Search

Background Fractures of the anteromedial facet of the coronoid in posteromedial rotatory instability of the elbow are classified into 3 subtypes based on their location. The purpose of this study was to analyze the fracture morphology of anteromedial facet fractures in their 3 subtypes (anteromedial rim, anteromedial rim + tip, and anteromedial rim + sublime tubercle [±tip]). Methods Three-dimensional computed tomography remodeling was used to evaluate anteromedial facet fractures in a consecutive series of 40 patients, all of whom were affected by posteromedial rotatory instability of the elbow. Characteristics of the fractures, including the number of fragments, size of fragments, plane of the fracture line, and involvement of the sublime tubercle and radial notch, were measured for each subtype of the anteromedial facet fractures. Results Each subtype had a typical fracture pattern and distinct size. The fracture subtype 1 showed a single-fragment fracture, subtype 2 showed either a single- or dual-fragment fracture, and subtype 3 showed either a dual- or triple-fragment fracture. The angle between the fracture line and the coronal plane was greatest in subtype 3 fractures. The surface area of the fragment was largest in subtype 3 fractures. The percentages of articular involvement of the sublime tubercle were 0% in subtype 1, 47% in subtype 2, and 79% in subtype 3. The percentages of articular involvement of the radial notch were 0% in subtype 1, 7% in subtype 2, and 8% in subtype 3. Conclusion Analysis with quantitative 3-dimensional computed tomography showed the characteristic morphology of each subtype of anteromedial facet fracture. Subtype 1 comprised 1 fragment with the smallest fragment size. Subtype 2 was a single- or dual-fragment fracture, the size of which should be considered in the treatment plan. Subtype 3 was a large fragment comprising the sublime tubercle. Our findings are significant because they highlight unique fracture morphology that may help surgeons to distinguish one fracture subtype from another in clinical practice.

Introduction The elbow joint is a compound joint made of articulations in between the humerus, ulna and the radius. The coupling areas (joints) are of prime importance from the kinetic-biomechanical perspective and of potential inter-ethnic significance. These articulations can be affected by several pathologies that may require medical and surgical interference. This experimental analysis aims to infer data in relation to the morphometry of the proximal segment of the ulna and its articular surfaces represented by the greater sigmoid notch (trochlear notch) and lesser sigmoid notch (radial notch). Methods A sample of fifty ulnae (n = 50, 27 right and 23 left) was studied in connection with; the surface area of the sigmoid notches (SA), weight of ulna, and the volume of proximal portion of ulna (including the olecranon process and reaching inferiorly to the lowest margin of the radial notch), the length of ulna (L). Longitudinal dimensional parameters were also studied including; the straight distance between the highest point (tip) of the olecranon and that of the coronoid process (OCD), and the mid-olecranon thickness in mediolateral (T1) and anteroposterior orientation (T2). Results It has been inferred that there were no significant differences in between right versus left ulnae and in relation to the majority of morphometric parameters with an exception for OCD (22.47 vs 20.75, p-value = 0.002). There was a positive correlation in between all the parameters, although the strongest associations were observed in between OCD, the area of the trochlear notch, and the weight of ulna. Discussion A precise conclusion was reached in relation to morphometry, volumetry and the pertinent biomechanics of the proximal segment of the ulna. Key findings are of value to biomedical engineers, medical professionals including orthopaedic surgeons and rheumatologists, evolutionary biologist, and physical anthropologist. Data from this study can be used to (reverse) engineer the perfect implant for the elbow joint.

Background Chronic posterior subluxation or dislocation of the radial head is uncommon and difficult to treat. To restore radiocapitellar alignment, procedures such as deepening of the notch using a high-speed burr have been described, but they can result in cartilage damage. We hypothesized that a radial notch labralization using soft tissue could improve radiocapitellar tracking without violating the joint surface. Methods A radial notch labralization was performed in 3 patients with chronic posterior subluxation of the radial head and developmental dysplasia of the radial notch in the setting of complex recurrent instability of the elbow. A soft tissue graft (typically a portion of an allograft hamstring tendon) was used to create a meniscus-like bumper posteriorly, thereby deepening the radial notch and reducing its radius of curvature. A corrective anterior opening wedge ulnar osteotomy was also performed to realign the radial head with the capitellum. Results At a mean follow-up of 32 months, all 3 patients were pain free and had maintained a stable joint, with a functional range of motion. Each patient gave a rating of either "Greatly Improved" or "Almost Normal" on the Summary Outcome Determination scale. Radiographs performed during the last follow-up showed improved radiocapitellar alignment. Conclusion Chronic posterior subluxation or dislocation of the radial head can occur subsequent to developmental joint changes. The radial notch labralization using a soft tissue graft associated with a corrective ulnar osteotomy was successful in restoring radial head stability and avoiding cartilage damage.

The elbow is a complex articulation comprising the radius, ulna, and humerus. The radius and ulna function in concert with the distal humerus to allow flexion and extension at the elbow, while the radius and ulna separately allow supination and pronation. As a main transfer point of forces between the upper and lower arm, the elbow serves as the insertion site for a number of muscle tendons, all of which exert substantial forces at their attachment sites. During infancy, the elbow’s articular surfaces cannot be seen radiographically, as they are not as yet ossified. As the child grows, an ordered progression of ossification occurs at the secondary centers as the elbow joint gradually reveals its structure. The capitellum is the first secondary ossification center to ossify, occurring at about 1 year of age. Next, the radial head ossifies at about 3 years of age, followed by the internal (medial) epicondyle at 5 years, the trochlea at 7 years, the olecranon at 9 years, and finally the lateral epicondyle at 11 years. The progression lends itself to an easy mnemonic (“CRITOE”) with the ossification progressing approximately every 2 years in most cases. Some variability in the age of ossification of the various centers is common. When faced with an unusual pattern of ossification, views of the contralateral elbow can be very helpful. In truly difficult cases, advanced imaging may be needed, primarily ultrasound and magnetic resonance imaging (MRI). The configuration of the various ligaments and tendons about the elbow is the same as in the adult. The ulnar collateral ligament (UCL) medially has anterior, posterior, and transverse bands of which the anterior and posterior bands are most important. The anterior band spans the gap from the medial epicondyle to the sublime tubercle (Figure 1A). The posterior band is the weaker of the two and extends from the medial olecranon to the posterior aspect of the medial epicondyle (Figure 1B). Laterally, the radial collateral ligament and the lateral band of the UCL are the main restraints to varus stress, with the latter being the primary support. Both arise from the lateral epicondyle. The lateral band of the UCL wraps along the underside of the radius, cradling it, and inserts on the lateral ulna at the supinator crest (Figure 1A). The annular ligament, as its name suggests, encircles the radial head with insertions on the posterior and anterior aspects of the ulna at the radial notch. Figure 1. Twelve-year-old boy. A, coronal T2 fat-saturated magnetic resonance. The anterior band of the ulnar collateral ligament stretches from the underside of the medial epicondyle to the sublime tubercle (arrowheads). The lateral band of the ulnar collateral ... Given its varied appearance and multiple-tendon and ligamentous appearance, a multimodality approach to elbow imaging is best. Especially in pediatrics, radiographs remain the mainstay of initial investigation, since they are fast and inexpensive and usually include sufficient information to guide therapy in the majority of cases. However, other modalities make substantial contributions to the diagnosis and care of both acute and chronic injuries about the elbow through childhood and adolescence. Computed tomography scanning with its multiplanar capability is adept at producing highly intelligible images with excellent resolution. Ultrasound has the advantage of not requiring ionizing radiation but tends to be a more focused examination without the ability to obtain a global picture of the joint. MRI is the primary advanced imaging modality, as it does not require ionizing radiation and can visualize bone as well as articular, physeal, and epiphyseal cartilage. The key to understanding elbow injuries in the child is an appreciation of the weak links in the structure of the elbow. The physis is a mainly columnar aggregation of chondrocytes with scant intervening matrix. As such, it is always weaker than bone and is much more likely to fail in the face of acute or chronic repetitive trauma. Much of pediatric elbow imaging focuses on the evaluation of the multiple growth centers and their physes about the elbow. The distal humerus also includes a thin supracondylar portion, which, when exposed to the force of the olecranon, is much more likely to fracture compared with the more substantial physes at the larger portion of the distal humerus. Supracondylar fractures are common as an acute sports injury, as are lateral and medial condylar fractures. In many cases, after acute trauma no fracture will be noted on conventional radiographs. However, prominent anterior and posterior fat pads indicate a joint effusion and alert the physician of the likelihood of an occult fracture (Figure 2). The elbow can then be immobilized. Follow-up films done 10 to 14 days later will commonly show periosteal reaction, indicating that a fracture had indeed occurred. Figure 2. Six-year-old boy. Lateral view of the elbow demonstrates a prominent anterior far pad (arrowhead) and posterior fat pad (arrow). A fracture of the proximal ulna is present (curved arrow) As children grow and mature, they participate in sports in a more goal-directed manner. In addition to a greater time actually playing sports, a greater amount of time is spent practicing. The greater load of repetitive motion leads to an increased incidence of overuse injuries about the elbow. As the ossification centers about the elbow develop and mature, the pattern of injury changes as well. In the United States, sports-related injuries of the pediatric elbow mainly result from baseball and gymnastics. During throwing, the arm is extended posteriorly, or “cocked,” and then accelerated forward to propel a projectile toward the target. During the late phase of cocking and early acceleration, a large hyperextension and valgus force is placed on the elbow. The result is a lateral compressive force centered on the developing capitellum laterally where the pattern of injury depends on the state of maturation of the capitellum. A great tensile or distractive force is concurrently borne by the medial supporting structures. Here again, the injury changes with age as the skeleton goes through its predictive pattern of maturation. Although the actual mechanism of injury is identical to the syndrome of valgus extension overload common in adult professional baseball pitchers, the appearance changes since the skeletal structures are different. A typical pattern of injury emerges. Laterally, Panner disease is seen first. This injury is thought to be an osteochondrosis of the capitellum seen in athletic individuals less than about 12 years old. In athletes older than 11 years, osteochondritis dissecans (OCD) occurs and is akin to OCD elsewhere in the body, as at the femoral condyles and talus. As can be seen, there is some overlap in the age ranges in the 2 syndromes reflecting to a certain extent their common etiologies. In skeletally mature individuals, true osteochondral fractures of the capitellum may occur. Medially, injuries also progress in a fairly predictable manner. In younger adolescents, the medial epicondyle with its relatively weak physis is mainly affected. As physeal fusion nears, the focus of the injury shifts to the UCL as the main restraint to valgus forces is overcome. At the medial margin, many mixed forms are present such that partial tears of the UCL may coexist with chronic physeal injury at the medial epicondyle. Interestingly, chronic physeal injury at the medial epicondyle weakens it and may result in a complete avulsion of the entire medial epicondyle with displacement. Posteriorly, the main injury is to the olecranon at the level of the physis. Here the triceps caused a chronic avulsive injury to the olecranon physis and persistence of the olecranon physis. In addition to injuries related to throwing a baseball, elbow injuries related to gymnastics are also very common. The pursuit of excellence in gymnastics requires long hours of training in which the same routines and exercises are practiced repetitively such that the arms are subjected to a remarkable degree of repetitive stress. Injuries at the wrist are well documented and include a range on injuries whose manifestation depends on the skeletal maturation of the athlete. Elbow injuries are also common and include some of the same injuries that baseball players sustain especially laterally. Apart from acute fractures, football injuries are underrepresented in the scope of injuries about the elbow. The reason for this discrepancy is related to the actual shape of the football as opposed to the baseball. A baseball is small and round and fits easily into the palm of the hand. It is meant to be thrown, and indeed, all the players on the field, not just the pitcher, throw the baseball an enormous number of times. In contradistinction, the football is not a ball that is easy to throw. It is far heavier than a baseball and does not lie well in the hand. It is much more difficult to throw hard so that the throwing motion is far less extreme in terms of the acceleration of the arm and the extent of cocking that occurs during throwing. In addition, most of the players on a football team do not ordinarily throw the ball. In fact, most of the players on a team do not touch the ball at all during the course of the game.

To develop a schematic segmentation of the proximal ulna in order to detect, assess the frequency, and characterize the bony outgrowths arising from the trochlea and from the radial notch of the ulna, to enable differentiation of osteophytes from enthesophytes. Eighty well-preserved ulna specimens from the collection of the San Diego Museum of Man were analyzed by two musculoskeletal radiologists. The trochlea and the radial notch of the ulna simulate the shape of a clock quadrant. The proximal ulna was divided into 24 anatomic areas. The relationships of the joint capsule and insertions of tendons and ligaments onto these area were assessed by the two readers, and the resulting appearances of bony outgrowths were compared at visual inspection and on Radiographs. The interobserver visual comparison was good in 17 areas out of 24, but poor correlation was found in 7 areas. In one case, difficulties in differentiating osteophytes originating from the brachialis muscle/ tendon (area 9) from an enthesophyte originating from the capsule insertion on the coronoid process (areas 2 or 3) occurredand between two different enthesophytes in a further case. Five cases had difficulties in defining differences in the grading system of the outgrowths. The percentage of outgrowths observed in each of the areas was globally high, especially in areas 9 and 10. On radiographs it was possible to observe irregularities in ten areas; in eight at a threshold of height of 2 mm (areas 1-4, 9, 10, 11, 14) and in two at a threshold of height of 3 mm (areas 5, 6). The two readers had the same difficulties in differentiating enthesophytes from osteophytes at radiographic and visual examination. Our segmentation scheme is reproducible and objective, and permitted the differentiation of the bony outgrowths arising from the proximal ulna into osteophytes and enthesophytes, which may be particularly useful for the in vivo assessment of abnormalities seen in elbow overuse syndromes.

We examined radiographs of the elbows of the pitching arms of 79 professional baseball pitchers (mean age, 25.1 years; mean duration of professional career, 4.7 years) and noted the frequency and size of spurs, bone fragments, and intra-articular loose bodies according to site. The influence of duration of professional baseball career on these osteoarthritic changes was also investigated. The olecranon tip was the most frequent site of spurs (62/79; 78.5%), and fragmentation of the spur was detected in 17 joints. The frequency of spurs was also high at the medial margin of the olecranon, the tip of the coronoid process, the medial margin of the sigmoid notch, the medial margin of the trochlea and the olecranon fossa. In 38 subjects, spurs were observed at the distal portion of the radial notch of the ulna. However, few pitchers had osteoarthritic changes in the humeral capitellum or radial head. Intra-articular loose bodies were detected in 4 of 79 joints (5.1%), and bone fragments were present below the medial humeral epicondyle in 25 of 79 joints (31.6%). Osteoarthritic changes in the elbow joint appeared to be attributable mainly to traction stress and impingement associated with extension and valgus strain. Significant osteoarthritic changes were often found in professional pitchers whose careers exceeded 5 years.

The medial coronoid process (MCP) of the ulna takes part in the weight-bearing function of the elbow in quadrupedal animals. In this study, the timing of development of a solid subchondral bone layer (SBL) of the MCP in the dog is investigated, as this might be important in the pathogenesis of the fractured medial coronoid process, a common disease in young dogs of larger breeds. The SBL is considered to make an important contribution to the strength of the MCP. In this study, the SBL is visualized at the humeral articular side (H-side) and in the radial notch (RN) via three-dimensional reconstructions of micro-CT scans (34 μm voxel size) in nine young golden retrievers. After micro-CT scanning, the area was investigated histologically. Gradually, the appearance of the SBL on the H-side changes from a trabecular aspect to an even surface with gaps and finally to a completely even surface. The surface in the RN is still rough at 24 weeks after birth, although some consolidation has occurred. Initially, the enchondral ossification activity, as observed in the histological sections, is high, but later, when the intertrabecular spaces are filled in with calcified cartilage and bone, activity is less evident. Some vessels penetrated the SBL, but it is unclear if they account for all the gaps in the surface seen in micro-CT. In addition, the formation of a cortical structure of the proximal ulnar shaft could be visualized. The bony cortex is already even at the mediocaudal side of the proximal ulna 4 weeks after birth, but remains trabecular at the dorsal side until 6 weeks later. We hypothesize that the observed differences in the formation of an even SBL or cortex can be explained by mechanical factors. A smooth cortical layer has an even thickness and will be stronger than a cortex with varying thickness. In the MCP, compressive forces exerted by the humerus may be responsible for the early smoothening on the H-side. In the proximal ulna, the resistance to bending in the sagittal plane will depend mainly on the caudal surface of the ulna (and dorsal surface of the radius), surfaces furthest away from the neutral axis. At least the caudal ulna smoothened first, thus providing stiffness against bending at an early age. © 2005 Wiley-Liss, Inc.

Background: Lateral ulnar collateral ligament (LUCL) reconstruction requires proper understanding and identification of anatomic structures about the lateral elbow. The insertion site of the LUCL is based on the supinator tubercle. Purpose: To characterize the supinator tubercle relative to other surrounding anatomic landmarks. Study Design: Descriptive laboratory study. Methods: Computed tomography (CT) scans of 10 adult elbows were retrospectively reviewed. These CT scans were converted into patient-specific 3-dimensional computer models. Using a user-defined coordinate system, an ulnar Cartesian coordinate system was defined with anatomic landmarks as reference points to standardize the position of each model. The length of the supinator crest was measured. Following this, the crest was examined for a distinct raised bony tuberosity that would be consistent with the supinator tubercle. If no distinctly raised tubercle was noted, the most prominent appearing location of the crest distal to the radial notch was considered the tubercle. The distance from the proximal radial head junction to the supinator tubercle was recorded. Finally, the distance from the supinator crest at the radial head junction to the posterior cortex in the sagittal plane was measured. Results: The supinator tubercle was found to be prominent in 5 of 10 ulnar models. The supinator crest was 43.59 ± 13.28 mm long, and the supinator tubercle lateral extrusion was 5.60 ± 0.90 mm. The distance between the radial head junction and the supinator tubercle was found to be 15 ± 2.37 mm, and the distance from the supinator crest at the radial head junction to the posterior cortex was 10.25 ± 2.07 mm. Conclusion: The supinator tubercle is frequently not prominent or easily recognizable. Its relationship to other structures is of value. The proximal border of the radial head, residing 15 mm proximal to the most predictable location of the supinator tubercle, is a useful landmark when drilling tunnels during LUCL reconstructions. Clinical Relevance: Results of this study may aid proper anatomic LUCL reconstruction.

Understanding the anatomical relationships in the region of the supinator muscle is crucial in limiting surgical morbidity. The course, length, and muscular innervations of the posterior interosseous nerve, as well as a detailed dissection of the supinator muscle, were described and recorded in 31 specimens from 16 adult cadavers. In our study, the radial nerve bifurcated into the posterior interosseous nerve and superficial radial nerve 8.0 +/- 1.9 cm distal to the lateral intermuscular septum. The bifurcation of the radial nerve occurred 3.6 +/- 0.7 cm proximal to the leading edge of the supinator, with the posterior interosseous nerve exiting the supinator muscle 3.8 +/- 0.9 cm distal to the proximal margin. The arcade of Frohse was membranous in 68% of our specimens and tendinous in 32%. The supinator had one semicircular head or layer in 71% of specimens and 2 distinct heads or layers, as defined by diverging muscle fibers, in 29%. With 2 heads, or layers, the superficial layer extended to the lateral epicondyle while the deep layer extended to the ulna, below the radial notch.

Elbow dysplasia is osteoarthrosis/degenerative joint disease due to abnormal development of the elbow joint. The abnormal development is the result of specific inherited etiologies alone or in combination. This paper attempts to clarify the diagnosis of elbow dysplasia based on the presence of degenerative joint disease by correlating radiographic, necropsy, and histopathologic results using elbows from 8 German Shepherd dogs. All elbows had radiographic changes consistent with osteoarthrosis/degenerative joint disease which were identified best on the flexed medial-lateral projection. Radiographically, a specific diagnosis was made in seven elbows; ununited anconeal process (6) and osteochondrosis (1). At necropsy these lesions were confirmed plus 14 elbows were identified that had fragmented medial coronoid process (6), abnormally shaped medial coronoid processes or fissures in the articular cartilage of the medial coronoid process (8). Additionally, histopathologically there was proliferative synovitis at the radial notch of the ulna and degenerative changes on the proximal, nonarticular surface of the anconeal process at the site of insertion of the olecranon ligament and joint capsule. Therefore, for screening the elbow joint to identify elbow dysplasia, the recognition of osteoarthrosis/degenerative joint disease on an extreme flexed mediolateral radiograph appears to be sufficient.

The proximal radio-ulnar joint has two different types of articular surfaces. The contact area between the articulating surfaces is at its greatest when the joint is in a middle position. The highest density of osseous material is found on the ulnar side of the head of the radius. The subchondral bone beneath the radial notch of the ulna has a higher density at the edges than in the middle. In photoelastic experiments the intensity and configuration of isochromatics correspond to the material density of the osseous tissue of ulna and radius. The analysis of spongiosa near the joint shows bands of compressive cancellous trabeculae radiating axially into the subchondral cortex, crossed at right angles by bands of tensile cancellous trabeculae. These findings are in agreement with the course of the trajectories found in photoelastic experiments. The composition of the annular ligament is variable. The palmar and dorsal parts are made up of firm connective tissue; opposite the radial notch of the ulna, however, cartilage cells are embedded in the ligament. The histological composition of the annular ligament and the cancellous architecture in the radius and the ulna are in agreement with Pauwels' (1963) hypothesis that part of the compressive force in the elbow joint is transferred to the proximal radio-ulnar joint via the annular ligament. The distribution of the material in the subchondral bony tissue indicates that there is only partial contact between the radial head circumference and the radial notch of the ulna in all positions of the joint.

The elbow joint is formed by the distal end of the humerus and the proximal ends of the radius and ulna. The superior radio-ulnar joint, between the head of the radius and the radial notch of the ulna and annular ligament, has a joint cavity continuous with that of the elbow joint. The inferior radioulnar joint, between the head of the ulna and the ulnar notch of the radius, has no communication with the wrist joint as a rule. The union by the interosseous membrane of the shafts of the radius and ulna is, by strict definition, a fibrous joint between the radius and ulna and is sometimes called the middle radio-ulnar joint.

Anatomical and pathological descriptions of five congenital elbow luxations and subluxations in three dogs were based on palpation, radiographs, gross dissection and in one dog, surgical correction. The primary defect in all five joints was hypoplasia, or aplasia, of the medial collateral ligament. The osseous deformities consisted of outward rotation of the proximal ulna, hypoplasia, or aplasia, of the coronoid process, anconeal process and radial notch and a shallow trochlear notch. The proximal ulna was rotated approximately 40–45°. The olecranon was deviated laterally and dorso-cranially. The syndrome was compared with the deformities of congenital luxation of the radial head in children. An embryonic pathogenesis for congenital elbow luxations in dogs was hypothesized.