many cases at a delayed stage. Our preference over time went more and more to bipolar implants, but from a comparison of the results we could find no evidence of a superiority of bipolar or monopolar implants. The evolution of these prostheses needs to be evaluated with further studies to assess mid-term and long-term follow-up results.

Surgical treatment of "terrible triad of the elbow": technique and outcome

OBJECTIVE

To describe the authors' surgical technique and to evaluate the final functional outcome of surgical treatment of the "terrible triad of the elbow".

METHODS

Eight patients identified with "terrible triad" injury patterns, including posterior elbow dislocation, radial head fracture and coronoid fracture, were available for a minimum of 11 months follow-up. Evaluation of functional outcome was based on Mayo elbow performance, Broberg-Morrey scores, and the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire. Complications were also recorded.

RESULTS

Five elbows redislocated while in a splint after manipulative reduction. Three had residual subluxation after operative treatment. The final mean extent of forearm movement was as follows: 21° of extension deficit (range, 5° to 45°), 126° of flexion (range, 110° to 140°), 75° of supination (range, 45° to 90°), and 71° of pronation (range, 30° to 90°). The mean Mayo, Broberg-Morrey, and DASH scores were 78.0 ± 13.4, 76.0 ± 14.0, and 28.0 ± 24.7, respectively.

CONCLUSIONS

When an elbow joint is affected by the terrible triad, it is very unstable and prone to numerous complications. With operative treatment, the surgeon should attempt to perform internal fixation of the coronoid fracture, to regain normal radiocapitellar contact (either by preserving the radial head with open reduction and internal fixation (ORIF) or by replacing it with a prosthesis), and to repair the lateral collateral ligament (LCL). Thus early functional recovery and a successful final functional outcome can be achieved.

The contribution of the coronoid and radial head to the stability of the elbow

We undertook this study to determine the minimum amount of coronoid necessary to stabilise an otherwise intact elbow joint. Regan-Morrey types II and III, plus medial and lateral oblique coronoid fractures, collectively termed type IV fractures, were simulated in nine fresh cadavers. An electromagnetic tracking system defined the three-dimensional stability of the ulna relative to the humerus. The coronoid surface area accounts for 59% of the anterior articulation. Alteration in valgus, internal and external rotation occurred only with a type III coronoid fracture, accounting for 68% of the coronoid and 40% of the entire articular surface. A type II fracture removed 42% of the coronoid articulation and 25% of the entire articular surface but was associated with valgus and external rotational changes only when the radial head was removed, thereby removing 67% of the articular surface. We conclude that all type III fractures, as defined here, are unstable, even with intact ligaments and a radial head. However, a type II deficiency is stable unless the radial head is removed. Our study suggests that isolated medial-oblique or lateral-oblique fractures, and even a type II fracture with intact ligaments and a functional radial head, can be clinically stable, which is consistent with clinical observation.

Stability of the elbow joint: relevant anatomy and clinical implications of in vitro biomechanical studies

The aim of this literature review is to describe the clinical anatomy of the elbow joint based on information from in vitro biomechanical studies. The clinical consequences of this literature review are described and recommendations are given for the treatment of elbow joint dislocation.

The PubMed and EMBASE electronic databases and the Cochrane Central Register of Controlled Trials were searched. Studies were eligible for inclusion if they included observations of the anatomy and biomechanics of the elbow joint in human anatomic specimens.

Numerous studies of the kinematics, kinesiology and anatomy of the elbow joint in human anatomic specimens yielded important and interesting implications for trauma and orthopaedic surgeons.

The comparative stability of screw versus plate versus screw and plate coronoid fixation

PURPOSE

To compare the biomechanical characteristics of screw versus plate versus both screw and plate fixation for large, type 3 O'Driscoll coronoid fractures.

METHODS

Synthetic ulnas had 70% of their coronoids cut. Fixation was performed with either a cannulated screw, a plate, or both a screw and a plate. Energy to failure, force at failure, first cycle stiffness, and stiffness at failure were measured on a servohydraulic testing machine under cyclic posterior axial loading.

RESULTS

The combination of a plate and screw had significantly greater energy to failure (83 Nm), force required to cause failure (634 N), and stiffness at failure (387 N/mm) compared to either an isolated plate (38 Nm, 474 N, 237 N/mm, respectively) or a screw (10 Nm, 279 N, 149 N/mm, respectively). For energy to failure and force required to cause failure, the plate group significantly outperformed the screw group. There was no significant difference in stiffness at the time of failure between the plate and screw groups.

CONCLUSIONS

For type 3 O'Driscoll coronoid fractures or nonunions when both a screw and a plate can be placed, the combination of these 2 fixation devices appears to produce significantly greater biomechanical stability than either fixation device alone.