Imaging of Sports Injuries of the 183

Imaging of Sports Injuries of the Elbow 12

Milko C. de Jonge and Mario Maas

CONTENTS 12.1 Introduction 12.1 Introduction 183 Elbow injuries in athletes are relatively uncommon. 12.2 Anatomy 185 Particularly, acute traumatic elbow injuries, result- ing in fractures, dislocations or musculotendineous 12.3 Biomechanics 186 Gerbino 12.3.1 Introduction 186 structures are rarely seen ( 2003) (Fig. 12.1). 12.3.2 Baseball (and Other Overhead Throwing They are summarized in Table 12.1. Most injuries and Sports) 186 complaints of pain can be attributed to chronic over- 12.3.3 Tennis 186 use injuries. Sports activities that are prone to elbow 12.3.4 Golf 186 12.3.5 Handball and Soccer injuries involve those with extensive use of the (European Football) 187 in throwing (e.g., baseball pitching, javelin), those in 12.3.6 Gymnastics 187 which the arm is used as a lever with swinging and/or hitting (e.g., golf, tennis, racquetball) and those in 12.4 Imaging the Elbow 187 which the arm is turned into a weight bearing 12.4.1 Introduction 187 12.4.2 Baseball and Overhead Throwing Sports 188 12.4.2.1 Standard Radiographs 188 12.4.2.2 Ultrasound 189 12.4.2.3 CT 189 12.4.2.4 MRI 190 12.4.3 Golf 191 12.4.3.1 Standard 191 12.4.3.2 Ultrasound 191 12.4.3.3 MRI 191 12.4.4 Tennis 192 12.4.4.1 Standard Radiography 192 12.4.4.2 Ultrasound 192 12.4.4.3 MRI 193 12.4.5 Handball and Soccer 194 12.4.5.1 Standard Radiography 194 12.4.5.2 Ultrasound 194 12.4.5.3 MRI 194 12.4.5.4 CT 194 Fig. 12.1. A 23-year-old female gymnast sustained a fall on the 12.4.6 Gymnastics 195 left elbow while training on the balance beam. Axial T2-WI 12.4.6.1 Standard Radiography 195 FS image of the left elbow at the level of the tuberositas radii. 12.4.6.2 Ultrasound 196 Extensive muscle edema and partial rupture of the pronator 12.4.6.3 MRI 196 teres muscle (asterisk), muscle edema in the superfi cial fl exor 12.4.6.4 CT 197 digitorum muscle (arrow) and extensive fl uid in the fascial planes and subcutaneously 12.5 Conclusions 198

Things to Remember 198 M. C. de Jonge, MD References 198 M. Maas MD, PhD Dept. of Radiology, Academic Medical Centre, PO Box 22660, Suite G1-210, 1105 AZ Amsterdam, The Netherlands 184 M. C. de Jonge and M. Maas

Table 12.1. Classic traumatologic injuries of the elbow Box 12.1. Standard radiography Adult Child/adolescent ● Initial survey, especially in acute injuries Fracture/dislocation Fracture/dislocation ● Evaluation of osseous structures, avulsion inju- - Radial head/ fracture - Radial head dislocation ries and calcifi cations - Olecranon fracture (‚pulled elbow‘) - Elbow dislocation - Supracondylar ● Cheap and fast - Posterior fracture ● AP and Lateral views will usually suffi ce - Anterior (less common) - Elbow dislocation - Supracondylar humerus - Posterior ● Reversed axial projection and stress views can Fracture - Anterior (rare) be helpful - Coronoid process fracture - Epicondyle fracture - Epicondyle fracture (rare) - Galleazzi/Monteggia - Galleazzi/Monteggia Frac- fracture-dislocation ture-dislocation (rare) - Radial head and ole- Box 12.2. Ultrasound cranon fractures (rare)

● Evaluation of soft tissues Soft tissue injury Soft tissue injury

● Higher sensitivity for avulsions and calcifi ca- - Distal biceps tendon rupture Rare tions compared to MRI - Triceps tendon rupture ● Very high spatial resolution compared to MRI

● Available and cheap (e.g., gymnastics, weightlifting). In addition sports activities in which the arm is used to block goal fi red ● Detection of loose intra-articular bodies best shots are prone to elbow injuries (e.g., goalkeepers in with joint effusion handball and soccer). There are several factors that contribute to injuries of the elbow in sports activities. They can basically be Box 12.3. MRI divided into intrinsic and extrinsic factors (Wilder Sethi Gissane ● Evaluation of soft tissues and osseous structures and 2004; et al. 2001). Intrinsic fac- tors are athlete related, such as joint stability, muscle ● Superior contrast resolution compared to US strength, skeletal maturity and history of previous injuries. Extrinsic factors are sports related such as ● Low sensitivity for small avulsions and biomechanics of the game, equipment used, training calcifi cations hours and coaching. Particularly game biomechan- ● Diffi cult especially in painful lesions ics seems to be the most important extrinsic factor. In overhead throwing athletes the amount of valgus ● Low sensitivity for intra-articular loose bodies stress at the elbow is signifi cant even in adequately in absence of joint effusion trained, non-injured, professional athletes with proper throwing techniques (Fleisig et al. 1995; Loftice et al. 2004; Werner et al. 2002). These forces Box 12.4. CT are inherent to the movements the arm makes to accelerate balls. Knowledge of specifi c game dynam- ● Evaluation of predominantly osseous structures ics is a prerequisite for a thorough understanding of ● High sensitivity for avulsions, calcifi cations specifi c sports related elbow lesions. and intra-articular loose bodies This chapter aims to give an overview of the dynamics of the most frequent sports related injuries ● Available and short examination time of the elbow (Table 12.2). The merits of the different imaging modalities (standard radiography, ultra- ● High radiation dose sound, computed tomography and magnetic reso- ● Often complementary to MRI nance imaging) in the diagnostic algorithm will be emphasized and are summarized in Boxes 12.1–12.4. Imaging of Sports Injuries of the Elbow 185

Table 12.2. Common injuries in selected sports

Sport Injury Common name

Baseball Ulnar collateral „Pitchers elbow“ Baseball - child/adolescent Medial epicondyle apophysitis „Little League elbow“ Tennis Lateral epicondylitis „Tennis elbow“ Golf Medial Epicondylitis „Golfers elbow“ Handball and soccer Intra-articular loose bodies „Goalkeepers elbow“ Gymnastics Osteochondral lesions -

12.2 Anatomy

The elbow has a central position in the - hand kinetic chain. It consists of three articulations joined in a common synovial compartment known as the humero-ulnar, the capitello-radial and the (proximal) radio-ulnar joint. To allow a combination of fl exion-extension (humero-ulnar), pro- supination (radio-ulnar) and stability of the elbow joint, a spe- cifi c congruent design of the humero-ulnar articular surfaces is needed. A triangular shaped fortifi cation of the medial capsular structures is the medial or ulnar collateral ligament (UCL), the origin or top of the triangle is located at the medial epicondyle and the broad base is located at the ulna (anterior to the pro- cessus coronoideus and posterior to the olecranon). On the lateral side a capsular fortifi cation arises from the lateral epicondyle and forms the radial ligamen- tous complex (RLC) (Alcid et al. 2004; Kijowski et al. 2004). The UCL consists of three separate struc- Fig. 12.2. Normal anatomy of the ulnar collateral liga- tures, the anterior bundle, the posterior bundle and ment. It consists of three separate bundles: the anterior the transverse bundle (Fig. 12.2). The anterior bundle bundle (black arrow), the posterior bundle (white arrow) is the most important valgus stress stabilizer of the and the transverse bundle (arrowhead). Reprinted with Kijowski elbow joint, and can be further divided into ante- permission from et al. (2004) rior and posterior bands that alternate in tautness in extended and fl exed position, respectively. Since the transverse bundle does not cross the elbow joint itself it does not contribute much to the stability (Alcid ulna anterior and the radial head. The most important et al. 2004; Chung and Kim 2003; Kijowski et al. musculotendinous structures are, arising from the lat- 2004; Thornton et al. 2003). The RLC is composed eral epicondyle, the common extensor tendon includ- of four different and protects the elbow ing the lower arm, hand and wrist extensors, and the against varus stress and posterolateral instability. It common fl exor tendon or pronator-fl exor complex is much less prone to injury than the UCL (Alcid et which arises from the medial epicondyle (Alcid et al. al. 2004; Chung and Kim 2003; Kijowski et al. 2004; 2004). The ulnar nerve, which is the most often com- Thornton et al. 2003). The most important osseous promised nerve around the elbow in athletes, runs in landmarks are the medial and lateral epicondyle of the a fi bro-osseous groove at the medial humeral epicon- humerus, the olecranon, the coronoid process of the dyle, close to the origin of the UCL (Fig. 12.10). 186 M. C. de Jonge and M. Maas

lesions) (Bojanic et al. 2005; Cain et al. 2003; Gerbino 12.3 2003; Loftice et al. 2004; Kijowski et al. 2004). Biomechanics The term ‘”little league elbow” usually refers to athletic injuries in the immature skeleton, probably 12.3.1 due to improper throwing techniques. Originally Introduction described as a medial epicondyle fracture (Brogdon and Crow 1960), the term is actually reserved to Biomechanically the elbow joint acts as a combination describe medial epicondyle traction apophysitis or of a hinge joint (ulno-humeral and radio-humeral) medial apophyseal avulsion. and a more pivot joint (radio-humeral and proximal Although javelin and American football involve radio-ulnar) allowing not only fl exion-extension but overhead throwing similar to the baseball pitch, inju- also pronation-supination movements. The main sta- ries to the elbow are much less frequent. It is suggested bility of the elbow results from the highly congruent that in football this is probably due to lower forces and ulno-humeral joint surfaces and the collateral liga- less torque in the elbow during the throw (Loftice ments, preventing hyperextension and hyperfl exion, et al. 2004). Although several studies have been pub- and varus and valgus, respectively (Alcid et al. 2004; lished on the specifi c biomechanics of the throw in jav- Loftice et al. 2004). elin (which also involves powerful fl exion from maxi- mal extended position) (Bartlett and Rent 1988; Morris and Bartlett 1996), there is lack of large 12.3.2 studies on elbow injuries in this sports discipline. Baseball (and Other Overhead Throwing Sports)

In baseball, elbow injuries most commonly originate 12.3.3 due to pitching, hence the term “pitcher’s elbow” which Tennis actually most often refers to an injury of the UCL. The pitch, a very complicated movement, is com- “Tennis elbow” or lateral epicondylitis is associated monly divided into six phases: windup, stride, cocking, with excessive overuse of the hand and wrist extensor acceleration, deceleration and follow through (Alcid muscles (Loftice et al. 2004; Roetert et al. 1995). et al. 2004; Fleisig et al. 1995; Loftice et al. 2004; The tendon most commonly involved is the exten- Werner et al. 1993, 2002). These different phases are sor carpi radialis brevis (ECRB) (Levin et al. 2005; well described in the literature and apply more or less Miller et al. 2002; Roetert et al. 1995). Injuries seem to other overhead throwing athletes. Essentially, the to be predominantly associated with improper back- elbow moves during these phases from a fl exed to an hand use, leading to excessive forces at the level of the extended position, The greatest forces occur during common extensor origin. Despite the fact that studies the cocking and acceleration phases when maximum have shown that in all major strokes at tennis the wrist valgus and extension forces are applied to the UCL that extensors are highly involved, only improper back- acts as the primary valgus stabilizer (Loftice et al. hand use is predominantly associated with tendinosis 2004; Werner et al. 1993; Chen et al. 2001). This can and paratenonitis of the origin of the ECRB (Loftice result in acute and chronic injuries of the UCL and/or et al. 2004; Roetert et al. 1995). Other factors that the pronator-fl exor complex that acts as the secondary have been incriminated consist of improper hand/ medial stabilizing structure (Alcid et al. 2004; Cain et wrist positioning (over-pronation and hyperfl exion), al. 2003; Chen et al. 2001). The stability of the osteo- eccentric location of impact of the ball on the racket chondral structure itself, more specifi cally the olecra- and the amount of force impact/transfer from the ball non in the fossa olecrani and the radio-capitellar joint, to the racket (Roetert et al. 1995). increases when the elbow moves towards extension leading to torque forces and shearing of the olecra- non in its fossa and to posterior osteophyte formation 12.3.4 resulting in what is called “valgus extension overload Golf syndrome” (VEO) (Ahmad and ElAttrache 2004). The compressive forces that are generated in the lateral For a non-throwing sport, golf places enormous strains elbow can lead to cartilage damage or bone lesions of on the different components of the kinetic shoulder- the radial head and/or capitellum (e.g., osteochondral elbow-wrist chain. An injury to the elbow in golfers is Imaging of Sports Injuries of the Elbow 187 almost always swing related or due to improper tech- ticular risk for injuries to the growing skeleton which nique. Whereas the backswing is relatively harmless are different compared to injury patterns encoun- for the elbow, it is the downswing and impact which tered in adults. Osteochondral lesions are frequently causes the problems (Loftice et al. 2004; McCarrol seen in gymnasts, because they use their elbow as a 2001). The medial epicondylitis or so called “golfer’s weight bearing joint (Bojanic et al. 2005; Jackson et elbow”, is an overuse injury of the common pronator- al. 1989). It is predominantly an overuse injury caused fl exor origin and occurs typically in the elbow of the by repetitive microtrauma to the immature cartilage. dominant arm (the right arm in a right-handed golf A similar pattern is seen in weightlifters. player). Not only improper technique contributes bio- mechanically but also abrupt trauma when the player hits the ground in front of or behind the ball. It is the violent deceleration on impact that strains the medial compartment, and that raises forceful contractions at 12.4 the medial and lateral lower arm musculature to stabi- Imaging the Elbow lize the elbow and the club that lead to the condition (McCarrol 2001; Thériault and Lachance 1998). 12.4.1 Therefore, lateral epicondylitis is also a common Introduction problem at the non-dominant arm or lead arm in golf players (Loftice et al. 2004; McCarrol 1996; In the authors opinion, standard radiography should McCarrol 2001; Thériault and Lachance 1998). be the fi rst imaging modality of choice. Apart from Forceful overuse of the common extensor muscles a so-called reversed axial projection which allows leading to lateral epicondylitis is more frequent when better visualisation of the olecranon and the trochlea the grip of the golf club is too tight. The frequency of (Fig. 12.3), additional views in many different direc- medial and lateral injuries is more or less equal in golf tions are usually not helpful. The value of stress players (McCarrol 1996). radiographs is discussed elsewhere. Ultrasound is a fast and cheap way to evaluate the elbow. To study the anterior recess the arm is 12.3.5 partially fl exed and supinated while the posterior Handball and Soccer (European Football) recess is best evaluated in elbow extension. Lateral and medial visualisation is optimal in extension or Although biomechanically there is a great difference 90q fl exion semi-pronated or a slightly fl exed elbow between handball and soccer players, with regards to exorotated, respectively. The posterior elbow soft elbow injuries the goalkeeper’s in both sports share tissues are most easily examined in fl exion with the a common injury pattern of the elbow, which is palm of the hand fl at on the table (fi ngers directed called the “goalkeeper’s elbow”. Two mechanisms are towards patient) (Ferrara and Marcelis 1997). involved: the fi rst is the injury pattern as seen in many In MRI the positioning of the elbow is considered overhead throwing athletes. Therefore, similar elbow to be one of the most important factors which can be lesions as in overhead throwing athletes are found either fully supinated and extended (besides supine (Popovic and Lemaire 2002; Popovic et al. 2001). body) or in an overhead pronated and extended posi- The second (which is more typical for goalkeepers) tion (body prone) (‘Superman’s position’) in which is repeated hyperextension of the elbow due to the case the elbow is more in the center of the magnet blockage of shots fi red at the goal. This hyperexten- which improves image quality. All imaging planes can sion trauma leads to repetitive abutment of the olec- be useful but one has to make sure that the coronal ranon in its fossa leading to cartilage damage, osteo- plane is parallel to the middle of both humeral con- phyte formation and intra-articular loose bodies. dyles (Fig. 12.4), although a coronal oblique plane is also proposed, especially for the collateral ligaments (Cotten et al. 1997). The role of MR arthrography is 12.3.6 controversial, but there is no evidence that routinely Gymnastics MR-arthrography is more accurate than conventional MRI. Participants in gymnastics are traditionally and Helical High Resolution CT (HRCT) with 0.6 or increasingly younger in age. This puts them at a par- 0.5 mm slice thickness can have its advantages over 188 M. C. de Jonge and M. Maas

Fig. 12.3. Reversed axial projection of the right elbow allows better visualization of the posterior elbow, in particular the olecranon and the posterior part of the humero-ulnar joint

12.4.2 Baseball and Overhead Throwing Sports

12.4.2.1 Standard Radiographs

Standard radiographs of the elbow, in case of suspi- cion of UCL injury, aims to exclude small avulsions at its proximal attachment at the medial epicondyle of the humerus (Fig. 12.5) or at its distal insertion at the sublime tubercle, which is the medial aspect of the coronoid process of the ulna. Osteophytes are more diffi cult to appreciate, for these are most common at the postero-medial olecranon in case of chronic UCL injury or “valgus extension overload syndrome”. There are several studies that describe the value of Fig. 12.4. Coronal MRI (or CT MPR) plane is planned on an stress radiography of the elbow in which AP views of axial image and runs parallel to the condyles of the distal the elbow are made while valgus stress is applied to the humerus elbow (Lee et al. 1998; Rijke et al. 1994; Eygendaal et al. 2000). Rijke et al. (1994) differentiates partial MRI due to the superior spatial resolution in which (grade 2) from complete (grade 3) UCL tears using the osseous structures are visualized. Examining the this technique. Lee et al. (1998) recognized the value elbow with HRCT takes a considerable shorter time of stress radiography in valgus instability, with com- compared to a MRI investigation which can be of sig- parative views of the uninjured elbow to differentiate nifi cant importance in a painful patient. instability from non-traumatic joint laxity. The role of bone scintigraphy is declining since the Medial apophysitis, in skeletally immature throw- introduction of MRI. It is not the high sensitivity of ers, may produce subtle abnormalities on plain fi lms. scintigraphy for bony abnormalities but the low spec- Slight widening of the apophysis or fragmentation of ifi city and blindness to soft tissue lesions that limits the ossifi cation centre can be seen (Chen et al. 2005; its use (Va n d e r wa l et al. 2001). Hang et al. 2004; Klingele and Kocher 2002). Imaging of Sports Injuries of the Elbow 189

Fig. 12.6. Longitudinal ultrasound view of a normal UCL (arrowheads). The normal UCL is hyperechoic and has a fan- like shape proximally. Distally its insertion is at the sublime tubercle of the proximal ulna (arrow)

Fig. 12.5. A 20-year-old baseball player with pain Jacobson in the region of the UCL for several months. AP the ligament). et al. (2003) described in a radiograph of the left arm. A faint calcifi cation is very small population the variable appearance of the seen at the region of the proximal attachment of proximal part of the UCL. Nazarian et al. (2003) the UCL (arrow) reported on dynamic US of the anterior band of the UCL in which he looked at the UCL and the width of the ulnohumeral joint with valgus stress, which is 12.4.2.2 an ultrasonographic equivalent to the valgus stress Ultrasound radiography. They concluded that in pitching the anterior band of the UCL is thicker and con- The role of ultrasound in the evaluation of UCL injury tains statistically signifi cant more calcifi cations and remains unclear; it has been discussed in only a few hypo-echoic foci. In addition, as we know from stress papers (De Smet et al. 2002; Jacobson et al. 2003; radiographs, they found an increase in width of the Miller et al. 2004; Nazarian et al. 2003; Wa r d et ulnohumeral joint when valgus stress was applied. al. 2003). Although the possibility of US identifi ca- Although populations in these studies are small it is tion of the UCL is well demonstrated on cadavers likely that US can play a role in the evaluation of the and/or compared with MRI, there are no large studies anterior bundle of the UCL. including US, clinical fi ndings and/or MRI in athletes. Wa r d et al. (2003) described the ultrasonographic 12.4.2.3 appearance of the UCL and correlated these fi ndings CT in cadavers. Baseline parameters for the evaluation of the ligament were defi ned that may be helpful to The use of CT as a secondary imaging modality (after determine injured from non-injured ligaments. The standard radiography) to evaluate elbow injuries in normal anterior bundle of the UCL is hyperechoic overhead throwing athletes is almost exclusively (compared to surrounding muscle) with a fi brillar reserved for acute bony trauma (fractures). Chronic pattern and a fanlike shape (Fig. 12.6). Miller et osseous injuries like stress fractures of the olecranon al. (2004) studied the UCL using US in eight base- are relatively uncommon in overhead throwers but ball pitchers with clinical suspicion of UCL injury. have been described in baseball players and javelin Although the US fi ndings were only confi rmed with throwers and can be visualized with CT, especially the MRI in six patients and with surgery in three patients type III and IV fractures (classifi cation by Arendt/ they described the abnormalities that can be seen Griffi ths) (Iwamoto and Takeda 2003; Arendt and in UCL, e.g., non-visualization of the ligament or Griffi ths 1997). If, on standard radiographs, a bony alterations in morphology (hypo-echoic areas within avulsion is suspected in case of an UCL injury, CT will 190 M. C. de Jonge and M. Maas

yield better results than MRI in describing the exact size and location of the fragment (Fig. 12.7). In case of “valgus extension overload syndrome”, CT can depict the exact size and location of the osteophytes at the posterior olecranon better than standard radiogra- phy. An additional advantage of CT is that in case of absence of intra-articular fl uid an intra-articular osseous loose fragment will be picked up more easily than with MRI.

Fig. 12.8. Normal left elbow. Coronal T1-WI. The ulnar collateral ligament (arrowheads) has a normal thin appearance, it is sharply outlined and of overall low signal intensity. There is a relatively broad origin below the undersurface of the medial epicondyle which is considered normal. The faint hyperintense appearance of the ligament in this area is probably due to interspersed fat

Fig. 12.7. Coronal CT MPR of the same patient as in Fig. 12.5. A small avulsion at the origin of the UCL is very well appreciated on CT (arrow)

12.4.2.4 MRI

The anterior bundle of the UCL is the most impor- tant structure to visualize in an overhead throwing athlete with medial elbow pain. It is the only part of the medial complex that is seen in the coronal plane in which it should appear as a thin continuous linear structure with a low signal intensity on all sequences (Kijowski et al. 2005) (Fig. 12.8). A small amount of fat can be seen deep and/or superfi cial to the ligament (Jacobson et al. 2003). Complete rupture is demon- Fig. 12.9. An 18-year-old baseball pitcher with strated through non-visualization of the ligament or chronic ulnar sided elbow pain. Coronal T2*- weighted image. There is a complete disruption focal complete disruption at the ulnar or humeral of the origin of the UCL at the level of the medial attachment (Fig. 12.9). Other signs of rupture, either epicondyle (arrow) with fl uid surrounding the partial or compete, includes laxity, thickening, irregu- ligament that is slackened, somewhat irregular larities and poor defi nition of the ligament as well and blurred Imaging of Sports Injuries of the Elbow 191 as abnormal signal intensity in or around the liga- (Cain et al. 2003; Field and Savoie 1998; Gerbino ment (Kijowski et al. 2005; Nakanishi et al. 1996; 2003; Kijowski et al. 2005; Thornton et al. 2003). Sonin and Fitzgerald 1996; Thornton et al. 2003). In the immature skeleton the apophysis of the Complete ruptures are easier to diagnose than partial medial epicondyle is particularly vulnerable to repet- ruptures. A sensitivity and specifi city of as high as itive stress (Klingele and Kocker. 2002). The role 100% has been described for complete ruptures, for of MRI in the evaluation of little league elbow is still partial rupture a sensitivity of only 57% is reported unclear. The epiphyseal growth plate usually has high (Timmerman et al. 1994). Partial ruptures are more signal intensity on T2-weighted and STIR images easily seen if surrounded by fl uid. This explains the which makes the differentiation with bone marrow preference of some radiologists to perform MR- edema not obvious. This is also true if there is frag- arthrography in which there is extravasation of mentation of the apophysis which is better seen on fl uid or gadolinium extra-articular into or beyond plain radiographs. the ligament (Munshi et al. 2004; Nakanishi et al. 1996; Timmerman et al. 1994; Thornton et al. 2003). Whatever technique used, we have to be careful in 12.4.3 diagnosing partial tears since several studies showed Golf that the UCL can have a variable appearance not only at its distal insertion at the sublime tubercle but also 12.4.3.1 at its proximal attachment at the humeral epicondyle Standard Radiography (Jacobson et al. 2003; Munshi et al. 2004). In “valgus extension overload syndrome” MRI is Standard radiography is of little value in golfer’s used to evaluate the UCL, the joint cartilage and the elbow. Nonspecifi c fi ndings such as soft tissue swell- olecranon to look for osteophytes and loose bodies. ing, loss of normal fat planes adjacent to the medial The UCL is expected to be thickened and irregular epicondyle, small calcifi cations or subtle cortical and predominantly hypo-intense on T1-weighted irregularities at the origin of the common fl exor and T2-weighted sequences refl ecting fi brosis as part tendon, can be seen (Chen et al. 2003; Kijowski et of repair of microtears. Bone marrow edema can be al. 2005). A bony avulsed fragment at the common seen in the olecranon representing repetitive bony fl exor tendon origin or the UCL is another possible stress. Particular attention has to be paid to the ulnar fi nding. nerve since ulnar neuropathy can accompany VEO syndrome (Fig. 12.10). The ulnar nerve may be thick- 12.4.3.2 ened with high signal intensity on PD or T2-weighted Ultrasound images and/or can be subluxed from the ulnar groove Ultrasound is the imaging modality of choice in medial epicondylitis. The common fl exor tendon will be thickened and irregularly delineated with a heterogeneous echoarchitecture. Linear hypo-echoic intratendinous fi ssures or small calcifi cations can be seen. Moreover, fl uid can be identifi ed at the extra- articular aspect of the UCL as well as focal synovi- tis at the medial aspect of the joint (Ferrara and Marcelis 1997). Interindividual variability with a short common fl exor tendon makes ultrasonographic evaluation more diffi cult. In these cases, comparison with the uninjured arm is then useful.

12.4.3.3 MRI

Fig. 12.10. Transverse US image of the elbow showing the UCL MRI in medial epicondylitis can reveal a spectrum (arrows). Note the close proximity of the ulnar nerve (arrow- of abnormalities depending upon the duration and heads) which is often compromised in cases of UCL injuries severity of the symptoms. The more acute phase 192 M. C. de Jonge and M. Maas

of tendinosis with paratenonitis is characterized by increased signal respectively in and around the tendon on T1 and T2-WI as well as on STIR images (Kijowski et al. 2005). This increased signal can vary between faint hyperintensity on fl uid-sensitive sequences to areas with frank fl uid signal. Thicken- ing of the tendon can be seen in more chronic cases, which will most often be referred to as tendinosis. Although tendinosis and tendinitis are confusingly interchangeably used in the literature to describe overuse and degenerative pathology, the correct terminology from the histopathological point of view is tendinosis. Intratendinous infl ammation is not predominantly present on pathological speci- mens. Infl ammatory infi ltration may be present at the tendon sheath or paratenon and thus is referred to as tenovaginitis and paratenonitis, respectively. It is obvious that only the “-itis” disorders respond to anti-infl ammatory drugs (Khan et al. 1999; Puddu et al. 1976). In case of a rupture of the common fl exor Fig. 12.11. Patient with chronic lateral epicondy- tendon, thinning or disruption with a fl uid fi lled litis. AP radiograph showing calcifi cations at the gap at the level of the tear is seen (Thornton et al. level of the insertion of the common extensor 2003). Bone marrow edema in the medial epicondyle tendon (arrow) and in the surrounding muscles has been described (Thornton et al. 2003). Abnormalities are most frequent at the fl exor carpi radialis and pronator teres part of the common fl exor tendon (Kijowski et al. 2005; Thornton et al. 2003). The ulnar nerve is compromised in up to 60% of patients (Jobe and Cicotti 1994); neuritis will show thickening of the ulnar nerve with an increased signal on T2-weighted images in the nerve and the surrounding tissues.

12.4.4 Tennis

12.4.4.1 Standard Radiography Fig. 12.12. Longitudinal US view of the normal common exten- sor tendon origin (arrow). Radial head (asterisk) Findings on standard radiology in cases of “tennis elbow” or lateral epicondylitis are similar to those seen in cases of medial epicondylitis, conventional include: linear intrasubstance tears, thickening of fi lms in both conditions will usually be normal or the tendon, calcifi cations as well as enthesophytes, not relevant (Fig. 12.11). bone irregularities, focal hypo-echoic areas, peri- tendinous fl uid and diffuse tendon heterogeneity 12.4.4.2 (Connell et al. 2001; Levin et al. 2005; Miller et Ultrasound al. 2002) (Fig. 12.13). Studies by Levin et al. (2005) and Miller et al. (2002) showed a good US sensitiv- The ultrasound appearance of the common exten- ity for lateral epicondylitis ranging from 64% to 88% sor tendinosis (Fig. 12.12) is basically similar to the but relatively poor specifi city, compared to a better fi ndings in common fl exor tendon overuse. They sensitivity and specifi city by MRI of 90%–100% and Imaging of Sports Injuries of the Elbow 193

ligament are not uncommon in patients with lateral epicondylitis (Bredella et al. 1999). Bone marrow edema at the lateral humeral epicondyle can occur (Martin and Schweitzer 1998) as well as T2- weighted hyperintense signal in the surrounding soft tissues (e.g., anconeus muscle) (Coel et al. 1993).

Fig. 12.13. A 26-year-old tennis player with longstanding pain at the lateral epicondyle. Longitudinal US view of the common extensor tendon. A severe tendinosis with a thickened inho- mogeneous appearance of the tendon (arrowheads) is demon- strated. There is fl uid in the joint extending between the origin of the tendon and the humerus (long white arrow). A calcifi ca- tion is seen (short white arrow). Radial head (asterisk)

83%–100%, respectively. The value of power Doppler application in the evaluation of the common extensor and fl exor tendon and paratenon at the elbow has not been studied yet.

12.4.4.3 a MRI

A very high sensitivity is repeatedly reported for MRI in the evaluation of lateral epicondylitis, although a meta-analysis in 2001 concluded that the assessment of MRI fi ndings in epicondylitis is questionable due to small sample sizes and methodological shortcomings (Pasternack et al. 2001). Fluid sensitive sequences are mandatory (STIR or T2-Fat Sat); the axial and coronal planes are the most helpful in the evaluation of the common extensor tendon. The ECRB is most often involved, not rarely with secondary involve- ment of the extensor digitorum communis (EDC) (Nirschl 1992). Findings depend upon chronicity of the condition and are thickening or thinning of the tendon and increased signal on the fl uid sen- b sitive sequences and/or the T1-weighted sequences (Fig. 12.14). These fi ndings can however also be Fig. 12.14a,b. A 30-year-old tennis player with clinically lat- found in non-symptomatic high-performance ath- eral epicondylitis on the right side. Oblique coronal STIR (a) letes (Martin and Schweitzer 1998). Furthermore, (imaging plane represented by white line in image b) and axial PD-MR image of the right elbow (b). There is hyperintense the radiologist has to be informed if any treatment signal in and around the common extensor tendon (white has been applied (e.g., local corticosteroid injection, arrow), fl uid in the joint (arrowhead in a) and irregular and shock wave therapy, etc.) prior to MRI. In the coronal non-homogeneous tendon (black arrow). There is accompany- plane the RLC is assessed because injuries to this ing anconeus tendinopathy (arrowhead in b) 194 M. C. de Jonge and M. Maas

12.4.5 12.4.5.2 Handball and Soccer Ultrasound

12.4.5.1 US is useful in the detection of loose bodies in the Standard Radiography elbow joint (Popovic and Lemaire 2002; Popovic et al. 2001; Ferrara and Marcelis 1997). This is Although not commonly demonstrated the main especially true if there is an associated joint effusion indication for standard radiography in “goalkeepers which is often present due to secondary synovitis. elbow” are intra-articular loose bodies. There are no Calcifi ed loose intra-articular bodies present as focal studies describing the accuracy of plain fi lms for the echogenic structures separate from cortical bone, the detection of loose bodies in the elbow joint. Particu- larger one’s with posterior shadowing. Loose bodies lar attention has to be paid to the olecranon fossa and as small as 1 mm can be detected especially in the the anterior aspect of the elbow near the coronoid presence of joint effusion (Marcelis et al. 1996). The process of the ulna (Fig. 12.15). Sometimes a reverse most common locations include the olecranon fossa axial projection can be helpful to better evaluate the and the coronoid fossa (O’Driscoll 1992). posterior elbow (Chen et al. 2003). Physiologic and pathologic thickening of the vari- In handball and baseball players a generalized ous tendons surrounding the elbow joint is described bony hypertrophy of the humerus of the dominant in handball goalkeepers (Popovic et al. 2001). arm is reported. This is manifested by an increased humeral diameter and cortical hypertrophy of the 12.4.5.3 humeral shaft, regardless of any complaints ( Popovic MRI et al. 2001; Gore et al. 1980). Stress radiography usu- ally reveals laxity of the medial elbow structures MRI can be used to detect intra-articular loose (as in baseball players) demonstrated as increase in bodies especially when there is an associated effu- ulno-humeral distance if valgus stress is applied to sion (Quinn et al. 1994). The signal intensity is vari- the elbow (Popovic and Lemaire 2002; Popovic et able depending upon the amount of calcifi cation and al. 2001). bone marrow if ossifi cation is present. Particularly T2-weighted and gradient echo sequences are useful to detect loose bodies, the latter sequence can also be particularly helpful to evaluate a potential donor site, e.g., chondral defects. In the absence of an effusion the accuracy of MRI is far less with a sensitivity of 50% and a specifi city of 60% (Miller 1999). In these cases, injection of saline or gadolinium into the joint improves accuracy but one has to be careful not to inject air bubbles into the joint for these can easily be mistaken for loose bodies. Osteophytes and synovial proliferations can be mistaken for loose bodies.

12.4.5.4 CT

In the authors opinion, CT of the elbow is superior to Fig. 12.15. Professional 28-year-old soccer goalkeeper with MRI and US in the detection of calcifi ed loose bodies recurrent right elbow pain. Lateral radiograph of the right but also for the detection of osteophytes. Our high elbow. A small ossicle is seen in the fossa olecrani (arrow) resolution CT (HRCT) protocol includes axial plane which can represent an accessory ossicle or intraarticular imaging with 0.5 or 0.6 mm slice thickness and two- loose body. No other loose bodies are identifi ed dimensional multi planar reformatting in any desired plane. The position of the elbow is relatively unim- portant and can range form fully supine to fully prone. Even in the absence of fl uid, the small calcifi cations can be detected in any part of the joint (Fig. 12.16). Imaging of Sports Injuries of the Elbow 195

age of the lesion (Fig. 12.17). Subtle irregularities of the subchondral bone lamella may precede fl attening of the contour of the involved bone. A ‘displaced fat pad’ sign results from joint effusion, loose bodies may be identifi ed. A distinction has to be made between osteochondral lesions (osteochondritis dissecans, OD) and Panner’s disease, which is not always easy. The latter is considered to be an osteochondrosis of the capitellum. It is most common in young prepubes- cent males. On radiographs the entire capitellum can be involved with sclerosis, irregularities and lucencies. It is however, a benign self-limiting disorder in which the capitellum will regain a normal appearance.

Fig. 12.16. Same patient as in Fig. 12.15. MDCT MRP recon- structions in the axial and coronal plane demonstrating mul- tiple small intra-articular loose bodies (arrows) in the right elbow joint which are not appreciated on plain fi lms

The cartilage layer itself cannot be evaluated without intra-articular iodine contrast, but for the detection of osteochondral lesions CT probably has an accuracy as high as MRI, as is demonstrated in the joint (Verhagen et al. 2005). A potential pitfall is the pseu- dodefect of the capitellum (see Sect. 12.4.6.3).

12.4.6 Gymnastics

12.4.6.1 Standard Radiography

Osteochondral lesions in the elbow are for the most Fig. 12.17. A 15-year-old gymnast with right elbow pain. AP and lateral radiographs of the right elbow. On the lateral view part located at the capitellum most often anterior the lucency in the capitellum (arrowheads) is compatible with to central. The second most frequent location is the an osteochondral defect. The lesion is much more diffi cult to radial head. Usually a radiolucent area is seen sur- appreciate on the AP view, it is discriminated because of the rounded by more or less sclerosis depending upon the surrounding faint sclerosis (black arrows) 196 M. C. de Jonge and M. Maas

12.4.6.2 ferent signal intensity patterns (Bowen et al. 2001). Ultrasound The fi rst pattern consists of focal low signal inten- sity on T1-weighted images accompanied by high In cases of suspicion of osteochondral lesions ultra- signal intensity on corresponding T2-weighted sound is only helpful to detect joint effusion, intra- images. The second pattern is more complex with a articular loose bodies or other additional fi ndings focal intermediate signal intensity surrounded by a e.g., tendinosis or UCL injuries. low signal intensity ring on T1-weighted images, the innermost portion of the latter being high in signal 12.4.6.3 intensity on corresponding T2-weighted images MRI (Bowen et al. 2001). The clinical relevance of these different fi ndings is unknown. In advanced stages The MRI appearance of osteochondral lesions in the the lesion can appear of low SI on all sequences elbow joint varies. Different patterns are described. in case of a chronic (possible necrotic) fragment. Early OD may demonstrate focal low signal intensity Grading osteochondral lesions is not easy and the on T1-WI without changes on T2- or T2*-weighted clinical use of grading is uncertain. It is not clear sequences (Kijowski et al. 2004; Banks et al. 2005) whether grading or not changes treatment options (Fig. 12.18). Later on, lesions will display two dif- and outcome (Bowen et al. 2005). An “in situ”

Fig. 12.18a–c. A 10-year-old professional female gymnast with increasing pain at the left elbow for 3 months. Sagittal CT MPR image (a), coronal T1-weighted MR image (b) and sagittal gra- dient-echo T2*-WI MR image (c) of the left elbow. There is a small hypo-intense area at the capitellum slightly anterior (arrow in b) compatible with a very early osteochondral lesion. The corresponding cartilage image (c) shows no abnormali- ties to the overlying cartilage. On CT no loose fragments were seen. The early OD lesion is seen as a small area of sclerosis with intact cortex (arrow in a)

a

b c Imaging of Sports Injuries of the Elbow 197 dissecans fragment is considered unstable if it is lage itself cannot be assessed without intra-articular surrounded by fl uid like cysts or a complete T2- contrast. There is no literature on the role of CT weighted high signal intensity ring (De Smet et al. arthrography vs non-contrast CT or vs non-contrast 1996). On MR arthrography, the in situ fragments MRI. which are surrounded by contrast are considered unstable (Kramer et al. 1992). A pitfall in diagnosing OD lesions is the so-called pseudo-defect of the capitellum. This is found at the junction of the inferior capitellum with the poste- rior non articular surface of the lateral epicondyle (Rosenberg et al. 1994) (Fig. 12.19).

a

Fig. 12.19. Sagittal T2-weighted MR image of the elbow showing an irregular area (arrow) in the posterior capitellum compatible with a pseudo- defect

12.4.6.4 CT

Imaging of osteochondral lesions in the elbow is most often performed with MRI. There are no studies to compare CT and MRI in the detection of OD elbow. In the authors opinion CT is very useful for the detec- b tion of osteochondral lesions in either the capitel- lum or radial head provided HRCT is performed. Fig. 12.20a,b. A 16-year-old female gymnast with an Osteochondral lesions will present as (subtle) sub- osteochondral lesion of the radial head. Sagittal CT (a) and coronal gradient-echo T2*-WI MR image chondral bone lamella irregularities, subchondral (b) of the elbow. The OD lesion with the cortical cystic changes, subchondral density changes and/or defect (black arrow, a, white arrow, b) and the small defects at the subchondral lamella (Fig. 12.20). The loose fragments are better appreciated on the CT joint space width will usually be normal. The carti- than on the MRI 198 M. C. de Jonge and M. Maas

References 12.5 Conclusions Ahmad CS, ElAttrache NS (2004) Valgus extension overload syndrome and stress injury of the olecranon. Clin Sports Med 23:665–676 Elbow injuries in athletes are relatively uncommon, Alcid JG, Ahmad CS, Lee TQ (2004) Elbow anatomy and struc- especially acute injuries. Most injuries are contrib- tural biomechanics. Clin Sports Med 23:503–517 uted to overuse. Throwing, using the arm as a lever Arendt EA, Griffi ths HJ (1997) The use of MR imaging in the or as a weight bearing joint and stopping goal fi red assessment and clinical management of stress reactions of bone in high-performance athletes. Clin Sports Med shots are the mechanisms in which injuries most 16:291–306 often occur. Ulnar collateral ligament injuries, lateral Banks KP, Ly JQ, Beall DP et al. (2005) Overuse injuries of the and medial epicondylitis, medial epicondyle apophy- upper extremity in the competitive athlete: magnetic reso- sitis, osteochondral lesions and intraarticular loose nance imaging fi ndings associated with repetitive trauma. Curr Probl Diagn Radiol 34:127–142 bodies are the most common encountered injuries. Bartlett RM, Rent RJ (1988) The biomechanics of javelin Standard radiography should be the initial imag- throwing. J Sports Sci 6:1–38 ing modality but in general MRI is the most useful Bojanic I, Ivkovic A, Boric I (2005) Arthroscopy and micro imaging modality to use. In certain selected cases fracture technique in the treatment of osteochondritis dis- however US and CT can replace MRI or add valuable secans of the humeral capitellum: report of three adoles- cent gymnasts. Surg Sports Traumatol Arthrosc Oct information. 11; [Epub ahead of print] Bowen R, Otsuku N, Yoon S et al. (2001) Osteochondral lesions of the capitellum in pediatric patients: role of magnetic resonance imaging. J Pediatr Orthop 21:298–301 Bredella MA, Tirman PF, Fritz RC et al. (1999) MR imaging fi ndings of lateral ulnar collateral ligament abnormalities in patients with lateral epicondylitis. Am J Roentgenol 193: Things to Remember 1379–1382 Brogdon BG, Crow NE (1960) Little leaguer’s elbow. Am J 1. AP and lateral radiographs of the elbow are Roentgenol 83:671–675 usually suffi cient to evaluate the osseous Cain EL Jr, Dugas JR, Wolf RS et al. (2003) Elbow injuries in structures of the elbow. In selected cases throwing athletes: a current concepts review. Am J Sports Med 31:621–635 (valgus extension overload) a reversed axial Chen FS, Rokito AS, Jobe FW (2001) Medial elbow problems projection can be helpful. in the overhead-throwing athlete. J Am Acad Orthop Surg 9:99–113 2. Ultrasound has a very high sensitivity and Chen AL, Youm T, Ong BC et al. (2003) Imaging of the elbow specifi city to diagnose lateral and medial epi- in the overhead throwing athlete. Am J Sports Med 31:466– 473 condylitis and usually confi rms the diagnosis. Chen FS, Diaz VA, Loebenberg M et al. (2005) Shoulder and elbow injuries in the skeletally immature athlete. J Am Acad 3. In medial epicondylitis and ulnar collateral Orthop Surg 13:172–185 ligament injuries particular attention has to Chung CB, Kim HJ (2003) Sports injuries of the elbow. Magn be paid to the ulnar nerve which is often com- Reson Imaging Clin N Am 11:239–253 Coel M, Yamada CY, Ko J (1993) MR imaging of patients with promised in these conditions. lateral epicondylitis of the elbow (tennis elbow): impor- tance of increased signal of the anconeus muscle. Am J 4. Ulnar collateral ligament injuries are best Roentgenol 161:1019–1021 assessed using MRI. There is no evidence to Connell D, Burke F, Coombes P et al. (2001) Sonographic support that MR arthrography is superior to examination of lateral epicondylitis. Am J Roentgenol 176:777–782 non-enhanced MRI. Cotten A, Jacobson J, Brossmann J et al. (1997) Collateral liga- ments of the elbow: conventional MR imaging and MR 5. CT has a better sensitivity compared to MRI arthrography with coronal oblique plane and elbow fl ex- for intraarticular loose bodies especially in ion. Radiology 204:806–812 the absence of joint effusion. De Smet AA, Ilahi O, Graf B (1996) Reassessment of the MR criteria for the stability of osteochondritis dissecans in the knee and ankle. Skeletal Radiol 25:159–163 6. CT and MRI are comparable for demonstrat- De Smet AA, Winter TC, Best TM et al. (2002) Dynamic ing osteochondral lesions. sonography with valgus stress to assess elbow ulnar col- lateral ligament injury in baseball pitchers. Skeletal Radiol 31:671–676 Imaging of Sports Injuries of the Elbow 199

Eygendaal D, Heijboer MP, Obermann WR et al. (2000) Medial McCarroll JR (1996) The frequency of golf injuries. Clin Sports instability of the elbow. Findings on valgus load radiogra- Med 15:1–7 phy and MRI in 16 athletes. Acta Orthop Scand 71:480– McCarroll JR (2001) Overuse injuries of the upper extremity 483 in golf. Clin Sports Med 20:469–479 Ferrara MA, Marcelis S (1997) Continuing education – ultra- Miller TT (1999) Imaging of elbow disorders. Orthop Clin sound of the elbow. JBR-BTR 80:122–123 North Am 30:21–36 Field LD, Savoie FH (1998) Common elbow injuries in sport. Miller TT, Shapiro MA, Schultz E et al. (2002) Comparison of Sports Med 26:193–205 sonography and MRI for diagnosing epicondylitis. J Clin Fleisig GS, Andrews JR, Dillman CJ et al. (1995) Kinetics of Ultrasound 30:193–202 baseball pitching with implications about injury mecha- Miller TT, Adler RS, Friedman L (2004) Sonography of injury nisms. Am J Sports Med 23:233–239 of the ulnar collateral ligament of the elbow-initial experi- Gerbino PG (2003) Elbow disorders in throwing athletes. ence. Skeletal Radiol 33:386–391 Orthop Clin North Am 34:417–426 Morris C, Bartlett RM (1996) Biomechanical factors critical Gissane C, White J, Kerr K et al. (2001) An operational model for performance in the men’s javelin throw. Sports Med to investigate contact sports injuries. Med Sci Sports Exerc 21:438–446 33:1999–2003 Munshi M, Pretterklieber ML, Chung CB et al. (2004) Anterior Gore RM, Rogers LF, Bowerman J et al. (1980) Osseous mani- bundle of ulnar collateral ligament: evaluation of anatomic festations of elbow stress associated with sports activities. relationships by using MR imaging, MR arthrography, and Am J Roentgenol 134:971–977 gross anatomic and histologic analysis. Radiology 231:797– Hang DW, Chao CM, Hang YS (2004) A clinical and roentgen- 803 ographic study of Little League elbow. Am J Sports Med Nakanishi K, Masatomi T, Ochi T et al. (1996) MR arthrogra- 32:79–84 phy of elbow: evaluation of the ulnar collateral ligament of Iwamoto J, Takeda T (2003) Stress fractures in athletes; review elbow. Skeletal Radiol 25:629–634 of 196 cases. J Orthop Sci 8:273–278 Nazarian LN, McShane JM, Ciccotti MG et al. (2003) Dynamic Jackson DW, Silvino N, Reiman P (1989) Osteochondritis dis- US of the anterior band of the ulnar collateral ligament of secans in the female gymnast’s elbow. Arthroscopy 5:129– the elbow in asymptomatic major league baseball pitchers. 136 Radiology 227:149–154 Jacobson JA, Propeck T, Jamadar DA et al. (2003) US of the Nirschl RP (1992) Elbow tendinosis/tennis elbow. Clin Sports anterior bundle of the ulnar collateral ligament: fi nd- Med 11:851–870 ings in fi ve cadaver with MR arthrographic and O’Driscoll SW (1992) Elbow arthroscopy for loose bodies. anatomic comparison– – initial observations. Radiology Orthopedics 15(7):855–859 227:561–566 Pasternack I, Tuovinen EM, Lohman M et al. (2001) MR fi nd- Jobe FW, Cicotti MG (1994) Lateral and medial epicondylitis ings in humeral epicondylitis. Acta Radiol 42:434–440 of the elbow. J Am Acad Orthop Surg 2:1–8 Popovic N, Lemaire R (2002) Hyperextension trauma to the Khan KM, Cook JL, Bonar F et al. (1999) Histopathology of elbow; radiological and ultrasonographic evaluation in common tendinopathies. Update and implications for clin- handball goalkeepers. Br J Sports Med 36:452–456 ical management. Sports Med 27:393–408 Popovic N, Ferrara MA, Daenen B et al. (2001) Imaging overuse Kijowski R, Tuite M, Sanford M (2004) Magnetic resonance injury of the elbow in professional team handball players: a imaging of the elbow. Part I: normal anatomy, imaging bilateral comparison using plain fi lms, stress radiography, technique, and osseous abnormalities. Skeletal Radiol ultrasound and magnetic resonance imaging. Int J Sports 33:685–697 Med 22:60–67 Kijowski R, Tuite M, Sanford M (2005) Magnetic resonance Puddu G, Ippolito E, Postacchini F (1976) A classifi cation of imaging of the elbow. Part II: abnormalities of the liga- Achilles tendon disease. Am J Sports Med 4:145–150 ments, tendons, and nerves. Skeletal Radiol 34:1–18 Quinn SF, Haberman JJ, Fitzgerald SW et al. (1994) Evalua- Kijowski R, De Smet AA (2005) Magnetic resonance imag- tion of loose bodies in the elbow with MR imaging. J Magn ing fi ndings in patients with medial epicondylitis. Skeletal Reson Imaging 4:169–172 Radiol. 34:196–202 Rijke AM, Goitz HT, McCue FC (1994) Stress radiography of Klingele KE, Kocher MS (2002) Little league elbow. Valgus the medial elbow ligaments. Radiology 191:213–216 overload injury in the pediatric athlete. Sports Med Roetert EP, Brody H, Dillman CJ et al. (1995) The biomechanics 32:1005–1015 of tennis elbow. Clin Sports Med 14:47–57 Kramer J, Stiglbauer R, Engel A (1992) MR contrast in osteo- Rosenberg ZS, Beltran J, Cheung YY (1994) Pseudodefect of chondritis dissecans. J Comput Assist Tomogr 16:254–260 the capitellum: potential MR imaging pitfall. Radiology Lee GA, Katz SD, Lazarus MD (1998) Elbow valgus stress 191:821–823 radiography in an uninjured population. Am J Sports Med Sonin AH, Fitzgerald SW (1996) MR imaging of sports injuries 26:425–427 in the adult elbow: a tailored approach. Am J Roentgenol Levin D, Nazarian LN, Miller TT et al. (2005) Lateral epicondy- 167:325–331 litis of the elbow: US fi ndings. Radiology 237:230–234 Thériault G, Lachance P (1998) Golf injuries. An overview. Loftice J, Fleisig GS, Zheng N et al. (2004) Biomechanics of the Sports Med 26:43–57 elbow in sports. Clin Sports Med 23:519–530 Thornton R, Riley GM, Steinbach LS (2003) Magnetic reso- Marcelis S, Daenen B, Ferrara MA (1996) Peripheral musculo- nance imaging of sports injuries of the elbow. Top Magn skeletal ultrasound atlas. Thieme, Stuttgart, pp 79–89 Reson Imaging 14:69–86 Martin CE, Schweitzer ME (1998) MR imaging of epicondylitis. Timmerman LA, Schwartz ML, Andrews JR (1994) Preopera- Skeletal Radiol 27: 133–138 tive evaluation of the ulnar collateral ligament by magnetic 200 M. C. de Jonge and M. Maas

resonance imaging and computed tomography arthrogra- cadavers and healthy adult male volunteers. Am J Roent- phy. Am J Sports Med 22:26–32 genol 180:389–394 Van der Wall H, Storey G, Frater C et al. (2001) Importance of Werner SL, Fleisig GS, Dillman CJ et al. (1993) Biomechanics positioning and technical factors in anatomic localization of the elbow during baseball pitching. J Orthop Sports Phys of sporting injuries in scintigraphic imaging. Semin Nucl Ther 17:274–278 Med 31:17–27 Werner SL, Murray TA, Hawkins RJ et al. (2002) Relationship Verhagen RA, Maas M, Dijkgraaf MG et al. (2005) Prospective between throwing mechanics and elbow valgus in profes- study on diagnostic strategies in osteochondral lesions of sional baseball pitchers. J Shoulder Elbow Surg 11:151– the talus. Is MRI superior to helical CT? J Bone Joint Surg 155 Br 87-B:41–46 Wilder RP, Sethi S (2004) Overuse injuries: tendinopathies, Ward SI, Teefey SA, Paletta GA Jr et al. (2003) Sonography stress fractures, compartment syndrome, and . of the medial collateral ligament of the elbow: a study of Clin Sports Med 23:55–81, vi