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Classifications in Brief: Regan-Morrey Classification of Coronoid Fractures
... The Regan-Morrey classification was used to classify coronoid fractures based on the results of CT scans preoperatively. 8 Radial head fractures were classified according to the original Mason classification. 9 ...
... The coronoid process fracture was addressed first, according to the Regan-Morrey classification. 8 Fixation of the coronoid process was performed for type II and III fractures, while type I coronoid tip fractures did not require fixation. The radial head fracture was then repaired or replaced with an artificial implant according to the fracture pattern and bone quality. ...
Introduction
Treating a terrible triad injury of the elbow remains a challenge for orthopedic surgeons, especially in elderly patients due to the poor quality of the surrounding soft tissue and bony structures. In the present study, we propose a treatment protocol using an internal joint stabilizer through a single posterior approach and analyze the clinical results.
Materials and Methods
We retrospectively reviewed 15 elderly patients with terrible triad injuries of the elbow who underwent our treatment protocol from January 2015 to December 2020. The surgery involved a posterior approach, identification of the ulnar nerve, bone and ligament reconstruction, and the application of the internal joint stabilizer. A rehabilitation program was initiated immediately after the operation. Surgery-related complications, elbow range of motion (ROM), and functional outcomes were evaluated.
Results
The mean follow-up period was 21.7 months (range, 16-36 months). ROM at the final follow-up was 130° in extension to flexion and 164° in pronation to supination. The mean Mayo Elbow Performance Score was 94 at the final follow-up. Major complications included breaking of the internal joint stabilizer in 2 patients, transient numbness over the ulnar nerve territory in one, and local infection due to irritation of the internal joint stabilizer in one.
Conclusions
Although the current study involved only a small number of patients and the protocol comprised two stages of operation, we believe that such a technique may be a valuable alternative for the treatment of these difficult cases.
Level of Clinical Evidence
4.
... And the DASH score (Disabilities of the Arm, Shoulder, and Hand Questionnaire) [17]. Coronoid Fractures were identified with Regan-Morrey Classification [18]. Radial head fractures were identified with Mason Classification [19]. ...
... The Regan and Morrey classification system is widely used, but a limitation of this classification system, already described [11], is the lack of a specific thresholds to define Types I and II fractures with potential overlap between the two types. This classification does not fully describe the progressive loss of joint congruence in a fracture setting and does not give any precise information about the intrinsic stability of the elbow, especially in those cases in which the clinicians do not have pre-trauma radiographs available. ...
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.
... There are many different surgical techniques and surgical approaches for each component of this triad. Each technique has proven to add some benefit to improve elbow stability or reduce associated complications [15][16][17][18]. No single surgical technique -to our knowledge-has been determined more superior than others [19].Planning to manage these types of injuries have to take into consideration tailored indications and patient needs [19]. ...
Objectives: Complex elbow fractures have a predisposition for undesirable outcomes even with surgical
management. The aim of this study was to evaluate the functional outcome of patients with traumatic
unstable elbow Injuries that were managed surgically, as well as how to select the proper surgical
approach and fixation guided by pre-operative planning. Analyzing their functional outcomes would
help formulate future evidence-based guidelines on elbow terrible triad injury management in clinical
practice.
Methods: All the surgical cases for Traumatic Unstable Elbow Injuries were collected from a single
tertiary hospital in the country that deals exclusively with these types of injuries. The database included
19 patients that were treated between 2013 until 2018. All the patient agreed to participate in this study.
They were asked to fill in the Mayo Elbow Performance Score (MEPS) at baseline first clinic after hospital
discharge, and later at final follow up after completion of physiotherapy. Both functional outcomes and
complications were correlated with clinical and radiological evaluation.
Results: A total of 19 cases of terrible triad of the elbowwereincluded in the studyanalysis. The study
sample included 19 participants (31.6% females and 68.4% males). Results showed that MEPS and ROM
significantly improved after the completion of follow up compared to the baseline. The median extension
score decreased from 20 to 10 (P < 0.05). The median flexion score increased from 122 to 140 (p = 0.001
using Wilcoxon signed-rank test). The median supination score increased from 45 to 80 (p< 0.05) while
the median pronation score increased from 42.5 to 70 (p = 0.05). The median MEPS scores significantly
increased from 60 to 85 (p< 0.001). When analyzed as a categorical variable, results showed that the
percentage of patients with good MEPS score increased from 21.1% to 68.4% (p< 0.001 using McNemar’s
test).
In terms of complications, 6 of the 19 patients needed a second surgical intervention with joint stiffness
as the leading cause
Conclusion: Terrible triad injuries of the elbow are a result of high energy trauma. These types of injuries
lead to unstable elbows that requires surgical intervention, extensive post-operative physiotherapy and
a high possibility of reoperation is required. We conclude that good outcomes after this injury can be
achieved by adequate preoperative planning, stable fixation, aggressive rehabilitation, regular outpatient
follows-up and complication anticipation and management.
Background:
Varus posteromedial rotatory instability is a relatively rare elbow injury, that has been infrequently reported in published literature. We intended to evaluate the outcomes of surgical management of this rare injury with anteromedial coronoid fixation, and, in selected patients, lateral ulnar collateral ligament (LUCL) repair.
Methods:
Between 2017 and 2020, we identified 12 patients with anteromedial coronoid fractures, and a varus posteromedial rotatory instability, who underwent surgery for fixation of the coronoid fracture, with or without LCL repair. All the included patients were either O'Driscoll subtype 2-2, or subtype 2-3. All the 12 patients were followed up for a minimum of 24 months, and their functional outcomes assessed using the Mayo Elbow Performance Score (MEPS).
Results:
The mean MEPS recorded in our study was 92.08, and the mean range of elbow flexion achieved was 124.2°. The mean flexion contracture in our patients was 5.83°. Three of our twelve patients (25%) suffered from elbow stiffness even at final follow-up. The results were graded as Excellent in eight, Good in three, and Fair in one patient.
Conclusion:
Coronoid fractures and LUCL disruptions associated with varus posteromedial rotatory instability can be reliably managed by employing a protocol that combines radiographic parameters, as well as intra-operative assessments of stability. While surgical intervention successfully restored stability, there is a learning curve to the management of these injuries and complications are not uncommon, particularly elbow stiffness. Hence, in addition to surgical fixation, emphasis should also be placed on intensive post-operative rehabilitation to improve outcomes.
Radiologists should be familiar with the typical surgical procedures applied at the elbow and aware of the spectrum of normal and pathologic appearances of posttreatment situations throughout all radiologic modalities. Most important in the case of posttraumatic surgical elbow procedures is correct postoperative elbow joint alignment, appropriate fixation of joint-forming fragments, and proper insertion of screws, plates, and anchor devices that do not conflict with intra-articular or bony structures. To report soft tissue repair procedures correctly, radiologists need to know the broad spectrum of different techniques applied and their appearance on magnetic resonance imaging.
Fractures and dislocations of the elbow are a common cause of emergency department visits each year. Radiography remains the bedrock of an initial injury assessment, and recognition of distinctive injury patterns based on fracture location, morphology, and severity, guides optimal clinical decision-making. This article reviews basic elbow anatomy, frequently seen fractures and injury patterns, and highlights how these findings influence surgical planning and patient management.
Introduction:
Terrible triad (TT) of the elbow is an association at high risk of instability. Treatment aims to restore joint stability. Lateral collateral ligament (LCL) repair is systematic, whereas medial collateral ligament (MCL) repair is only exceptionally necessary. The main aim of the present study was to assess clinical results in TT surgery. The secondary objective was to compare clinical progression with versus without MCL repair.
Material and methods:
A retrospective study included 50 TTs operated on via an isolated lateral or combined medial-lateral approach. Clinical assessment comprised MEPS, QuickDASH, VAS, flexion-extension and pronation-supination, and return to work and sport. Subgroup analysis was made according to associated MCL repair.
Results:
50 patients (19 female, 31 male) were operated on between January 2006 and January 2017. Mean follow-up was 24 months. At last follow-up, mean MEPS was 89.1, VAS 0.7, QuickDASH 16, flexion-extension 114°, and pronation-supination 137°. Only MEPS was significantly improved by MCL repair (p = 0.02), with no significant difference in complications.
Discussion:
TT surgery with immediate mobilization gave good long-term functional results, not significantly improved by MCL repair. The lateral approach should be adopted in first line, with the medial approach in second line in case of persistent instability after lateral osteo-ligamentous repair.
Level of evidence:
IV; retrospective study.
Complex elbow fractures are exceedingly challenging to treat. Treatment of severe distal humeral fractures fails because of either displacement or nonunion at the supracondylar level or stiffness resulting from prolonged immobilization. Coronal shear fractures of the capitellum and trochlea are difficult to repair and may require extensile exposure. Olecranon fracture-dislocations are complex fractures of the olecranon associated with subluxation or dislocation of the radial head and/or the coronoid process. The radioulnar relationship usually is preserved in anterior but disrupted in posterior fracture-dislocations. A skeletal distractor can be useful in facilitating reduction. Coronoid fractures can be classified according to whether the fracture involves the tip, the anteromedial facet, or the base (body) of the coronoid. Anteromedial coronoid fractures are actually varus posteromedial rotatory fracture subluxations and are often serious injuries. These patterns of injury predict associated injuries and instability as well as surgical approach and treatment. The radial head is the bone most commonly fractured in the adult elbow. If the coronoid is fractured, the radial head becomes a critical factor in elbow stability. Its role becomes increasingly important as other soft-tissue and bony constraints are compromised. Articular injury to the radial head is commonly more severe than noted on plain radiographs. Fracture fragments are often anterior. Implants applied to the surface of the radial head must be placed in a safe zone.
A review of thirty-five patients who had a fracture of the coronoid process of the ulna revealed three types of fracture: Type I--avulsion of the tip of the process; Type II--a fragment involving 50 per cent of the process, or less; and Type III--a fragment involving more than 50 per cent of the process. A concurrent dislocation or associated fracture was present in 14, 56, and 80 per cent of these patients, respectively. The outcome correlated well with the type of fracture. According to an objective elbow-performance index used to assess the results for the thirty-two patients who had at least one year of follow-up (mean, fifty months), 92 per cent of the patients who had a Type-I fracture, 73 per cent who had a Type-II fracture, and 20 per cent who had a Type-III fracture had a satisfactory result. Residual stiffness of the joint was most often present in patients who had a Type-III fracture. We recommend early motion within three weeks after injury for patients who have a Type-I or Type-II fracture. Reduction and fixation, followed by early motion when possible, may be the preferred treatment for patients who have a Type-III fracture.
Background:
Terrible triad injury (TTI), one of the main patterns of complex elbow instability, is difficult to treat and yields conflicting surgical results. We analyzed prospectively a series of patient affected by TTI and treated according to the current diagnostic and surgical protocols to investigate whether their application allow to obtain more predictable outcomes.
Material and methods:
We analyzed 26 patients with a mean age of 52 years. Preoperative X-rays and CT were performed; all patients were operated by the same elbow surgeon and underwent the same surgical and rehabilitation treatment. Final functional outcome was assessed by the Mayo Elbow Performance Score (MEPS), Quick-Disability of the Arm Shoulder and Hand-score (Q-DASH) and the modified-American Shoulder and Elbow Surgeons score (m-Ases). A radiographic evaluation was also performed.
Results:
Mean follow-up was 31 months. At final evaluation, mean flexion, extension, supination and pronation were 137°, 10°, 77° and 79°, respectively; mean MEPS, m-ASES and Q-DASH scores were respectively 96, 91 and 8 points. Complications observed after first surgery were: elbow stiffness in 5 cases, mild posterolateral instability in 3 cases, chronic subluxation in 1 case. Radiographic evaluation showed secondary arthritis in 9 cases, symptomatic HO in 3 cases and late hardware displacement in 2 cases. Six out of 26 patient underwent reoperation with final satisfactory results.
Conclusion:
The current diagnostic and therapeutic protocols allow obtaining satisfactory clinical outcomes in majority of cases but a high number of major and minor unpredictable complications persist yet. In this series, low compliance, obesity, and extensive soft elbow tissue damage caused by high-energy trauma represented negative prognostic factors unrelated to surgery. On the other hand, the strict application of current algorithms by an expert elbow surgeon appears to improve clinical results by reducing the influence of other avoidable negative prognostic factors well known in current literature, such as the incomplete recognition of injuries, delayed treatment, inadequate treatment of bony and ligamentous injuries, prolonged immobilization and, last but not least, the surgeon's inexperience.
Level of evidence:
Level IV, Case series, Treatment study.
Of 110 elbow dislocations seen during a 15-year period at the Mayo Clinic, two were anterior and 108 were varieties of posterior dislocations. Dislocation commonly resulted in rupture of the collateral ligament attachments and in late slight heterotopic bone formation in the collateral ligaments. Avulsions of the epicondyles and fracture of the radial head were common accessory fractures. Avulsion of the medical epicondylar epiphysis is frequent and may predispose the joint to further injury. Injury to the ulnar nerve was approximately three times more common than was injury to the median nerve. Arterial injuries were noted in six dislocations and were always associated with persistent neurological findings. The late results were largely dictated by the severity of the original injury. The outlook in uncomplicated dislocations is good.
Purpose:
To determine if specific coronoid fractures relate to specific overall traumatic elbow instability injury patterns and to depict any relationship on fracture maps and heat maps.
Methods:
We collected 110 computed tomography (CT) studies from patients with coronoid fractures. Fracture types and pattern of injury were characterized based on anteroposterior and lateral radiographs, 2- and 3-dimensional CT scans, and intraoperative findings as described in operative reports. Using quantitative 3-dimensional CT techniques we were able to reconstruct the coronoid and reduce fracture fragments. Based on these reconstructions, fracture lines were identified and graphically superimposed onto a standard template in order to create 2-dimensional fracture maps. To further emphasize the fracture maps, the initial diagrams were converted into fracture heat maps following arbitrary units of measure. The Fisher exact test was used to evaluate the association between coronoid fracture types and elbow fracture-dislocation patterns.
Results:
Forty-seven coronoid fractures were associated with a terrible triad fracture dislocation, 30 with a varus posteromedial rotational injury, 1 with a anterior olecranon fracture dislocation, 22 with a posterior olecranon fracture dislocation, and 7 with a posterior Monteggia injury associated with terrible triad fracture dislocation of the elbow. The association between coronoid fracture types and elbow fracture-dislocation patterns, as shown on 2-dimensional fracture and heat maps, was strongly significant.
Conclusions:
Our fracture maps and heat maps support the observation that specific patterns of traumatic elbow instability have correspondingly specific coronoid fracture patterns. Knowledge of these patterns is useful for planning management because it directs exposure and fixation and helps identify associated ligament injuries and fractures that might benefit from treatment.
Clinical relevance:
Two-dimensional fracture and heat mapping techniques may help surgeons to predict the distribution of coronoid fracture lines associated with specific injury patterns.
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.
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.
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.
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.
This study tests the hypothesis that 3-dimensional computed tomography (CT) reconstructions improve interobserver agreement on classification and treatment of coronoid fractures compared with 2-dimensional CT.
A total of 29 orthopedic surgeons evaluated 10 coronoid fractures on 2 occasions (first with radiographs and 2-dimensional CT and then with radiographs and 3-dimensional CT), separated by a minimum of 2 weeks. Surgeons classified fractures according to the classifications of Regan and Morrey and of O'Driscoll et al., identified specific characteristics, recommended the most appropriate treatment approach, and made treatment recommendations. The kappa multirater measure (kappa) was calculated to estimate agreement between observers.
Regardless of the imaging modality used, there was fair to moderate agreement for most of the observations. Three-dimensional CT improved interobserver agreement in Regan and Morrey's classsication (kappa(3-dimensional) = 0.51 vs kappa(2-dimensional) = 0.40; p < .001) and O'Driscoll et al.'s classifications (kappa(3-dimensional) = 0.48 vs kappa(2-dimensional) = 0.42; p = .009). There were trends toward better reliability for 3-dimensional reconstruction in recognition of coronoid tip fractures (kappa(3-dimensional) = 0.19, kappa(2-dimensional) = 0.03; p = .268), comminution (kappa(3-dimensional) = 0.41 vs kappa(2-dimensional) = 0.29; p = .133), and impacted fragments (kappa(3-dimensional) = 0.39 vs kappa(2-dimensional) = 0.27; p = .094), and in surgeons' opinions on the need for something other than screws or plate for surgical fixation (kappa(3-dimensional) = 0.31 vs kappa(2-dimensional) = 0.15; p = .138). Interobserver agreement on treatment approach was better with 2-dimensional CT (kappa(3-dimensional) = 0.27, kappa(2-dimensional) = 0.32; p = .015).
Three-dimensional CT reconstructions improve interobserver agreement with respect to fracture classification compared with 2-dimensional CT.
Diagnostic III.
It is postulated that fractures of the anteromedial facet of the coronoid process and avulsion of the lateral collateral ligament lead to posteromedial subluxation and arthritis of the elbow. It is not clear which injuries require internal fixation and whether repair of the lateral collateral ligament is sufficient. We hypothesized that increasing sizes and subtypes of anteromedial facet fractures cause increasing instability and that isolated lateral collateral ligament repair without fracture fixation would restore elbow stability in the presence of small subtype-I fractures.
Ten fresh-frozen cadaveric arms from donors with a mean age of 66.3 years at the time of death were used in this biomechanical study. Passive elbow flexion was performed with the plane of flexion oriented horizontally to achieve varus and valgus gravitational loading. An in vitro unconstrained elbow-motion simulator was used to simulate active elbow flexion in the vertical position. Varus-valgus angle and internal-external rotational kinematics were recorded with use of an electromagnetic tracking system. Testing was repeated with the coronoid intact and with subtype-I, subtype-II, and subtype-III fractures. Instability was defined as an alteration in varus-valgus angle and/or in internal-external rotation of the elbow. All six coronoid states were tested with the lateral collateral ligament detached and after repair.
In the vertical position, the kinematics of subtype-I and subtype-II anteromedial coronoid fractures with the lateral collateral ligament repaired were similar to those of the intact elbow. In the varus position, the kinematics of 2.5-mm subtype-I fractures with the lateral collateral ligament repaired were similar to those of the intact elbow. However, 5-mm fractures demonstrated a mean (and standard deviation) of 6.2 degrees +/- 4.5 degrees of internal rotation compared with a mean of 3.3 degrees +/- 3.1 degrees of external rotation in the intact elbow (p < 0.05). In the varus position, subtype-II 2.5-mm fractures with the lateral collateral ligament repaired demonstrated increased internal rotation (mean, 7.0 degrees +/- 4.5 degrees; p < 0.005). Subtype-II 5-mm fractures demonstrated instability in both the varus and valgus positions (p < 0.05). Subtype-III fractures with the lateral collateral ligament repaired were unstable in all three testing positions (p < 0.05).
This study suggests that the size of the anteromedial coronoid fracture fragment affects elbow kinematics, particularly in varus stress. The size of an anteromedial coronoid fracture and the presence of concomitant ligament injuries may be important determinants of the need for open reduction and internal fixation.
A series of 103 acute fractures of the coronoid process of the ulna in 101 patients was reviewed to determine their frequency. The Regan-Morrey classification, treatment, associated injuries, course and outcomes were evaluated. Of the 103 fractures, 34 were type IA, 17 type IB, ten type IIA, 19 type IIB, ten type IIIA and 13 type IIIB. A total of 44 type-I fractures (86%) were treated conservatively, while 22 type-II (76%) and all type-III fractures were managed by operation.
At follow-up at a mean of 3.4 years (1 to 8.9) the range of movement differed significantly between the types of fracture (p = 0.002). Patients with associated injuries had a lower Mayo elbow performance score (p = 0.03), less extension (p = 0.03), more pain (p = 0.007) and less pronosupination (p = 0.004), than those without associated injuries. The presence of a fracture of the radial head had the greatest effect on outcome. An improvement in outcome relative to that of a previous series was noted, perhaps because of more aggressive management and early mobilisation. While not providing complete information about the true details of a fracture and its nature, the Regan-Morrey classification is useful as a broad index of severity and prognosis.
This paper presents a series of 105 cases of fracture-dislocation of the elbow joint. All these fractures differ in mechanism, age of patient and method of treatment, so problems arise in classification. Causes can be grouped together more easily than in principles of treatment. The cases are classified into 2 major groups and 10 subgroups. Single fracture types are analysed and the optimal type of treatment is studied. As with all joint fractures, adequate reconstruction is obilgatory to remove all steps in the articular cartilage, and rigid fixation is mandatory except for the radial head, where excision is indicated. The different fracture types and their relevant operations are illustrated with examples.
Fractures of the coronoid process are rare as isolated injuries and usually are associated with significant, sometimes devastating trauma to the elbow. The classification system based on the degree of involvement has proven helpful to estimate prognosis and to help guide treatment. Severe fractures are generally associated with instability and portend a poor prognosis. Treatment by distraction, external fixation, and early motion has been encouraging.
A review of thirty-five patients who had a fracture of the coronoid process of the ulna revealed three types of fracture: Type I--avulsion of the tip of the process; Type II--a fragment involving 50 per cent of the process, or less; and Type III--a fragment involving more than 50 per cent of the process. A concurrent dislocation or associated fracture was present in 14, 56, and 80 per cent of these patients, respectively. The outcome correlated well with the type of fracture. According to an objective elbow-performance index used to assess the results for the thirty-two patients who had at least one year of follow-up (mean, fifty months), 92 per cent of the patients who had a Type-I fracture, 73 per cent who had a Type-II fracture, and 20 per cent who had a Type-III fracture had a satisfactory result. Residual stiffness of the joint was most often present in patients who had a Type-III fracture. We recommend early motion within three weeks after injury for patients who have a Type-I or Type-II fracture. Reduction and fixation, followed by early motion when possible, may be the preferred treatment for patients who have a Type-III fracture.
Regan and Morrey proposed a 3-type coronoid fracture classification observing that the incidence of concommitant elbow dislocation was proportional to fragment size. Elbow instability associated with coronoid fractures presumably is related to disrupted bony architecture and ineffective stabilizers attached to the free fragment. Twenty cadaveric elbows were dissected, measuring medial collateral ligament, anterior capsule, and brachialis muscle insertion loci on the coronoid. Radiographs were taken after radiopaque labeling of the stabilizer insertions. The anterior bundle of the medial collateral ligament insertion averaged 18.4 mm dorsal to the coronoid tip. Only in Type III fractures would it be attached to the free fragment. The capsule inserted an average of 6.4 mm distal to the coronoid tip. Rarely should Type I fractures result from a capsular avulsion, because only 3 of 20 specimens had the capsule inserting on the tip. The brachialis had a musculoaponeurotic insertion onto the elbow capsule, coronoid, and proximal ulna. The bony insertion averaged 26.3 mm in length, with its proximal margin averaging 11 mm distal to the coronoid tip. In only Type III fractures is the fragment large enough to include the brachialis bony insertion.
The current treatment of coronoid process fractures of the ulna is based on the classification system of Regan and Morrey. We found no biomechanical studies that specifically addressed the role of the coronoid process in elbow stability. In the present investigation, the elbows of cadavera were tested before and after fracture of the coronoid process to assess the stabilizing contribution of the coronoid process under axial loading.
Six fresh-frozen cadaveric elbows were tested mechanically. All soft tissue surrounding the elbow, including the skin, was left intact. An axial load compressing the elbow joint was applied along the shaft of the forearm in the sagittal plane. A displacement of fifteen millimeters per minute was applied until a load of 100 newtons was attained. Each elbow was tested in 15, 30, 45, 60, 75, 90, 105, and 120 degrees of flexion. Next, less than 25 percent, 25 to 50 percent, or more than 50 percent of the coronoid process was fractured with an osteotome under radiographic guidance, and the testing was repeated. Each elbow served as its own control, and one elbow was used for two tests; therefore, a total of seven situations were investigated. The difference in displacements between the intact and osteotomized elbows was measured.
There was no significant difference, at any flexion position, in posterior axial displacement between the intact elbows and the elbows in which 50 percent or less of the coronoid process was fractured (type I and type II) (p = 0.43). There were significant differences, across all flexion positions, in posterior axial displacement between the intact elbows and the elbows in which more than 50 percent of the coronoid process was fractured (type III) (p = 0.006). Specimens with a type-III fracture also showed a significant increase in displacement compared with specimens with a type-I or type-II fracture (p = 0.012). Specifically, from 60 to 105 degrees of flexion, a significant increase in posterior translation of up to 2.4 millimeters was found (p<0.05).
In response to axial load, elbows with a fracture involving more than 50 percent of the coronoid process displace more readily than elbows with a fracture involving 50 percent or less of the coronoid process, especially when the elbow is flexed 60 degrees and beyond.
Posterior dislocation of the elbow with associated fractures of the radial head and the coronoid process of the ulna has been referred to as the "terrible triad of the elbow" because of the difficulties encountered in its management. However, there are few published reports on this injury.
Eleven patients with this pattern of injury were evaluated after a minimum of two years. The radial head fracture had been repaired in five patients, and the radial head had been resected in four. None of the coronoid fractures had been repaired, and the lateral collateral ligament had been repaired in only three patients. All eleven patients returned for clinical examination, functional evaluation, and radiographs.
Seven elbows redislocated in a splint after manipulative reduction. Five, including all four treated with resection of the radial head, redislocated after operative treatment. At the time of final follow-up, three patients were considered to have a failure of the initial treatment. One of them had recurrent instability, which was treated with a total elbow arthroplasty after multiple unsuccessful operations; one had severe arthrosis and instability resembling neuropathic arthropathy; and one had an elbow flexion contracture and proximal radioulnar synostosis requiring reconstructive surgery. The remaining eight patients, who were evaluated at an average of seven years after injury, had an average of 92 degrees (range, 40 degrees to 130 degrees ) of ulnohumeral motion and 126 degrees (range, 40 degrees to 170 degrees ) of forearm rotation. The average Broberg and Morrey functional score was 76 points (range, 34 to 98 points), with two results rated as excellent, two rated as good, three rated as fair, and one rated as poor. Overall, the result of treatment was rated as unsatisfactory for seven of the eleven patients. All four patients with a satisfactory result had retained the radial head, and two had undergone repair of the lateral collateral ligament. Seven of the ten patients who had retained the native elbow had radiographic signs of advanced ulnohumeral arthrosis.
Elbow fracture-dislocations that involve a fracture of the coronoid process in addition to a fracture of the radial head are very unstable and prone to numerous complications. Identification of the coronoid fracture is therefore important, and computed tomography should be used if there is uncertainty. With operative treatment, the surgeon should attempt to restore stability by providing radiocapitellar contact (preserving the radial head when possible and replacing it with a prosthesis otherwise), repairing the lateral collateral ligament, and perhaps performing internal fixation of the coronoid fracture.
The most widely recognized coronoid fractures have been described as occurring in the coronal plane according to the amount of process detached from the ulna. Over the last few years, we have recognized that the coronoid fracture is a much more complex injury than originally thought. This report calls attention to an oblique, medial compression fracture of the coronoid, a fracture so subtle as to be missed by routine assessment but sometimes associated with joint subluxation or dislocation. The currently accepted classification system based on a simple fracture pattern in the coronal plane may be too simplistic to characterize fractures of the coronoid fully.
It has been suggested that specific types of coronoid fractures are associated strongly with specific patterns of traumatic elbow instability. This hypothesis was tested in a review of a large consecutive series of patients with a fracture of the coronoid as part of a fracture-dislocation of the elbow.
One surgeon repaired 67 coronoid fractures as part of a fracture-dislocation of the elbow over a 7-year period. Each coronoid fracture was characterized on the basis of surgical exposure. Pearson chi-square analysis was used to evaluate the association of the coronoid fracture type with 1 of 4 common patterns of elbow fracture-dislocation.
The coronoid fracture was associated with an anterior (6 patients) or posterior (18 patients) olecranon fracture-dislocation in 24 patients, an elbow dislocation and radial head fracture in 32 patients, and a varus posteromedial rotational instability pattern injury in 11 patients. Among the 24 patients with olecranon fracture-dislocations 22 had large coronoid fractures and 2 had small (<50%) coronoid fractures. All 32 patients with terrible-triad injuries had small (<50%) coronoid fractures with 1 of these being a fracture of the anteromedial facet of the coronoid. Among patients with varus posteromedial rotational pattern injuries 9 had small fractures of the anteromedial facet and 2 had larger fractures. The association of coronoid fracture type with injury pattern was strongly statistically significant for both classification systems.
The following strong associations were confirmed by this study: large fractures of the coronoid process with anterior and posterior olecranon fracture-dislocations, small transverse fractures with terrible-triad injuries, and anteromedial facet fractures with varus posteromedial rotational instability pattern injuries. An awareness of these associations and their exceptions may help guide the optimal management of these injuries.
Therapeutic, Level IV.
The coronoid fractures that occur in the terrible-triad pattern of traumatic elbow instability (posterior dislocation with fractures of the radial head and coronoid) usually are small transverse fragments. Attempts to classify these fragments according to height as suggested by Regan and Morrey have been inconsistent and contentious. The purpose of this study was to quantify coronoid fracture height in terrible-triad injuries.
The height of the coronoid process of the ulna and the coronoid fracture fragment were measured on computed tomography scans of 13 patients with terrible-triad-pattern elbow injuries. Two observers performed the measurements with excellent intraobserver and interobserver reliability.
The total height of the coronoid process of the ulna averaged 19 mm. The average height of the coronoid fracture fragment was 7 mm. This corresponds to an average of 35% of the total height of the coronoid process.
The transverse coronoid fractures associated with terrible-triad elbow injuries have a variable height that may not be easy to classify according to the system of Regan and Morrey. Classification of coronoid fractures according to fracture morphology and injury pattern may be preferable.
Coronoid injuries are classified according to the size of the coronoid fracture. The purpose of this study was to provide a detailed anatomic description of the coronoid process, with specific focus on the coronoid height, the coronoid width, and the olecranon-coronoid angle.
Thirty-five cadaveric arms were dissected. All soft tissue was removed and the ulna was disarticulated from the humerus, radius, and the carpal bones. A 3-dimensional digitizing system was used to locate 19 anatomic landmarks on each specimen. By using the 3-dimensional coordinates of the landmarks, the coronoid heights, proximal ulnar widths, and olecranon-coronoid angles were determined.
The coronoid height, with its base defined by the trough of the trochlear notch and the slope change of the distal coronoid process, measured 15 mm and was 42% of the ulnar height. The coronoid height, with its base defined by the transverse groove of the sigmoid notch at the guiding ridge and the distal insertion of the brachialis muscle, measured 15 mm and was 43% of the ulnar height. The olecranon-coronoid angle ranged between 33 degrees and 38 degrees .
For lateral radiographic classification of coronoid fractures, coronoid height is best defined by the trough of the trochlear notch and the slope change of the distal coronoid process. For anatomic studies, coronoid height is best defined by the transverse groove of the sigmoid notch at the guiding ridge and the distal insertion of the brachialis muscle. The olecranon-coronoid angle is best defined by the angle formed by the lines from the olecranon tip through the coronoid tip and through the slope change of the distal coronoid process. The coronoid anatomy measurements reported in this study may help to improve coronoid fracture classification.
Fracture of the anteromedial facet of the coronoid process has been recognized as an important type of coronoid fracture. We performed a quantitative analysis of 21 3-dimensional computed tomography scans to evaluate the degree to which the anteromedial facet protrudes as a distinct process separate from the proximal ulnar metaphysis. The distance between the center axis of the trochlear notch and the most medial edge of the anteromedial facet averaged 12.5 mm (range, 8.7-20.1 mm). The part of the maximum anteromedial facet width that was supported by the proximal ulnar metaphysis and diaphysis averaged 5.4 mm (range, 1.7-11.5 mm). On average, 58% of the anteromedial facet (range, 26%-82%) was unsupported by the proximal ulnar metaphysis and diaphysis. It is not surprising that this relatively vulnerable protrusion from the anteromedial facet of the coronoid is frequently a separate fracture fragment in complex traumatic elbow instability.