Knowledge of elbow ligament anatomy and its functional biomechanics is key to understanding the pattern of elbow injuries in various sports disciplines and in aiding accurate interpretation of imaging findings (Fig. 1). Medial and lateral ligamentous complexes offer primary stability to the elbow joint against valgus and varus strain, respectively. Medially, the ulnar collateral ligament (UCL) is composed of anterior bundle, posterior bundle, and transverse fibers [7–11]. The anterior bundle is the strongest component of the UCL and predominantly resists the valgus torque to the elbow [7, 8, 12–16]. The anterior bundle can be subdivided into anterior and posterior bands, both of which arise from the medial epicondyle and commonly insert into the sublime tubercle situated along the medial aspect of the base of the coronoid process of the ulna [8, 12, 17–20].

The anterior band of the UCL is the primary soft-tissue restraint against valgus stress at 60° and 90° and the primary corestraint at 120° flexion. As a result, injuries of the anterior band are more common between full extension to 90° flexion, and the incidence of posterior band injury increases with valgus strain in a greater degree of elbow flexion [8]. The posterior bundle of the UCL is anatomically smaller and functionally weaker and forms the floor of the cubital tunnel, deep to the ulnar nerve. The horizontally oriented fibers of the transverse bundle run along the medial joint line, between the coronoid and the olecranon processes of ulna, and functionally are the least significant component of the medial ligaments complex [7, 8, 11, 17, 21]. The lateral collateral ligamentous complex comprises the radial collateral ligament, lateral ulnar collateral ligament (LUCL), and annular ligament. In combination, the lateral collateral ligaments form the primary stabilizers of the elbow against varus stress. In addition, the annular ligament also contributes to rotational stability of the proximal radioulnar joint (PRUJ). Within the lateral compartment, the LUCL arises proximally from the lateral epicondyle and attaches distally to the supinator crest of ulna and functionally serves as the main stabilizer of the elbow against varus stress, akin to the anterior band of the UCL medially [1, 17].

UCL tears can be classified into proximal or humeral attachment tears, midsubstance tears, and distal or ulnar attachment tears. Most full-thickness tears are midsubstance tears, followed by distal and then proximal tears in order of frequency [13, 17]. Tears of the anterior bundle can be associated with bony avulsions of the medial epicondyle or the sublime tubercle. High-grade tears involving the lateral ligaments, particularly the LUCL, can result in chronic posterolateral rotatory instability [22]. Lateral ligament injury resulting from traumatic dislocation can be followed sequentially by injury to the medial ligaments in a circular fashion [23, 24].

At the London 2012 Summer Olympics, 10,568 athletes from 204 countries competed in 26 sports and 39 disciplines. Imaging facilities at the main polyclinic within the Stratford games village included a digital x-ray system for radiography, two ultrasound scanners (Logiq E9, GE Healthcare), a 64-MDCT scanner (Discovery CT750, GE Healthcare, and 3- and 1.5-T wide-bore MRI scanners (Discovery MR740w and Optima MR 450w, GE Healthcare). An integrated radiology information system–PACS and digital voice recognition system facilitated viewing images and issuing reports. Diagnostic investigations were reported and ultrasounds were performed by 27 experienced consultant musculoskeletal radiologists with at least 8 years of working experience in musculoskeletal radiology, operating on a shift system. The demographic data and imaging were initially analyzed by an imaging fellow at the 2012 Summer Olympic Games. Subsequently, all elbow images showing positive findings were reviewed independently by two senior fellowship-trained musculoskeletal radiologists. Discrepancies were resolved through consensus following discussion. Imaging findings for in-competition injuries were correlated with British Broadcasting Corporation London 2012 Summer Olympic Games videos in conjunction with the International Olympic Committee, where available.

Elbow ligament injuries seen on ultrasound and MRI at the 2012 Summer Olympic Games were broadly categorized into pure UCL and combination injuries that involved the UCL, radial collateral ligament, and LUCL. According to the anatomic location, UCL tears were classified as humeral attachment, ulnar attachment, and midsubstance tears. Humeral attachment tears were further categorized into undersurface tears, which included pure ligamentous injuries to the humeral attachment and avulsion bony injuries. Grade II and III ligament injuries, according to the American Medical Association classification [25], were referred to as high-grade ligament injuries. Avulsion ligament injuries were also regarded as high-grade injuries for the purpose of the study, because functionally these behave as grade III ligament injuries. O'Donghue type II and III muscle injuries were called high-grade muscle tears, and type I muscle injuries were referred to as low-grade tears [26].

Acute elbow injuries were seen in a wide variety of sports disciplines. MRI was the most commonly used imaging tool for investigating elbow ligament injuries during the 2012 Summer Olympic Games.

Elbow injuries in sports have been traditionally described in overhead-throwing athletes, particularly baseball players [1–6]. Our experience at the 2012 Summer Olympic Games suggests that significant ligament and tendon injuries to the elbow can occur frequently in nonthrowing athletes, particularly in judo and weightlifting. Most of the elbow injuries seen in these athletes were isolated high-grade UCL injuries, although combinations of medial and lateral ligament injuries can occur. Ulnar attachment tears were the next most common injuries, followed by midsubstance tears of the UCL. This trend differs from the existing literature, which suggests that midsubstance tears are the most common type of UCL injuries [17, 27].

Acute elbow injuries in judo occurred during classic arm lock maneuvers, causing severe valgus stress and resulting in significant injury to the medial compartment. Weightlifting was the second most common sports category, after judo, in which athletes presented with acute elbow injuries with significant ligament tears. The mechanism of injury in weightlifting is axial loading with valgus strain on the hyperextended elbow. These injuries commonly occurred during overhead lift maneuvers, where the elbow in pronation and hyperextension was subjected to axial loading. In extreme cases, this resulted in frank dislocation of the elbow.

The other category of sport that presented with severe ligamentous injury to the elbow was overhead javelin throwing. These injuries were sustained during the late cocking and acceleration phase of the throw, during which maximal tensile strength is exerted on the elbow [1, 6].

Elbow injuries in Olympic sports have not been reported previously. The London 2012 Summer Olympic Games provided us with a unique opportunity to study the spectrum of imaging findings in a variety of Olympic sports and to correlate them with the mechanism of injuries. Our experience of imaging at the Olympics shows that elbow injuries are not infrequent, with most occurring in power and combat sports, including judo, boxing, wrestling, and weightlifting.

Most of the injuries resulted from valgus strain with hyperextension of the elbow and usually presented as injuries to the medial joint supporting structures. Combinations of medial and lateral ligaments were seen in combat and power sports with high-energy acute trauma. Such injuries also resulted in tears to secondary stabilizers of the medial joint, including the common flexor tendons and medial muscular compartments.

In summary, imaging modalities, particularly MRI and ultrasound, were complementary and contributed substantially to the games' imaging program. We think that there remains scope for studying the biomechanics of elbow injuries in nonthrowing athletes, and international sporting events such as Summer Olympics provide an ideal platform for further studies.