Scapular, Clavicular, Acromioclavicular and Sternoclavicular Injuries 169

Scapular, Clavicular, Acromioclavicular and 11 Injuries

Peter Brys and Eric Geusens

CONTENTS 11.1 Introduction 11.1 Introduction 169 11.1.1 Scapula 169 11.1.1 11.1.2 169 Scapula 11.1.3 Acromioclavicular Joint 169 11.1.4 Sternoclavicular Joint 170 The scapula is a fl at bone with three prominences, 11.2 Imaging 171 11.2.1 Plain Radiography 171 the spine and acromion, the glenoid, and the coracoid 11.2.1.1 Scapula 171 process. Medial to the base of the coracoid process is 11.2.1.2 Clavicle 171 the scapular notch arched by the superior transverse 11.2.1.3 AC-Joint 171 scapular . The spinoglenoid notch arched by 11.2.1.4 SC Joint 171 11.2.2 Ultrasound 172 the inferior transverse scapular ligament is situated 11.2.2.1 AC Joint 172 between the lateral margin of the base of the scapular 11.2.2.2 SC Joint 172 spine and the dorsal side of the glenoid. Both notches 11.2.3 CT 172 are important fi xation points along the course of the 11.2.3.1 Scapula and Clavicle 172 suprascapular nerve. 11.2.3.2 SC Joint 172 11.2.4 MRI 172 11.2.4.1 AC Joint 172 11.2.4.2 SC Joint 172 11.1.2 11.2.5 Scintigraphy 173 Clavicle 11.3 Specifi c Overuse Trauma 173 11.3.1 Scapula 173 The growth plates of the medial and lateral clavicular 11.3.1.1 Fractures 173 11.3.1.2 Lateral Acromial Apophysitis 173 epiphyses do not fuse until the age of 25 years. The 11.3.1.3 Stress-related Growth Plate Injury of the deltoid, trapezius, and pectoralis major muscles have Coracoid Process 174 important attachments to the clavicle. The deltoid 11.3.1.4 Stress Fractures 174 muscle inserts onto the anterior surface of the lateral 11.3.1.5 Suprascapular Nerve Entrapment (SSNE) 174 third of the clavicle, and the trapezius muscle onto the 11.3.1.6 Long Thoracic Neuropathy 175 posterior aspect. The pectoralis major muscle inserts 11.3.2 Clavicle 175 onto the anterior surface of the medial two thirds. 11.3.2.1 Fractures 175 11.3.2.2 Lateral Clavicular Osteolysis (LCO) 175 11.3.2.3 Stress Fractures 176 11.3.3 AC Joint 177 11.1.3 11.3.3.1 Sprain/Dislocation 177 Acromioclavicular Joint 11.3.3.2 Osteoarthritis (OA) 178 11.3.4 SC Joint 179 The synovium-lined AC joint has interposed between 11.3.4.1 Sprain/Dislocation 179 its fi brocartilaginous joint surfaces a fi brocartilagi- Things to Remember 180 nous disc of variable size which is frequently com- References 180 pletely absent (Wickiewicz 1983). The joint has a thin capsule, reinforced by the AC of which P. Brys, MD E. Geusens, MD the superior one is continuous with the deltoid and Dept. of Radiology, University Hospitals Leuven, Herestraat 49, trapezius aponeuroses. The lateral clavicle is anchored 3000 Leuven, Belgium to the coracoid process by the coracoclavicular liga- 170 P. Brys and E. Geusens

Box 11.1. Plain radiography Box 11.4. MRI

● Initial modality in osseous or articular disease ● No clear role in sprain or isolated disease of ● Tailored approach and good quality essential AC joint ● ● Only AC stress views when therapeutical con- Limited role in SC sprain sequences ● Soft tissue trauma ● No special SC views when CT available ● Posterior pain: muscle denervation? ● Low sensitivity for early stress fracture or LCO paralabral cyst?

Box 11.2. CT Box 11.5. Scintigraphy ● Second stage evaluation of fractures or SC dis- location ● When plain radiography is negative ● If plain radiography negative and bone scan ● Suspected active osseous disease positive ● Occult fracture ● Stress fracture Box 11.3. Ultrasound ● Growth plate injury or apophysitis ● Limited role in AC joint ● Arthritis or osteoarthritis ● Lateral clavicular osteolysis ● AC sprain: type 1 or muscular status ● AC joint: joint distension? Arthrosynovial cyst? ● Limited role in SC joint: distension? ● Posterior shoulder pain/weakness: paralabral cyst?

● Soft tissue trauma Trapezoid Conoid ligament AC ligament ligament ment, composed of the lateral trapezoid and medial conoid parts (Fig. 11.1). The static joint stabilizers are the AC ligaments, controlling the horizontal stability, clavicle and the CC ligament controlling the vertical stability. acromion The dynamic stabilizers are the deltoid and trapezius muscles. The trapezius muscle attaches at the dorsal coracoid aspect of the acromion, part of the anterior deltoid muscle inserts on the clavicle medial to the AC joint. Their force vectors prevent excessive superior migra- tion of the distal clavicle after disruption of the AC and CC ligaments alone (Wulker 1998). Fig. 11.1. Normal anatomy: the acromioclavicular and cora- coclavicular ligament, the latter with its medial conoid and lateral trapezoid parts 11.1.4 Sternoclavicular Joint the cartilage of the fi rst rib (Fig. 11.2). Interposed between the fi brocartilaginous joint surfaces is a The synovium-lined SC joint is formed by the medial usually complete fi brocartilaginous disc, which acts clavicle, the clavicular notch of the manubrium, and to reduce the incongruities between the articulating Scapular, Clavicular, Acromioclavicular and Sternoclavicular Joint Injuries 171 joint surfaces, and as a shock absorber against medial case of a fractured coracoid process, the patient’s translation of the clavicle. The anterior and posterior pain usually precludes abduction. The fracture may SC ligaments are thickenings of the joint capsule. The be demonstrated with the so-called modifi ed axillary interclavicular ligament connects the with view (Wa l l ac e and Hellier 1983). the capsular ligaments and the upper . The costoclavicular or rhomboid ligament runs from the 11.2.1.2 fi rst rib to the rhomboid fossa at the inferior side of Clavicle the medial clavicular metaphysis. This fossa should not be mistaken for a tumor when seen on radio- The Zanca view, an anteroposterior projection with graphs. The SC joint is freely movable and functions 15q of cephalic angulation, projects the lateral and almost like a ball-and-socket joint with motion in most of the middle third of the clavicle free of almost all planes, including rotation (Lucas 1973). overlying adjacent bones (Zanca 1971). Although The ligamentous support is so strong that it is one not required on a routine basis, visualisation of the of the least commonly dislocated in the body medial third of the clavicle is accomplished with (Wirth and Rockwood 1996). 40° cephalic angulation (Rockwood and Wirth 1996). Anterior SC ligament 11.2.1.3 Interclavicular AC-Joint clavicle ligament

The best view of the AC-joint is the Zanca view. In case of an AC-trauma it is recommended to obtain Articular disc an upright view without the patient allowed to sup- port his with the opposite , which might 1 st rib Costoclavicular ligament reduce any dislocation (Neer and Rockwood 1975). manubrium Stress or weighted views may be required after an AC-joint injury to allow more accurate differentia- tion between type 2 and 3 AC-sprains. An axillary Fig. 11.2. Normal anatomy: the sternoclavicular joint view can be helpful to determine the position of the clavicle with respect to the acromion.

11.2.1.4 SC Joint

Standard radiographic views of the SC joint include 11.2 posteroanterior and oblique views. However, they Imaging are often inadequate due to overlap of the medial clavicle with the sternum, the first rib, and the 11.2.1 spine. Special projections have been described to Plain Radiography aid in the evaluation. Unless done by an experi- enced technologist these special views can be tech- Diagnostic plain fi lms are tailored to the clinical fi nd- nically difficult to perform and interpret, limiting ings and should be of impeccable quality. their utility and reproducibility (Brossman et al. 1996). 11.2.1.1 • The Rockwood projection, also called the ‘ser- Scapula endipity view, is an anteroposterior projection obtained with a 40° cephalic tilt, centered on the Routine views of the scapula include the AP view manubrium. The cassette is placed under the abducting the 90q and the lateral view or scapu- upper part of the and neck so that the lar Y. The axillary view, which requires abduction clavicle is projected in the middle of the fi lm. In of the arm, gives an excellent view on the anterior an anterior dislocation, the affected clavicle is pro- acromion, the glenoid, and the coracoid process. In jected superior to the normal clavicle, and with 172 P. Brys and E. Geusens

posterior dislocation it is projected inferior to it 11.2.3 (Fig. 11.3) (Rockwood and Wirth 1996). Other CT special views, such as the Hobbs view and Heinig view (Hobbs 1968; Heinig 1968) are rarely per- 11.2.3.1 formed today and are currently replaced by mul- Scapula and Clavicle tidetector CT. • Stress maneuver: a reducible or intermittent SC With its excellent bony detail and its multiplanar and dislocation can look misleadingly normal on a 3D reconstruction capabilities, modern multi-detec- routine radiograph. A stress maneuver helps to tor CT equipment is the imaging technique of choice avoid this problem. This maneuver is performed in the evaluation of fractures and stress fractures. by bringing the ipsilateral arm across the chest and pulling against the contralateral elbow (Cope 11.2.3.2 1993). SC Joint

CT is particularly valuable if an SC joint disloca- tion is suspected. Advantages are the short procedure time, wide availability, and the quality of 3D-refor- mating with MDCT in the assessment of the direc- tion and degree of a (sub)luxation and evaluation of fractures. It is recommended to image both sides, as comparison is often helpful in assessing the degree of abnormality. CT can be acquired in a neutral position alone or with the stress maneuver as described in the plain fi lm section, which increases the sensitivity (Burnstein and Pozniak 1990; Cope 1993). If there is strong suspicion of secondary vascular compro- Fig. 11.3. Anterior subluxation of the right sternoclavicular joint. Rockwood view showing a slightly more cranial projec- mise or impingement by a posterior dislocation, the tion of the right clavicle compared to the left (black arrows), study can be performed with IV contrast to allow consistent with an anterior subluxation. An AP view (not optimal visualization of the adjacent vessels. shown) revealed no abnormalities

11.2.4 MRI 11.2.2 Ultrasound 11.2.4.1 AC Joint 11.2.2.1 AC Joint The role of MRI in isolated AC pathology is not well established. In addition to the fi ndings visible on In a trauma setting, US can be used to confi rm a grade standard radiographs, soft tissue abnormalities (cap- 1 sprain, or in the assessment of the status of the sur- sular hypertrophy, joint effusion, CC ligaments, mus- rounding musculature. In chronic disease, US allows cular attachments) and subchondral bone marrow the evaluation of capsular distension and presence of edema may be demonstrated. The coronal oblique soft tissue lesions like arthrosynovial cysts. plane best demonstrates the AC joint. The parasagit- tal plane roughly corresponds to the radiographic 11.2.2.2 supraspinatus outlet view. SC Joint 11.2.4.2 The role of US of the SC joint is limited. It can be SC Joint used for the assessment of capsular bulging or the position of the joint surfaces in suspected dislocation, MRI is far superior to CT in its ability to defi ne bone the latter if CT is not readily available. marrow abnormalities, disc- and cartilage injury, Scapular, Clavicular, Acromioclavicular and Sternoclavicular Joint Injuries 173

joint effusion, and to evaluate the extra-articular soft- In the workup of patients with posttraumatic pain tissues (Fig. 11.4).To allow appropriate evaluation of due to sports injuries, which is suspected to be of all involved structures, imaging in three orthogonal osseous origin, it is a useful next diagnostic step when planes is recommended (Klein et al. 1997; Bross- plain fi lms are negative. Examples of injury in which man et al. 1996). There may be diffi culty in obtaining bone scintigraphy may be helpful are occult frac- good quality MR images of the SC joint: the small tures, stress fractures or other stress-related injury, joint is poorly imaged with the body coil. In surface lateral clavicular osteolysis, and symptomatic AC or coil imaging both the applied coil and the SC joint SC osteoarthritis. move with patient breathing, causing severe artifact. Vascular pulsations and swallow also cause artifacts. This diffi culty in imaging, combined with most radi- ologist’s limited experience with SC joint imaging, and the availability of CT has prevented the emer- 11.3 gence of MRI of the SC joint (Klein et al. 1997). Specifi c Overuse Trauma

11.3.1 Scapula

11.3.1.1 Fractures

Scapular fractures are usually the result of a direct blow to the scapular area. Fractures of the scapular body are rare in athletes. Glenoid fractures are asso- a ciated with glenohumeral dislocations although an avulsion fracture of the infraglenoid tubercle may occur due to forceful contraction of the triceps. Frac- tures of the acromion most frequently are caused by a direct blow. An avulsion of the anterior acromion may result from deltoid muscle forces. Coracoid pro- cess fractures result from direct trauma or avulsion. Avulsion is possible with contraction of the short head of the biceps or the coracobrachialis muscle, or as a result of traction from the coracoclavicular b ligament in association with a sprain of the AC joint. Fig. 11.4a,b. A 19-year-old male. Trauma to the left SC joint The latter may be seen as an apophyseal avulsion resulting in a Salter II fracture of the left clavicular head. in adolescents before closure of the growth plate a Axial MR image (4000/34) shows right normal and left torn: between 15 and 18 years of age, since the ligament anterior SC ligaments (long arrows), articular discs (short is often stronger than the growth plate (Salter and arrows), and posterior SC ligaments (arrowheads). b Axial Harris 1963). MR STIR image shows left joint effusion (long arrow), right normal and left torn discs (short arrows), and bone marrow 11.3.1.2 edema within the epiphysis of the left clavicular head (arrow- head). LBV, left brachiocephalic vein; C, clavicle; T, trachea; Lateral Acromial Apophysitis M, manubrium. [Reprinted from Benitez et al. (2004) with permission] Repetitive contraction of muscles attaching on an apophysis can produce microfractures or apophy- seal irritation, also called traction apophysitis. When 11.2.5 apophyses begin to ossify, they are susceptible to Scintigraphy overstress injuries. In throwing movements the del- toid muscle undergoes repeated vigorous contrac- Bone scintigraphy is a very sensitive technique for tion. The acromial apophysis is the weakest part in detection of early changes related to osseous injuries. the wide origin of the deltoid muscle and the central 174 P. Brys and E. Geusens

portion, the strongest belly attaches at this region •American football: two similar cases at the junc- (Morisawa et al. 1996). An apophysitis at the tip tion of the acromion with the scapular spine. of the coracoid process from the pull of the short Both occurred in offensive linemen whose train- head of the biceps and the coracobrachialis is also ing included intensive weight-lifting (Schils et al. described (Gregg and Torg 1988). Plain radiography 1990; Wa r d et al. 1994). typically shows fragmentation, irregularity, and scle- •Cricket: in a fast bowler at the lateral border of rosis of the ossifi cation centre (Fig. 11.5). The process the scapula, most likely at the origin of the teres resolves without complication. minor muscle (De Villiers et al. 2005). •Golf: at the left side in a right-handed female player at the base of the acromion, extending into the spine, probably induced by contraction of the posterior fi bres of the deltoid as the head of the golf club swings forward to strike the ball (Hall and Calvert 1995). •Jogging with hand-held weights: at the medial site of the supraspinatus fossa due to overuse of the supraspinatus muscle stabilizing the humeral head (Veluvolu et al. 1988). Fig. 11.5. Lateral acromial apophysitis at the left side. AP view • showing a mixed lytic-sclerotic, and slightly fl attened aspect Tennis: in a female elite player between the ven- of the acromial apophysis. [Reprinted from Anderson et al. tral and middle third of the acromion 2 years after (1998) with permission] adequate subacromial decompression. The lesion most likely occurred due to repetitive vigorous bending stress (Rupp et al. 1998). 11.3.1.3 •Trapshooting: two reports of probably the same Stress-related Growth Plate Injury of the Coracoid female athlete describe a stress fracture of the Process coracoid process, resulting from repeated direct trauma by the recoil of the butt of the rifl e (Boyer Injuries of the coracoid process physis are rare and 1975; Sandrock 1975). commonly associated with AC joint sprain. A chronic, stress-related injury to this physis is described in Plain radiography continues to be the primary archery caused by the considerable amount of energy method for diagnosis, but its limitations in the early load and shots required in training and tournaments. detection of these injuries are well known. MRI has Plain radiography demonstrated persistence of the a comparative sensitivity to bone scan with the addi- growth plate at the base of the coracoid process tional advantage of depicting the lesion, especially (Naraen et al. 1999). the surrounding bone marrow and soft tissue edema. MDCT is excellent in depicting the presence and 11.3.1.4 extension of the fracture line and callus formation. Stress Fractures 11.3.1.5 Sports-related stress fractures of the scapula and Suprascapular Nerve Entrapment (SSNE) clavicle are rare. Consequently the index of suspi- cion for these lesions is low, which may delay diag- The suprascapular nerve is a mixed motor and sen- nosis and appropriate treatment. Low suspicion of a sory nerve providing motor supply to the supraspi- stress fracture in these bones may lead to an erro- natus and infraspinatus muscle. Causes of supra- neous diagnosis of a tumoral or infectious lesion. scapular nerve injury are anatomical variants of the A detailed occupational history may overcome the suprascapular or spinoglenoid notch, compressive problem. These stress fractures can occur either as a mass lesions, which most frequently are paralabral result of repetitive loading at the point of muscular cysts at the level of the spinoglenoid notch (Ticker attachments to bone or as a result of impact loading et al. 1998), direct trauma such as a fracture of the (Brukner 1998). scapula, direct blow to the shoulder, or traction on There are isolated reports of scapular stress frac- the nerve through a pull on the upper extremity, and tures in a variety of sports: dynamic entrapment. Scapular, Clavicular, Acromioclavicular and Sternoclavicular Joint Injuries 175

Dynamic nerve entrapment occurs at the supra- 11.3.2 scapular or spinoglenoid notch during violent or Clavicle repeated scapular motion. In athletes this appears more frequently at the spinoglenoid notch, whereas 11.3.2.1 in the general population it occurs mainly at the Fractures suprascapular notch (Montagna and Colonna 1993;Ferretti et al. 1998). In the majority of cases Fractures of the clavicle are common. As many as 90% sports-related dynamic entrapment occurs in over- occur as the result of a fall directly on the shoulder, head sports such as baseball, tennis, and weightlift- a small number after direct blow, and rarely a fall on ing. Most frequently affected by entrapment at the an outstretched hand. The middle third is involved spinoglenoid notch are professional volleyball play- in 65%–80%, the lateral in 15%–30%, and the medial ers. Several mechanisms have been proposed but in 5%. excessive traction or stretching of the nerve is the most plausible mechanism of trauma. 11.3.2.2 The diagnosis is based primarily on clinical fi ndings, Lateral Clavicular Osteolysis (LCO) confi rmed by EMG. Imaging studies may demonstrate an etiological diagnosis. US and MRI may identify a LCO is an uncommon, self-limiting condition with paralabral cyst. In addition MRI is able to identify signs uncertain pathogenesis characterized by progressive of muscular denervation, including edema in an early resorption of the lateral end of the clavicle (Cahill stage, and fatty infi ltration and atrophy in later stages 1982; Matthews et al. 1993). Two types are described (Ludig et al. 2001). Entrapment at the suprascapular with the same radiological imaging and pathologic notch will result in denervation of both supra- and features: infraspinatus muscles, entrapment at the spinoglenoid • Posttraumatic: after a single or repeated episodes notch in isolated infraspinatus denervation. of local trauma which can be a fracture or AC dis- location. However, usually the trauma is relatively 11.3.1.6 minor. The osteolytic process begins as early as Long Thoracic Neuropathy 2–3 weeks and as late as several years after the injury. The long thoracic nerve, the sole innervation to the • Stress-induced: overuse injury caused by repeti- serratus anterior muscle, courses downward and lat- tive microtrauma, most commonly seen in adult erally along the outer surface of the muscle which weightlifters (Scavenius and Iversen 1992) and arises from the fi rst eight to nine ribs and inserts athletes who are engaged in strenuous physical on the costal surface of the scapula along its medial exercise involving use of the upper extremities. It border. It serves to protract the scapula and maintain is caused by repetitive compression of the distal the medial border of the scapula against the thorax. clavicle at the AC joint encountered during lift- Isolated paralysis of the serratus anterior is a well- ing activities, particularly the bench press (Haupt recognized clinical entity accounting for the charac- 2001). A higher incidence of bilateral involvement teristic scapular winging seen with weakness of this is noted in this type. muscle, most pronounced at the inferior margin of the scapula. Many traumatic and nontraumatic causes Plain radiographs are not sensitive to the early have been reported. This injury has been reported stage of the disease. Initial fi ndings often are subtle, to occur in almost every sport. However, the most including osteopenia of the distal clavicle, and loss of common sport reported to cause the injury is tennis, the clavicular subarticular cortex (Levine et al. 1976; especially the act of serving. The common theme Kaplan and Resnick 1986). However, early recogni- in sports-related cases is that the injury occurred tion and treatment with immobilisation can shorten when the ipsilateral arm was in an outstretched an the course of the process. The condition progresses into unusually overhead position, suggesting the nerve a lytic phase in which cystic areas, irregularity of the was subjected to traction (Gregg et al. 1979). This articular cortex, periarticular erosions, osteolysis, and paralysis is usually apparent on clinical examination soft tissue swelling can be seen. It may be associated and confi rmed by EMG. CT and MRI usually are not with osteopenia and erosion of the acromion (Levine necessary unless other disease such as cervical disc et al. 1976). If untreated this lytic phase may last 12– herniation is suspected. 18 months and osteolysis may progress to include the 176 P. Brys and E. Geusens

distal 0.5–3 cm of the clavicle, resulting in an increased the clavicle may be considered a lever with is axis of AC joint space (Kaplan and Resnick 1986). rotation close to the sternoclavicular joint. It is pulled Once the lytic phase has stabilized, reparative down by the pectoralis major muscle, subclavius changes occur over a period of 4–6 months, result- muscle, and deltoid musculature, counterbalanced by ing in either complete reconstitution or partial refor- the cranial pull of the sternocleidomastoideus and mation with a permanently widened AC joint space trapezius muscles. The point of maximum stress is (Fig. 11.6) (Kaplan and Resnick 1986). immediately lateral to the strongly anchoring costo- The role of MRI and its features of LCO are not well clavicular and sternoclavicular attachments (Calvo documented. Although not very specifi c, the most et al. 1995). constant fi nding is edema in the distal clavicle (Yu As in the scapula, there are isolated reports of cla- et al. 2000; Patten 1995; De la Puenta et al. 1999). vicular stress fractures in several sports: Other frequent fi ndings are clavicular subchondral • Baseball: at the medial side in a professional third cortical thinning, subchondral cysts, peri-articular baseman with high demands on his throwing soft tissue swelling and joint space widening. shoulder (Wu and Chen 1998). • Gymnastics: in a 10-year-old gymnast through a 11.3.2.3 deep rhomboid fossa, possibly caused by the pull Stress Fractures of sternocleidomastoideus and pectoralis major inserting on the medial aspect of the clavicle Sports-related stress fractures of the clavicle are rare, (Fallon and Fricker 2001). almost invariably occurring in the medial part of • Human tower construction: in this traditional the diaphysis. From a biomechanical point of view, Catalan sport the medial clavicle is pushed down

a b

c d

Fig. 11.6a–d. Lateral clavicular osteolysis in a judo athlete. a Unsharply marginated subchondral erosion at the inferior margin of the lateral end of the clavicle. Normal width of the AC joint space. b At 8 weeks later: widening of the AC joint space with ill- defi ned resorption of the lateral clavicle, and loss of the subchondral bone plate in the proximal part at the acromial side. c At 8 months later: further resorption of the lateral clavicle and increased width of the joint space. The margins are less ill-defi ned. d Control after 15 months: partial reconstitution of the joint space width and now sharply marginated lateral end of the clavicle Scapular, Clavicular, Acromioclavicular and Sternoclavicular Joint Injuries 177

by the weight of other athletes while the surround- injury while being tackled or during collision with ing muscles are pulled upon (Roset-Llobet and another player or the ground (Kelly et al. 2004) In Salo-Orfi la 1998). ice hockey AC sprains, caused by collisions with an • Javelin throwing: in an elite athlete, caused by opponent or the boards, are the third most common repeated stress from the contraction of the cla- lesions (Flik et al. 2005). In wrestling the most com- vicular portion of the deltoid and pectoralis major monly injured area is the shoulder in which 19% are muscles (Adolfsson and Lysholm 1990). AC joint separations resulting from a direct blow to • Rowing: in a lightweight sculler, occurring at 1 cm the shoulder against the mat during the so-called lateral to the SC joint, most likely resulting from take down (Pasque and Hewett 2000). Other sports cyclic scapular protraction and retraction (Abbot with frequent AC sprains are alpine skiing and snow- and Hannafi n 2001). boarding due to falls or collisions with other skiers • Springboard diving: in a male diver, resulting or trees (Kocher and Feagin 1996), and bicycling from transmission of stress from his to the in which a common injury pattern involves a lateral midportion of the clavicle on entry in the water or AC separation from landing on (Waninger 1997). the shoulder when thrown from the bicycle. • Weightlifting: the only described stress fracture of Initially injuries to the AC joint were graded I to III the lateral clavicle occurred in a female athlete at as proposed by TOSSY according only to the degree of 1 cm from the AC joint due to structural fatigue injury to the AC and CC ligaments (Tossy et al. 1963). (Shellhaas et al. 2004). Rockwood (1984) added three additional types, all subsets of Tossy type III (Fig. 11.7, Table 11.1). The grading of AC injuries is typically based on 11.3.3 plain fi lm analysis: AC Joint

Table 11.1. Rockwood classifi cation of AC injuries 11.3.3.1 Sprain/Dislocation Type 1 Sprain AC ligaments and intact CC ligament Type 2 Subluxation with rupture AC ligaments and sprain AC sprains are common during athletic activities, CC ligament most frequently occurring directly by a blow to the Type 3 Dislocation with rupture AC ligaments and CC acromion (a fall or other contact) with an adducted ligament humerus driving the acromion medially and inferi- Type 4 Dislocation with posterior dislocation of the clavicle orly, or indirectly by a fall on the outstretched hand or elbow with a superiorly directed force. Type 5 Dislocation with severe upward displacement of clavicle into the subcutis AC-sprains are frequent in contact sports: in American football quarterbacks 40% of all shoul- Type 6 Dislocation of the clavicle inferiorly, locked under the coracoid process der injuries are AC sprains, resulting from a contact

Type 1 Type 2 Type 3

Type 4 Type 6 Type 5

Fig. 11.7. Rockwood classifi cation of acromioclavicular joint injuries 178 P. Brys and E. Geusens

• In type 1 plain fi lms are normal. 11.3.3.2 • A type 2 is characterised by widening of the joint Osteoarthritis (OA) space and slight upward displacement of the lat- eral clavicle, less than the width of the acromion. OA occurs early and frequently because the adult AC The width of the joint space is pathologic if more joint (ACJ) cannot compensate for the incongruity of than 7 mm in men, more than 6 mm in women, or the joint surfaces (Petersson 1987). OA is the most with a difference of more than 2 mm compared common cause of AC-related pain (Shaffer 1999). to the uninjured side (Petersson and Redlund- Causes of OA related to sports activity are AC sprains Johnell 1983). The assessment of upward dis- and chronic repetitive loading. With ruptured AC placement of the clavicle relative to the acromion ligaments, the CC ligament is unable to control ade- should be based on the alignment of the inferior quately anteroposterior translation, or rotation of the margins. distal clavicle (Debski et al. 2001). Chronic repetitive • In type 3 there is an upward dislocation of the loading is typically seen in overhead athletes, weight clavicle, more than the width of the acromion. lifters, and golf players. In overhead athletes rotation Rupture of the CC ligament is very likely if there of the distal clavicle, shear forces and high compres- is a difference of 5 mm or more between the two sive forces from the deltoid, are believed to contribute sides (Neer and Rockwood 1975). The normal to AC degeneration (Renfree and Wright 2003). coracoclavicular distance is 11–13 mm. Examples of sports with increased prevalence of OA • To disclose the posterior dislocation of the clavi- are swimming, baseball, and handball ( Turnbull cle in type 4, an axillary or modifi ed axillary view 1998; JOST et al. 2005). In weightlifting the ACJ may be required. becomes a weight-bearing joint with high compres- • A severely upward displaced clavicle, more than sive forces. In golf injuries to the shoulder are mainly 100% of the CC distance, is the hallmark of a restricted to the lead shoulder (left shoulder in right- type 5 injury. handed players) and most frequently related to the ACJ (Mallon and Colosimo 1995). Maximal forces Since treatment for type 3 injuries is less clear and about the ACJ in golf are attained at the top of the controversial (Phillips et al. 1998), weighted views back swing and at the end of the follow-through, are only required when their diagnosis may alter the which is repeated several hundred times per day treatment strategy of the local surgeon. (Bell et al. 1993; Mallon and Colosimo 1995). While in adults dislocation of the AC joint accounts On routine radiography the ACJ is not loaded in for 12% of all dislocations of the shoulder (Rowe compression. Consequently, the joint space does not 1968), a true AC dislocation is very rare before the age depict the thickness of the cartilage. A loaded view, of 16. Usually the trauma results in a physeal separa- obtained by forced adduction of the humerus by tion of the lateral clavicle. While the clavicular epiph- pulling the elbow with the opposite hand, may dem- ysis remains intact in the periosteal tube, the lateral onstrate an additional 27% of OA (Stenlund et al. clavicle shows upward displacement through a tear in 1992). However, the role of this view is not well-estab- the thick periosteal tube, also called a pseudodisloca- lished. Since OA may also be present on plain fi lms in tion (Kocher et al. 2000). patients without symptoms (Zanca 1971; Bonsell et The role of ultrasound in AC sprains is not well al. 2000), the prevalence of OA on MRIs of asymptom- established. US is sensitive in the detection of type 1 atic subjects has been reported to be as high as 48% sprains: fi ndings are distension of the joint space, and 82% (Needell et al. 1996; Shubin Stein 2001 et tenderness to sonographic palpation, and stripping al.), and no real correlation was found between MRI of the periosteum from the medial clavicular head. and clinical fi ndings in the ACJ (Jordan et al. 2002), Since treatment for type 3 injuries is less clear and imaging fi ndings should always be correlated with controversial (Phillips et al. 1998), US may be valu- symptoms. able in differentiation between type 3 lesions based on the presence or absence of detachment of muscle insertions, the dynamic joint stabilizers (Heers and Hedtmann 2005). In the same way, MRI might be a valuable tool to decide between conservative and operative treatment based on the associated soft tissue damage. Scapular, Clavicular, Acromioclavicular and Sternoclavicular Joint Injuries 179

11.3.4 portion of the clavicle. Typical situations are an ath- SC Joint lete getting the knee of an opponent or a kick directly to the front of the medial clavicle. 11.3.4.1 Approximately 25% of posterior dislocations Sprain/Dislocation are associated with some form of complication as the medial clavicle can impinge on vital mediasti- No more than 2%–3% of all dislocations involving nal structures (Neer and Rockwood 1975). They the pectoral girdle occur at the SC joint. SC disloca- consist of pneumothorax, laceration of the superior tions are classifi ed as either anterior or posterior, vena cava, compression of the venous structures of the anterior one being far more common. In nearly the neck, compression or rupture of the trachea, rup- 150 traumatic SC dislocations a sports-related injury ture of the esophagus, occlusion or compression of accounted for 21% (Wirth and Rockwood 1996). the subclavian or carotid artery, and changes in voice Two types of injury may result in a SC dislocation: caused by compression of the recurrent laryngeal The most common is an indirect blow to the shoulder, nerve. A high index of suspicion is required to deter- which may be seen in contact athletes. mine the presence of these serious complications, Subsequently the clavicle acts as a lever through which may manifest insidiously. the fulcrum of the costoclavicular ligament (Rogers In patients younger than 25 years all SCJ disloca- 1983). An anterolateral blow results in anterior, a pos- tions consist primarily of physeal separations, mim- terolateral blow in posterior dislocation (Fig. 11.8). icking SC dislocations (Wirth and Rockwood 1996). Contact sports (especially martial arts, American The epiphysis stays attached to the sternum via the football, and rugby) and motorcycle injuries are the sternoclavicular ligaments and the medial clavicular commonest causes of posterior dislocation. Typically shaft displaces anteriorly or posteriorly. Although a blow to the posterolateral aspect of the shoulder rare, true posterior dislocations in children exist and with the arm adducted and fl exed occurs during a warrant surgical reduction. piling-on injury in American football when a player Injuries to the SC joint are graded I to III accord- holds the ball and tries to avoid his opponents (Wirth ing to Allmann (1967) (Table 11.2). and Rockwood 1996). In American football quarter- backs, the frequency of SC sprain was reported as Table 11.2. Allmann classifi cation of SC injuries 3.4% (Kelly et al. 2004). A posterior dislocation may also result from a direct blow to the anterior medial Type 1 Mild sprain with intact ligaments and a stable joint Type 2 Moderate sprain with subluxation and possible par- tial rupture of the ligaments Dislocation Type 3 Dislocation with complete disruption of the sup- porting ligaments Impact

Dislocations of the SC joint are notoriously diffi - Dislocation cult to characterize on plain radiography. The diag- nosis is usually evident on CT scan, and one should directly proceed to CT instead of focusing on special plain fi lm projections (Fig. 11.9). US can be used to make the diagnosis if CT is not readily available. On MRI of 41 patients imaged with complaints related Impact to a SC trauma, the most common sites of SC joint soft tissue injury were the articular disc (80%), the Fig. 11.8. Mechanism of sternoclavicular dislocations caused by an indirect blow to the shoulder. Right: anterolateral blow anterior SC ligament (73%), and the posterior SC resulting in an anterior sternoclavicular dislocation. Left: ligament (39%). Injuries to the interclavicular and posterolateral blow resulting in a posterior sternoclavicular costoclavicular ligaments were rare (Benitez et al. dislocation 2004). 180 P. Brys and E. Geusens

References

Abbot AE, Hannafi n JA (2001) Stress fracture of the clavicle in a female lightweight rower. Am J Sports Med 29:370–372 Adolfsson L, Lysholm J (1990) Case report: clavicular stress m fracture in a javelin thrower. Clin Sports Med 2:41–45 Allmann FI (1967) Fractures and ligamentous injuries of the c clavicle and its articulations. J Bone Joint Surg Am 49:774– 784 Anderson J, Read JW, Steinweg J (eds) (1998) Atlas of imaging in sports medicine. McGraw-Hill Book Company, Australia, p 125 Bell R, Acus R, Noe D (1993) A study of acromioclavicular joint forces (abstract). J Shoulder Elbow Surg 2(suppl 1–2):S24 Benitez CL, Mintz DN, Potter HG (2004) Magnetic resonance imaging of the sternoclavicular joint following trauma. J Clin Imaging 28:59–63 Bonsell S, Persall AW, Heitman RJ et al. (2000) The relation- ship of age, gender, and degenerative changes observed on Fig. 11.9. Posterior subluxation of the right sternoclavicular radiographs of the shoulder in asymptomatic individuals. joint. Axial CT slice showing a step-off at the level of the right J Bone Joint Surg Br 82:1135–1139 sternoclavicular joint with asymmetrical width of the joint Boyer D Jr (1975) Trapshooter’s shoulder: stress fracture of the coracoid process. J Bone Joint Surg Am 57:862 space and slight posterior displacement of the medial end of Brossmann J, Stabler A, Preidler KW et al. (1996) Sternocla- the clavicle (c) relative to the sternal manubrium (m) vicular joint; MR imaging-anatomic correlation. Radiology 198:193–198 Brukner P (1998) Stress fractures of the . Sports Med 26:415–424 Burnstein MI, Pozniak MA (1990) Computed tomography with stress maneuver to demonstrate sternoclavicular joint dis- location. J Comput Assist Tomogr 14(1):159–160 Things to Remember Cahill B (1982) Osteolysis of the distal part of the clavicle in male athletes. J Bone Joint Surg Am 64A:1053–1058 1. In sports lesions plain fi lms tailored to the Calvo E, Fernandez-Yruegas D, Alvarez L et al. (1995) Bilateral clinical fi ndings and of impeccable quality stress fracture of the clavicle. Skeletal Radiol 24:613–616 will signifi cantly increase diagnostic perfor- Cope R (1993) Dislocations of the sternoclavicular joint. Skel- etal Radiol 22:233–238 mance. De la Puente R, Boutin R, Theodorou D et al. (1999) Post-trau- matic and stress-induced osteolysis of the distal clavicle: 2. Because of their low prevalence and low index MR fi ndings in 17 patients. Skeletal Radiol 28:202–208 of suspicion, sports-related stress fractures of de Villiers R, Pritchard M, de Beer J et al. (2005) Scapular stress the scapula and clavicle may be mistaken for a fracture in a professional cricketer and a review of the lit- erature. S Afr Med J 95(5):312–317 tumoral or infectious lesion unless a detailed Debski RE, Parsons IM, Woo SL-Y et al. (2001) Effects of capsu- occupational history is taken. lar injury on the acromioclavicular joint mechanics. J Bone Joint Surg Am 83:1344–1351 3. In sports-related AC joint or posterior shoul- Fallon KE, Fricker PA (2001) Stress fracture of the clavicle in a der pain, radiologists respectively should also young female gymnast. Br J Sports Med 35:448–449 Ferretti A, de Carli A, Fontana M (1998) Injury of the supra- consider a possible lateral clavicular osteoly- scapular nerve at the spinoglenoid notch. The natural his- sis or a suprascapular nerve entrapment syn- tory of infraspinatus atrophy in volleyball players. Am J drome. Sports Med 26:759–763 Flik K, Lyman S, Marx RG (2005) American collegiate men’s ice 4. In sternoclavicular joint dislocation one hockey. An analysis of injuries. Am J Sports Med 33(2):183– 187 should immediately proceed to CT instead of Gregg J, Torg E (1988) Upper extremity injuries in adolescent focusing on special plain fi lm projections. tennis players. Clin Sports Med 7:371–385 Gregg JR, Labosky D, Harty M et al. (1979) Serratus ante- 5. Complications of a posterior sternoclavicular rior paralysis in the young athlete. J Bone Joint Surg Am dislocation may be serious and eventually life 61:825–832 Hall R, Calvert P (1995) Stress fracture of the acromion: an threatening. unusual mechanism and review of the literature. J Bone Joint Surg Br 77:153–154 Scapular, Clavicular, Acromioclavicular and Sternoclavicular Joint Injuries 181

Haupt HA (2001) Upper extremity injuries associated with Petersson CJ, Redlund-Johnell I (1983) Radiographic joint strength training. Clin Sports Med 20:481–490 space in normal acromioclavicular joints. Acta Orthop Heers G, Hedtmann A (2005) Correlation of ultrasono- Scand 54:431–433 graphic fi ndings to Tossy’s and Rockwood’s classifi cation Phillips AM, Smart C, Gromm AFG (1998) Acromioclavicular of acromioclavicular joint injuries. Ultrasound Med Biol dislocation. Conservative or operative therapy. Clin Orthop 31(6):725–732 353:10–17 Heinig CF (1968) Retrosternal dislocation of the clavicle. Early Renfree KJ, Wright TW (2003) Anatomy and biomechanics recognition, X-ray diagnosis, and management. J Bone of the acromioclavicular and sternoclavicular joints. Clin Joint Surg Am 50:830 Sports Med 22:219–238 Hobbs DW (1968) Sternoclavicular joint: a new axial radio- Rockwood CA Jr (1984) Subluxations and dislocations about graphic view. Radiology 90:801 the shoulder. In: Rockwood CA Jr (ed) Fractures in adults. Jordan LK, Kenter K, Griffi ths HL (2002) Relationship between J.B. Lippincott, Philadelphia, p 722 MRI and clinical fi ndings in the acromioclavicular joint. Rockwood CA Jr, Wirth MA (1996) Injuries to the sternocla- Skeletal Radiol 31:516–521 vicular joint. In: Rockwood CA Jr, Green DP, Bucholz RW Jost B, Zumstein M, Pfi rmann C et al. (2005) MRI fi ndings in et al. (eds) Rockwood and Green’s Fractures in adults. Lip- throwing shoulders. Abnormalities in professional hand- pincott-Raven, Philadelphia, pp 1415–1471 ball players. Clin Orthop Rel Res 434:130–137 Rogers LF (1983) The radiology of sports injuries. Curr Probl Kaplan P, Resnick D (1986) Stress-induced osteolysis of the Diagn Radiol 12:1 clavicle. Radiology 158:139–140 Roset-Llobet J, Salo-Orfi la JM (1998) Sports-related stress frac- Kelly BT, Barnes RP, Powelle JW et al. (2004) Shoulder inju- ture of the clavicle: a case report. Int Orthop 22:266–268 ries to quarterbacks in the National Football League. Am J Rowe CR (1968) An atlas of anatomy and treatment of midcla- Sports Med 32(2):328–331 vicular fractures. Clin Orthop Relat Res 58:29–42 Klein MA, Spreitzer AM, Miro PA et al. (1997) MR imaging of Rupp S, Seil R, Kohn D (1998) Surgical reconstruction of a the abnormal sternoclavicular joint – a pictorial essay. Clin stress fracture of the acromion after arthroscopic subacro- Imaging 21:138–143 mial decompression in an elite tennis player. Arthroscopy Kocher MS, Feagin JA (1996) Shoulder injuries during alpine 14:106–108 skiing. Am J Sports Med 24(5) 665–669 Salter RB, Harris WR (1963) Injuries involving the epiphyseal Kocher MS, Waters PM, Micheli LJ (2000) Upper extremity plate. J Bone Joint Surg Am 45:587–622 injuries in the paediatric athlete. Sports Med 30(2):117– Sandrock A (1975) Another sports fatigue fracture. Stress fracture 135 of the coracoid process of the scapula. Radiology 117:274 Levine AH, Pais MJ, Schwartz EE (1976) Posttraumatic osteoly- Scavenius M, Iversen BF (1992) Nontraumatic clavicular oste- sis of the distal clavicle with emphasis on early radiologic olysis in weight lifters. Am J Sports Med 20:463–467 changes. Am J Roentgenol 127:781–784 Schils JP, Freed HA, Richmond BJ et al. (1990) Stress fracture Lucas DB (1973) Biomechanics of the . Arch Surg of the acromion. Am J Roentgenol 155(5):1140–1141 107:425–432 Shaffer BS (1999) Painful conditions of the acromioclavicular Ludig T, Walter F, Chapuis D et al. (2001) MR imaging evalu- joint. J Am Acad Orthop Surg 7:176–188 ation of suprascapular nerve entrapment. Eur Radiol Shellhaas JS, Glaser DL, Drezner JA (2004) Distal clavicular 11:2161–2169 stress fracture in a female weight lifter. Am J Sports Med Mallon WJ, Colosimo AJ (1995) Acromioclavicular joint injury 32(7):1755–1758 in competitive golfers. J South Orthop Assoc 4(4):277–282 Shubin Stein BE, Wiater M, Pfaff C et al. (2001) Detection of Matthews LS, Simonson BG, Wolock BS (1993) Osteolysis in acromioclavicular joint pathology in asymptomatic shoul- the distal clavicle in a female body builder. Am J Sports ders with magnetic resonance imaging. J Shoulder Elbow Med 21:150–152 Surg 10(3):204–208 Montagna P, Colonna S (1993) Suprascapular neuropathy Stenlund B, Goldie I, Marions O (1992) Diminished space in restricted to the infraspinatus muscle in volleyball players. the acromioclavicular joint in forced arm adduction as Acta Neurol Scand 87:248–250 a radiographic sign of degeneration and osteoarthrosis. Morisawa K, Umemura A, Kitamura T et al. (1996) Apophysitis Skeletal Radiol 21:529–533 of the acromion. J Shoulder Elbow Surg 5:153–156 Ticker JB, Djurasovic M, Strauch RJ et al. (1998) The incidence Naraen A, Giannikas K, Livesley P (1999) Overuse epiphyseal of ganglion cysts and other variations in anatomy along injury of the coracoid process as a result of archery. Int J the course of the suprascapular nerve. J. Shoulder Elbow Sports Med 20:53–55 Surg 7:472–478 Needell SD, Zlatkin MB, Sher JS et al. (1996) MR imaging of the Tossy JD, Mead NC, Sigmond HM (1963) Acromioclavicular rotator cuff: peritendinous and bone abnormalities in an separations: useful and practical classifi cation for treat- asymptomatic population. Am J Roentgenol 166:863–867 ment. Clin Orthop 28:111–119 Neer CS, Rockwood CA Jr (1975) Fractures and dislocations Turnbull JR (1998) Acromioclavicular joint disorders. Med Sci of the shoulder. In: Rockwood CA Jr, Green DP (eds) Frac- Sports Exerc 30(4):S26–32 tures. Lippincott Co, Philadelphia, p 585 Veluvolu P, Kohn HS, Guten GN et al. (1988) Unusual stress Pasque CB, Hewett TE (2000) A prospective study of high fracture of the scapula in a jogger. Clin Nucl Med 13(7):531– school wrestling injuries. Am J Sports Med 28(4):509–515 532 Patten RM (1995) Atraumatic osteolysis of the distal clavicle: Wallace WA, Hellier M (1983) Improving radiographs of the MR fi ndings. J Comput Assist Tomogr 19:92–95 injured shoulder. Radiography 49:229–233 Petersson CJ (1987) The acromioclavicular joint in rheuma- Waninger KN (1997) Stress fracture of the clavicle in a col- toid arthritis. Clin Orthop 223:86–93 legiate diver. Clin J Sport Med 7:66–68 182 P. Brys and E. Geusens

Ward WG, Bergfeld JA, Carson WG (1994) Stress fracture of the Wulker N (1998) Applied biomechanics. In: Fu FH, Ticker JB, base of the acromial process. Am J Sports Med 22(1):146– Imhoff AB (eds) Atlas of shoulder surgery. Appleton and 147 Lange, Stanford (CT), pp 30–52 Wickiewicz TL (1983) Acromioclavicular and sternoclavicular Yu JS, Dardani M, RA Fischer (2000) MR observations of post- joint injuries. Clin Sports Med 2(2):429–438 traumatic osteolysis of the distal clavicle after traumatic Wirth MA, Rockwood CA Jr (1996) Acute and chronic trau- separation of the acromioclavicular joint. J Comp Assist matic injuries of the sternoclavicular joint. J Am Acad Tomogr 24(1):159–164 Orthop Surg 4:268–278 Zanca P (1971) Shoulder pain: involvement of the acromio- Wu CD, Chen YC (1998) Stress fracture of the clavicle in a pro- clavicular joint – analysis of 1000 cases. Am J Roentgenol fessional baseball player. J Shoulder Elbow Surg 7:164–167 112:493–506