Olecranon stress fractures are a rare upper extremity fracture that primarily affects throwing athletes. The incidence of olecranon stress fractures are increasing owing to the number of patients playing and the volume of engagement in competitive sports, especially in the pediatric population. However, olecranon stress fractures can present a challenge from a management and a rehabilitation perspective owing to their vague presentation, thereby affecting how these patients are diagnosed and managed. Therefore, it is imperative to further evaluate the disease process, diagnosis, and treatment of this condition to best manage our patients.
Key points
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Olecranon stress fracture is an elbow injury that primarily affects athletes involved with throwing sports or other activities that emphasize repetitive motion of the elbow.
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Tenderness over the olecranon after or during throwing, especially the medial side, is a key physical examination finding suggestive of olecranon stress fracture.
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MRI has been reported as the gold standard for detecting stress fractures.
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Nonoperative treatment has been successful in the few reports of stress reactions in the literature. However, operative management is the mainstay treatment option.
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The return to sport rate after olecranon stress fracture is very high, with both nonoperative or operative management.
Introduction
Olecranon stress fracture (OSF) is an overuse elbow injury that primarily affects athletes who perform repetitive throwing motions. The first reported description of the injury was linked to a javelin thrower in 1946. Currently, baseball players are the most susceptible to this injury. The incidence of OSF in other sports such as wrestling, diving, gymnastics, and archery is also increasing. OSF can be a challenge to manage, because there is limited literature describing the disease process, diagnosis, and treatment of this condition. This article describes the epidemiology, anatomy, and pathophysiology of OSF and summarizes the current literature regarding diagnosis, management, and prognostic outcome of this condition.
Epidemiology
Stress fractures are rare injuries. Only 0.8% of fractures in high school athletes are stress related, and only 2.8% of those injuries involve the upper extremity. The olecranon has an incidence of 58% of stress fractures in baseball players. Pitchers are the most predominant position at risk of injury. OSF is increasing in prevalence in pediatric patients owing to the recent increased number of children participating in competitive sports (currently 45 million children in the United States play in organized youth sports). , This factor is of particular significance given that 31% of pediatric athletes experience elbow pain over the course of 1 year, with 5% of young baseball pitchers sustaining a serious throwing injury necessitating surgical repair or extended cessation of sport within 10 years.
Anatomy
The osseous anatomy of the elbow joint is complex, consisting of 3 functionally separate articulations: the proximal radioulnar, radiocapitellar, and ulnohumeral articulations. These articulations allow for a range of motion in extension and flexion from −5° to 140°, as well as forearm rotational motion from 90° pronation to 90° of supination. The olecranon’s importance lies in its role in articulating with the humeral trochlea ( Fig. 1 ). The humeral trochlea articulates with the proximal ulna via the sigmoid notch, and the olecranon is the most proximal aspect of this notch, with the coronoid process the most distal. Hence, the olecranon assists in creating a hinge motion in the elbow owing to its cupping of the lower end of the humerus.
Resistance to valgus stress is provided by the anterior band of the ulnar collateral ligament (UCL) and the radial head, whereas varus stress is countered by the lateral collateral ligament complex. , The triceps brachii and the anconeus insert onto the posterior third of the olecranon and proximal ulna, making the olecranon process periosteum and triceps tendon closely associated. Finally, the brachialis inserts onto the coronoid process of the ulna, which helps to distribute the compressive forces across the elbow joint during contraction.
Pathophysiology
Stress fractures occur owing to 2 mechanisms, the first being owing to an increased amount of cyclical repetitions occurring at a lower intensity than maximum bone strength on nonpathologic bone tissue. Although the intensity is not enough to cause an acute fracture at onset, the continued stress on the bone prevents it from appropriately remodeling. This abnormal remodeling process is the result of osteoblasts laying down bone at a rate slower than osteoclasts resorbing bone. Because remodeling and strengthening of bone is lagging behind resorption of damaged bone, microdamage accumulates over time. From this repetitive microdamage, a fracture can develop during normal sustainable loads.
Stress fractures may also occur owing to trabecular bone having insufficient density. Such bone has reduced mechanical properties at onset, therefore, even normal intensity loads are at higher risk of stress fractures over time. The most common example of this presentation is in female softball players when combined with poor diet, such as diminished calcium intake, or menstrual disturbances related to exercise. Although women are at increased risk for stress fractures owing to this specific mechanism, among athletes, the overall difference in incidence between men and women is minimal.
For baseball players in particular, OSF has been attributed to rapid and repetitive valgus extension. The UCL is the main ligamentous stabilizer for the medioposterior part of the elbow, and absorbs approximately 50% of the valgus stress (around 64 Nm) placed on the elbow. As rapid elbow extension occurs, the tip of the olecranon is forced into the olecranon fossa and, with increased laxity of the UCL comes a compensatory increase in compression on the medial aspect of the olecranon–olecranon fossa articulation during extension. Excessive tensile forces of the triceps on the olecranon during the acceleration phase of throwing also exacerbate this process. Aguinaldo and Chambers reported that there are several mechanical factors in the throwing motion that predispose the elbow to additional excessive valgus loads, including late trunk rotation, reduced shoulder external rotation, increased elbow flexion, and sidearm motions.
Additionally, recurrent UCL injuries, ranging from strains or minimal tears to multiple reconstructive procedures, increase the laxity and subsequent contact pressure in the posteromedial aspect of the elbow during extension. This process is also associated with medial epicondylar apophysitis and avulsion fractures ( Fig. 2 ) owing to repetitive stress placed on the medial elbow. This structure is vital for valgus stability because dynamic and static stabilizers attach here.
Pediatric population
Unlike the adult elbow, the pediatric elbow contains 6 active ossification centers that occur predictably depending on age: capitellum at 1 year, radial head and medial epicondyle at 5 to 6 years, trochlea and olecranon at 8 to 10 years, and lateral epicondyle at 10 years, with the sequence the same in both boys and girls, although boys tend to lag behind up to 2 years on average. The significance of open physes is that they present weak biomechanical points and are therefore more susceptible to failure when faced with increased or recurrent force. Open physes are weaker and less elastic and, unlike adults who have a high incidence of soft tissue failures, because the soft tissue tend to absorb the majority of biomechanical stresses, in pediatric athletes the physes absorb these biomechanical stresses.
During growth spurts, the growth plate is also at an increased risk for fracture owing to decreased physeal strength during this period, where bone mineralization lags behind linear bone growth, creating porous bone. Repetitive loading at this time can lead to altered metaphyseal perfusion, interfering with the mineralization of bone. Therefore, ischemic conditions and osseous necrosis with deformity of the developing ossification center may develop. Asymmetric or complete cessation of growth can also occur, decreasing the olecranon’s ability to handle repetitive stress.
Common risk factors seen in adolescent patients with OSF include average of 12 years of onset, playing a pitcher or catcher role in a throwing sport, playing more than 100 games a year, or throwing a breaking ball (a type of pitch that increases rotational and angular forces on the elbow), which has been recommended not be thrown before the age of 14 to 16 years, and increased velocity. ,
Clinical history
When assessing elbow pathology, the patient history is of utmost importance. Certain activities and distributions of discomfort can help to rule OSF in or out of the differential diagnosis. When dealing with a thrower, it is imperative to ask at what point in the throwing motion symptoms occur, because pitchers with pain medially at the onset of arm acceleration tend to have UCL pathology, whereas patients with posterior or posteromedial elbow pain at ball release (when the elbow nears terminal extension) should be evaluated further for OSF. Posterolateral pain may also be reported. Patients will also note loss of terminal elbow extension, hence an inability to complete their pitch, maintain control, or a sense of reduced velocity on the pitch.
Patients also most likely emphasize pain with repetitive motion, which may improve with rest, anti-inflammatory medication, icing, or compression. Extension of the elbow causes the most significant amount of pain, but patients also tend to report pain during pronation and supination of the forearm. Any discomfort will most likely be reported as increasing in intensity over time, as the bone becomes weaker to the point of failure.
Physical examination
The examiner should proceed with a complete elbow examination: inspection, palpation, range of motion, strength testing, stability testing, and a neurovascular examination. Inspect and palpate for any swelling at or near the olecranon and localize any tenderness over the region. Point tenderness to palpation over the olecranon, especially on the medial side, is a key physical examination finding suggestive of OSF, although posterolateral pain may also be elicited. Palpation of the ulnar nerve, UCL, distal medial triceps, and flexor–pronator group should also be performed to ensure that these nearby structures are not involved.
During range of motion testing, assess for pain that is reproducible with resisted elbow extension. Beforehand, it is important for the examiner to recognize that throwers tend to have some loss of elbow extension in their throwing elbow at baseline compared with their nonthrowing arm, and therefore, a minor comparable deficit of extension should not be a major concern. There are 2 focused examination maneuvers that often reproducibly elicit pain in patients with an OSF. The snapping extension test and the arm bar test. The snapping extension test, demonstrated in Fig. 3 , involves placing continuous valgus stress on the elbow followed by extension from 30° flexion to full extension. The examiner repeats the examination without valgus stress while palpating the posteromedial olecranon for tenderness. The arm bar examination, demonstrated in Fig. 4 , involves having the examiner place the fully pronated and extended elbow on his or her shoulder and applies downward pressure on the proximal forearm and midhumerus.
Diagnostic imaging
Early detection of OSF is important, because there is a statistically significant earlier return to sport or activity when a stress injury is appropriately diagnosed within 3 weeks of symptom onset compared with later than 3 weeks (return time of 10.4 weeks vs 18.4 weeks, respectively). Patients with OSF may or may not have radiologic findings. Plain radiographs of the elbow should be taken owing to their cost effectiveness and readily available access. Standard anteroposterior, lateral, and axial views should always be ordered; however, although not required, 2 oblique views may also be obtained to assist with better visualization of the posteromedial olecranon. Typical findings, as seen in Fig. 5 , include osteophyte formation in the posteromedial olecranon fossa, loose bodies from fragmentation of the capitellum, possible calcium deposits on the medial ulnar collateral ligament, and hypertrophy of the humerus resulting from decreased spacing for articulation of the olecranon process within the fossa. It is important to note that stress fractures may not appear on a typical radiograph if not significant enough in size. Therefore, if a stress fracture is suspected based on the physical examination and/or clinical judgment, but not confirmed via radiograph, additional imaging may be required.
