Matthieu J C M Rutten

James M P Collins

Maarten C De

Waal Malefijt

Lambertus A L M Kiemeney

Gerrit Jager

UNSUSPECTED SONOGRAPHIC FINDINGS IN PATIENTS WITH POST-TRAUMATIC SHOULDER COMPLAINTS

Keywords: Ultrasound, Shoulder, Trauma Ultrasound, Shoulder, Trauma

niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

INTRODUCTION

Shoulder pain is frequently caused by an injury. Of all patients with shoulder pain who visit primary care physicians in the United States, one third (33.2%) present after an injury and in the other two thirds the cause is non-traumatic. 1 Males and younger adults (age < 52) more often associate their shoulder pain with previous injury. 1 These shoulder injuries may remain undetected in the acute phase.

Many studies have proven the efficacy of ultrasound (US) in the diagnosis of partial-and full-thickness rotator cuff tears (RCT's) [2][3][4][5][6][7][8] but immediately following trauma US is often not performed because its value is considered limited.

Furthermore conventional x-ray's are often inconclusive for the detection of nondisplaced fractures of the tuberosity complex of the humerus. 9 For this reason diagnosis is often delayed which may cause longstanding shoulder complaints, leading to temporary disability and considerable lost earnings. 10 We hypothesize that many patients with shoulder complaints following trauma have undetected and unsuspected shoulder injuries which may have clinical consequences.

We prospectively assessed the frequency of abnormal sonographic findings in patients with shoulder complaints following trauma in whom US was not considered at the time of and following trauma and secondly we assessed the effect of these findings on therapeutic strategy.

MATERIAL AND METHODS

Our institutional review board approved the study protocol and informed consent was obtained from all patients. This prospective study was performed during a two year period. In this period referring physicians were requested to refer patients with shoulder complaints (pain and/or disability) following trauma in whom diagnostic imaging with US, CT or MRI was not considered. Trauma was defined as a serious injury to the shoulder, which urged the patient to seek medical care.

Time between trauma and referral should be at least two weeks and should not exceed one year. Furthermore the referring physicians were requested to fill in a questionnaire about the working diagnosis and treatment before referral. A second survey within four weeks following US enquired about change in diagnosis and treatment.

Patients

Fifty consecutive patients (29 women and 21 men, age range 21-80, mean age 49 years) were included.

Patients were referred by general practitioners (n=22) and orthopedic surgeons (n=28). Time between trauma and the first visit to the general practitioner or orthopedic surgeon ranged from 0-285 days (mean 38 days), and the time between trauma and the US examination ranged from 14-304 days (mean 69 days). The referring physicians were asked about their working diagnosis and therapy strategy. Patients with pre-existent shoulder complaints or previous surgery were excluded from this study. In the follow up of the patients, who were examined with US, we retrospectively evaluated the patient files if conventional X-ray, MR imaging, and/or open or arthroscopic surgery was performed. In all fifty patients conventional plain radiographs were available, whereas US findings could be associated with MRI and surgical findings in 10 and 19 patients, respectively.

Ultrasound examination

The US examinations were performed with an APLIO (Toshiba Medical Systems, Tokyo, Japan) using a 12 (5 -14) MHz broadband linear-array transducer (Toshiba PLF-805ST). Patients were examined seated on a swivel chair, facing the examiner. A standardized US imaging protocol of the shoulder was used. [11][12][13][14] All sonograms were performed by two radiologists, one experienced (>15 years) musculoskeletal radiologist (M.J.R.) and one experienced (>20 years) abdominal radiologist (G.J.), who had one year experience in performing US of the shoulder.

The patients were examined by both examiners separately, one after the other.

Both were blinded to the results of previously performed examinations and to their mutual findings. Following the US examinations consensus reading was performed. When discrepant findings between the two readers were found the patient was at the same sitting re-examined by both readers together to determine the cause of the discrepancy.

Plain radiographs

All 50 patients underwent a radiographic examination (i.e., trauma series), which consisted of an anteroposterior view (external and/or internal rotation of the humerus), an axillary view and a transscapular view of the shoulder. In 33 patients plain radiographs of the shoulder were obtained following trauma. In the remaining 17 patients a fracture was not suspected clinically. They underwent plain radiography subsequently in conjunction with their US examination.

Following the US examinations both sonologists performed a consensus reading of all 33 initially obtained plain radiographs. If there was a discrepancy between the US findings and the plain radiographic findings new trauma series were obtained and if these were not conclusive additional radiographic views were obtained. The image projection of these additional views were determined according to the US findings, tangent to the expected fracture (Fig. 1).

Magnetic Resonance Imaging (MRI)

In 10 patients MR images were obtained with a 1.5-T scanner (Vision, Siemens Medical systems, Erlangen, Germany) using a surface coil. Indications for the MR examinations were to verify sonographic findings e.g., fractures not visible on plain radiographs (n=2) and rotator cuff tears (n=2), to provide the surgeon with more anatomical information in case surgery was considered, and for the detection of intraarticular pathology (n=6

Image evaluation

Sonographic examinations were evaluated for abnormalities of the deltoid muscle, subacromial-subdeltoid bursa, rotator cuff, long head of the biceps tendon and the proximal humerus including the tuberosity complex.

According to the criteria as established in the literature, [15][16][START_REF] Mack | US evaluation of the rotator cuff[END_REF][START_REF] Middleton | Sonographic detection of rotator cuff tears[END_REF][START_REF] Brandt | Rotator cuff sonography: A reassessment[END_REF][START_REF] Rutten | Ultrasound of the rotator cuff: pitfalls, limitations and artifacts[END_REF] a full-thickness rotator cuff tear (FTT) is defined as non-visualization or absence of the rotator cuff, or a full-thickness rotator cuff discontinuity, and a partial-thickness rotator cuff tear (PTT) as a focal thinning of the rotator cuff, loss of convexity of the outer cuff border and a hypoechoic defect involving the articular or bursal side or within the tendon.

Sonographic features of bone fracture are: periosteal elevation, cortical bone discontinuity (Fig. 2a and Fig. 3a andb), step-off deformity with one or more hyperechoic reflections (i.e., avulsed, dislocated (Fig. 1a) or impacted bone fragments), 9,[START_REF] Cicak | Hill-sachs lesion in recurrent shoulder dislocation: sonographic detection[END_REF] and the double line sign (two parallel hyperechoic lines). 1).

Statistical analysis

For the analyses, we used descriptive statistics only. Because of the relatively small number of patients, it was not considered useful to use inferential statistics.

For the descriptive statistics, we calculated means and standard deviations for continuous variables and percentages (i.e., prevalences) for categorical variables.

For the interrater reproducibility between the 2 sonologists, we calculated Cohen's kappa statistic for fractures (yes vs. no) and ruptures (no vs. partial vs. total).

RESULTS

Fifty patients (30 right and 20 left shoulders) were sonographically examined within 14-304 days (average 69 days) following trauma. The mechanism of trauma was a direct fall on the shoulder (n=26), a fall on a hyperextended arm (n=8), falling while grabbing (hyperextension with traction) (n=10) and various other causes (n=6) such as luxation, forced external rotation or forced hyperextension with abduction.

US showed no abnormalities in 5 (10%) patients and pathologic findings (proximal humerus fracture, RCT's, long head of the biceps tendon luxation or dislocation) in 45 (90%) of the patients. Both observers detected all fractures.

Therefore, the interobserver agreement for the sonographic detection of fractures was perfect (Cohen's kappa is 1.0). The less experienced sonographer interpreted one PTT as tendinosis (Fig. 3), while in the remaining 49 (98%) cases both observers were in agreement, which each other's sonographic findings. The interobserver agreement for the sonographic detection of RCT's was almost perfect (Cohen's kappa is 0.96).

Rotator cuff tears

In 43 (86%) of the 50 patients one or more RCT's were detected with US. We identified 22 FTT and 16 PTT in the supraspinatus tendon and 7 FTT and 6 PTT in the subscapularis tendon. One FTT was detected in the infraspinatus tendon and no tears were detected in the teres minor tendon.

A RCT without other accompanying posttraumatic shoulder pathology was sonographically depicted in 15 of the 43 cases, whereas 28 patients with a RCT suffered from accompanying fractures of the proximal humerus (n=23) and/or subluxation (n=3) or dislocation (n=4) of the long head of the biceps tendon. Four PTT's were accompanied by 3 subluxated and 1 dislocated biceps tendon and 3

FTT's by a dislocated long head of the biceps tendon.

Fractures

In 25 (50%) of the 50 patients a fracture of the proximal humerus was detected sonographically and confirmed with the initially or additionally obtained plain radiographs and/or with MR imaging. In the remaining 25 patients no fracture could be detected with either imaging technique. In the patient group, who initially underwent plain radiography (n=33), a total of 19 fractures were found. However, only 9 (47%) of these fractures were detected prospectively. At retrospective review of the initially obtained plain radiographs 5 additional fractures were detected.

Seven (28%) of the 25 fractures could only be depicted after obtaining additional projections (Fig. 1) or were only visible on additionally obtained radiographs (Fig. 2) or with MRI (Fig. 3). Sonography did not miss any fracture depicted by plain radiography.

In the patient group (n=17), who did not undergo radiography initially, 6

fractures were detected with sonography and confirmed with conventional radiographs.

According to Neer's four-segment classification for fractures of the proximal humerus, [START_REF] Neer | Displaced proximal humeral fractures. 1. Classification and evaluation[END_REF] 22 patients (92%) had a non-or minimally displaced one-part fracture, and 3 patients a two-part fracture. None of the patients suffered from a three-part or four-part fracture.

In 23 of the 25 patients with a fracture this was accompanied by a RCT ( 15PTT and 8 FTT).

Associated posttraumatic pathologic musculoskeletal findings

A thickened subacromial-subdeltoid bursa (i.e., bursitis) (Fig. 2a) was sonographically diagnosed in 2 patients. This is either caused by trauma or due to chronic impingement. In neither patient was a fracture or RCT found. Subluxation of the long head of the biceps tendon (Fig. 4a) was diagnosed in 3 patients and complete dislocation of the biceps tendon (Fig. 4b) was diagnosed in 4 patients. These biceps tendon subluxation and dislocations were accompanied by PTT (n=4) or FTT (n=3) of the subscapularis (n=2) and/or supraspinatus tendon (n=5).

Working diagnosis and therapeutic strategy changes

Compared to the initial diagnosis and therapy the referring physician stated that sonographic findings affected the working diagnosis and therapeutic strategy in 37 (74%) and 26 (52%) patients, respectively.

In

DISCUSSION

Trauma-related shoulder disorders are frequently initially missed, affecting quality of life. [START_REF] Malhotra | What are we missing: results of a 13month active follow-up program at a level I trauma center[END_REF][START_REF] Lichtveld | Background and consequences of injuries missed when diagnosing severely injured accident victims in prehospital care in patients transported by ambulance to the University Medical Centre in Utrecht, 1999-2000[END_REF] In this prospective study we demonstrate that patients with posttraumatic shoulder complaints, have a high prevalence of rotator cuff tears (86%) and fractures (50%) of the proximal humerus. This confirms the findings of Sørensen et al, 4 who reported that clinical examination underestimates the prevalence and severity of acute RCT's and fractures. This has also been indicated by Patten et al, 9 who showed that 10 (42%) of the 24 sonographically detected greater tuberosity fractures were missed with plain radiography. In our study, 10 (53%) of the 19 fractures were not depicted at the initial reading. Even retrospectively, 26% (5 of 19) of these fractures could not be depicted from the initially obtained trauma series. Of all 25 fractures in our study 7 (28%) could not be depicted from the trauma series, whereas all 25 fractures were depicted Another characteristic sonographic feature of a fracture is the double line sign.

22

In all but two patients with a fracture of the proximal humerus a PTT or FTT could be detected. This is in contrast with Patten et al, 9 who suggests that this combination can be found in only 17-25%. The higher number of RCT in our study is probably due to the selected patients, e.g., patients with persistent shoulder complaints following trauma, and may also be related to the injury mechanism or severity of trauma. Age seems not to be the reason for the relatively high frequency of RCT in our study, in the age group of 21 to 30 years the frequency of RCT was 33%, in the other age groups the frequency was (80-100%). In this study no surgical therapy was performed in any of the 24 patients with a fracture of the proximal humerus.

In the current study US was not performed immediately after injury or in the emergency setting. Possible disadvantages of performing US in the acute phase is the detection of chronic, irrelevant asymptomatic RCT's [START_REF] Reilly | Dead men and radiologists don't lie: a review of cadaveric and radiological studies of rotator cuff tear prevalence[END_REF] and the decreased diagnostic performance of US due to limited shoulder motion, necessary for visualization of the entire rotator cuff. 5 However, Teefey et al [START_REF] Teefey | Sonographic differences in the appearance of acute and chronic full-thickness rotator cuff tears[END_REF] showed that on the basis of location (midsubstance) and associated findings (the presence of joint or bursal fluid) acute and chronic RCT can be differentiated. Farin et al 5 and

Sørensen et al 4 demonstrated that adequate sonographic examination was feasible in 88% in the acute phase.

In our study we found that referring physicians stated that US findings half of the patients supporting the suggestion that sonography reveals clinically relevant findings. [START_REF] Lanzer | Clinical aspects of shoulder injuries[END_REF] We found no previous studies that addressed clinical efficacy, [START_REF] Thornbury | Clinical efficacy of diagnostic imaging: love it or leave it[END_REF] which includes diagnostic impact and the therapeutic efficacy in patients with shoulder complaints following trauma. Change in therapy is more objectively ascertainable but it is difficult to assess to what extent the sonographic diagnosis contributes to the change in therapy e.g., we found that therapeutic strategy changed more often when the initial diagnosis was not changed.

When interpreting the results of our study, some limitations have to be considered. First, the number of patients included in this study is relatively small.

Secondly, the high number of posttraumatic pathologic findings may be biased. It is possible that patient selection was not exactly according the study purpose (e.g., patients with shoulder complaints following trauma in whom US was not considered), but that patients with shoulder complaints following trauma in whom US was already considered also answered the call up.

Thirdly, the methods for assessing diagnostic and therapeutic efficacy are not well established. These are subjective and difficult to quantify. [START_REF] Thornbury | Clinical efficacy of diagnostic imaging: love it or leave it[END_REF] It is possible that patient symptoms were increasing with time and sonographic findings were not the only reason for a change in treatment. Furthermore the second survey we performed 1 month following US, which is not ideal for the assessment of the diagnostic impact and therapeutic efficacy. [START_REF] Thornbury | Clinical efficacy of diagnostic imaging: love it or leave it[END_REF] Therefore, the effect of US imaging on diagnosis and therapeutic strategy may be overestimated.

In the literature there is no consensus about the optimal therapeutic strategy Further studies are needed to prove that early and active referral of these patients for sonographic examination may improve patient outcome. present after an injury and in the other two thirds the cause is non-traumatic. 1 Males and younger adults (age < 52) more often associate their shoulder pain with previous injury. 1 These shoulder injuries may remain undetected in the acute phase.

F

Many studies have proven the efficacy of ultrasound (US) in the diagnosis of partial-and full-thickness rotator cuff tears (RCT's) 2-8 but immediately following trauma US is often not performed because its value is considered limited.

Furthermore conventional x-ray's are often inconclusive for the detection of nondisplaced fractures of the tuberosity complex of the humerus. 9 For this reason diagnosis is often delayed which may cause longstanding shoulder complaints, leading to temporary disability and considerable lost earnings. 10 We hypothesize that many patients with shoulder complaints following trauma have undetected and unsuspected shoulder injuries which may have clinical consequences.

We prospectively assessed the frequency of abnormal sonographic findings in patients with shoulder complaints following trauma in whom US was not considered at the time of and following trauma and secondly we assessed the effect of these findings on therapeutic strategy. In the follow up of the patients, who were examined with US, we retrospectively evaluated the patient files if conventional X-ray, MR imaging, and/or open or arthroscopic surgery was performed. In all fifty patients conventional plain radiographs were available, whereas US findings could be associated with MRI and surgical findings in 10 and 19 patients, respectively.

Ultrasound examination

The US examinations were performed with an APLIO (Toshiba Medical Systems, Tokyo, Japan) using a 12 (5 -14) MHz broadband linear-array transducer (Toshiba PLF-805ST). Patients were examined seated on a swivel chair, facing the examiner. A standardized US imaging protocol of the shoulder was used. [11][12][13][14] All sonograms were performed by two radiologists, one experienced (>15 years) musculoskeletal radiologist (M.J.R.) and one experienced (>20 years) abdominal radiologist (G.J.), who had one year experience in performing US of the shoulder.

The patients were examined by both examiners separately, one after the other.

Both were blinded to the results of previously performed examinations and to their mutual findings. Following the US examinations consensus reading was performed. When discrepant findings between the two readers were found the patient was at the same sitting re-examined by both readers together to determine the cause of the discrepancy. Following the US examinations both sonologists performed a consensus reading of all 33 initially obtained plain radiographs. If there was a discrepancy between the US findings and the plain radiographic findings new trauma series were obtained and if these were not conclusive additional radiographic views were obtained. The image projection of these additional views were determined according to the US findings, tangent to the expected fracture (Fig. 1).

Magnetic Resonance Imaging (MRI)

In 10 patients MR images were obtained with a 1.5-T scanner (Vision, Siemens Medical systems, Erlangen, Germany) using a surface coil. Indications for the MR examinations were to verify sonographic findings e.g., fractures not visible on plain radiographs (n=2) and rotator cuff tears (n=2), to provide the surgeon with more anatomical information in case surgery was considered, and for the detection of intraarticular pathology (n=6

Image evaluation

Sonographic examinations were evaluated for abnormalities of the deltoid muscle, subacromial-subdeltoid bursa, rotator cuff, long head of the biceps tendon and the proximal humerus including the tuberosity complex.

According to the criteria as established in the literature, [15][16][START_REF] Mack | US evaluation of the rotator cuff[END_REF][START_REF] Middleton | Sonographic detection of rotator cuff tears[END_REF][START_REF] Brandt | Rotator cuff sonography: A reassessment[END_REF][START_REF] Rutten | Ultrasound of the rotator cuff: pitfalls, limitations and artifacts[END_REF] a full-thickness rotator cuff tear (FTT) is defined as non-visualization or absence of the rotator cuff, or a full-thickness rotator cuff discontinuity, and a partial-thickness rotator cuff tear (PTT) as a focal thinning of the rotator cuff, loss of convexity of the outer cuff border and a hypoechoic defect involving the articular or bursal side or within the tendon.

Sonographic features of bone fracture are: periosteal elevation, cortical bone discontinuity (Fig. 2a and Fig. 3a andb), step-off deformity with one or more hyperechoic reflections (i.e., avulsed, dislocated (Fig. 1a) or impacted bone fragments), 9,[START_REF] Cicak | Hill-sachs lesion in recurrent shoulder dislocation: sonographic detection[END_REF] and the double line sign (two parallel hyperechoic lines). reading of all 50 trauma series including the additionally obtained plain radiographs was performed by consensus by the two sonologists (Table 1).

Statistical analysis

For the analyses, we used descriptive statistics only. Because of the relatively small number of patients, it was not considered useful to use inferential statistics.

For the descriptive statistics, we calculated means and standard deviations for continuous variables and percentages (i.e., prevalences) for categorical variables.

For the interrater reproducibility between the 2 sonologists, we calculated Cohen's kappa statistic for fractures (yes vs. no) and ruptures (no vs. partial vs. total).

RESULTS

Fifty patients (30 right and 20 left shoulders) were sonographically examined within

Rotator cuff tears

In 43 (86%) of the 50 patients one or more RCT's were detected with US. We identified 22 FTT and 16 PTT in the supraspinatus tendon and 7 FTT and 6 PTT in the subscapularis tendon. One FTT was detected in the infraspinatus tendon and no tears were detected in the teres minor tendon.

A RCT without other accompanying posttraumatic shoulder pathology was sonographically depicted in 15 of the 43 cases, whereas 28 patients with a RCT suffered from accompanying fractures of the proximal humerus (n=23) and/or subluxation (n=3) or dislocation (n=4) of the long head of the biceps tendon. Four PTT's were accompanied by 3 subluxated and 1 dislocated biceps tendon and 3

FTT's by a dislocated long head of the biceps tendon.

Fractures

In 25 (50%) of the 50 patients a fracture of the proximal humerus was detected sonographically and confirmed with the initially or additionally obtained plain radiographs and/or with MR imaging. In the remaining 25 patients no fracture could be detected with either imaging technique. In the patient group, who initially underwent plain radiography (n=33), a total of 19 fractures were found. However, only 9 (47%) of these fractures were detected prospectively. At retrospective review of the initially obtained plain radiographs 5 additional fractures were detected.

Seven (28%) of the 25 fractures could only be depicted after obtaining additional projections (Fig. 1) or were only visible on additionally obtained radiographs (Fig. 2) or with MRI (Fig. 3). Sonography did not miss any fracture depicted by plain radiography.

In the patient group (n=17), who did not undergo radiography initially, 6

fractures were detected with sonography and confirmed with conventional radiographs.

According to Neer's four-segment classification for fractures of the proximal humerus, [START_REF] Neer | Displaced proximal humeral fractures. 1. Classification and evaluation[END_REF] 22 patients (92%) had a non-or minimally displaced one-part fracture, and 3 patients a two-part fracture. None of the patients suffered from a three-part or four-part fracture.

In 23 of the 25 patients with a fracture this was accompanied by a RCT ( 15PTT and 8 FTT).

Associated posttraumatic pathologic musculoskeletal findings

A thickened subacromial-subdeltoid bursa (i.e., bursitis) (Fig. 2a) was sonographically diagnosed in 2 patients. This is either caused by trauma or due to chronic impingement. In neither patient was a fracture or RCT found.

Working diagnosis and therapeutic strategy changes

Compared to the initial diagnosis and therapy the referring physician stated that sonographic findings affected the working diagnosis and therapeutic strategy in 37 (74%) and 26 (52%) patients, respectively.

In 13 (26%) of the 50 patients US confirmed the working diagnosis. In 19 (38%) patients US confirmed the working diagnosis, but also detected additional traumatically caused pathology, and in 18 (36%) patients US findings were not concurrent with the clinical working diagnosis.

Therapy was changed because although the diagnosis was confirmed, probably due to more diagnostic certainty in 9 (69%) of the 13 patients. Therapy was also changed in 11 (58%) of the 19 patients with whom the working diagnosis was confirmed and additional posttraumatic pathology was found. Finally, in only 6 (33%) of the 18 patients with whom the sonographic findings and working diagnosis did not concurred, therapy did change. These six relatively young (37 to 52 years) patients presented with a FTT, who were operated upon following US after initially conservative treatment. In the remaining 12 patients the initially initiated conservative therapy was continued despite the sonographic finding of a

DISCUSSION

Trauma-related shoulder disorders are frequently initially missed, affecting quality of life. [START_REF] Malhotra | What are we missing: results of a 13month active follow-up program at a level I trauma center[END_REF][START_REF] Lichtveld | Background and consequences of injuries missed when diagnosing severely injured accident victims in prehospital care in patients transported by ambulance to the University Medical Centre in Utrecht, 1999-2000[END_REF] In this prospective study we demonstrate that patients with posttraumatic shoulder complaints, have a high prevalence of rotator cuff tears (86%) and fractures (50%) of the proximal humerus. This confirms the findings of Sørensen et al, 4 who reported that clinical examination underestimates the prevalence and severity of acute RCT's and fractures. This has also been indicated by Patten et al, 9 who showed that 10 (42%) of the 24 sonographically detected greater tuberosity fractures were missed with plain radiography. In our study, 10 (53%) of the 19 fractures were not depicted at the initial reading. Even retrospectively, 26% (5 of 19) of these fractures could not be depicted from the initially obtained trauma series. Of all 25 fractures in our study 7 (28%) could not be depicted from the trauma series, whereas all 25 fractures were depicted F o r P e e r R e v i e w 14 sonographically. 9,[START_REF] Rutten | Double Line Sign: A helpful sonographic sign to detect occult fractures of the proximal humerus[END_REF] A fracture can easily be identified sonographically as a discontinuity of the cortical bone, when scanning perpendicular to the fracture line.

Another characteristic sonographic feature of a fracture is the double line sign.

22

In all but two patients with a fracture of the proximal humerus a PTT or FTT could be detected. This is in contrast with Patten et al, 9 who suggests that this combination can be found in only 17-25%. The higher number of RCT in our study is probably due to the selected patients, e.g., patients with persistent shoulder complaints following trauma, and may also be related to the injury mechanism or severity of trauma. Age seems not to be the reason for the relatively high frequency of RCT in our study, in the age group of 21 to 30 years the frequency of RCT was 33%, in the other age groups the frequency was (80-100%). In this study no surgical therapy was performed in any of the 24 patients with a fracture of the proximal humerus.

In the current study US was not performed immediately after injury or in the emergency setting. Possible disadvantages of performing US in the acute phase is the detection of chronic, irrelevant asymptomatic RCT's [START_REF] Reilly | Dead men and radiologists don't lie: a review of cadaveric and radiological studies of rotator cuff tear prevalence[END_REF] and the decreased diagnostic performance of US due to limited shoulder motion, necessary for visualization of the entire rotator cuff. 5 However, Teefey et al [START_REF] Teefey | Sonographic differences in the appearance of acute and chronic full-thickness rotator cuff tears[END_REF] showed that on the basis of location (midsubstance) and associated findings (the presence of joint or bursal fluid) acute and chronic RCT can be differentiated. Farin et al 5 and

Sørensen et al 4 demonstrated that adequate sonographic examination was feasible in 88% in the acute phase.

In our study we found that referring physicians stated that US findings half of the patients supporting the suggestion that sonography reveals clinically relevant findings. [START_REF] Lanzer | Clinical aspects of shoulder injuries[END_REF] We found no previous studies that addressed clinical efficacy, [START_REF] Thornbury | Clinical efficacy of diagnostic imaging: love it or leave it[END_REF] which includes diagnostic impact and the therapeutic efficacy in patients with shoulder complaints following trauma. Change in therapy is more objectively ascertainable but it is difficult to assess to what extent the sonographic diagnosis contributes to the change in therapy e.g., we found that therapeutic strategy changed more often when the initial diagnosis was not changed.

When interpreting the results of our study, some limitations have to be considered. First, the number of patients included in this study is relatively small.

Secondly, the high number of posttraumatic pathologic findings may be biased. It is possible that patient selection was not exactly according the study purpose (e.g., patients with shoulder complaints following trauma in whom US was not considered), but that patients with shoulder complaints following trauma in whom US was already considered also answered the call up.

Thirdly, the methods for assessing diagnostic and therapeutic efficacy are not well established. These are subjective and difficult to quantify. [START_REF] Thornbury | Clinical efficacy of diagnostic imaging: love it or leave it[END_REF] It is possible that patient symptoms were increasing with time and sonographic findings were not the only reason for a change in treatment. Furthermore the second survey we performed 1 month following US, which is not ideal for the assessment of the diagnostic impact and therapeutic efficacy. [START_REF] Thornbury | Clinical efficacy of diagnostic imaging: love it or leave it[END_REF] Therefore, the effect of US imaging on diagnosis and therapeutic strategy may be overestimated.

In the literature there is no consensus about the optimal therapeutic strategy

6

 6 Two independent radiologists performed the US examinations during one patient visit.

14 sonographically. 9 ,

 149 [START_REF] Rutten | Double Line Sign: A helpful sonographic sign to detect occult fractures of the proximal humerus[END_REF] A fracture can easily be identified sonographically as a discontinuity of the cortical bone, when scanning perpendicular to the fracture line.

  diagnosis in 74% and the therapeutic strategy in more than

  treatment of RCT's following trauma.[START_REF] Coghlan | Surgery for rotator cuff disease[END_REF][START_REF] Ejnisman | Interventions for tears of the rotator cuff in adults[END_REF] Therefore, additional prospective studies are needed to confirm the hypothesis that early sonographic assessment of the rotator cuff integrity in patients with post traumatic shoulder complaints improves patient outcome and to establish the best time to perform US in these patients.The results of such studies could potentially change the approach of acute injury to the shoulder. It is arguable, considering the limited detection of fractures with conventional radiographs to propose the following algorithm. First do an ultrasound in the acute phase, and if the pain does not subside after a week then take an X-rayIn our study we would not have missed any substantial abnormalities and would have made the right diagnosis in an earlier phase.. It would sure have clarified a lot of pain caused by missed fractures and rotator cuff tears. Dislocations with complete loss of function of course may have to be treated separately in this algorithm, and if US is negative and/or clinical symptoms are related to intraarticular disorders MR arthrography should be performed CONCLUSION Patients with posttraumatic shoulder complaints have a high prevalence of unsuspected and initially missed RCT's and fractures and US is accurate in the detection of clinically relevant trauma-related shoulder pathology.

Fig. 1 .

 1 FIGURES AND LEGENDS

Fig. 2 . 23 Fig. 3 .

 2233 Fig. 2. 68-year-old woman with shoulder pain and disability following a fall on the

Fig. 4 3 74%INTRODUCTION

 43 Fig. 4 Subluxation (A) and complete dislocation (B) of the long head of the biceps

  Our institutional review board approved the study protocol and informed consent was obtained from all patients. This prospective study was performed during a two year period. In this period referring physicians were requested to refer patients with shoulder complaints (pain and/or disability) following trauma in whom diagnostic imaging with US, CT or MRI was not considered. Trauma was defined as a serious injury to the shoulder, which urged the patient to seek medical care.Time between trauma and referral should be at least two weeks and should not exceed one year. Furthermore the referring physicians were requested to fill in a questionnaire about the working diagnosis and treatment before referral. A second survey within four weeks following US enquired about change in diagnosis and treatment.PatientsFifty consecutive patients (29 women and 21 men, age range 21-80, mean age 49 years) were included.Patients were referred by general practitioners (n=22) and orthopedic surgeons (n=28). Time between trauma and the first visit to the general practitioner or orthopedic surgeon ranged from 0-285 days (mean 38 days), and the time between trauma and the US examination ranged from 14-304 days (mean 69 days). The referring physicians were asked about their working diagnosis and therapy strategy. Patients with pre-existent shoulder complaints or previous surgery were excluded from this study.

6

 6 Two independent radiologists performed the US examinations during one patient visit.

  underwent a radiographic examination (i.e., trauma series), which consisted of an anteroposterior view (external and/or internal rotation of the humerus), an axillary view and a transscapular view of the shoulder. In 33 patients plain radiographs of the shoulder were obtained following trauma. In the remaining 17 patients a fracture was not suspected clinically. They underwent plain radiography subsequently in conjunction with their US examination.

22

 22

9

 9 Initial plain radiographs were evaluated prospectively in routine practice by residents and radiologists with a varying level of experience. The final retrospective

14 -

 14 304 days (average 69 days) following trauma. The mechanism of trauma was a direct fall on the shoulder (n=26), a fall on a hyperextended arm (n=8), falling while grabbing (hyperextension with traction) (n=10) and various other causes (n=6) such as luxation, forced external rotation or forced hyperextension with abduction.US showed no abnormalities in 5 (10%) patients and pathologic findings (proximal humerus fracture, RCT's, long head of the biceps tendon luxation or dislocation) in 45 (90%) of the patients. Both observers detected all fractures.Therefore, the interobserver agreement for the sonographic detection of fractures Cohen's kappa is 1.0). The less experienced sonographer interpreted one PTT as tendinosis (Fig.3), while in the remaining 49 (98%) cases both observers were in agreement, which each other's sonographic findings. The interobserver agreement for the sonographic detection of RCT's was almost perfect (Cohen's kappa is 0.96).

12 Subluxation

 12 of the long head of the biceps tendon (Fig.4a) was diagnosed in 3 patients and complete dislocation of the biceps tendon (Fig.4b) was diagnosed in 4 patients. These biceps tendon subluxation and dislocations were accompanied by PTT (n=4) or FTT (n=3) of the subscapularis (n=2) and/or supraspinatus tendon (n=5).

13 FTT in 4

 134 patients, a PTT in 4 patients, a non-displaced fracture of the greater tuberosity in 4 patients. In 26 of the 50 patients US changed therapy strategy. In 21 of these 26 patients conservative therapy (rest, physiotherapy, subacromial injections) was changed to surgical treatment following US. Twenty patients underwent surgical rotator cuff repair of 4 PTT and 16 FTT and one patient because of a luxation of the long head of the biceps tendon in combination with a FTT. In the remaining 5 of the 26 patients conservative treatment was changed in a lighter physiotherapy program (n=4) or rest (n=2).

  diagnosis in 74% and the therapeutic strategy in more than

Fig. 1 .

 1 FIGURES AND LEGENDS

Fig. 2 . 23 Fig. 3 .

 2233 Fig. 2. 68-year-old woman with shoulder pain and disability following a fall on the

Fig. 4 Fig. 1 .Fig. 1 .Fig. 2 .

 4112 Fig. 4 Subluxation (A) and complete dislocation (B) of the long head of the biceps

Fig. 2 .Fig. 2 .

 22 Fig 2B Fig. 2. 68-year-old woman with shoulder pain and disability following a fall on the right shoulder.A, The initial radiographs, obtained 6 days following trauma, were interpreted as normal. B, Long axis sonogram of the supraspinatus tendon (SSP) shows a cortical bone discontinuity (large arrow) at the junction between the greater tuberosity (GT) and the humeral head, representing a non-displaced greater tuberosity fracture. The thickened subacromial-subdeltoid bursa (small arrows) is either caused by trauma or due to chronic impingement. C, The radiographs obtained 1 month following trauma showed a radiolucent zone (arrows) along the fracture line due to bone resorption indicative of active bone repair.

Fig. 3 .Fig. 3 .Fig. 3 .

 333 Fig 3A Fig. 3. 43-year-old man with pain and disability of the shoulder 19 days following a fall on the right shoulder. A, B, Long axis sonograms of the supraspinatus tendon (SSP) showing corticol bone discontinuities (large arrows) and outpouchings of cortical bone (small arrows) representing fractures of the greater tuberosity (GT), which are frequently associated with intrasubstance rotator cuff tears (asterisks). C, A radiograph obtained directly following US could not confirm the US findings. D, Coronal T1-weighted FSE images with fat saturation of a MR arthrogram confirmed the US findings by showing an elevated signal of the greater tuberosity (GT) due to oedema because of a fracture and a longitudinally orientated intrasubstance tear (arrow) of the supraspinatus tendon (SSP).

Fig. 3 .Fig. 4 Fig. 4

 344 Fig 3D Fig. 3. 43-year-old man with pain and disability of the shoulder 19 days following a fall on the right shoulder. A, B, Long axis sonograms of the supraspinatus tendon (SSP) showing corticol bone discontinuities (large arrows) and outpouchings of cortical bone (small arrows) representing fractures of the greater tuberosity (GT), which are frequently associated with intrasubstance rotator cuff tears (asterisks). C, A radiograph obtained directly following US could not confirm the US findings. D, Coronal T1-weighted FSE images with fat saturation of a MR arthrogram confirmed the US findings by showing an elevated signal of the greater tuberosity (GT) due to oedema because of a fracture and a longitudinally orientated intrasubstance tear (arrow) of the supraspinatus tendon (SSP).

  [START_REF] Rutten | Double Line Sign: A helpful sonographic sign to detect occult fractures of the proximal humerus[END_REF]

  Initial plain radiographs were evaluated prospectively in routine practice by residents and radiologists with a varying level of experience. The final retrospective reading of all 50 trauma series including the additionally obtained plain radiographs was performed by consensus by the two sonologists (Table

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